JP4847545B2 - Toner and image forming method - Google Patents

Description

  The present invention relates to a toner and an image forming method applied to an image forming apparatus using a heat and pressure fixing device.

  In an image forming apparatus, a recording material (transfer material sheet, electrofax sheet, electrostatic recording paper, OHP (over head projector) by an appropriate image forming process means such as an electrophotographic process, an electrostatic recording process, and a magnetic recording process. As a fixing device that heats and fixes an unfixed image (toner image) of the target image information formed and carried on a sheet, printing paper, format paper, or the like by a transfer method or a direct method as a permanently fixed image on the surface of the recording material The heat roller type device has been widely used. Recently, belt heating systems have been put into practical use from the viewpoint of quick start and energy saving. The device configuration, advantages, and problems of these types of fixing devices are as follows.

i) Heat roller type fixing device This is based on a pressure roller pair of a fixing roller (heating roller) and a pressure roller, and the roller pair is rotated so that a fixing nip portion is a mutual pressure contact portion of the roller pair. Then, a recording material on which an unfixed toner image to be image-fixed is formed is carried and is nipped and conveyed, and the unfixed toner image is heated on the surface of the recording material by the heat of the fixing roller and the pressing force of the fixing nip portion. It is for fixing by pressure.

  In general, the fixing roller has an aluminum hollow metal roller as a base body (core metal), and a halogen lamp as a heat source is inserted and disposed in the inner space thereof. The temperature of the halogen lamp is controlled and controlled so that the temperature is maintained.

  In particular, as a fixing device of an image forming apparatus that performs full-color image formation that requires the ability to sufficiently heat-melt and mix colors of up to four toner image layers, a fixing roller core has a high heat capacity In addition, a rubber elastic layer for wrapping and uniformly melting the toner image around the outer periphery of the metal core is provided, and the toner image is heated through the rubber elastic layer. There is also a configuration in which a heat source is also provided in the pressure roller so that the pressure roller is also heated and temperature-controlled.

  However, in the heat roller type fixing device, even when the power of the image forming apparatus is turned on and at the same time the energization of the halogen lamp, which is the heat source of the fixing device, is started, the heat capacity of the fixing roller is large and the fixing roller and the like are cooled down. A considerable waiting time (wait time) is required until the temperature reaches a predetermined fixing temperature from the state, and the quick start property is lacking. In addition, it is necessary to energize the halogen lamp and maintain the fixing roller at a predetermined temperature control state so that an image forming operation can be executed at any time even when the image forming apparatus is in a standby state (non-image output). There was a problem that the amount was large.

  Further, in the case of using a fixing roller having a particularly large heat capacity, such as the fixing device of the above-described full-color image forming apparatus, a delay occurs in the temperature control and the temperature increase on the surface of the fixing roller. Problems such as offset occurred.

ii) Film Heating Type Fixing Device Film heating type fixing devices have been proposed in, for example, Patent Documents 1 to 4 and the like.

  That is, a nip portion is formed by sandwiching a heat-resistant film (fixing film) between a ceramic heater as a heating element and a pressure roller as a pressure member, and the film in the nip portion and the pressure roller During this period, a recording material on which an unfixed toner image to be image-fixed is formed and supported is introduced and nipped and conveyed together with the film, so that the heat of the ceramic heater is transferred to the recording material through the film at the nip portion. In addition, the non-fixed toner image is fixed to the surface of the recording material by heat and pressure by applying pressure at the nip portion.

  This film heating type fixing device can be configured as an on-demand type device using a ceramic heater and a film having a low heat capacity as a film, and energizes the ceramic heater as a heat source only when the image forming apparatus performs image formation. It is only necessary to generate heat at a predetermined fixing temperature, and the waiting time from the power-on of the image forming apparatus to the image forming executable state is short (quick start property), and the power consumption during standby is greatly reduced (saving) Power).

  However, a full-color image forming apparatus and a fixing device for a high-speed model that require a large amount of heat have drawbacks in terms of heat.

  On the other hand, although toners focusing on the viscoelasticity of resins are disclosed in Patent Documents 5 to 7 and the like regarding toner, in order to achieve both low-temperature fixability and high-temperature offset resistance while adapting to a film heating type fixing device. There is still a need for improvement.

  In order to improve the high temperature offset resistance at the time of fixing, generally, a material having a relatively high releasability such as polyethylene wax or polypropylene wax is used. However, if such a low softening point substance is contained in a large amount, In many cases, developability is poor.

  Generally, in color toners, high temperature offset resistance is improved by applying silicone oil or the like to the surface of the heat fixing roller without adding a release agent. However, the output transfer member obtained in this way has problems such as an unpleasant feeling to the user due to excessive silicone oil or the like adhering to the surface, and difficulty in viewing due to high gloss.

  In order to solve these problems, in Patent Document 8, etc., a low softening point substance is contained in the toner by a polymerization method, and further, by controlling the physical properties of the resin, low temperature fixability, high temperature offset resistance, image glossiness, OHP transmission A combination of a toner satisfying the properties and a heat fixing device is disclosed.

  However, this heat fixing device has a heat roller system, which has advantages such as long life and pressure applied during fixing, but has a long wait time and high power consumption as described above. There was a problem.

  As described above, there is no combination of a toner and a heat fixing device that solves various problems.

JP-A-63-313182 Japanese Patent Laid-Open No. 2-157878 JP-A-4-44075 JP-A-4-204980 Japanese Patent Laid-Open No. 1-128071 JP-A-4-353866 JP-A-6-59504 Japanese Patent Laid-Open No. 10-282822

  An object of the present invention is to provide a toner and an image forming method which have solved the problems of the prior art as described above.

  That is, the object of the present invention is to make the heated part to be heated to a predetermined temperature in a short time (quick start property), to sufficiently secure the fixing property of the toner image in a wide temperature range, It is an object of the present invention to provide a toner and an image forming method capable of achieving uniform gloss (gloss) even in a change.

  Another object of the present invention is to provide a full-color toner and an image forming method capable of obtaining an image having good color reproducibility by mixing multicolor toners sufficiently and having excellent transparency of an OHP image. .

According to a first aspect of the present invention, there is provided at least a heating body fixed at a predetermined position, a fixing belt having an elastic layer having a rubber hardness of 10 to 50 degrees according to JIS-A and facing the heating body, and temperature detection means The recording material is brought into close contact with the heating body through the fixing belt while adjusting the temperature by bringing the temperature detecting means into contact with the inner surface of the fixing belt, and the toner image on the recording material is displayed on the recording material. The temperature detecting means is provided in contact with a position downstream of the fixing nip center where the fixing belt contacts the recording material in the rotation direction, and 10% of the total fixing belt length in the rotation direction from the fixing nip center position. Is a toner applied to an image forming apparatus provided with a heat fixing device provided at a downstream position not less than a length of 50% , and the second is a heating body fixed at least at a predetermined position. And opposite pressure contact with the heating body A fixing belt having an elastic layer having a rubber hardness of 10 to 50 ° according to JIS-A, and a temperature detection means, and the temperature detection means is brought into contact with the inner surface of the fixing belt to adjust the temperature. The recording material is brought into close contact with the heating body to heat and fix the toner image on the recording material to the recording material, and the temperature detecting means is positioned downstream of the center of the nip where the fixing belt contacts the recording material in the rotational direction. contact with are provided, and an image forming method having a fixing nip center position that is provided in 10% of the length more than 50% of the length below a downstream position in the rotational direction full fixing belt length from step.

The feature of the present invention is that the first toner of the present invention and the toner constituting the toner image in the second image forming method are the following (a) to ( h ):
(A) The toner contains 0.5 to 30% by mass of a low softening point substance.
(B) The weight average molecular weight (Mw) in the molecular weight distribution measured by gel permeation chromatography (GPC) of the tetrahydrofuran (THF) soluble content of the toner is 10,000 to 1,000,000, and the weight average The ratio (Mw / Mn) of molecular weight (Mw) to number average molecular weight (Mn) is 3 to 20,
(C) The insoluble content of the toner by Soxhlet extraction with a tetrahydrofuran solvent is 3 to 30% by mass.
(D) storage elastic modulus at a temperature of 50 ° C. of the toner (G _'50) and a storage modulus at a temperature 100 ° C. of the toner (G' ratio of _{100) (G '50 / G} ' 100) is 5,000～70 , 000,
(E) The storage elastic modulus (G ′ ₁₅₀ ) of the toner at a temperature of 150 ° C. is 1 × 10 ³ to 1 × 10 ⁵ (dN / m ² ).
(F) The toner melt index (temperature 135 ° C., load 2.2 kg) in 10 minutes is 1 to 40 g.
(G) The methanol wettability half-value of the toner base particles is 13 to 63%.
(H) In the molecular weight distribution measured by GPC, the low softening point substance has a weight average molecular weight (Mw) to number average molecular weight (Mn) ratio (Mw / Mn) of 1.0 to 1.5.
It is to satisfy.

  The toner and the image forming method of the present invention include the following configurations as preferred embodiments.

  The contact angle with water after heating the toner base particles at 100 ° C. for 2 minutes is 102 to 130 °.

  The average circularity satisfies 0.950 to 1.0 in the particle size distribution according to the equivalent circle diameter of the toner particles measured by the toner flow type particle image analyzer.

  The toner is produced by a polymerization method in which a polymerizable monomer composition containing at least a polymerizable monomer, a low softening point substance, and a colorant is polymerized in a solvent liquid in the presence of a polymerization initiator.

  The fixing belt is not provided with an oil application mechanism.

  The fixing belt has at least a base layer, an elastic layer, and a release layer. The base layer has a thickness of 1 to 200 μm, the elastic layer has a thickness of 100 to 500 μm, and the release layer has a thickness of 1 to 100 μm. is there.

  The elastic layer of the fixing belt contains zinc oxide as a heat conductive material.

While pressing the fixing belt against the recording material at a surface pressure of 9 × 10 ^{3 to} 5 × 10 ⁵ N / m ² , the toner image is fixed by heating and pressing at a fixing speed of 5 to 300 mm / second.

  The heating body is a ceramic heater. In particular, it is made of aluminum nitride.

  According to the present invention, in an image forming method excellent in quick start property and power saving, the glossiness of a fixed image can be kept uniform, psychologically giving a user peace of mind, and an overhead projector film (OHP) image. High-quality images with excellent transparency can be obtained.

In the present invention, the following toners (a) to (e) are used.
(A) The toner contains 0.5 to 30% by mass of a low softening point substance.
(B) The weight average molecular weight (Mw) in the molecular weight distribution measured by gel permeation chromatography (GPC) of the tetrahydrofuran (THF) soluble content of the toner is 10,000 to 1,000,000, and the weight average The ratio (Mw / Mn) of molecular weight (Mw) to number average molecular weight (Mn) is 3 to 20,
(C) The insoluble content of the toner by Soxhlet extraction with a tetrahydrofuran solvent is 3 to 30% by mass.
(D) storage elastic modulus at a temperature of 50 ° C. of the toner (G _'50) and a storage modulus at a temperature 100 ° C. of the toner (G' ratio of _{100) (G '50 / G} ' 100) is 5,000～70 , 000,
(E) The storage elastic modulus (G ′ ₁₅₀ ) of the toner at a temperature of 150 ° C. is 1 × 10 ³ to 1 × 10 ⁵ (dN / m ² ).
It is characterized by satisfying. Each configuration will be described below.

  (A) The toner of the present invention contains 0.5 to 30% by mass of a low softening point substance.

  Examples of the low softening point substance used in the toner of the present invention include paraffin wax, polyolefin wax, modified products thereof (for example, oxides and grafted products), higher fatty acids and metal salts thereof, amide waxes, and ketones. Examples of such waxes include ester waxes, and amide waxes and ester waxes are preferred when used in color toners because high crystallinity impedes OHP permeability.

  When the blending amount of the low softening point material is less than 0.5% by mass, the effect of preventing offset tends to be reduced, and when it exceeds 30% by mass, the anti-blocking effect is reduced and the anti-offset effect tends to be adversely affected. In particular, in the case of a polymerized toner manufacturing method, a toner having a wide particle size distribution tends to be generated.

  The low softening point substance used in the present invention has a weight average molecular weight (Mw) to number average molecular weight (Mn) ratio (Mw / Mn) of 1 in the molecular weight distribution measured by GPC (gel permeation chromatography). It is preferable that it is 0.0-1.5. The closer the Mw / Mn value of the low softening point material is to 1.0, the sharper the molecular weight distribution. Specifically, it exhibits good melting characteristics when heat is applied during fixing, quickly exudes to the toner surface, and shows good fixing characteristics. Thus, a synergistic effect can be obtained by combining with the control of the material on the toner surface described above. On the other hand, if Mw / Mn is larger than 1.5, the low softening point substance is slowly oozed onto the toner surface, and the fixing characteristics are deteriorated.

  The molecular weight of the low softening point substance is measured by GPC under the following conditions.

[GPC measurement conditions]
Apparatus: GPC-150C (Waters)
Column: GMH-HT 30 cm 2 series (manufactured by Tosoh Corporation)
Temperature: 135 ° C
Solvent: o-dichlorobenzene (0.1% ionol added)
Flow rate: 1.0 ml / min
Sample: 0.4 ml injection of 0.15% sample A molecular weight calibration curve prepared from a monodisperse polystyrene standard sample is used to calculate the molecular weight of the sample. Furthermore, it calculates by converting into polyethylene by the conversion formula derived from the Mark-Houwink viscosity formula.

  (B) The toner of the present invention has a weight average molecular weight (Mw) in a molecular weight distribution measured by GPC of tetrahydrofuran (THF) soluble content of 10,000 to 1,000,000, and the weight average molecular weight (Mw) ) And the number average molecular weight (Mn) (Mw / Mn) is 3-20.

  Here, a method for measuring the molecular weight distribution of the THF soluble content of the toner is shown below.

[Method for measuring molecular weight distribution of THF-soluble matter]
The binder resin is put in tetrahydrofuran (THF) and allowed to stand for several hours, and then shaken well and mixed well with THF (until the resin is united), and left to stand for 12 hours or more. At this time, the standing time in THF is set to be 24 hours or longer. Thereafter, the sample is processed through a filter (pore size 0.45 to 0.5 μm, for example, “Myshor Disc H-25-5” manufactured by Tosoh Corporation, “Excro Disc 25CR” manufactured by Gelman Science Japan Co., Ltd., etc.). This is used as a GPC sample. The resin concentration is adjusted so that the resin component is 0.5 to 5 mg / ml.

The molecular weight distribution by GPC of the THF soluble component of the binder resin is measured by the following method. The column is stabilized in a 40 ° C. heat chamber, and THF as a solvent is allowed to flow through the column at this temperature at a flow rate of 1 ml per minute, and about 100 μl of the THF sample solution is injected and measured. In measuring the molecular weight of a sample, the molecular weight distribution of the sample is calculated from the relationship between the logarithmic value of a calibration curve prepared from several types of monodisperse polystyrene standard samples and the number of counts. As a standard polyester sample for preparing a calibration curve, for example, one having a molecular weight of about 10 ² to 10 ⁷ manufactured by Tosoh Corporation or Showa Denko is used, and at least about 10 standard polystyrene samples are suitably used. is there. An RI (refractive index) detector is used as the detector. As the column, it is preferable to combine a plurality of commercially available polystyrene gel columns. For example, a combination of shodex GPC KF-801, 802, 803, 804, 805, 806, 807, 800P manufactured by Showa Denko, A combination of TSKgel G1000H (HXL), G2000H (HXL), G3000H (HXL), G4000H (HXL), G5000H (HXL), G6000H (HXL), and G7000H (HXL) TSKguardcolumn is given.

  In particular, the column structure is preferably a combination of A-801, 802, 803, 804, 805, 806 and 807 manufactured by Showa Denko KK.

  (C) In the present invention, when the insoluble content (hereinafter referred to as “THF insoluble content”) of the toner by Soxhlet extraction with a THF solvent is 3 to 30% by mass, the gloss is maintained while maintaining the low-temperature fixability and the OHP permeability. Degree uniformity can be achieved.

  Here, a method for measuring the THF-insoluble matter is shown below.

[Measurement of THF-insoluble matter]
The THF-insoluble content refers to the mass ratio of the ultra-high polymer component (substantially crosslinked polymer) that has become insoluble in the THF solvent in the resin composition in the toner. The THF-insoluble content is defined as a value measured as follows.

A toner sample of 0.5 to 1.0 g is weighed (W ₁ g), put into a cylindrical filter paper (for example, No. 86R manufactured by Toyo Filter Paper), subjected to a Soxhlet extractor, and extracted for 6 hours using 100 to 200 ml of THF as a solvent. After evaporating the soluble component extracted with the THF solvent, it is vacuum-dried at 100 ° C. for several hours, and the amount of the THF-soluble resin component is weighed (W ₂ g). The mass of a component insoluble in THF such as a pigment in the toner is defined as (W ₃ g). The THF-insoluble content can be obtained from the following formula.

  When the THF-insoluble content of the toner is less than 3% by mass, the toner melt viscosity becomes too low when the fixing speed is low or double-sided fixing, the glossiness changes greatly, and high temperature offset tends to occur. On the other hand, if the THF-insoluble content of the toner exceeds 30% by mass, the toner will be incompletely melted even if sufficient heat is applied, resulting in poor color mixing and OHP permeability.

(D) In the present invention, the storage elastic modulus at a temperature of 50 ° C. of the toner (G _'50) and a storage modulus at a temperature 100 ° C. of the toner (G' ratio of _{100) (G '50 / G} ' 100) is By being 5,000-70,000, favorable low-temperature fixability is obtained. Here, the measuring method of storage elastic modulus (viscoelastic property) is shown below.

[Measurement of viscoelastic properties of toner]
Measurement is performed using a viscoelasticity measuring device (rheometer) “RDA-II type” (manufactured by Rheometrics).
Measuring jig: A parallel plate having a diameter of 7.9 mm is used when the elastic modulus is high, and a parallel plate having a diameter of 25 mm is used when the elastic modulus is low.
Measurement sample: Toner is heated and melted and molded into a cylindrical sample having a diameter of about 8 mm and a height of 1.5 to 5 mm, or a disk sample having a diameter of about 25 mm and a height of 1.5 to 3 mm.
Measurement frequency: 6.28 radians / second Measurement strain setting: The initial value is set to 0.1%, and measurement is performed in automatic measurement mode.
Sample extension correction: Adjust in automatic measurement mode.
Measurement temperature: The temperature is raised from 5 ° C. to 160 ° C. at a rate of 2 ° C. per minute.

The value of G ′ ₅₀ / G ′ ₁₀₀ indicates the melting characteristics of the toner when heat is applied, and it can be said that the larger the value, the sharper the melt.

In the present invention, if the value of G ′ ₅₀ / G ′ ₁₀₀ is less than 5,000, the toner melting is slow, and therefore, particularly when the process speed of the fixing device is high, fixing failure is likely to occur. When the value of G ′ ₅₀ / G ′ ₁₀₀ exceeds 70,000, the toner melts quickly, so that glossiness changes and offsets are likely to occur during double-sided printing.

(E) The toner of the present invention has a storage elastic modulus (G ′ ₁₅₀ ) at a temperature of 150 ° C. of 1 × 10 ³ to 1 × 10 ⁵ (dN / m ² ). From the viewpoint of sex. If the value of G ′ ₁₅₀ is smaller than 1 × 10 ³ , a change in glossiness at the front and rear ends and a change in glossiness on the front and back sides during double-sided printing are large and a stable image cannot be obtained. Also, if the value of G ′ ₁₅₀ is greater than 1 × 10 ⁵ , the change in gloss level is small even when the temperature of the fixing device changes or the process speed is changed, but the toner is not fully melted and OHP is transmitted. It is difficult to correspond to the mode that is not satisfied with the characteristics or outputs high gloss.

  Furthermore, the present inventors, when using the toner of the present invention in a printer or color printer, psychologically consider the fact that if the gloss of characters, graphs, and color images is too high, the image quality is rather poor. In addition to the viscoelastic characteristics as described above, the toner can be used to provide a toner that can give an image having a stable gloss or a full color image without causing fatigue even when many sheets are viewed. It has been found that it is desirable to have a melt index of a specific range.

  This is because it is difficult to judge the behavior of the toner, which is a composite of various functional substances, based only on the physical properties and addition amount of the material substance, and the gel content (insoluble content) and non-gel content of the binder resin. In view of (soluble component), it can be evaluated as a complex of release agent.

  That is, in the present invention, by setting the toner melt index (MI; temperature 135 ° C., load 2.2 kg) in 10 minutes to 1 to 40 (g / 10 minutes), the low temperature fixability is not impaired. It is possible to obtain a stable image having a low glossiness that does not cause fatigue even when a large number of images are viewed. When the MI value of the toner is less than 1, the fixed image has a low glossiness but is inferior in low-temperature fixability and OHP permeability. When the MI value of the toner exceeds 40, the glossiness is too high and the image quality is psychologically worse.

  Here, a method for measuring the MI value of the toner is described below.

[Melt index measurement]
The melt index indicates a discharge amount in 10 minutes at an arbitrary temperature and load. In this invention, it is set as the value measured on condition of the following. This basically conforms to the “JLS standard K-7210”.

  A “semi-automatic 2-A melt index” (Toyo Seiki Co. Ltd) is used as a measuring apparatus. An orifice having a hollow inner diameter of 2.095 mm is put, and the temperature is adjusted to 125 ° C. in advance, and 3 to 8 g of a toner sample is weighed and put therein. At this time, set the metal piston while being careful not to enter air bubbles, and keep the temperature for 5 minutes or more. Thereafter, measurement is performed while applying a constant load so that the total of the piston and the weight is 5 kg. The measurement may be performed at an arbitrary time and converted to a discharge amount of 10 minutes.

  In the present invention, it is preferable that the methanol wettability half value of the toner base particles is 13 to 50%. When the methanol wettability half-value is less than 13%, the abundance of the low softening point substance on the toner surface is low, and the low-temperature fixability is not satisfactory. If it exceeds 50%, the amount of low softening point substance on the toner surface is large and the low-temperature fixability is good. However, when the fixing temperature is high, the resin and the low softening point substance are separated. Is not preferable because sufficient hot offset resistance cannot be exhibited.

  Here, the toner base particles mean colored particles before the external addition processing of fine particles. In addition, the methanol wettability half-value refers to the point at which the transmittance is measured by methanol titration used when measuring the degree of methanol hydrophobization, and the point at which the sample is all sunk, that is, the point at which the transmittance is minimized ( The point is defined as the volume of methanol used at the time when the transmittance reaches the middle of the transmittance before the sample addition and the transmittance before the sample addition.

  In the present invention, the methanol wettability half value is determined as follows.

[Measurement of methanol wettability half-value]
Weigh out 60 cm ³ of ion-exchanged water in a 200 cm ³ beaker. 0.0100 g of a sample is placed in a methanol aqueous solution, and the transmittance is measured using a powder wettability tester “WET-100P” (manufactured by Reska Co., Ltd.). For the transmittance measurement, a semiconductor laser having an output of 3 mW and a wavelength of 780 nm was used. Measurement conditions are a stirrer rotation speed: 5 sec ⁻¹ and a methanol flow rate: 0.8 cm ³ / min. When the transmittance before addition of the sample is I ₀ (100%), the transmittance at the time of measurement is I (%), and the minimum measured transmittance is I _min (%), the methanol wettability half-value is the transmittance I Is I = 100 − {(I ₀ −I _min ) / 2} (%)
This is expressed as the volume% of methanol used.

Here, the volume% of methanol used at the transmittance I _min has the same meaning as the degree of hydrophobicity of methanol, and this point is defined as the end point of methanol wettability.

  In the present invention, the contact angle with water after heating the toner base particles at 100 ° C. for 2 minutes is preferably 102 to 130 °. When the contact angle is less than 102 °, the amount of low softening point substance on the toner surface is low and the low-temperature fixability is not satisfactory. When the contact angle exceeds 130 °, the low softening point substance on the toner surface is not satisfactory. However, when the temperature is high, the resin and the low softening point substance are separated, and sufficient hot offset resistance cannot be exhibited, which is not preferable. Here, the toner base particles mean the toner base particles described in the previous half-value of methanol wettability. The contact angle is measured by the following method.

(Measurement of contact angle)
Measuring device: FACE contact angle measuring device (manufactured by Kyowa Interface Chemical Co., Ltd.)
Measurement temperature: 23-25 ° C
Measurement humidity: Relative humidity 40-60%
Sample preparation: Approximately 10 g of toner is compression molded at a pressure of 1.96 × 10 ⁷ Pa for 2 minutes to produce a disk-shaped sample having a diameter of 25 mm and a thickness of about 3 mm. At that time, the aluminum ring is sandwiched between two OHP sheets (Canon black-and-white copying machine sheet such as TYPE-D sold by Canon USA) so that the surface of the measurement surface is uniform. Good to create. This sample is put in an oven preliminarily adjusted to 100 ° C. for 2 minutes. Take out and measure after cooling. Incidentally, the measurement using the ion-exchanged water or commercially available purified water to 10 times the contact angle with the average value of cut remaining 8 data One not a vertical one data measured with the contact angle of the toner for each sample.

  In the present invention, it is preferable that the average circularity is 0.950 to 1.0 in the particle size distribution by the equivalent circle diameter measured by the flow type particle image analyzer of toner. When the average circularity is 0.950 to 1.0, the surface of the print surface is uniform in a meteorite shape even in a low gloss image preferred for business use (that is, fixing without completely dissolving the toner). The diffuse reflection can be minimized. Further, it is possible to improve the transparency and minimize the change in hue angle even in the transmitted light of the transparency image.

  On the other hand, when the average circularity is less than 0.950, the surface of the surface where the toner shape remains is rough, so that the transmittance is lowered and the hue angle is changed due to irregular reflection. In addition, due to the irregular toner, the filling property in an unfixed state before passing through the fixing roller is low, and in a fixing configuration in which low glossiness is achieved, bubbles remain in the inside and the OHP permeability is lowered. Black toner is also less likely to cause offset because of its low fillability.

  Here, the flow-type particle image measuring device is a device that statistically performs image analysis of particle imaging, and the average circularity is calculated by the arithmetic average of the circularity obtained by the following equation using the device. . The equivalent circle diameter is the diameter of a circle having the same area as the area of the measured two-dimensional image of the particles.

  Circularity = Perimeter of equivalent circle / perimeter of particle projection image

  In the above equation, the perimeter of the particle projection image is the length of the contour line obtained by connecting the edge points of the binarized particle image, and the perimeter of the equivalent circle is the binarized particle This is the length of the outer circumference of a circle having the same area as the image.

(Measurement of particle size distribution)
“FPIA-1000” (manufactured by Toa Medical Electronics Co., Ltd.) is used as a flow type particle image measuring apparatus.

  As a measurement method, a sample to be measured was added to 10 ml (20 ° C.) of a solution prepared by adding 0.1 to 0.5% by mass of a surfactant (preferably “Contaminone” manufactured by Wako Pure Chemical Industries, Ltd.) to ion exchange water. 0.02 g was added and dispersed uniformly to prepare a sample dispersion.

  As a means for dispersion, an ultrasonic disperser “UM-50” manufactured by SMT Co., Ltd. (vibrator is 5φ titanium alloy chip) is used, the dispersion time is 5 minutes, and the temperature of the dispersion medium is 40 ° C. or higher. It cooled so that it might not become.

  In the measurement, the range of 0.60 to 400 μm is divided into 226 channels, and in the actual measurement, particles are measured in a range where the equivalent circle diameter is 0.60 μm or more and less than 159.21 μm.

  The toner of the present invention contains at least a binder resin and a colorant in addition to the above low softening point substance.

  Examples of the binder resin used in the toner of the present invention include homopolymers of styrene such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene, and substitutes thereof; styrene-p-chlorostyrene copolymers, styrene. -Vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer Polymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer Styrenic copolymer such as coalescence Polyvinyl chloride; Phenol resin; Naturally modified phenolic resin; Naturally modified maleic acid resin; Acrylic resin; Methacrylic resin; Polyvinyl acetate; Silicone resin; Polyester resin; Polyurethane resin; Terpene resin; coumarone indene resin; petroleum resin can be used. Preferred binder materials include styrene copolymers or polyester resins.

  Examples of the comonomer for the styrene monomer of the styrene copolymer include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, methacrylic acid. Acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile, monocarboxylic acid having a double bond such as acrylamide or a substituted product thereof; for example, maleic acid, butyl maleate, Dicarboxylic acids having a double bond such as methyl maleate and dimethyl maleate and substituted products thereof; for example, vinyl esters such as vinyl chloride, vinyl acetate and vinyl benzoate; Ethylene olefins such as len; vinyl monomers such as vinyl methyl ketone, vinyl hexyl ketone; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether; Are used alone or in combination of two or more.

  The styrenic polymer or styrenic copolymer may be cross-linked, or may be a mixed resin of a cross-linked resin and a non-cross-linked resin.

  As the crosslinking agent for the binder resin, a compound having two or more polymerizable double bonds may be mainly used. For example, aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; carboxylic acid esters having two double bonds such as ethylene glycol diacrylate, ethylene glycol dimethacrylate and 1,3-butanediol dimethacrylate; , Divinyl aniline, divinyl ether, divinyl sulfide, divinyl sulfone and the like; and compounds having three or more vinyl groups are used alone or as a mixture.

  As addition amount of a crosslinking agent, 0.001-10 mass parts is preferable with respect to 100 mass parts of polymerizable monomers.

  As the colorant used in the toner of the present invention, carbon black was used as the black colorant, and the following yellow / magenta / cyan colorants, and the yellow / magenta / cyan colorant were used to adjust the color to black. Things are used.

  As the yellow colorant, compounds represented by condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, allylamide compounds, and the like are used. Specifically, C.I. I. Pigment Yellow 3, 7, 10, 12-15, 17, 23, 24, 60, 62, 74, 75, 83, 93-95, 99, 100, 101, 104, 108-111, 117, 123, 128, 129, 138, 139, 147, 148, 150, 166, 168, 169, 177, 179, 180, 181, 183, 185, 191, 192, 170, 199, etc. are preferably used. In addition, C.I. I. Solvent Yellow 33, 56, 79, 82, 93, 112, 162, 163, C.I. I. Disperse Yellow 42, 64, 201, 211 etc. are mentioned. If necessary, yellow pigments and dyes may be used alone, or pigments and dyes may be used in combination.

  As the magenta colorant, condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinones, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, perylene compounds, and the like are used. Specifically, C.I. I. Pigment Red 2, 3, 5, 6, 7, 23, 48: 2, 48: 3, 48: 4, 57: 1, 81: 1, 122, 146, 166, 169, 177, 184, 185, 202, 206, 220, 221, 254 and C.I. I. Pigment Violet 19 and the like are particularly preferable. If necessary, magenta pigments and dyes may be used alone or in combination with pigments and dyes.

  As the cyan colorant used in the present invention, copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds, basic dye lake compounds, and the like can be used. Specifically, C.I. I. Pigment Blue 1, 7, 15, 15: 1, 15: 2, 15: 3, 15: 4, 60, 62, 66 and the like can be used particularly preferably. If necessary, cyan pigments and dyes may be used alone, or pigments and dyes may be used in combination.

  These colorants can be used alone or mixed and further used in the form of a solid solution. The colorant of the present invention is selected from the viewpoints of hue angle, saturation, brightness, weather resistance, OHP transparency, and dispersibility in the toner. The colorant is added in an amount of 1 to 20 parts by mass with respect to 100 parts by mass of the resin.

  The toner of the present invention may further contain a charge control agent.

  For controlling the toner to be negatively charged, for example, an organometallic compound and a chelate compound are effective, and there are a monoazo metal compound, an acetylacetone metal compound, an aromatic hydroxycarboxylic acid, and an aromatic dicarboxylic acid-based metal compound. Other examples include aromatic hydroxycarboxylic acids, aromatic mono- and polycarboxylic acids and their metal salts, anhydrides, esters, and phenol derivatives such as bisphenol. Further, urea derivatives, metal-containing salicylic acid compounds, metal-containing naphthoic acid compounds, boron compounds, quaternary ammonium salts, calixarene, silicon compounds, styrene-acrylic acid copolymers, styrene-methacrylic acid copolymers, styrene- An acrylic-sulfonic acid copolymer, a nonmetal carboxylic acid compound, etc. are mentioned. Further, a resin having the charge control compound pendant may be internally added to the toner.

  Examples of toners that are controlled to be positively charged include, for example, modified products of nigrosine and fatty acid metal salts, guanidine compounds, imidazole compounds, tributylbenzylammonium-1-hydroxy-4-naphthosulfonate, tetrabutylammonium tetrafluoro, and the like. Quaternary ammonium salts such as borates, and onium salts such as phosphonium salts and analogs thereof, and lake pigments thereof, triphenylmethane dyes and lake lake pigments (the rake agents include phosphotungstic acid, phosphomolybdic acid Phosphotungstomolybdic acid, tannic acid, lauric acid, gallic acid, ferricyanide, ferrocyanide, etc.), higher fatty acid metal salts; dibutyltin oxide, dioctyltin oxide, dicyclohexyltin oxide, etc. Organotin oxide; dibutyl tin borate, dioctyl tin borate, diorgano tin borate such as dicyclohexyl tin borate; can be used in combination singly, or two or more kinds. Among these, a charge control agent such as a nigrosine-type quaternary ammonium salt is particularly preferably used. Further, a resin having the charge control compound pendant may be internally added to the toner.

  These charge control agents may be used in an amount of 0.01 to 20 parts by mass (more preferably 0.5 to 10 parts by mass) with respect to 100 parts by mass of the resin component.

  Examples of the method for producing the toner of the present invention include a method for producing a toner by mechanically or thermally spheroidizing toner particles produced by a pulverization method, and a method for producing a toner directly by a polymerization method. It is done.

  In the present invention, a method for producing a pulverized toner is obtained by sufficiently mixing a binder resin, a low softening point substance, a colorant, and, if necessary, a charge control agent and other additives with a mixer such as a Henschel mixer or a ball mill. The obtained mixture is melt-kneaded using a heat kneader such as a heating roll, a kneader or an extruder, and the low softening point substance and the colorant are dispersed or dissolved while the resin components are mixed with each other; The product can be cooled and solidified, and then pulverized and classified to obtain a toner.

  Further, if necessary, the toner and the desired additive can be sufficiently mixed with a mixer such as a Henschel mixer to obtain the toner used in the present invention.

  In the present invention, a method for producing a polymerized toner includes a method in which a molten mixture is atomized into air using a disk or a multi-fluid nozzle to obtain a spherical toner, a method in which a toner is directly produced by using a suspension polymerization method, and a monomer. Is an emulsification typified by a dispersion polymerization method that directly produces a toner using an aqueous organic solvent in which the resulting polymer is insoluble or a soap-free polymerization method that produces a toner by directly polymerizing in the presence of a water-soluble polar polymerization initiator. It is possible to produce a toner using a polymerization method and a hetero-aggregation method in which primary polar emulsion polymer particles are prepared in advance and then polar particles having opposite charges are added and associated.

  However, in the dispersion polymerization method, the obtained toner shows a very sharp particle size distribution, but the manufacturing apparatus is used from the viewpoint of the processing of the waste solvent and the flammability of the solvent due to the narrow selection of materials to be used and the use of organic solvents. Complicated and complicated. An emulsion polymerization method typified by soap-free polymerization is effective because the particle size distribution of the toner is relatively uniform. However, when the used emulsifier and initiator terminal are present on the toner particle surface, the environmental characteristics are easily deteriorated.

  Therefore, in the present invention, a suspension polymerization method under normal pressure or under pressure, which can obtain a fine particle toner having a sharp particle size distribution relatively easily, is particularly preferable. A so-called seed polymerization method in which a monomer is further adsorbed to the polymer particles once obtained and then polymerized using a polymerization initiator can also be suitably used in the present invention.

  When the direct polymerization method is used in the toner production method of the present invention, a polymerizable monomer composition containing at least a polymerizable monomer, a low softening point substance, and a colorant is polymerized in a solvent solution in the presence of a polymerization initiator. To do. A specific manufacturing method is shown below.

  A polymerizable monomer composition in which a low softening point substance, a colorant, a polymerization initiator, a charge control agent and other additives are added to the monomer, and dissolved or dispersed uniformly by a homogenizer, ultrasonic disperser, etc. The product is dispersed in an aqueous phase containing a dispersion stabilizer by a usual stirrer, homomixer, homogenizer or the like. Preferably, granulation is performed by adjusting the stirring speed and time so that the monomer droplets have a desired toner particle size. Thereafter, stirring may be performed to such an extent that the particle state is maintained and the sedimentation of the particles is prevented by the action of the dispersion stabilizer. Polymerization is carried out at a polymerization temperature of 40 ° C. or higher, generally 50 to 90 ° C. In addition, the temperature may be raised in the latter half of the polymerization reaction, and further, in order to remove unreacted polymerizable monomers and by-products that cause odor when fixing the toner, the latter half of the reaction or the completion of the reaction. A part of the aqueous medium may be distilled off later. After completion of the reaction, the produced toner particles are recovered by washing and filtration and dried. In the suspension polymerization method, it is usually preferable to use 300 to 3000 parts by mass of water as a dispersion medium with respect to 100 parts by mass of the monomer system.

  A more preferable toner used in the present invention is a toner tomographic surface measurement method using a transmission electron microscope (TEM), which is manufactured using a direct polymerization method in which a low softening point substance is encapsulated in an outer shell resin layer. It is a thing. From the viewpoint of fixing properties, it is necessary to include a large amount of a low softening point substance in the toner. Therefore, it is necessary to encapsulate the necessary low softening point substance in the outer shell resin. If the toner cannot be encapsulated, it will not be finely pulverized unless special freeze pulverization is used in the pulverization process, resulting in only a wide particle size distribution, and toner fusion to the device will also occur. That's bad. In freeze pulverization, the apparatus becomes complicated to prevent dew condensation on the apparatus, and if the toner absorbs moisture, the workability of the toner is reduced, and it is necessary to add a drying process. As a specific method of encapsulating the low softening point substance, the polarity of the material in the aqueous medium is set smaller than that of the main monomer, and the small softening point substance or a small amount of a resin having a large polarity or a simple substance is used. By adding a monomer, a toner having a so-called core-shell structure in which a low softening point substance is coated with an outer shell resin can be obtained. Toner particle size distribution control and particle size control can be done by changing the type and amount of a poorly water-soluble inorganic salt or protective colloidal dispersant and the amount of mechanical equipment such as rotor speed, number of passes, stirring blades, etc. The predetermined toner of the present invention can be obtained by controlling the stirring conditions such as the shape, the container shape, or the solid content concentration in the aqueous solution.

  In the present invention, as a specific method for measuring the tomographic plane of the toner, there are four cured products obtained by sufficiently dispersing the toner in a room temperature curable epoxy resin and curing it in an atmosphere at a temperature of 40 ° C. for two days. After staining with ruthenium trioxide and, if necessary, osmium tetroxide, a flaky sample was cut out using a microtome equipped with diamond teeth, and the tomographic morphology of the toner was measured using a transmission electron microscope (TEM). In the present invention, it is preferable to use a ruthenium tetroxide dyeing method in order to provide a contrast between materials by utilizing a slight difference in crystallinity between the low softening point substance used and the resin constituting the outer shell.

  A monofunctional polymerizable monomer or a polyfunctional polymerizable monomer can be used as the vinyl polymerizable monomer capable of radical polymerization, which is used when a toner is produced by a polymerization method.

  Monofunctional polymerizable monomers include styrene, α-methyl styrene, β-methyl styrene, o-methyl styrene, m-methyl styrene, p-methyl styrene, 2,4-dimethyl styrene, pn-butyl. Styrene, p-tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, p-methoxy styrene, p -Styrene polymerizable monomers such as phenyl styrene; methyl acrylate, ethyl acrylate, n-propyl acrylate, iso-propyl acrylate, n-butyl acrylate, iso-butyl acrylate, tert-butyl acrylate, n-amyl acrylate, n -Hexyl acrylate, 2-ethylhexyl acrylate Acrylic polymerizable monomers such as relate, n-octyl acrylate, n-nonyl acrylate, cyclohexyl acrylate, benzyl acrylate, dimethyl phosphate ethyl acrylate, dibutyl phosphate ethyl acrylate, 2-benzoyloxyethyl acrylate; methyl methacrylate, ethyl Methacrylate, n-propyl methacrylate, iso-propyl methacrylate, n-butyl methacrylate, iso-butyl methacrylate, tert-butyl methacrylate, n-amyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, n-nonyl Methacrylate, diethyl phosphate ethyl methacrylate, dibutyl phosphate ethyl Methacrylic polymerizable monomers such as methacrylate; methylene aliphatic monocarboxylic acid esters; vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate, vinyl butyrate, vinyl benzoate, vinyl formate; vinyl methyl ether, Examples thereof include vinyl ethers such as vinyl ethyl ether and vinyl isobutyl ether; vinyl polymerizable monomers such as vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and vinyl isopropyl ketone.

  As polyfunctional polymerizable monomers, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, tripropylene glycol Diacrylate, polypropylene glycol diacrylate, 2,2'-bis [4- (acryloxy-diethoxy) phenyl] propane, trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol Dimethacrylate, tetraethylene glycol dimethacrylate, polyethylene glycol Dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, polypropylene glycol dimethacrylate, 2,2′-bis [4- (methacryloxy-diethoxy) phenyl] propane, Examples include 2,2′-bis [4- (methacryloxy / polyethoxy) phenyl] propane, trimethylolpropane trimethacrylate, tetramethylolmethane tetramethacrylate, divinylbenzene, divinylnaphthalene, and divinyl ether.

  The monofunctional polymerizable monomers can be used alone or in combination of two or more, and a monofunctional polymerizable monomer and a polyfunctional polymerizable monomer can be used in combination. Moreover, it is also possible to use the said polyfunctional polymerizable monomer as a crosslinking agent.

  In the present invention, it is preferable to use a polar resin together in order to form a core-shell structure in the toner. Examples of polar resins such as polar polymers and polar copolymers that can be used in the present invention are given below.

  Polar resins include polymers of nitrogen-containing monomers such as dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate, or copolymers of nitrogen-containing monomers and styrene-unsaturated carboxylic acid esters; nitriles such as acrylonitrile Monomer; Halogen-containing monomer such as vinyl chloride; Unsaturated carboxylic acid such as acrylic acid and methacrylic acid; Unsaturated dibasic acid; Unsaturated dibasic acid anhydride; Polymer of nitro monomer or Examples thereof include copolymers of styrene monomers and polyesters; epoxy resins. More preferred are styrene and (meth) acrylic acid copolymers, maleic acid copolymers, saturated or unsaturated polyester resins, and epoxy resins.

  Examples of the polymerization initiator include 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1′-azobis (cyclohexane-1-carbonitrile). ), 2,2′-azobis-4-methoxy-2,4-dimethylvaleronitrile, azobisisobutyronitrile and other azo or diazo polymerization initiators; benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydro Peroxide, tert-butyl hydroperoxide, di-tert-butyl peroxide, dicumyl peroxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide, 2,2-bis (4,4-tert-butylperoxycyclohexyl) propane, tris- And peroxide initiators, such as tert- butylperoxy) triazine, polymeric initiator having a peroxide in the side chain, potassium persulfate, persulfates such as ammonium persulfate, hydrogen peroxide, etc. are used.

  The polymerization initiator is preferably added in an amount of 0.5 to 20 parts by mass per 100 parts by mass of the polymerizable monomer, and may be used alone or in combination.

  Moreover, in order to control molecular weight in this invention, you may add a well-known crosslinking agent and a chain transfer agent, As a preferable addition amount, it is 0.001-15 mass parts.

  In the present invention, any suitable stabilizer is used for the dispersion medium used in the production of the polymerization toner by emulsion polymerization, dispersion polymerization, suspension polymerization, seed polymerization, polymerization method using heteroaggregation method, or the like. To do. For example, as an inorganic compound, tricalcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, calcium carbonate, magnesium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate, barium sulfate , Bentonite, silica, alumina and the like. Organic compounds include polyvinyl alcohol, gelatin, methylcellulose, methylhydroxypropylcellulose, ethylcellulose, sodium salt of carboxymethylcellulose, polyacrylic acid and its salts, starch, polyacrylamide, polyethylene oxide, nonionic or ionic surfactants, etc. Is done.

  In the case of using the emulsion polymerization method and the heteroaggregation method, an anionic surfactant, a cationic surfactant, a zwitterionic surfactant and a nonionic surfactant are used. These stabilizers are preferably used in an amount of 0.2 to 30 parts by mass with respect to 100 parts by mass of the polymerizable monomer.

  Among these stabilizers, when an inorganic compound is used, a commercially available one may be used as it is, but in order to obtain fine particles, the inorganic compound may be produced in a dispersion medium.

  Moreover, you may use 0.001-0.1 mass part surfactant for fine dispersion of these stabilizers. This is to promote the intended action of the dispersion stabilizer, and specific examples thereof include sodium dodecylbenzene sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, and lauric acid. Examples thereof include sodium, potassium stearate, calcium oleate and the like.

  The toner of the present invention can usually be used for one-component and two-component developers. When a non-magnetic toner containing no magnetic material is used as a one-component developer, there is a method in which a blade or a roller is used to forcibly charge the toner by a developing sleeve, and the toner is attached to the sleeve and conveyed. is there.

  Next, a preferred image forming apparatus to which the toner and the image forming method of the present invention are applied will be described.

(1) Image Forming Apparatus Example FIG. 1 is a schematic configuration diagram of an electrophotographic printer as an example of an image forming apparatus. In the figure, reference numeral 1 denotes a photosensitive drum (image carrier) made of an organic photosensitive member or an amorphous silicon photosensitive member, which is rotationally driven in the direction of an arrow at a predetermined process speed (peripheral speed). The photosensitive drum 1 is uniformly charged with a predetermined polarity and potential by a charging device 2 such as a charging roller in the course of rotation. Next, the charging processing surface is subjected to scanning exposure processing of target image information by laser light 3 output from a laser optical box (laser scanner) 8. The laser optical box 8 outputs a laser beam 3 modulated (on / off) corresponding to a time-series electric digital pixel signal of target image information from an image signal generation device such as an image reading device (not shown), and rotates. An electrostatic latent image corresponding to the target image information scanned and exposed is formed on the surface of the photosensitive drum 1 to be scanned.

  Next, the electrostatic latent image is visualized as a toner image on the photosensitive drum 1 by the developing device 4 to which an appropriate development potential difference is given to the electrostatic latent image. The toner image is transferred onto the surface of the recording material P fed at a predetermined timing from a sheet feeding unit (not shown) in a transfer unit which is a contact nip portion between the photosensitive drum 1 and the transfer roller 6. The transfer roller 6 transfers a toner image from the photosensitive drum 1 surface side to the recording material P side by supplying a charge having a polarity opposite to that of the toner from the back surface of the recording material P.

  The recording material P that has passed through the transfer portion is separated from the surface of the photosensitive drum 1 and introduced into the heat fixing device 5, and is subjected to heat fixing processing of an unfixed toner image to be discharged as an image formed product outside the apparatus (not shown). It is discharged to the paper tray. The heat fixing device 5 will be described later.

  After the toner image is transferred to the recording material P, the photosensitive drum 1 is cleaned by the cleaner 7 after removal of residual residues such as transfer residual toner and paper dust.

  This apparatus can also execute a print mode for mono-color images other than black by using mono-color toner as toner to be filled in the cartridge. A double-sided image print mode or a multiple image print mode can also be executed. In the case of the double-sided image print mode, the recording material P on which the first side image has been printed out of the heat fixing device 5 is turned upside down through a recirculation conveyance mechanism (not shown) and sent again to the transfer unit. Upon receiving the toner image transfer, the image is again introduced into the heat fixing device 5 and undergoes toner image fixing processing on the two surfaces, whereby a double-sided image print is output.

  In the multiple image print mode, the recording material P printed with the first image that has exited the heat fixing device 5 is sent again to the transfer section through the recirculation conveyance mechanism (not shown) without being turned upside down. A second image transfer is received on the printed surface, and the image is again introduced into the heat-fixing device 5 and undergoes a second toner image fixing process, whereby a multiple image print is output.

  On the other hand, FIG. 2 is a schematic configuration diagram of an electrophotographic full-color printer as an example of another image forming apparatus.

  Reference numeral 11 denotes a photosensitive drum (image carrier) made of an organic photosensitive member or an amorphous silicon photosensitive member, which is rotationally driven in a direction indicated by an arrow at a predetermined process speed (peripheral speed). The photosensitive drum 11 is uniformly charged with a predetermined polarity and potential by a charging device 12 such as a charging roller in the course of rotation.

  Next, the charged surface is subjected to a scanning exposure process of target image information by a laser beam 13 output from a laser optical box (laser scanner) 20. The laser optical box 20 outputs a laser beam 13 that is modulated (ON / OFF) in accordance with a time-series electric digital pixel signal of target image information from an image signal generation device such as an image reading device (not shown), and rotates. An electrostatic latent image corresponding to target image information scanned and exposed on the surface of the photosensitive drum 11 is formed. A mirror 19 deflects the output laser light from the laser optical box 20 to the exposure position of the photosensitive drum 11.

  In the case of full-color image formation, scanning exposure / latent image formation is performed on a first color separation component image of a target full-color image, for example, a yellow component image, and the latent image is subjected to yellow development in the four-color developing device 14. The toner image is developed by the operation of the device 14Y. The toner image is transferred to the surface of the intermediate transfer drum 15 at the primary transfer portion T1 which is a contact portion (or proximity portion) between the photosensitive drum 11 and the intermediate transfer drum 15. The surface of the rotating photosensitive drum 11 after the transfer of the toner image to the surface of the intermediate transfer drum 15 is cleaned by the cleaner 17 after removal of adhesion residues such as transfer residual toner.

  The process cycle of charging, scanning exposure, development, primary transfer, and cleaning as described above includes the second color separation component image (for example, magenta component image, magenta developing unit 14M is activated) of the target full color image, and the third color. An intermediate transfer body is sequentially executed for each color separation component image of the separation component image (for example, cyan component image, cyan developing device 14C is activated) and the fourth color separation component image (for example, black component image, black developing device 14BK is activated). Four color toner images, a yellow toner image, a magenta toner image, a cyan toner image, and a black toner image, are sequentially superimposed and transferred onto the surface of the drum 15, and a color toner image corresponding to the target full-color image is synthesized and formed. .

  The intermediate transfer drum 15 has a middle resistance elastic layer and a high resistance surface layer on a metal drum, and is in contact with or close to the photosensitive drum 11 at the same peripheral speed as the photosensitive drum 11 in the direction of the arrow. And a bias potential is applied to the metal drum of the intermediate transfer drum 15 to transfer the toner image on the photosensitive drum 11 side to the surface of the intermediate transfer drum 15 by a potential difference from the photosensitive drum 11.

  The color toner image synthesized and formed on the surface of the rotary intermediate transfer drum 15 is transferred to the secondary transfer portion T2 at the secondary transfer portion T2 which is a contact nip portion between the rotary intermediate transfer drum 15 and the transfer roller 16. At T2, the image is transferred onto the surface of the recording material P fed from a paper supply unit (not shown) at a predetermined timing. The transfer roller 16 supplies a charge having a polarity opposite to that of the toner from the back surface of the recording material P, thereby sequentially transferring the combined color toner images sequentially from the surface of the intermediate transfer drum 15 to the recording material P side.

  The recording material P that has passed through the secondary transfer portion T2 is separated from the surface of the intermediate transfer drum 15, introduced into the heat fixing device 21, and subjected to heat fixing processing of an unfixed toner image as a color image formed product. Are discharged to a paper discharge tray (not shown). The heat fixing device 21 will be described later.

  The rotary intermediate transfer drum 15 after the color toner image has been transferred to the recording material P is cleaned by the cleaner 18 after removal of residual residues such as transfer residual toner and paper dust. The cleaner 18 is normally held in a non-contact state with the intermediate transfer drum 15 and is in contact with the intermediate transfer drum 15 during the secondary transfer of the color toner image from the intermediate transfer drum 15 to the recording material P. Retained.

  Also, the transfer roller 16 is always held in a non-contact state with the intermediate transfer drum 15 and is recorded on the intermediate transfer drum 15 during the secondary transfer of the color toner image from the intermediate transfer drum 15 to the recording material P. The contact state is maintained via the material P.

  This example apparatus can also execute a mono-color image print mode such as a monochrome image. A double-sided image print mode or a multiple image print mode can also be executed. In the double-sided image print mode, the recording material P on which the first-side image has been printed exiting the fixing device 100 is turned upside down via a recirculation conveyance mechanism (not shown) and sent again to the secondary transfer portion T2. Upon receipt of the toner image transfer on the surface, the image is again introduced into the fixing device 21 and undergoes toner image fixing processing on the two surfaces, whereby a double-sided image print is output.

  In the multiple image print mode, the recording material P after the first image printed out of the fixing device 21 is sent to the secondary transfer portion T2 again without being turned upside down via a recirculation conveyance mechanism (not shown). The second toner image is transferred to the surface on which the first image has been printed, and is again introduced into the fixing device 21 and undergoes the second toner image fixing process, whereby a multiple image print is output.

In the image forming method of the present invention, the toner carrying amount (basis weight; M / S) on the recording material is 0.80 dg / m ² or less in the case of monochromatic monocolor such as magenta, cyan, and yellow in addition to black toner. Is preferable, 0.7 dg / m ² or less is more preferable, and 0.6 dg / m ² or less is particularly preferable. When it exceeds 0.80 dg / m ² , it is difficult to clearly express the effect of the present invention.

  Next, the heat fixing device will be described.

(2) Heat-fixing device In the present invention, the heat-fixing device has a heating body fixed at a predetermined position and an elastic layer having a rubber hardness of 10 to 50 ° according to JIS-A that is in pressure contact with the heating body. A fixing belt, and a temperature detection unit. The temperature detection unit is brought into contact with the inner surface of the fixing belt to adjust the temperature, and the recording material is brought into close contact with the heating body through the fixing belt. A heat fixing device that heats and fixes the toner image on the recording material is used.

  FIG. 3 is a front view of an example of the heat fixing apparatus used in the present invention, FIG. 4 is a longitudinal sectional view thereof, and FIG. 6 is a transverse sectional view thereof. 3 and 4, a pressure roller 30 as a pressure member is made of a core metal 30a and a silicone rubber, a fluoro rubber, a fluoro resin, or the like, which is molded and coated concentrically around the core metal 30a in a roller shape. It consists of a heat-resistant / elastic material layer 30b, and both ends of the cored bar 30a are rotatably supported and supported between chassis side sheet metal (not shown) of the apparatus.

  A pressing force is applied to the pressurizing rigid stay 32 by contracting the pressurizing springs 35a and 35b between the both ends of the pressurizing rigid stay 32 and the spring receiving members 39a and 39b on the apparatus chassis side. . As a result, the lower surface of the belt guide member 31a and the upper surface of the pressure roller 30 are pressed against each other with the fixing belt 34 interposed therebetween, so that a fixing nip portion N having a predetermined width is formed.

  The pressure roller 30 is rotationally driven by a driving means (not shown). A rotational force acts on the fixing belt 34 by the frictional force between the pressure roller 30 and the outer surface of the fixing belt 34 due to the rotational driving of the pressure roller 30, and the inner surface of the fixing belt 34 is shown in FIG. The belt guide members 31a and 31b rotate around the belt guide members 31a and 31b at a peripheral speed substantially corresponding to the rotational peripheral speed of the pressure roller 30 while sliding in close contact with the lower surface of the good heat conducting member 40 at N.

  In the present invention, since a toner containing a low softening substance is used, it is not necessary to provide an oil application mechanism for preventing offset in the heat fixing device.

  The configuration of the heat fixing device which is one of the features of the present invention will be described more specifically.

(A) Heating body In the present invention, a ceramic heater is preferably used as the heating body, and more preferably an aluminum nitride ceramic heater.

(B) Fixing Belt FIG. 5 is a schematic diagram showing the layer structure of the fixing belt (34 in FIGS. 3, 4, and 6) used in the present invention. Such a fixing belt includes at least an elastic layer having a JIS-A rubber hardness of 10 to 50 °, and preferably includes a base layer 51, an elastic layer 52, and a release layer 53 as shown in FIG. Yes. The base layer 51 is composed of a metal belt or the like and serves as a heat generating layer. A primer layer (not shown) may be provided between each layer for adhesion between the base layer 51 and the elastic layer 52 and adhesion between the elastic layer 52 and the release layer 53. The fixing belt has a substantially cylindrical shape, a base layer 51 is disposed on the inner surface side, and a release layer 53 is on the outer surface side. Heat generated from the ceramic heater is transmitted to the base layer 51, and the heat heats the entire fixing belt through the elastic layer 52 and then the release layer 53, and the recording material P as a heated material passed through the fixing nip portion N. And the toner image formed on the recording material is heated and fixed.

  The base layer 51 may be a non-magnetic metal, but more preferably a metal such as a SUS alloy, nickel, iron, magnetic stainless steel, or cobalt-nickel alloy. The thickness is preferably 1 to 200 μm. If the thickness of the base layer 51 is smaller than 1 μm, the rigidity is low and it is difficult to endure the durability of a large number of sheets. On the other hand, if the base layer exceeds 200 μm, the rigidity becomes too high, and the flexibility becomes poor, so that it is not practical to use as a rotating body.

  If the hardness of the elastic layer 52 is too high, the unevenness of the recording material or the toner layer cannot be followed and image gloss unevenness occurs. On the other hand, if the hardness is too low, the OHT permeability is deteriorated, and the durability of the fixing device is extremely inferior. Therefore, the hardness of the elastic layer 52 is preferably 10 ° to 50 ° according to JIS-A.

  The elastic layer 52 is a material having good heat resistance and good thermal conductivity, such as silicone rubber, fluorine rubber, and fluorosilicone rubber. The elastic layer 52 may contain zinc oxide as a heat conductive material. The addition amount is preferably in the range of 20 to 60% by volume.

  The thickness of the elastic layer 52 is 100 to 500 μm in order to prevent uneven glossiness due to the fact that the heating surface (release layer 53) cannot follow the unevenness of the recording material or the unevenness of the toner layer when printing an image. preferable. If the thickness of the elastic layer 52 is less than 100 μm, the function as an elastic member is not exhibited, and the pressure distribution at the time of fixing becomes non-uniform, thereby sufficiently heating the unfixed toner of the secondary color particularly at the time of fixing a full color image. Not only fixing but also non-uniformity in the gloss of the fixed image cannot be achieved, and insufficient color mixing of the toner deteriorates due to insufficient melting, and a high-definition full-color image cannot be obtained. On the other hand, if the thickness of the elastic layer 52 exceeds 500 μm, the thermal conductivity at the time of fixing is hindered, and the thermal followability on the fixing surface is deteriorated, so that not only the quick start property is sacrificed but also the fixing unevenness. Is liable to occur, which is not preferable.

  For the release layer 53, a material having good release properties and heat resistance such as fluororesin, silicone resin, fluorosilicone rubber, fluororubber, silicone rubber, PFA, PTFE, and FEP can be selected. The thickness of the release layer 53 is preferably 1 to 100 μm. When the thickness of the release layer 53 is less than 1 μm, there arises a problem that a part having poor release property is formed due to uneven coating of the coating film, or the durability is insufficient. Further, when the release layer exceeds 100 μm, there is a problem that heat conduction is deteriorated. In particular, in the case of a resin release layer, the hardness becomes too high, and the effect of the elastic layer 52 is lost.

  In the present invention, by applying the toner containing the low softening point substance described above, the toner itself has releasability and durability is improved.

(C) Nip The fixing nip portion N composed of a fixing belt and a pressure member in the heat fixing apparatus used in the image forming method of the present invention has a width of 5.0 to 15.0 mm in order to ensure good fixability. A nip is preferably formed. If the width of the fixing nip N is less than 5.0 mm, it is impossible to give a sufficient amount of heat for fixing the toner to the unfixed toner at the time of forming a full-color image, and the toner cannot be melted and mixed, resulting in an unnatural color image. This is not preferable.

  If the width of the fixing nip N exceeds 15.0 mm, a sufficient amount of heat can be applied to fix the toner, but hot offset during fixing is likely to occur. It is not preferable because the change in curvature becomes too large at both ends (upstream end and downstream end of the fixing belt 34), and the durability of the fixing belt 34 is significantly deteriorated.

(D) Surface Pressure The pressure (surface pressure) at the nip portion in the fixing device is preferably in the range of surface pressure 9 × 10 ^{3 to} 5 × 10 ⁵ N / m ^{2 with} the recording material interposed, and surface pressure 3 ×. The range of 10 ^{4 to} 3.5 × 10 ⁵ N / m ² is more preferable. If the surface pressure is less than 9 × 10 ³ N / m ^2, it is not preferable because the recording material is likely to be transported and the fixing is insufficient due to insufficient fixing pressure. Further, when the surface pressure exceeds 5 × 10 ⁵ N / m ² , the durability deterioration of the fixing belt 34 is remarkably deteriorated, which is not preferable.

The surface pressure here is calculated by the following equation from the pressure applied to the transfer material and the contact length L _R (see FIG. 3).

  The pressure applied to the transfer material can be adjusted by the spring pressure of the springs 35a and 35b in FIG. That is, the surface pressure is controlled by arbitrarily changing the spring constant of the springs used for 35a and 35b. It is also possible to control the surface pressure by controlling the distance between the spring stop positions 39a and 39b and the pressure roller 30.

(E) Fixing Belt Perimeter and Fixing Speed In this example, by setting the circumference of the fixing belt 34 provided with the base layer 51 and the time required for the fixing belt 34 to make one rotation as follows. The quick start is achieved and the power consumption is reduced while ensuring stable fixing performance.

  Since the base layer 51 of the fixing belt 34 is thin, the heat capacity is small, and because the metal has a high thermal conductivity, the heat dissipation is good. For this reason, when the peripheral length of the fixing belt 34 exceeds 200 mm, the temperature drop during one rotation of the fixing belt 34 is so large that quick start cannot be performed. In addition, power consumption increases due to an increase in heating area accompanying an increase in circumference. For this reason, the circumference of the fixing belt 34 is desirably 200 mm or less. On the other hand, when the circumferential length of the fixing belt 34 is less than 70 mm, the curvature change becomes too large at both ends of the fixing nip portion N (the upstream end and the downstream end of the fixing belt 34), and the durability of the fixing belt 34 is increased. Is significantly worse. For this reason, the circumference of the fixing belt is desirably 70 mm or more.

  Further, the rotational movement speed (fixing speed) of the fixing belt 34 is preferably 5 to 300 mm / sec for ensuring both practicality and fixability, and more preferably 50 to 280 mm / sec. When the rotational movement speed (fixing speed) of the fixing belt 34 is less than 5 mm / sec, even if on-demand fixing is realized, it takes time to output and is not practical. If it exceeds 300 mm / sec, the fixing belt 34 cannot be stably rotated, and the fixing belt 34 is damaged. For this reason, the process speed as the rotational movement speed V of the fixing belt 34 is desirably 300 mm / sec or less.

(F) Temperature detection means In this example, a thermistor 62a as a temperature detection means is in contact with the non-contact surface side of the ceramic heater 61 in FIG. 6 with the fixing belt, and the thermistor 62a Temperature control is performed by detecting the temperature.

  Further, another thermistor 62b is provided in contact with the inner side of the fixing belt in the rotational direction downstream from the fixing belt nip N. This is because the thermistor 62b exists at a position away from the fixing belt, and therefore the temperature responsiveness is poor. When the thermistor is provided outside the fixing belt, the toner that cannot be fixed completely adheres to it, and the responsiveness is deteriorated, or the belt surface is damaged and image unevenness occurs, which is not preferable. From the viewpoint of temperature responsiveness, the thermistor 62b is preferably provided at a position downstream from the fixing nip center position within the range of 10% to 50% of the total length of the fixing belt in the rotational direction. If the position is less than 10% of the length from the nip, it will interfere with the ceramic heater and guide, making it difficult to design. If it exceeds 50%, the temperature responsiveness is poor and the fluctuation range of the fixing temperature becomes large.

  EXAMPLES Hereinafter, the present invention will be specifically described by way of examples, but this does not limit the present invention in any way.

[Example 1]
910 parts by mass of ion-exchanged water and 450 parts by mass of 0.1 mol / liter-Na ₃ PO ₄ aqueous solution are added to a 2 liter four-necked flask equipped with a high-speed stirring device TK-homomixer, and the rotational speed is 12000 rpm. And heated to 55 ° C. To this, 68 parts by mass of 1.0 mol / liter-CaCl ₂ aqueous solution was gradually added to prepare a dispersion medium system containing a minute hardly water-soluble dispersant Ca ₃ (PO ₄ ) ₂ .

On the other hand, the dispersoid system is
Styrene monomer 160 parts by weight 2-ethylhexyl acrylate monomer 40 parts by weight Pigment Blue 15: 3 20 parts by weight Saturated polyester resin 10 parts by weight (polycondensate of bisphenol A and terephthalic acid, acid value = 12, glass transition point = 60 ° C)
・ Dialkyl salicylic acid metal compound 2 parts by mass (E-84: manufactured by Orient Chemical Co., Ltd.)
-Ethylene glycol diacrylate 0.4 parts by mass-Divinylbenzene 0.05 parts by mass-Low softening point substance 30 parts by mass (polyamide wax, Mw = 900, Mn = 700, Mw / Mn = 1.2)
After the mixture was dispersed for 3 hours using an attritor, a dispersion added with 8 parts by mass of 2,2′-azobis (2,4-dimethylvaleronitrile) as a polymerization initiator was put into the dispersion medium. The granulation was continued for 12 minutes while maintaining the rotational speed. After that, the stirrer was changed from a high-speed stirrer to a propeller stirring blade, the internal temperature was raised to 65 ° C., polymerization was continued at 50 rpm for 3 hours, then the temperature was raised to 85 ° C. over 1 hour, and then polymerization was continued for 6 hours. did.

  After the polymerization, the slurry is rapidly cooled with a jacket temperature of 5 ° C. or less, diluted hydrochloric acid is added to dissolve the dispersant, filtered, washed with water, dried to obtain colored particles, and then a hot air convection type treatment device (flash) Using a jet dryer (manufactured by Seishin Enterprise Co., Ltd.), post-treatment was performed at a product temperature of 55 to 65 ° C. to obtain cyan particles (1). When the circularity distribution and the particle size distribution of the obtained cyan particles (1) were measured using a flow type particle image measuring apparatus, the average circularity was 0.979.

  Mitsui was added with 1.0 part by mass of hydrophobized titania fine powder and 1.0 part by mass of hydrophobized silica fine powder to 100 parts by mass of the obtained cyan particles (1). Cyan toner (1) was obtained by uniform diffusion using a Henschel mixer manufactured by Mining. The physical properties are shown in Table 1.

  The obtained cyan toner (1) was evaluated by the following method.

〔Evaluation methods〕
Using the image forming apparatus shown in FIG. 1, cyan toner (1) was filled in four developing units, and evaluation was performed under the following conditions.

Using cyan toner (1), a belt-like toner unfixed image having a toner carrying amount of 0.5 to 0.6 dg / m ² is formed on the leading edge of the recording paper having a basis weight of 75 or 80 g / m ^2. A fixing test was performed at a process speed of 130 mm / sec using the fixing device shown below. The fixing evaluation results are shown in Table 3.

  The preparation of the unfixed image and the fixability test are performed under normal temperature and normal humidity (23 ° C./60%) unless otherwise specified.

  The fixing device has the configuration shown in FIGS. 3 and 4, and the oil application mechanism is omitted. Aluminum nitride was used for the heating element. The configuration of the fixing belt is the layer structure shown in FIG. 5. The base layer 51 is a 30 μm thick SUS layer, the elastic layer 52 is a 300 μm thick silicone rubber (hardness 40 °: Asker-C 500 g), The release layer 3 was coated with perfluoroalkoxyalkane (PFA) resin to a thickness of 50 μm.

  As the pressure roller 30, a roller having a roller hardness of 60 ° (Asker-C 500 g), in which a core rubber 30 a made of Fe is coated with silicone rubber and PFA resin, was used.

As the pressing force, the pressure springs 35a and 35b were adjusted to contact with a surface pressure of 1 × 10 ⁵ N / m ² through 80 g / cm ² of paper, and the fixing nip was 6.0 mm.

(Fixing start temperature)
The unfixed image created by the above method was fixed by heating the fixing device at a temperature of 100 to 230 ° C. every 5 ° C., and a load of 4900 N / m ² was applied to the obtained fixed image. The temperature at which the image density decrease rate before and after rubbing is 10% or less is defined as the fixing start temperature. The following four ranks were evaluated according to the degree.
A: The fixing start temperature is less than 140 ° C.
B: The fixing start temperature is 140 ° C. or higher and lower than 150 ° C.
C: The fixing start temperature is 150 ° C. or higher and lower than 160 ° C.
D: The fixing start temperature is 160 ° C. or higher.

(High temperature offset resistance)
The fixing temperature is raised, and the highest temperature at which no offset phenomenon occurs visually is defined as a high temperature offset free temperature, which is used as an index of offset resistance. The following four ranks were evaluated according to the degree.
A: The high temperature offset free temperature is 210 ° C. or higher.
B: High temperature offset free temperature is 200 ° C. or higher and lower than 210 ° C.
C: High temperature offset free temperature is 190 ° C or higher and lower than 200 ° C.
D: High temperature offset free temperature is less than 190 ° C.

(Fixing stability)
The unfixed image created by the above method is continuously fed through 10,000 sheets under the condition of the heating unit set temperature of 170 ° C., and the fixability of the first sheet and the 10,000th sheet is confirmed. The obtained fixed image is rubbed twice with sylbon paper applied with a load of 4900 N / m ² , and fixing is performed when the image density reduction rate before and after the rubbing becomes 10% or less. The following four ranks were evaluated according to the degree.
A: Initially fixed after passing 10,000 sheets and the reduction rate is 10% or less.
B: Fixed at the beginning, but not offset after passing 10,000 sheets, but the density reduction rate is 10% or more.
C: Initially fixed, but offset after 10,000 sheets passed, and the back surface is dirty.
D: Offset is in the initial stage.

(Image gloss (gloss) measurement)
The glossiness measuring instrument used in the present invention was “PG-3D” (incident angle θ = 75 °) manufactured by Nippon Denshoku Industries Co., Ltd., and the standard surface was black glass with a glossiness of 96.9. As charts, nine unfixed 30 mm × 30 mm patch unfixed images were output on Xerox 4024 paper (75 g paper) or CLC-SK paper (Canon).

(Image gross difference)
Nine 30mm x 30mm size patch images are output on Xerox 4024 paper (75g paper, legal size) or CLC-SK A3 size paper (Canon), heating unit set temperature 170 ° C, process speed Paper was passed under the condition of 100 mm / sec.

  From the viewpoint of the followability of the fixing temperature, the difference between the average gloss value at the three front edge portions of the image and the average gloss value at the three rear edge portions when one sheet was passed was evaluated.

In addition, from the viewpoint of quick start properties, the difference between the average gloss values of the first sheet and the 50th sheet when the 50 sheets were continuously fed immediately after the start under low temperature and low humidity was evaluated. The following four ranks were evaluated according to the degree.
A: The gross difference is less than 5.
B: The gloss difference is 5 or more and less than 10.
C: The gloss difference is 10 or more and less than 15.
D: The gloss difference is 15 or more.

(transparency)
The transmittance with respect to the amount of each toner per unit area of the fixed image obtained on the OHP sheet is measured, and the transparency is evaluated using a numerical value at a toner loading amount of 0.60 dg / m ² per unit area. The transmittance measurement method is described below.

The transmittance is measured using a Shimadzu spectrophotometer “UV2200” (manufactured by Shimadzu Corporation), and the transmittance of the OHP film alone is 100%.
For magenta toner: 550 nm
For yellow toner: 410 nm
For cyan toner: 650 nm
The transmittance at the maximum absorption wavelength at is measured. The following four ranks were evaluated according to the degree.
A: The transmittance is 70% or more.
B: The transmittance is 60% or more and less than 70%.
C: The transmittance is 50% or more and less than 60%.
D: The transmittance is less than 50%.

  By controlling the toner shape and toner physical properties to the values specified by the present invention, it is possible to ensure good fixability, and the fixing device according to the present invention having an elastic layer having a hardness determined in accordance with this allows quick start performance. Well, psychologically give the user peace of mind, do not feel tired even when viewing many sheets, and make the gloss to be uniform (gross) even at the leading and trailing edges of the image on the heated material, and even on many sheets It was confirmed that

( Reference Example 2)
Other than using polyketone wax (Mw = 2900, Mn = 1200, Mw / Mn = 2.4) instead of polyamide wax (Mw = 900, Mn = 700, Mw / Mn = 1.2) as a low softening point material Were produced in the same manner as in Example 1 and evaluated in the same manner as in Example 1. Table 1 shows the physical properties of the toner, and Table 3 shows the evaluation results.

( Reference Example 3)
The addition amount of the low softening point substance of Example 1 was changed from 30 parts by mass to 12 parts by mass, and the addition amount of the saturated polyester resin was changed from 10 parts by mass to 5 parts by mass. A cyan toner (3) was prepared in the same manner as in Example 1 except that 5 parts by mass of a polycondensate with fumaric acid, acid value 11, glass transition point 60 ° C.) was used, and evaluation was performed in the same manner as in Example 1. did. Table 1 shows the physical properties of the toner, and Table 3 shows the evaluation results.

( Reference Example 4)
The addition amount of the low softening point substance of Example 1 was changed from 30 parts by mass to 40 parts by mass, and the addition amount of ethylene glycol diacrylate was changed from 0.4 parts by mass to 0.1 parts by mass. A cyan toner (4) was produced in the same manner as in Example 1 except that the amount was changed from 8 parts by mass to 12 parts by mass and evaluated in the same manner as in Example 1. Table 1 shows the physical properties of the toner, and Table 3 shows the evaluation results.

( Reference Example 5)
A cyan toner (5) was prepared in the same manner as in Example 1 except that the slurry was not rapidly cooled after the polymerization was completed, and thereafter the post-treatment was not performed using a processing apparatus of the type in which hot air was convected. Evaluation was performed in the same manner as in 1. Table 1 shows the physical properties of the toner, and Table 3 shows the evaluation results.

(Example 6)
A cyan toner (6) was produced in the same manner as in Example 1 except that the processing was carried out at a product temperature of 75 to 85 ° C. using a processing device (flash jet dryer: manufactured by Seishin Enterprise Co., Ltd.) that convected hot air. Evaluation was conducted in the same manner as in Example 1. Table 1 shows the physical properties of the toner, and Table 3 shows the evaluation results.

(Example 7)
1 part by mass of polyamide wax fine particles granulated and classified to 1 μm or less with respect to 100 parts by mass of cyan particles (1) was uniformly processed using a hybridizer manufactured by Nara Machinery Co., Ltd. to obtain cyan particles (2). To 100 parts by mass of the obtained treated cyan particles (2), 1.0 part by mass of the titania fine powder subjected to the hydrophobization treatment and 1.0 part by mass of the silica fine powder subjected to the same hydrophobization treatment were added, Cyan toner (7) was obtained by uniform diffusion using a Henschel mixer manufactured by Mitsui Mining Co., Ltd. Evaluation was performed in the same manner as in Example 1. Table 1 shows the physical properties of the toner, and Table 3 shows the evaluation results.

(Example 8)
1 part by mass of styrene-2-ethylhexyl acrylate copolymer fine particles granulated and classified to 1 μm or less with respect to 100 parts by mass of cyan particles (1) was uniformly treated using a hybridizer manufactured by Nara Machinery Co., Ltd., to obtain cyan particles (3). Obtained. To 100 parts by mass of the obtained treated cyan particles (3), 1.0 part by mass of the titania fine powder subjected to the hydrophobization treatment and 1.0 part by mass of the silica fine powder subjected to the hydrophobization treatment were added, Cyan toner (8) was obtained by uniform diffusion using a Henschel mixer manufactured by Mitsui Mining Co., Ltd. Evaluation was performed in the same manner as in Example 1. Table 1 shows the physical properties of the toner, and Table 3 shows the evaluation results.

Example 9
-Styrene-2-ethylhexyl acrylate-ethylene glycol-diacrylate copolymer (glass transition point 65 ° C) 100 parts by mass-Phthalocyanine pigment 7 parts by mass (CI Pigment Blue 15: 3)
・ Saturated polyester resin 5 parts by mass (polycondensate of bisphenol A and terephthalic acid, acid value 10, glass transition point 65 ° C.)
・ Dialkyl salicylic acid metal compound 1 part by mass (E-84: manufactured by Orient Chemical Co., Ltd.)
-Low softening point material 8 parts by mass (polyamide wax, Mw = 900, Mn = 700, Mw / Mn = 1.2)
The above mixture was premixed with a Henschel mixer, melt-kneaded at a temperature of 130 ° C. with a twin-screw extruder kneader, cooled, coarsely pulverized with a hammer mill, and then pulverized with an air jet fine pulverizer. This was classified and then subjected to a post-treatment at a product temperature of 55 to 65 ° C. using a processing apparatus (flash jet dryer: manufactured by Seishin Enterprise Co., Ltd.) that convects hot air to obtain cyan particles (4).

  To 100 parts by mass of the cyan particles (4), 1.0 part by mass of the titania fine powder subjected to the hydrophobization treatment and 1.0 part by mass of the silica fine powder subjected to the hydrophobization treatment were added. Cyan toner (9) was obtained by uniform diffusion using a Henschel mixer. Evaluation was performed in the same manner as in Example 1. Table 1 shows the physical properties of the toner, and Table 3 shows the evaluation results.

(Example 10)
A magenta toner (1) was produced in the same manner as in Example 1 except that Pigment Red 122 was used as the colorant, and evaluated in the same manner as in Example 1. The physical properties of the toner are the same as those of the cyan toner (1). The evaluation results are shown in Table 3.

(Example 11)
A yellow toner (1) was produced in the same manner as in Example 1 except that Pigment Yellow 93 was used as the colorant, and evaluated in the same manner as in Example 1. The physical properties of the toner are the same as those of the cyan toner (1). The evaluation results are shown in Table 3.

(Example 12)
A black toner (1) was prepared in the same manner as in Example 1 except that carbon black was used as the colorant, and evaluated in the same manner as in Example 1. The physical properties of the toner are the same as those of the cyan toner (1). The evaluation results are shown in Table 3.

(Example 13)
Evaluation was performed in the same manner as in Example 1 using the same toner as in Example 1 except that the thickness of the base layer of the fixing belt was changed to 230 μm. The evaluation results are shown in Table 3.

(Example 14)
Evaluation was performed in the same manner as in Example 1 using the same toner as in Example 1 except that the thickness of the elastic layer of the fixing belt was changed to 530 μm. The evaluation results are shown in Table 3.

(Example 15)
Evaluation was performed in the same manner as in Example 1 using the same toner as in Example 1 except that the thickness of the release layer of the fixing belt was changed to 130 μm. The evaluation results are shown in Table 3.

(Example 16)
Evaluation was conducted in the same manner as in Example 1 except that silicone rubber having a slightly low crosslink density was used as the elastic layer of the fixing belt and the rubber hardness was set to 15 °. The evaluation results are shown in Table 3.

(Example 17)
Evaluation was made in the same manner as in Example 1 using the same toner as in Example 1 except that silicone rubber having a slightly high crosslink density was used as the elastic layer of the fixing belt and the rubber hardness was 45 °. The evaluation results are shown in Table 3.

(Example 18)
Using the image forming apparatus shown in FIG. 2, four four developing devices are filled with yellow toner (1), magenta toner (1), cyan toner (1), and black toner (1), as in Example 1. When the full-color evaluation was performed under the same conditions as in Example 1, the results were satisfactory in terms of low-temperature fixability, gloss uniformity, color mixing, OHT transparency, and the like.

(Comparative Example 1)
The same as Example 1 except that 10 parts by mass of an unsaturated polyester resin (polycondensate of bisphenol A and fumaric acid, acid value 11, glass transition point 60 ° C.) is used instead of the saturated polyester resin of Example 1. A cyan toner (10) was prepared and evaluated in the same manner as in Example 1. The physical properties of the toner are shown in Table 2, and the evaluation results are shown in Table 4.

(Comparative Example 2)
In place of ethylene glycol diacrylate in Example 1, styrene dimer was added as a chain transfer agent, the addition amount of the polymerization initiator was changed from 8 parts by mass to 12 parts by mass, and the internal temperature after high-speed stirring was changed to 80 ° C. It is that other than is to prepare a cyan toner (11) in the same manner as in example 1, was evaluated in the same manner as in example 1. The physical properties of the toner are shown in Table 2, and the evaluation results are shown in Table 4.

(Comparative Example 3)
The addition amount of the low softening point substance of Example 1 was changed from 30 parts by mass to 4 parts by mass, and the addition amount of the saturated polyester resin was changed from 10 parts by mass to 7 parts by mass. A cyan toner (12) was prepared in the same manner as in Example 1 except that 3 parts by mass of a polycondensate with fumaric acid, acid value 11, glass transition point 60 ° C.) was used, and evaluation was performed in the same manner as in Example 1. did. The physical properties of the toner are shown in Table 2, and the evaluation results are shown in Table 4.

(Comparative Example 4)
The addition amount of the low softening point substance of Example 1 was changed from 30 parts by mass to 60 parts by mass, and the addition amount of ethylene glycol diacrylate was changed from 0.4 parts by mass to 0.1 parts by mass. A cyan toner (13) was produced in the same manner as in Example 1 except that the amount was changed from 8 parts by mass to 12 parts by mass and evaluated in the same manner as in Example 1. The physical properties of the toner are shown in Table 2, and the evaluation results are shown in Table 4.

(Comparative Example 5)
A cyan toner (14) was produced in the same manner as in Example 1 except that the amount of divinylbenzene added was 0.4 parts by mass without adding the ethylene glycol diacrylate of Example 1, and Evaluation was performed in the same manner. The physical properties of the toner are shown in Table 2, and the evaluation results are shown in Table 4.

(Comparative Example 6)
A cyan toner (15) was prepared in the same manner as in Example 1 except that the ethylene glycol diacrylate of Example 1 was not added and the internal temperature after high-speed stirring was 80 ° C. Evaluated. The physical properties of the toner are shown in Table 2, and the evaluation results are shown in Table 4.

(Comparative Example 7)
Except for changing the addition amount of the low softening point substance of Example 1 from 30 parts by mass to 1 part by mass and further changing the addition amount of ethylene glycol diacrylate from 0.4 parts by mass to 0.2 parts by mass. A cyan toner (16) was produced in the same manner as in Example 1 and evaluated in the same manner as in Example 1. The physical properties of the toner are shown in Table 2, and the evaluation results are shown in Table 4.

(Comparative Example 8)
The addition amount of the low softening point substance of Example 1 was changed from 30 parts by mass to 110 parts by mass, and the addition amount of the saturated polyester resin was changed from 10 parts by mass to 9 parts by mass. A cyan toner (17) was prepared in the same manner as in Example 1 except that 1 part by mass of a polycondensate with fumaric acid, acid value of 11, and glass transition point of 60 ° C. was used, and evaluated in the same manner as in Example 1. did. The physical properties of the toner are shown in Table 2, and the evaluation results are shown in Table 4.

(Comparative Example 9)
Evaluation was made in the same manner as in Example 1 using the same toner as in Example 1 except that the fixing belt without an elastic layer was used. The evaluation results are shown in Table 4.

(Comparative Example 10)
Evaluation was made in the same manner as in Example 1 except that silicone rubber having a low crosslinking density was used as the elastic layer of the fixing belt and the rubber hardness was set to 5 °. The evaluation results are shown in Table 4.

(Comparative Example 11)
Evaluation was conducted in the same manner as in Example 1 except that silicone rubber having a high crosslinking density was used as the elastic layer of the fixing belt and the rubber hardness was 55 °. The evaluation results are shown in Table 4.

It is a schematic explanatory drawing which shows an example of the image forming apparatus which enforces the image forming method of this invention. It is a schematic explanatory drawing which shows the other example of the image forming apparatus which implements the image forming method in this invention. 1 is a schematic front view of a heat fixing device used in the present invention. FIG. 4 is a schematic longitudinal sectional view of the heat fixing device of FIG. 3. 2 is a schematic cross-sectional view of a fixing belt used in the present invention. FIG. It is a cross-sectional schematic diagram of the heat fixing apparatus of FIG.

1,11 Photosensitive drum (image carrier)
2,12 Charging device 3,13 Laser beam 4,14 Developing device 5,21 Heat fixing device 6,16 Transfer roller 7,18 Cleaner 8,20 Laser optical box (laser scanner)
14Y, 14M, 14C, 14B Developer 15 Intermediate transfer drum 19 Mirror 30 Pressure roller 30a Core 30b Elastic material layer 31a, 31b Belt guide member 31e Convex rib portion 32 Pressing rigid stay 34 Fixing belt 35a, 35b Pressing Spring 39a, 39b Spring receiving member 40 Good heat conducting member 51 Base layer 52 Elastic layer 53 Release layer 60 Ceramic heater 62a, 62b Temperature sensor (thermistor)

Claims (20)

At least a heating body fixed at a predetermined position, a fixing belt having an elastic layer having a rubber hardness of 10 to 50 ° according to JIS-A, which is pressed against the heating body, and a temperature detection unit, the detection means is brought into contact with the fixing belt inner surface a recording material through the fixing belt while the temperature adjusted into close contact with the heating body is heated and fixed toner image on the recording material to the recording material, the temperature The detection means is provided in contact with the position downstream of the fixing belt in the rotational direction from the center of the nip where the fixing belt is in contact with the recording material, and more than 10% of the total fixing belt length in the rotational direction from the fixing nip center position is 50% or more. A toner applied to an image forming apparatus provided with a heat fixing device provided at a position downstream of the length , wherein the toner includes the following (a) to ( h ):
(A) The toner contains 0.5 to 30% by mass of a low softening point substance.
(B) The weight average molecular weight (Mw) in the molecular weight distribution measured by gel permeation chromatography (GPC) of the tetrahydrofuran (THF) soluble content of the toner is 10,000 to 1,000,000, and the weight average The ratio (Mw / Mn) of molecular weight (Mw) to number average molecular weight (Mn) is 3 to 20,
(C) The insoluble content of the toner by Soxhlet extraction with a tetrahydrofuran solvent is 3 to 30% by mass.
(D) storage elastic modulus at a temperature of 50 ° C. of the toner (G _'50) and a storage modulus at a temperature 100 ° C. of the toner (G' ratio of _{100) (G '50 / G} ' 100) is 5,000～70 , 000,
(E) The storage elastic modulus (G ′ ₁₅₀ ) of the toner at a temperature of 150 ° C. is 1 × 10 ³ to 1 × 10 ⁵ (dN / m ² ).
(F) The toner melt index (temperature 135 ° C., load 2.2 kg) in 10 minutes is 1 to 40 g.
(G) The methanol wettability half-value of the toner base particles is 13 to 63%.
(H) In the molecular weight distribution measured by GPC, the low softening point substance has a weight average molecular weight (Mw) to number average molecular weight (Mn) ratio (Mw / Mn) of 1.0 to 1.5.
A toner characterized by satisfying The toner according to claim 1, wherein a contact angle with water after heating the mother particles of the toner at 100 ° C. for 2 minutes is 102 to 130 °. 3. The toner according to claim 1, wherein an average circularity satisfies 0.950 to 1.0 in a particle size distribution according to a circle-equivalent diameter of toner particles measured by a flow type particle image analyzer of the toner. The toner is produced by a polymerization method in which a polymerizable monomer composition containing at least a polymerizable monomer, a low softening point substance, and a colorant is polymerized in a solvent liquid in the presence of a polymerization initiator. The toner according to any one of 1 to 3. The toner according to claim 1, wherein the fixing belt is not provided with an oil application mechanism. The fixing belt has at least a base layer, an elastic layer, and a release layer. The base layer has a thickness of 1 to 200 μm, the elastic layer has a thickness of 100 to 500 μm, and the release layer has a thickness of 1 to 100 μm. The toner according to claim 1. The toner according to claim 1, wherein the elastic layer of the fixing belt contains zinc oxide as a heat conductive material. Surface pressure of the fixing belt against the recording material is 9 × 10 ^Three ~ 5x10 ^Five N / m ² The toner according to claim 1, wherein the toner image is heat-pressed and fixed at a fixing speed of 5 to 300 mm / second while being pressed. The toner according to claim 1, wherein the heating body is a ceramic heater. The toner according to claim 9, wherein the ceramic heater is made of aluminum nitride. At least a heating body fixed at a predetermined position, a fixing belt having an elastic layer having a rubber hardness of 10 to 50 ° according to JIS-A, which is pressed against the heating body, and a temperature detection unit, While adjusting the temperature by bringing the detecting means into contact with the inner surface of the fixing belt, the recording material is brought into close contact with the heating body via the fixing belt, and the toner image on the recording material is heated and fixed on the recording material. The detection means is provided in contact with the position downstream of the fixing belt in the rotational direction from the center of the nip where the fixing belt is in contact with the recording material, and more than 10% of the total fixing belt length in the rotational direction from the fixing nip center position is 50% or more. An image forming method having a step provided at a position downstream of the length,
The toners constituting the toner image are the following (a) to (h).
(A) The toner contains 0.5 to 30% by mass of a low softening point substance.
(B) The weight average molecular weight (Mw) in the molecular weight distribution measured by gel permeation chromatography (GPC) of the tetrahydrofuran (THF) soluble content of the toner is 10,000 to 1,000,000, and the weight average The ratio (Mw / Mn) of molecular weight (Mw) to number average molecular weight (Mn) is 3 to 20,
(C) The insoluble content of the toner by Soxhlet extraction with a tetrahydrofuran solvent is 3 to 30% by mass.
(D) Storage elastic modulus (G ′) of toner at 50 ° C. ₅₀ ) And the storage elastic modulus (G ′) of the toner at 100 ° C. ₁₀₀ ) (G ’) ₅₀ / G ’ ₁₀₀ ) Is 5,000 to 70,000,
(E) Storage elastic modulus (G ′) of toner at 150 ° C. ₁₅₀ ) Is 1 × 10 ^Three ~ 1x10 ^Five (DN / m ² )
(F) The toner melt index (temperature 135 ° C., load 2.2 kg) in 10 minutes is 1 to 40 g.
(G) The methanol wettability half-value of the toner base particles is 13 to 63%.
(H) In the molecular weight distribution measured by GPC, the low softening point substance has a weight average molecular weight (Mw) to number average molecular weight (Mn) ratio (Mw / Mn) of 1.0 to 1.5.
An image forming method characterized by satisfying the above. The image forming method according to claim 11, wherein the toner base particles have a contact angle with water of 102 to 130 ° after being heated at 100 ° C. for 2 minutes. 13. The image forming method according to claim 11, wherein an average circularity satisfies 0.950 to 1.0 in a particle size distribution according to an equivalent circle diameter of toner particles measured by the flow type particle image analyzer of the toner. The toner is produced by a polymerization method in which a polymerizable monomer composition containing at least a polymerizable monomer, a low softening point substance, and a colorant is polymerized in a solvent liquid in the presence of a polymerization initiator. The image forming method according to any one of 11 to 13. The image forming method according to claim 11, wherein the fixing belt is not provided with an oil application mechanism. The fixing belt has at least a base layer, an elastic layer, and a release layer. The base layer has a thickness of 1 to 200 μm, the elastic layer has a thickness of 100 to 500 μm, and the release layer has a thickness of 1 to 100 μm. The image forming method according to claim 11. The image forming method according to claim 11, wherein the elastic layer of the fixing belt contains zinc oxide as a heat conductive material. Surface pressure of the fixing belt against the recording material is 9 × 10 ^Three ~ 5x10 ^Five N / m ² The image forming method according to claim 11, wherein the toner image is heated and pressure-fixed at a fixing speed of 5 to 300 mm / second while being pressed. The image forming method according to claim 11, wherein the heating body is a ceramic heater. The image forming method according to claim 19, wherein the ceramic heater is made of aluminum nitride.

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