JPH04149453A - Developer and image forming method - Google Patents

Abstract

PURPOSE:To prevent a fading phenomenon from occurring by containing binder resin which has polymerizable monomer units containing a carboxyl group or acid radical consisting of the acid anhydride of the carboxyl group by 2-30 pts. wt. of the entire quantity of resin and whose acid number of the entire resin is 1-70 in the developer. CONSTITUTION:A developing device provided with a developer carrier 2 for carrying and feeding the developer 5, which has a resin layer containing conductive fine grains or solid lubricant on its surface and whose depth Cv of cutting is Cv<5mum when relative load length tp=5% in the relative load curve (Abbot's load curve) of the surface, is used. In such a case, the developer 5 is incorporated with the binder resin which has the polymerizable monomer units containing the carboxyl group or the acid radical consisting of the acid anhydride of the carboxyl group by 2-30 pts. wt. of the entire quantity of the resin and whose acid number of the entire resin is 1-70. Thus, the fading phenomenon is prevented from occurring and a uniform image is expressed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a method for forming a latent image on an image bearing member such as an electrophotographic photoreceptor or an electrostatic recording dielectric material, and for making the latent image visible. The present invention relates to developers commonly used in developing devices or image forming methods using them.

[Prior Art] Conventionally, for example, a developing device that visualizes a latent image formed on the surface of a photosensitive drum as an electrostatic latent image carrier using magnetic toner as a one-component developer has been developed by The electrostatic image charge and the development reference potential formed on the photosensitive drum due to friction and the friction between the sleeve as a developer carrier and the magnetic toner particles are applied with a charge of opposite polarity to the magnetic toner particles. The toner is coated very thinly on the sleeve and conveyed to the developing area formed by the photosensitive drum and the sleeve. In the developing area, the magnetic field from the magnet fixed inside the sleeve causes the magnetic toner to fly and absorb the electrostatic latent on the photosensitive drum. There are known devices that visualize images.

However, in the conventional example described above, there is a problem in that when the same image pattern is repeatedly printed, portions with low density occur in a twill pattern. FIG. 4 shows a schematic diagram of the image.

This is a phenomenon in which characters become thinner in character images, and density becomes lower in halftone and solid black images. This phenomenon will be referred to as fading hereinafter.

Further, the above-mentioned fading phenomenon is particularly noticeable in high-temperature environments where the charge of the developer tends to decrease, and a solution to this problem has been awaited.

[Problems to be Solved by the Invention] An object of the present invention is to provide a developer that solves the above-mentioned drawbacks or an image forming method using the same.

That is, an object of the present invention is to provide a developer capable of preventing the so-called fading phenomenon and displaying a uniform image, or an image forming method using the developer.

In particular, an object of the present invention is to provide a developer capable of preventing the occurrence of fading in a high-temperature environment and displaying a uniform image, or an image forming method using the developer.

[Means for Solving the Problems] That is, an object of the present invention is to have a resin layer containing at least conductive fine particles or a solid lubricant on its surface, and to have a resin layer containing at least conductive fine particles or a solid lubricant, and to A developer applied to an image forming method using a developing device having a developer carrier for supporting and transporting the developer, in which the cutting depth Cv is Cv <5 μm when the load length tp = 5%. The developer has 2 to 30 parts by weight of a polymerizable 1,000-mer unit containing an acid group consisting of a carboxyl group or an acid anhydride thereof based on the total amount of the resin, and the acid value of the entire resin is 1 to 70. This is achieved using a developer and an image forming method characterized by containing a certain binder resin.

Hereinafter, a developing device used in the present invention will be explained based on the accompanying drawings.

FIG. 1 is a sectional view of an example of a developing device used in the present invention.

1 in the figure is a photosensitive drum as a static image carrier that carries an electrostatic latent image and rotates in the direction of arrow A. Of course, it can be used with or without an insulating layer on the surface. It is not limited to a drum shape, but also a sheet shape or a belt shape.

Reference numeral 2 denotes a sleeve as a developer carrier that carries toner 5 on its surface and rotates in the direction of arrow B. A multipolar permanent magnet 3 is fixed inside the sleeve 2 so as not to rotate. Further, on the surface of the sleeve 2, a coating layer 10 containing conductive fine particles, which will be described later, is formed to a thickness of approximately 0.5 μm to 30 μm. Reference numeral 4 denotes a developer storage chamber that stores the toner 5 and brings the toner 5 into contact with the surface of the sleeve 2 . Reference numeral 6 denotes a doctor blade as a member that regulates the layer of toner 5 on the surface of the sleeve 2 carried in the developer storage chamber 4 to a predetermined thickness, and the gap between the surface of the sleeve 2 and the doctor blade 6 is about 50 μm. ~500 μm.

The developing device configured as described above starts and the sleeve 2
When the toner rotates in the direction of arrow B, the electrostatic latent on the photosensitive drum 1 changes in relation to the reference potential for development due to contact friction between the toners 5 or between the toner 5 and the surface of the sleeve 2 in the developer storage chamber 4. A charge having a polarity opposite to that of the image is given to the toner 5 and applied to the surface of the sleeve 2. The toner layer applied to the sleeve surface is further coated into a uniform and thin layer (layer thickness is approximately 30 μm) by a doctor blade 6 disposed opposite to one magnetic pole (S pole in the figure) of the multipolar permanent magnet 3. ~300μm)
The photosensitive drum 1 and the sleeve 2 form a developing area.

Furthermore, by applying an AC bias between the sleeve 2 and the surface of the photosensitive drum 1 in the development area, the toner 5 on the sleeve 2 may be caused to fly toward the photosensitive drum.

Here, the coating layer 10 formed on the sleeve surface will be explained.

The coating 10 used is one in which the coating layer-forming polymer material contains conductive fine particles.

As the conductive fine particles, carbon fine particles, carbon fine particles and crystalline graphite, or crystalline graphite are preferable.

The crystalline graphite used in the present invention can be roughly divided into natural graphite and artificial graphite. Artificial graphite is made by hardening pitch coke with tar pitch, etc., firing it once at about 1200℃, then putting it into a graphitization furnace and treating it at a high temperature of about 2300℃, which causes carbon crystals to grow and turn into graphite. do. Natural graphite is produced from underground after being completely graphitized by natural geothermal heat and high underground pressure over a long period of time. These graphites have various excellent properties and have a wide range of industrial uses. Graphite is
A very soft and slippery crystalline mineral with a dark gray or black luster. It is used in pencils, etc., and is heat resistant and chemically stable, so it is used as powder, solid, and paint for lubricants, fire resistance, electrical materials, etc. It is used in the form of The crystal structure includes hexagonal crystals and rhombohedral crystal structures, and has a completely layered structure. Regarding electrical properties, free electrons exist between carbon and carbon bonds, making it a good conductor of electricity. Note that the graphite used in the present invention may be either natural or artificial.

Furthermore, the graphite used in the present invention has a particle size of 0.5 μm.
~10 μm is preferred.

Examples of film-forming polymeric materials include thermoplastic resins such as styrene resins, vinyl resins, polyethersulfone resins, polycarbonate resins, polyphenylene oxide resins, polyamide resins, fluororesins, cellulose resins, and acrylic resins, and epoxy resins. Thermosetting resins or photocurable resins such as resins, polyester resins, alkyd resins, phenol resins, melamine resins, polyurethane resins, urea resins, silicone resins, and polyimide resins can be used. Among them, materials with mold release properties such as silicone resin and fluororesin, or polyether sulfone, polycarbonate, polyphenylene oxide, polyamide,
More preferred are materials with excellent mechanical properties such as phenol, polyester, polyurethane, and styrene resin.

Conductive amorphous carbon is defined numerically as "an aggregate of crystallites formed by the combustion or pyrolysis of hydrocarbons or carbon-containing compounds in the presence of insufficient air supply." In particular, it has excellent electrical conductivity, and is widely used because it can be filled into polymeric materials to impart electrical conductivity, and it is possible to obtain a desired electrical conductivity to some extent by controlling the amount added. The particle diameter of the conductive amorphous carbon used in the present invention is preferably 10 μm to 80 μm, more preferably 15 μm to 40 μm.

Next, the fading phenomenon, which is a problem to be solved by the present invention, will be explained. If you observe the sleeve when this phenomenon occurs, you will find that the toner layer is uniformly formed, which is a different phenomenon from white spots due to toner exhaustion or the like. When we measured the amount of charge on the toner on the sleeve (hereinafter referred to as "tribo"), we found that it was a lower value than normal.

In other words, in addition to toner that has been normally charged at 18:t, toner that is not sufficiently charged passes through the concentrated magnetic field formed by the blade 6 and magnet 3 in FIG. 1 due to the frictional force received from the sleeve surface, and forms a toner layer on the sleeve. Form. This reduces the triboelectricity of the toner layer,
This phenomenon occurs because the image is not developed on the drum even if it receives alternating electric fields between the drum and the sleeve. In order to prevent this, it is necessary to increase the triboelectricity of the toner layer. That is, when the toner passes through the concentrated magnetic field formed by the magnetic blade 6 and the magnet 3, the toner passes through the concentrated magnetic field only due to the reflection force acting between the toner and the sleeve, not due to the frictional force received from the sleeve surface. By doing so, it is possible to form a toner layer using only toner having a normal trigonometric force with a large mirroring force, and this problem can be avoided.

In order to reduce the friction on the sleeve surface and increase the slipperiness, the center line average roughness Ra(
Merely reducing the value of Ra (hereinafter abbreviated as Ra) cannot be expected to produce a reliable effect; rather, reducing Ra causes problems such as an insufficient amount of toner coating on the sleeve.

The sleeve of the present invention can be produced, for example, by spraying a prepared solution as shown in the following formulation onto the surface of a drawn aluminum tube (surface viscosity 2S) to a thickness of approximately 0.5 to 30 μm.
The coating treatment can be carried out by coating to a certain extent and then thermally curing in a drying oven (150° C.).

(Formulation example 1) Resin: Phenol resin (solid content) 30Ji
Part carbon・C0NDUCTEX 975 UB (
(manufactured by Columbia Carbon) 25 parts by weight Diluent: 200 parts by weight of methyl alcohol methyl cellosolve (formulation example 2) Resin: 15 parts by weight of phenolic resin (solid content) Conductive lubricant: Artificial Graphite (1 μm) 15 parts by weight Diluent... Methyl alcohol Methyl cellosolve 225 parts by weight or more Sleeves are manufactured through a process such as the following, but with only the above process, cutting when relative load length tP = 5% It is difficult to reduce the depth Cv to 5 μm or less, and for this purpose, it is effective to add surface polishing to the sleeve at the end.

For example, a surface polished with felt can be used. This polishing process will be briefly explained using an example.

After the drying process, the sleeve is rotated at about 800 rpm and brought into contact with felt under a pressure of about 1 to 3 kg. 1 to 5 cm/s in the longitudinal direction of the sleeve.
Polishing is completed by moving it from one end to the other at a speed of ec. The polishing method is not limited to this (, cloth,
This can be done with a rag or the like, or it can be done directly by hand without rotating the sleeve.

The sleeve of the present invention is produced as described above.

Here, let us consider the reason why the Cv value when tp = 5% is related to the occurrence rate of fading, and why Ra cannot be unconditionally related to the occurrence rate of fading. Figure 2(a)
, (b) are schematic diagrams showing the surface profiles of two types of sleeves, A and B.
Cv value (hereinafter Cv
Table 1 shows an example of the relationship between Ra, sleeve surface slipperiness, and fading.

Table 1 Sleeve A has a Cvs of 10 μm and a Ra of 2.5 μm, and a sleeve B has a Cvs of 1.0 μm and a Ra of 2.0 μm by applying surface polishing and pressure to the sleeve A. The value of Cv changed greatly from 10 to 1 and Oam, but the Ra did not change much from 2,5 to 2 and Oam.

The difference in B is obvious when looking at the profile shown in Figure 's2. In case A, the unevenness of the profile is sharp and the roughness is large, so both CVS and Ra take large values, but in case B, the convex portions of the profile are rounded by surface polishing, so CVS takes a small value. However, since the recess remains as it is, Ra remains at a relatively large value. As for fading, sample A had sharp unevenness and poor slipperiness on the sleeve surface, causing fading. In case B, since the convex portions were rounded, the sleeve surface had good slipperiness and no fading occurred.

It has been found that by defining the CVS value of the sleeve surface as described above, it is possible to improve the slipperiness of the sleeve surface and prevent the occurrence of fading.

Next, the relative load curve on the sleeve surface, which is a feature of the present invention, will be explained.

Figure 's3 shows the profile (cross-sectional curve) of the sleeve surface per reference length and the corresponding relative load curve (Abbott's load curve). A relative load curve is a certain level in the profile per standard length that is parallel to the average line of this standard length section (the distance from the highest peak of the standard length section to this level is called the cutting depth Cv).
When the standard length section is cut with a straight line, the ratio of the line segment length of the cut 11 +It2+...+Jln and the standard length is the relative load length at that level (cutting depth) It is called tP, and a relative load curve is a graph of the relationship between the cutting depth and the relative load length. (In this example, the surface roughness measuring instrument S E-30H
(manufactured by Kosaka Laboratory Ltd.) In the present invention, the occurrence of fading is prevented by focusing on the cutting depth Cv when the relative load length tP = 5% in this relative load curve and setting Cv < 5 μm. It was designed to do so.

As described above, by setting the CVS value to Cvs<5 μm, fading can be prevented from occurring. Furthermore, in order to make the CVS value Cvs<5 μm, it is effective to polish the sleeve surface.

As mentioned above, Ra is not a reliable means of suppressing the occurrence of fading, but if Ra<0.4μ
In the case of m, there are disadvantages such as a low image density due to an insufficient amount of toner coating on the sleeve and uneven coating of the developer due to non-uniform charging of the developer. Therefore, the value of Ra is
It is necessary that Ra≧0.4 μm, preferably Ra>0.5 μm.

It is also possible to blast the surface of the sleeve coating film after drying in order to reduce the CVS value of the sleeve surface to 5 μm or less. , Alundum #400, or other abrasive grains. Further, in order to remove the coating film fine powder ground by the blasting process, alcohol cleaning or the like can also be performed together.

Next, the developer according to the present invention will be explained.

The developer of the present invention contains as an essential component a resin having a polymerizable monomer unit containing an acid group consisting of a carboxyl group or its acid anhydride.

By having the above-mentioned structure, the developer according to the present invention can prevent the fading phenomenon, especially under high temperature conditions, and can fully utilize the original performance of the coat sleeve according to the present invention. . That is, the developer according to the present invention is
Matches extremely well with the image forming apparatus according to the present invention,
This is a developer that allows the image forming apparatus to be fully utilized, and by using the developer and image forming apparatus according to the present invention, an image forming method that provides good images has been established.

The reason for this is that by using a resin having a polymerizable monomer unit containing an acid group consisting of a carboxyl group or an acid anhydride thereof, the developer has a remarkable triboelectric charging uniformity effect. In other words, it meets the requirements for a sleeve that has the ability to increase the contact zone due to developer slippage, and has a uniform property even in high-temperature environments. We believe that this is because it has become possible to form a charged developer layer.

Various resins can be used as the binder resin having acid groups according to the present invention, and examples of polymerizable resins containing acid groups include the following.

α, β-unsaturated carboxylic acids such as acrylic acid, methacrylic acid; α, β-unsaturated carboxylic acids such as maleic acid, butyl maleate, octyl maleate, fumaric acid, butyl fumarate
-Unsaturated dicarboxylic acids.

or half esters thereof; n-butenylsuccinic acid, n
-otatenylsuccinic acid, butyl n-butenylsuccinate,
Examples include alkenyldicarboxylic acids such as n-butenylmalonic acid and n-butenyladipic acid, and half esters thereof. Preferred are anhydrizable dicarboxylic acids and derivatives thereof.

In this case, the amount of polymerizable mercury containing acid groups is preferably 2 to 30 parts by weight based on the total amount of the binder resin, and the acid value of the entire binder resin is 1 to 70, more preferably 5 to 50. good.

The method for measuring acid value used in the present invention is shown below.

Acid value is JIS K-0670 &:! 1! Measure accordingly.

That is, 2 to 10 g of a sample is weighed into a 200 to 300 mJl Erlenmeyer flask, and a mixed solvent of ethanol:benzene = 1:2 is added at about 50 mC to dissolve the resin. If the solubility is poor, a small amount of acetone may be added. Using a phenolphthalein indicator, titration is performed with a pre-standardized N/10 potassium-ethanol solution, and the acid value is determined from the consumption amount of alcoholic potassium solution using the following formula (3).

Acid value = KOH (mu number) x N x 56.1/sample weight... (3
) (N is a factor of N/10 KO) f) Examples of comonomers for obtaining the binder resin according to the present invention include the following.

For example, styrene, 0-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene,
p-phenylstyrene, p-chlorostyrene, 3.4-
Dichlorostyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-n-butylstyrene, p-tert
-butylstyrene, p-n-hexylstyrene, p-n
-octylstyrene, p-n-nonylstyrene, p-n
- Styrene and its gluten conductors such as decylstyrene and p-n-dodecylstyrene; ethylenically unsaturated monoolefins such as ethylene, propylene, butylene and isobutylene; unsaturated polyenes such as butadiene; vinyl chloride,
Vinyl halides such as vinylidene chloride, vinyl bromide, vinyl fluoride; vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate; methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate , isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, etc.
Methylene aliphatic monocarboxylic acid esters; methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate/n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate , acrylic acid 2-
Acrylic acid esters such as chloroethyl and phenyl acrylate; Vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, and vinyl isobutyl ether; Vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, and methyl isopropenyl ketone: N-vinyl pyrrole, N - N-vinyl compounds such as vinylcarbazole, N-vinylindole, and N-vinylpyrrolidone; vinylnaphthalenes: acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, and acrylamide; single or two vinyl monomers Used above.

Among these, combinations of styrene-based copolymers and styrene-acrylic copolymers are preferred.

The vinyl copolymer used in the present invention is preferably a polymer crosslinked with a crosslinkable monomer as exemplified below.

Aromatic divinyl compounds, such as divinylbenzene, divinylnaphthalene, etc.; diacrylate compounds linked with alkyl group, such as ethylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1
．． 4-butanediol diacrylate, 1.5-bentanediol diacrylate, 1.6-hexanediol diacrylate, neopentyl glycol diacrylate, and the above compounds in which the acrylate is replaced with methacrylate; alkyl containing an ether bond Chained diacrylate compounds, such as diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate,
Polyethylene glycol #400 diacrylate, polyethylene glycol #600 diacrylate, dipropylene glycol diacrylate, and the above compounds in which the acrylate is replaced with methacrylate; diacrylate compounds linked by groups containing an aromatic group and an ether bond such as polyoxyethylene (2)-2,2-
Bis(4-hydroxyphenyl)propane diacrylate, polyoxyethylene(4)-2,2-bis(4-hydroxyphenyl)propane diacrylate, and the above compounds in which the acrylate is replaced with methacrylate; Examples include polyester-type diacrylate compounds, such as the trade name MANDA (Nippon Kayaku). Examples of polyfunctional crosslinking agents include pentaerythritol triacrylate, trimethylolethane triacrylate, trimethylolpropane triacrylate, tetramethylolmethanetetraacrylate, oligoester acrylate, and nitriarylic compounds obtained by replacing the acrylate of the above compounds with methacrylate. Lucianurate,
Triallyl trimellitate: etc.

It is preferable to use these crosslinking agents in an amount of about 0.01 to 5 parts (more preferably about 0.03 to 3 parts) per 100 parts of other components.

Among these crosslinking compounds, aromatic divinyl compounds (particularly divinylbenzene),
Mention may be made of bound diacrylate compounds containing aromatic groups and ether linkages.

As a method for synthesizing the binder resin according to the present invention, it is also possible to basically use a method of synthesizing two or more types of polymers.

That is, it is a method in which a first polymer that is soluble in THF and soluble in a polymerization monomer is dissolved in a polymerization monomer, and the monomer is polymerized to obtain a resin composition. In this case, a composition is formed in which the former and latter polymers are uniformly mixed.

The first polymer soluble in THF is preferably subjected to solution polymerization or ionic polymerization, and the second polymer for producing a component insoluble in THF is prepared under the conditions in which the first polymer is dissolved. It is preferable to synthesize by suspension polymerization or bulk polymerization in the presence of a crosslinking monomer. It is preferable to use 10 to 120 (preferably 20 to 100 parts by weight) parts by weight of the first polymer based on 100 parts by weight of the polymerizable monomer for producing the second polymer.

Solvents used in solution polymerization include xylene, toluene,
Cumene, cellosolve acetate, isopropyl alcohol, benzene, etc. are used. In the case of styrene monomers, xylene, toluene or cumene are preferred. It is appropriately selected depending on the polymer to be polymerized. Further, the initiator includes di-tert-butyl peroxide, tert-butyl peroxybenzoate, benzoyl peroxide, 2.
2°-azobisisobutyronitrile, 2°2'-azobis(2,4 dimethylvaleronitrile), etc.
0 parts by weight, or more than 0 parts by weight, or 0.
(4 to 15 parts by weight). The reaction temperature varies depending on the solvent, initiator, and polymer to be polymerized, but it is preferably carried out at 70°C to 180°C. In solution polymerization, 30 parts by weight per 100 parts by weight of solvent.
It is preferable to use 400 parts by weight to 400 parts by weight.

It should be noted that when solution polymerization is carried out using α, β-unsaturated dicarboxylic acids or half esters thereof, it has been found that cyclization due to anhydration occurs to some extent when the temperature is raised after the reaction is completed and the reaction solvent is evaporated. This was also confirmed by IR in the present invention.

According to the studies conducted by the present inventors, dicarboxylic acids are more preferable than monocarboxylic acids in terms of charging stability when comparing the acid groups contained in the developer at the same acid value.

Further, as the coloring material that can be roughly added to the developer according to the present invention, conventionally known carbon black, copper phthalocyanine, iron black, etc. can be used.

As the magnetic fine particles contained in the magnetic toner according to the present invention, a substance that is magnetized when placed in a magnetic field is used, such as powder of a ferromagnetic metal such as iron, cobalt, or nickel, or magnetite.

Alloys and compounds such as γ-Fez Os and ferrite can be used.

These magnetic fine particles preferably have a BET specific surface area of 1 to 20 m"/g, particularly 2.5 to 12 m" by nitrogen adsorption method.
/g, and preferably a magnetic powder having a Mohs hardness of 5 to 7.

The content of this magnetic powder is preferably 10 to 70% by weight based on the weight of the developer.

Further, the toner of the present invention may contain a charge control agent if necessary, such as metal complex salts of monoazo dyes, salicylic acid,
A negative charge control agent such as a metal complex salt of alkyl salicylic acid, dialkyl salicylic acid or naphthoic acid is used.

The developer of the present invention may further include other additives, such as Teflon, lubricants such as zinc stearate, fixing aids (such as low molecular weight polyethylene), or conductivity imparting agents, as long as they do not have a substantial adverse effect. Alternatively, a metal oxide such as tin oxide may be added.

In producing the developer of the present invention, the constituent materials are thoroughly kneaded using a heat kneader such as a hot roll, kneader, or extruder, and then obtained by mechanical crushing or classification, or the materials are mixed in a binder resin solution. After dispersing 91N
There are various methods for producing toner, such as drying, or polymerization toner production by mixing monomers to form the binder resin with a specified material to form an emulsified suspension, and then polymerizing the resulting toner. It can be applied.

The basic configuration and features of the present invention have been described above, and the method of the present invention will be specifically explained below based on Examples. However, this does not limit the embodiments of the present invention in any way. Parts in the examples are parts by weight.

[Example] 200 parts of cumene was placed in a one-wheel reactor, and the temperature was raised to reflux temperature. To this were added 85 parts of styrene monomer, 15 parts of acrylic acid monomer and 8.5 parts of di-tert-butyl peroxide.
parts were mixed. Roughly cumene under reflux (146℃~156℃
The solution polymerization was completed at 10°C (°C) and the cumene was removed by increasing the temperature.

The obtained styrene-acrylic acid copolymer is soluble in THF, Mw=3,500, Mw/Mn=2.52, G
The molecular weight where the main beak of PC is located is 3.300, T
g=56°C.

30 parts of the above copolymer was dissolved in the following monomer mixture to prepare a mixed solution.

Add 0% of the partially saponified polyvinyl alcohol to the above mixed solution.
170 parts of water in which 1 part was dissolved was added to form a suspension dispersion. The above suspension dispersion was added to a reactor containing 15 parts of water and purged with nitrogen, and the suspension polymerization reaction was carried out for 6 hours at a reaction temperature of 70 to 95°C. After the completion of the reaction, it was filtered, dehydrated, dried, and copolymerized. A combined composition was obtained. In the composition, a styrene-acrylic acid copolymer and a styrene-acrylic acid-n-butyl acrylate copolymer were uniformly mixed. THF of the obtained resin composition
When the molecular weight distribution of the soluble component was measured, in the GPC chart, there were peaks at approximately 35,000 and 31,000 positions, Mn = 0,510,000, Mw = 115,000, and M w
/ M n =22.5, molecular weight of 10,000 or less is 27 wt%
Met. Furthermore, the Tg of the resin is 59°C, and the GPC
Glass transition point Tg+ of 10,000 or less components separated by
The temperature was 57°C.

Further, the acid value of this copolymer was 22.0.

1 skin (M2 200 parts of cumene was placed in a reactor and the temperature was raised to reflux temperature.

To this, 78 parts of styrene monomer, 15 parts of n-butyl acrylate monomer, and 7 parts of n-butyl maleate half ester.
A mixture of 1.0 parts of divinylbenzene, 0.3 parts of divinylbenzene, and 1.0 parts of di-tert-butyl peroxide was added dropwise over 4 hours under cumene reflux, the polymerization reaction was carried out for 4 hours, and then the solvent was removed by ordinary vacuum distillation. was removed to obtain a copolymer. The obtained copolymer had Mw=350,000, Mw/Mn=11
．． 0, Tg=60°C.

Further, the acid value of this copolymer was 18.5.

200 parts of cumene was placed in a Nen JJ discharge reactor, and the temperature was raised to reflux temperature. The following mixture was subjected to solution polymerization under reflux of cumene, and after the reaction was completed, the temperature was raised to remove cumene.

The obtained copolymer had Mw=6900, Mw/Mn=2
．． 36, has a main beak at a molecular weight of 7200,
Tg=64°C.

30 parts of the above styrene-n-butyl maleate half ester copolymer was dissolved in the following monomer mixture to form a mixture, and the same procedure as in Synthesis Example 1 was carried out to obtain a mixture of styrene-n-butyl maleate half ester copolymer and A composition of styrene-n-butyl acrylate-n-butyl maleate half ester copolymer was obtained.

The acid value of this copolymer was 20.6.

11■1 The same procedure as Synthesis Example 3 was carried out except that 82 parts of the styrene monomer and 3 parts of n-butyl maleate half ester were used.

The acid value of the obtained copolymer was 7.3.

The above mixture is melt-kneaded with a twin-screw extruder heated to 140°C, the cooled kneaded product is coarsely pulverized with a hammer mill, the coarsely pulverized material is pulverized with a jet mill, and the resulting finely pulverized powder is air-classified. A magnetic particle classified powder with a volume average particle diameter of 12 μm was obtained, 0.6 parts of hydrophobic colloidal silica fine powder was added to 100 parts of the above magnetic particles, and the mixture was mixed in a Henschel mixer to obtain developer (I). Ta.

The above mixture was mixed with magnetic particle classified powder (
II) was obtained, and in the same manner as in Production Example 1, hydrophobic colloidal powder was added and mixed in a Henschel mixer to obtain a developer (
II) was obtained.

11 Gorei-1 Magnetic particles were obtained in the same manner as in Production Example 1, except that the resin composition in Production Example 3.4 was used instead of the resin composition in Synthesis Example 1, and hydrophobic particles were obtained in the same manner as in Example 1. Fine silica powder was added and mixed to obtain developers (III, IV).

Husband 1 Medical 2j A commercially available laser beam printer LBP-3X (manufactured by Canon) was modified, and the surface of the developer carrier was prepared according to the method described above according to Formulation Example 2, that is, conductive graphite particles were mixed with phenol resin at a ratio of 1:1. A film was coated with a synthetic resin containing a proportion of 7.5 μm (thickness: 7.5 μm), and the surface was polished by bringing felt into contact with it as described above. This was used as an evaluation device for image output. The developing bias was an AC bias VP of 1600 V and a frequency of 1800 Hz, and the distance between the developer carrier of the present invention and the photosensitive drum serving as the electrostatic latent image carrier was approximately 300 microns.

Next, using the developers of Production Examples 1 to 2 in the above-mentioned evaluation machine, a real photo test was conducted at room temperature (25 DEG C., 60% Rh), high temperature and high humidity, and the printout images were evaluated.

Table 2 shows the Ra, Cvs values, and image evaluation results of the developer carrier.

Fading evaluation ○...Fade does not occur at all.

O△: Slight fading occurs, but there is no practical problem.

△　・・・Weak fading, but practically impossible.

×: Fading occurs and white spots appear in the image.

[Effect of the invention] As described above, at least conductive fine particles or
It has a resin layer containing a solid lubricant on its surface, and in the relative load curve (Abbott's load curve) of the surface, the cutting depth Cv when the relative load length tP = 5% is C
By using the developer according to the present invention in an image forming method using a developing device having a developer carrier for supporting and transporting developer where v≦5 μm, the occurrence of so-called fading phenomenon can be prevented at room temperature. It is now possible to prevent this not only at room temperature but also at high temperature and high humidity.

[Brief explanation of the drawing]

Fig. 1 is a schematic sectional view of the developing device used in the present invention, Fig. 2 is a schematic cross-sectional view of the developing device used in the present invention;
Figures (a) and (b) are schematic diagrams showing the surface profiles of two types of sleeves, A and B. Figure 3 is an explanatory diagram of the relative load curve, and Figure N4 is an explanatory diagram of the fading phenomenon. 1... Electrostatic latent image carrier (rIA optical drum) 2... Developer carrier (sleeve) 3... Multipolar permanent magnet 4... Developer storage chamber 6... Doctor blade 10.・・Coating layer

Claims (2)

[Claims] (1) It has a resin layer containing at least conductive fine particles or a solid lubricant on its surface, and has a relative load length t_P in the relative load curve (Abbott's load curve) of the surface.
= 5%, cutting depth C_V is C_V≦5μ
m, which is applied to an image forming method using a developing device having a developer carrier for supporting and transporting the developer, wherein the developer is composed of a carboxyl group or an acid anhydride thereof. 2 to 30 parts by weight of the total amount of the resin contains polymerizable monomer units containing acid groups, and the acid value of the entire resin is 1.
A developer characterized by containing a binder resin having a molecular weight of 70 to 70. (2) It has a resin layer containing at least conductive fine particles or a solid lubricant on its surface, and has a relative load length t_P in the relative load curve (Abbott's load curve) of the surface.
= 5%, cutting depth C_V is C_V<5μ
m, in which the developer is a polymerizable monomer containing an acid group consisting of a carboxyl group or an acid anhydride thereof; The unit is 2 to 3 of the total amount of resin.
1. An image forming method comprising: a binder resin having an acid value of 0 parts by weight and an acid value of the entire resin from 1 to 70.