JPH07101320B2 - Method of developing electrostatic latent image - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for developing an electrostatic latent image, and more particularly to a method for developing a latent image on an image carrier in electrophotography.

(Prior Art) Conventionally, as a method of developing a latent image on an image carrier such as a photoconductor drum in an electrophotographic copying apparatus, a one-component developer that imparts magnetism to the toner itself and does not require a carrier is used. In some cases, a two-component developer composed of a non-magnetic toner or a toner in which the magnetism is slightly insoluble and a magnetic carrier is used, but the former one-component developer has a drawback that it is inferior in temperature and humidity resistance. On the other hand, the latter two-component developer is widely used because it is easy to control the triboelectric charge of the toner, has excellent developability, and can impart an arbitrary color to the toner. In such a developer,
In order to improve the resolution and gradation reproducibility of the obtained image surface and other general image quality, attempts have been made to reduce the particle size of the carrier and toner.

For example, Japanese Patent Application Nos. 58-57746, 59-222847, and 59-
222851-3, 59-223467, etc. have a conventional 80-500μ
There is described a technique of developing in a non-contact manner by using a small particle size carrier having a particle size of 50 μm or less instead of a large particle size m of m and using a developer having a particle size of mixed toner of 20 μm or less.

However, when the carrier in the developer has a small particle size, the triboelectric chargeability between the toner and the carrier is deteriorated, and therefore the electrostatic and physical binding force between the carrier and the developer carrying carrier (for example, developing sleeve) and the toner. Becomes weaker, the carrier and toner scatter during the image formation to contaminate the inside of the apparatus, toner adheres to the image surface to cause fogging, and carrier adheres (hereinafter referred to as carrier adhesion). do it,
There are some problems such as not being able to obtain high quality images.

Further, when the carrier has a small particle diameter, it is difficult to form a thin layer of the developer on the developer carrying carrier, and a non-uniform developer layer is formed, which may cause unevenness or image omission in the image. hand,
It becomes difficult to obtain high-quality images.

Furthermore, when copying a large number of sheets, a strong pressure is applied in the process of forming a thin layer of the developer on the developer carrier, so that the so-called filming phenomenon in which the toner physically adheres strongly to the carrier increases. However, the toner and the carrier cannot be effectively triboelectrically charged to cause fog or toner scattering, the carrier with the toner filmed is developed and carrier adheres, or a good thin layer cannot be formed. However, it is difficult to obtain a clear image.

On the other hand, recently, (a) suppressing overheat deterioration of the copying machine, (b) preventing heat deterioration of the photoconductor,
(C) Shorten the warm-up time required to raise the temperature of the heat roller to a temperature at which it can be fixed after the fixing device is activated, and (d) lower the temperature of the heat roller by absorbing heat to the transfer paper. To reduce the power consumption of the fixing heater and reduce the temperature of the heat roller to meet the requirements such as making the size smaller to enable continuous copying over a number of times and (e) increasing the thermal safety. There is a strong demand for enabling the fixing process in a lowered state. Therefore, it is necessary for the toner to be well fixed at a low temperature.

Moreover, in the toner, it can exist stably as a powder without agglomeration under the use or storage environment conditions,
That is, it is necessary to have excellent blocking resistance,
Further, in the heat roller fixing method which is preferable as the fixing method, an offset phenomenon, that is, a part of the toner forming the image at the time of transfer is transferred to the surface of the heat roller, and this is retransferred to the transfer paper which is sent next to form an image. Since the phenomenon of fouling is likely to occur, it is necessary to provide the toner with the performance of preventing the occurrence of the offset phenomenon, that is, the offset resistance.

However, when a low-temperature fixing property is given to the toner, filming on the carrier results in defects in durability and image quality under high temperature and high humidity conditions.

Various investigations have been made in the past to solve the above-mentioned drawbacks, for example, JP-A-57-178250 and 61-110155.
No. 61-110156, by a resin obtained by reacting a polymer having a carboxyl group with a metal compound,
Attempts have been made to expand offset resistance, blocking resistance, and fixing temperature range, but the one-component developer disclosed in the above publication or the two-component developer using an iron powder carrier is triboelectrically charged under high temperature and high humidity conditions. Property is unstable, filming easily occurs on the carrier particles and the surface of the photoconductor, and cleaning failure occurs due to fusion to the cleaning blade, resulting in poor continuous images and poor durability. It is a thing.

(Object of the invention) The object of the present invention does not cause problems such as contamination of the inside of the device due to carrier and toner scattering, carrier adhesion and fogging due to the scattering carrier and toner adhering to the image surface, Further, an appropriate triboelectric charge is imparted between the carrier and the toner to achieve good development, and as a result, a development method capable of forming a clear image excellent in resolution and gradation reproducibility is provided. is there.

Another object of the present invention is to provide a developing method capable of forming a uniform and favorable thin layer and thereby obtaining a high-quality image without image unevenness or image dropout.

Another object of the present invention is to form a good thin layer even when copying a large number of sheets, without causing problems such as carrier adhesion and fogging, and providing proper frictional electrification between the carrier and toner. Development is achieved, and as a result, a development method capable of forming an image with excellent image quality is provided.

Still another object of the present invention is to provide a developing method capable of obtaining a clear image without causing problems such as image loss even under high temperature and high humidity environmental conditions.

Still another object of the present invention is to provide a developing method capable of fixing at a low temperature, and having excellent offset resistance and blocking resistance and at the same time excellent durability, temperature and humidity resistance, and obtaining a good image. To do.

(Structure and Operation and Effect of the Invention) The above-mentioned object of the present invention is to generate an oscillating electric field in the developing area, and to develop the latent image formed on the image carrier with the carrier on the developer carrier and the toner-containing developer layer. In this case, the developer layer is a thin layer of 10 to 1000 μm, and the main component resin of the toner has a molecular weight distribution of at least two groups of a low molecular weight polymer component and a high molecular weight polymer component, and the molecular weight distribution is a gel. In the molecular weight distribution curve by permeation chromatography, the maximum value of the low molecular weight polymer component is 1 × 10 ³ to 2 × 10 ⁴ , and the maximum value of the high molecular weight polymer component is 1 × 10 ⁵ to 2. × a 10 ^6, and the main component resin, the following (a), the developing method of the electrostatic latent image, which is a polyvalent metal salt of a polymer derived from (b) and (c) To be achieved.

(A) Styrene-based monomer (b) Acrylic acid ester-based monomer or methacrylic acid ester-based monomer (c) Monomer represented by the following general formula (A): General formula (A) (In the formula, R ₁ represents a hydrogen atom or a methyl group, L represents a divalent linking group having an ester bond and having 3 or more carbon atoms, and may have a substituent.) Furthermore, the polyvalent metal compound described above. Preferably, it is a zinc group metal compound or an alkaline earth metal compound.

According to the developing method using the developer having such a constitution, the resin which is the main component of the toner exhibits a cross-linked structure by the ionic bond between the carboxy group and the metal atom in the polymer component, but the cross-linking by the covalent bond. It is connected much more loosely than the structure. Therefore, even if the content of the low molecular weight polymer component in the resin is increased, the offset resistance and blocking resistance are not deteriorated by the cross-linking by the ionic bond, and since it is due to the gradual ionic bond, it is different from the cross-linking by the covalent bond. Then, the properties of the low molecular weight polymer component are reflected, and the fixability is also improved. Further, by containing an ionic crosslinked structure and a high molecular weight polymer component, it becomes hard, tough and has high insulation.

For this reason, the carrier is effectively triboelectrically charged, and the carrier has a strong electrostatic force with the toner and the developer carrier, and as a result, carrier scattering and toner scattering can be prevented, and there is no clear fog or carrier adhesion. An image is obtained. Further, the toner containing the above-mentioned specific resin as a binder has a high fluidity and has an effect of improving the fluidity of the developer mixed with the carrier. Therefore, the toner is uniformly distributed on the developer transport carrier. It is possible to form a different developer layer and prevent image unevenness and image dropout.

Furthermore, the toner using the resin as a binder has a three-dimensional structure due to metal cross-linking and has high hydrophobicity. Therefore, even if an oscillating electric field is applied under high temperature and high humidity, charge leakage does not occur, A clear image with no missing images can be obtained.

Further, since a thin layer of the developer can be formed on the developer carrier by the toner having good fluidity, the bond strength between the carrier of the developer and the toner and the bond strength between the carrier and the carrier of the developer carrier are weak. However, since the developer layer can be made extremely thin, it is sufficiently fixed to the developer transport carrier (hereinafter referred to as a sleeve).

Further, the carrier particles in the present invention are preferably coated with a resin, and preferably have a spherical and smooth surface condition. Such a carrier is effectively triboelectrically charged with the toner, the electrostatic coupling force between the toner and the sleeve is strengthened, and as a result, carrier scattering and toner scattering can be prevented, and fogging and carrier adhesion are prevented, A clear image can be obtained. In addition, by using a resin-coated carrier, the flowability of the developer is good even with a small particle size carrier, and a uniform thin layer of the developer can be formed on the developer transport carrier, resulting in image unevenness and image bleeding. Can be prevented. Furthermore, even when copying a large number of sheets, the resin-coated carrier has a good releasability, and even if a strong pressure is applied, it does not physically adhere strongly to the toner, and filming of the toner on the carrier occurs. Without, as a result, the fogging,
A clear and clear image can be obtained with good durability without toner scattering and carrier adhesion.

In particular, as a resin used for resin coating of a carrier, a copolymer obtained by polymerization of a styrene monomer as a hard component and acrylic acid (or methacrylic acid) or its ester exhibiting a tough and flexible function is used. Then, while exhibiting the characteristics of both of these monomer components, the drawbacks thereof can be eliminated at the same time. That is, the brittleness due to the styrene type is eliminated by acrylic (or methacrylic) acid or its ester, and while the flexibility due to the latter is maintained, an appropriate hardness can be imparted by the styrene type component. Such physical properties bring about an improvement in releasability, prevention of adhesion to the toner, and the like, as described above.

Furthermore, in the present invention, since the resin-coated carrier is convenient for forming a thin layer of the developer on the sleeve, the binding force between the developer carrier and the toner and the binding force between the carrier and the sleeve are weak. Even in such a case, the developer layer can be made extremely thin, so that the developer layer is sufficiently fixed to the sleeve.

In the present invention, the above-mentioned “thin layer” is desirably a thin developer layer having a thickness of 2000 μm or less, more preferably 1000 μm or less, further preferably 10 to 500 μm in the developing region, which is unprecedented. Due to the thin layer, the developer on the sleeve is not in contact with the image bearing member under an oscillating electric field, but the image bearing member (hereinafter, also referred to as an image forming member).
It is possible to develop by reducing the distance between the sleeve and the sleeve.

Here, the developing area is an area where the toner conveyed by the sleeve can be transferred to the image forming body by receiving an electrostatic force. The closest distance between the image forming body and the sleeve in that area is called a developing gap.

In the present invention, even if the toner in the thin layer on the sleeve is lost by development, if sufficient toner is immediately supplied to the thin layer, the developability is not affected. For this purpose, it is preferable to rotate the magnet in the sleeve at a high speed.

Next, in order to develop the small amount of developer conveyed to the developing area with maximum efficiency, (1) high speed rotation of the magnetic roll (2) application of an AC bias to the sleeve (3) image forming body and sleeve It is preferable to take measures such as reducing the gap between and.

In the non-contact developing method preferably adopted in the present invention, the gap between the image forming body and the sleeve can be reduced by thinning the developer layer, and the developing bias required to form the oscillating electric field required for flying the toner. The voltage of can be lowered. Therefore, the toner scattering is reduced in this respect as well, and there is an advantage that the leak discharge from the sleeve surface based on the developing bias is controlled. Furthermore, when the gap between the image forming body and the sleeve is reduced, the electric field strength formed in the developing region by the latent image is further increased, and as a result, even slight changes in gradation and fine patterns can be well developed. Like

Regarding the ratio of the toner to the carrier in the developer, the ratio of the total surface area of the toner to the carrier in a unit volume is preferably 0.5 to 2.

By setting the above conditions, the toner in the thin layer can be efficiently developed, the developability is stable, and good image quality can be obtained.

As a means for forming the thin developer layer, for example,
Any of the conventionally known layer thickness regulating members, such as a magnetic regulation plate preferably arranged with a certain gap from the sleeve, a magnetic rod arranged in proximity to the sleeve to regulate the developer layer thickness by a rotating magnetic field, etc. Is used. Above all, in order to eliminate impurities such as dust, fibers, paper powder or toner or carrier aggregates contained in the developer, a thin layer forming member including a pressure contact plate elastically and lightly pressed against the sleeve is provided. It is preferably used.

This thin layer forming member is an elastic plate that directs the tip of the sleeve toward the direction in which the rotation of the sleeve is reached, presses the sleeve with the belly of the member, and regulates the amount of developer that comes in at the gap between the tip edge and the sleeve surface. A thin layer is formed by allowing the developer to pass through between the sleeve and the elastic plate.

FIG. 3 shows the relationship between the gap (= opening area) between the tip of the elastic plate and the sleeve and the amount of developer adhering to the sleeve. From this figure, it can be seen that when the gap exceeds a certain value, the amount of developer on the sleeve is stable against these changes. In this stable state, the toner necessary for the development described above can be sufficiently transported.

Therefore, if the gap between the tips is 0.08 mm or more, it is possible to stably convey a certain amount of toner against variations in mounting accuracy and mechanical accuracy. Furthermore, the gap between the tips is 0.1 m
When it is at least m, stability is increased, which is preferable.

Of course, it is not desirable to make the gap at the tip too large, and if the gap is 5 mm or more, the uniformity of the layer is lost.

FIG. 1 shows a sectional view of a developing device suitable for carrying out the developing method of the present invention. In the figure, 20 is an image forming body, 2 is a housing, 3 is a sleeve, 4 is a magnetic roll having N and S8 poles, 5 is a thin layer forming member, 6 is a fixing member for the member, 7 is a first stirring member, 8 Is a second stirring member. Reference numerals 9 and 10 denote rotation axis directions of the stirring members 7 and 8, 11 denotes a replenishment toner container,
12 is a toner replenishing roller, 13 is a developer reservoir, 14 is a developing bias power source, 15 is a developing area, T is toner, and D is a developer. In such a developing device, the developer D in the developer reservoir 13 is sufficiently stirred and mixed by the first stirring member 7 rotating in the direction of the arrow and the second stirring member 8 rotating so as to overlap each other in the opposite direction. By the conveying force of the sleeve 3 rotating in the direction of the arrow and the magnetic roll 4 rotating in the opposite direction, it is attached and conveyed to the surface of the sleeve 3. The thin layer forming member 5 held by the fixing member 6 extending from the housing 2 is pressed against the surface of the sleeve 3 at the surface near the end, and the developer D conveyed as described above.
Regulate the layer thickness of. This developer layer develops a latent image on the image forming body 20 rotating in the direction of the arrow in the developing area 15 in a non-contact manner with a gap therebetween to form a toner image. At the time of development, a developing bias including an AC component is supplied from the power source 14 to the sleeve 3 described above.
As a result, only the toner in the developer is selectively transferred to the surface of the latent image and is adhered onto the surface of the souve 3. The layer thickness of the developer can be measured, for example, as follows. That is, the layer thickness can be obtained by comparing the position of the projected image of the screen of the sleeve with the position of the projected image of the thin layer formed on the sleeve using a Nikon profile projector manufactured by Nihon Kogaku Co., Ltd.

The thin layer forming member 5 has one end fixed by a fixing member 6 to give elasticity, for example, a magnetic or non-magnetic metal,
It is a thin plate made of a metal compound, plastic, rubber, etc. that is extremely uniformly formed and has a thickness of 50 to 500 μm.

As described above, the sleeve 3 is elastically pressed by the portion of the surface close to the other end of the thin layer forming member whose one end is fixed.
The carrier amount is regulated by passing the carriers preferably one by one at the contact position of the thin plate. Impurities in the developer D, aggregates of the carrier or toner, etc. cannot pass through the regulation position. Therefore, it is possible to obtain a uniform and stable developer layer reaching the developing region 15 by always making it thin.

In the developing method of the present invention, when a resin-coated carrier is used, even a small particle size carrier has good fluidity, so that even if the layer thickness is regulated by the thin layer forming member, uniform development on the sleeve is achieved. The agent layer can be formed, the releasability is good, and the filming of the toner on the carrier does not occur even when a strong pressure is applied.

The amount of the developer conveyed to the developing area 15 is controlled by changing the pressing force and the contact angle of the thin layer forming member 5 with respect to the sleeve 3.

It is advantageous that the carrier and the toner constituting the developer have small particle diameters in terms of image resolution and gradation reproducibility. For example, even when the toner particle size of the developer layer is 5 μm or less and the carrier particle size is 50 μm or less, and even 30 μm or less, by using a means such as the thin layer forming member 5 described above, It is possible to automatically remove the impurities, agglomerates, and the like to form a uniform thin layer. Further, even when the particle size is as small as that of the carrier toner, the mixing of impurities is eliminated and a uniform thin layer can be formed.

On the contrary, in order to prevent the carrier from being attached to the image forming body, it is preferable that the carrier particle size is large because a strong magnetic force is received. For example, even if the carrier particle diameter is about 50 to 100 μm, a uniform thin layer can be formed by the above method. In addition,
When the carrier particle size becomes large, the height of the carrier in the thin layer becomes large and the layer becomes rough, so that the developability is deteriorated. From this point, the carrier has a small particle size and a magnetization of, for example, 10 to 20.
0, preferably 20 to 100, more preferably 20 to 50 emu / g is desirable. If the magnetization is less than 10 emu / g, a predetermined magnetic brass cannot be formed, and if it exceeds 200 emu / g, the magnetization is too large to perform good development under an oscillating electric field, and a good image cannot be obtained.

The developer D, which is sufficiently stirred in the developing device and is imparted with desired triboelectrification, is regulated by the thin layer forming member 5 in the process of being attached and conveyed onto the sleeve 3 to form an extremely thin and uniform developer layer. To be done. This developer layer is sleeve 3
Is conveyed in one direction by rotation of the magnetic roll 4
Rotation in the opposite direction causes a magnetic bias having an oscillating component to make a complicated motion such as rolling on the sleeve 3, so that the latent image of the image forming body 20 is reached in a non-contact manner by reaching the developing region 15. When developing, the toner is effectively supplied toward the latent image surface. Since the developer layer can be formed as a very thin layer of 500 μm to 10 μm as described above, non-contact development can be performed even if the gap between the image forming body 20 and the sleeve 3, that is, the developing gap is narrowed to, for example, 500 μm. Is fully possible. When the developing gap is narrowed in this way, the electric field in the developing region 15 increases, so that there is an advantage that sufficient developing is achieved even if the developing bias applied to the sleeve 3 is small, and leak discharge of the developing bias is reduced. Furthermore, since the contrast of the latent image is increased, the resolution and other image quality of the image obtained by development are generally improved.

Further, as an effect of the desirable mode of the present invention, since the developing method is non-contact development and only the toner is selectively scattered and developed toward the latent image surface, the carrier adhesion to the latent image surface is prevented. To be done. Further, since the latent image surface is not rubbed, the surface of the image forming body is not damaged, and no blemishes are formed.
The resolution and gradation reproducibility are good, and a sufficient amount of toner can be attached to the latent image surface. Furthermore, it is suitable for multicolor development because it can be developed over an image forming body on which a toner image is formed.

The stable developing condition in the developing method of the present invention is 10 to 1000 μm for the developer layer, more preferably 500 μm.
The development gap is 200 μm to 2000 μm, and the rotation speed of the sleeve 3 and the rotation speed of the image forming body 20 are determined by experiments so as to optimize the toner adhesion amount on the sleeve.

Next, the constitution of the developer applied to the developing method of the present invention is as follows.

As the resin contained in the toner applied to the developing method of the present invention, a resin obtained by reacting a polyvalent metal compound with a carboxy group present in the polymer component is used.

The resin contained in the toner has a molecular weight distribution divided into at least two groups of at least a low molecular weight polymer component and a high molecular weight polymer component, and has a low molecular weight in a molecular weight distribution curve measured by gel permeation chromatography (GPC). The maximum value of the polymer component is 1 × 10 ³ to 2 × 10 ⁴ ,
It is preferred that the high molecular weight polymer component have at least two local maxima between 1x10 ^{5 and} 2x10 ⁶ .

With such a design, fixing can be performed at a lower temperature, and the elastic modulus at the time of melting can be increased to further improve the offset resistance, and at the same time, the blocking resistance is also good. can do. Further, the resin can be made tougher by the ionic bond and the high molecular weight polymer component, and the generation of fine particles due to the collision with the sleeve or the photoconductor can be suppressed to prevent the sleeve or the photoconductor surface from being contaminated.

When introducing the carboxy group for reacting with the polyvalent metal compound to form an ionic bond, it is sufficient that at least the carboxy group is introduced into the low molecular weight polymer component.
Since the fine particles generated from the toner component due to the collision with the sleeve or the surface of the photoconductor are mainly due to the relatively fragile component having a low molecular weight, such a low molecular weight component is crosslinked by at least a metal ion bond to obtain a toughness. By doing so, generation of fine powder, which is a factor of filming, can be suppressed.

As the monomer for obtaining the polymer of the toner main component resin, at least one selected from styrene-based monomers, ester-based monomers such as acrylic acid and methacrylic acid is used as an essential component. It is preferable that they are united. Further, in order to obtain a polymer having a carboxy group, a monomer selected from acrylic acid (including methacrylic acid and the like) and its derivative may be copolymerized in addition to the above-mentioned monomer. The preferred monomer having a carboxy group is a half-ester compound having a structure obtained by an esterification reaction of a hydroxyl group-containing acrylic acid ester, methacrylic acid ester and its derivative with a dicarboxylic acid compound.

When a carboxy group is introduced at a position near the end of the main chain as described above, the steric hindrance of the chemical structure is reduced and the reaction with the polyvalent metal compound proceeds efficiently to suppress the residue of the hydrophilic carboxy group. It is possible to generate an effective ionic bond for achieving the object of the present invention, and to have a good crosslinked structure and hydrophobicity.

Examples of the styrene-based monomer include styrene and o-
Methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-ethylstyrene, 2,3
-Dimethylstyrene, 2,4-dimethylstyrene, pn
-Butylstyrene, p-tert-butylstyrene, pn
-Hexyl styrene, pn-octyl styrene, p-
n-nonylstyrene, pn-decylstyrene, pn
-Dodecylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene and the like can be mentioned. Of these, styrene is particularly preferable.

The toner resin must have appropriate pulverizability during toner production, and the content of the styrene component in the copolymer must be
If the amount is 30% by weight or less, the pulverizability tends to decrease, so the content is usually 30% by weight or more, preferably 40% by weight or more, and the upper limit is generally preferably 95% by weight.

Examples of the acrylic acid ester and methacrylic acid ester include methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-octyl acrylate, dodecyl acrylate, lauryl acrylate, acrylic acid. Acrylic esters such as 2-ethylhexyl, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, and methyl α-chloroacrylate; methyl methacrylate,
Ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylamino methacrylate. Examples thereof include methacrylic acid esters such as ethyl and diethylaminoethyl methacrylate.

Examples of the carboxy group-containing compound forming the half-ester compound include malonic acid, succinic acid, and aliphatic dicarboxylic acid compounds such as glutaric acid or aromatic dicarboxylic acid compounds such as phthalic acid, and acrylic acid having a hydroxyl group or A half-ester compound can be obtained by an esterification reaction with a derivative of methacrylic acid.

The dicarboxylic acid compound may have a hydrogen atom substituted with a halogen group element, a lower alkyl group, an alkoxy group, or the like, or may be an acid anhydride.

The hydroxyl group-containing acrylic acid or methacrylic acid derivative may be acrylic acid or methacrylic acid to which 1 mol or 2 mol or more of alkylene oxide such as ethylene oxide or propylene oxide is added, or acrylic acid or methacrylic acid. It may be a hydroxyalkyl ester obtained by esterifying a dihydric alcohol such as propylene glycol.

The preferable half-ester compound can be represented by the following general formula (A).

In the general formula (A), L represents a divalent bonding group having an ester bond in the molecular chain and having 3 or more carbon atoms, and may have a substituent. R ₁ represents a hydrogen atom or a methyl group.

More preferable compounds can be represented by the following formulas (1) to (4).

In the formula, R ₂ and R ₃ represent a hydrogen atom or a methyl group, m represents 1 to 14 and n represents 0 to 8.

In the formula, R ₄ and R ₅ are H or CH ₃ , and h is an integer of 1 to 14, and X is
Represents a hydrogen atom, a halogen group element, a lower alkyl group or an alkoxy group.

In the formula, R ₆ is H or CH ₃ , j is an integer of 3 to 6, and k is an integer of 0 to 8.

In the formula, R ₇ is H or CH ₃ , l is an integer of 3 to 6, Y is H, a halogen group element, a lower alkyl group or an alkoxy group.

Among the half-ester compounds represented by the formulas (1) to (4), the compound represented by the formula (1) is preferable.

Examples of the half-ester compound represented by the formula (1) include succinic acid mono (meth) acryloyloxyethyl ester, succinic acid mono (meth) acryloyloxypropyl ester, glutaric acid mono (meth) acryloyloxyethyl ester, and phthalic acid. Examples thereof include mono (meth) acryloyloxyethyl ester and phthalic acid mono (meth) acryloyloxypropyl ester.

The styrene-based monomer, acrylic acid ester-based monomer,
A polymer obtained from a methacrylic acid ester-based monomer and a half-ester compound obtained by an esterification reaction of an acrylic acid or a methacrylic acid-based derivative having a hydroxyl group and a dicarboxylic acid compound has a content ratio of the monomer unit. The styrene-based monomer is 30 to 95% by weight, preferably 40 to 95% by weight, and the acrylate or methacrylic acid ester monomer is 70 to 5% by weight, preferably 5 to Desirably, it is 50% by weight, and the half-ester compound is 0.5 to 30% by weight, preferably 1 to 20% by weight.

When the content of the acrylic acid ester-based monomer or the methacrylic acid ester-based monomer is more than 70% by weight, or the content of the half-ester compound is less than 0.5% by weight, the resistance to high-temperature fixing is high. The offset property may be deteriorated, and the blocking resistance and the plasticizer resistance may be deteriorated.

The resin contained in the toner of the present invention contains a resin obtained by reacting the above-mentioned polymer having a carboxy group with a polyvalent metal compound as a component.

The metal element in the polyvalent metal compound, Cu, Ag,
Be, Mg, Ca, Sr, Ba, Zn, Cd, Al, Ti, Ge, Sn, V, Cr, Mo, Mn, Fe, Ni,
Co, Zr, Se, etc. are mentioned.

Among these various elements, alkaline earth metals (Be, Mg,
Ca, Sr, Ba) and zinc group elements (Zn, Cd) are preferable, and Mg and Zn are particularly preferable.

Examples of these polyvalent metal compounds include fluorides, chlorides, chlorates, bromides, iodides, oxides, hydroxides, sulfides, sulfites, sulfates, selenides and tellurides of the above-mentioned various elements. , Nitrides, nitrates, phosphides, phosphinates, phosphates, carbonates, orthosilicates, acetates,
Examples thereof include lower alkyl metal compounds such as oxalates, methylated products and ethylated products.

Of these, acetates and oxides are preferable.

The amount of the polyvalent metal compound added cannot be unequivocally varied depending on the type and amount of the monomer constituting the polymer, but for example, the polymer is the styrene monomer,
When the low molecular weight polymer component and the high molecular weight polymer component are composed of the (meth) acrylic acid ester-based monomer and the half ester compound, 0.1 to 1 mol per 1 mol of the half ester compound charged. Is enough.

To react the polyvalent metal compound with the polymer,
For example, a solution containing the polymer obtained by polymerization by a solution polymerization method is mixed with a solution in which the metal compound or the metal compound is dispersed, and the solvent is removed by heating for about 1 to 3 hours, It is advisable to maintain the temperature in the system at about 150 to 180 ° C. for 1 hour or more to complete the reaction. In some cases, the metal compound may be allowed to be present in the reaction system together with a solvent before starting the polymerization, and the polymer obtained as a desolvent and the polyvalent metal compound are roll mills, kneaders, and extruders. You may melt-knead using a.

The resin thus obtained by reacting the polymer and the polyvalent metal compound thus obtained has an ionic bond between the carboxy group and the metal atom contained in the polymer component, and a kind of cross-linked structure due to this ionic bond. Is appearing. This ionic bond is a much slower bond than a covalent bond or the like.

In the polymer molecular weight distribution of the toner main component resin, when the maximum value of the molecular weight distribution of the low molecular weight polymer component is smaller than the above range, the blocking resistance may be deteriorated, and when it is larger than the above range, the fixability may be deteriorated. May worsen. Further, when the maximum value of the molecular weight distribution of the high molecular weight polymer component is smaller than the above range, the offset resistance, durability, and high temperature and humidity resistance may be deteriorated, and when it is larger than the above range, the fixing property is deteriorated. Sometimes.

Further, from the viewpoint of molecular weight distribution, the molecular weight distribution of a polymer composed of a low molecular weight polymer component and a high molecular weight polymer component is as follows: weight average molecular weight (Mw) / number average molecular weight (Mn)
The value of (hereinafter referred to as Mw / Mn) is 3.5 or more, preferably 4.
It is preferably 0 to 40.

In the resin having a bimodal distribution in the low molecular weight portion and the high molecular weight portion, the content of the high molecular weight polymer component is preferably 15% or more, and particularly preferably 15 to 50% by weight of the whole resin. When the content of the high molecular weight polymer component is less than 15% by weight, offset resistance and durability may be deteriorated.

The resin in the present invention may be produced by any production method as long as it has the above-mentioned molecular weight bimodal distribution. For example, a first-stage polymerization in which either one of a high molecular weight polymer component and a low molecular weight polymer component is first produced by polymerization is carried out, and then the produced one polymer component is treated with the other one. It is possible to obtain a polymer having a bimodal molecular weight distribution by dissolving it in a monomer that gives a polymer constituting the polymer component and carrying out the second-stage polymerization to produce the other polymer component. it can.
As described above, the polymer obtained by the two-stage polymerization is presumed to be a mixture of the low molecular weight polymer component and the high molecular weight polymer component uniformly at the molecular level.

This two-stage polymerization can be carried out by, for example, a solution polymerization method, a suspension polymerization method, an emulsion polymerization method, etc. Among them, the solution polymerization method is preferable.

On the other hand, a polymer having a bimodal molecular weight can be obtained by mixing a low molecular weight polymer component and a high molecular weight polymer component. Since the polymer may not be uniformly mixed at the molecular level, the polymer obtained in the above two-stage polymerization method is particularly preferable as the polymer in the present invention.

Further, the toner resin in the present invention has a glass transition point
50 to 80 ° C., the glass transition point of the low molecular weight polymer component is 50 ° C. or higher, preferably 55 ° C. or higher, and the high molecular weight polymer component is 65 ° C. or lower, preferably 60 ° C. or lower. It is desirable to have. This is because blocking resistance can be improved by adjusting the glass transition point. The glass transition point can be easily adjusted by appropriately selecting the type of monomer.

Furthermore, the toner resin of the present invention may contain a monomer unit such as vinyl acetate, vinyl propionate, vinyl chloride or ethylene in its molecular chain within a range not impairing the object of the present invention. The polymer of the monomer may be blended. Moreover, a polyester resin or an epoxy resin may be contained.

The toner of the present invention contains a colorant in the above-mentioned specific resin, but may further contain a magnetic material and a property improving agent in the resin, if necessary.

As a colorant, carbon black, nigrosine dye (CINo.50415B), aniline blue (CINo.5040)
5), Calco Oil Blue (CINo.azoic Blue3), Chrome Yellow (CINo.14090), Ultramarine Blue (CINo.77103), DuPont Oil Red (CINo.261)
05), Quinoline Yellow (CINo.47005), Methylene Blue Chloride (CINo.52015), Phthalocyanine Blue (CINo.74160), Malachite Green Oxalate (CINo.42000), Lamp Black (CINo.77266),
Rose Bengal (CI No.45435), mixtures thereof, and the like can be mentioned. These colorants need to be contained in a sufficient ratio to form a visible image with a sufficient density, and are usually about 1 to 20 parts by weight with respect to 100 parts by weight of the resin.

Examples of the magnetic material include ferrite, magnetite and other iron, cobalt, nickel, and other ferromagnets or alloys, compounds containing these elements, or ferromagnetic materials that do not contain ferromagnetic elements Mention may be made of alloys which become ferromagnetic, for example manganese-copper-aluminum, manganese-copper-tin and other types of alloys called Heusler alloys containing manganese and copper, or chromium dioxide. These magnetic materials are uniformly dispersed in the resin in the form of fine powder having an average particle size of 0.1 to 1 micron. The content is 20 to 70 parts by weight, preferably 40 to 70 parts by weight, per 100 parts by weight of the toner.

Examples of the property improver include fixability improver, charge control agent,
There are others.

Examples of the fixability improver include polyolefin, fatty acid metal salt, fatty acid ester and fatty acid ester wax, partially saponified fatty acid ester, higher fatty acid, higher alcohol, liquid or solid paraffin wax, polyamide wax, polyhydric alcohol ester, silicone. Varnish, aliphatic fluorocarbon, etc. can be used.
A wax having a softening point (returning ball method JIS K2531) of 60 to 150 ° C. is particularly preferable.

As the charge control agent, conventionally known ones can be used, and examples thereof include nigrosine dyes and metal-containing dyes.

Further, the toner of the present invention is preferably used by mixing inorganic fine particles such as a fluidity improver.

The inorganic fine particles used in the present invention have a primary particle diameter of 5 mμ to 2 μ, and preferably 5 mμ to 500 mμ.
Is a particle. The specific surface area by BET method is 20-500
It is preferably m ² / g. The ratio mixed with the toner
It is 0.01 to 5 wt%, preferably 0.01 to 2.0 wt%. Examples of such inorganic fine powders include silica fine powder, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, silica sand, clay, mica, diatomaceous earth, and chromium oxide. , Cerium oxide, red iron oxide, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, silicon nitride, etc., but silica fine powder is particularly preferable.

The silica fine powder mentioned here is a fine powder having a Si—O—Si bond, and includes both those produced by the dry method and the wet method. In addition to anhydrous silicon dioxide, any of aluminum silicate, sodium silicate, potassium silicate, magnesium silicate, zinc silicate, and the like may be used, but those containing 85% by weight or more of SiO ₂ are preferable.

Specific examples of these silica fine powders include various commercially available silicas, but those having a hydrophobic group on the surface are preferable, for example, AEROSIL R-972, R-974, R-805, R-812 (above Aerosil Co., Ltd. Manufactured by Tarcox) (manufactured by Tarco) and the like. In addition, silane coupling agents, titanium coupling agents, silicone oil, silica fine powder treated with silicone oil having amine in the side chain, and the like can be used.

To give an example of a suitable method for producing a toner according to the present invention, first, a binder resin or one obtained by adding a toner component such as a colorant, if necessary, to
It is possible to obtain a toner having a desired particle diameter by melt-kneading with an extruder, cooling and then finely pulverizing with a jet mill or the like, and classifying this. Alternatively, a toner having a desired particle diameter can be obtained by spraying a product melted and kneaded with an extruder in a molten state with a spray dryer or the like and dispersing it in a liquid.

As the image forming method of the present invention, a developer is prepared by using the above-mentioned specific toner, a latent image is formed and developed by using the developer, and the obtained toner image is transferred. The upper roller, which is electrostatically transferred onto the paper, is fixed by a heating roller fixing device in which the temperature of the upper heating roller is set to a constant temperature to form a copied image.

The toner according to the present invention is preferably used for fixing such that the contact time between the toner on the transfer paper and the heating roller is within 1 second, particularly within 0.5 second.

The resin of the resin-coated carrier used in the present invention is preferably a resin containing a copolymer obtained by polymerizing a styrene monomer and an acrylic monomer. Further, fluororesin, silicone resin, etc. are also used.
The styrene-based monomer and the acrylic-based monomer may be the same as the binder component of the toner.

A styrene-methyl methacrylate copolymer is particularly preferable.

The copolymer is usually used, emulsion polymerization, bulk polymerization,
It can be produced by suspension polymerization or solution polymerization.

The average film thickness of the resin to be coated is 0.1 to 10 μm, preferably 0.3 to 4 μm, more preferably 0.3 to 2.0 μm. If it is less than 0.1 μm, the insulating property is poor and good developability is difficult to obtain, and if it exceeds 4 μm, particularly 10 μm, the carrier magnetization becomes too small and carrier adhesion easily occurs.

The magnetic material of the resin-coated carrier in the present invention includes substances that are strongly magnetized in that direction by a magnetic field, for example, ferrite, magnetite, and other metals exhibiting ferromagnetism such as iron, nickel and cobalt, or these metals. Alloys or compounds, alloys that do not contain ferromagnetic elements, but become ferromagnetic by proper heat treatment, for example, alloys of the type called Heusler alloys such as manganese-copper-aluminum or manganese-copper-tin, or chromium dioxide. Etc. can be used. Here, ferrite is a generic term for magnetic oxides containing iron, and is not limited to spinel ferrites represented by the chemical formula of MO.Fe ₂ O ₃ (M is a divalent metal). Ferrite is particularly preferable for obtaining a carrier suitable for the purpose of the present invention because various magnetic properties can be obtained by changing the composition of the contained metal component.

Since ferrite is an oxide, its specific gravity is smaller and lighter than metal powder such as iron powder or nickel powder,
It is suitable for facilitating the mixing and stirring with the toner and realizing a uniform toner concentration and charge amount. Moreover, since ferrite has a higher electric resistance than iron powder, nickel powder, cobalt powder, etc. (10 ⁸ to 10 ¹² Ω · cm), even if the surface resin insulating layer is a thin film of about 0.5 μm, It has an advantage that an insulating carrier that can be sufficiently used in a developing method in which a high bias electric field is applied to the developing gap can be realized.

Since the electric resistance of ferrite alone is at most about 10 ¹² Ω ・ cm even if it is the highest, electric charges may be induced to the leading edge of the carrier under an alternating electric field.
It is preferable to have a high insulating property (10 ¹⁴ Ω · cm or more), and it is necessary to coat the ferrite surface with a resin for stable development.

The ferrite preferably has a saturation magnetization of 10 to 40 emu / g and a coercive force of 0.1 to 100 Oe under an external magnetic field of 1000 Oe, a resistivity of 1 × 10 ⁶ to 1 × 10 ¹¹ Ω · cm, and a specific gravity of
It is preferably 4.0 to 5.5 and the porosity is 1.0 to 10%.

The method for producing a resin-coated carrier used in the present invention is a coating solution prepared by dissolving a coating resin and other resin components added as necessary in an organic solvent to prepare a coating solution, for example, a coating layer on the carrier surface by a spray drying method. Can be formed. Alternatively, for example, in a fluidized bed apparatus, the magnetic particles of the carrier are raised to an equilibrium height by an ascending pressurized gas flow, and the coating liquid is spray-applied by the time the magnetic particles fall again. This coating can be repeated to form a coating layer.

In the present invention, in order to obtain a more preferable image, the toner particle size (volume average) is preferably less than 20 μm, and particularly preferably in the range of 15 to 1 μm.

When it exceeds 15 μm, it is difficult to obtain high resolution and excellent gradation reproducibility, and particularly when the thickness is 20 μm or more, the resolution of fine characters decreases. If it is less than 1 μm, fogging and toner scattering occur and a clear image cannot be obtained.

The resin-coated carrier in the present invention preferably has a spherical shape and has a volume average particle diameter of 100 μm or less, particularly 5 μm or more and 50 μm or less, in order to improve resolution and gradation reproducibility. Here, the carrier particle size is 50 μm, especially 100
When the thickness exceeds μm, the thinning of the developer layer is hindered, the developability deteriorates, and the image quality deteriorates. On the other hand, if it is less than 5 μm, the developing property of the developer, the triboelectric charging property, the fluidity, etc. are deteriorated, and the carrier is easily scattered.

The carrier resistivity is 10 ⁸ Ω ・ cm to prevent carriers from being injected by the bias voltage and adhering to the surface of the photoconductor, or from disappearing the charges that form the latent image.
Or more, preferably 10 ¹³ Ωcm or more, more preferably 10 ¹⁴
Insulating material with Ω · cm or more is preferable.

It is preferable to mix the above-mentioned toner and carrier in a ratio such that the total surface areas are equal, and the toner concentration (weight ratio of the toner to the developer) is set to 5 to 40 wl%, preferably 8 to 25 wl%. Is appropriate.

(Examples) Hereinafter, the present invention will be specifically described with reference to Examples.

FIG. 2 is a cross-sectional view showing the structure of the image forming apparatus used. When the document table is moved, the document image illuminated by the illumination light source 21 is illuminated on the image forming body 20 via the mirror 22 and the lens 23. To be done. In this way, an electrostatic latent image is formed. This electrostatic latent image is developed by the developing device A.

The toner image thus obtained is neutralized by the exposure lamp 28 to facilitate transfer, and then transferred to the recording paper P by the transfer pole 29. The recording paper P is separated from the image forming body by the separating electrode 30 and fixed by the fixing device 31. On the other hand, the image forming body 20 is cleaned by the removing electrode 32 and the cleaning device 33.

The cleaning device 33 has a cleaning blade 34. A roller 36 collects the toner scraped by the blade 34.

In the image forming process by the copying machine shown in FIG. 2, development is performed using a developer having the following formulation, and image formation is performed under the image forming conditions shown in Table 3. : Preparation of developer: (1) Preparation of toner (1) -1 Synthesis of toner main component resin Synthesis example 1 400 ml of toluene was placed in a separable flask of 2 l, and the air in the flask was replaced with nitrogen.

Then, the toluene in the flask was heated to reflux it.

Next, 240 g of styrene, 60 g of n-butyl acrylate and 0.6 g of benzoyl peroxide were placed in the flask, and the first stage polymerization reaction was carried out for 12 hours under reflux to produce a high molecular weight polymer component.

After 12 hours, styrene 490 was added to the flask.
g, n-butyl acrylate 140 g, monoacryloyloxyethyl succinate 70 g and benzoyl peroxide 35 g
The second step of the polymerization reaction was carried out while the mixture of was added dropwise over 2 hours.

After the dropping of the mixture, the second-stage polymerization reaction was continued at reflux temperature for an additional 1 hour to produce a low-molecular weight polymer component. Then, zinc oxide 10 in the flask.
g was added and stirred for 1 hour.

Then, the solvent toluene was distilled off under reduced pressure to obtain a resin A which was a reaction product of a polymer having a carboxyl group-containing side chain and zinc oxide.

The molecular weight distribution of this resin A is HLC-802U manufactured by Toyo Soda Co., Ltd.
When measured with R, this resin A shows 3.2 × 10 ⁵ and 9.5 × 10 ^5.
It had a maximum at ³ and a bimodal distribution in terms of molecular weight. The weight average molecular weight Mw was 121,000 and Mw / Mn was 12.5.

Synthesis Examples-2 to 4 Resins B to D were obtained in the same manner as in Synthesis Example-1 except that the composition of Synthesis Example-1 was changed to the composition of Table 1.

Comparative Synthesis Example-1 A resin E was prepared in the same manner as in Synthesis Example-1 except that zinc oxide was removed.

The properties of the resins A to E are shown in Table 2.

Comparative Synthesis Example-2 400 g of toluene was placed in a 2 l separable flask, air was replaced with nitrogen gas, and then 750 g of styrene and n-butyl acrylate 2 were added while heating and stirring the system to the boiling point of toluene.
00g, succinic acid monoacryloyloxyethyl ester 5
Solution polymerization was carried out while dropwise adding a mixture in which 0 g and 10 g of benzoyl peroxide as a polymerization initiator were dissolved over 2.5 hours.

After the addition of the mixture was completed, the mixture was aged for 1 hour while stirring at the boiling point of toluene, and 14.1 g of zinc oxide was added.

Next, the temperature of this system was gradually raised to 180 ° C. and the toluene was removed under reduced pressure to allow the reaction between the styrene-n-butyl acrylate-succinic acid monoacryloyloxyethyl ester copolymer and zinc oxide. A polymer under resin was obtained.

Comparative Synthesis Example-3 90 g of xylene was placed in a separable flask, further, 75 g of styrene, 20 g of butyl acrylate, 5 g of monobutyl maleate, 0.5 g of divinylbenzene were added, and the gas phase was kept at 80 ° C. after replacement with nitrogen gas, A solution obtained by dissolving 10 g of xylene and 1.2 g of benzoyl peroxide was added, and stirring was continued for 10 hours.
Then, the temperature was raised to 95 ° C. and maintained for 3 hours to complete the polymerization. After cooling, the polymerization solution was poured into a large amount of methanol, the precipitate was filtered off, and dried sufficiently at 50 ° C. Obtained Resin-G
Nw / Mn was 27 and Mw was 233,000.

(1) -2 Preparation of Toner 100 parts by weight of each of the resins A to D obtained in Synthesis Example-1 to Synthesis Example-4, 10 parts by weight of carbon black ("Mogal L", manufactured by Cabot Corporation), and polypropylene (Viscol)
660P, 2 parts by weight of Sanyo Chemical Industry Co., Ltd. and Wax-
2 parts by weight of E (manufactured by Hoechst Co.) was mixed with a Henschel mixer, then sufficiently kneaded with a two-roll mill at a temperature of 130 ° C., then allowed to cool, roughly crushed, and then crushed with a jet mill, Toner 1 according to the present invention having an average particle size of 11.0 μm after classification.
I got ~ 4. (Preparation of Comparative Toner) Comparative Toner (1) The Toner 1 except that a mixture of 100 parts by weight of Resin E and 10 parts by weight of carbon black (Mogal L Cabot) was used.
Comparative toner (1) was obtained in the same manner as above.

Comparative toner (2) 100 parts by weight of resin F and carbon black (Dia Black S
H: 5 parts by weight of Mitsubishi Kasei Co., Ltd.) was melt-kneaded, cooled, coarsely pulverized, and then finely pulverized with a jet mill to prepare a comparative toner (2) having an average particle size of about 13 to 15 μm.

Comparative Toner (3) Resin-G, 100 parts by weight, 5 parts by weight of zinc salt of di-t-butylsalicylic acid, 8 parts by weight of carbon black, metal salt dye (trade name: Sapon First Black B, CIAcod Blac
k, manufactured by BASF) 4 parts by weight were sufficiently melted and kneaded with a small pressure kneader. After cooling, the mixture was finely pulverized, and particles having a particle size of about 5 to 20 μm were selected as a comparative toner (3).

(2) Preparation of resin-coated carrier Carrier a: The monomer composition ratio of styrene and methyl methacrylate is 4
0:60 styrene-methyl methacrylate copolymer (Mw: 8
2,000, Mn: 25,000, Tg: 105 ℃) methyl ethyl ketone 30
A coating solution was prepared by dissolving it in 0 ml, and the coating solution
Zinc ferrite particles were coated with a Spiracoater (manufactured by Okada Seiko Co., Ltd.) to produce a carrier having a coating layer with a thickness of 1.0 μm. This is called "carrier a". The average particle size of this carrier a is 40 μm, the magnetization is 28 emu / g, and the specific resistance is 1
0 ¹⁴ Ω · cm or more.

Carrier b: Instead of the copolymer used for preparing the coating liquid in the carrier a, a styrene-methyl methacrylate copolymer having a monomer composition ratio of styrene and methyl methacrylate of 60:40 (Mw: 73,000, (Mn: 24,000, Tg: 98 ° C.) was used, and a carrier having a coating layer having an average film thickness of 0.8 μm was produced in the same manner as the carrier a except that copper / zinc ferrite particles were used. This is referred to as "carrier b". The average particle size of this carrier was 45 μm, the magnetization was 22 emu / g, and the specific resistance was 10 ¹⁴ Ω · cm or more.

Carrier c: Styrene and n instead of the copolymer used for carrier a
-Styrene-n-butyl acrylate copolymer having a monomer composition ratio of 90:10 with butyl acrylate (Mw: 93,000, M
"Carrier c" was produced in the same manner as Carrier a except that n: 37,000, Tg: 76 ° C) was used. Average particle size is 40μ
m, the magnetization was 28 emu / g.

Comparative carrier (a): The copper-zinc ferrite particles used in carrier a and having no resin coating layer were designated as "comparative carrier (a)".

Comparative carrier (b): Iron powder particles. EFV250 / 400 (made by Nippon Milling Co., Ltd.) was used as a comparative carrier (b).

(3) Preparation of developer Developer-1 toner 99.5 parts by weight and hydrophobic silica Aerosil R-97
(2, made by Aerosil Co., Ltd.) After mixing 0.5 parts by weight, the carrier
a 900 parts by weight was further mixed to obtain a developer-1 of the invention.

Developers 2 to 4 Toners 2 to 4 and hydrophobic silica were mixed in the same manner as in Developer 1 and then mixed with a carrier in a combination shown in Table 4 to obtain developers 2 to 4.

Comparative developer- (1) 10 parts by weight of the comparative toner (1) and 90 parts by weight of the comparative carrier (a) were mixed to obtain a comparative developer- (1).

Comparative developer- (2) 4 parts by weight of the comparative toner (2) and 96 parts by weight of the comparative carrier (b) were mixed to prepare a comparative developer- (2).

Comparative developer- (3) 10 parts by weight of the comparative toner (3) and 90 parts by weight of the comparative carrier (b) were mixed to obtain a comparative developer- (3).

(4) Actual shooting test Using the image forming apparatus having the requirements of Table 3 below, the developing conditions of Table 3 were applied using each of the developers, and Example 1 was performed.
4 and Comparative Examples (1) to (3) were taken. Table 3 Development conditions (Normal development) Image forming body Se photosensitive body (100φ drum) Linear velocity 100mm / s Surface potential + 800V (dark part) to 0V (light part) Sleeve diameter 25mm Sleeve linear velocity 250mm / s (forward direction) Magnetic Number of roll poles 8 poles Magnetic roll rotation speed 1200r.pm Development gap 500μm Developer layer thickness 400μm (maximum value) Developer toner concentration 12wt% Toner content in developer on sleeve 0.3mg / cm ² DC bias 0 to + 100V AC bias 0.5 to 2KVp-p (2KHz) After forming and developing an electrostatic charge image, transfer the obtained toner image onto a transfer paper and fix it with a heating roller fixing device. The minimum fixing temperature (minimum temperature of a heat roller capable of fixing) and the offset generation temperature (minimum temperature at which offset development occurs) were measured.

Minimum fixing temperature: After creating an unfixed image with the above copying machine, the surface layer is a heat roller having a diameter of 30φ formed of Teflon (polytetrafluoroethylene manufactured by DuPont) and the surface layer is a silicone rubber “KE-1300RTV” ( A toner image with sample toner transferred onto a transfer paper of 64 g / m ^{2 with} a fixing device consisting of a pressure roller formed by Shin-Etsu Chemical Co., Ltd., linear velocity 180 mm / sec,
Operation to fix with a linear pressure of 0.8 kg / cm and a nip width of 6.0 mm
The set temperature of the heat roller is increased stepwise by 5 ° C in the range of 100 to 230 ° C and repeated at each temperature, and the formed fixed image is rubbed with Kimwipe to show sufficient rubbing resistance. The lowest setting temperature for the fixed image was defined as the lowest fixing temperature. The fixing device used here does not have a silicone oil supply mechanism.

Offset generation temperature: The measurement of the offset generation temperature is similar to the measurement of the minimum fixing temperature, but after the unfixed image is created by the above copying machine, the toner image is transferred and the fixing process is performed by the above fixing device, and then Repeating the operation of sending a blank transfer sheet to the fixing device under the same conditions and visually observing whether or not toner stains occur on the fixing device while the set temperature of the heat roller of the fixing device is sequentially increased. The lowest preset temperature at which stains were generated due to the noise was defined as the offset generation temperature.

Further, the blocking resistance of the above toner was measured as follows.

Blocking resistance: The blocking resistance test was carried out by leaving it for 1 day under an environmental condition of a temperature of 55 ° C. and a relative humidity of 60% to examine whether or not aggregates were formed.

Next, normal temperature and humidity (20 ℃, 60% RH) and high temperature and humidity (30 ℃ 80%)
Under the (RH) environmental condition, a copying test was performed on 50,000 sheets and the following evaluation was performed.

Carrier adhesion: Judgment was made based on the number of carriers adhered on the copied image.

Fog: Evaluated by the relative density of the white background portion of the original density 0.0 to the developed image (white background reflection density was 0.0) (○) less than 0.01 (△) 0.01 to less than 0.03 (×) 0.03 or more Image loss and image unevenness: The copied image was visually evaluated at the end of the development process of 50,000 times.

Toner scattering: After completion of the development process of 50,000 times, the inside of the copying machine was observed and visually judged.

The results of the live-action test are listed in Table 4.

As can be seen from the above results, in the developing method using the developers 1 to 4 of the present invention, since it has a good charging property, it is possible to obtain 50,000 sheets under any environmental conditions of normal temperature and normal humidity and high temperature and high humidity. In the copy test, fog and carrier adhesion did not occur, and a uniform thin layer was formed, so that there was no image dropout or image unevenness, and the durability that a clear image with good resolution and gradation reproducibility was obtained was obtained. Good and little toner scattering.

The low temperature fixability, anti-offset property and blocking resistance were also good, and the fixable temperature range was wide.

On the other hand, in the developing method using the comparative developers (1) to (3), fogging and carrier adhesion are caused due to poor chargeability in a copying test of 50,000 sheets under normal temperature and normal humidity and high temperature and high humidity conditions. Since a large amount of toner was scattered and a uniform thin layer of the developer could not be formed, only an unclear image with a lack of image and image unevenness was obtained, and the durability and the temperature and humidity resistance were poor. In addition, the fixing temperature was high and the fixing temperature range was narrow.

Next, an actual shooting test was similarly conducted under the conditions shown in Table 5. Table 5 Development conditions (reverse development) Image-forming body Induced photoreceptor (140φ drum) Linear velocity 60mm / s Surface potential -700V (non-exposed area), -50V (exposed area) Sleeve diameter 20mm Sleeve linear velocity 250mm / s ( Forward direction) Number of magnetic roll poles 8 poles Magnetic roll rotation speed 1200r.pm Development gap 500μm Developer layer thickness 400μm (maximum) Developer toner concentration 12wt% Toner content in developer on sleeve 0.4mg / cm ² DC Bias -500 to -600V AC bias 0.5 to 2.5KVp-p (2KHz) In the developers 1 to 4 of the embodiment of the present invention, even when copying 50,000 sheets under normal temperature and normal humidity and high temperature and high humidity conditions,
No fogging, carrier adhesion, image bleeding, image unevenness, and toner scattering were obtained, and good results were obtained as in Table 3.

[Brief description of drawings]

FIG. 1 is a sectional view showing the structure of a developing device according to the present invention, and FIG. 2 is a sectional view showing the structure of an image forming device. FIG. 3 is a graph showing the relationship between the opening area of the thin layer forming member and the amount of developer in the developing device. 20 ... Image forming body, 15 ... Development area, 2 ... Housing,
3 ... Sleeve, 4 ... Magnetic roll, 5 ... Thin layer forming member, 28 ... Exposure lamp, 29 ... Transfer member, 30 ... Separation electrode,
31: fixing device, 32: removing electrode, 34: cleaning blade, A: developing device, T: toner, D: developer,
P: Recording paper.

 ─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-56-158340 (JP, A) JP-A-57-178250 (JP, A) JP-A-61-110155 (JP, A) JP-A-61- 110156 (JP, A) JP-A-60-131547 (JP, A)

Claims (2)

[Claims] 1. When an oscillating electric field is generated in a developing area to develop a latent image formed on an image carrier with a carrier and a toner-containing developer layer on a developer carrier, the developer layer is 10 to 1000 μm. The main component resin of the toner has a molecular weight distribution of at least two groups of a low molecular weight polymer component and a high molecular weight polymer component, and the molecular weight distribution is in a molecular weight distribution curve by gel permeation chromatography. The maximum value of the low molecular weight polymer component is 1 × 10 ³ to 2 × 10 ⁴ , the maximum value of the high molecular weight polymer component is 1 × 10 ⁵ to 2 × 10 ⁶ , and the main component resin Is a polyvalent metal salt of a polymer obtained from the following (a), (b) and (c): (A) Styrene-based monomer (b) Acrylic acid ester-based monomer or methacrylic acid ester-based monomer (c) Monomer represented by the following general formula (A): General formula (A) (In the formula, R ₁ represents a hydrogen atom or a methyl group, L represents a divalent linking group having 3 or more carbon atoms having an ester bond, and may have a substituent.) 2. The method for developing an electrostatic latent image according to claim 1, wherein the metal salt is a zinc group metal salt or an alkaline earth metal salt.