JPH02210366A - Developer and its production - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a developer mainly used in electrophotography,
In particular, the present invention relates to an improved developer containing a carrier and a method for producing the same.

[Prior art and problems to be solved by the invention] Conventionally,
Carriers in which iron powder, glass powder, etc. are coated with resin are disclosed in JP-A No. 47-17434, JP-A No. 47-13954, and JP-A No. 5.
As disclosed in No. 6-13946, by attaching toner powder to the surface of a carrier, it is possible to prevent spent from impairing its durability, and to improve the charging property imparted to the toner powder. was its main purpose.

However, when using resin-coated magnetic carrier with toner,
When an electrostatic latent image is developed by being carried on a rotating developing sleeve, there is a problem that when the toner separates from the carrier, it separates to areas other than the electrostatic latent image and the toner scatters and is emitted outside the developing area.

In order to prevent this, it is possible to increase the chargeability of the carrier coating resin and increase the electrostatic adhesion of the carrier itself to the toner, but in this case.

Particularly under low humidity, carrier charge-up (a rapid increase in the amount of charge) is likely to occur, and toner strongly electrostatically adheres to the carrier, causing deterioration of development characteristics.As a result, image density decreases and undesirable I/O Notebook.

Incidentally, the following proposal has been made in an attempt to improve this by mixing fine powder such as a pigment into the resin of the resin-coated carrier.

JP-A-53-100242 discloses that in the carrier coating resin,
By containing nigrosine, the negative chargeability of the toner is improved and peeling of the resin film and electrostatic aggregation are prevented.

JP-A-56-75659 discloses that porous carbon black is contained in a carrier coating resin.

The purpose is to increase the electrical conductivity of the resin-coated carrier and increase the durability of the carrier.

JP-A-60-57362 is in a carrier coating resin.

The purpose is to prevent the edge phenomenon by containing conductive magnetic fine powder treated with a coupling agent.

Furthermore, JP-A-60-73631 discloses a silicone resin-coated carrier containing an inorganic filler and a silane coupling agent in the resin to improve the strength of the resin coating.

However, dispersing fine powder such as pigment in resin has limitations due to the compatibility and dispersibility of the resin and fine powder, and it is not possible for all resins and all fine powder to be well dispersed. Therefore, when a fine powder is combined with a resin that has poor compatibility with the powder, poor dispersion tends to occur, and as a result, the charging properties imparted to the toner become uneven, resulting in fogging, etc. Image defects and spent images are more likely to occur.

This tends to occur when the amount of FM fat coating is small, specifically when the amount of resin to the carrier is 0.1 to 5% by weight, and in extreme cases, the carrier powder and fine powder coated only with resin are dispersed. There are even cases where the powder is mixed with resin-coated carrier powder.

The present invention provides a developer and a method for producing the same which eliminates the above-mentioned drawbacks.

That is, the purpose of the present invention is to eliminate some of the causes of poor images, such as carrier charge-up under low humidity, internal contamination due to toner scattering, and scratches caused by carrier adhesion on the photoreceptor. The present invention provides a developer containing a novel resin-coated carrier that solves in-machine contamination caused by toner scattering, and a method for manufacturing the same.

[Means to solve the problem]

The present invention provides a developer comprising at least carrier particles having fine powder particles such as a pigment held on a carrier surface coated with a resin, and toner particles,
The triboelectrification series is toner particles>carrier particles>fine powder particles or.

Toner particles (carrier particles) A developer characterized by being fine powder particles, and the method for producing the developer includes fine powder such as pigment having a particle size ratio of 0.2 or less to the resin-coated carrier. The particles are passed through an impact section in which the shortest gap between a rotating piece and a fixed piece or between two types of rotating pieces is 0.5 to 71 mm under an ambient temperature of 10 to 100°C,
Obtain carrier particles with the fine powder held on the surface of the carrier, mix the carrier particles with at least toner particles, and triboelectrically charge the toner particles>carrier particles>fine powder particles or the like.

This is a method for producing a developer characterized in that toner particles (carrier particles) are made into fine powder particles.

The developer configured according to the present invention does not cause internal contamination due to toner scattering.

Furthermore, JP-A No. 61-9661 proposes a microcarrier in which a fluidity improver is added to a magnetic powder-dispersed carrier. The carrier particles of the present invention are completely new, since the carrier particles of the present invention are those in which a property improver is added and stirred, and fine particles are attached thereto as in the present invention.

In the present invention, holding fine powder particles (hereinafter referred to as particles A) on the surface of a resin-coated carrier means that impact energy (mechanical and thermal energy) to mechanically bond a part of the particles A to the resin on the surface of the carrier that has been melted or softened by the aS energy, and cooled and fixed in this state, and the shape of the particles A is It does not need to be held as is on the carrier, nor does it need to be completely buried.

The shape of the carrier may be spherical or other regular shapes, but the particles A are preferably uniformly attached to the surface of the carrier, and the particle size of the particles A is equal to the particle size of the carrier 1.
0.2 or less is preferable. Note that the above structure can be observed using an electron microscope.

Each particle constituting the present invention will be explained below.

In addition to magnetic materials such as iron powder, oxidized iron powder, ferrite, and nickel, examples of the 1 Yaria core material that can be used in the developer of the present invention include glass beads, silica particles, sodium chloride, ammonium chloride, and Rochelle salt. etc. can be used. The particle size of the core material is approximately 20 to 500 .mu.m, preferably 30 to 300 .mu.m.

Coating resins include silicone resin, fluorine resin,
Styrenic resin 2 Acrylic resin, styrene-acrylic resin, polyvinyl acetate, cellulose derivative, maleic acid resin, epoxy resin.

Polyvinyl chloride, polyvinylidene chloride, polyvinyl bromide, polyvinylidene bromide 2 polycarbonate, polyester, polyethylene, polypropylene, phenolic resin,
PVA, fumaric acid ester resin, polyacrylonitrile, polyvinyl ether, chloroprene rubber, acetal resin, ketone resin, xylene resin, butadiene rubber, styrene-butadiene copolymer, etc. can be used. The thickness of the resin coating on the carrier core material is preferably about 0.1 to 3μ, and the amount of resin in the carrier is 0.1 to 20% by weight. Particularly, the effect of the present application is 0.1 to 5% by weight. This effect is exhibited when the coating is fairly thin.

The fine powder particles (particles A) used include metal oxides such as hydrophilic silica, hydrophobic silica, cerium oxide, alumina, zirconia, silicon carbide, boron carbide, clay, talc, and magnesium oxide. , nigrosine, quaternary ammonium salts, triphenylmethane dyes, metal monoazo dyes and pigments, and other charge control agents can also be used. Among these, high-resistance fine powder is particularly preferable because it reduces fluctuations in development characteristics due to environmental humidity changes.High resistance here refers to the volume when the powder is compressed into a tablet and IOV is applied. The content of the particles A, which means that the resistance is 10'Ωc or more, is preferably 0.5 to 50 parts by weight, particularly 1 to 30 parts by weight, based on 100 parts by weight of the coating resin. If it exceeds 50 parts by weight.

There is a tendency for charge-up under low humidity conditions, which is undesirable.
Further, the particle size of the fine particles is preferably 0.2 or less when the particle size of the resin-coated carrier is 1, in order to obtain uniform coating of the fine powder.

It is preferable that the resin-coated carrier has a sharp particle size distribution in order to obtain uniform coating of the fine powder.

When the particle size of the resin-coated carrier is Rgm, R±lo
g m in particle size distribution of 40% or more, more preferably 50%
It is preferable that resin-coated carrier particles are included.

Particle size and particle size distribution can be measured using Luzex (trade name), which is measured by optical reading, or by dispersing the powder in a liquid medium and measuring the particle size from the electrical signal when it passes through the orifice of an aperture. The desired volume average particle diameter and volume particle size distribution are measured using a Coulter Counter (manufactured by Coulter Inc.), an Elzone Particle Counter (manufactured by Verticle Data Inc., USA), or the like.

Note that it is preferable that the resin-coated carrier has a spherical shape in order to uniformly cover the particles A.

In the present invention, the triboelectrification series of carrier particles (hereinafter referred to as carrier particles B) in which particles A are attached to a resin-coated carrier is located between particles A and toner particles (hereinafter referred to as toner particles C). This is achieved by
The triboelectricity of each particle can be set in accordance with the present invention by selecting particles with a triboelectric charge amount measured by the triboelectric charge measurement method described later, and as a result, it is possible to achieve the charging series according to the present invention. This makes it possible to prevent image defects caused by internal contamination due to toner scattering, which is the object of the present invention. The above effects cannot be obtained with a charging system other than the above.

The charging series is determined using the apparatus shown in FIG. 5 by the method described below.

That is, in the apparatus shown in FIG.
Toner particles C and carrier particles B whose triboelectric charge amount is to be measured are placed in a metal measuring container 62 equipped with a wire screen 63 with a mesh size (usually 400 meshes) that allows toner particles C2 and particles A to pass through. Alternatively, about 4 g of a well-mixed mixture of particles A and carrier particles B at a weight ratio of 1:9 (carrier particles B is 9) is added, and metallic phthalo 4 is applied. The weight of the entire measurement container 62 at this time is W
+ (g). Next is suction machine 6! (At least the part in contact with the measurement container 62 is an insulator), suction is drawn from the suction port 67, and the air volume adjustment valve 66 is adjusted to set the pressure of the vacuum gauge 65 to 700 m5HH. In this state, suction is performed sufficiently (for about 1 minute or until there is almost no change in the potential of the electrometer 69) to remove toner particles C or particles A. The potential of the electrometer 69 when removed is V (volt). Here, 68 is a capacitor whose capacity is C (μF), and the weight of the entire measurement container after suction is W2 (g).

Through the above operations, the triboelectric charge amount T (μC/g) of toner particles C or particles A is calculated as shown in the following formula.

xv T (μc/g) = w, -w 2 However, the measurement conditions are 23° C. and 60% RH.

In the present invention, the charging series of carrier particles B is located between particles A and toner particles C.
This means that the charge of triboelectric charge T (Particle) of particle A against carrier particle B and the charge of triboelectric charge T (Taner) of toner particle C relative to carrier particle B have opposite polarity. Since the reference value is 0, the triboelectrification series is as follows: Toner particles C, Carrier particles B, Particles A, or Toner particles C>Carrier particles B>Particles A.

Note that toner particles C to be mixed with carrier particles B according to the present invention can be of known types, and are preferably styrene-based resins, polyester-based resins, or epoxy-based resins with internal additions of colorants, charge control agents, etc. It is possible to use a toner in which a toner is dispersed, a capsule toner, a polymerized toner in which toner particles are suspended polymerized particles, and the like.

Further, other external additives, preferably silica, are added to the developer in which carrier particles B and toner particles C are mixed.

A fluidizer such as alumina, TiO□, and an abrasive can be added.

The carrier particles B according to the developer of the present invention may be produced by any production method as long as it can form a structure in which the particles C are attached to the resin-coated carrier as described above, but the following preferred method is used. The manufacturing method is described below.

This adhesion method consists of two steps: a pretreatment step in which particles A, such as pigments, are dispersed and uniformly adhered to the resin-coated carrier, and a step in which the adhered particles A are immobilized by impact force.

The pretreatment involves dispersing the particles A and making them adhere to the resin-coated carrier by friction with the resin-coated carrier by electrostatic force (and van der Waals force), using a mixer equipped with high-speed stirring blades. However, it is acceptable as long as it has a mixing function and a dispersion function.

Figure 1 shows an example of a mixer equipped with high-speed stirring blades, but the pretreatment requires good dispersion of both particles A and the resin-coated carrier, and that the respective particles are not substantially crushed. be.

For this reason, although it is determined by the physical properties of the material, for toner materials, the processing temperature is preferably 0 to 50 DEG C., the rotation speed around the blades is 5 to 50 m/sec, and the processing time is preferably 1 minute to 60 minutes. Also, when performing such processing,
Since the temperature rises due to stirring, cooling the jacket and
It is preferable to cool the premises by supplying cooling air.

This pretreatment equipment does not need to be a mixer with high-speed stirring blades, as long as it has dispersion and mixing functions and has a sufficiently long residence time. In addition to 0 or more, which may be used by reducing the impact force so as to satisfy the above conditions, particles A may be dispersed in a liquid containing a resin-coated carrier, filtered and dried, and then fixed.

In such pretreatment, fluidity and dispersibility of the particles are important in uniformly adhering the particles A to the resin-coated carrier. That is, if the particles A exhibit strong aggregation, they cannot be separated into individual particles in the pretreatment step, and uniform adhesion tends to be difficult. Similarly, if the fluidity is extremely poor, it is similarly difficult to form individual particles and uniform adhesion is similarly difficult. In the case of particles A other than silica that have poor fluidity and dispersibility, use a method in which fine silica powder is added and mixed to the particles A in advance to improve fluidity and dispersibility and to make them adhere uniformly to the resin-coated carrier. The amount of silica fine powder added is preferably 0 based on the weight of mineral particles A.
-01 to 10% by weight, preferably 0.1 to 5% by weight. As such fine silica powder, hydrophobic fine silica powder treated with a positively or negatively charged silane coupling agent, a hydrophobic treatment agent, silicone oil, etc. is preferable.
It is preferable that the silica fine powder has a specific surface area of 40 to 40 h + 7 g as measured by a nitrogen gas adsorption method.
The degree of hydrophobicity measured by methanol titration test is 3.
Particularly preferred is 0-80% treated silica fine powder.

The "methanol titration test" defined herein for evaluating the degree of hydrophobicity of treated silica fine powder is carried out as follows. Sample silica fine powder 0.2g in capacity 250
Add to 50 sffi of water in a mj& Erlenmeyer flask.

Methanol is titrated from the burette until all of the silica is wetted. At this time, the solution in the flask is constantly stirred with a magnetic stirrer. The end point is observed when the entire amount of silica fine powder is suspended in the liquid,
The degree of hydrophobization is expressed as the percentage of methanol in the liquid mixture of methanol and water when the end point is reached.

Next is the method of immobilization, but it is not preferable that particles A such as crushed pieces of the resin-coated carrier or pigments are released, or that the particles A that have been attached are re-released, so that the immobilization can be done more reliably. is preferred.

For this purpose, it is preferable to control the impact force within a range that does not crush the resin-coated carrier and the temperature within a range that does not cause fusion aggregation. An example of a fixing device for carrying out this method is a bottle mill with a recycling function and a large number of rotating bottles (see Figure 4-1), a rotating blade or hammer (rotating piece), and a liner (fixed piece). A crusher (second
= 1 and 3-1) is valid.

The circumferential speed of the tip of the rotating piece in this device is 30 to 130 m/
sec is preferred. The temperature varies depending on the physical properties of the resin-coated carrier and particles A, but is 10-100°C, preferably 30-100°C.
90℃ is good, and the residence time at the impact part is 0.02 sec.
N12 sec is preferable. In the case of a bottle mill, it is necessary to increase the concentration of powder. In the apparatus of the type shown in FIG. 2-1 or 3-1, the powder to be treated is collected near the liner by centrifugal force, so that the latitude of the powder concentration is wide. The shortest gap between the bottle mills or between the blade or the hammer and the liner is preferably about 0.5 to 7II11, more preferably 1m to 5cm, to obtain good results.

To explain in more detail with reference to FIG. 2-1, the resin-coated carrier and particles A are introduced from the inlet 24, pass through the inlet chamber 20, and pass along the rotating dispersion blade 14 between the rotating blade 15 and the liner 18. Impact part 19 (No. 2-2
(shown in the partially enlarged view of the figure), passes through the outlet chamber 21, passes through the return path 22 and the blower 25, and circulates through the same circuit again. After the immobilization process is completed, the product is taken out from the product takeout port 23.

Here, the powder consisting of the resin-coated carrier and particles A receives an impact between the blade 15 and the liner 18 in the impact section 19 due to mechanical energy and thermal energy in which a part of the mechanical energy is converted into heat. A part of the resin-coated carrier and particles A are melted or softened to undergo a fixation treatment. Here, if necessary, it is preferable to flow cooling water into the jacket 26 to adjust the ambient temperature. In FIG. 2-2, the gap a between the blade 15 and the liner 18 is the shortest gap, and the space corresponding to the width of the blade 15 is the impact portion.

Figure 3-3 shows the positional relationship between the liner 29 of the immobilization device and the rotating rotor 31. Rotor 3! refers to the difference in the radius of two circles: the circumference 51 obtained by connecting the tips and the locus 52 of the protrusion of the rotor 31. The same applies if a blade or hammer is used instead.

FIG. 4-2 is a schematic view of a bottle in a bottle mill type fixing device as seen from the front of the device, and the gap 55 between the fixed bottle 39 and the rotating bottle 54 is the shortest gap. In addition, 57
indicates the maximum gap, and 56 indicates the trajectory of the rotating bin 54.

[Example] Example 1 A layer of spherical ferrite particles with a particle size of 50μ was coated with a fluorine-containing acrylic resin and an epoxy resin to obtain a spherical resin-coated carrier with a particle size of 51μ (resin content: 3% by weight). . The particle size distribution was a volume particle size distribution, and 52% of the resin-coated carrier was contained in 51±10 μm.

To 100 parts by weight of this resin-coated carrier, a layer of manganese oxide (m ) Mn having a particle size of 0.5 μ was added. Particle (particle A) (
3 parts by weight of volume resistivity 5×10'ΩC■) were added and treated at 30a+/sec for 6 minutes using a mixer as shown in FIG. 1 to uniformly mix particles A and the resin-coated carrier.

Next, using the apparatus shown in Fig. 2-1, the minimum gap was 1 mm%, the speed was 70 m/sec, the ambient temperature was 70°C, and the
Processed for minutes. When observed using an electron microscope, it was observed that the particles A were uniformly and firmly held on the resin-coated carrier.

To 100 parts by weight of the carrier particles 8 thus obtained, 3 parts by weight of styrene resin toner particles 0 containing nigrosine and carbon black and 0.5 parts by weight of silica were uniformly mixed to obtain a developer.

When the developer was put into a modified NP-3525 machine (Canon) and subjected to a durability test of about 10,000 sheets, almost no contamination inside the machine due to toner scattering was observed.

Further, when the amount of triboelectric charge was measured using the measuring device shown in FIG. 5, the amount of triboelectricity T (Particle) of manganese oxide Mn, 03 grain particles with respect to carrier particle B was -
At 7 μC/g, the amount of triboelectric charge T (Taner) of toner particles C with respect to carrier particles B was +z3uc/g. That is, the triboelectric charging series was toner particles C>carrier particles B>particles A.

Example 2 Silicone resin and 7
Coated with enol resin, particle size 46 μ■ (resin content 3
% by weight) was obtained. The particle size distribution is
The volume particle size distribution was 46±10μ haze containing 56% resin coated carrier.

To 100 parts by weight of this carrier, aluminum oxide^1ids (electrical resistance 7x10') treated with aminosilane
Ωcm) 3 parts by weight of particles A were added, and the mixture was treated at 25 m/sec for 7 minutes using a mixer as shown in FIG.

Next, using the apparatus shown in FIG. 2-1, the treatment was carried out for 8 minutes at a minimum gap of -1 ug and at a speed of 75 m/sec. The internal temperature (ambient temperature) was 70°C.

When observed under an electron microscope, it was observed that particles A were firmly held by the coated carrier.

To 8,100 parts by weight of the carrier particles thus obtained, 03 parts by weight of polyester resin toner particles containing a charge control agent and carbon black and 0.4 parts by weight of silica were uniformly mixed to obtain a developer.

When the developer was subjected to a durability test of about 10,000 sheets using a modified machine of NP-7050 (Canon family), almost no contamination inside the machine due to toner scattering was observed.

In addition, when the amount of triboelectric charge was measured using the measuring device shown in Fig. 3g5, the amount of triboelectricity T (Particle
) Lotus is 14μGag, and the amount of triboelectric charge T (Toner) of toner particles C against carrier particles B is -14μ
C/g. In other words, the triboelectrification series is toner particles C
〉Carrier particles B〉Particles A〉.

〔Effect of the invention〕

As explained above, the particles A are attached to the surface of the resin-coated carrier so that the triboelectrification series becomes toner particle C<carrier particle B<particle A or toner particle C>carrier particle B>particle A. After that, as carrier particles B,
By mixing it with toner particles C to form a developer, when the developer is used in electrographic photography or the like, there is almost no internal contamination due to toner scattering, and high-quality images can be obtained.

Further, the carrier particles B of the developer can be easily produced under predetermined conditions using impact force from a rotating piece or the like.

[Brief explanation of the drawing]

FIG. 1 is a diagram schematically showing an example of a stirring device for mixing resin-coated carrier and particles A, and FIG.
The figure is a diagram schematically showing an example of an apparatus for immobilizing particles A on the surface of a resin-coated carrier, and FIG. 2-2 is a partially enlarged view of the apparatus in FIG. Figure-1 is a diagram schematically showing another example of an apparatus for immobilizing particles A on a resin-coated carrier, and Figures 3-2 and 3-3.
The figure is a partial view of the apparatus shown in Fig. 3-1, and Fig. 4-1 is a diagram schematically showing an example of a bottle mill type apparatus for immobilizing particles A on a resin-coated carrier. FIG. 4-2 shows a partial view of the device shown in FIG. 4-1, and FIG. 5 is a diagram schematically showing an example of the device for measuring the amount of triboelectric charge. 1... Jacket 2... Stirring blade 3 - Motor 4 - Lid 5 - Base 6... Control plate 7... Cylinder 8... Lid lock 9... Cylinder IO... Direction control Unit 11--Discharge port 12--Rotating shaft 13
-... Rotor 14... Dispersion blade 15.
...Rotating piece (blade) 1B...Partition disk 17-
...Casing I B-...Liner 19-
・・Impact part 20−・・Entrance chamber 21−・・・
Exit chamber 22-... Return path 23-...
Product take-out valve 24... Raw material input valve 25-...
Blower 26-・Jacket 27-・Rotating shaft
2 B-...Casing 29-...Liner
30...3 blower blades...Rotor (with blades) 32-...Outlet 33-...Raw material input port
34...Return path 35--Product outlet 3
B-...Entrance 37-Jacket 38-...
Casing 39 - Fixed bottle 40 - Inlet 41 - Raw material input port 42 - Circulation blower 43 - Return path 44 - Product extraction port 4
5-- Outlet 47--Rotating shaft 51--Circumference 54--Rotating bin 57--Maximum gap 62--Measuring container 6--Absorber 8 B--Air volume adjustment valve 69-- ...Electrometer 46--Rotor 48--Jacket 56.52--Trajectory 55--Shortest gap 63--Wire mesh screen 64--Metallic phthalo 7--Suction port 65--Vacuum Total 611-- Capacitor patent applicant Canon Co., Ltd.

Claims (1)

[Scope of Claims] 1. A developer containing at least toner particles and carrier particles formed by holding fine powder particles on the surface of a carrier coated with a resin, the developer having a triboelectrification series. A developer characterized in that: toner particles>carrier particles>fine powder particles, or toner particles<carrier particles<fine powder particles. 2. 0 for the resin-coated carrier and the carrier
．． Fine powder particles having a particle size ratio of 2 or less are heated at an ambient temperature of 1
Under conditions of 0 to 100℃, the rotation piece and fixed piece or two
The seeds are passed through an impact part having a minimum gap of 0.5 to 7 mm to obtain carrier particles with the fine powder particles held on the surface of the carrier, and the carrier particles and at least A method for producing a developer, characterized in that toner particles are mixed and their triboelectrification series is toner particles>carrier particles>fine powder particles, or toner particles<carrier particles<fine powder particles.