JP2002365832A - Toner for developing electrostatic charge image and image forming method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner for developing an electrostatic charge image, with which an excellent image can be stably obtained even in a low temperature fixing process. SOLUTION: In the image forming method, which uses two-component developer consisting of toner, which contains at least a binder resin, wax and colorant, and carrier, and uses an electrophotographic image forming device using oil-less fixing whose bearing (a roller load/a contact area) at a fixing time is <=1.5×10<5> Pa, system speed is defined as 150-760 mm/sec, and the developer stirring time of one copy per one original sheet is equal to or longer than four seconds, and the developer stirring time of one copy per one original sheet is twice to eight times of the developer stirring time per one copy in a successive copying process. The toner for developing the electrostatic charge image is used for any of claims 1-7, and has the coefficient of surface friction at the time of press-molding the toner into a plate shape is >=0.2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrostatic image developing toner used for developing an electrostatic latent image in an image forming method such as an electrophotographic method, an electrostatic recording method, and an electrostatic printing method.

[0002]

2. Description of the Related Art Conventionally, in electrophotography, a photoconductive substance is generally used to form an electric latent image on a photoreceptor by various means, and then the latent image is developed using toner. After transferring the toner powder image to paper etc. as necessary,
The image is fixed by heating, pressurizing or solvent vapor to obtain a copy image.

As a method for heat-fixing a toner image on transfer paper, heating roller fixing is widely and generally used because of its high energy efficiency. In recent years, energy saving has progressed more and more, and in some cases, the heat source is turned off during standby without fixing. In such an apparatus, the heat roller is heated immediately after the heat source is turned on, and it is necessary to reach a desired temperature in an extremely short time. For this reason, attempts have been made to reduce the thickness of the fixing roller on the side in contact with the toner image support surface in order to increase the thermal energy efficiency of the fixing device used in such an apparatus. This makes it possible to reach a desired temperature in a very short time.

However, by reducing the thickness of the fixing roller, the mechanical strength of the roller itself is reduced, and a large load is not applied between the rollers. In order to actually operate such a fixing device without hindrance, the toner must be capable of fixing at a low temperature that is incomparable with conventional toner. In recent years, the necessity for low-temperature fixing has further increased, and when the above-described thin-walled roller and low-load fixing device are actually used, sufficient low-temperature fixing ability and fixing temperature range with the conventional technology are required. It is difficult to achieve both security and heat preservation.

[0005] As for the toner used for the above-mentioned low-temperature fixing, it has been generally attempted to improve the low-temperature fixing property by using a resin or wax having a low softening point. Above all, the amount of wax on the surface of the toner greatly affects the releasability of the toner at the time of fixing. If the amount of the wax exposed on the toner surface is large, the releasability by the wax is increased by heating at the time of fixing, which is effective in terms of offset resistance. However, at the same time, there is a problem that the wax is spent on the carrier or migrates to the photosensitive member or the developing sleeve to cause filming, thereby preventing a good image quality from being obtained. Furthermore, such a low-temperature fixing toner is hardened by the heat of the machine used and the heat at the time of storage because it is thermally weak.
It is known to cause so-called blocking.

In recent years, many copying machines have a printer function, so that the output of only one copy or print increases, and the stirring time of the developer in the development increases with respect to the number of copies and prints. Is coming. In particular, one copy is used for one manuscript (commonly known as 1 to 1).
In the case of the (copy, low duty mode) mode, the rotation time is required to be 2 to 8 times as long as the development rotation time per copy in continuous copying. In such a mode, the thermal stress generated between the developer and the developer regulating member when the developer is agitated is increased, and in addition to blocking, toner is spent on the carrier and the life of the developer is shortened. Relax,
It is susceptible to adverse effects such as filming on the photoreceptor. In recent years, the need for low-temperature fixing has further increased, and furthermore, using a fixing device with a low surface pressure as described above,
In a use environment where the stirring time of the developer is long, it is difficult to achieve a sufficient low-temperature fixing property, a sufficient fixing temperature range, and high heat resistance at the same time with the conventional technology.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a low-pressure fixing roller which has a fixing device with a low surface pressure and has a low-temperature fixing property even in a use environment where the stirring time of the developer is long and the thermal stress on the developer is large. An object of the present invention is to provide a toner for developing an electrostatic image capable of stably obtaining a good image while maintaining high heat resistance while securing an image, and an image forming method using the toner.

[0008]

According to the present invention, there is provided a two-component developer comprising at least a toner containing a binder resin, a wax and a colorant and a carrier, and the surface pressure (roller load / contact area) during fixing is reduced. An electrophotographic image forming apparatus using an oilless fixing of 1.5 × 10 ⁵ Pa or less, with a system speed of 150 to 760 mm / sec and a developer stirring time of one copy per document of 4 seconds or more And the surface friction coefficient when pressed into a plate in a developing device in which the developer stirring time for one copy per original is 2 to 8 times the developer stirring time for one copy in continuous copying. The above problem is solved by using a toner having a value of 0.2 or more.

As a result of intensive studies, the present inventors have found that there is a correlation between the amount of wax present on the surface of toner particles and the coefficient of friction of the toner surface. The greater the amount of wax present on the surface of the toner particles, the lower the coefficient of friction on the toner surface. In the present invention, as a means for measuring the friction coefficient on the surface of the toner particles, the toner is pressure-formed into a plate shape, and the surface is measured. At the same time, the load in the actual machine is substituted by pressurizing, and the stability in the use environment can be known. The value of the toner surface friction coefficient is 0, 2 or more, and 0.20 or more.
More preferably, the value is 40 or less.

When the toner surface friction coefficient is less than 0.20, the amount of wax exposed on the toner surface is large, and the wax is transferred to the carrier or the photosensitive member, causing carrier spent or photosensitive member filming. Cheap. Also, 0.4
When the value exceeds 0, the releasability, which is the original role of the release agent, becomes slightly insufficient, so that hot offset easily occurs. The coefficient of surface friction in the present invention is measured by an automatic friction and wear analyzer D manufactured by Kyowa Interface Science Co., Ltd. as a measuring device.
This is the value of the coefficient of static friction when a FPM-SS type is used and a stainless steel ball is used as a contact.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. In the present invention, it is effective to use carnauba wax, rice wax, or ester wax as the wax dispersed in the toner. These waxes are superior in low-temperature fixability to other waxes.
Carnauba wax is a natural wax obtained from the leaves of carnauba palm, especially those of low acid number type with free fatty acids eliminated can be uniformly dispersed in the binder resin,
It is particularly preferable because filming on the photoreceptor and spent on the charging member are small because the volatile component is small.
Rice wax is a natural wax obtained by refining crude wax produced in a dewaxing or wintering process when refining rice bran oil extracted from rice bran. Synthetic ester wax is synthesized from a monofunctional linear fatty acid and a monofunctional linear alcohol by an ester reaction. These wax components are used alone or in combination. The addition amount of the wax component is preferably 0.5 to 10 parts by weight.

In particular, the content of the wax is generally in the range of 1 to 10 parts by weight based on the toner resin component, but in the present invention, it is 5 parts by weight or less, more preferably 1 part by weight or less.
~ 5 parts by weight is good. If the amount is less than 1 part by weight, the effect as a release agent is not sufficient. If the amount is more than 5 parts by weight, the amount of wax exposed on the toner surface increases, so that the spent on the carrier or the filling on the photoreceptor is increased. Is more likely to occur.

Also, in particular, when the toner contains 5 to 40% of chloroform-insoluble matter, it is possible to obtain a toner having a high latitude in hot offset property without impairing low-temperature fixability in a use environment where there is a lot of heat stress. There was found. Here, when the chloroform-insoluble content is less than 5%, there is a problem in hot offset property. When the chloroform-insoluble content is more than 40%, heat resistance and hot offset property are further improved, but low-temperature fixing property is improved. Was worsened.

In particular, the toner has an average volume particle size of 5 to 5.
10 μm, the content of toner of 5 μm or less is 60 to 80.
It has been found that by having the number%, good fixing properties can be obtained and a good image can be maintained even in a use environment in which thermal stress is high. When the content of the toner having a particle size of 5 μm or less is 60% by number or less, the stability of image quality such as reproducibility of fine lines may be deteriorated. When the content of the toner having a particle size of 5 μm or less is 80% by number or more, the homogenization of the toner is impaired, the charge stability is deteriorated, and the image density may be reduced.

The toner of the present invention preferably contains a polyester resin as a resin component in an amount of 50% by weight or more. Polyester resin In general, polyester resin is a binder resin suitable for the present invention because low-temperature fixing is possible while maintaining heat-resistant storage stability as compared with other resins.

When the toner of the present invention constitutes a two-component developer together with a carrier, it is particularly preferable to use a carrier whose surface is coated with a silicone resin as the carrier. Hitherto, in order to prevent toner spent on the carrier surface, carriers coated with various resins have been proposed, but it has been found that silicon-coated carriers are extremely effective for spent wax.

FIG. 1 shows an example of a fixing device used in the present invention. In the figure, 1 is a fixing roller, 2
Represents a pressure roller. The fixing roller 1 has a surface of a metal cylinder 3 made of a high heat conductor such as aluminum, iron, stainless steel or brass, and has an RTV,
An anti-offset layer 4 such as silicone rubber, tetrafluoroethylene-perfluoroalkyl vinyl ether (PFA), or polytetrafluoroethylene (PTFE) is coated. A heating lamp 5 is disposed inside the fixing roller 1. Metal cylinder 6 of pressure roller 2
In many cases, the same material as that of the fixing roller 1 is used, and an anti-offset layer 7 such as PFA or PTFA is formed on the surface thereof.
Is coated. Although not necessary, a heating lamp 8 is disposed inside the pressure roller 2.
Although not shown, the fixing roller and the pressure roller are pressed against each other by springs at both ends and rotate. The fixing support 1 (transfer paper such as paper) of the toner image T is passed between the fixing roller 1 and the pressure roller 2 to perform fixing.

The fixing device used in the present invention improves the temperature rise characteristics of the fixing roller by setting the thickness of the metal cylinder of the fixing roller to 1.0 mm or less, and can achieve a desired temperature in a very short time. Can be launched. The preferred thickness of the metal cylinder varies depending on the strength and thermal conductivity of the material used, but is 0.2 to 0.7 m.
m is preferred.

The load (surface pressure) applied between the fixing roller and the pressure roller is preferably 1.5 × 10 ⁵ Pa or less. The surface pressure is a value obtained by dividing a load applied to both ends of the roller by a roller contact area. The roller contact area is determined by passing a sheet, such as OHP paper, whose surface properties change greatly due to heating, between rollers heated to the feasible temperature, stopping on the way, holding for several tens of seconds, then discharging, and changing the surface properties. Calculate the area of the place where A higher roller surface pressure is advantageous for fixing a toner image. However, in a fixing device in which the thickness of the metal cylinder of the fixing roller is 1.0 mm or less, a large load is not applied because the roller distortion is caused. The load is 1.5 × 10 ⁵ Pa or less, preferably 0.5 to
It is 1.0 × 10 ⁵ Pa.

Next, the materials used in the toner of the present invention will be described in detail. The polyester resin used in the present invention is obtained by condensation polymerization of an alcohol and a carboxylic acid. Examples of the alcohol used include glycols such as ethylene glycol, diethylene glycol, triethylene glycol, and propylene glycol;
1. etherified bisphenols such as 1.4-bis (hydroxymethyl) cyclohexane and bisphenol A;
Other examples include dihydric alcohol monomers and trihydric or higher polyhydric alcohol monomers. Examples of the carboxylic acid include divalent organic acid monomers such as maleic acid, fumaric acid, phthalic acid, isophthalic acid, terephthalic acid, succinic acid, and malonic acid; 1,2,4-benzenetricarboxylic acid; , 2,5-benzenetricarboxylic acid, 1,2,4
-Cyclohexanetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methylenecarboxypropane, 1,2,7,8-octanetetracarboxylic acid And other trivalent or higher polyvalent carboxylic acid monomers. Here, the glass transition temperature T of the polyester resin
g is preferably 55 ° C. or more, more preferably 60 ° C. or more, from the viewpoint of heat storage properties.

In the present invention, a resin other than the polyester resin may be used as a resin component in the toner in a range that does not impair the performance of the toner. In this case, examples of usable resins include the following, but are not limited thereto. Polystyrene, chloropolystyrene, poly-α-methylstyrene, styrene / chlorostyrene copolymer, styrene / propylene copolymer, styrene / butadiene copolymer, styrene / vinyl chloride copolymer, styrene / vinyl acetate copolymer, styrene / Maleic acid copolymer, styrene / acrylate copolymer (styrene / methyl acrylate copolymer, styrene / ethyl acrylate copolymer, styrene / butyl acrylate copolymer, styrene / octyl acrylate copolymer Coalescence, styrene / phenyl acrylate copolymer, etc.),
Styrene / methacrylic acid ester copolymer (styrene /
Methyl methacrylate copolymer, styrene / ethyl methacrylate copolymer, styrene / butyl methacrylate copolymer, styrene / phenyl methacrylate copolymer), styrene / α-methyl methyl acrylate copolymer, styrene / Styrene resins such as acrylonitrile / acrylic acid ester copolymers (homopolymers or copolymers containing styrene or styrene substituents), vinyl chloride resins, styrene / vinyl acetate copolymers, rosin-modified maleic acid resins, phenolic resins , Epoxy resin, polyethylene resin, polypropylene resin, ionomer resin, polyurethane resin, silicone resin, ketone resin, ethylene / ethyl acrylate copolymer, xylene resin, polyvinyl butyral resin, petroleum resin, hydrogenated petroleum resin, etc. . These resins are not limited to being used alone, and may be used in combination of two or more. In addition, the production method is not particularly limited, and any of bulk polymerization, solution polymerization, emulsion polymerization, and suspension polymerization can be used.

The toner of the present invention may contain a coloring agent, if necessary.
It is also possible to incorporate a charge control agent, another release agent, a fluidity improver, and the like.

Examples of the coloring agent include carbon black, lamp black, iron black, aniline blue, phthalocyanine blue, phthalocyanine green, Hansa Yellow G, rhodamine 6C lake, calco oil blue, chrome yellow, quinacridone, benzidine yellow, rose bengal, Any conventionally known dye or pigment such as a triallylmethane dye or the like can be used alone or in combination, and can be used as a black toner or a full-color toner. The amount of these colorants used is usually 1 to 30% by weight, preferably 3% by weight, based on the toner resin component.
-20% by weight.

As the charge controlling agent, any conventionally known polarity controlling agent such as a nigrosine dye, a metal complex type dye and a quaternary ammonium salt can be used by mixing with a zirconium compound. The amount of the polarity controlling agent is 0.1 to 10 parts by weight, preferably 0.5 to 10 parts by weight, based on the toner resin component.
-5 parts by weight. Here, the general production method of the zirconium compound of the present invention can be obtained by reacting with water or / and an organic solvent using a metal-imparting agent, and filtering and washing the product. In the case of a tetravalent cation, a metal imparting agent that can be used for producing the compound of the present invention is a halogenated zirconium compound such as ZrCl ₄ , ZrF ₄ , ZrBr ₄ , ZrI ₄ , Zr (OR) ₄ (R Represents an alkyl group, an alkenyl group, or the like) or Zr (SO ₄ ) ₂
And the like. In the case of a divalent cation of an oxo compound, ZrOCl ₂ , ZrO
(NO ₃ ) ₂ , ZrO (ClO ₄ ) ₂ , H ₂ ZrO (SO ₄ )
₂ , ZrO (SO ₄ ) .Na ₂ SO ₄ , ZrO (HPO ₄ ) ₂
Inorganic acid zirconium compounds such as ZrO (CO ₃ ),
(NH ₄ ) ₂ ZrO (CO ₃ ) ₂ , (NH ₄ ) ₂ ZrO (C _{2
H 3 O 2) 2, ZrO} (C 2 H 35 O 2) 2, ZrO (C 18 H 35
And organic acid zirconium compounds such as O ₂ ) ₂ .

In the present invention, any known release agent can be used for the toner. In particular, it is preferable to use carnauba wax, montan wax and rice oxide wax alone or in combination. it can. The carnauba wax is preferably a microcrystalline wax, and preferably has an acid value of 5 or less and a particle diameter of 1 μm or less when dispersed in a toner binder. The montan wax generally refers to a montan-based wax refined from a mineral, and is preferably a microcrystal and has an acid value of 5 to 14 like carnauba wax. The oxidized rice wax is obtained by oxidizing rice bran wax with air, and preferably has an acid value of 10 to 30. Other release agents include solid silicone varnish,
Any conventionally known mold release agent such as higher fatty acid higher alcohol, montan ester wax, low molecular weight polypropylene wax, etc. can be mixed and used. The amount of these release agents used is 1 to 20 parts by weight based on the toner resin component.
Preferably it is 3 to 10 parts by weight.

As the fluidity improver, any conventionally known fluidity improver such as silicon oxide, titanium oxide, silicon carbide, aluminum oxide and barium titanate can be used alone or as a mixture. The use amount of these fluidity improvers is from 0.1 to 5 parts by weight, preferably from 0.5 to 2 parts by weight, based on the weight of the toner.

As the carrier used when the toner of the present invention is used as a two-component developer, all known carriers can be used. For example, powders having magnetism such as iron powder, ferrite powder and nickel powder, Examples thereof include glass beads and the like, and those obtained by treating the surfaces thereof with a resin or the like.

The resin powder that can be coated on the carrier in the present invention includes a styrene-acrylic copolymer,
Silicone resin, maleic acid resin, fluorine resin, polyester resin epoxy resin and the like are available. In the case of a styrene-acrylic copolymer, those having a styrene content of 30 to 90% by weight are preferred. In this case, if the styrene content is less than 30% by weight, the developing characteristics are low, and if the styrene content exceeds 90% by weight, the coating film becomes hard and easily peels off, shortening the life of the carrier. In addition, the resin coating of the carrier in the present invention may contain an adhesion-imparting agent, a curing agent, a lubricant, a conductive material, a charge control agent, and the like, in addition to the above resin.

(Method of Measuring Physical Properties) (1) Coefficient of friction of toner surface: 3 g of toner is charged into a tableting die and pressed for 1 minute under a load of 6 tons to obtain a diameter of 40 m.
Then, a plate-shaped toner pellet of m is prepared. An automatic friction and wear analyzer (DFPM-S manufactured by Kyowa Interface Science Co., Ltd.)
(S type), the static friction coefficient was measured under the conditions of a point contact method using a stainless steel ball as a contact, a load of 50 g, and a stroke of 10 mm, and this was defined as the toner surface friction coefficient.

(2) Chloroform-insoluble content: For the measurement of chloroform-insoluble content, about 1.0 g of a toner is weighed, and about 50 g of chloroform is added thereto, and a sufficiently dissolved solution is first separated by centrifugation and separated by JIS. (P3801) Filter at room temperature using five kinds of quantitative filter paper. The dried paper residue is weighed and expressed as a ratio (% by weight) between the used resin and the filter paper residue. When the amount of unnecessary chloroform in the binder resin is measured when the toner is used, about 1.0 g of the toner is weighed and the same method as that for the binder resin is used. Is determined separately by thermal analysis.

(3) Volume average particle size: An interface (manufactured by Nikkaki) for outputting a number distribution and a volume distribution to a Coulter Counter TAII manufactured by Coulter Electronics, USA, and a PC 9801 personal computer (NE)
C). The electrolytic solution was adjusted to a 1% NaCl aqueous solution using primary sodium chloride. As a measuring method, 0.1 to 5 ml of a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant to 50 to 100 ml of the electrolytic solution, and 1 to 10 mg of a sample is added. This is subjected to a dispersion process for one minute by an ultrasonic disperser. In a separate beaker, 100 to 200 ml of the aqueous electrolytic solution is added, and the sample dispersion liquid is added thereto at a predetermined concentration, and a 100 μm aperture is used as an aperture by the Coulter Counter TA-II. The particle size distribution of 30,000 particles of ４０40 μm is measured, the volume distribution and the number distribution of the particles of 2 to 40 μm are calculated, and the weight-based volume average particle diameter (D4: the median value of each channel is calculated from the volume distribution) Channel representative value).

[0032]

EXAMPLES The present invention will be described more specifically with reference to the following examples, but the present invention is not limited to these examples. Further, in the embodiment, a two-component black toner is exemplified, but it is also possible to use a full-color toner. Table 1 shows the detailed results.

(Example 1) Polyester resin A (chloroform-insoluble content 3%) 20 parts by weight Styrene acrylic resin 80 parts by weight Polyethylene wax 7 parts by weight Carbon black (# 44: manufactured by Mitsubishi Kasei Corporation) 10 parts by weight Metal of salicylic acid derivative 1 part by weight of salt The mixture of the above composition is sufficiently stirred and mixed in a Henschel mixer, and then heated and melted at a temperature of 140 ° C. for about 30 minutes by a roll mill, cooled to room temperature, and the obtained kneaded material is jet-milled or mechanically pulverized. And a pneumatic classifier to obtain a toner base. Hydrophobic silica 0.5 was added to the obtained toner matrix.
wt% was added and mixed to obtain a final toner. At this time, the average volumetric particle diameter of the toner was 6.5 μm, and the content of 5 μm or less was 85%. The chloroform-insoluble content of the toner was 0%.

3 g of the toner thus obtained was put into a tableting die and pressed under a load of 6 tons for 1 minute to give a diameter of 40 tons.
mm plate-like toner pellets were prepared. The pellets were analyzed using the automatic friction and wear analyzer (DF manufactured by Kyowa Interface Science Co., Ltd.)
(PM-SS type), the static friction coefficient was measured under the conditions of a point contact method using a stainless steel ball as a contact, a load of 50 g and a stroke of 10 mm, and the value of the toner surface friction coefficient was 0.23.

The carrier is not coated with a resin,
3. The above toner and toner concentration using a ferrite carrier.
It was mixed at 0% by weight and used as a two-component developer.

[Evaluation Items] (Evaluation of Fixing Property) Copier MF- manufactured by Ricoh Co., Ltd. using a Teflon (registered trademark) roller as a fixing roller.
Ricoh type 6200 paper was set in this apparatus using a modified 200 fixing unit, and a copying test was performed.
A copy image having an image density of 1.2 with a Macbeth densitometer was obtained, and the copy image with the fixing temperature changed was rubbed 10 times with a clock meter equipped with an eraser,
The image density before and after that was measured, and the fixing rate was determined by the following equation. (Image density 10 times after sand eraser) / (Previous image density)
× 100 = Fixing rate (%) The temperature at which the fixing rate is 70% or more is defined as a fixing lower limit temperature which is a measure of low-temperature fixing property. The minimum fixing temperature of the conventional low-temperature fixing toner is about 140 to 150 ° C. The evaluation condition of the low-temperature fixing was that the linear speed of the paper feed was 120 to 150 mm /
sec, surface pressure 1.2 kgf / cm ² , nip width 3 mm,
Evaluation condition of hot offset is linear velocity of paper feed 50m
m / sec, surface pressure 2.0 kgf / cm ² , nip width 4.
It was set to 5 mm. The cold offset occurrence temperature and the hot offset occurrence temperature were determined as follows. (Low-temperature fixability) good ◎: less than 130 ° C., ：: 130 to 140 ° C., □: 140 to 150 ° C., Δ: 150 to 160 ° C., ×: 160 ° C. or more, poor. (Hot offset property) Good ：: 201 ° C. or more, ：: 200 to 191 ° C., □: 190 to 181 ° C., Δ: 180 to 171 ° C., ×: 170 ° C. or less

(Evaluation of heat resistance storage stability)
After placing the sample in a 0 ml glass bottle and tapping the glass bottle approximately 50 times to solidify the sample, the sample is left in a constant temperature bath at 50 ° C. for 24 hours, and then the penetration is determined using a penetration tester as follows. Was.

A copying machine imagiio2730 manufactured by Ricoh Co., Ltd. was set, and a paper-passing test was performed.
And the spent ratio.

(Filming) Continuous 100,000 sheets (print rate 6
%) Copies were made and after 100,000 copies, it was confirmed whether filming had occurred on the photoreceptor. At the same time, a halftone image was output, and the presence or absence of a white band was evaluated.
The evaluation of the filming on the photoreceptor was visually classified into five ranks, and the better grade was ranked 5 and the worse grade was 1. Regarding the halftone white band, it was evaluated as ○ when it did not occur, Δ when it occurred but it occurred at an allowable level, and X when it occurred at the NG level.

(Image Stability) Continuous 100,000 Sheets (Print Rate 6
%) Image density after copying 100,000 sheets, fine line reproducibility,
The soil was examined and judged comprehensively. ◎: particularly excellent, ：: excellent, Δ: slightly poor, ×: extremely poor.

(Spent ratio) The toner was removed from the developer after the copy test of 300,000 sheets by a blow-off method, the remaining carrier weight W1 was put in toluene, and the fused material was dissolved, washed and dried. Was determined from the weight W2 and evaluated. Spent ratio (wt%) = [(W1-W2) / W1] ×
100

Comparative Example 1 A toner similar to that of Example 1 was obtained and evaluated, except that the wax of Example 1 was changed to 15 parts by weight of low molecular weight polypropylene (Viscol 660P: manufactured by Sanyo Chemical Industries, Ltd.). At this time, the average volumetric particle diameter of the toner was 6.5 μm, and the content of 5 μm or less was 85%. The chloroform-insoluble content of the toner was 0%. The value of the toner surface friction coefficient at this time is 0.1
It was 8. As a carrier, a ferrite carrier not coated with a resin is used, and the toner and the toner concentration are 4.
It was mixed at 0% by weight and used as a two-component developer.

Comparative Example 2 Evaluation was performed in the same manner as in Example 1 except that the melting temperature during kneading the toner with a roll mill was changed to 180 ° C. At this time, the average volumetric particle diameter of the toner was 6.5 μm, and the content of 5 μm or less was 87%. The chloroform-insoluble content of the toner was 0%. The toner surface friction coefficient at this time was 0.16. A ferrite carrier not coated with a resin was used as a carrier. The carrier was mixed with the toner at a toner concentration of 4.0% by weight and used as a two-component developer.

(Example 2) A toner similar to that of Example 1 was obtained except that the wax of Example 1 was changed to 7 parts by weight of defatty acid-type carnauba wax. At this time, the average volume particle diameter of the toner is 6.5 μm, and the content of 5 μm or less is 85%.
Met. The chloroform-insoluble content of the toner was 0%. Further, the value of the toner surface friction coefficient at this time was 0.28. A ferrite carrier not coated with a resin was used as a carrier. The carrier was mixed with the toner at a toner concentration of 4.0% by weight and used as a two-component developer.

Example 3 A toner was prepared in the same manner as in Example 1 except that the amount of the wax used in Example 2 was changed to 4.5 parts by weight of the free fatty acid type carnauba wax. At this time, the average volume particle size of the toner is 6.5 μm.
The content was 5% or less, and the content was 80%. The chloroform-insoluble content of the toner was 0%. The value of the coefficient of friction at this time was 0.3. A ferrite carrier not coated with a resin was used as a carrier. The carrier was mixed with the toner at a toner concentration of 4.0% by weight and used as a two-component developer.

(Example 4) Polyester resin B 20 parts by weight (chloroform-insoluble content 25%) Styrene acrylic resin 80 parts by weight Free fatty acid type carnauba wax 4.5 parts by weight Carbon black 10 parts by weight (# 44: Mitsubishi Chemical) 1 part by weight of a metal salt of a salicylic acid derivative A mixture having the above composition was prepared in the same manner as in Example 1 to obtain a toner. At this time, the average volumetric particle diameter of the toner is 6.5 μm.
m, the content was 5% or less, and the content was 80%. The chloroform-insoluble content of the toner was 21%. Further, the value of the toner surface friction coefficient at this time was 0.3. A ferrite carrier not coated with a resin was used as a carrier. The carrier was mixed with the toner at a toner concentration of 4.0% by weight and used as a two-component developer.

Example 5 Kneading was carried out using the same raw material formulation as in Example 4, and then the pulverizing step and the classifying step were adjusted to obtain a toner base. 0.5 wt% of hydrophobic silica was added to and mixed with the obtained toner base to obtain a final toner. At this time, the average volume particle size of the toner was 6.5 μm, and the content of 5 μm or less was 65%. Further, the chloroform-insoluble content of the toner was 22%. Further, the value of the toner surface friction coefficient at this time was 0.32. A ferrite carrier not coated with a resin was used as a carrier. The carrier was mixed with the toner at a toner concentration of 4.0% by weight and used as a two-component developer.

(Example 6) 100 parts by weight of polyester resin B (chloroform insoluble content: 25%) 4.5 parts by weight of free fatty acid-type carnauba wax 10 parts by weight of carbon black (# 44: manufactured by Mitsubishi Kasei Co., Ltd.) Metal salt 1 part by weight A mixture having the above composition was prepared in the same manner as in Example 1 to obtain a toner. At this time, the average volumetric particle diameter of the toner is 6.5 μm.
m, the content was 5% or less, and the content was 63%. The chloroform-insoluble content of the toner was 21%. Further, the value of the toner surface friction coefficient at this time was 0.32. A ferrite carrier not coated with a resin was used as a carrier. The carrier was mixed with the toner at a toner concentration of 4.0% by weight and used as a two-component developer.

Example 7 The same toner as in Example 6 was used, and the carrier used was a magnetite particle having an average particle diameter of 50 μm coated with a silicone resin (film thickness: 0.5 μm). It was mixed at 4.0% by weight and used as a two-component developer.

[0050]

[Table 1]

[0051]

As described above, according to the present invention, high heat resistance is ensured while securing low-temperature fixability even in a use environment in which the stirring time for development is long and the heat stress to the developer is large due to the fixing at a low surface pressure. An image forming toner capable of stably obtaining a good image can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a fixing device used in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixing roller 2 Pressure roller 3, 6 Metal cylinder 4, 7 Offset prevention layer 5, 8 Heating lamp

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 15/20 107 G03G 15/08 507L (72) Inventor Fumihiro Sasaki 1-3-3 Nakamagome, Ota-ku, Tokyo No. 6 Inside Ricoh Company (72) Inventor Hiroto Higuchi 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Inside Ricoh Company (72) 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Inside Ricoh Company (72) Inventor Yasushi Furuichi 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh F-term (reference) 2H005 AA01 AA06 BA06 CA08 CA12 CA14 EA05 EA07 EA10 2H033 AA02 AA32 BA58 BB03 BB06 BB13 BB29 BB34 2H077 AB00 DA01 DB14 DB25 EA03

Claims (9)

[Claims] 1. A toner mainly comprising at least a binder resin, a wax, and a colorant, wherein a surface friction coefficient of the toner when pressed into a plate shape is 0.2 or more. An electrostatic image developing toner. 2. The electrostatic image developing toner according to claim 1, wherein the wax dispersed in the toner is carnauba wax, rice wax and / or ester wax. 3. The content of wax dispersed in the toner is:
The electrostatic image developing toner according to claim 1, wherein the amount is 5% by weight or less based on the binder resin in the toner. 4. The toner according to claim 1, wherein the chloroform-insoluble content is 2 to 45.
The toner for developing an electrostatic image according to claim 1, wherein 5. The toner has an average volume particle size of 5 to 10 μm.
5. The toner according to claim 1, wherein the content of the toner having a particle size of 5 [mu] m or less is 60 to 80% by number. 6. The toner for developing an electrostatic charge image according to claim 1, further comprising 50% by weight or more of a polyester resin as a resin component. 7. A two-component developer comprising the toner according to claim 1 and a carrier. 8. The two-component developer according to claim 7, wherein a carrier whose surface is coated with a silicone resin is used. 9. A two-component developer comprising a toner containing at least a binder resin, a wax and a colorant and a carrier, and having a surface pressure (roller load / contact area) of 1.5 during fixing.
An electrophotographic image forming apparatus using an oilless fixing of × 10 ⁵ Pa or less, and a system speed of 150 to 760 mm / s
At the speed of ec, the developer stirring time of one copy per original is 4 seconds or more, and the developer stirring time of one copy per original is 2 times of the developer stirring time per continuous copy. Claims 1 to 8
8. An image forming method using the toner for developing an electrostatic image or the two-component developer according to any one of 8.