JP2003043785A - Developing method and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing method which does not give rise to staining of an electrostatic charging roll in spite of an increase in the number of printing sheets and hardly gives rise to the fogging of forms even under such a severe environment like a high temperature and high humidity and a low temperature and low humidity and an image forming method. SOLUTION: The developing method of forming an electrostatic latent image on the surface of a latent image holder uniformly electrostatically charged by an electrostatic charging roll and developing this electrostatic latent image to a toner image by a toner, the image forming method of transferring the toner image developed by this method to a transfer member, then fixing the image and the color image forming method, in which the electrostatic charging roll formed by coating a metallic core material with a rubber layer of 0.5 to 10 μm in surface roughness and further coating this rubber layer with a polyurethane resin of 30 to 80 deg.C in glass transition temperature and toner of 0.1 to 100 ppm in total of the contents of boron and phosphorus in the toner is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing method and an image forming method by electrophotography, and more particularly, a developing method and a developing method which do not cause paper fogging even under severe environments such as high temperature and high humidity and low temperature and low humidity. The present invention relates to an image forming method.

[0002]

2. Description of the Related Art An image forming method utilizing an electrophotographic system such as an electrophotographic printer is a charging process in which the surface of a photosensitive drum as a latent image carrier is uniformly and evenly charged by a charging device. Exposure step of forming an electrostatic latent image on the surface of the photoconductor by a latent image forming device such as a laser irradiation device, a developing step of developing the electrostatic latent image using toner by a developing device, and a developing device by a transfer device It has a transfer step of transferring the transferred toner image to a transfer material and a fixing step of fixing the transferred toner image.

Conventionally, in the charging step of such an image forming method, charging is generally performed by corona discharge. However, the harmful potential such as ozone is generated, the humidity changes the charging potential of the photosensitive drum, and the image characteristics are changed. Had problems such as adversely affecting. In order to solve the problem, a charging method using a charging roll has been proposed.

As such a charging roll, for example, styrene-butadiene rubber, styrene-acrylonitrile rubber, natural rubber and other rubbers having high electric resistance, carbon black, carbon fibers, metal oxides, and metals are provided on a core metal. A roll provided with a coating layer made of a composition containing a conductive substance such as powder is known. However, in these charging rolls, in order to control the charging property of the toner,
The electrical resistance of the charging roll must be reduced to an appropriate range, and therefore a relatively large amount of conductive material must be dispersed. However, in a charging roll containing a large amount of a conductive substance, there is a problem in that the hardness is high, the contact with the photosensitive drum is insufficient, and the charging is not uniform.

Therefore, a low-hardness charging roll has been proposed in which a composition of ethylene / propylene / diene copolymer (EPDM) and a conductive substance is impregnated with process oil.
The impregnated process oil was released to contaminate the photoconductor, causing unevenness in the visible image. In order to solve this problem, it was also proposed to wind a nylon sheet around the surface of this roll, but with a thin nylon sheet, it is not possible to sufficiently prevent photoreceptor contamination, making the nylon sheet thicker,
Other than nylon sheets, it is also used in multiple layers.
Therefore, there arises a problem that the chargeability of the toner cannot be controlled.

Further, the charging roller having a low hardness has a problem that the toner remaining on the photosensitive drum tends to adhere to the charging roller when mounted on a cleanerless image forming apparatus.
That is, in the cleanerless method, the photosensitive drum is charged by the charging roll in the state where the untransferred residual toner is present on the photosensitive drum, so that the toner is easily attached to the charging roll. If the toner adheres to the charging roll, the toner adheres to the charging roll more severely as the number of printed sheets increases, which makes it impossible to uniformly charge the photosensitive drum, which causes fog and streaks.

In order to solve the problem, a charging roll having a non-adhesive layer made of a fluorine-containing cross-linked copolymer on a rubber layer having a medium electric resistance and a low hardness, such as epichlorohydrin rubber. (JP-A-6-266206)
Also, a charging roll (Japanese Patent Laid-Open No. 7-49605) provided with a surface layer of a fluororesin, a polyamide resin, an acrylic resin or the like which may contain various inorganic fillers or conductive particles has been proposed, Each of them had a problem that the hardness was high and the charging was not uniform.

In order to reduce the adhesion of the toner to the charging roll, it is necessary to reduce the tackiness of the roll surface and keep the friction coefficient small. In order to impart good chargeability to the photosensitive drum, it is necessary to increase the contact area between the charging roll and the photosensitive drum, and for that purpose, it is required to reduce the surface hardness of the charging roll. On the other hand, in order to apply a bias voltage to the charging roll, the electric resistance of the charging roll must be lowered. The charging roll is deformed by contact with the photosensitive drum, but must not be permanently deformed by it. As described above, many characteristics are required for the charging roll. Further, in an image forming apparatus having a structure in which the charging roll and the photosensitive drum are in contact with each other, they are always in contact with each other. Therefore, it is necessary to prevent the photosensitive drum from being contaminated by the charging roll. Particularly, as organic photoconductors (OPC photoconductors), which are easily polluted, have been used with the downsizing of devices, prevention of pollution has become a more important issue.

[0009]

The applicant of the present invention has proposed a metal core material (core metal) as a charging roll satisfying the above-mentioned requirements.
There is proposed a charging roll in which the surface of the rubber layer is coated with a rubber layer, the surface of the rubber layer is made to have a specific surface roughness, and then a polyurethane resin having a specific glass transition temperature is coated thereon (JP-A-9-160354). Gazette). However, it has been found that when the number of printed sheets increases, stains on the charging roll occur, and paper fogging cannot be suppressed under severe environments such as high temperature and high humidity and low temperature and low humidity. Therefore, it is an object of the present invention to provide a developing method and an image forming method that do not cause stains on the charging roll even when the number of printed sheets increases and that does not cause paper fog even in a severe environment such as high temperature and high humidity and low temperature and low humidity. is there.

[0010]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to achieve the above object, and as a result, use a specific charging roll as a charging roll constituting an image forming apparatus, and use a specific toner. By doing so, it was found that the above object can be achieved, and the present invention has been completed based on this finding. Thus, according to the present invention, an electrostatic latent image is formed on the surface of the latent image carrier uniformly charged by the charging roll,
A developing method for developing this electrostatic latent image into a toner image with toner, in which a charging roll covers a metal core material with a rubber layer having a surface roughness of 0.5 to 10 μm, and the rubber layer is further covered. A developing method comprising a coating layer of a polyurethane resin having a glass transition temperature of 30 to 80 ° C., and the total content of boron or phosphorus in the toner is 0.1 to 100 ppm, and a developing method by this method. An image forming method and a color image forming method are provided in which the toner image thus formed is transferred to a transfer material and then fixed.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In the developing method of the present invention, an electrostatic latent image is formed on the surface of a latent image carrier uniformly charged by a charging roll, and this electrostatic latent image is developed from a supply roll. In developing a corresponding toner image with the toner on the developing roll which is supplied to the roll and whose layer thickness is adjusted by the layer thickness regulating blade, the metal core material has a surface roughness of 0.5 to 10 μm, preferably 1 to A charging roll is used which is covered with a rubber layer having a thickness of 8 μm, and which is further covered with a polyurethane resin coating layer having a glass transition temperature of 30 to 80 ° C. In the present invention, the surface roughness of the charging roll means the surface roughness in the axial direction.

If the surface roughness of the rubber layer is larger than 10 μm, the surface roughness of the coated surface cannot be sufficiently reduced even if the surface is covered with the polyurethane resin, and as a result, the OPC photoreceptor is significantly contaminated. The toner remaining on the photosensitive drum adheres to the charging roll, causing fog on the printing paper. If the surface roughness is less than 0.5 μm, the manufacturing cost of the roll becomes high and it is difficult to use it industrially.

The surface roughness is measured according to JIS B-0601.
The surface of the roll is traced in the measuring direction with a stylus and the movement thereof is recorded to express the irregular shape of the surface as a surface roughness curve. Select 5 points from the highest and 5 points from the low of this curve, average each of them, and calculate the difference between the obtained average values as the surface roughness (Rz).
And

As means for imparting the surface roughness of the above range to the surface of the charging roll, means for polishing the outer peripheral surface of the rubber elastic body with a cylindrical cutting machine or the like can be used. Polishing is first performed with a coarse cutting file or grindstone, and finally with a fine file or grinding wheel or wet polishing.

The glass transition temperature (T
g) needs to be 30 to 80 ° C. If a polyurethane resin having a glass transition temperature outside this range is used, the coefficient of friction of the polyurethane resin coating is not sufficiently reduced and fogging occurs due to toner adhesion, which is not practical. The tensile strength of the polyurethane resin coating is 2
000 g / mm2 or more is preferable, 3000 g / mm2
The above is more preferable. Tensile strength is determined by punching a sheet-shaped polyurethane resin with a dumbbell to make a sample, and using a tensile tester to measure it at a constant speed (for example,
It can be measured by pulling at (500 mm / min).

The polyurethane resin which can be preferably used in the present invention is a reaction product of a polyfunctional isocyanate compound and a polyether polyol or a polyester polyol. The polyurethane resin has a molecular weight of usually 100,000 to 500,000, preferably 200,000 to 300,000, and may have a hydrophilic functional group such as a hydroxyl group or a carboxyl group in the molecular chain. The molecular weight referred to in the present invention is a weight average molecular weight of a tetrahydrofuran-soluble component, and after dissolving a predetermined amount of a polyurethane resin in tetrahydrofuran,
A sample can be prepared by filtering with a membrane filter and measured as a polystyrene reduced molecular weight by gel permeation chromatography.

Polyfunctional isocyanate compound (that is,
As a compound having two or more isocyanate groups),
Aromatic isocyanates such as triphenylmethane triisocyanate, 4,4-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, tolylene diisocyanate, tetramethyl xylene diisocyanate, xylene diisocyanate; dicyclohexane diisocyanate, dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, isophorone Aliphatic isocyanate such as diisocyanate; and the like.

Examples of the polyether polyol include polyoxytetramethylene glycol, polyethylene glycol, polypropylene glycol and the like. The polyester polyol is one having a hydroxyl group at the molecular end obtained by reacting a polyvalent carboxylic acid and a polyol (including a polyether polyol), and a polycarbonate diol is exemplified. Examples of the polycarboxylic acid include adipic acid, phthalic acid, sebacic acid, and dimer acid. Examples of the polyol include ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, 1,3-butanediol, hexanetriol, trimethylolpropane, glycerin, pentaerythritol, sorbitol, and glycol dicarboxylate.

As the polyurethane resin, one dissolved in an organic solvent may be used, but in addition to the problem of environmental pollution due to volatilization of the organic solvent, the evaporation rate of the organic solvent is high, so that the surface roughness of the polyurethane resin coating layer is It is difficult to reduce the size, and since it is easy to cause inconveniences such as swelling the rubber layer and extracting a compounding agent from the rubber layer, it is used as a self-emulsifying type or forced emulsifying type polyurethane resin aqueous dispersion. It is preferable. The self-emulsifying type or forced emulsifying type aqueous dispersion of polyurethane resin may be synthesized and used, but commercially available products such as "Superflex" series manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd. may be used. The polyurethane resin may further contain a functional group or a reactive group, whereby various film forming conditions such as drying, heat curing, and ultraviolet curing can be selected.

The thickness of the polyurethane resin coating is usually 1
It is about 0 to 50 μm. The surface roughness of the charging roll on which the polyurethane resin coating is formed is usually 0.01 to 5 μm.
m, preferably 0.05 to 2 μm, and the coefficient of friction is
Usually, it is 0.5 or less, preferably 0.3 or less.

The friction coefficient in the present invention is a coefficient obtained by the Euler belt type friction coefficient measuring method shown in FIG. The friction coefficient is measured as follows. That is, first, the measurement paper 40 is cut into a certain size (for example, 2 cm × 20 cm), a weight 42 having a predetermined weight (for example, 50 g) is attached to one end, and a tension gauge 44 is attached to the other end. One end with the weight attached is brought into contact with and hangs around the developing roll to be measured, the angle of the measurement paper is set to 90 degrees, and the end with the weight attached is fixed speed (about 100 ±
20 mm / min). Read the value (tension) when the measurement paper starts moving on the roll surface and the scale of the tension gauge is stable. The friction coefficient μs is calculated from the measured value (tension) F read by a tension gauge and the weight weight W by the following mathematical formula. μs = 2 / π × Ln (F / W)

If the rubber layer of the charging roll is coated with polyurethane resin, the friction coefficient of the contact portion between the roll surface and the photosensitive drum becomes low, and the toner remaining on the photoconductor does not easily adhere to the charging roll. The charge is also uniform. As a result, the toner easily adheres uniformly, and uneven printing, blurring, fog, and the like do not occur.

The charging roll used in the developing method of the present invention has a volume resistivity (a) of preferably 1 × 1 when measured in an L / L environment at a temperature of 10 ° C. and a humidity of 20%.
05 to 1 × 10 10 Ω · cm, more preferably 1 × 10
It is 6 to 1 × 10 9 Ω · cm. Further, when measured in an H / H environment at a temperature of 35 ° C. and a humidity of 80%, the volume specific resistance value (b) is smaller than the volume specific resistance value (a) measured in the L / L environment. In the charging roll used in the developing method of the present invention, the ratio (a / b) of them is preferably 10 or less, so that the environmental dependence of the electric resistance is small. In order to adjust the volume specific resistance value of the charging roll within an appropriate range, 0.1 to 100 parts by weight of the rubber composition is used.
It is preferable to add about 5 parts by weight of a conductive substance.

Since the charging roll coated with the polyurethane resin used in the present invention can be brought into close contact with the photosensitive drum to give a sufficient charging property, the hardness (JIS A) is 30.
It is preferable that it is appropriately small as about 40. Further, the charging roll used in the present invention has a small friction coefficient of usually 0.5 or less, can rotate smoothly in contact with the photosensitive drum, and when applied to a cleanerless image forming apparatus. However, there is no toner adhesion and fog does not occur.

As the material of the rubber layer coating the surface of the metal core material (core metal), various rubbers or rubber compositions (blends of two or more kinds of rubbers) generally used in the field of charging rolls are used. Can be mentioned. Specific examples of such rubber include epihalohydrin rubber, urethane rubber, silicon rubber, polybutadiene, acrylonitrile-butadiene copolymer rubber, and styrene-butadiene copolymer rubber. Among these, a rubber composition containing an epihalohydrin rubber and an acrylonitrile-butadiene copolymer rubber is suitable.

More specifically, as a preferred rubber component,
A rubber composition containing 40 to 90% by weight of epihalohydrin copolymer rubber (A), 5 to 40% by weight of unsaturated rubber (B), and 5 to 20% by weight of liquid unsaturated rubber (C) can be mentioned. . Epihalohydrin copolymer rubber (A)
Is preferably 50 to 90% by weight, more preferably 55 to 85% by weight. If this percentage is high,
The hardness and friction coefficient may increase, and further, problems such as contamination of the photoconductor and adhesion of toner may occur.

As described above, when the rubber layer is formed by using the rubber composition in which the epihalohydrin copolymer rubber, the unsaturated rubber which is solid at room temperature and the liquid unsaturated rubber which is liquid at room temperature are blended in a specific ratio, the electroconductivity is improved. It is preferable that a roll having a reasonably low electric resistance, excellent environmental stability of electric resistance, moderately low hardness and a small friction coefficient can be obtained without containing a large amount of the substance.

The epihalohydrin copolymer rubber (A) is
A copolymer rubber obtained by copolymerizing a monomer mixture containing epihalohydrin as an essential monomer. Examples of epihalohydrin include epichlorohydrin,
Examples include epibromohydrin and epifluorohydrin. Among these, in terms of availability and price,
Epichlorohydrin is preferred. As the monomer copolymerizable with epihalohydrin, alkylene oxide and ethylenically unsaturated epoxide are preferable.

The copolymerization ratio of epihalohydrin in the epihalohydrin copolymer rubber is usually 28 to 70 mol%,
Preferably 30-65 mol%, more preferably 35-6
It is 0 mol%. If this ratio is large, the electric resistance may be high, and if this ratio is small, the hygroscopicity may be high, or the environmental resistance of the electric resistance may be high, so both are not preferable.

Examples of alkylene oxides include:
Examples thereof include ethylene oxide, propylene oxide, butylene oxide, and these can be used alone or in combination of two or more kinds. When used alone, ethylene oxide (EO) is preferred. When used in combination, ethylene oxide (EO) and propylene oxide (PO)
It is preferable to use and together. The copolymerization ratio of the alkylene oxide in the epihalohydrin copolymer rubber is usually 28 to 70 mol%, preferably 35 to 65 mol%,
More preferably, it is 40 to 60 mol%. If this ratio increases, the hygroscopicity may increase, or the environmental resistance of the electrical resistance may increase, and if this ratio decreases, the electrical resistance may increase, so
Neither is preferable.

Examples of the ethylenically unsaturated epoxide include allyl glycidyl ether, glycidyl methacrylate, glycidyl acrylate and butadiene monooxide. By copolymerizing an ethylenically unsaturated epoxide, vulcanization by a sulfur vulcanization system (sulfur or a sulfur donor) or a peroxide becomes possible, and thermal softening deterioration resistance and dynamic ozone resistance are improved. The copolymerization ratio of the ethylenically unsaturated epoxide in the epihalohydrin copolymer rubber is usually 2 to 15 mol%, preferably 3 to 10 mol%. If this ratio is high, curing deterioration due to heat may occur, rubber elasticity may be lost, and brittleness may easily occur.
If this ratio is small, vulcanization and curing become difficult, and it may not be possible to obtain a smooth rubber sheet.

The unsaturated rubber (B) referred to in the present invention is an unsaturated rubber which is solid at room temperature. As the unsaturated rubber, for example, acrylonitrile-butadiene copolymer rubber (N
BR), styrene-butadiene copolymer rubber (SB
R), polybutadiene rubber (BR), ethylene / propylene / diene copolymer rubber (EPDM), chloroprene rubber, acrylonitrile / isoprene copolymer rubber, acrylonitrile / butadiene / isoprene copolymer rubber (NBIR), urethane rubber, and Partial hydrogenation products of these rubbers and the like can be mentioned. Among these, NBR
Also, partially hydrogenated NBR is preferable because it has good compatibility with the epihalohydrin copolymer rubber. The proportion of unsaturated rubber (B) is preferably 5 to 35% by weight, more preferably 5 to 3%.
It is 0% by weight. If this ratio is large, it may be difficult to obtain an appropriately low electric resistance, and conversely, if it is small, the workability may be reduced, or the hardness and friction coefficient may be increased.

The liquid unsaturated rubber referred to in the present invention is an unsaturated rubber which is in a liquid state at room temperature. Examples of such liquid unsaturated rubber include liquid polybutadiene, liquid NBR,
Liquid chloroprene and the like can be mentioned. Among these,
Liquid NBR is preferable because it has good compatibility with the epihalohydrin copolymer rubber and NBR and partially hydrogenated NBR. The proportion of liquid unsaturated rubber (C) is preferably 5 to 15% by weight.
Is. If this ratio is high, the friction coefficient will be high, and the toner may adhere to the charging roll. Conversely, if it is low, the hardness will be high and the contact with the photosensitive drum will be insufficient, resulting in uneven charging. May be.

In producing the charging roll used in the present invention, in order to coat the surface of the metal core material with the rubber layer, a roll-shaped base material such as a metal rotating shaft is used as a core metal in the roll mold. Then, the rubber composition containing a vulcanizing agent and the like is placed therein, and the rubber composition is shaped around the core metal in a roll shape, and then heated to be vulcanized. As the vulcanizing agent, a sulfur-based vulcanizing agent or peroxide is usually used. Metal oxides can be used, but they are not preferable because they may contaminate the photosensitive drum. The amount of the vulcanizing agent is 100 parts by weight of the rubber composition,
Usually, it is used in a proportion of 0.1 to 5 parts by weight, preferably 0.2 to 3 parts by weight. In the charging roll used in the developing method of the present invention, the rubber composition used as the rubber layer coating the surface of the metal core material, if necessary, a reinforcing agent,
A rubber additive such as a filler or an anti-aging agent can be appropriately blended. Vulcanization conditions such as vulcanization temperature and vulcanization time can be appropriately determined according to the type of rubber component used.
For example, when the rubber component is an epihalohydrin copolymer rubber or a rubber composition containing the epihalohydrin copolymer rubber, it is usually heated at 100 to 250 ° C. for about 10 to 60 minutes.

As a method for coating the polyurethane resin on the rubber layer, a polyurethane resin water dispersion or the like is used.
Methods such as brush coating, spray coating, and dipping can be adopted. After coating the aqueous dispersion on the rubber layer, a dry film is formed by a method such as drying, heating, or ultraviolet irradiation.

The toner used in the present invention contains boron or phosphorus, preferably boron. The content of these is 0.1 to 100 ppm, preferably 0.2 to 50 pp
m, more preferably 0.5 to 10 ppm. When both boron and phosphorus are contained, the total amount is within the above range. When the content of boron or phosphorus is low, the cleaning failure on the photoconductor is likely to occur and the image quality is apt to deteriorate. On the contrary, when the content is high, fog occurs when the temperature or humidity changes. The image quality will deteriorate.

As a method of incorporating boron or phosphorus into the toner, i) a boron or phosphorus compound is added at the time of melting and kneading the binder resin, ii) polymerization is performed in the presence of the boron or phosphorus compound, and iii) pulverization , Post-addition to the toner produced by polymerization, association and the like. Of these, it is preferable to apply the method of polymerization in the presence of the boron or phosphorus compound of ii) because stability during polymerization is improved. The boron or phosphorus content is a value measured by the following method. That is, about 5 g of the precisely weighed toner is put in a 100 ml Erlenmeyer flask, 50 ml of ion-exchanged water is added, the weight thereof is measured, and then shaken to disperse the toner. Next, the container is heated with an electric heater or a gas burner and boiled for 10 minutes. In addition, the amount of deionized water that has been boiled in advance is reduced by boiling and added to an Erlenmeyer flask. The boiled toner dispersion is filtered through a filter paper, and boron or phosphorus dissolved in the filtrate is quantified using ion chromatography, and this measured value is used as the content in the toner.

The toner contains boron or phosphorus in an amount of 0.1 to 10
Although the reason why the above-mentioned effect appears by containing 0 ppm is not clear, the following reasons are considered. Usually, the toner is highly charged due to friction, and the toner is accumulated in the developing device. Therefore, when the number of printed sheets increases, toner scattering or fog (so-called deterioration of durability) occurs. Further, due to the high electric charge, the toner is adsorbed by the layer thickness regulating blade, and filming occurs. Therefore, in order to control the charging, a conductive material is used for a developing roll, a layer thickness regulating blade, or the like to discharge the charge. However, with the normal toner, only the electric charge of the portion in contact with the developing roll or the layer thickness regulating blade is released. On the other hand, when these elements are present in the toner, electric charges are released through the surface of the toner, so that it becomes easy to control charging, and toner scattering, fogging, and filming are suppressed. It is speculated that it can be done.

The volume average particle diameter (dv) of the toner used in the present invention is not particularly limited, but is usually 2 to 10 μm, preferably 2 to 9 μm, more preferably 3 to 8 μm. Also, volume average particle diameter (dv) / number average particle diameter (d
Although p) is not particularly limited, it is usually 1.7 or less, preferably 1.5 or less, more preferably 1.3 or less. 2 to
The toner having a number average particle diameter of 4 μm is preferably 4 to 8% by number. If it is less than this amount, the resolution may be lowered, and if it is more than that, the fluidity may be lowered. Moreover, the sphericity (Sc / Sr) of the value obtained by dividing the area (Sc) of the circle having the absolute maximum length of the particle as the diameter by the substantial projected area (Sr) of the particle has a sphericity of 1 to 1.
It is preferably a substantially spherical toner having a particle size of 3, preferably 1 to 1.2.

A preferable toner used in the present invention is a volume resistivity value (log (Ω · cm)) measured by a dielectric loss measuring instrument.
Is usually 10 to 13, preferably 10.5-12.5. If the volume resistivity value is small, fog may occur, and if it is large, toner scattering, fog,
Filming or poor cleaning may occur. The preferred toner used in the present invention has a softening temperature (hereinafter sometimes referred to as Ts) by a flow tester of usually 50 to 80 ° C., preferably 60 to 70.
C., and the flow starting temperature (hereinafter sometimes referred to as “Tfb”) is usually 90 to 150 ° C., preferably 100.
~ 130 ° C. If the softening temperature is low, the storability may decrease, and conversely, if the softening temperature is high, the fixability may decrease.
If the flow start temperature is low, the hot offset resistance may decrease, and conversely if the flow start temperature is high, the fixability may decrease.
The glass transition temperature measured by a differential scanning calorimeter (hereinafter, also referred to as "DSC") is usually 20 to 80 ° C, preferably 40 to 70 ° C. If the glass transition temperature is low, the storability may be lowered, and conversely, if it is high, the fixability may be lowered.

The toner used in the present invention may be so-called core-shell type (also referred to as capsule type) particles obtained by combining two different polymers inside (core layer) and outside (shell layer) of the particles. it can. In core-shell type toner, by forming a shell (shell layer) on the surface of the low softening point substance inside (core layer) with a substance having a higher softening point, lowering the fixing temperature and preventing aggregation during storage This is preferable because it can be balanced with As a method for obtaining the core-shell type toner, a method such as a spray dry method, an interfacial reaction method, an in situ polymerization method or a phase separation method can be adopted. In particular, the in situ polymerization method and the phase separation method are preferable because they have high production efficiency. Further, the core particles of the core-shell type toner may be those obtained by a pulverizing method or those obtained by a polymerization method, an association method or a phase inversion emulsification method.

The weight ratio of the core layer and the shell layer of the core-shell type toner is not particularly limited, but is usually 80/20 to 9
Used at 9.9 / 0.1. If the ratio of the shell layer is less than the above ratio, the storability is deteriorated, and conversely, if it is more than the above ratio, fixing at low temperature may be difficult.

The average thickness of the shell layer of the core-shell type toner is usually 0.001 to 1 μm, preferably 0.003 to.
The thickness is 0.5 μm, more preferably 0.005 to 0.2 μm. If the thickness is large, the fixability may be lowered, and if it is small, the storage stability may be lowered. The core particles forming the core-shell type toner do not need to be covered with the shell layer on all the surfaces. The core particle diameter and the thickness of the shell layer of the core-shell type toner can be measured by directly measuring the size and shell thickness of particles randomly selected from the observation photograph, when the particles can be observed by an electron microscope. When it is difficult to observe the core layer and the shell layer with a microscope, it can be calculated from the particle size of the core particles and the amount of the polymerizable monomer forming the shell layer used in the production of the toner particles.

The toner used in the present invention contains a binder resin, a colorant and a charge control agent, and may further contain other additives such as a releasing agent and a magnetic material, if necessary.

As the binder resin, a resin that has been widely used in toners from the past can be used. For example, polystyrene, a polymer of styrene such as polyvinyltoluene and its substitution products; a styrene-methyl acrylate copolymer, a styrene-ethyl acrylate copolymer, a styrene-butyl acrylate copolymer, a styrene-octyl acrylate copolymer. Polymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-maleic acid copolymer, styrene-maleic acid ester Styrene copolymers such as copolymers; polymethylmethacrylate, polyesters, polyamides, epoxy resins, polyvinyl butyral, rosins, modified rosins,
Examples thereof include terpene resins, phenol resins, aliphatic or alicyclic hydrocarbon resins, aromatic petroleum resins and the like, and these can be used alone or in combination.

As the colorant, carbon black, titanium black, magnetic powder, oil black, titanium white, or any pigment and / or dye can be used. Black carbon black has a primary particle size of 20-
Those having a thickness of 40 nm are preferably used. If it is less than 20 nm, the carbon black aggregates and is not uniformly dispersed in the toner, which may result in a toner with a large amount of fog. On the other hand, if it is larger than 40 nm, a large amount of a polycyclic aromatic hydrocarbon compound such as benzpyrene produced during the production of carbon black remains in the toner, which may cause environmental safety problems.

To obtain a full-color toner, yellow colorants, magenta colorants and cyan colorants are usually used. As the yellow colorant, compounds such as azo pigments and condensed polycyclic pigments are used. Specifically, C.I. I. Pigment Yellow 3, 12, 13, 14, 15, 17,
62, 65, 73, 83, 90, 93, 97, 120,
138, 155, 180, 181, 185 and 186
Etc. As the magenta colorant, compounds such as azo pigments and condensed polycyclic pigments are used. Specifically, C.I. I. Pigment Red 48, 57, 58, 60,
63, 64, 68, 81, 83, 87, 88, 89, 9
0, 112, 114, 122, 123, 144, 14
6, 149, 163, 170, 184, 185, 18
7, 202, 206, 207, 209, 251, C.I.
I. Pigment Violet 19 and the like. As the cyan colorant, a copper phthalocyanine compound and its derivative, an anthraquinone compound, etc. can be used. Specifically, C.I. I. Pigment Blue 2, 3, 6, 15, 1
5: 1, 15: 2, 15: 3, 15: 4, 16, 17,
And 60 and the like. The amount of such a colorant is usually 1 to 10 parts by weight with respect to 100 parts by weight of the binder resin.

As the charge control agent, the charge control agents conventionally used for toners can be used. For example, Bontron N01 (manufactured by Orient Chemical Industry Co., Ltd.), Nigrosine Base EX (manufactured by Orient Chemical Industry Co., Ltd.), Spiron Black TRH (manufactured by Hodogaya Chemical Co., Ltd.), T-7.
7 (Hodogaya Chemical Co., Ltd.), Bontron S-34 (Orient Chemical Co., Ltd.), Bontron E-81 (Orient Chemical Co., Ltd.), Bontron E-84 (Orient Chemical Co., Ltd.), COPY CHARGE NX (Clariant) Made), COPY CHARGE NEG
(Manufactured by Clariant Co., Ltd.) and the like, and charge control agents such as JP-A-63-60458 and JP-A-3-175.
456, JP-A-3-243954, JP-A-11-15192, and the like, quaternary ammonium (salt) group-containing copolymers, JP-A-11-21746
It is also possible to synthesize a sulfonic acid (salt) group-containing copolymer in accordance with the description of JP-A No. 4 and JP-A-3-15858 and to use it as a charge control agent (charge control resin).

Among these, it is preferable to use the charge control resin. The charge control resin is preferable because it has high compatibility with the binder resin, is colorless, and can provide a toner having stable chargeability even in continuous color printing at high speed. The glass transition temperature of the charge control resin is usually 40-80.
C, preferably 45 to 75 ° C., more preferably 45 to 75 ° C.
It is 70 ° C. If it is lower than this range, the storage stability of the toner deteriorates, and conversely if it is higher, the fixing property may deteriorate. The amount of the charge control agent is usually 0. 0 with respect to 100 parts by weight of the binder resin.
The amount is 01 to 20 parts by weight, preferably 0.1 to 10 parts by weight.

Examples of the releasing agent include low molecular weight polyolefin waxes such as low molecular weight polyethylene, low molecular weight polypropylene, and low molecular weight polybutylene; plant-based natural waxes such as candelilla, carnauba, rice, and wax; paraffin, microcrystalline, Petroleum waxes such as petrol cutam; synthetic waxes such as Fischer-Tropsch wax; and polyfunctional ester compounds such as pentaerythritol tetramyristate, pentaerythritol tetrapalmitate, dipentaerythritol hexamyristate, and the like. These can be used alone or in combination of two or more.

Among these, synthetic wax (particularly Fischer-Tropsch wax), petroleum wax, polyfunctional ester compound and the like are preferable. Among the polyfunctional ester compounds, in the DSC curve measured by a differential scanning calorimeter, the endothermic peak temperature at the time of temperature rise is 30 to 120 ° C,
Preferably 40 to 100 ° C., more preferably 50 to 80
A polyvalent ester compound such as a pentaerythritol ester having a temperature range of 50 ° C. or a dipentaerythritol ester having an endothermic peak temperature of 50 to 80 ° C. is particularly preferable in terms of fixing-releasing balance as a toner,
Among them, styrene 1 has a molecular weight of 1000 or more.
It is more preferable to dissolve 5 parts by weight or more at 25 ° C. with respect to 00 parts by weight and to have an acid value of 10 mg / KOH or less, since a remarkable effect in lowering the fixing temperature is exhibited. Endothermic peak temperature is AST
It is the value measured by MD3418-82. The amount of the releasing agent is usually 0.5 to 50 parts by weight, preferably 1 to 20 parts by weight, based on 100 parts by weight of the binder resin.

Further, the toner used in the present invention may contain a magnetic material. Examples of the magnetic material include iron oxides such as magnetite, γ-iron oxide, ferrite, and iron-rich ferrite; metals such as iron, cobalt, and nickel; and metals such as aluminum, cobalt, copper, and lead,
Magnesium, tin, zinc, antimony, beryllium, bismuth, cadmium, calcium, manganese, selenium,
Examples thereof include alloys with metals such as titanium, tungsten and vanadium, and mixtures thereof.

The toner used in the present invention preferably has an external additive attached or partially embedded on the surface of the toner particles. Examples of the external additive include inorganic particles and organic resin particles, and it is preferable to use inorganic particles and organic resin particles in combination. To attach the external additive to the polymer particles, the external additive and the polymer particles are usually charged in a mixer such as a Henschel mixer and stirred.

In a further preferred embodiment of the toner used in the present invention, the primary particles have an average particle size of 5 to 18 nm, preferably 7 to 16 nm, and the average particle size of the silica particles (A) is 0.05. ˜1 μm, preferably 0.1˜0.
An external additive containing organic or inorganic fine particles (C) of 8 μm is added to the toner particles. The external additive has an average primary particle diameter of 20 to 60 nm, preferably 25 to
It is more preferable to contain 50 nm of silica fine particles (B). By attaching or embedding an external additive to the surface of the particles, the chargeability, fluidity, storability, etc. of the particles can be adjusted.

If the average particle size of the silica fine particles (A) is small, the photosensitive member is likely to cause filming, and conversely, if the average particle size is large, the fluidity is deteriorated, and the particles may be easily scraped. When the average particle size of the silica fine particles (B) is small, the photoreceptor is likely to cause filming, and when the average particle size is large, the fluidity is lowered and the particles may be easily scraped. When the average particle size of the organic or inorganic fine particles (C) is small, the polishing property may be reduced, and when the average particle size is large, the fluidity may be decreased.

The silica fine particles (A) or the silica fine particles (B) are not particularly limited, but are preferably hydrophobized. Hydrophobicized silica fine particles are generally commercially available, but they can also be obtained by hydrophobizing them with a silane coupling agent or silicone oil. As a method of hydrophobizing treatment, a method of dropping or spraying a treating agent such as silicone oil while stirring the fine particles at high speed, and adding and mixing the fine particles into an organic solvent in which the treating agent is dissolved and stirred , A method of heat treatment, and the like. In the former case, the treating agent may be diluted with an organic solvent or the like. The degree of hydrophobicity is such that the degree of hydrophobicity measured by the methanol method is 20 to 90%. Preferably 40-
80%. If the degree of hydrophobicity is small, it tends to absorb moisture under high humidity, and if the degree of hydrophobicity is too high, sufficient polishing properties may not be obtained.

The organic fine particles are not particularly limited, but the compound constituting the fine particles usually has a glass transition temperature or melting point of 80 to 80 from the viewpoint of suppressing blocking between particles.
The temperature is 250 ° C, preferably 90 to 200 ° C. Examples of the compound that constitutes the organic fine particles include a methyl methacrylate polymer and a styrene-methyl methacrylate copolymer. The sphericity (Sc / Sr) obtained by dividing the area (Sc) of the circle having the absolute maximum length of the particle as the diameter by the substantial projected area (Sr) of the particle is not particularly limited, but is usually 1 to 1.
3, preferably 1 to 1.2. If the sphericity is large, the transferability may decrease.

Examples of the inorganic fine particles include silica, titanium oxide, aluminum oxide, zinc oxide, tin oxide, barium titanate, strontium titanate, and those to which electroconductivity is imparted by surface-treating them with tin or antimony. Can be mentioned.

The amount of the silica fine particles (A) added is not particularly limited, but is usually 0.1% with respect to 100 parts by weight of the toner particles.
It is 1 to 3 parts by weight, preferably 0.2 to 2 parts by weight. If this amount is too small, the fluidity may be reduced to cause scraping, and conversely if the amount is too large, the fluidity may be increased and fogging may be likely to occur. The amount of the silica fine particles (B) added is not particularly limited, but is usually 0.1 to 1 part by weight, preferably 0.2 to 0.7 part by weight, relative to 100 parts by weight of the toner particles. If this amount is too small, the polishing property may be deteriorated and filming may occur. On the contrary, if the amount is too large, the fluidity may be deteriorated and the film may be easily scraped. The addition amount of the organic or inorganic fine particles (C) is not particularly limited, but the toner particles 10
It is usually 0.1 to 2 parts by weight, preferably 0.2 to 1 part by weight, based on 0 part by weight. If the amount is less than this amount, filming may occur, and conversely if the amount is greater, the fluidity may be lowered and the image may be easily scraped.

The attachment or partial embedding of the external additive is usually carried out by placing the external additive and the toner particles in a mixer such as a Henschel mixer and stirring the mixture.

The toner used in the present invention is not limited by its manufacturing method. For example, after a colorant, a charge control agent, a release agent, etc. are melt-mixed and uniformly dispersed in a thermoplastic resin serving as a binder resin component to form a composition, the composition is pulverized and classified. By a pulverizing method to obtain a toner, a colorant, a charge control agent, a release agent and the like are dissolved or dispersed in a polymerizable monomer that is a binder resin raw material, and after adding a polymerization initiator,
A polymerization method in which a toner is suspended in an aqueous dispersion medium containing a dispersion stabilizer, heated to a predetermined temperature to start polymerization, and filtered, washed, dehydrated and dried after completion of polymerization,
Binder resin particles obtained by emulsion polymerization or suspension polymerization are associated with particles containing a colorant and a charge control agent, and the associated particles are heat-treated, filtered and dried to obtain a toner. Obtaining the association method, using a hydrophilic group-containing resin as a binder resin, adding a colorant, a charge control agent, etc. to it and dissolving it in an organic solvent, neutralizing the resin, phase inversion, and then drying. It can be produced by a phase inversion emulsification method or the like for obtaining a toner. From the viewpoint of obtaining a toner that gives good image quality with good dot reproducibility, it is preferably produced by a polymerization method, and more preferably polymerized in the presence of a compound containing boron or phosphorus. In the polymerization method, the polymerization of the polymerizable monomer composition can be carried out by any of emulsion polymerization, suspension polymerization, precipitation polymerization and soap-free polymerization. The suspension polymerization method is preferable from the viewpoint that the property can be improved. Hereinafter, the method for producing a toner will be described by taking the suspension polymerization method as an example.

Examples of the polymerizable monomer for obtaining the binder resin include monovinyl monomer, crosslinkable monomer, macromonomer and the like. This polymerizable monomer is polymerized and becomes a binder resin component in the polymer particles. As the monovinyl monomer, specifically, styrene, vinyltoluene,
Aromatic vinyl monomers such as α-methylstyrene; (meth)
Acrylic acid; methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, (meth)
Butyl acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, glycidyl (meth) acrylate,
Examples include derivatives of (meth) acrylic acid such as 2-hydroxyethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, and (meth) acrylamide; monoolefin monomers such as ethylene, propylene, and butylene; and the like. . The monovinyl monomer may be used alone or in combination of a plurality of monomers. Of these monovinyl monomers, an aromatic vinyl monomer alone, a combination of an aromatic vinyl monomer and a (meth) acrylic acid derivative, and the like are preferably used.

Use of a crosslinkable monomer or a crosslinkable polymer together with the monovinyl monomer is effective for improving hot offset. The crosslinkable monomer is a monomer having two or more polymerizable carbon-carbon unsaturated double bonds. In particular,
Aromatic divinyl compounds such as divinylbenzene, divinylnaphthalene, and their derivatives; Diethylenically unsaturated carboxylic acid esters such as ethylene glycol dimethacrylate and diethylene glycol dimethacrylate;
Examples thereof include compounds having two vinyl groups such as N, N-divinylaniline and divinyl ether, and compounds having three or more vinyl groups such as pentaerythritol triallyl ether and trimethylolpropane triacrylate. The crosslinkable polymer is a polymer having two or more vinyl groups in the polymer, and specifically, such as polyethylene, polypropylene, polyester and polyethylene glycol having two or more hydroxyl groups in the molecule. An ester obtained by subjecting a polymer and an unsaturated carboxylic acid monomer such as acrylic acid or methacrylic acid to a condensation reaction can be mentioned. These crosslinkable monomers and crosslinkable polymers may be used alone or in combination of two or more. The amount used is usually 10 parts by weight or less, preferably 0.1 to 2 parts by weight, per 100 parts by weight of the monovinyl monomer.

Further, it is preferable to use a macromonomer together with the monovinyl monomer, since a good balance between storage stability and low temperature fixability will be obtained. The macromonomer has a vinyl polymerizable functional group at the end of the molecular chain, and is an oligomer or polymer having a number average molecular weight of usually 1,000 to 30,000. When a polymer having a small number average molecular weight is used, the surface portion of the polymer particles becomes soft and the storage stability is deteriorated. On the other hand, when a polymer having a large number average molecular weight is used, the meltability of the macromonomer deteriorates and the fixability deteriorates. Examples of the vinyl polymerizable functional group at the end of the macromonomer molecular chain include an acryloyl group and a methacryloyl group, and a methacryloyl group is preferable from the viewpoint of ease of copolymerization.

The macromonomer preferably has a glass transition temperature higher than the glass transition temperature of the polymer obtained by polymerizing the monovinyl monomer. Specific examples of the macromonomer used in the present invention include a polymer obtained by polymerizing styrene, a styrene derivative, a methacrylic acid ester, an acrylic acid ester, acrylonitrile, methacrylonitrile or the like, or a polysiloxane skeleton. Among them, hydrophilic monomers, particularly polymers obtained by polymerizing methacrylic acid esters or acrylic acid esters alone or in combination thereof are preferable.
When a macromonomer is used, the amount thereof is usually 0.01 to 10 parts by weight, preferably 0.03 to 5 parts by weight, and more preferably 0.05 to 100 parts by weight of the monovinyl monomer. ~ 1 part by weight. If the amount of macromonomer is small, the storage stability will not be improved. If the amount of macromonomer becomes extremely large, the fixability will decrease.

Examples of the dispersion stabilizer include sulfates such as barium sulfate and calcium sulfate; carbonates such as barium carbonate, calcium carbonate and magnesium carbonate; phosphates such as calcium phosphate; metal oxides such as aluminum oxide and titanium oxide. Compounds; metal compounds such as aluminum hydroxide, magnesium hydroxide, ferric hydroxide; water-soluble polymers such as polyvinyl alcohol, methyl cellulose, gelatin; anionic surfactants, nonionic surfactants Examples thereof include agents and amphoteric surfactants, which may be used alone or in combination of two or more kinds. Among these, a dispersion stabilizer containing a metal compound, particularly a colloid of a sparingly water-soluble metal hydroxide, can narrow the particle size distribution of polymer particles, and the dispersion stabilizer remains after washing. Is preferable and an image can be reproduced clearly, which is preferable.

The dispersion stabilizer containing a colloid of poorly water-soluble metal hydroxide is not limited by its production method, but it is obtained by adjusting the pH of the aqueous solution of the water-soluble polyvalent metal compound to 7 or more. Metal hydroxide colloid,
Particularly, it is preferable to use a colloid of a poorly water-soluble metal hydroxide, which is produced by the reaction of the water-soluble polyvalent metal compound and the alkali metal hydroxide in the aqueous phase.

The slightly water-soluble metal hydroxide colloid has a number particle size distribution D50 (50% cumulative value of the number particle size distribution) of 0.
D90 (90% cumulative value of number particle size distribution) at 5 μm or less
Is preferably 1 μm or less. If the particle size of the colloid becomes large, the stability of polymerization will deteriorate and the storage stability of the toner will also deteriorate.

The dispersion stabilizer is usually used in a proportion of 0.1 to 20 parts by weight with respect to 100 parts by weight of the polymerizable monomer. If this ratio is less than 0.1 part by weight, it is difficult to obtain sufficient polymerization stability, and polymer aggregates are easily generated. On the other hand, if it exceeds 20 parts by weight, the toner particle size after polymerization becomes too fine, which is not practical.

The toner used in the present invention is preferably polymerized in the presence of a compound containing boron or phosphorus.
The boron- or phosphorus-containing compound that can be used at this time is a water-soluble compound that is soluble in water. It may be one that is added to water and then decomposes and dissolves in water. Examples of compounds containing boron include boron trifluoride, boron trichloride; tetrafluoroboric acid, sodium tetrahydroborate, potassium tetrahydroborate; sodium tetraborate, sodium metaborate, sodium peroxoborate, boric acid, metaborate. Examples thereof include potassium acid and hydrates thereof.

As the compound containing phosphorus, phosphoric acid,
Phosphonic acid, phosphinic acid, metaphosphoric acid, diphosphoric acid; sodium phosphinate, sodium phosphonate, sodium phosphate, disodium hydrogen phosphate, sodium dihydrogen phosphate, sodium hypophosphate, sodium diphosphate,
Disodium dihydrogen diphosphate, sodium triphosphate, c
yclo-sodium tetraphosphate, potassium phosphinate, potassium phosphonate, potassium hydrogen phosphonate, potassium phosphate, dipotassium hydrogen phosphate, potassium dihydrogen phosphate, potassium diphosphate, potassium metaphosphate, and hydration thereof The thing etc. are mentioned. Of these, compounds containing boron, especially tetraborate, are preferred.

As the polymerization initiator, persulfates such as potassium persulfate; 4,4′-azobis (4-cyanovaleric acid),
2,2'-azobis (2-methyl-N- (2-hydroxyethyl) propionamide, 2,2'-azobis (2
-Amidinopropane) dihydrochloride, 2,2'-
Azobis (2,4-dimethylvaleronitrile), 2,
Azo compounds such as 2'-azobisisobutyronitrile; lauroyl peroxide, benzoyl peroxide, t-
Butyl peroxy-2-ethyl hexanoate, t-hexyl peroxy-2-ethyl hexanoate, t-butyl peroxypivalate, di-isopropyl peroxydicarbonate, 1,1,3,3-tetramethyl Examples thereof include peroxides such as butylperoxy-2-ethylhexanoate and t-butylperoxyisobutyrate.

Among these, it is particularly preferable to select an oil-soluble polymerization initiator that is soluble in the polymerizable monomer used, and a water-soluble polymerization initiator can be used in combination therewith if necessary. . The polymerization initiator is a polymerizable monomer 10
0.1 to 20 parts by weight, preferably 0.3 to 15 parts by weight, and more preferably 0.5 to 10 parts by weight, relative to 0 parts by weight. The polymerization initiator may be added in advance to the polymerizable monomer composition, but in the case of suspension polymerization, a suspension after the granulation step or in the middle of the polymerization reaction, in the case of emulsion polymerization the emulsification step After the completion of the polymerization or during the polymerization reaction, the emulsion may be directly added.

Further, it is preferable to add a molecular weight modifier during the polymerization. As the molecular weight modifier, for example,
t-dodecyl mercaptan, n-dodecyl mercaptan, n-octyl mercaptan, 2,2,4,6,6-
Examples thereof include mercaptans such as pentamethylheptane-4-thiol; halogenated hydrocarbons such as carbon tetrachloride and carbon tetrabromide; These molecular weight modifiers can be added before the start of the polymerization or during the polymerization. The molecular weight modifier is usually 0.01 to 10 parts by weight, preferably 0.1 to 100 parts by weight of the polymerizable monomer.
It is used in a proportion of up to 5 parts by weight.

In the suspension polymerization method, which is a preferable method for producing the toner used in the present invention, a polymerizable monomer, a colorant, a charge control agent and other additives are added in an aqueous dispersion medium containing a dispersion stabilizer. The polymerizable monomer composition containing the agent is suspended and polymerized using a polymerization initiator. Examples of other additives include the release agents, magnetic materials, water-soluble boron- or phosphorus-containing compounds, and molecular weight modifiers described above.

As the toner of the present invention, the toner obtained by the above-mentioned manufacturing method can be used as it is, but a core shell type toner can also be used. Examples of the method for producing the core-shell type toner include a spray dry method, an interfacial reaction method, an in situ polymerization method, a phase separation method, and the like, which are obtained by a pulverization method, a polymerization method, an association method, or a phase inversion emulsification method. A core-shell type toner is obtained by using the toner as a core particle and coating the shell layer on the toner.
At this time, an in situ polymerization method or a phase separation method is preferable from the viewpoint of production efficiency.

The method for producing the core-shell type toner by the in situ polymerization method will be described below. A core-shell type toner is obtained by adding a polymerizable monomer for forming a shell (polymerizable monomer for shell) and a polymerization initiator to an aqueous dispersion medium in which core particles are dispersed and polymerizing. be able to. As a specific method for forming the shell, a method of continuously adding a polymerizable monomer for a shell to a reaction system of a polymerization reaction carried out to obtain a core particle and continuously polymerizing it, or a method using another reaction system is used. Another method is to charge core particles, add a polymerizable monomer for shell to the core particles, and perform stepwise polymerization. The polymerizable monomer for shell may be added to the reaction system all at once, or may be added continuously or intermittently using a pump such as a plunger pump.

As the polymerizable monomer for the shell, styrene, acrylonitrile, methyl methacrylate and the like which form a polymer having a glass transition temperature of more than 80 ° C. may be used alone or in combination of two or more kinds. be able to.

When the polymerizable monomer for the shell is added, it is preferable to add a water-soluble radical initiator because it facilitates obtaining the core-shell type toner. When the water-soluble radical initiator is added during the addition of the shell polymerizable monomer, the water-soluble radical initiator enters near the outer surface of the core particle to which the shell polymerizable monomer has migrated, and the core particle surface It is considered that this is because it becomes easy to form a polymer (shell).

As water-soluble radical initiators, persulfates such as potassium persulfate and ammonium persulfate; 4,4′-
Azobis (4-cyanovaleric acid), 2,2′-azobis (2-amidinopropane) dihydrochloride,
Azo initiators such as 2,2′-azobis-2-methyl-N-1,1′-bis (hydroxymethyl) -2-hydroxyethylpropioamide; oil-soluble initiators such as cumene peroxide and redox catalysts And the like; and the like. The amount of the water-soluble radical initiator is usually 1 to 50% by weight, preferably 2 to 20% by weight, based on 100 parts by weight of the shell monomer.

The aqueous dispersion of the obtained toner (polymer particles) is acid-washed with stirring while adjusting the system pH to about 5.0 with sulfuric acid. Then, after dehydration using a filter, washing water is sprinkled to perform water washing. By repeating this, the dispersion stabilizer can be removed and the content of boron or phosphorus in the toner can be adjusted.
After washing and dehydration are completed, the toner particles that can be used in the present invention are obtained by drying.

As an example of the developing method of the present invention, the surface of the latent image carrier is uniformly charged by a charging roll, an electrostatic latent image is formed on the surface of the latent image holding member by exposing the surface, and the electrostatic latent image is formed by a supply roll. The above-mentioned toner is supplied to the developing roll, the toner layer thickness of the supplied toner is adjusted by a layer thickness regulating blade, and the electrostatic latent image formed on the latent image holding member is formed by the toner on the developing roll. The step of developing into a toner image is included. The image forming method of the present invention further includes a step of fixing the toner image obtained by the above-described developing method after transferring the toner image to a transfer material.

The developing method and image forming method of the present invention will be described in detail below with reference to the drawings. FIG. 2 is a diagram showing an example of an image forming apparatus to which the developing method and the image forming method of the present invention can be applied. As shown in FIG. 2, the image forming apparatus has a photosensitive drum 1 as a latent image holder, which is mounted rotatably in the direction of arrow A. The photosensitive drum 1 has a photoconductive layer provided on a conductive support drum, and the photoconductive layer includes, for example, an organic photoconductor, a selenium photoconductor, a zinc oxide photoconductor, an amorphous silicon photoconductor, and the like. , Preferably composed of an organic photoreceptor.
Examples of the resin for binding the photoconductive layer to the conductive support drum include polyester resin, acrylic resin, polycarbonate resin, phenol resin, epoxy resin, hydrogenated polystyrene resin, and the like, and among them, polycarbonate resin is preferable.

Around the photosensitive drum 1, a charging roll 3, a laser beam irradiation device 4 as an exposure device, a developing device 11, a transfer roll 5, and a cleaning device 2 are arranged along the circumferential direction. The charging is to charge the surface of the photosensitive drum 1 positively or negatively with the above-mentioned charging roll.

The exposure is to irradiate the latent image carrier charged by the exposure device with light. For example, a laser light irradiation device 4 shown in FIG. 2 is used as the exposure device.
The surface of the photosensitive drum can be irradiated with light corresponding to an image signal to form an electrostatic latent image on the surface of the charged drum. The laser light irradiation device 4 is composed of, for example, a laser irradiation device and an optical system lens. In addition to this, as an exposure device, there is an LED irradiation device.

The developing device 11 shown in FIG. 2 is a developing device used in the one-component contact developing system, and has a developing roll 7 and a supply roll 9 in a casing 12 in which the toner 10 is accommodated. The developing roll 7 is arranged so as to partially contact the photosensitive drum 1, and is rotated in the direction B opposite to the photosensitive drum 1. The supply roll 9 contacts the developing roll 7, rotates in the same direction C as the developing roll 7, and supplies the toner 10 to the outer periphery of the developing roll 7. Other developing methods include a one-component non-contact developing method, a two-component non-contact developing method, and a two-component non-contact developing method.

For the development, the toner is supplied to the developing roller 7 by the supply roller 9, the toner layer thickness of the supplied toner is adjusted by the layer thickness regulating blade 8, and the toner on the developing roller is applied to the latent image holding member. The toner corresponding to this is attached to the electrostatic latent image formed on. At this time, a bias is applied between the developing roll 7 and the photosensitive drum 1 so that the toner can be attached only to the light irradiation portion in the reversal development and the toner can be attached only to the light non-irradiation portion in the regular development. A voltage is applied.

In the casing of the developing device, a supply roll may be rotatably arranged in the vicinity of the developing roll in order to favorably adhere the toner to the outer peripheral surface of the developing roll.
A bias voltage is preferably applied to the conductive shaft of the developing roll. In the case of reversal development, a voltage having the same polarity as that of the electrostatic latent image on the latent image carrier is applied to the conductive shaft of the developing roll.

In the image forming apparatus according to the present invention, the rotation direction of the photosensitive drum is opposite to the rotation direction of the developing roll, and the peripheral speed of the developing roll is 1.
It is preferable that the photosensitive drum and the developing roll are rotationally controlled to be 1 time or more, preferably 1.2 times or more. Furthermore, the rotation direction of the supply roll and the rotation direction of the developing roll are the same, and the rotation speed is controlled so that the peripheral speed of the supply roll is 0.4 to 0.9 times the peripheral speed of the developing roll. It is preferable.

When the peripheral speed of the developing roll is less than 1.1 times the peripheral speed of the photosensitive drum, the developability may be deteriorated. In the present invention, the peripheral speed of the photosensitive drum is 30
It is preferably ˜150 mm / sec. The peripheral speed of the developing roll is preferably 33 to 200 mm / sec, provided that the peripheral speed is 1.1 times or more the peripheral speed of the photosensitive drum. The peripheral speed of the supply roll is preferably 12 to 135 mm / sec. The photosensitive drum, the developing roll and the supply roll are, for example, rotationally driven by a motor. The motor that rotationally drives the photosensitive drum, the developing roll, and the supply roll may be a common motor. The peripheral speeds of the photosensitive drum, the developing roll, and the supply roll are set by a speed reducing mechanism or a speed increasing mechanism. Further, these peripheral speeds may be variably configured by a gear mechanism or a variable rotation speed motor. These peripheral speeds may be controlled by a microcomputer or the like.

The photosensitive drum is so adjusted that the axial distance between the photosensitive drum axis and the developing roller axis is smaller than the sum of the radius of the photosensitive drum and the developing roller by 0.05 to 0.20 mm. On the other hand, it is preferable to arrange the developing roll by pressing it. If the axial distance is too short, the rotational power may increase, and if the axial distance is too long, the desired print density may not be obtained.

As shown in FIG. 3, this developing roll is constructed by covering the outer circumference of the conductive shaft 71 with a rubber elastic body 72. The conductive shaft 71 is made of metal such as stainless steel. Conductive shaft 71
In order to cover the outer periphery of the rubber elastic body 72, the outer periphery of the conductive shaft 71 may be covered with the rubber elastic body 72 by means such as press molding and extrusion molding. in this case,
Extrusion molding is particularly preferable. This is because it is suitable for mass production, and unlike press molding, split mold lines are not formed.

The hardness of the rubber elastic body constituting the developing roll is preferably 35 to 45 degrees in accordance with JIS A standards. If the hardness is too high, the photosensitive drum may be damaged by abrasion, and if the hardness is too low, the toner layer becomes thick and fogging easily occurs, and good development may not be performed. The rubber elastic body constituting the surface of the developing roll is not particularly limited, but styrene-butadiene copolymer rubber, acrylonitrile-butadiene copolymer rubber, acrylic rubber, epichlorohydrin rubber, urethane rubber, silicone rubber, etc. A blend rubber of epichlorohydrin rubber and acrylonitrile-butadiene copolymer rubber is preferably used.

When the developing roll preferably used in the present invention is composed of a conductive shaft and a rubber elastic body, the electric resistance between the surface of the rubber elastic body and the surface of the conductive shaft is 105 to 108 Ω ( (At the time of applying a voltage of 500 V), or the volume resistivity is preferably 107 to 1010 Ω · cm. If the resistance of the rubber elastic body is too low, a current may flow from the developing roll to the photosensitive drum, and the electric charge of the toner may leak to the developing roll, which is not preferable. If the resistance of the rubber elastic body is too high, the effect of the bias voltage may not appear.

The developing roll used in the present invention is not particularly limited, but its surface friction coefficient is usually 0.1 to 1.
2, preferably 0.1 to 0.8, more preferably 0.1
5 to 0.6. If the friction coefficient of the surface of the developing roll is too small, the surface of the roll may slip too much and the toner layer may become thin, resulting in a decrease in print density. Conversely, if it is too large, the toner layer may become too thick and the fog on the photoreceptor may be reduced. Paper fog may occur. At this time, the friction coefficient was measured by replacing the charging roll 3 in FIG. 1 with a developing roll.

As means for adjusting the surface of the developing roll to a friction coefficient within the above range, the outer peripheral surface of the developing roll is polished by a cylindrical cutting machine or the like, and if necessary, coated with urethane resin, and then irradiated with ultraviolet rays. A means for adjusting the friction coefficient within the above range by crosslinking the unsaturated part of the rubber elastic body can be adopted. UV irradiation is, for example, 80 W /
Irradiate for 2-3 minutes using a cm light source.

The developing roll used in the present invention is
The circumferential surface roughness of the surface is 10 μm or less, and the axial surface roughness of the surface is 10 μm or less. In the present invention, the circumferential surface roughness and the axial surface roughness are 1
If it is 0 μm or less, it may approach 0 without limit,
Considering mass productivity and economical efficiency, the thickness is preferably about 4 to 8 μm. If the surface roughness in the circumferential direction is larger than 10 μm,
It is not preferable because a uniform toner layer cannot be formed along the circumferential direction and the resolution may be lowered. If the surface roughness in the axial direction is larger than 10 μm, it is not preferable because a uniform toner layer cannot be formed along the axial direction and the resolution may decrease.

As means for making the surface of the developing roll to have a surface roughness within the above range, means for polishing the outer peripheral surface of the rubber elastic body with a cylindrical cutting machine or the like can be used. Polishing is first performed with a coarse cutting file or grindstone, and finally with a fine file or grinding wheel or wet polishing.

The supply roll used in the present invention is not particularly limited, and for example, a roll in which the outer peripheral surface of the conductive shaft is covered with a conductive rubber elastic body or a foam thereof can be used. Examples of the rubber elastic body that can form the outer peripheral surface of the supply roll include silicon rubber, urethane rubber, and chloroprene rubber, and these foams are preferably used.

The form of the layer thickness regulating blade used in the present invention is not particularly limited, but it is preferable that the blade has a band shape that is in contact with the developing roller along the axial direction. The base end of the blade is supported by a holder 50 made of a rigid body, as shown in FIG.

In the present invention, as shown in FIG. 4 (a), the tip of the free end of the blade bends to the outer circumference of the developing roll, and the free end bends to the base end in the direction opposite to the rotating direction of the developing roll. Is preferably in contact with. The length of this blade (length from fixed end to free end: free end length 1) is not particularly limited, but is preferably 10 to 14 mm.
Further, the thickness t of the blade is preferably 1.0 to 1.8.
It is about mm. The width of the blade has a length corresponding to the axial length of the developing roll. The free end of the blade may have a shape of a gentle arc, or may have a shape having an acute angle, a right angle, or an obtuse angle.

The layer thickness regulating blade used in the present invention is
For example, the rubber elastic body is composed of a metal plate whose sole end is in contact with the developing roller or which is covered with the rubber elastic body. A conductive substance, a cross-linking agent, or the like can be added to this rubber elastic body. The compression set of the rubber elastic body is preferably 10% or less, more preferably 4 to 8%.
The smaller the compression set, the better, but it cannot be set to 0 in reality, so the range is in the above range. The compression set is measured according to JIS K6262.

When the compression set exceeds 10%, the blade pressed against the developing roll is subject to permanent set, and the linear pressure of the blade against the roll may decrease over time.
The rebound resilience of the layer thickness regulating blade preferably used in the present invention is preferably 30 to 50%. The impact resilience is measured by the Lupke method (JISK6255). If the impact resilience is less than 30%, the plastic deformation of the material becomes large, and as a result, the toner layer on the developing roll may become thick, and if it exceeds 50%, the elasticity of the material becomes strong and the toner layer becomes thin. It can happen too much.

The Young's modulus of the rubber elastic body is 600 to 120.
It is preferably 0 g / mm 2. If this is small,
There is a tendency that the toner layer becomes too thick because of insufficient pressure contact with the developing roll. On the other hand, if it is large, the pressing force to the developing roll is too large, and the toner layer may be too thin. Further, in this case, the rotational torque applied to the developing roll increases, and a phenomenon such as jitter (horizontal stripes corresponding to the number of teeth of the developing roll driving gear) may occur. The Young's modulus is measured according to the low extension stress test described in JIS K6301.

In order to inject charge into the toner, the layer thickness regulating blade has a developing bias of -200V to -60V.
A direct current voltage of 0 V is preferably applied. Therefore, the electric resistance of the layer thickness regulating blade is preferably 106Ω or less, and more preferably 104 to 106Ω. This electric resistance is preferably low, but since it is necessary to give the blade conductivity, a conductive material such as carbon is put in the rubber elastic body to reduce the resistance, so the content of the conductive material is reduced. May increase the hardness of the rubber too much.

The electric resistance of this layer thickness regulating blade is 106
If it exceeds Ω, the impedance becomes high and the effect of the bias voltage may not appear. As the method for measuring the electric resistance of the layer thickness regulating blade, a method of measuring the electric resistance between the corner of the blade where the blade comes into contact with the developing roll and the holder for fixing the blade with an insulation resistance meter (applied voltage 500 V) is adopted. To do.

In order to set the compression set, rebound elastic modulus and Young's modulus of the rubber elastic body constituting the layer thickness regulating blade within the above ranges, the vulcanization conditions such as the addition amount of the crosslinking agent contained in the rubber elastic body are selected. It is done by doing. For example, in order to obtain a rubber elastic body having a small compression set, it is preferable to increase the addition amount of the crosslinking agent, increase the crosslinking temperature, and lengthen the crosslinking time. Further, in order to set the electric resistance of the layer thickness regulating blade preferably used in the present invention to 106 Ω or less, the content of the conductive substance such as conductive carbon black contained in the rubber elastic body forming the blade 9 is adjusted. It is done by For example, when the rubber elastic body forming the blade is made of urethane rubber, when the total amount of the rubber elastic body is 100 parts by weight, the addition amount of the conductive carbon black is set to 5 to 30 parts by weight so that the electrical conductivity can be improved. The resistance can be set within the above range.

The rubber elastic material constituting this blade is not particularly limited, but styrene-butadiene copolymer rubber, acrylonitrile-butadiene copolymer rubber,
Acrylic rubber, epichlorohydrin rubber, urethane rubber, silicone rubber, etc., preferably urethane rubber, acrylonitrile-butadiene copolymer rubber, etc. are used.

It is preferable that the free end of the blade is brought into contact with the outer periphery of the developing roll, and the free end is bent in a direction opposite to the direction of rotation of the developing roll with respect to the base end. In the present invention, as shown in FIG. 4 (b), the bending amount δ of the blade tip due to bending of the free end of the blade is preferably 2 to 5 mm as compared with the blade tip before bending. .

If the deflection amount δ at the tip of the blade is smaller than 2 mm, the linear pressure of the blade is insufficient, and the toner layer on the developing roll may be too thick. If it is larger than 5 mm, the linear pressure is excessive. And excessive stress is applied to the toner, and a so-called jitter phenomenon may occur. In the present invention, the linear pressure f when the blade is attached to the developing roll is preferably 0.7 to 2
g / mm, more preferably 1 to 1.5 g / mm.

If the linear pressure is too low, the toner layer on the developing roll may become too thick, and if the linear pressure is too high, excessive stress is generated on the toner on the developing roll and the toner layer is thin. Sometimes it becomes too much. In addition,
The linear pressure f (g / mm) is defined by the following mathematical formula. f = t3δE / 4l3 In this equation, t is the blade thickness (mm), δ is the blade deflection (mm), and E is the blade Young's modulus (g).
/ Mm2), l is the free end length (mm) of the blade.

In the present invention, the contact angle of the blade with the developing roll is not particularly limited, but is preferably 75 to 85 degrees, more preferably 80 to 85 degrees. If the contact angle is less than 75 degrees, the toner layer formed on the surface of the developing roll may be too thin, and if the contact angle is too small, the blade may be turned up by the rotation of the developing roll. . When the contact angle is larger than 85 degrees, the toner layer becomes too thick, and when the contact angle becomes too large, the abdomen of the blade comes into contact with the outer peripheral surface of the developing roll, and the toner layer becomes extremely thick. . The contact angle is an angle formed by the tangent line of the outer circumference of the developing roll passing through the point where the layer thickness regulating blade comes into contact with the developing roll, and the tip surface of the blade.

Transfer is to transfer the toner image on the surface of the photosensitive drum formed by the developing device 11 to the transfer material 6 such as paper by applying a transfer voltage having a polarity opposite to that of the toner by the transfer device. Normally, a transfer roll 5 as shown in FIG. 2 is used as the transfer device, but other than that, there are belt transfer and corona transfer.

The fixing means fixing the toner image transferred onto the transfer material 6 such as paper so as not to be separated from the transfer material. Usually, heat fixing is carried out by using two rolls (heating roll 13 and pressure roll 14) as shown in FIG. There are two types of pressure fixing, that is, fixing by pressure, flash fixing using a xenon lamp without using a roll at all, and solvent fixing using an organic solvent.

Although not necessary when cleaning is performed at the same time as development, a cleaning process for removing the toner remaining on the surface of the photosensitive drum by the cleaning device 2 may be provided between the transfer roll and the charging member. preferable. Normally, a cleaning blade is used for this cleaning device, but fur brush,
Cleaning with a magnetic brush, a cleaning roll, and static electricity has also been proposed.

In the image forming apparatus shown in FIG. 2, the surface of the photosensitive drum 1 is uniformly charged with the negative polarity by the charging roll 3, and then an electrostatic latent image is formed by the laser beam irradiating device 4. The developing device 11 develops the toner image. Subsequently, the toner image on the photosensitive drum 1 is transferred onto a transfer material 6 such as paper by the transfer roll 5, and is fixed on the transfer material by two fixing rolls (heating roll 13 and pressure roll 14). If necessary, the transfer residual toner remaining on the surface of the photosensitive drum is cleaned by the cleaning device 2, and then the next image forming cycle is started.

The image forming apparatus shown in FIG. 2 is for monochrome, but the developing method and the image forming method of the present invention are
It can also be applied to color image forming apparatuses such as copiers and printers that form color images. As a color image forming apparatus, a multi-development method in which a multi-color toner image is developed on a photoconductor and is transferred to a transfer material at once is used. There is a multiple transfer system in which the transfer of the color toner is repeated for the number of colors of the color toner. In the multiple transfer method, a transfer material is wound around a transfer drum and transfer is performed for each color, and primary transfer is performed for each color on an intermediate transfer body, and a multicolor image is formed on the intermediate transfer body. After the formation, the intermediate transfer method in which the secondary transfer is performed at once, the developing devices are arranged in tandem around the photoconductor, and the transfer material is adsorbed and conveyed by the transfer conveyance belt, and each color is sequentially transferred to the transfer material. There is a tandem system. Among these, a tandem type image forming apparatus capable of performing image formation at high speed is preferable.

FIG. 5 is a schematic view showing an example of a tandem type color image forming apparatus to which the image forming method of the present invention can be applied. The tandem-type color image forming apparatus is provided with an image forming unit including a laser beam irradiating device 4, a photosensitive drum 1, a developing device 11, and a cleaning device 2 as many as the number of toner colors used. The image forming units are normally arranged in the order of yellow, magenta, cyan, and black along the conveyor belt 15, and the images formed by the image forming units are attracted to the conveyor belt and conveyed. The transfer roll 7 transfers the image onto the transfer material 7 so that the transfer material 7 is sequentially overlaid and fixed. As described above, the transfer material is generally conveyed by a conveyor belt, but it can also be adsorbed on the transfer drum and conveyed. in this case,
The image forming units are arranged in order along the transfer drum. In addition, Y of the alphabet shown in FIG.
M, C, and K respectively correspond to the colors of toner of the image forming units, namely yellow, magenta, cyan, and black.

[0119]

EXAMPLES The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. In addition, part and%
Is weight basis unless otherwise specified. In this example, the following methods were used for evaluation.

[Evaluation Method] (Volume Average Particle Diameter) The volume average particle diameter (dv) of the toner and the particle diameter distribution, that is, the ratio (dv / dp) of the volume average particle diameter to the number average particle diameter (dp) are calculated by Multisizer. (Manufactured by Beckman Coulter, Inc.). The measurement with this Multisizer was performed under the conditions of an aperture diameter: 100 μm, a medium: Isoton II, a concentration of 10%, and the number of measured particles: 100,000.

(Number average particle size) The number average particle size of the organic fine particles is determined by taking an electron microscope photograph of each particle and using the image processing / analyzing apparatus Luzex IID (manufactured by Nireco) to determine the area of the particles with respect to the frame area. Ratio: maximum 2%, total number of treated particles: average value for 100 circle-equivalent diameters measured under the conditions of 100 pieces.

(Sphericality) Sphericality (Sc / Sr) is the area of a particle with respect to the frame area, taken by taking an electron micrograph of each particle and using the image processing analyzer Luzex IID (manufactured by Nireco Corporation). The ratio is a maximum of 2%, and the total number of treated particles is 100. The value obtained by dividing the area of the maximum outer circle by the substantial cross-sectional area is measured, and is the average value of the measured values.

(Volume Specific Resistance) A charging roll is fixed with its metal core material, a brass electrode having a width of 2 mm and a weight of 500 g is placed on the surface of the charging roll, and the metal core material and brass of the charging roll are made. A DC voltage of 500 V was applied between the electrodes, and the electric resistance of the charging roll was measured. The measured electrical resistance is R
(Ω), the contact area of the electrode is S (cm2), and the distance between the metal core and the electrode is L (cm), the volume resistivity ρ (Ω
-Cm) was calculated by the following formula. This time, contact area S
Is 4.6 cm2, the distance L between the metal core and the electrode
Was 0.3 cm. ρ = (R · S) / L The measurement is performed under two conditions of a temperature of 35 ° C. and a humidity of 80% (H / H) and a temperature of 10 ° C. and a humidity of 20% (L / L). did.

(Hardness) The hardness of the charging roll is JIS K
According to the rule of -6253, the rubber composition formed into a sheet by kneading was vulcanized at 155 ° C. to obtain a rubber sheet having a thickness of 2 mm, which was measured as a sample.

(Friction Coefficient) A charging roll is fixed to a moving body so that it does not move, a measuring paper of 2 cm × 20 cm is brought into contact with the charging roll so that the contact angle is 90 degrees, and a weight having a load of 50 g is attached to one end thereof. , A tension gauge was attached to the other end. The speed with the weight attached is 10
The moving body was pulled at 0 mm / min, the measurement paper started to move, and the numerical value (tension) when the tension gauge became stable was read. The measurement was performed 3 times, and the friction coefficient was calculated by the following formula. μs = 2 / π × Ln (F / W) where μs is the friction coefficient, W is the load suspended during measurement,
F is the average value of the measured tension.

(Paper Fogging) Using a commercially available non-magnetic one-component developing type printer (16-sheet machine), the toner to be evaluated was put into the developing device of this printer, and the temperature was 35 ° C. and the humidity was 80% (H / H). ) Under environment, temperature 10 ℃, humidity 2
After leaving it in the 0% (L / L) environment for a whole day and night, it continuously prints on the copy paper of the transfer material at a print density of 5%, measures the print density with a reflection densitometer (made by Macbeth) every 500 sheets, and prints. The fog on the non-image area of the transferred transfer paper was measured with a whiteness meter (manufactured by Nippon Denshoku). The final print number is 20,000. For fogging, the whiteness Y (%) of the non-image portion of the printed transfer material is measured, and the whiteness X (%) of the non-printed transfer material is measured. The difference obtained by subtracting Y from these measured values was obtained, and the number of printed sheets when this value exceeded 1% was counted. If the number in the table is 20000, it is 2
This indicates that fog of 1% or more did not occur even after continuous printing on ten thousand sheets.

(Dirt of charging roller) Using the above-mentioned printer, after leaving it for a whole day and night in an environment (L / L) of temperature 10 ° C. and humidity 20%, continuous printing was carried out on a copy paper as a transfer material at a print density of 5%. , Halftone printing is performed every 500 sheets. As the toner adheres to the charging roller, streaky stains appear on the copy paper. The number of appearing sheets is counted as charging roller contamination.

Reference Example 1 100 parts of styrene, 2.5 parts of sodium styrenesulfonate, 1.5 parts of sodium chloride, and 4000 parts of ion-exchanged water were added to a reaction vessel equipped with a stirrer and purged with nitrogen, and then mixed. , Raise the temperature to 80 ° C. After the temperature was raised, 2,2'-azobis [2-methyl-N-
(2-hydroxyethyl) propionamide] (trade name; "VA-086", manufactured by Wako Pure Chemical Industries, Ltd.) in 3% aqueous solution 5
Polymerization was initiated by adding 00 parts. On the way, while measuring the polymerization conversion rate, when the conversion rate reached 30%, 0.1 part of t-dodecyl mercaptan was added, and the polymerization was started at 7%.
The conversion was measured after 98 hours and was 98%. Next, 400 parts of methyl methacrylate was added over 15 minutes, and the polymerization was stopped by cooling with water after continuing the polymerization for 3 hours.
An aqueous dispersion of core-shell type organic fine particles was obtained. This time,
The polymerization conversion rate was 100%, the number average particle diameter of the organic fine particles was 0.38 μm, and the sphericity was 1.13.

(Toner Production Example 1) 80.5 parts of styrene,
Butyl acrylate 19.5 parts, carbon black (Mitsubishi Chemical Co., trade name # 25) 7 parts, charge control agent (Hodogaya Chemical Co., trade name Spiron Black TRH) 1 part, divinylbenzene 0.3 parts, Polymethacrylic acid ester macromonomer (Aa6, Tg = 9, manufactured by Toagosei Kagaku Kogyo Co., Ltd.)
(4 ° C.) 0.8 part, dipentaerythritol hexamyristate 10 parts and t-butylperoxy-2-ethylhexanoate 4 parts can be mixed with high shearing homomixer (TK type, manufactured by Tokushu Kika Co., Ltd. ), 12000 rpm
The mixture was stirred and mixed at the number of revolutions of 1, and uniformly dispersed to obtain a polymerizable monomer composition for core.

On the other hand, an aqueous solution prepared by dissolving 9.8 parts of magnesium chloride (water-soluble polyvalent metal salt) in 250 parts of ion-exchanged water and an aqueous solution prepared by dissolving 6.9 parts of sodium hydroxide in 50 parts of ion-exchanged water were stirred. The magnesium hydroxide colloidal dispersion liquid was prepared by slowly adding the mixture underneath. When the particle size distribution of the produced colloid was measured with a Microtrac particle size distribution measuring device (manufactured by Nikkiso Co., Ltd.), D50 (50% cumulative value of number particle size distribution) was 0.38 μm and D90
(90% cumulative value of number particle size distribution) was 0.84 μm. In the measurement by this Microtrac particle size distribution measuring device, the measurement range was 0.12 to 704 μm, the measurement time was 30 seconds, and ion-exchanged water was used as the medium.

To the magnesium hydroxide colloidal dispersion obtained above, 1 part of the polymerizable monomer composition for core and further sodium tetraborate decahydrate was added, and the mixture was stirred using a propeller stirrer. Stir-mix to obtain a composition dispersion, and then use a pump in a granulator (Clearmix CLM-0.8S: manufactured by M Technique Co., Ltd.) operating at a rotor rotation speed of 21,000 rpm, It was supplied and the droplets of the polymerizable monomer composition for core were granulated. This granulated composition aqueous dispersion was transferred to a reactor equipped with a stirring blade.
The composition aqueous dispersion was heated to initiate polymerization. At this time, the jacket temperature of the polymerization reactor and the temperature inside the polymerization reaction solution were measured so that the temperature of the aqueous dispersion was constant at 90 ° C., and the jacket temperature was controlled by a cascade control method or the like.

After confirming that the polymerization conversion rate reached almost 100%, 2 parts of methyl methacrylate was added, and further,
2,2'azobis (2-methyl-N- (2-hydroxyethyl) -propionamide) (trade name "VA-08
6 ": Wako Pure Chemical Industries, Ltd.) 0.2 part was dissolved in 100 parts of deionized water was added to the reaction vessel and polymerized to obtain an aqueous dispersion of polymer particles. Dehydrating the aqueous polymer particles,
The washing was repeated 3 times, followed by dehydration and drying to obtain core-shell type toner particles.

To 100 parts of the toner particles obtained above, 1 part of silica fine particles (A) having an average particle size of 12 nm and a hydrophobicity of 65% (trade name: RX200, manufactured by Nippon Aerosil Co., Ltd.)
Parts, average particle size 40 nm, silica fine particles (B) having a hydrophobicity of 64% (trade name: RX50, manufactured by Nippon Aerosil Co., Ltd.)
Toner (T1) was manufactured by adding 5 parts and organic fine particles having an average particle diameter of 0.38 μm and a sphericity of 1.13 synthesized in Reference Example 1 and mixing using a Henschel mixer.

The volume resistivity of the toner obtained by the above formulation was 11.5 (log (Ω · cm)). The volume average particle diameter (dv) of the toner is 6.9 μm,
The ratio of the volume average particle diameter to the number average particle diameter (dv / dp) is 1.
21 and the sphericity (Sc / Sr) of the value obtained by dividing the area (Sc) of the circle having the absolute maximum length of the toner as the diameter by the substantial projected area (Sr) of the particle is 1.1, and the boron content is Was 1.7 ppm.

Toner Production Example 2 Toner Production Example 1 was repeated except that sodium phosphate was added instead of sodium tetraborate decahydrate when the magnesium hydroxide colloidal dispersion was produced in Toner Production Example 1. A toner (T2) was manufactured in the same manner as in Example 1. The volume resistivity of the obtained toner was 11.6 (log (Ω · cm)). The volume average particle diameter (dv) of the toner is 7.1 μm, and the ratio of the volume average particle diameter to the number average particle diameter (dv / dp).
Is 1.24, and the sphericity (Sc / Sr) of the value obtained by dividing the area (Sc) of the circle whose diameter is the absolute maximum length of the toner by the substantial projected area (Sr) of the particle is 1.1, Phosphorus content was 1.9 ppm

(Toner Production Example 3) Toner (T3) was produced in the same manner as in Toner Production Example 1 except that sodium tetraborate decahydrate was not added. The volume resistivity of the obtained toner was 11.4 (log (Ω · cm)). Further, the volume average particle diameter (dv) of the toner is 7.2 μ.
m, the ratio of the volume average particle diameter to the number average particle diameter (dv / d
p) is 1.25, and the sphericity (Sc / Sr) of the value obtained by dividing the area (Sc) of the circle whose diameter is the absolute maximum length of the toner by the actual projected area (Sr) of the particles is 1.2. Yes, did not contain boron and phosphorus

(Toner Production Example 4) Toner (T4) was produced in the same manner as in Toner Granulation Example 1 except that dehydration and washing were performed only once in the post-treatment after polymerization. The volume resistivity of the obtained toner is 10.8 (log (Ω · c
m)). The volume average particle diameter (dv) of the toner is 6.9 μm, the ratio of the volume average particle diameter to the number average particle diameter (dv / dp) is 1.21, and the absolute maximum length of the toner is a circle. Area (Sc) divided by the substantial projected area (Sr) of the particles had a sphericity (Sc / Sr) of 1.1 and a boron content of 220 ppm.

Example 1 As shown in FIG. 3, a diameter of 10
A rubber elastic body 22 composed of a blended rubber of epichlorohydrin rubber and acrylonitrile-butadiene copolymer rubber is provided on the outer circumference of a stainless steel shaft 21 of mm,
It was formed by extrusion molding to have a thickness of 4.4 mm. After that, the outer peripheral surface of the rubber elastic body 22 was polished by a cylindrical cutting machine to make the surface roughness of the outer peripheral surface 4 μm in the axial direction and the circumferential direction.

Next, while rotating the rubber elastic body,
Ultraviolet rays were irradiated for 3 minutes using a W / cm lamp. The coefficient of friction of the surface of the rubber elastic body was 0.2. As shown in FIG. 2, the developing roll 8 was placed in contact with the photosensitive drum 1 so that the contact width was about 2 mm. As the photosensitive drum 1, an organic photosensitive drum is used,
The outer diameter was 30 mm.

The charging roll was manufactured as follows. 80 parts of epichlorohydrin copolymer rubber (A) consisting of 56 mol% of ethylene oxide, 40 mol% of epichlorohydrin and 4 mol% of allyl glycidyl ether,
Unsaturated rubber (B) 10 of acrylonitrile-butadiene copolymer rubber (NBR) having an acrylonitrile content of 33%
Parts and 10 parts of liquid unsaturated rubber (C) of liquid acrylonitrile-butadiene copolymer rubber (liquid NBR) having an acrylonitrile content of 33%, and further, sulfur 1.5
Part, tetramethylthiuram disulfide 1.5 parts, stearic acid 1 part, zinc oxide 5 parts, conductive carbon black 3 parts, calcium carbonate 20 parts and reaction product of diphenylamine and acetone (manufactured by Ouchi Shinko Co., Ltd., trade name " Nocrac B ") was added to prepare a rubber composition.

The above rubber composition was kneaded with a roll, then formed into a sheet and vulcanized at 155 ° C. for 30 minutes to obtain a vulcanized rubber sheet having a thickness of 2 mm. The hardness of the obtained vulcanized rubber sheet was measured and found to be 38. The charging roll is molded by using a roll-shaped base material (diameter: 0.
6 cm) as a core metal was placed in a roll mold, the rubber composition was put therein, and the core metal was shaped into a roll, and then vulcanized under the same conditions as described above. After vulcanization and molding, the surface of the obtained rubber roll was polished with an abrasive, and the surface roughness was 6
It was made to be μm. At this time, the length of the rubber roll was 23 cm, and the diameter of the roll including the core metal was 1.2 cm.

80% of a polyurethane resin aqueous dispersion having a glass transition temperature of 72 ° C. (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., trade name: “Superflex 126 (solid content 20%)”) and 20% tin oxide were placed in a ball mill pot. Put in and disperse well.
After immersing the rubber roll in this dispersion and pulling it up,
Heat treatment was performed at 150 ° C. for 10 minutes. The finished roll had a polyurethane resin layer thickness of 30 μm and a surface roughness of 3 μm. This was used as the charging roll 3.

As the exposure device 4, a combination of a laser device and an optical system was used. As the supply roll 9, a sponge roll made of urethane rubber having an outer diameter of 13 mm was used. The supply roll 9 was brought into contact with the developing roll 7 so that the contact width was about 2 mm.

The layer thickness regulating blade 8 is made of a urethane rubber elastic body, has a compression set of 6%, a Young's modulus of 850 g / mm 2, and a repulsion elastic modulus of 30%.
Then, 12 mm (free end length) x 215 mm (width) x 1.3
A flat blade having a thickness of mm (mm) was used. As shown in FIG. 4 (b), when this blade was attached to the developing roll 7 so that the bending amount δ was 4.0 mm, the linear pressure f against the developing roll was about 1.08 g / mm, and the contact angle was θ was 80.7 degrees. The electric resistance of the blade was 5 × 10 5 Ω.

Toner 1 accommodated in the developing device 11
As 0, continuous printing was carried out using the toner T1 obtained in Toner Production Example 1, and the image resolution, paper fog and filming were evaluated. The evaluation results are shown in Table 1.

Examples 2 to 4 and Comparative Examples 1 to 4 Table 1 shows the surface roughness of the charging roll before coating with the polyurethane resin, the glass transition temperature of the polyurethane resin to be coated, and the toner used for development. Evaluation was performed in the same manner as in Example 1 except that The evaluation results are shown in Table 1.

[0147]

[Table 1]

The following can be seen from Table 1. In the image forming method of Comparative Example 1 in which the glass transition temperature of the polyurethane resin to be coated is lower than the range specified in the present invention, paper fog is likely to occur in both the H / H environment and the L / L environment, and the charging roll is also easily soiled. Comparative Example 2 in which the surface roughness before coating with the polyurethane resin is larger than the range specified in the present invention
In the image forming method of (3), paper fogging easily occurs in both the H / H environment and the L / L environment, and the charging roll is easily soiled.
In the image forming method of Comparative Example 3 in which the toner does not contain a specific amount of boron or phosphorus specified in the present invention, paper fogging easily occurs in the H / H environment. In the image forming method of Comparative Example 4 in which the toner contains a larger amount of boron than the range specified in the present invention, paper fog is likely to occur in the H / H environment, and the charging roll is easily soiled.

On the other hand, in the image forming methods of Examples 1 and 2 of the present invention, it is found that paper fogging is unlikely to occur and the charging roll is not easily soiled even in a severe environment such as high temperature and high humidity and low temperature and low humidity. .

[0150]

According to the present invention, the photosensitive member can be uniformly charged, the toner can be uniformly and thinly attached to the outer peripheral surface of the developing roll, and the toner can be formed on the surface of the photosensitive drum. Further, since the toner can be moved accurately in accordance with the pattern of the electrostatic latent image, it can be seen that paper fogging is unlikely to occur and the charging roll is not easily soiled even in a severe environment such as high temperature and high humidity and low temperature and low humidity.

[Brief description of drawings]

FIG. 1 is a diagram showing a method of measuring a friction coefficient.

FIG. 2 is a schematic diagram of an image forming apparatus according to an embodiment of the present invention.

3 is a partially cutaway perspective view of the developing roller shown in FIG.

4 (a) is a schematic view showing the positional relationship between the layer thickness regulating blade and the developing roll shown in FIG. 2, and FIG. 4 (b) is a main part schematic view for explaining the amount of bending.

FIG. 5 is a schematic diagram of a tandem type color image forming apparatus according to an embodiment of the present invention.

[Explanation of symbols]

1 ... Photosensitive drum 2..Cleaning device 3 ... Charging roll 4 ... Laser light irradiation device 5 ... Transfer roll 7 ... Development roll 8 ... Layer thickness control blade 9 ... Supply roll 10 ... Toner 11..Developing device 13 ... Heating roll 14 ... Pressure roll 15 ... Conveyor belt 40 ... Measurement paper 42 ... 44 ... Tension gauge 50 ... Holder 71..Conductive shaft 72..Rubber elastic body

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2H005 AB06                 2H030 AB02 AD01 AD02 BB02 BB21                       BB42                 2H200 FA16 GA12 GA34 GA44 GA47                       GB12 GB13 GB15 GB25 HA02                       HB12 HB43 HB45 HB47 JA02                       JB06 JB10 JC03 LA12 MA01                       MA03 MA04 MA20 MC18 MC20

Claims (3)

[Claims] 1. A developing method, wherein an electrostatic latent image is formed on the surface of a latent image carrier uniformly charged by a charging roll, and the electrostatic latent image is developed into a toner image with toner. , The charging roll covers a metal core material with a rubber layer having a surface roughness of 0.5 to 10 μm, and the rubber layer has a glass transition temperature of 3
A developing method comprising a polyurethane resin coating layer at 0 to 80 ° C., wherein the total content of boron or phosphorus in the toner is 0.1 to 100 ppm. 2. An image forming method in which a toner image obtained by the developing method according to claim 1 is transferred onto a transfer material and then fixed. 3. The image forming method according to claim 2, wherein:
A color image forming method using four toners of yellow, magenta, cyan and black as toners.