JP4313829B2 - Full-color image forming apparatus and full-color image forming method - Google Patents

Description

  The present invention relates to a full-color image forming apparatus and a full-color image forming method using a full-color toner such as electrophotography, and more particularly, to forming a full-color image using a full-color toner using a styrene-acrylic resin as a binder resin. The present invention relates to an apparatus and a full-color image forming method.

  In recent years, electrophotographic image forming apparatuses such as copying machines and printers use color toners of three primary colors of yellow, magenta, and cyan, in addition to conventional monochrome images using only black toner, and furthermore these color toners. In addition, there are many full-color copiers, full-color printers, etc. that can reproduce various colors by appropriately superimposing black toner. Many of the full-color images created by the above apparatus are bright and glossy.

  On the other hand, since the heat efficiency is high, the operating temperature is relatively low at 160 to 200 ° C., the safety is excellent, and the apparatus can be miniaturized. Has been widely used in the past. In this roller fixing method, generally, transfer paper is passed between upper and lower fixing rollers with built-in heaters, and the toner is melted and fixed on the transfer paper while the transfer paper passes through the upper and lower fixing rollers. The glossiness varies depending on the fixing temperature described above.

  Recently, in business use, there is a demand for a medium gloss image having an appropriate gloss, not a high gloss as a full color image. The characteristic of the medium gloss image is that the characters are easy to see and the feeling of the image and the glare are suppressed. In addition, a toner that can be fixed at a lower fixing temperature has been desired due to a demand for energy reduction or the like.

  So far, full-color toners using a polyester resin as a binder resin have been developed to obtain the above-described medium gloss image. On the other hand, it is also conceivable to produce a full-color toner using a styrene-acrylic resin as a binder resin from the viewpoint of environmental stability and cost (for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 11-24307.

  However, when a full-color toner is produced using a conventionally used styrene-acrylic resin, only a low gloss can be obtained, and a desired medium gloss image cannot be obtained. Further, a so-called offset occurs in which toner adheres to the fixing roller.

  In addition, from the point of downsizing and weight reduction of the device and poor writing property to the copy image by oil application, the amount of oil applied to the heating roller of the fixing device is reduced, or no oil is applied to the heating roller. In recent years, the use of so-called oilless fixing devices has been desired. When such an oilless fixing device is used, an offset is more likely to occur compared to a fixing device to which oil is applied. Further, since the separation (release) performance of the toner and the fixing roller is deteriorated, there is a problem that paper is wound around the fixing roller.

  The present invention has been made in view of such conventional problems. The object of the present invention is to use a styrene-acrylic resin as a binder resin and obtain an appropriate gloss without applying oil to the fixing device. Another object of the present invention is to provide a full-color image forming apparatus and a full-color image forming method using a full-color toner that does not cause offset or paper wrapping.

According to the present invention, there is provided a full-color toner characterized by satisfying the following structural requirements (a) to (h) in a full-color toner having at least a binder resin and a colorant.
(A) The full-color toner uses a styrene-acrylic resin as a binder resin, and as an acrylic monomer component in the styrene-acrylic resin, methyl acrylate, ethyl acrylate, propyl acrylate, and It contains at least one acrylate ester consisting of butyl acrylate.
(B) The toner has at least one peak in the (weight average) molecular weight distribution measured by GPC.
(C) The molecular weight distribution has a main peak in a region having a molecular weight of 6 × 10 ^{3 to} 6 × 10 ⁴ .
(D) In the molecular weight distribution, the ratio of the component having a molecular weight of 1 × 10 ³ or less to the whole toner is 10% by weight or less.
(E) In the molecular weight distribution, the ratio of components having a molecular weight of 2 × 10 ⁵ or more to the whole toner is 7% by weight or less.
(F) In the molecular weight distribution, when the weight average molecular weight is Mw and the number average molecular weight is Mn, the value of Mw / Mn is 2 ≦ Mw / Mn ≦ 15.
(G) The toner softening point is Tm (° C.), and the DSC curve measured by the differential scanning calorimeter of the toner is the endothermic peak temperature at the time of temperature rise corresponding to the release agent is Wp (° C.). Sometimes 10 ≦ Tm−Wp ≦ 60.
(H) When a solid image is formed, the glossiness (according to JIS-Z8741 60-degree specular gloss measurement method / incident angle: 60 degrees) in the solid image is a value within the range of 7-20.
That is, when such a predetermined full color toner is used, a fixing device having a fixing temperature in a range of 140 to 200 ° C., and a solid image is formed, the glossiness (JIS- Z8741 60 degree specular gloss measurement method / incident angle: 60 degrees) is set to a value within the range of 7 to 20, and a full color image forming method using the same is provided. .

  With full-color toners using styrene-acrylic resins that have been studied so far, only low gloss images can be obtained. On the other hand, it is considered that the molecular weight of the toner is greatly involved in obtaining a medium gloss image desired for business use. It is thought that if the molecular weight of the toner is lowered, the viscosity of the toner can be lowered and a medium gloss image can be obtained. However, even if the molecular weight is lowered, a medium gloss image cannot be obtained and the offset is reduced. It sometimes occurred. Further, even if the characteristics of a full-color toner using a polyester resin as a binder resin that has been able to obtain a medium gloss image have been applied to a styrene-acrylic resin as it is, the same performance could not be obtained. Moreover, when oil is not applied to the fixing device, it has not been possible to prevent offset and paper wrapping around the fixing roller.

  Therefore, as a result of intensive studies on whether or not a medium gloss image can be obtained depending on the distribution degree and peak position in the molecular weight distribution of the toner, the present inventors have found that the peak with the largest area exists in a specific range. Whether the molecular weight distribution is broad (a wide range of molecular weights where toner particles are present) or sharp (a relatively narrow molecular weight range where toner particles are present) It has been found that, by using the toner, it is possible to obtain a toner that does not cause offset or paper wrapping even when a medium gloss image is obtained and no oil is applied to the fixing device. In addition, the temperature range in which a fixable and good image can be obtained can be made wider than before. Moreover, it became possible to respond to various machine specifications.

  The toner of the present invention can be produced by a per se known method such as a pulverization classification method, a melt granulation method, a spray granulation method, a suspension / emulsion polymerization method or the like. The method can be suitably used. In the pulverization classification method, a toner composition such as a binder resin and a colorant and, if necessary, a magnetic powder, a charge control agent, and a release agent are premixed with a Henschel mixer or a V-type mixer, and then a twin screw extruder or the like. Melt kneading using a melt kneading apparatus. The melt-kneaded product is cooled, then coarsely pulverized and finely pulverized, and then classified as necessary to obtain toner particles having a predetermined particle size distribution. If necessary, the surface of the toner particles is treated with a surface treatment agent to obtain a toner. In order to obtain a high-quality image, it is preferable that the toner has a volume center particle size in the range of 5.0 to 12.0 μm.

In the binder resin of the present invention, a styrene-acrylic resin is used. Examples of the styrene monomer component that becomes the base of the styrene-acrylic resin include styrene derivatives such as styrene , α-methylstyrene, p-methylstyrene, pt-butylstyrene, p-chlorostyrene, and hydroxystyrene. be able to.
Examples of the acrylic monomer component include at least one acrylic ester composed of methyl acrylate, ethyl acrylate, propyl acrylate, and butyl acrylate.

  The mixture of the above various monomers can be polymerized by any method such as solution polymerization, bulk polymerization, emulsion polymerization, suspension polymerization, etc., to obtain a binder resin used in the present invention. In the polymerization, usable polymerization initiators include acetyl peroxide, decanoyl peroxide, lauroyl peroxide, benzoyl peroxide, azobisisobutyronitrile, 2,2′-azobis-2,4-dimethylvaleronitrile, 2 , 2′-azobis-4-methoxy-2,4-dimethylvaleronitrile and other known polymerization initiators can be used. These polymerization initiators are preferably used in the range of 0.1 to 15% by weight based on the total weight of the monomers.

  In the present invention, the molecular weight distribution of the toner is measured using GPC (gel permeation chromatography) as follows. The GPC apparatus used for the measurement is HLC-8220 GPC manufactured by Tosoh Corporation, and the column uses TFKgel GMHxl (two series) manufactured by Tosoh Corporation. 100 mg of toner and 20 ml of THF (tetrahydrofuran) are mixed and stirred with a ball mill or the like until they are uniformly dissolved. Thereafter, the supernatant liquid separated by the centrifuge is used as a GPC sample. The toner concentration in the sample is preferably 1 to 10 mg / ml.

  In the measurement, the column of the GPC apparatus was stabilized at 40 ° C. using THF as a solvent, and then flowed through the column at a flow rate of 1 ml per minute at this temperature, and about 100 μl (concentration 2 mg / ml) of the THF sample solution was injected. taking measurement. The molecular weight distribution of the sample is calculated from the relationship between the logarithmic value of the calibration curve prepared using several types of monodisperse polystyrene standard samples and the number of counts. As a standard polystyrene sample for preparing a calibration curve, for example, polystyrene having a molecular weight of 500 to 1,000,000 can be used. As the column, a styrene-divinylbenzene polymer column or the like can also be used.

  The peak in the present invention is a maximum value or a shoulder. Here, the peak of the main component in the present invention will be described with reference to FIG. FIG. 1 is an example of a molecular weight distribution diagram measured by GPC. A straight line is drawn downward from the minimum value of the curve and the shoulder in this molecular weight distribution diagram. A portion between such straight lines is defined as a peak area or a shoulder area. In FIG. 1, the numbers 1 to 6 are the respective peak areas or shoulder areas. In the present invention, the peak having the largest area is defined as the main component peak. That is, in FIG. 1, the peak X at 4 is the main component peak. This example is an illustration for explaining the peak, and the molecular weight of the peak 4 is about 4000, and does not fall within the scope of the claims of the present invention.

  If the peak of the main component is too much in the polymer region, when the fixing temperature is low, the toner becomes difficult to melt, the adhesion between the melted toner and the unmelted toner becomes weak, and so-called cold offset occurs. Further, since the elasticity is strong, the surface of the fixed image becomes rough, and the glossiness of the image becomes low. On the other hand, if the peak of the main component exists in a very low molecular region, when the fixing temperature is high, the elasticity of the toner is weakened, the adhesion between the toners is weakened, and so-called hot offset occurs. Further, when the elasticity of the toner is weakened, the toner is more easily crushed by the fixing roller during fixing, the surface of the fixed image becomes smooth, and the glossiness of the image becomes too high.

Even if the molecular region where the peak of the main component exists is in an appropriate range, it is not possible to widen the range in which the offset does not occur even when the fixing temperature is high or low while obtaining a medium gloss image. Even if the peak of the main component exists in the appropriate molecular region, if too many toner particles are present in the low molecular region or high molecular region, it will be difficult to melt at both low and high fixing temperatures and offset. Is likely to occur, and the temperature range that can be fixed becomes narrow. As a result of repeated experiments, the inventors who have obtained the above viewpoint have at least one peak, and the toner has a main component peak in a molecular weight region of 6 × 10 ^{3 to} 6 × 10 ⁴ , and The ratio of the component having a molecular weight of 1 × 10 ³ or less to the whole toner is 10% by weight or less, the ratio of the component having a molecular weight of 2 × 10 ⁵ or more to the whole toner is 7% by weight or less, and the weight average molecular weight is When Mw and the number average molecular weight are Mn, the value of Mw / Mn is 2 ≦ Mw / Mn ≦ 15, and when a release agent as described later is used, a desired fixing is possible while obtaining a medium gloss image. A temperature range could be obtained.

When the peak of the main component of the toner is in a region lower than the region having a molecular weight of 6 × 10 ^{3 to} 6 × 10 ⁴ , the glossiness becomes too high or hot offset occurs. If the peak of the main component of the toner is in a region higher than the region having a molecular weight of 6 × 10 ^{3 to} 6 × 10 ⁴ , the glossiness becomes too low or a cold offset occurs. When the proportion of the component having a molecular weight of 1 × 10 ³ or less in the whole toner exceeds 10% by weight, hot offset occurs, and the proportion of the component having a molecular weight of 2 × 10 ⁵ or more in the whole toner exceeds 7% by weight. A cold offset occurs. On the other hand, when the value of Mw / Mn is smaller than 2, hot offset occurs. If the value of Mw / Mn is greater than 15, a cold offset occurs.

  The molecular weight distribution of the toner in the present invention is adjusted by the molecular weight of the monomer based on the molecular weight distribution of the styrene-acrylic resin as the binder resin, or at the melt kneading stage of the toner production stage. It can be obtained by adjusting the kneading conditions.

  The binder resin used preferably has a glass transition temperature in the range of 55 to 65 ° C. This is because if the glass transition temperature is less than 55 ° C., the toner may be hardened in the developing device or the toner cartridge, and if it exceeds 65 ° C., the toner may not be sufficiently fixed on the transfer object such as paper.

  In the present invention, the following release agents are used. Conventionally known waxes, for example, aliphatic hydrocarbon waxes such as paraffin wax, petroleum wax, polyethylene wax, polypropylene wax, and oxidized polyethylene wax, montan wax, carnauba wax, beeswax, and wood wax are used. These release agents have a DSC curve measured by a differential scanning calorimeter of the toner, where the softening point of the toner is Tm (° C.), and the peak temperature of the endothermic peak at the time of temperature rise corresponding to the release agent is Wp ( C)), it is necessary to contain so as to satisfy 10 ≦ Tm−Wp ≦ 60. In the case of a fixing device that reduces the amount of oil or does not apply oil at all, the release agent in the toner oozes out between the fixing roller and the toner layer, thereby improving the releasability.

  When Tm-Wp is less than 10 ° C., the toner melts and adheres to the fixing roller before the release agent melts, and good release properties cannot be obtained. Furthermore, the surface of the image is disturbed and gloss is lost, or an offset occurs. Of course, the same problem occurs more remarkably when the peak temperature of the release agent is higher than the melting point of the toner. When Tm-Wp is higher than 60 ° C., the release agent dissolves too early, and the releasability at the temperature at which the toner melts is lowered. As a result, hot offset is likely to occur. These release agents preferably have a melting point of 50 to 140 ° C., particularly 70 to 120 ° C. The content of these release agents is usually 1 to 20 parts by weight, particularly 3 to 10 parts by weight per 100 parts by weight of the binder resin component.

  In DSC measurement in the present invention, DSC2920MDSC manufactured by TA Instruments is used. The measurement method is performed according to ASTM D3418-82. The DSC curve used in the present invention is the DSC curve measured at the time of the second temperature increase after the temperature is increased once and the previous history is taken and then the temperature is decreased at a temperature rate of 10 ° C./min.

  As described above, in the present invention, by using a specific styrene-acrylic resin and a specific release agent, offset and paper wrapping can be effectively prevented while obtaining a medium gloss image.

Examples of the colorant to be contained in the binder resin include the following.
Colorant for black toner: carbon black, acetylene black, lamp black, aniline black, etc.
Colorant for yellow toner: C.I. I. Pigment yellow 1, C.I. I. Pigment yellow 5, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 180, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 4, C.I. I. Pigment yellow 81, C.I. I. Pigment yellow 97, C.I. I. Azo pigments such as CI Pigment Yellow 93; inorganic pigments such as yellow iron oxide and ocher; I. Nitro dyes such as Acid Yellow 1; C.I. I. Solvent Yellow 2, C.I. I. Solvent Yellow 6, C.I. I. Solvent Yellow 14, C.I. I. Solvent Yellow 15, C.I. I. Solvent Yellow 19, C.I. I. Oil-soluble dyes such as Solvent Yellow 21
Colorant for magenta toner: C.I. I. Pigment red 49, C.I. I. Pigment red 57, C.I. I. Pigment red 81, C.I. I. Pigment red 122, C.I. I. Pigment red 184, C.I. I. Pigment red 238, C.I. I. Solvent Red 19, C.I. I. Solvent Red 49, C.I. I. Solvent Red 52, C.I. I. Basic Red 10, C.I. I. Disperse Red 15 etc.
C. Colorant for cyan toner: C.I. I. Pigment blue 15, C.I. I. Pigment blue 16, C.I. I. Solvent Blue 55, C.I. I. Solvent Blue 70, C.I. I. Direct Blue 25, C.I. I. Direct Blue 86 etc.
The above-mentioned colorant is used in an amount of 2 to 20 parts by weight, particularly 4 to 15 parts by weight, per 100 parts by weight of the fixing resin.

  Moreover, a charge control agent can be contained as needed. As the charge control agent, conventionally known charge control agents can be used. For example, as the positively chargeable charge control agent, nigrosine dye, fatty acid-modified nigrosine dye, carboxyl group-containing fatty acid-modified nigrosine dye, quaternary ammonium salt, amine series A compound, an organometallic compound, or the like can be used. As the negatively chargeable charge control agent, a metal complex of oxycarboxylic acid, a metal complex of azo compound, a metal complex dye, a salicylic acid derivative, or the like can be used.

  Moreover, a mold release agent can be contained as needed. Examples of the release agent include conventionally known waxes, for example, aliphatic hydrocarbon waxes such as paraffin wax, petroleum wax, polyethylene wax, polypropylene wax, polyethylene oxide wax, montan wax, carnauba wax, beeswax, and wood wax. Used. These release agents preferably have a melting point of 50 to 140 ° C., particularly 70 to 120 ° C. The content of these release agents is usually 1 to 20 parts by weight, particularly 3 to 10 parts by weight per 100 parts by weight of the binder resin component.

  Moreover, a surface treating agent can be used as needed. Surface treatment agents include inorganic fine powders such as silica, alumina, titanium oxide, zinc oxide, magnesium oxide, and calcium carbonate; organic fine powders such as polymethyl methacrylate to adjust the charge controllability and fluidity of the toner. A fatty acid metal salt such as zinc stearate can be used, and one or more of these can be used in combination. The addition amount of the surface treatment agent is preferably in the range of 0.1 to 2.0 wt% per toner particle. The surface treatment agent and toner particles can be mixed using, for example, a Henschel mixer, a V-type mixer, a turbula mixer, a hybridizer, or the like.

  The toner of the present invention can be used as a one-component developer or a two-component developer. There are no limitations on the carrier used when used as a two-component developer, for example, magnetic metals such as iron, nickel, cobalt and their alloys, or alloys containing rare earths, hematite, magnetite, manganese-zinc Sintering and atomizing magnetic materials such as ferrite, nickel-zinc ferrite, manganese-magnesium ferrite, lithium ferrite and other soft ferrites, copper-zinc ferrite and other iron-based oxides, and mixtures thereof The magnetic particles produced by this method, and those obtained by coating the surfaces of the magnetic particles with a resin can be used.

  The particle diameter of the carrier is generally 30 to 200 μm, particularly preferably 40 to 150 μm, expressed in terms of particle diameter by electron microscopy. Further, the apparent density of the carrier is preferably in the range of 2.4 to 3.0 g / cm 3, although it varies depending on the composition of the magnetic material, the surface structure, etc. when the magnetic material is mainly used.

  As the medium gloss image in the present invention, when a gloss meter (PG-1M manufactured by Nippon Denshoku) is used and the value measured at a viewing angle of 60 degrees is defined as the glossiness, 7 to 20 is desired.

1. Binder resin production example 1
A monomer solution consisting of 70 parts by weight of styrene and 30 parts by weight of butyl acrylate was added to a polymerization initiator V-65 (2,2′-azobis- (2,4-dimethylvaleronitrile), manufactured by Wako Pure Chemical Industries, Ltd.) 6 After dropping for 3 hours in a solution containing 200 parts by weight of toluene and 200 parts by weight of solvent as a solvent (condenser provided, refluxing toluene), and maintaining at 60 ° C. for 12 hours after the addition, Toluene was removed by distillation under reduced pressure, and the binder resin No. 1 for Toner of Example 1 shown in Table 1 was removed. 1 was obtained.

2. Production example 2 of binder resin
The polymerization initiator was 8 parts by weight of V59 (2,2′-azobis- (2-dimethylvaleronitrile), manufactured by Wako Pure Chemical Industries), the polymerization initiation temperature was 40 ° C., and the temperature was increased by 4 ° C. per hour for 12 hours. Except for carrying out the polymerization reaction, the binder resin No. 1 for toner of Example 2 described in Table 1 was prepared in the same manner as in Production Example 1. 2 was obtained.

3. Production Example 3 of Binder Resin
As described in Table 1, except that the polymerization initiator was 7 parts by weight of V65 (2,2′-azobis- (4-methoxy-2,4-dimethylvaleronitrile), manufactured by Wako Pure Chemical Industries, Ltd.) The binder resin No. 1 for the toner of Example 3 was used. 3 was obtained.

4). Production Example 4 of Binder Resin
The polymerization initiator was the same as in Production Example 1, except that 2 parts by weight of V65 and 2 parts by weight of V70 (2,2′-azobis- (2-dimethylvaleronitrile), manufactured by Wako Pure Chemical Industries) were mixed. The binder resin No. 1 for the toner of Example 4 described in Table 1 was used. 4 was obtained.

5. Production Example 5 of Binder Resin
Except that the polymerization initiator was changed to 10 parts by weight of V59, the binder resin No. 5 was obtained.

6). Production Example 6 of Binder Resin
In the same manner as in Production Example 1 except that the polymerization initiator was a mixture of 1 part by weight of V65 and 1 part by weight of V70, the binder resin No. 6 obtained.

7). Production Example 7 of Binder Resin
Comparative Example described in Table 1 in the same manner as in Production Example 1 except that the polymerization initiator was 8 parts by weight of V65, the polymerization initiation temperature was 40 ° C., and the polymerization reaction was performed for 12 hours while raising the temperature by 4 ° C. per hour. No. 1 binder resin No. 1 7 was obtained.

8). Production Example 8 of Binder Resin
In the same manner as in Production Example 1, except that the polymerization initiator was a mixture in which 2 parts by weight of V59 and 2 parts by weight of V70 were mixed, the binder resin No. 8 was obtained.

9. Production Example 9 of Binder Resin
Comparative Example 3 described in Table 1 was used in the same manner as in Production Example 1 except that the polymerization initiator was a mixture in which 3 parts by weight of V-59, 3 parts by weight of V-65, and 3 parts by weight of V-70 were mixed. Binder resin No. for toner Nine obtained.

10. Binder Resin Production Example 10
A binder resin No. 1 for the toner of Comparative Example 4 shown in Table 1 was prepared in the same manner as in Production Example 1 except that 3 parts by weight of V-70 was used as the polymerization initiator. 10 obtained.

11. Production Example 11 of Binder Resin
The binder resin No. 1 for the toner of Comparative Example 5 shown in Table 1 was prepared in the same manner as in Production Example 1 except that the polymerization initiator was changed to 9 parts by weight of V-65. 11 was obtained.

12 Binder resin production example 12
The polymerization initiator was a mixture of 3 parts by weight of V-65 and 1 part by weight of V-70, and the toner of Comparative Example 6 described in Table 1 was prepared in the same manner as in Production Example 1 except that the polymerization time was 14 hours. -Binder resin No. 12 obtained.

13. Binder resin production example 13
In the same production method as in Production Example 2 of the binder resin, the binder resin No. 1 for toners of Comparative Examples 7 and 8 shown in Table 1 were used. 13 were obtained.

[Example 1]
Binder resin no. 1, 3 parts by weight of a quaternary ammonium salt compound (P-51, manufactured by Orient Chemical) as a charge control material, 4 parts by weight of a cyan pigment (PB15-3, manufactured by Cibagayki) as a colorant, and polyethylene as a release agent A resin composition for toner was prepared by mixing 5 parts by weight of wax (155 microwax, manufactured by Japan Petroleum) with a Henschel mixer and then melt-kneading with a twin screw extruder. The obtained resin composition for toner was finely pulverized with an airflow pulverizer and classified with an air classifier to obtain toner particles having an average particle diameter of 8 μm on a volume basis. 0.5 parts by weight of hydrophobic silica (TG820, manufactured by Cabot) as a surface treatment agent and 0.8% by weight of titanium oxide (EC-100T, manufactured by Titanium Industry) with respect to 100 parts by weight of the toner particles. The toner was added and mixed with high stirring with a Henschel mixer to obtain a toner. This toner is blended with a ferrite carrier (EF-60B, manufactured by Powder Tech Co., Ltd.) having an average particle diameter of 80 μm whose surface is coated with a silicone resin so that the toner concentration becomes 5% by weight. A system developer was obtained. The molecular weight distribution of the obtained toner is shown in Table 1 described later.

  For the developer of Example 1 above, using a color printer LS-8000C (manufactured by Kyocera Corporation) with a modified machine (using the toner of the present invention, the fixing temperature is evaluated by changing the contents of the control EP-ROM). Image formation was carried out, and the glossiness, paper winding and offset when the fixing temperature was 140 ° C., and glossiness, paper winding and offset when the fixing temperature was 200 ° C. were evaluated.

  The above-mentioned binder resin No. 2-No. 13 and binder resin no. In the same manner as in Example 1 using No. 1 (however, only the type of polyethylene wax was changed as described below), the toners of Examples 2 to 6 and Comparative Examples 1 to 8 were prepared. Similarly, a two-component developer was formed, and image formation was performed using a remodeling machine of a color printer LS-8000C (manufactured by Kyocera Corporation) in the same manner as in Example 1, and the glossiness when the fixing temperature was 140 ° C. Winding and offset, glossiness when the fixing temperature was 200 ° C., paper winding and offset were evaluated.

  The types of polyethylene wax used in the production of the toners of the examples and comparative examples were PE20, manufactured by Kato Yoko Co., Ltd., Example 3 and Example 5, C60, manufactured by Kato Yoko Co., Ltd. Example 4 is Hi-Mic-1070, manufactured by Nippon Seiki Co., Ltd., Comparative Example 2 is polywax 1000, manufactured by Toyo Petrolite Co., Ltd., Comparative Example 3 is polywax 655, manufactured by Toyo Petrolite Co., Ltd., and Comparative Example 5 is POLYCOAT- 3030, manufactured by Nippon Seiki Co., Ltd., Comparative Example 6 manufactured by Petlite C9500, manufactured by Toyo Petrolite Co., Ltd., Comparative Example 7 manufactured by Ceramer 5005, manufactured by Toyo Petrolite Co., Ltd., Comparative Example 8 manufactured by Sesylene Wax 140, manufactured by Kato Yoko Co., Ltd. .

  In order to confirm whether the endothermic peak in the DSC curve is due to wax or not, the measurement results of the toner, the toner without added wax and the wax alone were compared, and it was determined that the endothermic peak was due to wax. did.

  In each Example and Comparative Example, the molecular weight distribution of the obtained toner, the toner softening point, and the endothermic peak temperature at the time of temperature rise corresponding to the release agent are shown in Table 1 described later.

The evaluation criteria of the above examples and comparative examples are as follows.
(Glossiness of Image) The medium gloss image of the present invention has a glossiness of 7 to 20, and the glossiness at fixing temperatures of 140 ° C. and 180 ° C. was measured. For the measurement, A4 size paper (Fuji Xerox Co., Ltd., C2 paper, 70 g paper) was used, and the short side was the transport direction. The image used for the measurement is three solid images of 3 x 3 cm on the line connecting the midpoints of the short sides of the paper, the center of which is placed on the line, and the center of the central solid image is the center of the paper The distance between the centers of the images was 10 cm. The toner amount of the solid image was 0.7 mg / cm ² . The measurement was performed at three locations for one solid image, and the average value of the five solid image portions was defined as the glossiness. When the temperature was within 7 to 20 at either temperature, it was rated as ◯, and when it was not at either temperature, it was marked as x. The glossiness is measured with a solid image portion using a gloss meter (Nippon Denshoku PG-1M) at an incident angle of 60 degrees according to the JIS-Z8741 60-degree specular gloss measurement method.
(Offset) Image formation was carried out at a fixing temperature of 140 ° C. and 180 ° C., and it was confirmed whether or not toner was adhered to the fixing roller. . An offset at 140 ° C. was a cold offset, and an offset at 180 ° C. was a hot offset. For the offset measurement, A4 size paper (Fuji Xerox Co., C2 paper, 70 g paper) was used, and the short side was set as the transport direction. The image used for the measurement has three 3 × 3 cm solid images arranged on the line connecting the midpoints of the long sides of the paper so that the center is on the line. The center solid image has its center at the center of the paper. The distance between the centers of the images was set to 7 cm, together with the center. The toner amount of the solid image was 0.7 mg / cm2.
The solid image (paper wrapping) is fixed on the entire surface of the paper (however, the margin is 4 mm). The fixing temperature was set to 140 ° C. and 200 ° C. For the measurement, A4 size paper (L paper, manufactured by Fuji Xerox Co., Ltd., 64 g paper) was used, and the short side of the paper was used as the transport direction. When the toner amount per solid unit area is 1.8 mg / cm ² or more and paper does not wrap around the fixing roller, ○, when winding occurs at 1.5 mg / cm ² or more and below 1.8 mg / cm ² △, the case where winding occurred at less than 1.2 mg / cm ² was taken as x.
The results are shown in Table 1.

When Mw / Mn is low, the glossiness becomes too high when the fixing temperature is 200 ° C., hot offset occurs, and paper wrapping occurs at an acceptable level. When Mw / Mn is high, the glossiness becomes too low when the fixing temperature is 200 ° C., and cold offset occurs. If the peak molecular weight of the main component is less than 8 × 10 ³ , the glossiness becomes too high, hot offset occurs, and paper wrapping occurs at an acceptable level. When the peak molecular weight of the main component is larger than 5 × 10 ⁴ , the glossiness becomes too low and a cold offset occurs. If the proportion of the component having a molecular weight of 1 × 10 ³ or less exceeds 10% by weight, the glossiness becomes too high, hot offset occurs, and paper wrapping occurs at an acceptable level. When the proportion of the component having a molecular weight of 2 × 10 ⁵ or more exceeds 7% by weight, the glossiness becomes too low and a cold offset occurs. When Tm-Wp is smaller than 10, a cold offset occurs and paper wraps. If Tm-Wp is greater than 60, hot offset occurs and paper wrapping occurs at an acceptable level. On the other hand, in the present invention, even when the fixing temperature is changed in a wide range of 140 ° C. and 200 ° C., an intermediate gloss image (glossiness of 7 to 20) can be obtained, and no offset occurs.

  As described above in detail, the full-color image forming apparatus using the full-color toner of the present invention and the image forming method using the same can obtain an appropriate gloss and can be offset without applying oil to the fixing device. In addition, it is possible to form an image in which no paper wrapping occurs.

The molecular weight distribution map measured by GPC which is an example for demonstrating the peak of the main component which concerns on this invention.

Claims (6)

With use of the toner for full color having at least a binder resin and a colorant, the fixing temperature is a full-color image forming apparatus according to electrophotography having a fixing device and is generally in the range of 140 to 200 ° C., the full A full-color image forming apparatus , wherein the toner for toner satisfies the following constituents (a) to (h):
(A) The full-color toner uses a styrene-acrylic resin as a binder resin, and an acrylic monomer component in the styrene-acrylic resin includes methyl acrylate, ethyl acrylate, propyl acrylate, And at least one acrylate ester consisting of butyl acrylate.
(B) The toner has at least one peak in the (weight average) molecular weight distribution measured by GPC.
(C) The molecular weight distribution has a main peak in a region having a molecular weight of 6 × 10 ^{3 to} 6 × 10 ⁴ .
(D) In the molecular weight distribution, the ratio of the component having a molecular weight of 1 × 10 ³ or less to the whole toner is 10% by weight or less.
(E) In the molecular weight distribution, the ratio of the component having a molecular weight of 2 × 10 ⁵ or more to the whole toner is 7% by weight or less.
(F) In the molecular weight distribution, when the weight average molecular weight is Mw and the number average molecular weight is Mn, the value of Mw / Mn is 2 ≦ Mw / Mn ≦ 15.
(G) The toner softening point is Tm (° C.), and the DSC curve measured by the differential scanning calorimeter of the toner is the endothermic peak temperature at the time of temperature rise corresponding to the release agent is Wp (° C.). Sometimes 10 ≦ Tm−Wp ≦ 60.
(H) When a solid image is formed, the glossiness (according to JIS-Z8741 60-degree specular gloss measurement method / incident angle: 60 degrees) in the solid image is a value within the range of 7-20. The full-color image forming apparatus according to claim 1, wherein the styrene-acrylic resin is obtained by polymerizing a monomer solution containing styrene and butyl acrylate.   The full-color image forming apparatus according to claim 1, wherein the fixing device is an oilless fixing device. A full-color image forming method by electrophotography using a full-color toner having at least a binder resin and a colorant, and a fixing temperature in the fixing device within a range of 140 to 200 ° C.,
The full- color image forming method , wherein the full-color toner satisfies the following constituents (a) to (h) :
(A) The full-color toner uses a styrene-acrylic resin as a binder resin, and an acrylic monomer component in the styrene-acrylic resin includes methyl acrylate, ethyl acrylate, propyl acrylate, And at least one acrylate ester consisting of butyl acrylate.
(B) The toner has at least one peak in the (weight average) molecular weight distribution measured by GPC.
(C) The molecular weight distribution has a main peak in a region having a molecular weight of 6 × 10 ^{3 to} 6 × 10 ⁴ .
(D) In the molecular weight distribution, the ratio of the component having a molecular weight of 1 × 10 ³ or less to the whole toner is 10% by weight or less.
(E) In the molecular weight distribution, the ratio of components having a molecular weight of 2 × 10 ⁵ or more to the entire toner is 7% by weight or less.
(F) In the molecular weight distribution, when the weight average molecular weight is Mw and the number average molecular weight is Mn, the value of Mw / Mn is 2 ≦ Mw / Mn ≦ 15.
(G) The toner softening point is Tm (° C.), and the DSC curve measured by the differential scanning calorimeter of the toner is the endothermic peak temperature at the time of temperature rise corresponding to the release agent is Wp (° C.). Sometimes 10 ≦ Tm−Wp ≦ 60.
(H) When a solid image is formed, the glossiness (according to JIS-Z8741 60-degree specular gloss measurement method / incident angle: 60 degrees) in the solid image is a value within the range of 7-20. The full-color image forming method according to claim 4, wherein the styrene-acrylic resin is obtained by polymerizing a monomer solution containing styrene and butyl acrylate.   The full-color image forming method according to claim 4, wherein the fixing device is an oilless fixing device.

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