JPH0776842B2 - Electrostatic latent image developer using ionic cross-linking resin and silicone resin - Google Patents

Description

The present invention relates to a developer for developing an electrostatic latent image in electrophotography, electrostatic recording, electrostatic printing and the like.

[Background of the Invention]

In electrophotography, a uniform surface charge is applied to a photosensitive member composed of a photoconductive element in a dark place, and then exposed to form an electrostatic latent image, and then the electrostatic latent image is developed. A visible image is formed.

Generally, the method of developing such an electrostatic latent image (hereinafter abbreviated as a latent image) is roughly classified into a wet developing method and a dry developing method.
The wet development method is a method of developing using a liquid developer formed by dispersing various pigments and dyes as fine particles in an insulating organic liquid, and the dry development method is a method of developing with a natural or synthetic resin such as carbon black. This is a method of developing using a fine powder test powder called a toner containing a colorant dispersed therein.
In this dry development method, a so-called bristle brush method, an impression method, and a powder cloud method, which use a developer containing only toner as a main component, and a mixture of toner and a carrier made of iron powder or glass beads are used as a developer. There are so-called magnetic brush method and cascade method which are used by

By these developing methods, charged toner particles in the developer adhere to the latent image to form a visible image. This visible image is transferred as it is onto the photoconductor or to another image support such as paper by heat, pressure, solvent vapor or the like, and then fixed.

[Problems to be solved by the invention]

In general, the carrier that constitutes the developer is roughly classified into a conductive carrier and an insulating carrier.

As the conductive carrier, oxidized or non-oxidized iron powder is usually used, but in the developer using this iron powder carrier, the triboelectric chargeability against the toner is unstable, and the obtained visible image is There is a drawback that fogging occurs. That is, the toner substance is liable to adhere to the surface of the iron powder carrier particles during friction with the toner, which increases the electric resistance of the carrier particles and reduces the bias current normally applied during development. The image becomes unstable, and as a result, the image density of the visible image is reduced and the fog is increased. Therefore, if images are continuously formed in an electrophotographic apparatus using a developer that uses an iron powder carrier, the developer deteriorates in a few fractions, and it is necessary to replace the developer as soon as possible, so that good images continue to be produced. I can't get it.

The insulating carrier is typically a carrier obtained by uniformly coating the surface of a carrier core material made of a ferromagnetic material such as iron, nickel and ferrite with an insulating resin. In the developer using the insulating carrier, the toner substance is less likely to be fused to the surface of the carrier particles as compared with the case of the conductive carrier.

However, even a developer composed of this insulating carrier and toner may not be able to obtain stable triboelectric chargeability. That is, the developer composed of the toner and the carrier is, in the developing device, a carrier particle, a toner particle, a carrier particle and a toner particle, a carrier particle and / or a toner particle and a stirring member, a container wall, or the like. However, if the coating layer of the carrier is liable to wear due to friction, the stability of the carrier's triboelectrification property will be lost, and the toner particles will easily break due to mechanical shock or pressure. If the toner is fine, the fine powder causes fogging, and if the toner particles are easily abraded by friction, the toner substance easily adheres to the surface of the coating layer of the carrier and the carrier is Triboelectrification becomes unstable.

On the other hand, a carrier in which the surface of a carrier core material is coated with a thermoplastic resin or a cross-linking resin has been developed. However, in this technology, since only the characteristics of the carrier are a problem, the drawback of the toner used in combination is Therefore, stable triboelectrification cannot be obtained, and eventually there is a problem that a good image without fog cannot be formed many times.

In addition, 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 the temperature at which it can be fixed after the fixing device is activated. (D) Lower the temperature of the heat roller by absorbing heat to the transfer paper. In order to reduce the size of the heating roller to enable continuous copying over a large number of times, and (e) to improve thermal safety, the power consumption of the fixing heater is reduced to lower the temperature of the heat roller. 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, a part of the toner forming the image is transferred to the surface of the heat roller during the offset development, that is, the fixing, and this is transferred again to the transfer paper which is sent next to form the image. Since the development of stains is likely to occur, it is necessary to provide the toner with the performance of preventing the occurrence of offset development, that is, the anti-offset property.
Various studies have been made in the past to obtain the above-mentioned performances, but satisfactory performances have not yet been obtained.

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 carboxy 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 surface of the photoconductor, and cleaning failure occurs due to fusion adhesion to the cleaning blade, and as a result, good images cannot be obtained continuously and durability deteriorates.

[Object of the Invention]

An object of the present invention is to provide a developer which can be preferably used in a heat roller fixing method having good low-temperature fixability, offset resistance and blocking resistance.

Another object of the present invention is to provide a developer having excellent durability, which is capable of stably forming a good image having stable triboelectricity and no fog a number of times.

Further, the object of the present invention is excellent in durability that a stable image can be obtained even when used many times without causing filming on carrier particles, a surface of a photosensitive member, a cleaning blade, etc. even under high temperature and high humidity environmental conditions. To provide a developer.

[Structure of Invention]

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

According to the developer having such a constitution, since the toner is ionically bonded by the metal to form a crosslinked structure, the toner is more easily melted by heating than the resin crosslinked by the covalent bond and the fixability at low humidity is improved. At the same time, by virtue of having a crosslinked structure, the toner made of this resin is tough and has excellent triboelectric chargeability, and there is no generation of fine powder which causes toner particles to break due to mechanical impact, and Even when the carrier particles, the stirring member, the vessel wall, the sleeve surface, and the like are rubbed, the resin material in the toner is less likely to be scraped off.

On the other hand, in the carrier particles, since the surface energy of the carrier particle surface is small because it is coated with the silicone resin, the surface of the carrier particle is highly slippery, and other substances do not easily adhere to the surface of the carrier particle such as resin in the toner. Transfer, that is, toner spent is less likely to occur, and the triboelectric chargeability of the carrier becomes stable for a long period of time. Moreover, since the carrier particles are coated with the hydrophobic and low surface energy silicone resin, they have stable triboelectrification properties and durability even under high temperature and high humidity conditions under normal temperature and normal humidity conditions.

Further, since the binder of the toner contains a specific resin as a main component, the offset resistance is excellent, and the molten toner does not transfer to the fixing roller when fixing the toner on the heat roller, and therefore the fixing roller is not stained and the image is stained. Is unlikely to occur. Further, there is no so-called toner filming in which the resin in the toner adheres to the surface of the photoconductor to form a film, and therefore the photoconductor can be used stably for a long period of time. As a result, it is possible to form a clear image free from fog a number of times stably and at high speed.

Hereinafter, the present invention will be described in detail.

In the present invention, the silicone resin used for coating the carrier particles is not particularly limited, but for example, a condensation reaction type silicone resin that cures by the reactions shown below and can be particularly preferably used.

Heat dehydration condensation reaction Room temperature moisture curing reaction In the formula, OX represents an alkoxy group, a ketoxime group, an acetoxy group, an aminoxy group or the like.

A particularly preferred substituent in the condensation reaction type silicone resin is a methyl group. In the coating layer obtained by the condensation reaction type silicone resin having a methyl group as a substituent, the structure becomes dense, the water repellency is considerably good, and the carrier having good moisture resistance can be obtained.

As the condensation reaction type silicone resin, either a heat setting type silicone resin or a room temperature setting type silicone resin can be used. When using a heat-curable silicone resin, it is necessary to heat at about 200 to 250 ° C,
When the room temperature curable silicone resin is used, it is not necessary to heat it to a particularly high temperature for curing, but it may be heated within the range of 150 to 220 ° C. to accelerate the curing.

Room temperature curing type silicone resin can be used under normal atmosphere.
It is a silicone resin that cures at a temperature of about 20 to 25 ° C or slightly higher, and does not require a temperature higher than 100 ° C for curing.

Examples of commercially available condensation reaction type silicone resins include the following.

Torre Silicone: "SR-2400", "SR-240"
6 "," SR-2410 "," SR-2411 "Shin-Etsu Chemical Co., Ltd .:" KR-152 "," KR-271 "," KR-25 "
1 "," KR-220 "," KR-255 "In forming the coating layer, a silicone resin may be used alone or in combination, or a silicone resin mixed with another resin may be used. Good. Examples of such other resins include acrylic resin, styrene resin, epoxy resin, urethane resin, polyamide resin, polyester resin, acetal resin, polycarbonate resin, phenol resin, vinyl chloride resin, vinyl acetate resin, cellulose resin, polyolefin resin. Examples thereof include copolymer resins, compounded resins and the like.

Also, the value of the weight ratio Si / C of silicon and carbon in the silicone resin is
It is preferably 1.7 to 2.2, and when this value is too large, the chargeability is easily affected by temperature change, and the coating layer becomes brittle, while when this value is too small, the coating layer becomes soft.

Further, the silicone resin may contain silicone oil in order to improve moisture resistance and releasability.

As the carrier core material, for example, magnetic metals such as iron, copper, nickel and cobalt, magnetic oxides such as ferrite and magnetite, copper, carbon random, glass beads and others can be used. When the carrier core material is a magnetic material, a carrier that gives a developer suitable for the magnetic brush development method can be obtained. As such a carrier core material, one having a volume average particle diameter of 1 to 1000 μm is usually used, but one having a volume average particle diameter of 5 to 200 μm is particularly preferable.

The carrier constituting the developer of the present invention is, for example, a coating liquid obtained by dissolving a silicone resin in a solvent is applied to the surface of a carrier core material, and then usually heated and dried to volatilize and remove the solvent, and then dried. It can be produced by curing the coating layer at some time or after drying.

Specific coating methods using the coating liquid include a dipping method in which powder of the carrier core material is immersed in the coating liquid, a spray method in which the coating liquid is sprayed on the carrier core material, and the carrier core material is floated by flowing air The fluidized bed method of spraying the coating liquid on the carrier core material in the state, the method of rolling treatment of the carrier core material on the surface where the coating liquid is present, etc. can be mentioned, especially when the fluidized bed method is used. Can form a uniform coating film on the surface of the carrier core material, and can stably form the coating layer. The coating method by the fluidized bed method is described in, for example, JP-A-54-155049.

Other additives may be added to the coating liquid for forming the coating layer, if necessary. The solvent is not particularly limited as long as it dissolves the silicone resin, and examples thereof include aromatic hydrocarbons such as toluene and xylene; ketones such as acetone and methyl ethyl ketone; tetrahydrofuran, dioxane, higher alcohols or mixed solvents thereof. Can be used.

The temperature for curing the coating layer is, for example, about 150 to 280 ° C. When using room temperature curable silicone resin,
Although heating is not particularly required for curing, it may be heated to, for example, about 150 to 220 ° C. in order to increase the mechanical strength of the coating layer. When drying, lead, iron, such as octylic acid and naphthylic acid,
Metal soaps such as cobalt, manganese, and zinc may be used as the drying accelerator, and organic amines such as ethanolamine can be effectively used as the drying accelerator.

The thickness of the coating layer thus obtained is usually 10 μm or less, preferably 0.2 to 5 μm.

The volume average particle size of the carrier constituting the developer of the present invention is, for example, 1 to 1000 μm, preferably 5 to 200 μm.

The carrier thus obtained is preferably insulative and spherical, but the effect of the present invention is not lost even if it is conductive or non-spherical.

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,
It is possible to prevent contamination of the surface of the photoreceptor of the carrier.

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 powder generated from the toner component due to the collision with the carrier particles and the surface of the photoconductor is mainly due to the relatively fragile component having a low molecular weight, and therefore, 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.

At least one selected from styrene-based monomers, ester-based monomers such as acrylic acid and methacrylic acid is an essential component as a monomer for obtaining the polymer of the main component resin of the toner. It is preferably a polymer. 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, 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, dimethylmino 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 dihydric 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 phthalate. Examples thereof include acid 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 plasticity 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 special Mg and Zn are preferable.

Examples of these polyvalent metal compounds include, for example, fluorides, chlorides, chlorates, bromides, iodides, oxides, hydroxides, sulfides, sulfites, sulfates, selenides, and tellurium of the above various elements. Compounds, 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-based 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 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, the high-molecular weight polymer component is first polymerized by polymerization so that one of the low-molecular weight polymer components is first produced, and then the produced one polymer component is treated with the other polymer component. 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 generate 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 of the present invention has a glass transition of 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. Is desirable. 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. Further, a polyester resin or an epoxy resin may be included.

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. Carbon black, nigrosine dye (CI No.50415)
B), aniline blue (CINo.50405), calco oil blue (CINo.azoic Blue3), chrome yellow (CI
No.14090), Ultramarine Blue (CINo.77103),
DuPont Oil Red (CINo.26105), Quinoline Yellow (CINo.47005), Methylene Blue Chloride (C.
I.No.52015), Phthalocyanine Blue (CI No.7416)
0), Malachite Green Oxalate (CI No.4200
0), lamp black (CINo.77266), rose bengal (CINo.45435), mixtures thereof, and the like. 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.

As the magnetic material, a metal or alloy exhibiting ferromagnetism such as ferrite, magnetite or other iron, cobalt, nickel or the like, a compound containing these elements, or an appropriate heat treatment containing no ferromagnetic element is used. Mention may be made of alloys which become magnetic, 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.

As the fixability improver, for example, polyolefin, fatty acid metal salt, fatty acid ester and fatty acid ester wax, partially saponified aliphatic ester, higher fatty acid, higher alcohol, liquid or solid paraffin wax, polyamide wax, polyhydric alcohol ester, Silicon varnish, aliphatic fluorocarbon, etc. 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 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 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). Company), Talanox 500 (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 size can be obtained by spraying a product melted and kneaded by an erostruder in a molten state with a spray dryer or by 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 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.

〔Example〕

Examples of the present invention will be described below, but the present invention is not limited thereto.

(Manufacture of Carrier) (1) Carrier 1 8 parts by weight of condensation reaction type silicone resin "SR-2411" (manufactured by Toray Silicone Co., Ltd.) was used in a fluidizing bed apparatus to obtain spherical steel-zinc ferrite particles having an average particle size of 100 μm ( 100 parts by weight (manufactured by Nippon Iron Powder Co., Ltd.) was sprayed and further heat-treated at 200 ° C. for 1 hour, and the agglomerates were sieved to obtain a carrier 1 having a volume average particle diameter of 102 μm and coated with a silicone resin.

(2) Carrier 2 Carrier 2 having a volume average particle size of 82 μm was obtained in the same manner as Carrier 1 except that “SR-2410” and spherical copper-zinc ferrite particles having an average particle size of 80 μm were used as the condensation reaction type silicone resin. .

(3) Comparative Carrier (1) A carrier obtained by coating the spherical copper-zinc ferrite particles of Carrier 1 with a styrene-methyl methacrylate copolymer resin is used as Comparative Carrier (1).

(4) Comparative carrier (2) Iron powder particles EFV250 / 400 (manufactured by Nippon Iron Powder Co., Ltd.) are used as a comparative carrier (2).

(Synthesis of Toner Resin) Synthesis Example-1 Toluene 50 is placed in 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.
0 ml was charged, 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 of 240 g of styrene, 60 g of n-butyl acrylate 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 solution of 452 g of styrene, 35 g of α-methylstyrene, 105 g of n-butyl acrylate, 35 g of methyl methacrylate, 73 g of monoacryloyloxyethyl succinate, and 35 g of benzoyl peroxide was dropped into the flask having the high molecular weight polymer solution. While carrying out the polymerization reaction. 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 at the reflux temperature for 2 hours while stirring.

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

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 found to have maximum values at 9.5 × 10 ³ and 2.4 × 10 ^5. It was a bimodal distribution. The weight average molecular weight (Mw) was 112,000 Mw / Mn was 12.5.

Synthesis Example-2 165 g of styrene, 135 g of n-butyl methacrylate and 0.9 g of benzoyl peroxide as high molecular weight polymer components,
As low molecular weight polymer components, 265 g of styrene, 70 g of α-methylstyrene, 245 g of n-butyl methacrylate, 70 g of methyl methacrylate, 50 g of monoacryloyloxyethyl isophthalate, 35 g of benzoyl peroxide, and 22 g of zinc acetate as a metal compound were used. Is Synthesis Example-1
Resin-B was obtained in the same manner as in.

This resin-B had the maximum values of the molecular weight distribution at 7.6 × 10 ³ and 2.2 × 10 ⁵ , and had Mw 98,000 and Mw / Mn = 14.1.

Synthesis Example-3 170 g of styrene as a high molecular weight polymer component, 30 g of butyl acrylate, 0.4 g of benzoyl peroxide, 480 g of styrene as a low molecular weight polymer component, α-methylstyrene
40 g, butyl acrylate 120 g, methyl methacrylate 8
0 g, monoacryloyloxypropyl succinate 80
Resin C was obtained in the same manner as in Synthesis Example-1 except that 32 g of benzoyl peroxide and 13.0 g of magnesium oxide were used as the metal compound.

The maximum value in the molecular weight distribution of Resin-C is 8.8 × 10 ³ and 4.9
× 10 ⁵ , and the weight average molecular weight (Mw) is 127,000, Mw
/ Mn was 15.0.

Synthesis Example-4 styrene 280g as a high molecular weight polymer component, 2-ethylhexyl acrylate 80g, methyl methacrylate 40g, benzoyl peroxide 1.6g, styrene 350g as a low molecular weight polymer component, α-methylstyrene 60g, 2-ethylhexyl acrylate 90g , Methyl methacrylate 60
g, monoacryloyloxypropyl isophthalate 40
Resin D was obtained in the same manner as in Synthesis Example 1 using 10 g of benzoyl peroxide and 10 g of zinc oxide as a metal compound.

The maximum value of the molecular weight in the resin-D molecular weight distribution is 6.1 x 1
It was 0 ³ and 1.8 × 10 ⁵ . Mw is 115,000 and Mw / Mn is 19.2.
Met.

Synthesis Example-5 Styrene 225 g as high molecular weight polymer component, n-butyl acrylate 60 g, monoacryloyloxyethyl succinate 15 g, benzoyl peroxide 0.9 g, low molecular weight polymer component styrene 437 g, α-methylstyrene
56 g, n-butyl acrylate 112 g, methyl methacrylate 35 g, monoacryloyloxyethyl succinate 6
Resin-E was obtained in the same manner as in Synthesis Example-1 except that 0 g of benzoyl peroxide and 8.0 g of zinc oxide were used as the metal compound.

The maximum molecular weight in the resin-E molecular weight distribution is 9.3 x 1
0 ³ and 3.2 × 10 ⁵ , and Mw was 126000 and Mw / Mn was 14.0.

Synthetic Example-6 180 g of styrene, 60 g of n-butyl acrylate, 60 g of methyl methacrylate and 0.9 g of benzoyl peroxide as high molecular weight polymer components, 350 g of styrene as low molecular weight polymer components, 350 g of styrene, 35 g of α-methyl styrene and 105 g of n-butyl acrylate. Resin F was obtained in the same manner as in Synthesis Example-1 except that 105 g of methyl methacrylate, 70 g of monoacryloyloxyethyl succinate, 35 g of benzoyl peroxide and 8.0 g of zinc oxide were used as the metal compound.

The maximum values of the molecular weight of Resin-F were 9.4 × 10 ³ and 2.6 × 10 ⁵ , and Mw was 115,000 and Mn was 12.8. (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 value of Resin-G is 9.1 × 10 ³ and 2.4 × 10 ⁵ , and Mw is 10
8,000 and Mw / Mn were 12.7.

Comparative Example 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, while stirring and heating this system to the boiling point of toluene, Solution polymerization was carried out while dropwise adding a mixture of 50 g of succinic acid monoacryloyloxyethyl ester and 10 g of benzoyl peroxide as a polymerization initiator over 2.5 hours.

After the dropping, the mixture was aged for 1 hour with 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.
-Butyl-succinic acid monoacryloyloxyethyl ester copolymer-resin which is a reaction polymer of zinc oxide-H
Got

Comparative Synthetic Example-3 Put 90 g of xylene 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 substituting with nitrogen gas, A solution prepared by dissolving 1.2 g of benzoyl peroxide in 10 g of xylene 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 to separate the precipitate, which was thoroughly dried at 50 ° C. Resin-I thus obtained had Mw / Mn of 27 and Mw of 233,000.

(Preparation of Toner) 100 parts by weight of each of Resins-A to F obtained in Synthesis Example-1 to Synthesis Example-6, carbon black ("Mogal L",
10 parts by weight of Cabot, 2 parts by weight of polypropylene (Viscor 660P, manufactured by Sanyo Kasei Co., Ltd.), and Wax
-E (manufactured by Hoechst) 2 parts by weight are 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. Then, classification was carried out to obtain toners 1 to 6 according to the present invention having an average particle size of 11.0 μm.

(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) Resin-H100 parts by weight and carbon black (diamond black)
SH: Mitsubishi Kasei Co., Ltd.) (5 parts by weight) 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 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).

(Preparation of Developer of the Present Invention) Example-1 49.75 parts by weight of Toner 1 according to the present invention and 0.25 parts by weight of hydrophobic silica (Aerosil R-972, manufactured by Aerosil Co., Ltd.) were mixed, and then Carrier 1 according to the present invention was mixed. Further mixed with 950 parts by weight to obtain a developer-1 of the invention.

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 formed of Teflon (polytetrafluoroethylene manufactured by DuPont), and the surface layer is a silicone rubber "KE-1300RTV" ( A toner image formed by the 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., and a linear velocity of 200 mm /
The operation of fixing at a linear pressure of 0.8 kg / cm and a nip width of 8.0 mm was repeatedly performed at each temperature by gradually increasing the set temperature of the heat roller by 5 ° C. within the range of 100 to 240 ° C. Kimwipe rubbing was performed on the fixed image, and the lowest setting temperature for the fixed image showing sufficient rubbing resistance 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 The operation of sending a blank transfer sheet to the fixing device under the same conditions and visually observing whether or not the toner is soiled is repeated by gradually increasing the set temperature of the heat roller of the fixing device. The lowest setting temperature at which the toner stains was set 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, 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 at the beginning and end of the 100,000 times development process and the cleaning blade 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 the white background with the original 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 performance: Cleaning performance was measured by cleaning the surface of the photoreceptor with a cleaning member. The surface of the photoconductor after cleaning was observed and judged by the presence or absence of adhered matter.

The results are shown in Table 1.

Example 2-6 As in Example-1, toners 2 to 6 according to the present invention and hydrophobic silica are mixed and then mixed with a carrier to form a developer-2 to.
6 was obtained and tested in the same manner as in Example-1. The results are shown in Table 1 below.

Comparative Example-1 5 parts by weight of the comparative toner (1) and 95 parts by weight of the comparative carrier (2) 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 4 parts by weight of Comparative Toner (2) and 96 parts by weight of Comparative Carrier (2) were mixed to prepare Comparative Developer- (2).
Tested as in 1. The results are also shown in Table 1.

Comparative Example-3 10 parts by weight of Comparative Toner (3) and 90 parts by weight of Comparative Carrier- (2) were mixed to prepare Comparative Developer- (3).
The test was conducted in the same manner as in 1. The results are also shown in Table 1.

Comparative example-4 Comparative toner- (4) was prepared by mixing 5 parts by weight of comparative toner (1) and 95 parts by weight of comparative carrier (1), and Example-1 was prepared.
Tested in the same manner as. The results are also shown in Table 1.

As shown in Table 1, in the developers 1 to 6 of the present invention, the low temperature fixability, the offset resistance and the blocking resistance are excellent, the fixable range is wide, and the ambient temperature and normal humidity and the high temperature and high humidity are the environmental conditions. Even under, fog does not occur, the cleaning property is also good, there is no fusion to the carrier, the photoreceptor surface cleaning blade, excellent triboelectrification, durability for a long period of stable and clear image, It was excellent in resistance to temperature and humidity.

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. Comparative developer- (4) is inferior in durability at 15,000 sheets under normal temperature and normal humidity and 8,000 sheets under high temperature and high humidity.

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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 coating in which a magnetic substance surface is coated with a silicone resin. An electrostatic latent image developer containing carrier particles (B), wherein 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 the molecular weight distribution In the above, 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 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), and a polyvalent metal compound. A polymer obtained by reacting the silicone resin Electrostatic latent image developer, which is a condensation reaction type silicone resin. General formula (A) (In the formula, R ₁ is H or CH ₃ , L is a divalent linking group having 3 or more carbon atoms and having an ester bond in the molecular chain,
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.