JPH0774916B2 - Electrostatic latent image developer - Google Patents

Description

TECHNICAL FIELD The present invention relates to a developer used for developing an electrostatic latent image formed in electrophotography, electrostatic printing, electrostatic recording or the like. In particular, the present invention relates to a two-component electrostatic latent image developer (hereinafter simply referred to as a developer) composed of toner particles and carrier particles, which is preferably used for heat roller fixing.

[Background of the Invention]

In electrophotography, an electrostatic latent image is usually formed by charging and exposing an electrostatic image carrier made of a photoconductive photoconductor, and the electrostatic latent image is then added to a binder made of a resin to form a colorant or the like. It is developed with a toner containing fine particles to form a fine image, and the obtained toner image is transferred to a support such as transfer paper and fixed to form a visible image.

As described above, it is necessary to fix the toner image in order to obtain a visible image, and in the past, a heat roller fixing method having high thermal efficiency and capable of high-speed fixing has been widely adopted.

However, 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 lower the temperature of the heat roller in order to reduce the size of the heater to enable continuous copying over a large number of times, and (e) increase the thermal stability. There is a strong demand for enabling the fixing process in this 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.

The developer is composed of a one-component developer containing a magnetic substance in the toner to impart magnetism to eliminate the need for a carrier, and a non-magnetic toner or a toner slightly imparted with magnetism and a carrier having magnetism. There are component developers,
The latter two-component developer is widely used because it is easy to control the triboelectric charge of the toner, has excellent developability, has good image quality, and can impart an arbitrary color to the toner. As such a two-component developer, a developer comprising an iron powder carrier and a toner has been conventionally known, but a developer using this iron powder carrier has an unstable triboelectrification property to the toner and is There is a drawback that fog occurs in the captured image.

That is, the toner substance is liable to adhere to the surface of the iron powder carrier particles during friction with the toner, which makes the carrier triboelectrification property further unstable, resulting in a decrease in image density,
Fog increases. Therefore, when images are continuously formed in the electrophotographic apparatus by the developer using the iron powder carrier, the developability deteriorates after a few times, and good image quality cannot be maintained. Such a phenomenon becomes more remarkable when the environmental conditions are high temperature and high humidity.

Further, when the toner is a developer that can be fixed at a low temperature, filming on the carrier causes defects in the durability and the image quality under high temperature and high humidity conditions.

Although various studies have been made in the past in order to solve the above-mentioned drawbacks, the present situation is that all of them cannot be satisfied.

For example, there is a proposal that a resin used for improving offset resistance is composed of a low molecular weight polymer component and a high molecular weight polymer component (Japanese Patent Laid-Open Nos. 56-158340, 56-16144 and 58-58). No. 202455). However, when a high molecular weight polymer component is introduced into the toner, the offset generation temperature becomes high, which is convenient for offset resistance, but at the same time, the fixing temperature becomes high, which causes a disadvantage in fixing at a lower temperature. On the contrary, if the glass transition point or softening point of the resin is lowered to enable the toner to be fixed at low temperature, not only the anti-offset property is deteriorated but also the blocking resistance is deteriorated and the toner particles are filled in the carrier particles. This gives rise to drawbacks such as lowering of durability due to filming and occurrence of filming on carrier particles or the surface of the photoconductor under high temperature and high humidity conditions.

Further, for example, in JP-A-57-178250, 61-110155 and 61-110156, a resin obtained by reacting a polymer having a carboxyl group with a metal compound provides anti-offset property and anti-blocking property. There is an attempt to widen the tolerance and fixing temperature allowable range, but the one-component developer or the two-component developer using the iron powder carrier disclosed in the above publication has unstable triboelectrification under high temperature and high humidity conditions, Further, filming easily occurs on the carrier particles and the photosensitive surface, and cleaning failure occurs due to fusion with the cleaning blade, resulting in deterioration of the durability because a good image cannot be obtained continuously.

[Object of the Invention]

An object of the present invention is to solve the above problems and to provide a developer having good offset resistance and capable of being fixed at a lower temperature.

Another object of the present invention is to provide a developer having good blocking resistance.

Another object of the present invention is to have stable triboelectric charging properties,
It is to provide a developer having good durability, which can stably obtain a good image.

Furthermore, the object of the present invention is to prevent filming on carrier particles, the surface of a photoreceptor and a cleaning blade even under high temperature and high humidity environmental conditions, and to obtain a stable image even when used many times. It is to provide a developer having good properties.

[Structure of Invention]

The above-mentioned object of the present invention is to coat toner particles (A) containing a resin as a main component with a resin obtained by reacting a carboxyl group present in a polymer component with a polyvalent metal compound, and a magnetic material surface coated with the resin. This is achieved by an electrostatic latent image developer containing resin-coated carrier particles (B).

According to the developer having such a constitution, the resin as the main component of the toner exhibits a crosslinked structure due to the ionic bond between the carboxy group and the metal atom in the polymer component. And then they are much loosely coupled. Therefore, even if the content of the low molecular weight polymer component in the resin is increased, offset resistance and blocking resistance do not deteriorate due to crosslinking by ionic bonds, and since it is due to gradual ionic bonds, it differs from crosslinking by covalent bonds. Then, the properties of the low molecular weight polymer component are reflected, and the fixability is also improved. Further, by containing an ionic cross-linked structure and a high molecular weight polymer component, it becomes a tough resin, and the filming property that a part of the toner component is transferred due to collision with carrier particles or the surface of the photoreceptor is suppressed and durability is improved. improves.

However, the above toner alone cannot satisfy all the characteristics under high temperature and high humidity conditions, and satisfactory performance can be obtained only when the toner is combined with a specific carrier.

For such specific carrier particles, resin-coated carrier particles having a magnetic material surface coated with a resin are suitable.

Generally, under the conditions of high temperature and high humidity, the toner easily films on the carrier particles, the surface of the photoconductor and the cleaning blade, but by using the toner, filming on the surface of the photoconductor and the cleaning blade is suppressed. However, in the collision of high impact carrier particles and toner, if unevenness exists on the surface of the carrier particles, a part of the toner will film on the carrier particles. Such a phenomenon is remarkable in a carrier having a surface with many irregularities such as iron powder. In order to solve such a phenomenon, by coating the surface of the magnetic material with a resin to make it hydrophobic and smooth, the filming of the toner is suppressed under high temperature and high humidity conditions, and the triboelectric charging property is stabilized, and The durability is improved and a good image can be obtained for a long time.

As the resin contained in the toner constituting the developer of the present invention, a resin obtained by reacting a carboxy group present in the polymer component with a polyvalent metal compound 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 in the molecular weight distribution curve measured by gel permeation chromatography (GPC), The maximum value on the low molecular weight polymer component side is 1 × 10 ³ ~
It preferably has at least two local maxima of 2 × 10 ⁴ and 1 × 10 ⁵ to 2 × 10 ⁶ on the high molecular weight side. By designing like this, it becomes possible to fix at a lower temperature,
Further, since the elastic modulus at the time of melting can be increased, the offset resistance can be further improved. At the same time, blocking resistance can be improved together. Furthermore, the resin can be made tougher by the high molecular weight polymer component, and the generation of fine powder due to the collision with the carrier or the photoreceptor can be suppressed,
Contamination of the carrier and the surface of the photoconductor can be prevented.

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.
The fine particles generated from the toner component due to the collision of the carrier particles with the surface of the photoconductor are mainly due to the relatively fragile component having a low molecular weight.Thus, such a low molecular weight polymer component is crosslinked by at least a metal ion bond to obtain a toughness. By this, generation of fine powder, which is a factor of filming, can be suppressed.

As the monomer for obtaining the polymer of the main resin of the toner, at least one selected from styrene-based monomers, acrylic acid such as methacrylic acid, and ester-based monomers 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. A preferred monomer having a carboxy group to be copolymerized is a half-ester compound having a structure obtained by an esterification reaction of a hydroxyl group-containing acrylic acid ester, methacrylic acid ester or a derivative thereof and a dicarboxylic acid compound.

When a carboxy group is introduced at a position that has little influence on the main chain structure as described above, the steric hindrance of the chemical structure becomes small and the reaction with the polyvalent metal compound proceeds efficiently, thereby achieving the object of the present invention. It is possible to generate an effective ionic bond to obtain a good crosslinked structure.

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, pn
-Nonylstyrene, pn-decylstyrene, pn-
Dodecyl styrene, p-methoxy styrene, p-phenyl styrene, p-chloro styrene, 3,4-dichloro styrene, etc. 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 carboxyl 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 is added. It may be a hydroxyalkyl ester obtained by esterifying a divalent alcohol such as propylene glycol.

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

However, in the above general formula, 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).

However, 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.

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

However, in the formula, R ₆ represents H or CH ₃ , j represents an integer of 3 to 6, and k represents an integer of 0 to 8.

However, in the formula, R ₇ is H or CH ₃ , l is an integer of 3 to 6, and Y is
Represents 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, M
g, Ca, Sr, Ba) and zinc group elements (Zn, Cd) are preferred,
Particularly, Mg and Zn are 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 ester-based monomer and the half ester compound, the amount is 0.1 to 1 mol per 1 mol of the half ester compound charged. It 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 with the polyvalent metal compound, the carboxy machine and the metal atom contained in the polymer component are ionic bond, a kind of cross-linked structure by this ionic bond Is appearing. This ionic bond is much slower than covalent bonds.

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 decrease. 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, either a high molecular weight polymer component or a low molecular weight polymer component by polymerization. The first-stage polymerization in which one of the polymer components is first produced is carried out, and then the produced one polymer component is dissolved in a monomer which gives a polymer constituting the other polymer component. By carrying out the second-stage polymerization, the other polymer component is produced, and as a result, a polymer having a bimodal molecular weight distribution can be obtained. Thus, the polymer obtained by the two-stage polymerization is presumed to be a mixture of a low molecular weight polymer component and a 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 Blue 3), 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 exhibit ferromagnetism, 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 a volume average particle diameter 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 fluid or solid paraffin wax, polyamide wax, polyhydric alcohol ester, silicone varnish. , Aliphatic fluorocarbon and the like can be used.
A wax having a softening point (ring and 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 volume average particle diameter of 5 mμ to 2 μ, and preferably 5 mμ to
A particle that is 500 mμ. The specific surface area by BET method is 2
It is preferably 0 to 500 m ² / g. The mixing ratio with the toner is 0.01 to 5 wt%, preferably 0.01 to 2.0 wt%. Examples of such inorganic fine powder 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 and the like, but silica fine powder is particularly preferable.

The silica fine powder referred to 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, it is not possible to obtain a toner having a desired particle diameter by spraying or kneading a melt-kneaded product in an extruder in a molten state with a spray dryer or the like in a molten state.

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 particularly 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 seconds.

The resin-coated carrier coated with the resin in the developer of the present invention has a spherical and smooth surface state because the resin coating is applied.

For this reason, it is considered that the toner is effectively triboelectrically charged, carrier scattering and toner scattering can be prevented, fogging and carrier adhesion are prevented, and a clear image can be obtained. In addition, by using the resin-coated carrier described above, even if a large number of copies are performed under high temperature and high humidity conditions, the toner does not physically adhere strongly to the toner even if it has good releasability and is subjected to strong pressure. It is considered that the filming on the carrier does not occur, and as a result, a clear image having good durability without fogging, toner scattering, carrier adhesion and the like can be obtained.

In particular, the following copolymer used for resin coating of the carrier is
It can be obtained by polymerizing styrene monomer as a hard component and acrylic acid (or methacrylic acid) or its ester, which has a tough and flexible function. At the same time, the drawback can be solved. 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.

The resin used for coating the carrier particles is obtained by polymerizing a styrene-based monomer and a monomer component containing acrylic acid or its ester monomer and / or methacrylic acid or its ester monomer. It is a resin containing a copolymer.

Examples of the styrene-based monomer include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene,
α-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonyl Examples thereof include styrene, pn-decylstyrene, pn-dodecylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, and 3,4-dichlorostyrene. Among them, styrene is Most preferred.

Examples of the acrylic acid ester and methacrylic acid ester copolymerized with the styrene-based monomer include methyl acrylate, ethyl acrylate, n-propyl acrylate, iso-propyl acrylate, n-butyl acrylate, iso-butyl acrylate, tert-butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, n-octyl acrylate, iso
-Octyl acrylate, n-dodecyl acrylate,
Acrylic esters such as 2-hydroxyethyl acrylate, 2-methoxyethyl acrylate, 2-chloroethyl acrylate, benzyl acrylate, n-methylaminoethyl acrylate and dimethylaminoethyl acrylate, and methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, iso-propyl methacrylate, n-butyl methacrylate, iso-butyl tacrylate, tert-butyl methacrylate, 2-
Ethylhexyl methacrylate, cyclohexyl methacrylate, n-octyl methacrylate, iso-octyl methacrylate, n-dodecyl methacrylate, 2-
Hydroxymethacrylate, benzylmethacrylate,
Methacrylic acid esters such as n-methylaminoethylmethacrylate and dimethylaminoethylmethacrylate may be mentioned, of which methylmethacrylate is most preferred.

The above-mentioned copolymer is a commonly used emulsion polymerization, bulk polymerization,
It can be produced by suspension polymerization or solution polymerization.

The molecular weight of the copolymer is the weight average molecular weight (Mw)
Is 10,000 or more, number average molecular weight (Mn) is 2000 or more, Mw / Mn is
When it is 2.0 or more, the weight average molecular weight is less than 10,000, the number average molecular weight is less than 2000, and Mw / Mn is less than 2.0, the coating resin is easily peeled off due to brittleness and the durability tends to be poor.

Further, the glass transition temperature (Tg) of the copolymer is preferably 60 ° C. or higher. When the temperature is lower than 60 ° C, the toner has tackiness, and the toner is apt to adhere to the film to easily cause filming.

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

Resin of the resin-coated carrier used in the present invention,
Styrene monomer (St) and acrylic ester (AE)
And / or a copolymer having a methacrylic acid ester (MAE) as a constituent component is preferable. The styrene component has the effect of making the resin hard and efficiently frictionally charged, and the acrylic ester and methacrylic ester components have the effect of making the resin tough. Due to the synergistic effect of both, it becomes a hard and tough resin and durable. It can be a carrier with good properties.

For this reason, the weight composition ratio of the copolymer is St / AE and / or M
AE = 9/1 to 1/9 is preferable. As another effect, the charge amount can be easily adjusted arbitrarily by changing the component ratio.

The magnetic material of the resin-coated carrier in the present invention is a substance that is 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 alloys containing these metals. Or a compound, an alloy containing no ferromagnetic element but exhibiting ferromagnetism by appropriate heat treatment, for example, an alloy of the type called Heusler alloy such as manganese-copper-aluminum or manganese-copper-tin, or chromium dioxide. Etc. can be used.

Ferrite is a generic name 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. Also, because ferrite is an oxide, its specific gravity is smaller and lighter than metal powder such as iron powder and nickel powder, so mixing and stirring with toner is easy, and uniform toner concentration and charge amount are realized. It is suitable for this. Moreover, ferrite has a higher electric resistance than iron powder, nickel powder, cobalt powder, etc. (10 ⁸
~ 10 ¹² Ωcm), and even if the resin insulation layer on the surface is a thin film of about 0.5 μm, it has the advantage of being able to realize 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 .

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 Ωcm, and a specific gravity of 4.0.
˜5.5, and the porosity is preferably 1.0 to 10%.

The method for producing a resin-coated carrier used in the present invention is to prepare a coating solution by dissolving a coating resin and other resin components added as necessary in an organic solvent to prepare a coating layer on the carrier surface by, for example, 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 200 μm or less, particularly 5 μm or more and 100 μm or less, in order to improve resolution and gradation reproducibility. Here, the carrier particle size is 100 μm, especially 2
If it exceeds 00 μm, 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.

Further, in order to prevent the charge from being injected by the bias voltage to attach the carrier to the surface of the photoconductor or to eliminate the charge forming the latent image, the resistance of the carrier is 10 ⁸ Ωcm or more, preferably 10 ¹³ Ω or more. , More preferably 10 ¹⁴ Ωcm
It is better to have insulation.

In the present invention, the particle diameter of the toner and carrier, or the average particle diameter means the volume average particle diameter, and the volume average particle diameter of the toner is a value measured by a Coulter counter (manufactured by Coulter Co.), The volume average particle diameter of carrier particles is a value obtained by actually measuring the particle diameter of each particle with a microscope.

The specific resistivity (resistivity) of the particles, after tapping putting particles in a container having a sectional area of 0.50 cm ^2, 1 mm about the thickness by applying a load of 1 kg / cm ² on packed particles And an electric field of 10 ² to 10 V ⁵ / cm is generated between the weight and the bottom electrode, and the electric current value flowing at that time is obtained.

The mixing ratio of the above-mentioned toner and carrier is 1 to 40 wt% of the toner concentration (the weight ratio of the toner in the developer), preferably 1.
It is suitable to set to 5 to 25 wt%.

In this specification, the softening point is a descending flow tester "CF
Using T-500 "(manufactured by Shimadzu Corporation), load the measurement conditions
20kg / cm ² , nozzle diameter 1mm, nozzle flow 1mm, preheating at 80 ℃ for 10 minutes, heating rate 6 ℃ / minute, sample amount 1c
When measured and recorded as m ³ (weight expressed as true specific gravity × 1 cm ³ ), when the height of the S-shaped curve in the flow rate tester's blanker drop-temperature curve (softening flow curve) is h / 2, h / 2 Refers to the temperature at.

The glass transition point is the differential scanning calorimeter "constant temperature DSC".
(Ideal Denki Co., Ltd.), when measured at a heating rate of 10 ° C / min, an extension line of the baseline below the glass transition point of the DSC thermogram in the glass transition region and the peak portion from the rising portion of the peak Is the value when the temperature at the intersection with the tangent line showing the maximum slope between is defined as the glass transition point.

The values of the number average molecular weight Mn and the weight average molecular weight Mw in the polymer can be measured by various methods, and there is some variation depending on the measuring method.

In the present specification, Mn and Mw are defined as values obtained by the following measuring method.

That is, depending on the gel permeation chromatography (GPC), the weight average molecular weight Mw is
And the number average molecular weight Mn are measured. At a temperature of 40 ° C., a solvent (tetrahydrofuran) is flowed at a flow rate of 1.2 ml / min,
Inject 3 mg of a tetrahydrofuran sample solution with a concentration of 0.2 g / 20 ml as the sample weight and perform the measurement. In the measurement of the molecular weight of the sample, the measurement conditions are selected such that the sample has a molecular weight within a range in which the logarithm of the molecular weight and the count number of the calibration curve made by several kinds of monodisperse polystyrene standard samples are linear.

In addition, the reliability of the measurement result, NB performed under the above measurement conditions
It can be confirmed that the S706 polystyrene standard sample has a weight average molecular weight Mw of 28.8 × 10 ^{4 and a} number average molecular weight Mn of 13.7 × 10 ⁴ .

Any GPC column may be used as long as it satisfies the above conditions.
Specifically, for example, TSK-GEL, GMH ₆ (manufactured by Toyo Soda Co., Ltd.) and the like can be used.

〔Example〕

 Next, specific examples of the present invention will be described.

(Synthesis of Resin) Synthesis Example-1 A separable flask having a capacity of 3 and equipped with a thermometer, a stirrer, a nitrogen gas introducing tube, and a flow-down condenser has 500 m of toluene.
After adding l, nitrogen gas was introduced from the gas introduction tube to make the inside an inert atmosphere, and then heated in an oil bath to the reflux temperature of toluene. Then, a solution consisting of 210 g of styrene, 60 g of n-butyl acrylate, 30 g of methyl methacrylate and 0.9 g of benzoyl peroxide was placed in the flask and reacted at reflux temperature for 14 hours to obtain a high molecular weight polymer.

Then, a polymerization reaction was carried out while dropping a solution of 487 g of styrene, 35 g of α-methylstyrene, 105 g of n-butyl acrylate, 73 kg of monoacryloyloxyethyl succinate, and 42 g of benzoylperoxide in a flask having the high molecular weight polymer solution. I went. After the solution was added dropwise, a polymerization reaction was performed for 4 hours to obtain a low molecular weight polymer.

Next, 8 g of zinc oxide was added into a flask having a solution containing the high molecular weight polymer and the low molecular weight polymer, and the reaction was carried out for 2 hours while stirring at the reflux temperature.

After completion of the reaction, the toluene solvent was distilled off under reduced pressure, and the carboxy group and the metal compound were reacted to obtain Resin A of the present invention.

The molecular weight distribution of this resin A was measured by gel permeation chromatography (HLC-802UR.GMH ₆ column, manufactured by Toyo Soda Co., Ltd.), and the maximum values were 7.5 × 10 ³ and 2.8 × 10 ⁵ . It was a bimodal distribution. The weight average molecular weight (Mw) was 120,000 Mw / Mn was 17.1.

Synthesis Example-2 180 g of styrene as a high molecular weight polymer component, 30 g of n-butyl acrylate, 60 g of n-butyl methacrylate, 30 g of methyl methacrylate, 1.5 g of azobisisobutyronitrile
As a low molecular weight polymer composition, 372 g of styrene, 70 g of α-methylstyrene, 70 g of n-butyl acrylate, 70 g of n-butyl methacrylate, 70 g of methyl methacrylate, 48 g of monoacryloyloxyethyl isophthalate and 22.4 g of zinc acetate as a metal compound. Other than used, Synthesis Example-1
Resin B was obtained in the same manner.

This resin B had the maximum values of the molecular weight distribution at 1.2 × 10 ⁴ and 2.4 × 10 ⁵ , and had Mw 115,000 and Mw / Mn = 9.5.

Synthesis Example-3 150 g of styrene as a high molecular weight polymer component, 50 g of 2-ethylhexyl acrylate, 0.4 of benzoyl peroxide
g, 52 g of styrene as a low molecular weight polymer component, 40 g of α-methylstyrene, and 120 g of 2-ethylhexyl acrylate.
80 g of monoacryloyloxypropyl succinate,
Resin C was obtained in the same manner as in Synthesis Example-1 except that 40 g of benzoyl peroxide and 13 g of magnesium oxide were used as the metal compound.

The maximum value in the molecular weight distribution of Resin-C is 9.2 × 10 ³ and 3.9
× 10 ⁵ , and the weight average molecular weight (Mw) is 102,000, Mw
/ Mn was 12.5.

Synthesis Example-4 195 g of styrene as a high molecular weight polymer component, 175 g of n-butyl methacrylate, 40 g of methyl methacrylate and 2.0 g of benzoyl peroxide, and 215 g of styrene as a low molecular weight polymer component, 70 g of α-methylstyrene, 210 g of n-butyl methacrylate. Resin D was obtained in the same manner as in Synthesis Example-1, except that 70 g of methyl methacrylate, 40 g of monoacryloyloxypropyl isophthalate, 36 g of benzoyl peroxide were used as the metal compound, and 20 g of zinc acetate was used. The maximum molecular weight in the molecular weight distribution of Resin D is 3.8.
The values were × 10 ³ and 1.8 × 10 ⁵ . Mw96,000 and Mw / Mn are 13.7
Met.

Synthesis Example-5 130 g of styrene as a high molecular weight polymer component, 50 g of 2-ethylhexyl acrylate, 20 g of methyl methacrylate, 0.4 g of benzoyl peroxide, 520 g of styrene as a low molecular weight polymer component, 40 g of α-methylstyrene, 120 g of 2-ethylhexyl acrylate. , Methyl methacrylate 80
g, monoacryloyloxyethyl succinate 40 g, benzoyl peroxide 40 g, and zinc oxide 4.0 g as the metal compound were used in the same manner as in Synthesis Example-1 except that Resin E was used.
Got The maximum values of the molecular weight in the resin-E molecular weight distribution are 8.5 × 10 ³ and 4.6 × 10 ⁵ , and Mw is 134,000, Mw / Mn
Was 16.3.

Synthesis Example-6 180 g of styrene as a high molecular weight polymer component, 60 g of n-butyl acrylate, 30 g of methyl methacrylate, 0.9 g of benzoyl peroxide, 30 g of monoacryloyloxyethyl succinate, and 4 g of styrene as a low molecular weight polymer component.
87g, α-methylstyrene 35g, n-butyl acrylate
105 g, monoacryloyloxyethyl succinate 73
Resin F was obtained in the same manner as in Synthesis Example-1 except that 7.3 g of zinc oxide was used as the metal compound of g, 35 g of benzoyl peroxide.

The maximum values of the molecular weight of Resin-F were 6.4 × 10 ³ and 3.3 × 10 ⁵ , and Mw was 126,000 and Mn was 20.1.

(Synthesis of Comparative Resin) Comparative Synthesis Example-1 Synthesis Example-1 except that 8 g of zinc oxide was deleted from Synthesis Example-1.
Resin G was obtained in the same manner as in 1.

The maximum values of Resin G are 7.1 × 10 ³ and 2.8 × 10 ⁵ , and Mw is 118,
000 and Mw / Mn were 18.1.

Comparative Synthesis Example-2 After putting 400 g of toluene in a two-separable flask and replacing the air with nitrogen gas, 750 g of styrene, 200 g of -n-butyl acrylate, and amber are added while heating this system to the boiling point of toluene and stirring. Solution polymerization was carried out by dropwise adding a mixture of 50 g of acid monoacryloyloxyethyl ester and 10 g of benzoyl peroxide as a polymerization initiator 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 the system was gradually raised to 180 ° C. and the toluene was removed under reduced pressure to remove styrene-acrylic acid-n.
A resin H which is a reaction polymer of a -butyl-succinic acid monoacryloyloxyethyl ester copolymer and zinc oxide was obtained.

Comparative synthesis example-3 Xylene 90g, put in a separable flask, further,
Styrene 75 g, butyl acrylate 20 g, monobutyl maleate 5 g, divinylbenzene 0.5 g were added, the gas phase was replaced with nitrogen gas and then kept at 80 ° C., and xylene 10 g dissolved with benzoyl peroxide 1.2 g was added, 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. Resin I obtained here had an Mw / Mn of 27 and an Mw of 233,000.

(Preparation of Toner) 100 parts by weight of each of Resins A to F obtained in Synthesis Examples 1 to 6 above, 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-E
2 parts by weight (manufactured by Hoechst Co.) were mixed in a Henschel mixer, then sufficiently kneaded by a two-roll mill at a temperature of 130 ° C., then allowed to cool, coarsely crushed, and then crushed by a jet mill, By classification, toners 1 to 6 according to the present invention having a volume average particle diameter of 11.0 μm were obtained.

(Preparation of Comparative Toner) Comparative Toner (1) Comparative Toner (1) was prepared in the same manner as Toner 1 except that a mixture of 100 parts by weight of Resin G and 10 parts by weight of carbon black (“Mogal L”, manufactured by Cabot Corporation) was used. ) Got.

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

Comparative Toner (3) Resin I 100 parts by weight, di-t-butylsalicylic acid zinc salt 5 parts by weight, carbon black 8 parts by weight, metal salt dye (trade name: Sapon First Black B, CIAcod Black, BA
4 parts by weight (manufactured by SF company) 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 and used as a comparative toner (3).

(Production 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 volume average particle size of the carrier a was 100 μ, the magnetization was 28 emu / g, and the specific resistance was 10 ¹⁴ Ωcm 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 (Mw73,000, A carrier having an average film thickness of 0.8 μm of the coating layer was produced in the same manner as the carrier a except that Mn: 24,000, Tg: 98 ° C.) was used. This is referred to as "carrier b". The volume average particle diameter of this carrier was 100 μ, and the magnetization 30 emu / g specific resistance was 10 ¹⁴ Ωcm 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. Volume average particle size is
The magnetization was 100 μm and the magnetization was 26 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): EFV250 / 400 (manufactured by Nippon Iron Powder Co., Ltd.), which is iron powder particles, was used as a comparative carrier b.

(Preparation of Developer) Example-1 49.75 parts by weight of Toner 1 and hydrophobic silica (Aerosil R-9)
72, manufactured by Aerosil Co., Ltd.), and then mixed with 950 parts by weight of the carrier a to obtain the developer-1 of the present invention.
Got

An electrophotographic copying machine "U-Bix500" using the above developer-1.
0 "(made by Konishi Rokusha Kogyo Co., Ltd.) is used to form and develop an electrostatic image, the obtained toner image is transferred onto a transfer paper, and then fixed by a heating roller fixing device to form a copy image. The minimum fixing temperature (minimum temperature of a heat roller capable of fixing) and the offset generation temperature (minimum temperature at which an offset phenomenon occurs) were measured by the following methods.

Minimum fixing temperature: After creating an unfixed image with the above copying machine, the surface layer is a heat roller with a diameter of 50φ and the surface layer is made of Teflon (polytetrafluoroethylene manufactured by DuPont), and the surface layer is silicone rubber "KE-1300RTV". A toner image formed by the sample toner transferred onto a transfer paper of 64 g / m ² by a fixing device consisting of a pressure roller formed by Shin-Etsu Chemical Co., Ltd. has a linear velocity of 200 mm /
The fixing image formed by repeating the operation of fixing at a linear pressure of 0.8 kg / cm and a nip width of 8 mm for 5 seconds in increments of 5 ° C within the range of 100 to 240 ° C. Kimwipe rubbing was performed on the above, and sufficient rubbing resistance was defined as the minimum fixing temperature with the lowest set temperature for the fixed image. The fixing solution used here does not have a silicone oil supply mechanism.

Offset occurrence temperature: The offset occurrence temperature is measured according to the minimum fixing temperature, or 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. 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 is repeated with the set temperature of the heat roller of the fixing device being sequentially increased. The lowest set temperature at which the stain was generated 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 under environmental conditions of a temperature of 55 ° C. and a relative humidity of 60% for 1 day to examine whether or not aggregates were formed.

Next, using the above-mentioned developer, a copying test was performed on 100,000 sheets under the environmental conditions of normal temperature and normal humidity (20 ° C, 60% RH) and high temperature and high humidity (30 ° C, 80% RH). I did.

Image quality: The sharpness of the copied image was examined at the beginning and end of the 100,000 times development process.

Filming resistance: For filming resistance, the surface of the carrier of the carrier and the cleaning plate at the beginning and end of the 100,000 times development process are observed with an electron microscope or visually to check for the presence of deposits. It was

The results are as shown in Table 1. In the table, "good" for image quality means that the image is clear, and "bad"
Indicates that there is a lot of fog and it is unclear.

Fog: It was shown by the relative density of a white background portion with a document density of 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 Cleaning property: The cleaning property was determined by observing the surface of the photosensitive member after cleaning the surface of the photosensitive member with a cleaning member and determining the presence or absence of an adhered substance.

The results are shown in Table 1.

Examples 2 to 6 Toners 2 to 6 and hydrophobic silica are mixed in the same manner as in Example 1 and then mixed with a carrier to obtain developers-2 to 6, and the test is performed in the same manner as in Example 1. It was The result is the first
Shown in the table.

Comparative Example-1 5 parts by weight of the comparative toner (1) and 95 parts by weight of the comparative carrier (a) were mixed to obtain a comparative developer- (1).

This comparative developer (1) was used and tested in the same manner as in Example-1. The results are also shown in Table 1.

Comparative Example-2 Comparative developer-2 was prepared by mixing 4 parts by weight of the comparative toner (2) and 96 parts by weight of the comparative carrier (b) of iron powder, and tested in the same manner as in Example-1. .

The results are also shown in Table 1.

Comparative Example-3 Comparative toner- (3) was prepared by mixing 10 parts by weight of comparative toner (3) and 90 parts by weight of comparative carrier (b), and the same test as in Example-1 was conducted. The results are also shown in Table 1.

As shown in Table 1, in the developers 1 to 6 of the present invention,
It has excellent low-temperature fixability, offset resistance, and blocking resistance, has a wide fixable range, and does not cause fogging under environmental conditions of normal temperature and normal humidity and high temperature and humidity, and has good cleaning properties. It is excellent in triboelectrification without fusion with the cleaning blade on the surface of the photoconductor, stable in long-term tube and excellent in durability and temperature and humidity resistance.

On the other hand, in Comparative Developer- (1), the low-temperature fixability is poor, and due to the brittle low-molecular weight component, the durability is poor due to the contamination of carriers and the like. And the durability was inferior. Further, the comparative developer- (2) is inferior not only in low-temperature fixability but also in durability. Especially under high temperature and high humidity conditions, filming or the like causes destabilization of triboelectrification and cleaning. It was inferior in durability and temperature / humidity resistance, in which defects were generated and only an unclear image was obtained.

In Comparative Developer- (3), low-temperature fixability and anti-offset property were poor, and further, it seems that the crosslinking reaction by the metal did not proceed well, and the filming property was poor and the durability was poor. In particular, under high temperature and high humidity conditions, an unclear image is formed due to destabilization of triboelectrification, such as occurrence of filming and cleaning failure, resulting in poor durability and resistance to temperature and humidity.

〔The invention's effect〕

Copying by electrophotography has become a large number of sheets and is automated and unmanned. Therefore, there is a strong demand for speeding up, guarantee of copy image quality, and reliability, and the present invention has made a further advance in responding to this.

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

Claims (2)

[Claims] 1. Toner particles (A) whose main component is a resin obtained by reacting a polyvalent metal compound with a carboxy group present in a polymer component, and a resin-coated carrier having ferrite particle surfaces coated with a resin. In an electrostatic latent image developer containing particles (B), the main component of the toner particles 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 in the molecular weight distribution, 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 polymer obtained from (a) a styrene-based monomer, (b) an acrylic ester-based monomer, and (c) a monomer represented by the following general formula (A) is reacted with a polyvalent metal compound. And a resin-coated carrier Resin of the child (B) is polymerized composition ratio of styrene monomer to the acrylic acid ester monomer is 9:
1 to 1: 9, the polymerization composition ratio of styrene monomer to methacrylic acid ester monomer is 9: 1 to 1: 9, or styrene monomer to acrylic acid ester monomer and methacrylic acid ester An electrostatic latent image developer, which is a copolymer in which the polymerization composition ratio of the system monomers is 9: 1 to 1: 9. General formula (A) (In the formula, R ₁ is H or CH ₃ , and L is a divalent linking group having 3 or more carbon atoms and having an ester bond in the molecular chain, and may have a substituent.) 2. The electrostatic latent image developer according to claim 1, wherein the polyvalent metal compound is a zinc group metal compound or an alkaline earth metal compound.