JPS63271476A - Developer for negative charge latent image - Google Patents

Abstract

PURPOSE:To improve the flowability and electrostatic charge stability and transferability of a developer by incorporating positive chargeable fine silica particles and zinc oxide powder into the developer. CONSTITUTION:The developer consists of a coated carrier, nonmagnetic toner, the positive chargeable fine silica particles and the zinc oxide powder. The fine silica particles subjected to a surface treatment with an amino modified silicone compd. (e.g.: amino modified silicone resin) can be used for the above- mentioned silica and the powder of ZnO or Zn2O can be used for the zinc oxide. The carrier prepd. subjecting the particles of a magnetic material (e.g.: copper- zinc ferrite) to a surface treatment with a silicone or fluorine compd. is usable for the carrier and the toner prepd. by adding a coloring agent, fixability improving agent, charge control agent, etc., into a binder (e.g.: styrene-n-butyl acrylate copolymer) is usable for the toner.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention is directed to the use of electrophotographic methods, electrostatic recording methods, electrostatic printing methods, etc., in which a negative photoreceptor formed on the surface of an organic photoreceptor made of an organic photoconductive semiconductor is used. The present invention relates to a dry developer for developing a latent charge image.

[Background of the invention]

Generally, in electrophotography, a photoreceptor having a photosensitive layer made of a photoconductive material is given a uniform electrostatic charge, and then an electrostatic latent image is formed on the surface of the photoreceptor by performing image exposure. This electrostatic latent image is developed with a developer to form a toner image. The obtained toner image is transferred to a transfer material such as paper and then fixed by heating or pressure to form a copy image.

As photoreceptors, selenium photoreceptors, zinc oxide photoreceptors, cadmium sulfide photoreceptors, and organic photoreceptors are known, but selenium photoreceptors tend to crystallize in high-temperature environments, resulting in poor heat resistance and poor sensitivity. The problem is that the characteristics deteriorate and the image becomes unclear. Furthermore, with zinc oxide photoreceptors and cadmium sulfide photoreceptors, their photosensitive characteristics tend to deteriorate early due to image exposure, and they also cause rippling, resulting in unclear images and poor durability, and are also toxic to the human body. is to blame.

On the other hand, organic photoreceptors made of organic semiconductors have the above-mentioned drawbacks, but have advantages such as good film forming properties, low manufacturing costs, high sensitivity, durability, heat resistance, and no toxicity to the human body. It is a preferred photoreceptor.

Generally, a one-component developing method and a two-component developing method are known as methods for developing an electrostatic latent image formed on the surface of a photoreceptor. In the former one-component developing method, a one-component developer consisting of a magnetic toner containing a magnetic material etc. dispersed in a binder resin is used, but since it is made of a magnetic toner and does not have CaI77, it has poor triboelectric charging properties and is not easily triboelectrified. Toner with a small electric charge or toner with an opposite electric charge coexists, resulting in unstable developability and the inability to obtain a stable image.
This has the disadvantage that toner also adheres to non-image areas on the photoreceptor, causing fog.

In addition, the magnetic substance contained in the magnetic toner is hydrophilic,
In a humid environment, triboelectric charges tend to leak, and as a result, the layer-like transfer to the transfer material deteriorates in the transfer process and the toner transfer rate decreases. As a result, the image density decreases and the image 2iL is distorted.

On the other hand, the two-component developer used in the latter two-component development method is composed of a toner and a carrier, and the carrier can impart triboelectric charges of appropriate polarity and appropriate amount to the toner. It is possible to impart significantly superior triboelectric charging properties compared to the above-mentioned -component developer. Further, by selecting a carrier having desired characteristics, it becomes possible to control the amount of charge of the toner to a considerable extent, and it is possible to stably obtain clearer images.

However, when using a two-component developer.

There are inherent problems associated with two-component developers, such as deterioration of the carrier, deterioration of the photoreceptor and image quality due to abrasion of the carrier on the surface of the photoreceptor, carrier scattering, and toner scattering.

That is, in a two-component developer, when toner and carrier are stirred and mixed in a developing device to make them homogeneous, mechanical impact force causes
Some of the toner particles are crushed to form toner slag, which accumulates on the surface of the carrier particles and interferes with proper frictional charging of the carrier and toner. After long-term use, the amount of charge on the toner decreases, resulting in fogging. , toner scattering due to a decrease in electrostatic adhesion between the toner and carrier, and a decrease in image density and image disturbance due to a decrease in transferability to a transfer material, resulting in a significant decrease in durability.

In addition, when a magnetic brush is formed on a developer carrier using a two-component developer to develop a latent image on a photoreceptor, the developer easily scratches the photoreceptor and damages the photoreceptor. A part of the image is missing (image dropout) or the developed toner image is scratched, resulting in a dark and light striped pattern (sweeping) along the development direction.
occurs. This phenomenon becomes more noticeable when the fluidity of the developer is poor.

In a two-component developer using a negatively chargeable toner, problems caused by the two-component developer are addressed, for example, by adding negatively chargeable hydrophobic silica fine particles to the toner as described in JP-A No. 45-5782. A method of adding and mixing is adopted. However, when such negatively chargeable silica fine particles are added and mixed into a positively chargeable toner, the positive triboelectric chargeability of the toner is inhibited, resulting in an unclear image with a lot of fog.

Taking these circumstances into consideration, a method is known in which the surface of silica fine particles, which are originally negatively chargeable, is modified to be positively chargeable by treating the surface and added to toner.
3-22447 and JP-A-58-185405 disclose inorganic fine particles treated with an aminosilane coupling agent, and JP-A-59-187359 discloses silicic acid fine particles treated with silicone oil having an amine in the side chain. It has been known. Although it is possible to obtain clear images with relatively little fog by adding and mixing such positively chargeable silica fine particles into toner, a completely satisfactory solution has not yet been reached. It has not yet been possible to solve all the problems caused by interactions with particles.

That is, a charge control agent is usually added to a toner in order to impart desired polarity and triboelectric charge amount. The method of addition is to mix it with the binder resin, knead it and disperse it into the toner. However, the materials used as blue electricity control agents are generally dyes and pigments, which are susceptible to NRA, thermal decomposition during kneading, and deterioration due to temperature and humidity, and furthermore, it is difficult to uniformly disperse them into the binder resin. If a two-component developer is prepared using a toner containing such a charge control agent, which makes it difficult to impart stable chargeability to the toner over a long period of time, the triboelectricity of the toner will quickly decrease during long-term use. This causes fogging and a decrease in image density. moreover,
When toner and carrier are stirred in a developer container, crushed toner particles and poorly dispersed charge control agents are liberated, and these liberated substances adhere and accumulate on carrier particles, the surface of the photoreceptor, or the developer carrier. This causes contamination, impairs the triboelectric charging properties of the l-ner, and also causes deterioration of the characteristics of photoreceptors, reducing their durability.

Addition of the positively chargeable silica fine particles may be considered as a means to solve the problems caused by such charge control agents, but the improvement is only slight. On the contrary, if the positively chargeable silica fine powder is used, the cleaning effect of the cleaning blade on residual toner on the photoconductor is reduced, and the initial chargeability of the toner and carrier under high temperature and humidity conditions is deteriorated, resulting in poor charging start-up. Therefore, fogging is likely to occur in the initial image. Furthermore, positively charged silica fine particles are released from the toner surface and adhere to the carrier particle surface due to the mechanical force received in the developing device, and especially in coated carriers,
Positively charging fine silica particles are embedded in the surface of the carrier and accumulate therein, reducing the triboelectric charging properties of the carrier and significantly reducing the durability of the developer.

[Purpose of the invention]

The present invention has been made in order to solve the above-mentioned conventional problems as much as possible.

That is, the purpose of the present invention is to provide (1) a developer for developing a negative charge latent image that has high triboelectric chargeability of the toner, is stable, and provides a clear image without fog; (2) has good transferability. (3) A negative charge latent image developer that has good developer fluidity and can achieve uniform development and produce images without sweeping marks; (4) ) Negative charge latent image developer with excellent environmental resistance and stable triboelectricity with good initial rise even under high temperature and low temperature and low humidity environmental conditions; (5) carrier made from crushed toner particles; (6) Negative charge latent image developer that avoids contamination of the surface and photoconductor surface and has good durability; (6) Negative charge latent image developer that has a good cleaning effect when cleaning residual toner on the photoconductor surface with a cleaning blade. Our goal is to provide the following.

[Means to achieve the purpose]

The above aspects of the present invention can be achieved by a negatively charged latent image developer containing a coated carrier, a nonmagnetic toner, positively charged silica fine particles, and zinc oxide powder.

[Actions and effects of the present invention]

According to the developer of the present invention, a negative charge latent image can be developed well without sacrificing the advantages of an organic photoreceptor, and images with good image quality such as high image density without fogging can be obtained. It also has good operational durability.

In the present invention, surface-treated positively chargeable silica fine particles are added to the toner in order to improve the fluidity of the developer, impart a stable and high positive triboelectric charge to the toner, and improve moisture resistance. . This makes the photoreceptor less likely to be damaged, and it is possible to largely eliminate image omissions and image sweeps.

In the present invention, zinc oxide fine particles are added to the toner in addition to the positively chargeable silica fine particles. By blending the developer in this manner, the developer exhibits even more excellent triboelectric charging properties, and even during long-term use, fluctuations in electrostatic charges are reduced, and durability can be improved. That is, by adding zinc oxide particles, the zinc oxide particles are interposed between the toner and the carrier particles, and the generation and release of crushed toner particles are prevented from contaminating the carrier and the surface of the photoreceptor. It is considered that Furthermore, the hardness of the zinc oxide particles is about 4 to 5 on the Mohs hardness scale, so that the cleaning blade is less likely to be damaged, and cleaning defects caused by the positively charged silica particles can be prevented. Furthermore, since the triboelectric charging efficiency of the toner and carrier is significantly improved, even under high temperature and high humidity environmental conditions, the initial charging rise is good and a good image can be obtained without fogging.

Further, the present invention is directed to a coated carrier, which helps prevent the adhesion of loose toner scum and particulates added to the toner.

In addition, the developer of the present invention has a coated carrier, a non-magnetic toner, positively charged silica particles, and zinc oxide particles as constituent elements, so that the developer has good fluidity and charging stability, and the developer has a magnetic brush. As the abrasion of the photoreceptor due to
Good images that are as good as the initial images can be obtained, and the developer has excellent environmental resistance and durability.

[Specific structure of the invention]

The positively chargeable silica fine particles in the present invention belong to the following categories. That is, 0.28 g of silica fine particles left overnight at a temperature of 20° C. and a relative humidity of 60% and 19.8 g of uncoated ferrite particles (for example, F-150 manufactured by Nippon Tetsuko Co., Ltd.) were mixed. In the above environment, the silica particles were shaken for 5 minutes in a glass sample container with a volume of about 20 ee, and then the triboelectric charge of the silica particles was determined by a conventional blow-off method using a stainless steel cell with a 635 mesh screen. It measures the amount of friction that results in a positive triboelectric charge.

The positively chargeable silica fine particles have a triboelectric charge of +10 μC/g or more, particularly +30 μC in the above measurement.
/g or more is preferable. If the amount of triboelectric charge is too small, the positive triboelectricity of the non-magnetic toner deteriorates and the amount of triboelectricity decreases, resulting in fogging or
The durability of the developer may decrease.

The positively chargeable silica fine particles are surface-treated silica fine particles. Examples of substances that can be used for the surface treatment include amino-modified silane coupling agents, amino-modified silicone oils, amino-modified silicone varnishes,
Amino-modified silicone compounds such as amino-modified silicone rubber, amino-modified silicone resin, or cured products thereof can be preferably used. Amino-modified silicone varnishes, amino-modified silicone rubbers, amino-modified silicone resins, or cured products thereof are preferred because they provide particularly excellent positive chargeability, moisture resistance, and durability. According to the treated silica fine particles, due to the presence of amino groups, the silica fine particles have excellent positive chargeability, and moreover, the functional groups of the silicone compound and the hydrophilic groups such as hydroxyl groups present on the surface of the silica fine particles are combined. are strongly bonded together, resulting in silica fine particles that are excellent in moisture resistance and durability, and have stable positive triboelectric charging properties that are not affected by environmental conditions.

As the amino-modified silicone varnish preferably used to obtain positively chargeable silica fine particles, for example, amino-modified methyl silicone varnish, amino-modified phenylmethyl silicone varnish, amino-modified phenyl silicone varnish, etc. can be used, and in particular, amino-modified The amino-modified silicone varnish, which is preferably a methyl silicone varnish, has a Tll unit, a D day unit, an M day unit, and a group in which some of the organic groups present in each of these units have an amino group, as shown in the following structural formula. It is a three-dimensional polymer consisting of units substituted with , and containing 10 to 90 mol%, preferably 30 to 80 mol% of T day units. If the proportion of the T'1 unit is too small, the stability of the adhesive lick triboelectric charging property may decrease, and the carrier may be contaminated, resulting in a decrease in the durability of the developer. On the other hand, if the proportion of the T-th unit is too large, the cleaning blade becomes excessively hard, which makes the cleaning blade more likely to be damaged, and as a result, cleaning defects are more likely to occur.

[T1 unit] CD'' unit] [M11 unit] RI5 ■ RI-5i-0- h... R11, R12, RI, R14, RI in each unit
S and RI each represent an alkyl group such as a methyl group or an ethyl group, an aromatic group such as a phenyl group, an organic group such as a polyether group, a hydroxyl group, or an amino group.

Specifically, it is a substance having a chemical structure as shown by the following structural formula (1), for example.

Structural formula (1) where R■7. R" represents an organic group such as a methyl group or a phenyl group.

The amino-modified silicone rubber preferably used to obtain positively chargeable silica particles includes, for example, a D" unit represented by the following structural formula, and a group in which some of the organic groups present in the unit have an amino group. It is a long chain polymer consisting of substituted units.

[D2121 single [[) 22 units] In each unit, R21, [(22, R25 is an alkyl group such as a methyl group or an ethyl group, an aromatic group such as a phenyl group, a polyether group, a hydroxyl group, an amino group, etc.) represents.

Further, in order to make the silicone rubber have a crosslinked structure, it is preferable to copolymerize a small amount of D'' units represented by the above structural formula.

The amino-modified silica resin preferably used to obtain positively chargeable silica particles has the T1 unit, the D''
It is a polymer consisting of the above-mentioned M11 unit and units in which a part of the organic group present in each of these units is substituted with a group having an amino group, and unlike silicone oil, it contains a large amount of T units. It is a polymer.

In the amino-modified silicone varnish, especially T1
The unit imparts good thermosetting properties, and furthermore, the T
1 unit, and in amino-modified silicone rubber, it has a cross@ structure especially with 2 D" units, and in amino-modified silicone resin, T
Each unit has many branches, making it a 1m structure, and
A cyclic structure is formed within the molecule. These results
Silica fine particles having a silicone compound as described above on the surface form a tough coating on the surface and have excellent impact resistance, moisture resistance, and mold releasability.

In addition, in 7-mino-modified silicone rubber, amino-modified silicone rubber, and 7-mino-modified silicone resin, there is a considerable amount of silanol groups having 011 groups without forming siloxane bonds. Siloxane bonds are formed through reactions such as dehydration condensation with functional groups present on the surface of the fine particles, or during the curing stage, and as a result, the film has even stronger properties.

Further, as a curing accelerator that can be used to accelerate the curing reaction, in the case of 7-mino-modified silicone fuss, for example, fatty acid salts such as zinc, lead, cobalt, and tin;
Amines such as triethanolamine and butylamino; etc. can be used. Among these, amines can be particularly preferably used. In addition, in the case of amino-modified silicone rubber, known vulcanizing agents can be used. Specifically, for example, benzoyl peroxide, bis-2
, 4-dichlorobenzoyl peroxide, di-butyl peroxide, dicumyl peroxide, and the like can be preferably used.

Furthermore, as the group having an amino group in the amino-modified silicone varnish, amino-modified silicone rubber, and amino-modified silicone resin, those represented by the following structural formula are preferable.

CHtc Hz N Hz -CH2(CH2L N H2 -CHx(CHz)z NH(CHI)3 NH2
As the amino/modified silane coupling agent used to obtain positively chargeable silica fine particles, for example, a compound represented by the following chemical formula is preferable.
zCH2S! (OCHi)iH3 H2N CH2CH2CHaS i (OC28s)
2CH.

HEN CH2CH2CHsSi(OCHs)2CH1 H2N CH2CH2N HCH2CH2CH2S i
(OCI(3)zH2N CH2CH2N HCH2
CH2CH2si(0,CH2)3-CH2CH2Si
(OCH3)s Hs C20COCH2CH2N HCHz CH2C
H2--Si(OCHs)s (HsCz)2NcHzc)(zcHzsi(OCHs
) As the 7-mino-modified silicone oil, for example, one represented by the following general formula (A) can be used.

General formula (A) where R'' represents an alkylene group, 7-aryl group, aminoalkylene group, etc., R42 and V R43 each represent a hydrogen atom, a hydroxyl group, an alkyl group, a 7-aryl group, etc., and x , y each represent an integer of 1 or more.

In addition, it is preferable that the amino-modified silicone oil has an amino-7 equivalent value within the range of 300 to 10,000. If the value of 7-min equivalent is too small, the effect of imparting positive chargeability by silica particles is small, resulting in fogging. On the other hand, when the value of 7-amino equivalent is too large, the silica particles tend to transfer and adhere to the carrier particles, and the durability of the image forming agent may be reduced.

Examples of commercially available 7mm/modified silicone oils that can be preferably used include those listed in Table 1 below.

The primary particles of silica fine particles (particles separated into individual unit particles) whose surface is treated with the above-mentioned compound are:
It is preferable that the average particle size is within the range of 3-μ to 2-μ.

In addition, the silica fine particles are fine particles having a 5i-0-Si bond, and may be manufactured by either a dry method or a wet method, but the point is that the fluidity and moisture resistance of the developer are good. Silica particles produced by a dry method are preferred, and silica particles produced by vapor phase oxidation of silicon halogen compounds are particularly preferred.In addition to silicon dioxide (silica), silica particles include aluminum silicate, aluminum silicate, Although fine particles made of silicates such as sodium silicate, calcium silicate, potassium silicate, zinc silicate, and magnesium silicate may be used, those containing 85% by weight or more of 5ift are preferable.

As a method for treating the surface of silica fine particles with the above compounds, known techniques can be used. Specifically, for example, using a fluidization bed device, a solution of the above compound components dissolved in a solvent can be used. A method may be used in which the coating is spray-coated onto fine silica particles and then heated and dried to remove the solvent and cure the coating.

The particle size of the positively chargeable silica fine particles surface-treated (coated) with the above-described compound is such that the average particle size of the primary particles is 3 μm to 2 μ−1, particularly 5 μm to 500 μm.
It is preferable that it is within the range of sμ, and BE
The specific surface area measured by the T method is preferably 20 to 500 m"7g. If the average particle size is too small or the specific surface area is too large, fine silica particles may slip through when cleaning using a blade-type cleaning device, for example. This may result in poor cleaning.

On the other hand, when the average particle size is too large or the specific surface area is too small, the fluidity of the developer decreases, resulting in poor developability, which may result in a decrease in image density or the occurrence of streaks in the image.

The silica powder consisting of the positively chargeable silica particles is added to and mixed with the non-magnetic toner powder, thereby being attached and retained on the surface of the non-magnetic toner particles.

The content ratio of the positively chargeable silica fine particles is preferably 0.1 to 5 times the weight of the non-magnetic toner, particularly 0.1 to 5 times the weight of the non-magnetic toner.
Preferably it is 2% by weight. When the content of positively chargeable silica fine particles is too small, the fluidity of the developer may decrease, resulting in poor triboelectric charging properties of the nonmagnetic toner, and the nonmagnetic toner does not have an appropriate amount of positive charge. It becomes difficult to apply the image, and fogging or sweeping lines may occur in the image. In addition, when the content ratio is excessive, some of the positively charged silica particles may exist in a free state from the non-magnetic toner particles, and as a result, the free positively charged silica particles may adhere to and transfer to the carrier particles. Otherwise, it may adhere to and accumulate on the developer carrier, regulation blade, etc., and eventually the triboelectric charging properties of the non-magnetic toner will deteriorate at an early stage, making it difficult to apply an appropriate amount of positive charge, resulting in fogging and a decrease in image density. This may occur.

The zinc oxide used in the present invention includes zinc oxide (ZnO) and zinc suboxide (ZntO), which is considered to be a 1=1 solid solution of metallic zinc and ZnO. Zinc oxide (
Z no ) is by thermally decomposing zinc oxalate at 400℃, or
A pure product can be obtained by heating and dehydrating zinc hydroxycarbonate, but it can also be produced by oxidizing industrially by burning metal zinc.Zinc oxide (ZnzO) is produced by heating zinc oxide with carbon or metal zinc under pressure. Alternatively, it can be obtained by heating zinc oxide in vacuum or in a nitrogen stream.

The particle size of the zinc oxide particles according to the present invention is preferably such that the average particle size of the primary particles is 0.01 to 3.0 g, and the specific surface area by BET method is 1.0 to 30 m''7 g. When the average particle size is too small or the specific surface area is too large, cleaning defects are likely to occur during blade-type cleaning, while on the other hand, when the average particle size is too large or the specific surface area is too small, the fluidity of the developer decreases. This may deteriorate the developability, resulting in a decrease in image density or the occurrence of sweeping lines in the image.

The zinc oxide particles are attached and retained on the surface of the non-magnetic toner particles by being mixed as a powder with the non-magnetic toner particles.

The content ratio of the zinc oxide particles is 0.01% of the non-magnetic toner.
If the content of zinc oxide particles is too small, preferably 5% by weight, and particularly preferably 0.05% to 2% by weight, the fluidity of the developer may decrease, resulting in The triboelectric charging properties of the magnetic toner become poor, making it difficult to apply a positive charge of an appropriate band ThJi to the non-magnetic toner, and blurring or sweeping of images may occur. In addition, when the content ratio is excessive, some of the zinc oxide particles may exist in a free state from the non-magnetic toner particles, and as a result, the free zinc oxide particles may adhere to and transfer to the carrier particles, or the developer may It adheres and accumulates on the carrier, regulating blade, etc., and eventually the triboelectric charging properties of the non-magnetic toner become poor, making it difficult to apply an appropriate amount of positive charge to the non-magnetic toner, resulting in fogging and poor image density. Deterioration may occur.

The non-magnetic toner constituting the negative charge latent image developer of the present invention is
Basically, they are particles that contain colorants and other additives in a binder resin, and their average particle size is 5 to 5.
Preferably, it is 20 μ-.

Other additives that can be used include, for example, fixability improvers, charge control agents, and the like.

The binder resin constituting the non-magnetic toner is not particularly limited, and various resins can be used.

Specifically, for example, polystyrene resin ζ styrene-acrylic copolymer, polystyrene-butadiene resin,
Polyester resin, epoxy resin, polyamide resin, polyurethane tJI resin, etc. can be used. In particular, styrene-acrylic copolymers can be preferably used, and among them, styrene monomers and acrylic acid can be obtained by polymerization with L (or its ester and I//or metal acrylic acid or its ester). Copolymers can preferably be used.

In the styrene-acrylic copolymer, it is preferable that the styrene component is contained in a proportion of 95 to 60 il% of the copolymer, and when the proportion of the styrene component is excessive, I; The non-magnetic toner may become brittle and the durability of the non-magnetic toner may be reduced. On the other hand, if the proportion of the styrene component is too small, the copolymer tends to adhere to the wall of the developing device, and as a result, the triboelectric charging properties of the nonmagnetic toner may be inhibited.

Specific examples of styrene monomers that can be used to obtain the styrene-acrylic copolymer include styrene, 0-methylstyrene, -methylstyrene,
p-methylstyrene, a-methylstyrene, p-ethylstyrene, 2,4-tmethylstyrene, 9-n-butylstyrene, p-t-butylstyrene, u-1-hexylstyrene, p-11-octyl Styrene, p"'n-7
Nylstyrene, p-n-7'silstyrene, p-n-dodecylstyrene, p-methoxystyrene, p-phenylstyrene, p-arylstyrene, 3,4-nochlorostyrene and the like can be mentioned. These monomers may be used alone or in combination.

Further, examples of the acrylic component that can be used to obtain the styrene-acrylic copolymer include acrylic acid, methyl acrylate, ethyl acrylate, aphrylmin-n-butyl, isobutyl acrylate, propyl acrylate, n-octyl acrylate, dodecyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, methyl a-chloroacrylate, methacrylic acid, methyl methacrylate, methacrylic acid Ethyl, propyl methacrylate, flln-butyl methacrylate, isobutyl methacrylate, n-octyl tutaacrylate, dodecyl methacrylate, lauryl tutaacrylate,
2-ethylhexyl methacrylate, stearyl ivy, ivy #! phenyl, a-methylene aliphatic monocarboxylic acid esters such as dimethyl 7-minoethyl methacrylate, and diethylaminoethyl methacrylate; acrylic acid or methacrylic acid derivatives; and others. These monomers may be used alone or in combination.

As a method for producing the styrene-acrylic copolymer, for example, a solution polymerization method, a suspension polymerization method, an emulsion polymerization method, etc. can be used.

Examples of coloring agents include carbon black and Phthalosi 7.
Nimp, Ru, Benzinone Yellow, Nigrosine dye, 7
Dyes and pigments such as niline blue, calco oil blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, malachite green offsalate, lamp black, and rose bengal can be used. These substances may be used alone or in combination, and the content of the colorant is usually preferably 1 to 15% by weight of the nonmagnetic toner.

As the fixability improver, for example, polyolefins, fatty acid esters and fatty acid ester waxes, solid paraffin waxes, amide waxes, silicone varnishes, aliphatic fluorocarbons, and the like can be used.

As the charge control agent, for example, nigrosine dyes, metal complex dyes, ammonium salt compounds, aminotriphenylmethane dyes, polymers having amino groups such as styrene-dimethylaminoethyl methacrylate copolymer, etc. can be used. can.

As the coated carrier constituting the developer used in the present invention, carriers having various configurations can be used. Specifically, a coated carrier in which the surface of magnetic particles is treated with a silicone compound or a fluorine resin is preferred.

Examples of compounds used in the coated carrier include silicone compounds such as silane coupling agents, silicone oils, silicone varnishes, silicone rubbers, silicone resins, and cured products thereof; for example, vinylidene fluoride-ethylene tetrafluoride copolymers; tetrafluoroethylene,
Using fluorine-based resins such as methyl methacrylate-7-tacrylic acid-1,1-nohydroxyperfluoroethyl copolymer, styrene-methacrylic acid-1,1,3-)lyhydroxyperfluoro-rhoprobyl copolymer; Preferably, zero or more substances may be used alone, or a plurality of substances may be used in an appropriate combination.

Among these substances, silicone compounds are particularly preferably used because they provide excellent developability and chargeability, and among them, silicone varnishes, silicone rubbers, silicone resins, or cured products thereof are particularly preferably used. In coated carriers obtained using such silicone-based compounds, the surface energy thereof is considerably reduced, and as a result, transfer of toner material or positively charged silica fine particles to carrier particles becomes possible.

Further, as silicone varnishes, silicone rubbers, and silicone resins, those having an organic group such as an alkyl group or an aromatic group as the h11 unit are preferable, and those having an organic group such as a methyl group or a phenyl group are particularly preferable. Specific examples of silicone compounds having organic groups include dimethylpolysiloxane, methylphenylpolysiloxane, diphenylpolysiloxane, and modified products thereof. In particular, polysiloxanes having a methyl group or a 7-enyl group have excellent negative chargeability,
When the coated carrier obtained by melting this and the non-magnetic toner are tribo-electrified, a good positive tribo-charge can be imparted to the non-magnetic toner. By appropriately selecting the content ratio of methyl groups and phenyl groups among the above organic groups, it is possible to adjust the properties of the carrier coating, such as hardness, toughness, and triboelectric charging properties. There is an advantage that the conditions required for the non-magnetic toner used in combination are considerably relaxed, and the range of non-magnetic toners to be selected is wide.

Commercially available silicone varnishes include, for example, rs
R2101J, rsII99FJ, rsl1994J
, rsR2202J, rsE9140JrSH64
3,, rsH2047,, rJcR6100,, rJc
R6101” (manufactured by Toray Silicone Co., Ltd.), r
KR2F1'', [to R272,, [to R274,, rK
R216,, rKR280,, rKR282,, rKR
261, ``niR260, ``niR255J, rKR2
66J, rKR251J, rKR155, "K old 52
”, “R214,” “R220J, rX-40-
171t, rKR201'', rsA-4,, rKR5
202, rKR3093J, rEcloolJ (manufactured by Shin-Etsu Chemical Co., Ltd.), and the like.

Commercially available silicone rubber products include, for example, rsH
410,, rSH432,, rs11433J, rsH
740,, rSH35υ”, rs1175UJ, rs1
+841U,,rs111125U,,rs11160
3υ", "511685UJ, rsE955U,, rs
H502u, rSRX-440U, (manufactured by Toray Silicone), and the like.

Further, when forming a coated carrier using the silicone compound as described above, a curing agent may be used as required. Examples of such curing agent include benzoyl peroxide, 2,4-dichlorobenzoyl peroxide,
Peroxides such as dicumyl peroxide, ditertiary butyl peroxide, and tertiary butyl perbenzoate; Metal soaps such as lead, iron, cobalt, manganese, and zinc such as octylic acid and naphthenic acid; Organic amines such as ethanolamine : and so on.

The magnetic particles constituting the carrier include materials that are strongly magnetized in the direction of a magnetic field, such as iron, ferrite,
Particles made of ferromagnetic metals or alloys such as magnetite, iron, nickel, and cobalt, or compounds containing these elements can be used, and ferrite particles, which do not cause carrier scattering, are particularly preferred.

The method for producing the coated carrier is not particularly limited, but for example, a coating solution prepared by dissolving the coating components and a curing agent used as necessary in a solvent is applied to the surface of the magnetic particles, and then heated. Dry to remove the solvent by volatilization,
By heat curing the coating layer if necessary! 1!
can be sent.

The coating method is not particularly limited, but includes, for example, a dipping method in which powder of magnetic particles is immersed in a coating solution, a spray method in which the coating solution is sprayed onto the magnetic particles, and a method in which the magnetic particles are suspended using fluidized air. A fluidized bed method or the like can be used in which a coating liquid is sprayed onto the magnetic particles in the state.

As the solvent for the coating liquid, for example, toluene, xylene, acetone 7, methyl ethyl ketone, tetrahydro 7 run, dioxane, higher alcohol, or a mixed solvent thereof can be used.

The average particle size of the carrier is preferably 5 to 500 μm, particularly preferably 20 to 200 μm.
When the average particle size of the carrier is too small, a so-called carrier adhesion phenomenon occurs in which the carrier adheres to the electrostatic latent image and forms a fixed image, and as a result, the image may become unclear. When is excessive, image unevenness may occur. The average particle size (weight) of the carrier is a value measured using "r Microtrack" (manufactured by Nikkiso Co., Ltd.).

The organic photoreceptor according to the present invention is constructed by laminating a photosensitive layer in which a photoconductive semiconductor made of an organic compound is dispersed in a resin binder on a conductive support made of, for example, aluminum or stainless steel.

The photosensitive layer may include a carrier generating substance that absorbs visible light and generates charge carriers, such as an anthurone compound, perylene derivative, bisazo compound, phthalocyanine compound, etc., a styrene-methyl methacrylate copolymer, a polycarbonate resin, etc. , a carrier generation layer dispersed in a binder resin such as a silicone resin, and, for example, an oxadiazole derivative, a triarylamine derivative, a polyarylalkane derivative, a hydrazone derivative,
It is preferable to use a functionally separated photosensitive layer formed by combining a carrier transport layer containing a carrier transport substance that transports carriers generated in the carrier generation layer, such as a stilbene derivative or a styryl triarylamine derivative.

[Examples] Specific examples and comparative examples of the present invention will be described below, but the present invention is not limited to these examples.

(Manufacture of silica fine particles) (1) Silica fine particles AI (example) has the following D1 unit, the following ^[11Q1 position, and the following T' unit as constituent units, and the molar ratio of these is 4 = 1:5. and has a 0 group at the end, and 2 in a xylene solution with a concentration of 30% by weight.
A treatment liquid was prepared by dissolving 7-mino-modified silicone foam having a viscosity of 50 to 200 eps at 5°C in xylene.

(D' unit) (T' unit) [Go to 〇1 unit] Next, silica fine particles "Aerosil 200J (
(manufactured by Nihon 7ko Rosil Co., Ltd.) was placed in a mixer, and the amino-modified silicone rubber was sprayed on the silica fine particles at a ratio of 20% by weight.Then, the mixture was placed in a flask and heated to a temperature of 200°C while stirring. The solvent, xylene, was removed over a period of 5 hours at 0.degree. C., and the 7-mi/modified silicone fuss was subjected to a curing reaction, thereby obtaining surface-treated positively chargeable silica fine particles. This [Silica fine particles A
I.J.

The silica fine particles A1 have an average primary particle diameter of 12-
The specific surface area measured by μ and DET method is 110”/g.

Further, the amount of frictional electrification with the non-coated 7-elite particles "F-1501 (Nippon Tetsuko Co., Ltd. 91) is +F2 μC/g.

(2) Silica fine particles A2 (example) have the above D1 unit, the following D2 unit, and the following ^D2 unit as constituent units, the molar ratio of these is 5 = 2:3, and the viscosity at 25 ° C. is 6 A processing solution was prepared by dissolving in xylene an amino-modified silicone rubber having an average molecular weight of 10'cps and 7×10' and 2% by weight of benzoyl peroxide based on the amino-modified silicone rubber.

(1) 2 credits] C11゜ ! -0-Si-0- CI = CI! .

[^D2 units] C.I.

View 10-3i-0- C11, (C112), NH (C112), N112 Secondary, silica fine particles [Aeronol 300J (manufactured by Aeronol Co., Ltd.) were placed in a mixer, and the silica fine particles were
Surface-treated positively chargeable silica fine particles were obtained in the same manner as in the production of silica fine particles A1, except that the treatment liquid was sprayed in such a proportion that the amino-modified silicone rubber was 10% by weight. This is referred to as 1-silica fine particles A2J. The silica fine particles A2 have an average primary particle diameter of 7-μ,
The specific surface area determined by the BET method is 145 m27 g. Further, the amount of frictional electrification with non-coated ferrite particles rF-150J (manufactured by Nippon Tetsuko Co., Ltd.) is +162 μC/g.

(3) Silica fine particles A3 (Example) have the above D1 unit, the above D2 unit, the following ^0 units, and the above TI unit as constituent units, and the molar ratio of these is 4.5: 1.5
: 2 : 2 amino-modified silicone resin and 0.5% by weight based on this amino-modified silicone resin
A treatment solution was prepared by dissolving benzonel peroxide in xylene.

[^D3 units] CI+.

N.H.

Next, silica fine particles "Aerosil 200. (manufactured by Nippon Aerosil Co., Ltd.) were placed in a mixer, and a treatment liquid was sprayed onto the silica fine particles in a proportion such that the amino-modified silicone resin was 30% by weight. Silica fine particles A
1. Surface-treated positively chargeable silica fine particles were obtained in the same manner as in the production of . This is referred to as [silica fine particles A3J]. The silica fine particles A3 have an average primary particle diameter of 12
mμ, specific surface area measured by the IIET method is 82 m”7g.Furthermore, the amount of frictional electrification with uncoated ferrite particles rF-150J (Nippon Iron Powder Co., Ltd. 91) is +81 μC/g.

(4) Silica fine particles A4 (Example) Silica fine particles [
Aerosil 200J (manufactured by Nippon Aerosil Co., Ltd.) 100
A solution of amino-modified silicone oil dissolved in isopropyl alcohol (viscosity (25°C)) was added to the silica fine particles in a closed Henschel mixer heated to
= 1200 cps, 7 minoequivalent = 3500) was stirred at high speed while spraying at a rate such that the processing amount of amino-modified silicone oil was 2.0% by weight, and then dried at a temperature of 150°C, thereby improving the surface Treated positively chargeable silica fine particles were obtained. This [Silica fine particles A4J
shall be. The silica fine particles A4 have an average primary particle diameter of 12-μ and a specific surface area of 120 mm by the BET method, 7 g.
It is. *Uncoated 7-elite particles IF-1501 (
The amount of frictional electrification with Nippon Iron Powder Co., Ltd. is +110 μC/g.

(5) Silica fine particles As (Example) Silica fine particles "
7 Aerosil 300J (manufactured by Nippon Aerosil Co., Ltd.) at 0°C.
The fine silica particles were placed in a closed-type Henschel mixer heated to a temperature of The mixture was stirred at high speed while being sprayed at a rate such that the treatment amount was 5.0% by weight, and then dried at a temperature of 120°C.
As a result, surface-treated positively chargeable silica fine particles were obtained. This is referred to as [silica fine particles A5J].

The silica fine particles A5 have an average primary particle diameter of 8 μm.
, the specific surface area according to the BET method is 151g + 7g.

Further, the amount of triboelectrification with uncoated ferrite particles rF-150J (Nippon Tetsuko Co., Ltd. 91) is +94 μC/g.

(6) Silica Fine Particles A6 (Comparative Example) Negatively chargeable silica fine particles [-972J (manufactured by Nippon Seven Engineering Logil Co., Ltd.) are referred to as silica fine particles A6. The amount of frictional electrification of this silica fine particle M6 with uncoated ferrite particles rF-150J (manufactured by Nippon Tetsuko Co., Ltd.) is 1200 μC/g.

(Characteristics of zinc oxide particles) (1) Zinc oxide fine particles B1 Zinc oxide (ZnO) fine particles "Sazex #40"
00J (manufactured by Sakai Chemical Industry Co., Ltd.; average particle size 0.83μ
Taki, BET value 5.0 import 27g) is set as B1.

(2) Zinc oxide fine particles B2 Zinc oxide (ZnO) fine particles "Sazex #20"
00, (manufactured by Sakai Chemical Industry Co., Ltd., 0.87g ring, [lET
Value 5. : (s2/g) is defined as B2.

(Manufacture of carrier) (1) 8 parts by weight of carrier C1 silicone varnish rSR-2101J (manufactured by Le Silicone Co., Ltd.) was added using a fluidized bed device.
10 of spherical copper-zinc ferrite particles (manufactured by Nippon Tetsuko Co., Ltd.)
0 parts by weight was spray coated and further heat treated at 200° C. for 5 hours to sinter, and then the aggregates were sieved to produce a carrier having a coating layer made of sintered silicone varnish. This is referred to as carrier CIJ. This carrier C1 is made of steel with an average grain size of 102μ.

(2) Carrier C2 In the production of carrier C1, silicone rubber l-51
In addition, 5 parts by weight of 1-2047J (manufactured by Le Silicone Co., Ltd.), 0.05 parts by weight of benzoyl peroxide, and too parts by weight of spherical copper-zinc 7-elite particles (Nippon Iron Powder Co., Ltd. 1) were used. was treated in the same manner to produce a carrier having a coating layer made of a sintered product of silicone rubber. This will be referred to as "Carrier C2." This CA97C2 has an average particle size of 81 μ-.

(3) Carrier C3 Silicone resin rSR-2400J (manufactured by Le Silicone Co., Ltd.) 2 parts by weight is dissolved in 50 parts by weight of xylene to coat the solution. After immersing 100B (manufactured by Kasei), it was heated to volatilize and remove the solvent xylene, further heat-treated at 200°C for 5 hours to sinter, and then the aggregates were sieved.
A carrier having a coated scrap made of sintered silicone resin was manufactured.

This is called "Carrier C3J. This carrier C3 is
The average particle size is approximately 60μ.

(4) Carrier C4 15 g of the above polymer was added to a mixed solvent of a7tone and methyl ethyl ketone (mixed volume ratio = 1:1) 500
1 lllL of the coating liquid was dissolved in mff1, and this coating liquid was coated on the magnetic particles 1 made of spherical copper-zinc particles using a fluidized bed apparatus, and further heated at 200°C. After heat treatment for 5 hours, the agglomerate was then sieved to produce a carrier with a coating layer.

This will be referred to as "Carrier C4".

This carrier C4 has an average particle size of 80μ.

(5) Carrier C5 styrene-methyl ethacrylate copolymer (monomer composition ratio = 30:70) 15 g/3 thyl ethyl ketone
00 mA' to prepare a coating solution, and using a [Spira Coater] (manufactured by Okayama Seiko Co., Ltd.), apply the above coating solution to 1 kg of spherical copper-zinc ferrite particles, and then heat and dry the coating solution. A carrier having layers was produced. This is called "Carrier C5J. This carrier C5 is
The average particle size is 110μ.

(Manufacture of non-magnetic toner) (1) Toner T1 100 parts by weight of poly-styrene-n-butyl acrylate copolymer (monomer composition ratio = 82718) and 10 parts by weight of carbon black [Mogul LJ (manufactured by Cabot Corporation)] and 2 parts by weight of "Nigrosine SO" (manufactured by Orient Kagaku Kogyo Co., Ltd.) were mixed in a V-type blender, then melted and kneaded with two rolls, cooled, coarsely ground with a hammer mill, and finely ground with a jet mill. The powder was pulverized and then classified using an air classifier to obtain a non-magnetic toner having an average particle size of 11.0 μm. This is referred to as [toner TIJ].

(2) Toner T2 In the production of toner T1, styrene-n-butyl acrylate methyl methacrylate copolymer (monomer composition ratio = 70:20:10) was used instead of styrene-n-butyl acrylate copolymer (monomer composition ratio = 70:20:10) 100 A nonmagnetic toner having an average particle size of 10.5 μm was obtained in the same manner except that parts by weight were used. This is referred to as "toner T 2 J."

(3) Toner T3 In the production of toner T1, styrene-n-butyl methacrylate copolymer (monomer composition ratio -65:35) was used instead of styrene-n-butyl acrylate copolymer.
In the same manner except that 100 overlapping parts were used, the average particle size was 1.
A non-magnetic l·ner of 1.3 μm was obtained. This is called "Toner T3J."

(Preparation of developer) A developer was prepared in the following manner using carrier, toner, silica fine particles, and zinc oxide in combinations and amounts shown in Table 2 below.

That is, first, silica fine particles are added to the toner, and
By mixing these with a Henschel mixer,
A developer of 11191 L is prepared by adhering fine silica particles to the surface of toner particles, and then adhering zinc oxide particles in the same manner, and then mixing these with a carrier.

(8+1 latent image bearing member) (1) Organic latent image bearing member P1 A photosensitive layer with a negatively charged two-chip structure formed using an anth 7thron pigment as a carrier-generating substance and a carbazole derivative as a carrier-transporting substance. were laminated on a rotating drum-shaped aluminum conductive support to construct an organic latent image carrier. This is referred to as an organic latent image carrier PIJ.

(2) Organic latent image carrier P2 An organic latent image carrier was constructed in the same manner as organic latent image carrier P1, except that a bisazo pigment was used as the carrier generating substance and a hydrazone derivative was used as the carrier transporting substance. This is referred to as [organic latent image carrier P2J].

(3) Organic latent image carrier P3 An organic latent image carrier was prepared in the same manner as organic latent image carrier P1 except that a bisazo pigment was used as a carrier generating substance and a styryl triarylamine derivative was used as a carrier transporting substance. Configured. This is referred to as [organic latent image carrier P3J].

Below/Margin A Live-action test> (1) Test 1 (Live-action test under room temperature environmental conditions) An organic latent image carrier for forming a negative charge latent image, a magnetic brush developer, and a corona that generates corona discharge. An electrophotographic copy RrU-B comprising a transfer device and a cleaning device having a cleaning blade made of urethane rubber.
Using a modified machine of ix1550MRJ (manufactured by Konishiroku Photo Industry Co., Ltd.), copies were made 150,000 times under room temperature environmental conditions of 20°C and 50% relative humidity, replacing the organic photosensitive layer image bearing after every 80,000 copies. A live photo test was conducted to form an image, and the following items were evaluated.

In each example and comparative example, the developer used was the f
It is as shown in the f12 table.

In addition, in the above-mentioned live-action test, other developing conditions were as follows. That is, the surface potential (highest potential) of the organic latent image carrier when it is charged is -500V, the magnet roll is a circular pin type, the magnetic flux density on the surface of the developing sleeve is 800 Gauss, and the direction of movement of the organic latent image carrier and the developing sleeve is are in the same direction, the ratio of the peripheral speed of the organic latent image carrier to the peripheral speed of the developing sleeve is 1:2, and the DC bias voltage applied to the developing sleeve is -150V.

The results are shown in Table 3 below.

(2) Fog The determination was made by measuring the relative density of a white background portion of the original with a density of 0.0 to the copied image using a "Sakura Densitometer" (manufactured by Konishi Roku Photo Industry Co., Ltd.). Note that the white background reflection density is 0.
．． It was set to 0. The evaluation is "O" if the relative concentration is less than 0°01, and if it is 0.01 or more and less than 0.03.
It was marked as "Δ", and cases of 0.03 or more were marked as "x".

(2) Image Density Using a "Sakura Densitometer" (manufactured by Konishiroku Photo Industry Co., Ltd.), the relative density of a white background portion with an original density of 0.0 was measured with respect to the copied image.

0 image quality copy image, image dropout, image disturbance, image sweeping, gradation,
Visual judgment was made from five viewpoints of sharpness. Evaluation,
A case where the test was good was marked as [O], but a case where it was slightly poor but at a practical level was marked as [Δ], and a case where it was poor and had a practical problem was marked as "x".

"Image dropout" refers to the phenomenon in which part of the image is missing, and "image disturbance" refers to the phenomenon of irregular shading differences in the entire image and toner adhering to the periphery of the image. "Eye" refers to the phenomenon in which a linear difference in shading appears in an image.

■Resolution In accordance with JIS Z 4916, equally spaced horizontal lines per 11 blades are 4.0, 5.0, 6.3, and 8.0.
Using the chart provided in this paper, we displayed the blades with discernible horizontal lines as resolution.

(2) Transfer rate After the transfer process, it was calculated by measuring the weight of the toner transferred to the transfer paper and the weight of the toner remaining on the organic latent image carrier.

■Toner scattering Visually observe the inside of the copying machine and the copied image. If the condition is good with almost no toner scattering, the rating is "O." If the toner scattering is slight but at a practical level, the rating is "Δ."
”, and cases where a large amount of toner scattering was observed and there was a problem in practical use were rated “×”.

■Cleanability After repeatedly forming an image, the surface of the organic latent image carrier was visually observed immediately after being cleaned with a cleaning blade, and the judgment was made based on the presence or absence of deposits on the surface of the organic latent image carrier. . The evaluation is 'OJ' when there are almost no deposits and is in good condition, 'Δ' when there are some deposits but at a practical level, and 'Δ' when there are many deposits and there are problems in practical use. was marked as "x".

(2) Test 2 (live-action test under high-temperature environmental conditions) A live-action test was conducted in the same manner as Test 1, except that the environmental conditions were high temperature, high humidity, and a temperature of 33°C and a relative humidity of 85%. Each item was evaluated. The results are shown in Table 4 below.

The following margins ゛,...) ,,' As can be understood from the results in Tables 3 and 4, according to the developer of the present invention, in the developing process, the organic latent image carrier is By fogging the negative charge latent image formed in , electrostatic transfer means allows for high transfer rates without image disturbance, gradation, or deterioration of resolution, and in the cleaning process, a cleaning blade with a simple structure allows for good cleaning. As a result, it is possible to form a clear image with high image density, good gradation, and resolution without fogging, image omission, image disturbance, image sweeping, or fringing phenomena.

Further, even when performing the image forming process many times, it is possible to stably form a good image.

In addition, good images can be stably formed many times even in high-temperature environments.

Although Examples 4 and 5 give relatively good results compared to the comparative example, the results are inferior in gradation and resolution among the examples, and the surface treatment of silica fine particles is Rather than amino-modified silane coupling agent and silicone oil, similarly amino-modified silicone oil,
This indicates that silicone rubber and silicone resin are preferred.

It is clear from the table that the comparative examples have many practical problems compared to the above examples.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example of an electrostatic image developing apparatus that can be suitably used to carry out development using the developer of the present invention. 10--Developed latent image carrier 10^--Conductive support 10B--Photosensitive l 11--Developing sleeve 12--Magnet roll 13-m-Regulated blade 17--Developer waste ( magnetic brush) 18-m-DC bias power supply

Claims (1)

[Claims] A negatively charged latent image developer containing a coated carrier, a nonmagnetic toner, positively charged silica particles, and zinc oxide powder.