JP2003255616A - Full-color toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a full-color toner with satisfactory fixing property while obtaining proper gloss. <P>SOLUTION: In the full-color toner comprising at least a binder resin and a colorant is characterized in that a styrene-acryl resin is used for the binder resin, the molecular weight distribution of the toner measured by GPC shows at least one peak and a peak of the main component in the region from 8×10<SP>3</SP>to 5×10<SP>4</SP>molecular weight, the proportion of the component having ≤1×10<SP>3</SP>molecular weight is ≤7 wt.% in the whole toner and the proportion of the component having ≥2×10<SP>5</SP>molecular weight is ≤7 wt.%, and the ratio Mw/Mn, wherein Mw is the weight average molecular weight and Mn is the number average molecular weight, satisfies 2≤Mw/Mn≤10. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a full-color toner for electrophotography and the like, and more particularly to a full-color toner using a styrene-acrylic resin as a binder resin. . 2. Description of the Related Art In recent years, image forming apparatuses using electrophotography, such as copying machines and printers, use three primary color toners of yellow, magenta and cyan in addition to a conventional monochrome image using only black toner. Many full-color copying machines, full-color printers, and the like, which can use the color toner and the black toner to appropriately reproduce various colors by using the color toner and the black toner appropriately, are found on the market. Many of the full-color images created by the above-described apparatus have a luminous and high gloss. On the other hand, the thermal efficiency is high and the operating temperature is 160 to
A roller fixing method has been widely used in image forming apparatuses ranging from a low-speed apparatus to a high-speed apparatus as a fixing apparatus because of its relatively low temperature of 200 ° C., excellent safety, and downsizing of the apparatus. In this roller fixing method, generally, a transfer sheet is passed between upper and lower fixing rollers with a built-in heater, and toner is melted and fixed on the transfer sheet while the transfer sheet passes through the upper and lower fixing rollers. The gloss depends on the fixing temperature described above. [0004] Recently, in business use, a medium gloss image having moderate gloss has been demanded as a full color image instead of a high gloss image. The characteristics of the medium gloss image are that the characters are easy to see, and that the image is bright and the glare is suppressed. In addition, a toner that can be fixed at a lower fixing temperature has been desired due to a demand for reduction of energy and the like. Hitherto, a full-color toner using a polyester resin as a binder resin has been developed so as to obtain the above-mentioned medium gloss image. on the other hand,
From the viewpoint of environmental stability and cost, it is conceivable to produce a full-color toner using a styrene-acrylic resin as a binder resin (for example, Patent Document 1). [0006] However, when a full-color toner is manufactured using a conventionally used styrene-acrylic resin, only low gloss can be obtained. And a desired medium gloss image cannot be obtained. Further, a so-called offset in which toner adheres to the fixing roller occurs. SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has as its object to use a styrene-acrylic resin as a binder resin and provide an appropriate gloss. An object of the present invention is to provide a full-color toner that does not cause offset while obtaining it. According to the present invention, a full-color toner having at least a binder resin and a colorant is measured by GPC using a styrene-acrylic resin as the binder resin. In the molecular weight distribution of the toner, the toner has at least one peak and a molecular weight of 8 × 10 ³
A toner having a main peak in a region of about 5 × 10 ⁴ and a component having a molecular weight of 1 × 10 ³ or less in a total amount of toner of 7% by weight or less and a molecular weight of 2 × 10 ⁵ or more When the weight ratio is 7% by weight or less and the weight average molecular weight is Mw and the number average molecular weight is Mn, Mw
A full-color toner is provided, wherein the value of / Mn is 2 ≦ Mw / Mn ≦ 10. DETAILED DESCRIPTION OF THE INVENTION With a full-color toner using a styrene-acrylic resin which has been studied, only an image having a low glossiness can be obtained. On the other hand, in order to obtain a medium gloss image desired for business use, it is considered that the molecular weight of the toner is greatly involved. It is thought that if the molecular weight of the toner is reduced, the viscosity of the toner can be reduced and a medium gloss image can be obtained. Occurred. Further, even if the characteristics of a full-color toner using a polyester resin as a binder resin capable of obtaining a medium gloss image can be applied to a styrene-acrylic resin as it is, the same performance cannot be obtained. Therefore, the present inventors have conducted intensive studies as to whether a medium gloss image can be obtained depending on the distribution degree and the peak position in the molecular weight distribution of the toner, and as a result, there is a peak having the largest area in a specific range,
By setting the molecular weight distribution of the toner to a specific distribution such as whether it is broad (the molecular weight width where the toner particles are present is wide) or sharp (the molecular weight width where the toner particles are present is relatively narrow), While obtaining a glossy image,
It has been found that a toner free of offset can be obtained. As a result, it became possible to correspond to various machine specifications. The toner of the present invention can be produced by a method known per se such as a pulverization classification method, a melt granulation method, a spray granulation method, and a suspension / emulsion polymerization method. The pulverization classification method can be suitably used. In such a 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 is premixed with a Henschel mixer or a V-type mixer, and then a twin-screw extruder is used. Is melt-kneaded using the melt-kneading apparatus described in (1). After cooling the melt-kneaded product, it is roughly pulverized and finely pulverized, and if necessary, classified to obtain toner particles having a predetermined particle size distribution. If necessary, the surface of the toner particles is treated with a surface treating agent to obtain a toner. In order to obtain a high-quality image, the volume center particle diameter of the toner is preferably 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 monomer serving as the base of the styrene-acrylic resin include styrene derivatives such as styrene, α-methylstyrene, p-methylstyrene, pt-butylstyrene, p-chlorostyrene, and hydroxystyrene; methacrylic acid, methyl (Meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, glycidyl (meth) acrylate, methoxyethyl (meth) acrylate, propoxyethyl (meth) acrylate, methoxydiethylene glycol (meth) acrylate, Ethoxydiethylene glycol (meth) acrylate, benzyl (meth) acrylate, cyclohexyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, (meth) acrylonitrile, (meth) Acrylamide, N-methylol (meth) acrylamide, ethylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, trimethylolethanetri (meth) acrylate And the like. The mixture of the above-mentioned various monomers can be polymerized by any method such as solution polymerization, bulk polymerization, emulsion polymerization, suspension polymerization, etc. to obtain the binder resin used in the present invention. In such polymerization, acetyl peroxide, decanoyl peroxide, lauroyl peroxide, benzoyl peroxide, azobisisobutyronitrile, azobisisobutyronitrile, 2,2′-azobis-2,4-dimethylvaleronitrile, A known polymerization initiator such as 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile 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 G
It is measured as follows using PC (gel permeation chromatography). GPC for measurement
The apparatus is HLC-8220GPC manufactured by Tosoh Corporation, and the column is TFKgel GMHxl (dual) manufactured by Tosoh Corporation. 100 mg of the toner and 20 ml of THF (tetrahydrofuran) are mixed, and the mixture is stirred by a ball mill or the like until it is uniformly dissolved. Thereafter, the supernatant separated by the centrifuge is used as a GPC sample. The toner concentration in the sample is
1-10 mg / ml is preferred. In the measurement, THF was used as a solvent and GP
After stabilizing the column of the C apparatus at 40 ° C., the column is flowed at this temperature at a flow rate of 1 ml / min, and about 100 μl of a THF sample solution (concentration: 2 mg / ml) is injected for measurement. The molecular weight distribution of the sample is calculated from the relationship between the logarithmic value of a calibration curve prepared using several types of monodisperse polystyrene standard samples and the count number. As a standard polystyrene sample for preparing a calibration curve, for example, polystyrene having a molecular weight of 5 to 1,000,000 can be used. As the column, a styrene-divinylbenzene-based polymer column or the like can 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 and shoulder of the curve in this molecular weight distribution map. The portion between such straight lines is defined as the peak area or 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 peak of the main component. This example is an example for explaining the peak, and the molecular weight of the peak of 4 is about 4000, which does not fall within the scope of the claims of the present invention. If the peak of the main component is too high in the high-molecular range, the toner becomes difficult to melt at a low fixing temperature, and the adhesive strength between the melted toner and the unmelted toner is weakened.
A so-called cold offset occurs. Also,
Since the elasticity is strong, the surface of the fixed image becomes rough, and the glossiness of the image decreases. Conversely, if the peak of the main component is too low in the low molecular weight region, when the fixing temperature is high, the elasticity of the toner is weakened, and the adhesion between the toners is weakened.
A so-called hot offset occurs. Further, when the elasticity of the toner is weak, the toner is more easily crushed by the fixing roller at the time of fixing, the surface of the fixed image becomes smooth, and the glossiness of the image becomes too high. Further, even if the molecular region where the peak of the main component exists is in an appropriate range, it is not possible to obtain a medium gloss image without widening the range in which the fixing temperature is not offset even at a high or low temperature. Even if the peak of the main component exists in an appropriate molecular region, if too many toner particles are present in a lower molecular region or a higher molecular region, it will be difficult to dissolve even at a low or high fixing temperature, and offset. Is likely to occur, and the temperature range in which fixing can be performed is narrowed. As a result of repeated experiments, the inventors having obtained the above viewpoints have at least one peak, the toner has a main component peak in a region of a molecular weight of 8 × 10 ^{3 to} 5 × 10 ⁴ , and The proportion of the component having a molecular weight of 1 × 10 ³ or less to the whole toner is 7% by weight or less, and the molecular weight is 2 × 1 ³ or less.
0 percentage of the total toner ⁵ or more ingredients is not more than 7 wt%, Mw a weight average molecular weight, a number average molecular weight Mn
When the value of Mw / Mn was 2 ≦ Mw / Mn ≦ 10, it was possible to obtain a desired fixing temperature range while obtaining a medium gloss image. The peak of the main component of the toner has a molecular weight of 8 × 10
^If the area is lower than ^{3 to} 5 × 10 ⁴ , the glossiness becomes too high or hot offset occurs. The peak of the main component of the toner has a molecular weight of 8 × 10 ^{3 to} 5 ×.
To be in the region higher than ¹⁰⁴ regions, gloss is too low, cold offset occurs. If the proportion of components having a molecular weight of 1 × 10 ³ or less in the whole toner exceeds 7% by weight, hot offset occurs, and the proportion of components having a molecular weight of 2 × 10 ⁵ or more in the whole toner exceeds 7% by weight. Then, a cold offset occurs. When the value of Mw / Mn is smaller than 2, hot offset occurs. When the value of Mw / Mn is larger than 10, a cold offset occurs. The molecular weight distribution of the toner in the present invention can be adjusted by adjusting the molecular weight distribution of the styrene-acrylic resin as the binder resin by the molecular weight of the basic monomer, or by the melt-kneading step of preparing the toner. By adjusting the temperature and kneading conditions. The binder resin used has a glass transition temperature of 55.
Those having a temperature range of -65 ° C are preferred. Glass transition temperature is 5
If the temperature is lower than 5 ° C., the toner may harden in the developing device or the toner cartridge. On the other hand, if the temperature is higher than 65 ° C., the toner may not be sufficiently fixed on a transfer material such as paper. As the coloring agent to be contained in the binder resin,
For example: Colorant for black toner: carbon black, acetylene black, lamp black, aniline black and the like. 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. Pigment Yellow 17, C.I. I. Pigment yellow 180, C.I. I. Pigment Yellow 74,
C. 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 loess; I. Nitro dyes such as Acid Yellow 1; I. Solvent Yellow 2,
C. 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 4
9, 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. Basic Red 10, C.I. I. Disperse Red 15 etc. Colorant for cyan toner: C.I. I. Pigment Blue 1
5, 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. Further, a charge control agent can be contained as required. Known charge control agents can be used as the charge control agent. Examples of the positive charge control agent include a nigrosine dye, a fatty acid-modified nigrosine dye, a carboxyl group-containing fatty acid-modified nigrosine dye, a quaternary ammonium salt, and an amine-based charge control agent. Compounds, organometallic compounds and the like can be used, and as the negatively chargeable charge control agent, metal complexes of oxycarboxylic acid, metal complexes of azo compounds, metal complex salt dyes and salicylic acid derivatives can be used. Further, a release agent can be contained as required. As the release agent, conventionally known waxes, for example, paraffin wax, petroleum wax, polyethylene wax, polypropylene wax, aliphatic hydrocarbon wax such as polyethylene oxide, montan wax, carnauba wax, beeswax, wood wax and the like Used. These release agents have a melting point of 50 to 140.
C., preferably 70 to 120.degree. Also,
The content of these release agents is usually 100 binder resin components.
The amount is preferably 1 to 20 parts by weight, particularly preferably 3 to 10 parts by weight per part by weight. Further, a surface treatment agent can be used if necessary. Examples of the surface treatment agent include silica, alumina, and the like in order to adjust the charge controllability and fluidity of the toner.
Inorganic fine powders such as titanium oxide, zinc oxide, magnesium oxide and calcium carbonate; organic fine powders such as polymethyl methacrylate; fatty acid metal salts such as zinc stearate; and the like. Can be used together. The addition amount of the surface treatment agent is preferably in the range of 0.1 to 2.0% by weight per toner particle. The mixing of the surface treating agent and the toner particles can be performed 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. The carrier used when used as a two-component developer is not limited. For example, magnetic metals such as iron, nickel, and cobalt and alloys thereof, or alloys containing rare earth elements, hematite, magnetite, manganese-zinc based Sintering and atomizing magnetic materials such as soft ferrites such as ferrite, nickel-zinc ferrite, manganese-magnesium ferrite, and lithium ferrite, and iron-based oxides such as copper-zinc ferrite and mixtures thereof. The magnetic particles produced as described above, and those obtained by coating the surfaces of the magnetic particles with a resin can be used. The particle size of the carrier is generally from 30 to 200 μm, particularly from 40 to 15 μm, expressed as a particle size by electron microscopy.
Those having a thickness of 0 μm are preferred. The apparent density of the carrier varies depending on the composition and the surface structure of the magnetic material when the magnetic material is mainly used, but is generally 2.4 to 3.0 g / carrier.
A range of cm ³ is preferred. As the medium gloss image in the present invention, a gloss meter (PG-1M manufactured by Nippon Denshoku Co., Ltd.) was used, and the viewing angle was 60 °.
When the value measured in degrees is the gloss, 7 to 20 is desired. EXAMPLES Production Example 1 of Binder Resin A monomer solution comprising 70 parts by weight of styrene and 30 parts by weight of butyl acrylate was mixed with V-65 (2,2) as a polymerization initiator.
6 parts by weight of 2'-azobis- (2,4-dimethylvaleronitrile), manufactured by Wako Pure Chemical Industries, Ltd. and toluene 2 as a solvent
Into a solution containing 00 parts by weight (equipped with a condenser and refluxing toluene) was added dropwise over 3 hours.
After polymerization for 12 hours while maintaining the temperature at 0 ° C., toluene was removed by distillation under reduced pressure, and the binder resin for toner No. 1 of Example 1 shown in Table 1 was used. 1 was obtained. 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, Ltd.). The binder resin No. for toner of Example 2 shown in Table 1 was produced in the same manner as in Production Example 1 except that the polymerization reaction was carried out for 12 hours while increasing the temperature by 4 ° C. per hour. 2
Got. Production Example 3 of Binder Resin Production was conducted except that the polymerization initiator was 4 parts by weight of V65 (2,2'-azobis- (4-methoxy-2,4-dimethylvaleronitrile), manufactured by Wako Pure Chemical Industries, Ltd.). In the same manner as in Example 1, the binder resin No. for toner of Example 3 shown in Table 1 was used. 3 was obtained. Production Example 4 of Binder Resin: 2 parts by weight of V59, 3 parts by weight of V65,
70 (2,2'-azobis- (2-dimethylvaleronitrile), manufactured by Wako Pure Chemical Industries, Ltd.). No. for binder resin 4 was obtained. Production Example 5 of Binder Resin 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 carried out for 12 hours while increasing the temperature by 4 ° C. per hour. Similarly to Table 1, the binder resin No. for toner of Comparative Example 1 shown in Table 1 was used. 5 was obtained. Preparation Example 6 of Binder Resin The toner of Comparative Example 2 shown in Table 1 was prepared in the same manner as in Preparation Example 1, except that the polymerization initiator was a mixture of 2 parts by weight of V59 and 2 parts by weight of V70.
No. for binder resin 6 were obtained. Production Example 7 of Binder Resin The same procedure as in Production Example 1 was repeated except that the polymerization initiator was a mixture of 2 parts by weight of V59 and 6 parts by weight of V-65. Binder resin No. for toner 7 were obtained. Production Example 8 of Binder Resin Binder resin No. 4 for toner of Comparative Example 4 shown in Table 1 was prepared in the same manner as in Production Example 1 except that the polymerization initiator was changed to 3 parts by weight of V70. 8 were obtained. Production Example 9 of Binder Resin Binder resin No. 5 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 8 parts by weight of V59. 9 were obtained. Preparation Example 10 of Binder Resin The polymerization initiator was V-6
No. 5 was used in the same manner as in Production Example 1 except that 3 parts by weight of V70 and 1 part by weight of V70 were mixed. 10 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;
After mixing 4 parts by weight of a cyan pigment (PB15-3, manufactured by Ciba-Gaiki) as a colorant and 5 parts by weight of polyethylene wax (UMEX 100TS, manufactured by Sanyo Chemical) as a release agent, using a Henschel mixer, the mixture was extruded by twin screw. The mixture was melt-kneaded in a mixer to prepare a resin composition for toner. The obtained resin composition for toner was finely pulverized by an air-flow type pulverizer and classified by an air classifier to obtain toner particles having an average particle size of 8 μm on a volume basis. With respect to 100 parts by weight of the toner particles, 0.5 parts by weight of hydrophobic silica (TG820, manufactured by Cabot Corporation) as a surface treatment agent and titanium oxide (EC-100T,
0.8% by weight of Titanium Kogyo Co., Ltd.) and mixed with high stirring with a Henschel mixer to obtain a toner. This toner was blended with a ferrite carrier (EF-60B, manufactured by Powder-Tech Co., Ltd.) having an average particle diameter of 80 μm, the surface of which was coated with a silicone resin, so that the toner concentration became 5% by weight. This was a system developer. The molecular weight distribution of the obtained toner is described in Table 1 described later. For the developer of the first embodiment, a modified color printer LS-8000C (manufactured by Kyocera Corp.) was used (using the toner of the present invention), and the fixing temperature was controlled by EP-RO for control.
M is changed, and the image is formed by using (evaluation), and the glossiness and offset when the fixing temperature is set to 140 ° C.
The glossiness and offset when the fixing temperature was 180 ° C. were evaluated. The above binder resin No. 2-No. 10 and the binder resin No. After producing a toner in the same manner as in Example 1 using the toner No. 1, a two-component developer was formed in the same manner as in Example 1, and the color printer LS-8000C was manufactured as in Example 1.
An image was formed using a modified machine (manufactured by Kyocera Corporation), and the gloss and offset when the fixing temperature was 140 ° C. and the gloss and offset when the fixing temperature was 180 ° C. were evaluated. The evaluation criteria of the above Examples and Comparative Examples are as follows. (Glossiness of Image) The glossiness of the medium gloss image of the present invention was 7 to 20, and the glossiness was measured at fixing temperatures of 140 ° C. and 180 ° C. For the measurement, A4 size paper (Fuji Xerox Co., Ltd., C2 paper, 70 g paper) was used, and the short side was set as the transport direction.
The image used for the measurement is 3x on the line connecting the midpoints of the short sides of the paper.
Three 3 cm solid images were arranged such that their centers were on the line, and the center of the center solid image was aligned with the center of the paper, and the interval between the image centers was 10 cm. The toner amount of the solid image was 0.7 mg / cm ² . The measurement was performed at three places for one solid image, and the average value of the five solid image portions was defined as the glossiness. When both temperatures were within the range of 7 to 20, it was evaluated as ○, and when neither temperature was within, it was evaluated as ×. The glossiness of the solid image portion is measured using a gloss meter (PG-1M manufactured by Nippon Denshoku Co., Ltd.) at an incident angle of 60 degrees according to JIS-Z8741 60-degree specular glossiness measurement method. Further, (offset) image formation was performed at fixing temperatures of 140 ° C. and 180 ° C., and it was confirmed whether toner was adhered to the fixing roller for each. And The offset at 140 ° C. was defined as a cold offset, and the offset at 180 ° C. was defined as a hot offset. A4 size paper (Fuji Xerox Co., Ltd., C2
Paper, 70 g paper) and the short side was set as the transport direction. The images used for the measurement are arranged on a line connecting the midpoints of the long sides of the paper with three solid images of 3 × 3 cm, the center of which is on the line,
The center of the solid image was aligned with the center of the sheet, and the interval between the centers of the images was 7 cm. The toner amount of the solid image was 0.7 mg / cm ² . Table 1 shows the results. [Table 1] When Mw / Mn is low, the glossiness becomes too high at a fixing temperature of 180 ° C., and hot offset occurs. When Mw / Mn is high, the glossiness becomes too low when the fixing temperature is 180 ° C., and a cold offset occurs. If the peak molecular weight of the main component is smaller than 8 × 103, the glossiness becomes too high, and hot offset occurs. If 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 ratio of the components having a molecular weight of 1 × 10 ³ or less to the whole exceeds 7% by weight, the glossiness becomes too high and hot offset occurs. If the ratio of the components having a molecular weight of 2 × 10 ⁵ or more to the whole exceeds 7% by weight, the glossiness becomes too low and a cold offset occurs. On the other hand, in the present invention, even if the fixing temperature was changed in a wide range of 140 ° C. and 180 ° C., a medium gloss image (gloss degree 7 to 20) could be obtained, and no offset occurred. As described in detail above, by using the full-color toner of the present invention, it is possible to form an image free from offset while obtaining an appropriate gloss.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing a molecular weight distribution measured by GPC as an example for explaining a peak of a main component according to the present invention.

Claims (1)

Claims: 1. A full-color toner having at least a binder resin and a colorant, wherein a styrene-acrylic resin is used as the binder resin, and a molecular weight distribution (weight average) of the toner measured by GPC. (Molecular weight), at least one peak, a main peak in a molecular weight region of 8 × 10 ^{3 to} 5 × 10 ⁴ , and a ratio of a component having a molecular weight of 1 × 10 ³ or less to the entire toner. 7% by weight or less and a molecular weight of 2 × 1
0 percentage of the total toner ⁵ or more ingredients is not more than 7 wt%, Mw a weight average molecular weight, a number average molecular weight Mn
Wherein the value of Mw / Mn satisfies 2 ≦ Mw / Mn ≦ 10.