JP3109944B2 - Electrostatic image developing toner and image forming method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner used in electrophotography, electrostatic recording, and the like, and an image forming method using the toner.

[0002]

2. Description of the Related Art Conventionally, electrophotography has been disclosed in U.S. Pat. No. 2,297,691, Japanese Patent Publication No. 42-23910.
Many methods are known, as described in Japanese Patent Publication No. JP-B-43-24748 and Japanese Patent Publication No. 43-24748. Generally, a photoconductive substance is used to form an electric latent image on a photoreceptor by various means, and then the latent image is developed using toner, and if necessary, a toner image is transferred onto a transfer material such as paper. Is transferred and then fixed by various methods to obtain a copy. As a fixing method, a pressure fixing method of passing between two or more metal rolls, an oven fixing method of passing through a heating atmosphere by an electric heater, and a hot roll fixing method of passing between heating rollers or a surfing method, which is currently most common, are used. There is a fixing method.

In the pressure heating method using a heating roller, fixing is performed by allowing the toner image surface of a sheet to be fixed to pass through the surface of a heat roller having a surface formed of a material having a releasable property with respect to the toner while contacting the surface under pressure. Things. In this method, since the surface of the heat roller and the toner image of the sheet to be fixed come into contact with each other under pressure, the thermal efficiency at the time of fusing the toner image onto the sheet to be fixed is extremely good, and the fixing is performed quickly. And is very effective in high-speed electrophotographic copying machines. In the above method, since the surface of the heat roller and the toner image are in contact with each other under pressure in a molten state, a part of the toner image adheres to the surface of the fixing roller and is transferred, and is transferred again to the next sheet to be fixed. A so-called offset phenomenon occurs, and the sheet to be fixed may be stained. Preventing toner from adhering to the surface of the heat fixing roller is one of the essential conditions of the heat roller fixing method.

In this hot roll fixing method, a relatively long time is required from when the power of the heat source is turned on to when the temperature of the hot roll rises to a temperature at which the heat roll can be fixed and the heat roll becomes fixable. Therefore, the time required for hard copy output in office work is not short. This weight-up time results in a loss of time and hinders efficient office work. With the shortening of the wait-up time and the speeding up of the recording method by electrophotography, various devices have been devised to improve the fixability of the hot roll fixing system. In order to improve the fixability of the toner, it is necessary to reduce the viscosity of the toner at the time of melting and increase the adhesion area with the fixing base material in order to improve the fixing property of the toner. For this reason, the glass transition point (Tg) of the binder resin used for this purpose is required. ) And low molecular weight.

However, the T of the binder resin is easily obtained.
When the g and the molecular weight are reduced, the above-mentioned offset is likely to occur.

As described above, since low-temperature fixing properties and anti-offset properties are contradictory, it is difficult to develop a toner that satisfies these requirements simultaneously.

As binder resins satisfying these requirements, Japanese Patent Publication No. 63-32182 and Japanese Patent Publication No. 63-32
No. 382 proposes a binder resin having two peaks in gel permeation chromatography (GPC). This binder is an excellent binder resin that improves fixability at low molecular weight components and improves anti-offset properties at high molecular weight components. There is a problem that the performance is reduced and the volatile component in the toner is increased. Therefore, there is a demand for a toner and a hot roll fixing system with further improved fixability.

In recent years, the recording method using the electrophotographic method has been applied to a wide range of applications, and has been used in general offices and homes. When the amount of the residual monomer and the residual solvent in the toner is large, there is a problem that an odor is generated at the time of image formation or fixing and the discomfort is caused, and a toner in which the residual monomer and the residual solvent are reduced is demanded.

In particular, in recent electrophotographic apparatuses, contact charging means is used instead of corona charging in order to prevent generation of ozone due to application of a high voltage when forming an electrostatic latent image on the surface of a photoreceptor. . In an electrophotographic apparatus using this contact charging means, generation of ozone was almost eliminated, and as a result, it became possible to not attach an ozone filter. When the ozone filter is not installed, the problem of toner odor is liable to occur remarkably.

In order to reduce the amount of the residual monomer in the toner, a method of increasing the amount of the polymerization initiator of the binder resin,
When a solvent is distilled after the polymerization, a method in which distillation is performed under reduced pressure for an extremely long time, and a method in which a toner is kneaded at a high temperature while reducing the pressure in manufacturing the toner, may be used. However, there are some problems when trying to reduce the amount of residual monomers by these methods. For example, simply increasing the amount of the polymerization initiator makes it difficult to control the molecular weight of the polymer, increases the low molecular weight component, broadens the peak shape of the molecular weight distribution, and may deteriorate the developing characteristics. In addition, the method of vacuum distillation of the solvent after polymerization has problems such as occupying a long period of production equipment, consuming a large amount of heat and wasting energy, and the molecular weight of the resin due to depolymerization (polymer decomposition). May decrease. The method in which the toner is depressurized during production and kneaded at a high temperature has a problem that the high-temperature kneading tends to cause an adverse effect such that the dispersibility of another material of the toner, for example, wax is deteriorated.

Conventionally, a corona discharger has been known as a charging means in an electrophotographic apparatus or the like. However, corona dischargers have problems such as the need to apply a high voltage and the generation of a large amount of ozone.

Therefore, recently, the use of contact charging means without using a corona discharger has been studied. Specifically, a voltage is applied to a conductive roller or a conductive blade serving as a charging member, and the roller or the blade is brought into contact with a photosensitive member serving as a charged member to charge the surface of the photosensitive member to a predetermined potential. If such a contact charging means is used, the voltage can be reduced as compared with a corona discharger, and the amount of generated ozone can be reduced.

Further, in an image forming apparatus including a step of electrostatically transferring a toner image formed on a surface of a latent image carrier (photoreceptor) to a sheet-like transfer material such as paper, the image forming apparatus includes:
Using a latent image carrier such as an endless belt, a transfer device to which a bias is applied is pressed against this, and the transfer material is passed between the two to transfer the toner image on the latent image carrier side to the transfer material. Japanese Patent Application Laid-Open No. Sho 59-46, for example,
No. 664.

Such an apparatus adjusts the pressing force of the transfer roller against the latent image carrier by adjusting the pressing force of the transfer roller against the latent image carrier, as compared with a transfer means using corona discharge which has been widely used in the past. Since the adsorption area to the body can be enlarged, the transfer material is positively supported at the transfer site. For this reason, there is little possibility that a transfer error due to a synchronization failure due to the transfer material conveying means, a loop existing in the transfer material, a curl, etc. occurs, and the transfer material conveyance path is shortened due to the recent miniaturization of this type of image forming apparatus. It is easy to cope with a request for reducing the diameter of the latent image carrier.

However, when the above-mentioned contact charging means is used, there is a problem that insufficient charging occurs if sufficient contact with the member to be charged cannot be maintained. In the contact portion, when the developer component remains on the photoreceptor surface, the developer component remaining on the charging member and the photoreceptor surface because the charging member has a predetermined contact pressure. Has a problem that the latent image is fixed and affects the formation of a latent image or a developed image.

In an apparatus for performing transfer by contact proposed in Japanese Patent Application Laid-Open No. Sho 59-46664, a certain amount of pressure needs to be applied to the transfer apparatus because a transfer current is supplied by a contact portion. . When the contact pressure is applied, pressure is applied to the toner image on the latent image carrier, and aggregation tends to occur.

Further, when the surface of the latent image carrier is made of resin, adhesion occurs between the toner aggregate and the latent image carrier, and as a result, the toner is transferred to the surface of the latent image carrier or transferred. The phenomenon of sticking to the surface of the contact member of the device may occur.

When such a phenomenon occurs, the latent image formation of the latent image carrier may be lost, or the transfer may be omitted.
There may be a problem that a defective toner image is generated.

[0019]

SUMMARY OF THE INVENTION An object of the present invention is to provide a toner for developing an electrostatic image and an image forming method which solve the above-mentioned problems.

It is an object of the present invention to exhibit excellent low-temperature fixability and offset prevention properties and excellent development characteristics.
An object of the present invention is to provide a toner for developing an electrostatic charge image, which has a small amount of volatile components such as residual monomers in the toner and generates little odor.

Another object of the present invention is to provide an image forming method using a fixing system based on an excellent hot-roll fixing system, which is capable of shortening the wait-up time and speeding up the electrophotographic process.

An object of the present invention is to provide a toner for developing an electrostatic charge image which has a small amount of volatile components such as a residual monomer, a decomposition product of a monomer, a by-product, and a residual solvent in the toner and has a small odor.

It is a further object of the present invention to provide an image forming method which suppresses odors such as ozone odor and toner odor.

Further, an object of the present invention is to provide an image forming method using a contact charging means and a means for performing transfer by abutting a transfer roller without developing agent components sticking to the surface of the charging member and the photosensitive member. An object of the present invention is to provide an electrostatic image developing toner capable of supplying a high quality toner image for a long time or over a large number of sheets.

[0025]

According to the present invention, a charging member to which a voltage is applied is brought into contact with an electrostatic latent image carrier,
Charging the electrostatic latent image carrier, forming an electrostatic latent image by exposure, and developing the electrostatic latent image with toner, applying a voltage to the toner image formed on the electrostatic latent image carrier. Transferring the toner image onto the transfer material while pressing the transfer material with the transfer member to which the toner image is applied, and heating and pressing and fixing the transferred toner image. The toner contains a styrenic resin polymerized in the presence of a trifunctional or higher polyfunctional polymerization initiator, and has a molecular weight distribution of 3.5 × 10 ^{3 to} 5 ×
It has a maximum value (P ₁ ) in the region of 10 ⁴ , and has a molecular weight of 1 × 10 ⁵
Having a maximum value (P ₂ ) or a shoulder in the above region,
It contains 15% or less of a resin component in a region having a molecular weight of 3 × 10 ³ or less, and contains 5 to 5 resin components in a region having a molecular weight of 1 × 10 ⁵ or more.
The present invention relates to a toner for developing an electrostatic image, wherein the toner contains 0% and the content of styrene and benzaldehyde in the toner is 100 ppm or less.

Further, according to the present invention, a charging member to which a voltage is applied is brought into contact with the electrostatic latent image carrier to charge the electrostatic latent image carrier, and the charged electrostatic latent image carrier is exposed. To form an electrostatic latent image, the formed electrostatic latent image contains a styrene-based resin polymerized in the presence of a trifunctional or higher polyfunctional polymerization initiator,
In the molecular weight distribution by GPC, the molecular weight was 3.5 × 1.
A region having a maximum value (P ₁ ) in a region of 0 ^{3 to} 5 × 10 ^4, a region having a maximum value (P ₂ ) or a shoulder in a region having a molecular weight of 1 × 10 ⁵ or more, and a region having a molecular weight of 3 × 10 ³ or less. 15 resin components
% Of a resin component having a molecular weight of 1 × 10 ⁵ or more, and ⁵ to 50% of a resin component, and a toner for developing an electrostatic charge image having a styrene and benzaldehyde content of 100 ppm or less. Forming a toner image,
The formed toner image is transferred to the transfer material while pressing the transfer material with a transfer member to which a voltage is applied, and the toner image on the transfer material is heated and pressed by a heat roller having a core metal thickness of 1 mm or less. Image forming method.

The present invention will be described in more detail.

The binder resin in the toner of the present invention is GP
In the molecular weight distribution at C, the molecular weight was 3.5 × 10 ^3.
It has a maximum value in the region of 〜5 × 10 ⁴ and a molecular weight of 1 × 10 ⁵
It is characterized by having a maximum value or a shoulder in the above region. In the present invention, the shoulder is a point at which the differential value of the GPC chromatogram curve becomes an extreme value.

By having a maximum value in the molecular weight region of 3.5 × 10 ^{3 to} 5 × 10 ⁴ , a toner having good fixability can be obtained, and good pulverizability can be obtained in the pulverization step in the production of the toner. By having a maximum value or a shoulder in a region having a molecular weight of 1 × 10 ⁵ or more, good offset prevention properties can be obtained.

The resin component having a maximum value or a shoulder in the region having a molecular weight of 1 × 10 ⁵ or more has a higher anti-offset property as its content increases, but may impair the fixing performance if it is too much. In the molecular weight distribution by GPC,
The component having a molecular weight of 100,000 or more is 5 to 50% by weight, preferably 10 to 50% by weight. If the amount is less than 5% by weight, good offset prevention properties may not be obtained, and it is difficult to easily prevent toner from flowing out of the cleaning member provided in the fixing device. On the other hand, when it exceeds 50% by weight, the tendency to inhibit the fixing property becomes high. In order to improve the anti-offset property while maintaining the fixing property, it is preferable to bring the maximum value or the shoulder in the molecular weight distribution to the high molecular weight region to make the molecular weight higher.

In order to obtain these high molecular weight resin components, polymerization is carried out in the presence of a polyfunctional polymerization initiator. As the polyfunctional polymerization initiator, a polymerization initiator having three or more functional groups generating radicals is used, and a tetrafunctional polymerization initiator or a polyfunctional polymerization initiator having four or more functional groups is more preferable. According to the study of the present inventors, at the time of toner production, since the internal friction is very strong at the time of melt-kneading, a large shearing force is applied to the polymer, cutting of the high molecular weight component occurs, and the high molecular weight component The molecular weight tends to decrease overall. That is, the molecular weight distribution of the binder resin in the toner tends to have a lower molecular weight than the molecular weight distribution of the toner raw material resin, and therefore, the molecular weight distribution of the toner raw material resin does not completely match the offset prevention property of the toner. .

According to the study of the present inventors, when the number of functional groups in the polyfunctional polymerization initiator is increased, the molecular weight distribution of the raw material resin can be shifted to the higher molecular weight side, and at the time of melt-kneading during the production of the toner. Molecular shearing of the high molecular weight resin component is unlikely to occur, and it is difficult to generate a component having a molecular weight of 3 × 10 ³ or less. Therefore, the toner using the raw material resin produced by using the polymerization initiator having a small number of functional groups is more excellent in the anti-offset property than the toner using the resin. Further, when a polyfunctional polymerization initiator having a large number of functional groups is used, the amount of monomers remaining in the raw material resin can be reduced.

In the molecular weight distribution by GPC, it is preferable to have a maximum value in a region of molecular weight of 3.5 × 10 ^{3 to} 5 × 10 ⁴ from the viewpoint of the fixing property of the toner and the pulverizability in the pulverization step in producing the toner. As the position of the maximum value in the molecular weight distribution becomes lower, the lower temperature fixing becomes possible. Considering blocking resistance, the molecular weight is 5 × 10
It is more preferable to have a local maximum in the region of ^{3 to} 5 × 10 ⁴ . A low molecular weight component having a molecular weight of less than 5 × 10 ³ tends to have an adverse effect on development characteristics and the like. The position of the maximum value is molecular weight 5 × 1
It becomes less than 0 ^3, when these low molecular weight fraction is increased, or inhibit the offset preventing properties, or blocking occurs and toner adhesion may be generated with respect to the drum surface, further, to generate fusion inside the toner production apparatus Sometimes.
Further, the toner may adhere to the toner carrier (developing sleeve) or the frictional charge applying member (application blade or application roller), thereby reducing the frictional charge application ability and deteriorating the development characteristics. When the position of the local maximum value on the low molecular weight side exceeds the molecular weight of 5 × 10 ⁴ , the fixability becomes poor.

A component having a molecular weight of 5 × 10 ⁴ or less acts on fixability, and the component has a molecular weight distribution of 30 to 95% by weight.
And more preferably 40 to 90% by weight. If the amount is less than 30% by weight, it is difficult to obtain good fixability, and the pulverizability in the pulverization step at the time of toner production becomes poor. On the other hand, if it exceeds 95% by weight, it is difficult to obtain sufficient offset prevention properties.

From the low-temperature fixing property, the molecular weight is 3.5 × 10 ^3-
Since the content of the low molecular weight resin component having a maximum value in the region of 5 × 10 ⁴ becomes large, the amount of the residual monomer and the amount of the residual by-product at the time of synthesizing the resin component are determined by the amount of the residual monomer and the amount of the residual by-product of the entire resin. Have a significant effect.

In order to reduce the residual monomers in the toner by simply reducing the residual monomers in the low molecular weight resin component by increasing the amount of the polymerization initiator and manufacturing conditions, the molecular weight distribution of the low molecular weight component becomes broad. In addition, the amount of the component having a molecular weight of 3 × 10 ³ or less corresponding to the base of the low molecular weight component peak is increased, and the charge amount of the toner is apt to be reduced, which causes a decrease in image density.

The component having a molecular weight of 3 × 10 ³ or less preferably accounts for 15% or less of the total amount of the binder resin. If it exceeds 15%, the image density will decrease. It is more preferably at most 13%. More preferably, it is 10% or less.

Further, in the molecular weight distribution by GPC, a low molecular weight resin component having a maximum value in a region of a molecular weight of 3.5 × 10 ^{3 to} 5 × 10 ⁴ comprises at least a polymerization initiator A having a long half life and a half life of a polymerization initiator A. The short polymerization initiator B is polymerized in the presence of two different polymerization initiators, and these polymerization initiators have a ratio of the half life τ _A to the half life τ _{B at} the polymerization temperature (τ
It has been found that a toner for developing an electrostatic image containing a resin component synthesized under the condition that ( _A / τ _B ) is 1.5 or more is more preferable for solving the above-mentioned problems.

The present inventors have conducted intensive studies and found that a preferred method for synthesizing a low-molecular-weight resin component having a maximum value in a region of a molecular weight of 3.5 × 10 ^{3 to} 5 × 10 ⁴ is as follows.
At least two kinds of polymerization initiators having a long half life of polymerization initiator A and a short half life of polymerization initiator B are used, and the ratio τ _A / τ _B of the half life τ _A and the half life τ _{B at} the polymerization temperature is obtained. When it is 1.5 or more, the low molecular weight side of the maximum value in the molecular weight distribution becomes a sharp peak, and the molecular weight is 3 × 1
0 ³ The following ingredients are likely to prepare a resin component of 15% or less. As a result, the toner can have sufficient developing characteristics and fixing characteristics, can reduce the residual monomer, and can obtain a toner with less odor.

More preferably, the polymerization temperature when polymerizing the low molecular weight resin component is in the range of 75 to 145 ° C., and the half life τ _{B at} the polymerization temperature of the polymerization initiator B having a short half life is 0.1.
The time is preferably 1 hour or more, and more preferably 0.5 to 10 hours.

The half-life τ _A and the half-life τ of the polymerization initiator A having a long half-life and the polymerization initiator B having a short half-life at the polymerization temperature.
The ratio τ _A / τ _B of _B, more preferably 2 to 5 × 10
A range of ³ is good.

More preferably, the polymerization temperature when polymerizing the low molecular weight resin component is in the range of 75 to 145 ° C., and the half life τ _B of the polymerization initiator B having a short half life at the polymerization temperature is 0.5 to 3 may be a time may be half-life tau _a long polymerization initiator a having a half-life of 2 to 60 hours, the ratio tau _a / tau _B of half-life tau _B and half-life tau _a is 2 A combination of the polymerization initiator A and the polymerization initiator B in a range of from 5 to 10 ² is preferable.

A combination of polymerization initiators satisfying the above conditions can be preferably used in the present invention. Polymerization initiator A
The addition amount and the addition ratio of the polymerization initiator B are selected depending on the molecular weight distribution of the obtained low molecular weight resin component, the type of the monomer, the production conditions, and the like. The amount of the polymerization initiator A and the polymerization initiator B to be added is 100 weight parts of a polymerizable monomer necessary for synthesizing a low molecular weight resin component having a maximum value in a region of a molecular weight of 3.5 × 10 ^{3 to} 5 × 10 ^4. Parts by weight of the polymerization initiator is used in the range of 0.1 to 5 parts by weight, and the ratio of the polymerization initiator A / the polymerization initiator B is 0.01 to 10 parts by weight.
It is used in the range of 0, more preferably 0.1 to 10.

It is preferable to prepare a low molecular weight resin component (ie, a low molecular weight vinyl resin) using a polymerizable vinyl monomer as the polymerizable monomer. As the vinyl resin, a styrene resin is preferable. Furthermore, styrene homopolymer, styrene-
Acrylic acid ester copolymers and styrene-methacrylic acid ester copolymers are preferred.

When these methods are used, the residual monomer in the toner is reduced favorably. In the present invention, the styrene monomer and benzaldehyde are contained in the toner at 100 pp.
m. Benzaldehyde is
Since it has a characteristic strong odor, it is more preferably at most 10 ppm. The styrene monomer is 50pp
m is more preferable. Further, when an acrylic monomer is used as a comonomer, the content of the acrylic monomer is more preferably 30 ppm or less.

By reducing the residual monomer and benzaldehyde, not only the odor generated at the time of copying is suppressed, but also the toner particles are hardly fixed to the drum, and a phenomenon called filming fusion occurs. It becomes difficult. In the case of a contact charging system device and a contact transfer system device, the filming or fusing is particularly likely to occur, but these phenomena tend to be less likely to occur by reducing residual monomers and benzaldehyde in the toner.

The present inventors have further found that the reduction of the residual monomer reduces the adhesion of the toner particles and silica to the transfer roller, and also reduces the free silica accumulated on the developing device stay.

Although the reason is not clear, it is considered that the residual monomer contributes to liberation of the silica and toner particles, and it is considered that the residual monomer is reduced and the liberation of silica is also reduced.

The remaining monomers and benzaldehyde in the toner are quantified by using a gas chromatograph, for example, by the following method.

Using 2.55 mg of N, N-dimethylformamide (DMF) as an internal standard, 100 ml of acetone is added to prepare a solvent containing an internal standard. Next, the toner 40
0 mg is made into a 10 ml solution with the above solvent. After 30 minutes on an ultrasonic shaker, leave for 1 hour. Then 0.5
Filter through a μm filter. The amount of implanted sample is 4μ
l.

The conditions of the gas chromatogram are shown below.・ Capillary column @ J & W Scientific 3
0m × 0.249mm, DBWAX, 0.25μ thickness
m｝ ・ Detector FID, nitrogen pressure 0.45 kg / cm ²・ Injection temperature 200 ° C, detector temperature 2
The temperature was set to 00 ° C., and the column temperature was raised from 50 ° C. at a rate of 5 ° C./1 minute for 30 minutes. Preparation of a calibration curve A gas chromatographic measurement is similarly performed on a standard sample in which the target monomer is added to the same amount of the DMF and acetone solution as the sample solution, and the weight ratio / area ratio of the monomer and the internal standard DMF is determined.

Further, it can be determined in the same manner as above, using toluene as an internal standard and tetrahydrofuran as a solvent.

As the polymerization initiator used in the present invention, an oil-soluble initiator is used. Representative examples include, for example, acetylcyclohexylsulfonyl peroxide, isobutyryl peroxide, diisopropyl peroxydicarbonate, 2-ethyl exyl peroxydicarbonate, 2,4-dichlorobenzoyl peroxide, t-butylperoxy Pivalate, 3,5,5
-Trimethylhexanyl peroxide, octanoyl peroxide, decanoyl peroxide, lauroyl peroxide, stearoyl peroxide, propionyl peroxide, succinic acid peroxide, acetyl peroxide, t-butylperoxy-2-ethylhexano Ethate, benzoyl peroxide, parachlorobenzoyl peroxide, t-butylperoxyisobutyrate, t-butylperoxymaleic acid, t-butylperoxylaurate, cyclohexanone peroxide, t-butylperoxyisopropyl carbonate, 2,5-dimethyl-
2,5-dibenzoylperoxyhexane, t-butylperoxyacetate, t-butylperoxybenzoate, diisobutyldiperoxyphthalate, methyl ethyl ketone peroxide, dicumyl peroxide,
2,5-dimethyl-2,5-di-t-butylperoxyhexane, t-butylcumyl peroxide, t-butylhydroperoxide, di-t-butylperoxide,
2,5-dimethyl-2,5-di-tert-butylperoxyhexane, diisopropylbenzene hydroperoxide, paramenthane hydroperoxide, pinane hydroperoxide, 2,5-dimethylhexane-2,5-
Peroxide initiators such as dihydroperoxide and cumene hydroperoxide, 2,2'-azobisisobutyronitrile, 1,1'-azobiscyclohexane 1
-Carbonitrile, 2,2'-azobis-4-methoxy-
Azo initiators such as 2,4-dimethylvaleronitrile and 2,2'-azobis-2,4-dimethylvaleronitrile are exemplified. These may be used alone, in combination, or, if necessary, in combination with a polyfunctional radical polymerization initiator.

In order to polymerize the high molecular weight styrene resin component in the present invention, it is preferable to use a polyfunctional polymerization initiator.

By using a polyfunctional polymerization initiator, the styrene resin has a higher molecular weight, whereby sufficient offset prevention can be obtained. Examples of the polyfunctional polymerization initiator used in the present invention include trifunctional radical polymerization initiators such as tris (t-butylperoxy) triazine and vinyltris (t-butylperoxy) silane.
2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane, a copolymerized compound of t-butylperoxyallyl carbonate (for example, Hyper B and Hyper G series manufactured by NOF Corporation), t- Examples thereof include a polyfunctional radical polymerization initiator having four or more functional groups such as a copolymerized compound of butylperoxymaleic acid.

These polyfunctional polymerization initiators may be used alone, in combination, or, if necessary, in combination with a monofunctional polymerization initiator. The amount of the polyfunctional polymerization initiator to be used is 0.01 to 10% with respect to the amount of the monomer constituting the high-molecular-weight styrene resin component which forms a local maximum or a shoulder in a region of 1 × 10 ⁵ or more.
It is good to use 5% by weight, preferably 0.05 to 3% by weight.

In the present invention, the molecular weight of the peak or / and the shoulder of the chromatograph by GPC is measured under the following conditions.

The column was stabilized in a heat chamber at 40 ° C., and TH was used as a solvent at this temperature.
F at a flow rate of 1 ml / min.
50% of a THF sample solution of the resin adjusted to 0.1% by weight.
Measure by injecting ~ 200 μl. In measuring the molecular weight of a sample, the molecular weight distribution of the sample is calculated from the relationship between the logarithmic value of a calibration curve prepared from several types of monodisperse polystyrene standard samples and the count number. As a standard polystyrene sample for preparing a calibration curve, for example, Pressrue
Chemical Co. Or Toyo Soda Kogyo Co., Ltd. has a molecular weight of 6 × 10 ² , 2.1 × 10 ³ , 4 × 10 ³ ,
1.75 × 10 ⁴ , 5.1 × 10 ⁴ , 1.1 × 10 ⁵ ,
3.9 × 10 ⁵ , 8.6 × 10 ⁵ , 2 × 10 ⁶ , 4.4
It is applicable to use a sample of 8 × 10 ⁶ and use at least about 10 standard polystyrene samples. An RI (refractive index) detector is used as the detector.

In order to accurately measure the molecular weight region of 10 ³ to 4 × 10 ^6, a plurality of commercially available polystyrene gel columns may be used in combination.
rs Inc. of μ-styragel 500,10 ^3, 1
0 ⁴ , 10 ⁵ , Showa Denko Sho
dex KF-80M, KF-802, 803, 80
4,805 combinations or TSKge manufactured by Toyo Soda
l G1000H, G2000H, G2500H, G3
000H, G4000H, G5000H, G6000
A combination of H, G7000H and GMH is preferred.

In the present invention, the weight percentage of each component relative to the binder resin is determined, for example, as follows.

The weight% of the component having a molecular weight of 3 × 10 ³ or less with respect to the binder resin is calculated based on the area represented by the component having a molecular weight of 4 × 10 ^{2 to} 3 × 10 ^{3 in} the chromatogram by GPC and the component having a molecular weight of 4 × 10 ² or more. It is calculated from the area ratio with the area indicated by. When the THF-insoluble component is present, the weight percent of the THF-soluble component is separately obtained, and the obtained value is calculated from the chromatogram by GPC in the same manner as described above. ^Two
The weight% of the components of ³ to 10 ³ is calculated and set as the weight% of the components of 3 × 10 ³ or less.

Specific Example 1 of Chromatogram by GPC
These are shown in FIG.

In the present invention, a styrene polymer or a styrene copolymer is preferably used as the high molecular weight styrene resin component.

The styrene monomer used includes, for example, styrene; o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene,
-Phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-n-butylstyrene, p-tert-butylstyrene, p-n-hexylstyrene, p- Styrene derivatives such as n-octylstyrene, pn-nonylstyrene, pn-decylstyrene and pn-dodecylstyrene can be used.

Examples of comonomers for obtaining a styrene copolymer include ethylenically unsaturated monoolefins such as ethylene, propylene, butylene and isobutylene; unsaturated polyenes such as butadiene; vinyl chloride, vinylidene chloride, vinyl bromide, and the like. Vinyl halides such as vinyl fluoride; vinyl esters such as vinyl acetate, vinyl propionate and vinyl benzoate; methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, methacrylic acid n
-Octyl, dodecyl methacrylate, methacrylic acid-2
Α-methylene aliphatic monocarboxylic esters such as ethylhexyl, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate; methyl acrylate, ethyl acrylate, n-butyl acrylate, acrylic acid Acrylic esters such as isobutyl, propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate and phenyl acrylate;
Vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl isobutyl ether; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and methyl isopropenyl ketone; N-vinyl pyrrole, N-vinyl carbazole, N-vinyl indole,
N-vinyl compounds such as N-vinylpyrrolidone; vinyl naphthalenes; acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, and acrylamide; esters of the aforementioned α, β-unsaturated acids and diesters of dibasic acids; Are used alone or in combination of two or more.

The binder resin used in the present invention may be, if necessary, a polymer cross-linked with a cross-linkable monomer as exemplified below.

Aromatic divinyl compounds, for example, divinylbenzene, divinylnaphthalene, etc .: diacrylate compounds linked by an alkyl chain, for example, ethylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1,4-butanediol Diacrylate,
1,5-pentanediol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, and those obtained by replacing the acrylate of the above compounds with methacrylate; diacrylate linked by an alkyl chain containing an ether bond Compounds such as diethylene glycol diacrylate, triethylene glycol diacrylate, tetratoethylene glycol diacrylate, polyethylene glycol # 400 diacrylate, polyethylene glycol # 600 diacrylate, dipropylene glycol diacrylate, and methacrylates of the above compounds Diacrylate compounds linked by a chain containing an aromatic group and an ether bond, for example, polyoxyethylene (2) -2,2-bi (4-hydroxyphenyl) propane diacrylate, polyoxyethylene (4) -2,
2-bis (4-hydroxyphenyl) propane diacrylate and those obtained by replacing the acrylate of the above compound with methacrylate; further, polyester type diacrylate compounds, for example, listed under the trade name MANDA (Nippon Kayaku) Can be Examples of polyfunctional crosslinking agents include pentaerythritol triacrylate, trimethylolethane triacrylate, trimethylolpropane triacrylate, tetramethylol methanetetraacrylate,
Oligoester acrylates and those obtained by replacing the acrylates of the above compounds with methacrylates; triallyl cyanurate, triallyl trimellitate; and the like.

These cross-linking agents can be used in combination with other monomer components 10
0.01 to 5 parts by weight (more preferably 0.03 to 3 parts by weight) can be used with respect to 0 parts by weight.

In the present invention, a high molecular weight styrenic resin polymerized using a polyfunctional polymerization initiator and a molecular weight of 3.5
The mixing weight ratio with the low molecular weight resin component having a maximum value in the region of × 10 ^{3 to} 5 × 10 ⁴ is preferably 10 to 70:90 to 30 (preferably 20 to 60:80 to 40).

In the toner using the resin according to the present invention, in addition to the above-mentioned binder resin component, the content of the binder resin component in a proportion smaller than the content of the binder resin is as follows as long as the effect of the present invention is not adversely affected. A compound may be contained.

For example, silicone resin, polyester resin, polyurethane, polyamide, epoxy resin, polyvinyl butyral, rosin, modified rosin, terpene resin,
Examples include aliphatic or alicyclic hydrocarbon resins such as phenolic resins, low molecular weight polyethylene or low molecular weight polypropylene, aromatic petroleum resins, chlorinated paraffins, paraffin wax and the like.

As a method for synthesizing the binder resin according to the present invention, a bulk polymerization method, a solution polymerization method, a suspension polymerization method, an emulsion polymerization method and the like can be used.

In the toner for developing an electrostatic image of the present invention, a charge control agent can be obtained as needed in order to further stabilize the chargeability.

[0074] Charge control agents known in the art today include:

To control the toner to be negatively charged,
For example, an organic metal complex and a chelate compound are effective, and examples thereof include a monoazo metal complex, an acetylacetone metal complex, an aromatic hydroxycarboxylic acid, and an aromatic dicarboxylic acid-based metal complex. Other examples include aromatic hydroxycarboxylic acids, aromatic mono- and polycarboxylic acids and their metal salts, anhydrides, esters, and phenol derivatives such as bisphenol.

To control the toner to be positively charged,
For example, denatured products such as nigrosine and fatty acid metal salts; tributylbenzylammonium-1-hydroxy-4-
Quaternary ammonium salts such as naphthosulfonate and tetrabutylammonium tetrafluoroborate, and onium salts such as phosphonium salts, which are analogs thereof, and lake pigments thereof; triphenylmethane dyes and lake pigments thereof. (As the lake-forming agent, phosphotungstic acid, phosphomolybdic acid, phosphotungsten molybdic acid, tannic acid, lauric acid, gallic acid, ferricyanide, ferrocyanide, etc.); metal salts of higher fatty acids; acetylacetone metal complex; dibutyltin Diorganotin oxides such as oxide, dioctyltin oxide and dicyclohexyltin oxide; and diorganotin borates such as dibutyltin borate, dioctyltin borate and dicyclohexyltin borate. These can be used alone or in combination of two or more. Among these, charge control agents such as nigrosine compounds and organic quaternary ammonium salts are particularly preferably used.

In the toner of the present invention, charging stability,
In order to improve developability, fluidity and durability, it is preferable to add silica fine powder.

The silica fine powder used in the present invention is BE
The specific surface area by nitrogen adsorption measured by the T method is 30 m ² / g
Those within the above range (particularly 50 to 400 m ² / g) give good results. It is preferable to use 0.01 to 8 parts by weight, preferably 0.1 to 5 parts by weight of silica fine powder with respect to 100 parts by weight of the toner.

The silica fine powder used in the present invention may be, if necessary, silicone varnish, various modified silicone varnishes, silicone oil, various modified silicone oils, silane coupling agent, It is also preferable to use a treating agent such as a silane coupling agent having a group or another organosilicon compound, or a combination of various treating agents.

Other additives include lubricants such as Teflon, zinc stearate, and polyvinylidene fluoride (in particular, polyvinylidene fluoride); polishing agents such as cerium oxide, silicon carbide, and strontium titanate (in particular, titanic acid). Fluidity-imparting agents such as titanium oxide, aluminum oxide, hydrophobic titanium oxide, and hydrophobic aluminum oxide (particularly preferably hydrophobic); anti-caking agents; carbon black, zinc oxide, antimony oxide; A conductivity imparting agent such as tin oxide; a small amount of white fine particles or black fine particles having a polarity opposite to that of the toner particles may be used as a developing property improver.

For the purpose of improving the releasability at the time of fixing with a hot roll, a wax-like substance such as low molecular weight polyethylene, low molecular weight polypropylene, microcrystalline wax, carnauba wax, sasol wax and paraffin wax is added to 100 parts by weight of the binder resin. Adding 0.5 to 10 parts by weight to the toner is also a preferred embodiment of the present invention.

Further, when the toner of the present invention is used as a two-component developer, it is used by mixing with a carrier powder.
In this case, the mixing ratio of the toner and the carrier powder is 0.1 to 50% by weight as a toner concentration, preferably 0.5 to 1%.
0% by weight, more preferably 3 to 5% by weight.

As the carrier that can be used in the present invention, known carriers can be used. For example, powders having magnetism such as iron powder, ferrite powder, and nickel powder, and powders obtained by treating the surfaces thereof with a fluorine resin, a vinyl resin, a silicone resin, or the like can be given.

Further, the toner of the present invention can be used as a magnetic toner by further containing a magnetic material. In this case, the magnetic material also serves as a colorant. Examples of the magnetic material contained in the magnetic toner of the present invention include iron oxides such as magnetite, hematite, and ferrite; metals such as iron, cobalt, and nickel; or aluminum, cobalt, copper, lead, magnesium, and tin of these metals. Zinc, antimony,
Examples include alloys of metals such as beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten, and vanadium, and mixtures thereof.

These magnetic materials have an average particle size of 0.1 to 2 μm.
m, preferably 0.1 to 0.5 μm.
The amount contained in the toner is preferably about 20 to 200 parts by weight, particularly preferably 40 to 150 parts by weight, per 100 parts by weight of the resin component.

The magnetic material has a coercive force of 20 to 150 Oe and a saturation magnetization of 50 to 200 emu / g and a remanence of 2 to 20 emu / g when applied with 10 K Oe.
g are preferred.

The colorant that can be used in the toner of the present invention includes any appropriate pigment or dye. As the coloring agent, for example, carbon black, aniline black, acetylene black, naphthol yellow,
Hansa Yellow, Rhodamine Lake, Alizarin Lake, Bengala, Phthalocyanine Blue, Indanthrene Blue and the like. These are used in an amount necessary and sufficient to maintain the optical density of the fixed image, and are preferably added in an amount of 0.1 to 20 parts by weight, preferably 1 to 10 parts by weight based on 100 parts by weight of the resin component. For the same purpose, a dye is further used. For example, there are azo dyes, anthraquinone dyes, xanthene dyes, methine dyes and the like, and 0.1 to 20 parts by weight, preferably 0.3 to 10 parts by weight, per 100 parts by weight of the resin component.
Good addition amount by weight.

To prepare the toner for developing an electrostatic image according to the present invention, a binder resin, a pigment or dye as a colorant,
The magnetic material, if necessary, the charge control agent, other additives, etc. are sufficiently mixed by a mixer such as a Henschel mixer or a ball mill, and then melted and kneaded using a heat kneader such as a heating roll, a kneader, or an extruder. A metal compound, a pigment, a dye, and a magnetic substance are dispersed or dissolved in a resin in which the resins are combined with each other by summing and kneading, and after cooling and solidifying, performing pulverization and classification to obtain a toner according to the present invention. Can be done.

Further, if necessary, desired additives are sufficiently mixed with a mixer such as a Henschel mixer to obtain the electrostatic image developing toner according to the present invention.

The image forming method of the present invention will be specifically described with reference to FIG.

Reference numeral 1 denotes a rotating drum type electrostatic image carrier (hereinafter referred to as a photoconductor). The photoconductor 1 includes a conductive base layer 1b made of aluminum or the like and a photoconductive layer 1 formed on the outer surface thereof.
a is a basic constituent layer, and is rotated at a predetermined peripheral speed (process speed) clockwise in the drawing.

In this embodiment, an organic photoconductor (OPC) is used as the photosensitive member. The photosensitive drum 1 has an outer diameter of 30 mm
φ.

Reference numeral 2 denotes a charging roller, which basically has a core metal 2b at the center and a conductive elastic layer formed on the outer periphery thereof. The charging roller 3 is pressed against the surface of the photoconductor 1 with a pressing force, and is rotated by the rotation of the photoconductor 1. Reference numeral 3 denotes a charging bias power supply for applying a voltage to the charging roller 2, and the surface of the photoconductor 1 is charged to a predetermined polarity / potential by applying a bias to the charging roller 3. Next, an electrostatic latent image is formed by the image exposure 4, and is sequentially visualized as a toner image by the developing unit 5.

In this embodiment, the outer diameter of the charging roller 2 is 16 m.
mφ, styrene-butadiene rubber (SBR) is used for the conductive rubber layer 2a, and nylon resin is mainly used for the surface layer. The hardness of the charging roller 2 is 64 ° (ASKER-
C). Reference numeral 3 denotes a power supply unit that applies a voltage to the charging roller 2 and supplies a predetermined voltage to the metal core 2b of the charging roller 2. In FIG. 1, 3 indicates a DC voltage. A voltage obtained by superimposing an AC voltage on a DC voltage may be used.

The contact pressure of the charging member to the photosensitive member is 5 to 50.
The absolute value of the DC voltage applied to the charging member is preferably set to 200 to 1.5 kV at 0 g / cm. The contact pressure is more preferably from 10 to 100 g / cm.

The AC voltage is preferably not applied in order to prevent the toner from adhering to the photosensitive member. However, when the AC voltage is applied, it is preferable to adjust the peak-to-peak voltage to 500 to 5000 V and the frequency to 50 to 3000 Hz, respectively. .

The toner or toner external additive that has passed through the cleaning blade 9 easily adheres to and accumulates on the charging member, resulting in uneven charging and fogging. Therefore, it is better to have a cleaning mechanism for cleaning the charging roller. In the drawing, the cleaning member 2C contacts the charging member only during operation, and the amount of penetration is 0.5 mm or more.

In the cleaning step according to the present invention, the photosensitive drum after the transfer of the toner image is generally cleaned by wiping off the residual toner after transfer and other contaminants by a cleaning member such as a blade or a roller of a cleaner. The surface is formed and repeatedly used for image formation.

The cleaning step can be performed simultaneously in the charging step, the developing step, or the transfer step related to the electrophotographic method.

The linear pressure is calculated by the following equation.

(Linear pressure) [g / cm] = (total pressure applied to the transfer member) [g] / (contact length) [cm]

Reference numeral 6 denotes a transfer roller, which is basically composed of a central metal core 6b and a conductive elastic layer 6a forming the outer periphery thereof. The transfer roller 6 is pressed against the surface of the photoreceptor 1 with a pressing force, and is rotated at a constant speed or a difference in the peripheral speed of the photoreceptor 1. The transfer material 8 is transferred between the photoreceptor 1 and the transfer roller 6, and at the same time, a bias having a polarity opposite to that of the toner is applied to the transfer roller 6 from a transfer bias power supply 7 to transfer the toner image on the photoreceptor 1. Lumber 8
Is transferred to the surface side of

In this embodiment, the outer diameter of the transfer roller 6 is 16 mmφ, and the conductive elastic layer 6a is made of a foamed ethylene-propylene-diene terpolymer (EPDM).
Was used. The hardness of the transfer roller 6 is 30 ° (ASKER-
C). The contact pressure of the transfer roller 6 against the photoconductor 1 is set to 0.
5 g / cm or more, preferably 3 g / cm or more
00 g / cm or less is more preferable.

The DC voltage applied to the transfer roller is preferably set to an absolute value of 3.5 kV to 7.0 kV.

Toners or toner external additives scattered from the developing device onto the drum or those slipping off from the cleaning blade 9 adhere to, deposit on, transfer from the developing device,
Poor transfer and uneven transfer occur.

Therefore, in order to clean the transfer roller, it is preferable to apply a voltage in the opposite direction to the voltage applied during transfer between the transfer materials. At this time, the DC voltage is preferably 3.5 kV to 7.0 kV in absolute value.

It is better to have a cleaning mechanism for cleaning the transfer roller.

Next, the transfer material 8 is conveyed to a fixing device 11 having a heating roller 11a having a built-in halogen heater and an elastic pressure roller 11b pressed against the heating roller 11a with a pressing force. By passing through the gap, the toner image is fixed on the transfer material 8 and is discharged as an image formed product.

In the image forming method of the present invention, it is necessary to reduce the heat capacity of the heating roller 11a in order to shorten the wait-up time.
The core metal thickness of 1a needs to be 1 mm or less. As the material of the metal core, any metal or alloy can be used as long as strength and stability can be maintained, but carbon steel is preferable.

The heating roller 11a is preferably coated with a resin having good release properties. These resins include, for example, fluororesins, silicone resins, amide resins and the like.

It is preferable to have a mechanism for cleaning the fixing roller. Examples of such a mechanism include a cleaning web, a cleaning pad, and the like, and it is preferable to have the cleaning web 11c as a cleaning mechanism.

In this image forming method, the speed (process speed) at which the transfer material passes between 11a and 11b is 150 mm.
/ Sec (A4 vertical feed 22.5 sheets / min) or more.

The heating roller 11a of the fixing device 11 shown in FIG.
In the figure, the heater 12 is included inside the metal core 14, and the resin layer 13 is provided on the surface of the metal core 14,
In the pressure roller 11b, the elastic layer 15 is provided on the surface of the core 16.

On the surface of the photoreceptor 1 after the transfer of the toner image, the contaminant contaminants such as untransferred toner are cleaned by a cleaning device provided with an elastic cleaning blade pressed against the photoreceptor 1 in the counter direction. The static electricity is removed by the device 10 and an image is repeatedly formed.

The basic configuration and features of the present invention have been described above, and the present invention will be specifically described below with reference to examples. However, this does not limit the invention in any way. Parts in the following formulations are parts by weight.

Synthesis Example 1 A four-necked flask equipped with a nitrogen gas inlet tube, a condenser, a stirrer, and a thermometer was charged with 200 parts of ion-exchanged water, 80 parts of styrene, 20 parts of n-butyl acrylate, and four parts of a polyfunctional polymerization initiator. 0.40 parts of functional 1,4-bis (t-butylbaroxycarbonyl) cyclohexane (HTP) was charged, and suspension polymerization was performed at a polymerization temperature of 90 ° C. for 25 hours.
Thereafter, the mixture was cooled, washed with water, and dried to obtain a high molecular weight styrene-based copolymer. This styrene copolymer is referred to as a binder resin A. When the molecular weight distribution of the binder resin A was measured by GPC, it had a peak (P2) at a molecular weight of 51,000.

Next, 800 parts of xylene was charged into the above-mentioned polymerization apparatus, and the mixture was stirred and heated at 140 ° C. under a stream of nitrogen gas to keep 84 parts of styrene, 16 parts of n-butyl acrylate, and diene as polymerization initiator B. -T-butyl peroxide (DT
BP, 0.9 part of a half life of 140 ° C. at a temperature of 140 ° C.), and P-menthane hydroperoxide as a polymerization initiator A (P-menthane hydroperoxide)
e, half-life at a temperature of 140 ° C. 5.0 hours) A mixture of 0.2 part was dropped over 2 hours using a continuous dropping apparatus, and polymerization was carried out for 4 hours to obtain a binder resin B which is a low molecular weight polymer. A polymerization solution was obtained. When the molecular weight distribution of the binder resin B was measured by GPC, it had a peak (P1) at a molecular weight of 10,000.

The above polymerization solution (binder resin B: 70 parts contained)
Inside, 30 parts of binder resin A and 4 parts of low molecular weight polypropylene (weight average molecular weight = about 10,000) were added at 100 ° C.
For about 4 hours with sufficient stirring to dissolve and mix, and then remove the solvent by distillation under reduced pressure (about 20 mmHg, about 40 ° C.).
For 24 hours) and then under reduced pressure of about 20 mmHg 8
The mixture was heated to 0 ° C. and decompressed for 1 hour.
I got

Comparative Synthetic Example 1 800 parts of xylene was charged into the same polymerization apparatus as described in Synthetic Example 1, stirred and heated under a nitrogen gas stream, kept at 140 ° C., 84 parts of styrene, n-butyl acrylate 16 Part, di-t-butyl peroxide (DTB) as a polymerization initiator
P) 1.0 part of the mixture was added dropwise over 2 hours using a continuous dropping device, and polymerization was carried out over 4 hours to obtain a polymerization solution of binder resin C, which is a low molecular weight polymer. The binder resin C
Was measured by GPC and found to have a peak (P1) at a molecular weight of 10,000.

The above polymerization solution (binder resin C: 70 parts contained)
In the same manner as in Synthesis Example 1, 30 parts of binder resin A and 4 parts of low molecular weight polypropylene were mixed, and binder resin I for toner I was mixed.
I was obtained.

This resin II was further subjected to a reduced pressure treatment at 80 ° C. for 2 hours to obtain a binder resin for toner III.

Comparative Synthesis Example 2 As in Comparative Synthesis Example 1, di-t-
Binder resin E was obtained using 1.5 parts of butyl peroxide (DTBP). The binder resin E peaked at 90,000 (P
1). Binder resin E7 as in Synthesis Example 1
30 parts of the binder resin A and 4 parts of low molecular weight polypropylene were mixed in the 0 part-containing solution, and the solvent was removed to obtain a binder resin IV for toner.

Comparative Synthesis Example 3 Synthesis Example 1 The polymerization initiator in binder resin A was changed to 0.2 part of 2,2'-azobis (2,4-dimethylvaleronitrile) and suspended at a polymerization temperature of 80 ° C. for 9 hours. Polymerization was performed to obtain a binder resin F in the same manner as in Synthesis Example 1. The molecular weight distribution of this binder resin F was measured by GPC and found to have a peak (P2) at a molecular weight of 250,000.

Next, a binder resin B was synthesized in the same manner as in Synthesis Example 1, and this solution (binder resin B, containing 70 parts) was used.
30 parts of low-molecular-weight polypropylene and 4 parts of low-molecular-weight polypropylene were similarly mixed and treated under reduced pressure to obtain a resin V for toner.

Synthesis Example 2 The polymerization initiator in Synthesis Example 1 (binder resin A) was changed to 0.4 part of tris (t-butylperoxy) triazine,
The suspension polymerization was carried out at a polymerization temperature of 80 ° C. for 8 hours to produce Synthesis Example 1.
In the same manner as in the above, a binder resin G was obtained.

When the molecular weight distribution of the binder resin G was measured by GPC, it had a peak (P2) at a molecular weight of 600,000.

Synthesis Example 1 In the same manner as in Binder Resin B, 85 parts of styrene, 15 parts of n-butyl acrylate, and di-t-butyl peroxide as polymerization initiator B (DTBP: half-life at 140 ° C. 6 hours) 4.0 parts, polymerization initiator A
A mixture of 1.0 part of 2,5-dimethylhexane 2,5-dihydroperoxide (half-life of 30 hours at a temperature of 140 ° C.) was added dropwise to a solution of 800 parts of xylene over 2 hours, and polymerization was performed for 8 hours. Binder resin H was obtained.

The binder resin H had a peak (P1) at a molecular weight of 0.4000.

Further, in the same manner as in Synthesis Example 1, the binder resin H
30 parts of binder resin G and 4 parts of low molecular weight polypropylene were mixed in a solution containing 70 parts, and the solvent was removed to obtain a binder resin VI for toner.

Synthesis Example 3 200 parts of ion-exchanged water, 80 parts of styrene, 20 parts of n-butyl acrylate, and a polymerization initiator 2, were placed in a four-necked flask equipped with a nitrogen gas inlet tube, a condenser, a stirrer, and a thermometer.
0.13 parts of 2-bis (4,4-tert-butylperoxycyclohexyl) propane was charged, and the polymerization temperature was set to 90.
The suspension polymerization was carried out at 25 ° C for 25 hours. Thereafter, the mixture was cooled, washed with water, and dried to obtain a high molecular weight polymer. This polymer is referred to as a binder resin J. When the molecular weight distribution of the binder resin J was measured by GPC, it had a peak (P2) at a molecular weight of 800,000.

Next, a binder resin B was synthesized in the same manner as in Synthesis Example 1, and 30 parts of the binder resin J and 4 parts of low-molecular-weight polypropylene were similarly mixed with this solution (containing 70 parts of the binder resin B). This was processed to obtain a resin VII for toner.

Comparative Synthesis Example 4 76 parts by weight of styrene 23 parts by weight of n-butyl acrylate 0.30 part by weight of divinylbenzene 0.8 part by weight of di-tert-butyl peroxide

The above materials were added dropwise to 200 parts by weight of xylene heated to the reflux temperature over 4 hours. The polymerization was completed under xylene reflux (138-144 ° C.) for another 4 hours,
Xylene was removed while heating to 200 ° C. under reduced pressure. The resin obtained in this manner is referred to as a resin VIII.

Comparative Synthesis Example 5 73 parts by weight of styrene 24 parts by weight of n-butyl acrylate 0.8 parts by weight of di-tert-butyl peroxide

The above material was dropped into 200 parts by weight of xylene heated to 80 to 90 ° C. over 2 hours. Further, the polymerization was completed under reflux of xylene for 6 hours, and xylene was removed while heating to 200 ° C. under reduced pressure.

The resin thus obtained is referred to as a resin IX.

Example 1 100 parts of binder resin VII 90 parts of iron tetroxide (average particle size 0.2 μm) 2 parts of nigrosine

The above materials were thoroughly mixed in a blender.

Thereafter, the mixture was kneaded with a twin-screw kneading extruder set at 80 ° C. The obtained kneaded material is cooled, coarsely pulverized by a cutter mill, and then finely pulverized using a fine pulverizer using a jet stream, and the obtained finely pulverized powder is subjected to a multi-divided classifier utilizing the Coanda effect. And weight-average particle size 8.5.
A black fine powder (magnetic toner) of μm was obtained.

The obtained black fine powder (magnetic toner) 100
In the part, positively charged hydrophobic fumed silica (BET specific surface area: 1
30 m ^{2 /} g), and mixed with a Henschel mixer to obtain a positively charged magnetic toner having silica on the surface of toner particles.

The obtained magnetic toner (0.2 g) was dissolved in THF (tetrahydrofuran) (20 ml) to remove the magnetic substance and other insoluble components by a filter.
Was measured. Table 1 shows the measurement results. The content of the resin component having a molecular weight of 50,000 or less was about 69% by weight. Also,
The styrene resin component that did not dissolve in THF was not substantially present.

Each condition in the image forming apparatus shown in FIG. 1 is shown below.

Contact pressure of charging roller to photoconductor: 50 g / cm Applied voltage: -1400 V (DC) Contact pressure of transfer roller to photoconductor: 20 g / cm (linear pressure) Applied voltage: -6000 V (DC Peripheral speed difference with respect to photoconductor: 0 Contact pressure of cleaning blade: 20 g / cm Developing bias condition Vpp: 1300 V (AC) Vf: 1800 Hz Vdc: −210 V (DC) Distance between photoconductor and developer carrier: 300 μm Heat fixing roller: A polytetrafluoroethylene resin (PTFE) layer is provided on a core metal made of carbon steel having a thickness of 0.9 mm. Inside, there are two halogen lamps,
The outer circumference of the fixing roller has a predetermined temperature (about 160 to 200
° C).

Pressure roller: A 2 mm silicone rubber layer is provided as an elastic layer on a core metal made of carbon steel having a thickness of 1 mm.

Process speed: 200 mm / sec Using the magnetic toner described above and using A4 size plain paper as a transfer material, a 20,000 sheet image endurance test was performed. 2
Even after 10,000 copies, high-quality images with excellent image quality were obtained.

Image density, fog, presence or absence of filming,
Transfer roller stains, amount of silica accumulated on the developer stay,
Table 2 shows the amount of the residual monomer in the toner and the result of the odor test at the time of fixing. Monitor 3 for odor test during fixing
It is a relative evaluation by a person.

Next, an unfixed image was obtained by using the above-mentioned toner in a modified machine in which the fixing device of the image forming apparatus was removed. On the other hand, the detached fixing device was modified into a heat roller external fixing device having a variable temperature, and a fixing test and an offset test of an unfixed image were performed using the fixing device.

The nip of the external fixing device was set to 4.0 mm, the process speed was set to 200 mm / s, and
The temperature is controlled every 5 ° C. in a temperature range of 0 ° C., and an unfixed image is fixed at each temperature.
was rubbed with lens-cleaning paper applying a load of m ^2, and the fixing temperature decrease in image density ratio before and after the rubbing is 2% or less and the fixing initiation temperature. As a result, the fixing start temperature was as low as 170 ° C.
It was excellent in low-temperature fixability. Further, the offset start temperature was as high as 250 ° C. or more, and the offset resistance was excellent.

Next, using the image forming apparatus according to the present invention,
After continuously copying 100 sheets of A3 size image, it was allowed to stand for 30 seconds, and then 5 sheets of A3 solid white image were copied. The outflow of the offset toner was evaluated based on the degree of contamination on both sides of the copy paper at this time. As a result, there was no stain on both surfaces, and the toner was excellent in preventing the offset toner from flowing out.

The magnetic toner was allowed to stand in a dryer at 50 ° C. for 2 weeks, and the blocking resistance of the toner was tested. No problem was found.

Table 3 shows the results.

Example 2 Evaluation was made in the same manner as in Example 1 except that the binder resin I was used as the binder resin.

The results are shown in Tables 1, 2 and 3.

Example 3 Evaluation was made in the same manner as in Example 1 except that the binder resin VI was used as the binder resin. The results are shown in Tables 1, 2 and 3.

Example 4 The image of the magnetic toner used in Example 1 was evaluated using NP2020 (a copying machine manufactured by Canon Inc.).

From the beginning, an excellent image having a high image density of 1.40 and no fog was obtained. Even after copying 200,000 sheets, a good image without fogging and no filming was obtained at an image density of 1.37. There was also little odor.

Comparative Example 1 Evaluation was made in the same manner as in Example 1 except that resin II was used as the binder resin.

Comparative Example 2 Evaluation was made in the same manner as in Example 1 except that resin III was used as the binder resin.

Comparative Example 3 Evaluation was made in the same manner as in Example 1 except that resin IV was used as the binder resin.

Comparative Example 4 Evaluation was made in the same manner as in Example 1 except that resin V was used as the binder resin.

Comparative Example 5 Evaluation was made in the same manner as in Example 1 except that resin VIII was used as the binder resin.

Comparative Example 6 Evaluation was made in the same manner as in Example 1 except that resin IX was used as the binder resin.

[0163]

[Table 1]

[0164]

[Table 2]

[0165]

[Table 3]

[0166]

As described above, the toner of the present invention containing the above components exhibits excellent low-temperature fixability and offset prevention. Further, by using an image forming method using a heat roller having a core metal thickness of 1 mm or less as a fixing method, it is possible to shorten a wait-up time and speed up an electrophotographic process.

Further, the toner of the present invention has a small amount of volatile components such as residual monomers, and has a small odor during copying.

Further, by using the above-described image forming method of developing with the toner of the present invention, an image forming apparatus with less ozone odor and toner odor is provided. Further, it is possible to provide an image of high image density and excellent image quality without fog for a long time without fixing the toner on the charging member or the surface of the photosensitive member.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an image forming apparatus for performing an image forming method of the present invention.

FIG. 2 shows a GPC chromatogram of a resin component of the toner used in Example 1 of the present invention.

[Explanation of Signs] 1 electrostatic image carrier (photoreceptor) 2 charging roller 3 charging bias application power supply 4 image exposure 5 developing means 6 transfer roller 7 transfer bias application power supply 8 transfer material 9 cleaning means 10 charge removal exposure 11 fixing means

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masami Fujimoto 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Minoru Shijojo 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Incorporated (72) Inventor Toshiaki Nakahara 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) References JP-A 1-219764 (JP, A) JP-A 3-85547 (JP) JP-A-61-123853 (JP, A) JP-A-64-70765 (JP, A) JP-A-58-37651 (JP, A) JP-A-59-46664 (JP, A) 3-121462 (JP, A) JP-A-4-37775 (JP, A) JP-A-4-190245 (JP, A)

Claims (4)

(57) [Claims] An electrostatic latent image carrier is charged by applying a voltage.
Contacting the members to charge the electrostatic latent image carrier,
An electrostatic latent image is formed by light, and the electrostatic latent image is formed by toner.
Developing, the toner formed on the electrostatic latent image carrier
While pressing the transfer material with the transfer member to which the voltage is applied
Step of transferring to a transfer material, heating and pressing the transferred toner image
Static charge used in an image forming method having a fixing step
A toner for image development, the toner is contained polymerized styrene resin in the presence of a trifunctional or higher polyfunctional polymerization initiator, in the molecular weight distribution of GPC, the molecular weight 3.5 × 10 ³ to 5 A region having a maximum value (P ₁ ) in a region of × 10 ⁴ , a maximum value (P ₂ ) or a shoulder in a region having a molecular weight of 1 × 10 ⁵ or more, and a molecular weight of 3
It contains 15% or less of a resin component in an area of 10 ³ or less , and
Contains 5-50% of resin component in the region of 1 × 10 ⁵ or more
A toner for developing an electrostatic image, wherein the content of styrene and benzaldehyde contained in the toner is 100 ppm or less. 2. A polymerization initiator A having a long half-life at least.
Under the condition that the ratio τ _A / τ _B of the half life τ _A and the half life τ _B at the polymerization temperature is 1.5 or more in the presence of two kinds of polymerization initiators having different polymerization initiators B having a short half life. The electrostatic image developing toner according to claim 1, further comprising a resin component polymerized in (1). 3. An electrostatic latent image carrier is charged by applying a voltage to the electrostatic latent image carrier to charge the electrostatic latent image carrier, and the charged electrostatic latent image carrier is exposed to light to expose the electrostatic latent image carrier. forming an image, an electrostatic latent image formed, containing polymerized styrene resin in the presence of a trifunctional or higher polyfunctional polymerization initiator, in the molecular weight distribution of GPC, the molecular weight 3.5 × 10 ³ A resin component having a maximum value (P ₁ ) in a region of ５5 × 10 ⁴ , a maximum value (P ₂ ) or a shoulder in a region having a molecular weight of 1 × 10 ⁵ or more, and a region having a molecular weight of 3 × 10 ³ or less 15% or less, having a molecular weight of 1 × 1
0 resin component of ⁵ or more regions are contained 5-50%, and developed with styrene and an electrostatic image developing toner content is 100ppm or less of benzaldehyde contained in the toner to form a toner image, formed The transferred toner image is transferred onto the transfer material while pressing the transfer material with a transfer member to which a voltage is applied, and the toner image on the transfer material is heated and pressed with a heat roller having a core metal thickness of 1 mm or less. Image forming method. 4. A polymerization initiator A having at least a long half-life
Under the condition that the ratio τ _A / τ _B of the half life τ _A and the half life τ _B at the polymerization temperature is 1.5 or more in the presence of two kinds of polymerization initiators having different polymerization initiators B having a short half life. 4. The image forming method according to claim 3, wherein the toner contains the resin component polymerized in the step.