JPH05281782A - Negatively charged toner and image forming method - Google Patents

Abstract

PURPOSE:To provide the negatively charged toner which can be fixed at a low temp., can be improved in filming resistance, can impart adequate negative chargeability to a silica untreated toner, can improve the flow property of the silica untreated toner and can decrease the toner spent to a carrier and the image forming method by which an image having good image quality is obtd. when a toner recycling system is adopted. CONSTITUTION:This negatively charged toner is formed by fixing resin particulates having the softening point higher than the softening point of a binder resin and <=160 deg.C and contg. fluorinated alkyl (meth)acrylate at a ratio higher than 30wt.% by mechanical impact force to base material particles consisting of a resin chemically bonded with crystalline polyester and amorphous vinyl polymer as a binder. The negatively charged toner is used in the image forming method which adopts the recycling system having a recycling mechanism 29 to recycle the toner.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a negatively chargeable toner and an image forming method.

[0002]

2. Description of the Related Art As a method of forming a visible image from image information, a method of passing an electrostatic latent image such as an electrophotographic method, an electrostatic recording method and an electrostatic printing method is widely used. For example, in electrophotography, a uniform electrostatic charge is applied to a latent image carrier having a photosensitive layer made of a photoconductive material, and then an electrostatic latent image corresponding to the original is formed on the surface of the latent image carrier by image exposure. An image is formed, and the electrostatic latent image is developed with a developer to form a toner image. This toner image is transferred to a recording material such as paper and then fixed by heating or pressing to form a copied image. On the other hand, the latent image carrier after the transfer step is destaticized, the residual toner on the latent image carrier is then cleaned, and the latent image carrier is provided for the formation of the next copy image.

In recent years, there has been a strong demand for development of a toner capable of fixing at a lower temperature than ever before due to the demand for downsizing of a high-speed copying machine or copying machine and reduction of power consumption. That is, in a high-speed copying machine, when a large number of sheets are continuously copied, the heat of the heat roller is deprived of the transfer paper and the heat supply cannot be made in time, and as a result, the temperature of the heat roller is lowered and the fixing failure is likely to occur. Therefore, it is necessary to use a heat roller with a large heat capacity and to heat it with a heater with a maximum maximum power consumption, but doing so has drawbacks such as a long warm-up time, an increase in the size of the fixing device, and an increase in power consumption. come. Furthermore, since the transfer paper heated and pressed through the fixing device curls due to evaporation of water in the paper and pressure, the development of a toner that can be fixed at low temperature to improve the transfer reliability of the transfer paper Is strongly desired.

On the other hand, when the heat roller fixing method is adopted, the toner comes into contact with the surface of the heat roller in a molten state at the time of fixing, but when the viscoelasticity of the molten toner is too small or too large, the molten toner is A part of the toner is transferred and adhered to the surface of the heat roller, and this is transferred again to the transfer paper sent next and stains the image, so-called offset phenomenon occurs. The offset phenomenon includes an under-offset that occurs when the toner is insufficiently heated and a hot offset that occurs when the toner is excessively heated. The toner has a minimum fixing temperature at which fixing is possible and a hot offset phenomenon. It is preferable that the fixing temperature range of the maximum temperature range that does not occur is wide. Further, the toner is required to be able to exist stably as a powder without aggregation under the conditions of use or storage environment, that is, to have excellent blocking resistance.

Further, in order to form an image of good quality, it is necessary that the toner has a high fluidity and an appropriate charging property. As a technique for improving the fluidity and chargeability of the toner, it is known to add inorganic fine particles such as silica fine particles to the toner component.
However, the toner to which the inorganic fine particles such as the silica fine particles are added is subjected to mechanical stress when being stirred and mixed in the developing device, and the silica fine particles are embedded in the toner particles. It had a drawback that the property deteriorated. Further, in recent years, in order to reduce the running cost of toner, an image forming method that employs a so-called toner recycling system in which toner is collected and reused by cleaning has become widespread. It is necessary to maintain sufficient fluidity and chargeability even if the silica fine particles on the toner surface are buried.

The following toners are conventionally known. JP-A-63-27855 and JP-A-63-27
Japanese Patent No. 856 describes a toner using a block resin or a graft copolymer of a crystalline polyester and an amorphous vinyl polymer as a binder resin. Japanese Patent Application Laid-Open No. 2-198455 discloses a negatively charged developer comprising a toner in which positively chargeable resin fine particles are fixed to a mother particle having the above-mentioned copolymer as a binder resin by mechanical impact force and a positively chargeable carrier. Is listed. Japanese Patent Application Laid-Open No. 3-170946 describes a method for producing a toner in which a fluorine-based resin powder is fixed on the surface of toner fine particles.

[0007]

However, in the above technique, the crystalline polyester filmed on the latent image carrier or the developer transport carrier, so that an image such as uneven image density due to poor cleaning or poor developer transport was formed. There was a defect that defects occurred. Further, since a large amount of a substance that melts at a low temperature is contained, the toner is likely to adhere to the carrier and toner spent is likely to occur. In the above technique, positively chargeable resin fine particles are fixed on the surface, and silica fine particles are further added to form a negatively charged developer. Therefore, the negative chargeability is very high in the state where silica is not added (silica untreated). small. Therefore, in particular, when toner that is frequently subjected to mechanical stress returns to the developing device again, such as an image forming apparatus that employs a toner recycling system, or an apparatus having a developing device that structurally severely stresses, silica is used. However, there is a drawback in that the toner is buried in the toner and the negative charging property is greatly reduced.

Further, when silica is buried, the toner spent on the carrier is likely to proceed and the fluidity is also deteriorated, so that the charge rising characteristics are deteriorated and the developability is deteriorated. Good images with high density cannot be obtained. In the above-mentioned technique, since the negative chargeability of tetrafluoroethylene (PTFE) or fluorinated graphite is very strong, it is difficult to control the negative charge amount of the toner to which they are fixed to an appropriate value. Further, since the melting points of tetrafluoroethylene and fluorinated graphite are too high, there is a drawback that the low temperature fixability and the releasability are deteriorated.

The object of the present invention is that fixing at low temperature is possible, filming resistance can be improved, proper negative chargeability can be imparted to untreated silica toner, and fluidity of untreated silica toner can be improved. Another object of the present invention is to provide a negatively chargeable toner that can reduce the toner spent on the carrier. Another object of the present invention is to provide an image forming method capable of obtaining an image with good image quality when a toner recycling system is adopted.

[0010]

In order to achieve the above object, the negatively chargeable toner of the present invention is a base particle which uses as a binder a resin in which a crystalline polyester and an amorphous vinyl polymer are chemically bonded. In addition, resin fine particles having a softening point higher than the softening point of the binder resin and 160 ° C. or less and containing more than 30% by weight of a fluorinated alkyl (meth) acrylate were fixed by mechanical impact force. Is characterized by. The image forming method of the present invention is characterized in that the negatively chargeable toner is used in the image forming method employing a recycling system for reusing toner.

[0011]

The negatively chargeable toner according to the present invention has proper negative chargeability even if silica fine particles are not added by adhering specific resin fine particles to the base particles, so that silica is buried in the toner. Negative chargeability does not decrease. Therefore, it can be particularly preferably used in an image forming apparatus that employs a toner recycling system that returns the cleaned toner to the developing device. Further, since the surface energy of the specific resin fine particles adhered to the surface is smaller than that of the base particles, the toner spent on the carrier is significantly reduced and the fluidity of the toner is improved.

The present invention will be described in detail below. [Negatively Chargeable Toner] In the present invention, a resin in which a crystalline polyester and an amorphous vinyl polymer are chemically bonded is used as the binder resin of the base particles. Specifically, JP-A-63-27855 and JP-A-63-
As described in JP-A-27856, a block copolymer or a graft copolymer of a crystalline polyester and an amorphous vinyl copolymer having a functional group bonded to the crystalline polyester can be preferably used.

In the present invention, the resin fine particles constituting the toner have a softening point higher than the softening point of the binder resin of the base particles and 160 ° C. or less, and 30% by weight of fluorinated alkyl (meth) acrylate. Resin fine particles containing a larger amount are used. That is, the softening point of the resin fine particles needs to satisfy the following relational expression. The softening point of the binder resin of the base particles <the softening point of the resin fine particles ≤ 160 ° C. When the softening point of the resin fine particles satisfies the above relational expression,
The filming resistance is improved, and the low temperature fixing property and the releasing property are improved. When the softening point of the resin fine particles is lower than the softening point of the binder resin of the base particles, the resin fine particles are excessively deformed and sufficient filming resistance cannot be obtained. On the other hand, when the softening point of the resin fine particles exceeds 160 ° C., the low temperature fixability and releasability are deteriorated. The glass transition point of the resin fine particles is preferably 55 ° C. or higher. Glass transition point is 5
If it is 5 ° C or higher, blocking resistance is improved.

The repeating unit of the fluorinated alkyl (meth) acrylate is represented by the following chemical formula 1.

[0015]

[Chemical 1] In the above Chemical Formula 1, R ¹ is a hydrogen atom, a methyl group, or R
² represents a residue in which a hydrogen atom of a hydroxyl group of an alcohol compound containing an alkyl group in which at least one of hydrogen atoms has been replaced by a fluorine atom is removed.

In the above chemical formula 1, examples of the alcohol compound capable of forming the residue represented by R ² include 1 to 1 carbon atoms.
18 perfluoroalcohols, 1,1 represented by the following formula
- dihydro perfluoro alcohol or tri hydroperoxide _{fluoroalcohol, CF 2 X (CF 2)} n CH 2 OH (. Where, n is an integer of 0 to 16, X represents a hydrogen atom or a fluorine atom) represented by the following formula that tetrahydronaphthyl perfluoro _{alcohol, CF 3 (CF 2) n} (CH 2 CH 2) (CF 2) m OH ( where, n is an integer of 0 to 15, m represents 0 or 1.) other fluoroalcohol ( For example, 2, 2,
3,3,4,4-tetrafluoropropanol, 1,
1, ω-trihydroperfluorohexanol, 1,
1, ω-trihydroperfluorooctanol, 1,
1,1,3,3,3-hexafluoro-2-propanol etc.), acetyl alcohol (eg 3-perfluorononyl-2-acetylpropanol, 3-perfluorolauryl-2-acetylpropanol etc.), N- Fluoroalkylsulfonyl-N-alkylaminoalcohol (eg, N-perfluorohexylsulfonyl-N
-Methylaminoethanol, N-perfluorooctylsulfonyl-N-methylaminoethanol, N-perfluorodecylsulfonyl-N-methylaminoethanol, N-perfluorolaurylsulfonyl-N-ethylaminoethanol, etc.) You can

Preferred examples of the repeating unit represented by the above chemical formula 1 include those shown below. These may be used alone or in combination of both.

[0018]

[Chemical 2]

[0019]

[Chemical 3]

In the above Chemical Formula 2 and Chemical Formula 3, R ¹ represents a hydrogen atom or a methyl group, n and p represent an integer of 1 to 8, and m and q represent an integer of 1 to 19. As the fluorinated alkyl (meth) acrylate repeating unit used in the present invention, the following are particularly preferable.

[0021]

[Chemical 4]

[0022]

[Chemical 5]

[0023]

[Chemical 6] In Formula 4, Formula 5, and Formula 6, R ¹ represents a hydrogen atom or a methyl group.

The fluorinated alkyl (meth) acrylate-based copolymer may be a copolymer containing the above repeating unit alone, or may further contain another repeating unit. Such other repeating units include repeating units derived from aliphatic olefins (eg, ethylene, propylene, butene-1), halogenated aliphatic olefins (eg, vinyl chloride, vinyl bromide, 1,
Repeating units derived from 2-dichloroethylene, allyl chloride, etc., conjugated diene-based aliphatic diolefins (eg, 1,3-butadiene, 2,3-dimethyl-1,3-)
Repeating units derived from butadiene, etc., aromatic vinyl compounds (eg, styrene, methylstyrene, etc.)
And a repeating unit derived from a nitrogen-containing vinyl compound (for example, 2-vinylpyridine, 2-vinyl-6-methylpyridine, etc.). These may be used alone or in combination of two or more. As the repeating unit, styrene, methylstyrene, and methyl (meth) acrylate are particularly preferable.

In the present invention, the content ratio of the fluorinated alkyl (meth) acrylate in the resin fine particles is 30.
It is necessary to have more than wt%. By containing the fluorinated alkyl (meth) acrylate in an amount of more than 30% by weight, it is possible to impart appropriate negative chargeability and sufficient fluidity to the silica-treated toner, and even if silica fine particles are buried in the toner. Negative chargeability and fluidity do not deteriorate. In addition, the toner spent on the carrier is significantly reduced.

The average particle diameter of the primary particles of the resin fine particles is 0.02 to 0.6 μm in order to improve the adherence to the base particles.
Is preferred. However, the average particle diameter of the primary particles is measured by observing with a scanning electron microscope (SEM) at a magnification of tens of thousands. The coverage of the base particles with the resin fine particles is 10 to 10 in order to fully exert the effect of the resin fine particles.
90% is preferable. Here, the coverage is defined by the following mathematical expression 1.

[0027]

[Equation 1] ρ _t : Specific gravity of base particles ρ _p : Specific gravity of resin fine particles D _t : Particle diameter of base particles D _p : Particle diameter of resin fine particles C: Concentration of resin fine particles (%)

In addition to the binder resin, the base particles contain other toner components such as a colorant, a wax and a magnetic material, if necessary. As the colorant, for example, carbon black, chrome yellow, DuPont oil red, quinoline yellow, phthalocyanine blue, malachite green oxalate, etc. can be used.
As the wax, polyolefin wax such as low molecular weight polyethylene and polypropylene, paraffin wax, ester wax, amide wax and the like can be used. As the magnetic substance, a ferromagnet such as ferrite or magnetite, a metal or an alloy exhibiting ferromagnetism such as cobalt, nickel, or a compound containing these elements can be used. This magnetic material is used to obtain a magnetic toner.

In the present invention, the resin fine particles are fixed to the base particles by a mechanical impact force to form a negatively chargeable toner. The state in which the resin fine particles are fixed to the surface of the base particles means The height of the resin fine particle portion protruding from the surface of the base particle is 15 to 95 times the diameter of the resin fine particle.
It means the state of being%. Note that such a state can be easily confirmed by observing the surface of the toner particles with a transmission electron microscope or a normal electron microscope. In order to obtain such a state, in a system in which the base particles and the resin fine particles are both present, an impact force of a size that does not allow the base particles to be crushed, for example, 1/5 to 1/1 of the force normally required at the time of crushing. A mechanical impact force having a magnitude of 10 may be applied. Specifically, depending on the characteristics of the resin contained in the base particles as a binder, the base particles 1
1.59 × 10 ^{−3 to} 9.56 × 10 ⁻⁵ erg per piece,
Preferably 1.20 × 10 ^{−3 to} 1.60 × 10 ⁻⁴ erg
The mechanical impact force may be applied.

As a device for applying such a mechanical impact force, a super mill, a ball mill, an ong mill, a Henschel mixer, a hybridizer or the like can be used. Figure 1 shows an example of a hybridizer,
1 is a powder charging valve, 2 is a powder charging chute, 3 is a circulation circuit, 4 is a casing, 5 is a rotating disk, 6 is a blade, 7 is a stator, 8 is a jacket for cooling or heating, and 9 is powder discharging. The chute 10 is a powder discharge valve. The arrows indicate the loci of powder. When the rotary disk 5 having the blades 6 is rotated at a high speed, a centrifugal force acts on the internal air by the blades 6, so that the outside of the rotary disk 5 is in a pressurized state and the central portion of the rotary disk 5 is in a negative pressure state.

Then, by the circulation circuit 3, the rotary disk 5
Since the outer side and the central part are connected to each other, the pressurized air on the outer side of the rotary disk 5 moves to the central part of the rotary disk 5 through the circulation circuit 3 to form a circulating flow of air. In a state in which such a circulating flow of air is formed, when a mixture of the mother particles and the resin fine particles is charged from the powder charging chute 2 provided in the middle of the circulating circuit 3, the mixture flows together with this circulating flow in the circulating circuit. 3, the mixture collides with the blade 6 and receives a mechanical impact force, whereby the resin fine particles are fixed to the surface of the base particle. After performing such a circulation process for a certain period of time, when the powder discharge valve 10 is opened and the processed product is discharged by centrifugal force,
The treated particles in which the resin fine particles are firmly adhered to the surface of the base particles can be obtained. In the circulation process, the circulation circuit 3 and the powder discharge chute 9 may be cooled or heated by the jacket 8 provided on the stator 7 side in order to control the temperature inside the apparatus. In this hybridizer, the peripheral speed of the turntable 5 is preferably 50 to 90 m / sec, the product temperature is preferably 20 to 60 ° C., and the treatment time is 1 to 1
0 minutes is preferred.

In the present invention, the negatively chargeable toner may be composed of the treated particles obtained as described above, and inorganic fine particles and external additives such as lubricants may be further added and mixed to the treated particles. Then, a negatively chargeable toner may be formed. Examples of the inorganic fine particles include silica, alumina, titania, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, cerium oxide, antimony trioxide, zirconium oxide, silicon carbide and silicon nitride. You can
Of these, silica fine particles are particularly preferable, and those that have been subjected to a hydrophobic treatment are more preferable. The amount of the inorganic fine particles used is preferably 0.01 to 5% by weight, and more preferably 0.05 to 2% by weight, based on the whole toner.

As the lubricant, for example, zinc stearate,
Aluminum stearate, lithium stearate, stearic acid, hydrogenated castor oil and the like can be used. The amount of the lubricant used is preferably 0.01 to 2% by weight based on the whole toner. These external additives may be added and mixed together with the resin fine particles, or may be added and mixed after fixing the resin fine particles.

The negatively chargeable toner of the present invention may be mixed with a carrier and used as a two-component developer, or may be mixed with a carrier and used as a one-component developer. As a carrier constituting the two-component developer, a conventionally known carrier can be used. However, since the toner of the present invention has a negative charging property, a ferromagnetic metal such as iron, nickel or cobalt, or a metal thereof is used. Particles of ferromagnetic metal compounds such as alloys, ferrite, magnetite, etc., containing styrene resin,
Acrylic resin, styrene-acrylic copolymer resin,
A carrier coated with a silicone resin or the like can be preferably used. The average particle size of the carrier is 20 to
200 μm is preferable, and 30 to 150 μm is particularly preferable.

In the present invention, the softening point is 20 kg / cm ² with a plunger while heating a 1 cm ³ sample at a temperature rising rate of 6 ° C./minute using a “Koka type flow tester” (manufactured by Shimadzu Corporation). 1mm diameter, 1 length
A nozzle of mm is pushed out to draw a plunger drop amount-temperature curve (softening flow curve) of a flow tester, and the temperature corresponding to h / 2 when the height of the S-shaped curve is h. In the present invention, the glass transition point is a value measured based on a differential scanning calorimetry (DSC), and specifically, "DSC-20" (manufactured by Seiko Denshi Kogyo Co., Ltd.) is used and the temperature rising rate is 10 When measured at ° C / min,
It is the temperature at the intersection of the extension line of the baseline below the glass transition point and the tangent line showing the maximum slope between the rising portion of the peak and the apex of the peak.

[Image Forming Method] Next, the image forming method of the present invention will be described. FIG. 2 shows an image forming apparatus that can be used for carrying out the image forming method of the present invention. Around the latent image carrier 20 having a positively charged organic photoconductive photosensitive layer,
A strip electrode 21, a developing mechanism 22, a transfer separation electrode 23, a cleaning mechanism 24, and a charge eliminating lamp 25 are arranged. The recording material from the paper feeding mechanism 26 is conveyed by the conveying mechanism 27, and after receiving the transfer of the toner image by the transfer separation electrode 23,
An image is formed by being fixed by the fixing mechanism 28. The toner remaining on the latent image carrier 20 after the transfer is scraped and removed by the cleaning mechanism 24. The collected toner is returned to the developing mechanism 22 by the recycling mechanism 29 and reused. Hereinafter, each step will be described.

(Developing Step) A one-component developer or a two-component developer constituted by using a toner in which resin fine particles are fixed as an essential component is conveyed to a developing area by a developer conveying carrier, and the latent image is formed by the developer. The electrostatic latent image on the carrier is developed to form an unfixed toner image. As a developing method,
There is no particular limitation, and a conventionally known method can be applied. Specifically, the following methods can be mentioned. (1) Contact Magnetic Brush Development Method In this method, as shown in FIG.
A magnetic brush made of a developer having a height higher than that of the gap in the developing area is formed on the magnetic brush, and the magnetic brush is conveyed to the developing area to rub the electrostatic latent image on the latent image carrier 20 while the magnetic brush is moving. The toner is attached to the electrostatic latent image and development is performed. 3
Reference numeral 2 is a main stirring roller, 33 is an auxiliary stirring roller, 34 is a toner conveying screw, 35 is a spike-up regulating plate, and 36 is a doctor blade. (2) Jumping magnetic brush developing method In this method, a magnetic brush of developer having a lower bristling than the gap of the developing area is formed on the developer carrying carrier, and the magnetic brush is carried to the developing area, and at the same time, the developing area. By applying an oscillating electric field to the toner, the toner in the magnetic brush is made to fly and adhered to the electrostatic latent image for development. (3) Cascade development method

(Transfer Step) The unfixed toner image on the latent image carrier obtained by development is transferred to a recording material. In this transfer step, either an electrostatic transfer method or a bias transfer method can be applied, but the electrostatic transfer method is particularly preferable. Specifically, for example, a transfer device for generating a DC corona discharge is arranged so as to face the latent image carrier through the recording material, and the DC image is applied by applying a DC corona discharge from the back side of the recording material. The unfixed toner image carried on the surface of the body is transferred to the surface of the recording material.

(Cleaning Step) After the transfer step, the toner remaining on the latent image carrier is cleaned. The cleaning means is not particularly limited, but a cleaning device having a cleaning blade placed in contact with the surface of the latent image carrier is preferable. According to this cleaning device, the surface of the latent image carrier is rubbed by the cleaning blade to scrape and remove the residual toner.

(Recycling Step) The toner collected by cleaning is returned to the developing mechanism again by an appropriate recycling system and reused. FIG. 4 is an explanatory diagram showing an example of the recycling system. 20 is a latent image carrier, 22 is a developing mechanism, 24 is a cleaning mechanism, 29 is a recycling mechanism, 41 is a magnetic brush mechanism, 42 is a toner receiving and distributing mechanism, 43 is a screw conveyor, 44 is a first screw, and 45 is a second screw. It is a screw. In the apparatus of this example, the toner from the screw conveyor 43 is supplied to the toner receiving and distributing mechanism 42 by the first screw 44 and the second screw 45.

That is, the first screw 44 and the second screw
Each of the screws 45 has a rotating shaft inside and a blade provided spirally along the rotating shaft. In the first screw 44, the toner sent from the screw conveyor 43 is moved along with the rotation of the rotating shaft. Are sequentially pushed up and sent to the second screw 45. In the second screw 45, the toner is sequentially sent in the horizontal direction by the same principle as the first screw 44, supplied to the toner receiving and distributing mechanism 42, and collected. The toner is again used for developing the electrostatic latent image on the latent image carrier 20.

(Fixing Step) The recording material on which the unfixed toner image has been transferred in the transfer step is subjected to a fixing process by a heat fixing mechanism to form a fixed toner image on the recording material.

[0043]

EXAMPLES Examples of the present invention will be described below together with comparative examples, but the present invention is not limited to these examples. [Crystalline Polyester 1] 1500 g of sebacic acid and 964 g of hexamethylene glycol were placed in a 5 liter round bottom flask equipped with a thermometer, a stirrer made of stainless steel, a nitrogen gas introduction tube made of glass and a flow-down condenser, This flask was set in a mantle heater, and nitrogen gas was introduced through a glass nitrogen introducing tube to raise the temperature in a state where the inside of the reactor was kept in an inert atmosphere. Then
13.2 g of p-toluenesulfonic acid was added and the temperature was adjusted to 150.
The reaction was carried out at ° C. When the amount of water flowing out by the esterification reaction reached 250 ml, the reaction was stopped and the reaction system was cooled to room temperature to obtain a crystalline polyester 1 made of polyhexamethylene sebacate having a hydroxyl group at the molecular end. This crystalline polyester 1 had a melting point Tm of 64 ° C. and a weight average molecular weight Mw of 14,000. The measuring method of the melting point Tm and the weight average molecular weight Mw is described in JP-A-63 / 1988.
It is the same as the method described in JP-A-27855 and 63-27856.

[Crystalline Polyester 2] Tm = 77 ° C., Mw =
A crystalline polyester 2 consisting of 8,370 polydecamethylene adipate was obtained.

[Amorphous vinyl polymer 1] 100 parts by weight of toluene was placed in a separable flask having a capacity of 1 liter,
Among them, as a monomer for high molecular weight component, styrene 75
Parts by weight, 25 parts by weight of n-butyl acrylate, and 0.2 parts by weight of benzoyl peroxide were added to replace the gas phase in the flask with nitrogen gas, and then the temperature was raised to 80 ° C. to reach the temperature. The first stage polymerization was carried out for 15 hours. In addition, M in the homopolymer of the monomer for the high molecular weight component is
The w is 461,000 and the glass transition point Tg is 61 ° C. Then, the inside of the flask was cooled to a temperature of 40 ° C., and 85 parts by weight of styrene, 10 parts by weight of n-butyl methacrylate, 5 parts by weight of acrylic acid, and peroxide were added thereto as a monomer for a low molecular weight component. After 4 parts by weight of benzoyl was added and stirring was continued for 2 hours at a temperature of 40 ° C., the temperature was raised again to 80 ° C. and the temperature was maintained for 8 hours to carry out the second stage polymerization. The homopolymer of the monomer for low molecular weight component has Mw of 8,200 and Tg of 64 ° C.

Next, 0.5 g of zinc oxide, which is a polyvalent metal compound, was added to the flask, and the reaction was carried out for 2 hours while stirring at a reflux temperature. Further, toluene is distilled off with an aspirator and a vacuum pump,
Amorphous vinyl polymer 1 was obtained in which zinc oxide was reacted with the carboxyl group of the vinyl polymer to form ionic cross-linking bonds. This amorphous vinyl polymer 1 has two peaks in the molecular weight distribution by GPC, the peak molecular weight on the high molecular weight side is 363,000, and the peak molecular weight on the low molecular weight side is 7,590. The Mw is 165,000, the ratio Mw / Mn is 25.9, the Tg is 62 ° C., and the softening point is 1.
It is 30 ° C.

[Binder Resin 1] 20 parts by weight of the crystalline polyester 1 80 parts by weight of the amorphous vinyl polymer 1 0.05 parts by weight of p-toluenesulfonic acid 100 parts by weight of xylene The mixture was placed in a bull flask and refluxed at a temperature of 150 ° C. for 1 hour, and then xylene was distilled off by an aspirator and a vacuum pump to obtain a binder resin 1 in which a crystalline polyester and an amorphous vinyl polymer were chemically bonded. Obtained. The binder resin 1 has a Tg of 60 ° C. and a softening point of 110 ° C.

[Binder Resin 2] 15 parts by weight of the crystalline polyester 1 85 parts by weight of the amorphous vinyl polymer 0.05 parts by weight of p-toluenesulfonic acid 0.05 parts by weight of xylene 100 parts by weight of the binder resin 1 In the same way as
Binder resin 2 having a Tg of 61 ° C. and a softening point of 115 ° C. was obtained.

[Binder resin 3] (for comparative example) Styrene-acrylic copolymer resin (Pryolite AC manufactured by Goodyear)

[Mother particle 1] Binder resin 1 100 parts by weight Carbon black (Mogal L, manufactured by Cabot) 10 parts by weight Paraffin wax 3 parts by weight (Sazol wax H1, manufactured by Sazol Marketing Co.) 3 parts by weight alkylenebis fatty acid amide Parts (Hoechst Wax C, manufactured by Hoechst Co., Ltd.) The above materials are mixed, melt-kneaded with a heating roll, cooled, coarsely crushed, and classified by an air classifier, and base particles 1 having an average particle size of 8.5 μm Got

[Mother particle 2] Mother particle 2 was obtained in the same manner as in the manufacture of mother particle 1 except that binder resin 1 was changed to binder resin 2.

[Mother particle 3] Mother particle 3 was obtained in the same manner as in the manufacture of mother particle 1 except that binder resin 1 was changed to binder resin 3.

[Resin Fine Particles 1] The fluorinated alkyl methacrylate represented by the following chemical formula 7 was polymerized to obtain resin fine particles 1 having an average primary particle diameter of 100 nm. The resin fine particles 1 have a glass transition point of 74 ° C. and a softening point of 158 ° C.

[0054]

[Chemical 7]

[Resin Fine Particles 2] 70 parts by weight of the fluorinated alkyl methacrylate shown in Chemical Formula 7 and 30 parts by weight of methyl methacrylate were polymerized to obtain resin fine particles 2 having an average primary particle diameter of 70 nm. The resin fine particles 2 have a glass transition point of 87 ° C. and a softening point of 120 ° C.

[Resin Fine Particles 3] 35 parts by weight of a fluorinated alkyl methacrylate represented by the following chemical formula 8 and 65 parts by weight of methyl methacrylate were polymerized to obtain resin fine particles 3 having an average primary particle diameter of 70 nm. The glass transition point and the softening point of the resin fine particles 3 are 98 ° C. and 148 ° C., respectively.

[0057]

[Chemical 8]

[Resin Fine Particles 4] 80 parts by weight of the fluorinated alkyl methacrylate shown in Chemical Formula 7 and 20 parts by weight of styrene are polymerized to obtain an average primary particle size of 100 nm.
Resin fine particles 4 of The resin fine particles 4 have a glass transition point of 78 ° C. and a softening point of 158 ° C.

[Resin Fine Particles 5] (For Comparative Example) 30 parts by weight of the fluorinated alkyl methacrylate shown in Chemical formula 7 and 70 parts by weight of styrene are polymerized to form resin fine particles 5 having an average primary particle diameter of 80 nm. Got The resin fine particles 5 have a glass transition point of 83 ° C. and a softening point of 156 ° C.

[Resin Fine Particles 6] (For Comparative Example) Tetrafluoroethylene represented by the following formula was polymerized to obtain resin fine particles 6 having an average primary particle diameter of 120 nm. CF ₂ = CF ₂

[Resin Fine Particle 7] (For Comparative Example) 2-2′-azobis (2-amidinopropane) dihydrochloride was used as a polymerization initiator, and 75 parts by weight of styrene, 5 parts by weight of methyl methacrylate, and n-butyl acrylate were used. 20
By weight part polymerization, resin fine particles 7 having an average primary particle diameter of 60 nm were obtained. The resin fine particles 7 have a glass transition point of 68 ° C. and a softening point of 150 ° C.

[Resin Fine Particles 8] (For Comparative Example) The resin fine particles 8 having an average primary particle diameter of 100 nm obtained by polymerizing the fluorinated alkyl methacrylate shown in Chemical Formula 7 above.
Got The resin fine particles 8 have a glass transition point of 74 ° C. and a softening point of 163 ° C.

[Example 1] Base particles 1 97 parts by weight Resin fine particles 1 3 parts by weight The above materials were agitated and mixed for 10 minutes by a high-speed agitating mixer "LMA-5" (manufactured by Nara Machinery Co., Ltd.) to give resin particles. Was electrostatically attached to the base particles. Next, these are "Nara Hybridization System NHS-1".
(Made by Nara Machinery Co., Ltd.)
A mechanical impact force was applied for 5 minutes at 000 rpm and a peripheral speed of 75 m / sec to obtain treated particles (silica untreated toner) obtained by fixing resin fine particles to the surface of the mother particles. The product temperature at this time was 43 ° C. Silica fine particles "R-972" are added to 100 parts by weight of the treated particles.
1.1 parts by weight (manufactured by Nippon Aerosil Co., Ltd.) and 0.1 part by weight of zinc stearate were added and mixed by a Henschel mixer to obtain Toner A (silica treated toner) of the present invention. In this toner A, the resin fine particles electrostatically adhered to the surface of the base particles are firmly fixed to the surface of the base particles by the surface observation with an electron microscope and the observation with a transmission electron microscope. It was recognized that

[Example 2] Base particles 2 97 parts by weight Resin fine particles 1 3 parts by weight By the same manner as in Example 1 using the above materials, treated particles were obtained. The treated particles were treated with "R-97" in the same manner as in Example 1.
2 ”and zinc stearate were added and mixed to obtain Toner B of the present invention.

[Example 3] Base particles 2 97 parts by weight Resin fine particles 2 3 parts by weight In the same manner as in Example 1 using the above materials, treated particles were obtained. The treated particles were treated with "R-97" in the same manner as in Example 1.
2 ”and zinc stearate were added and mixed to obtain toner C of the present invention.

[Example 4] 95 parts by weight of base particles 2 5 parts by weight of resin fine particles 3 Using the above materials, treated particles were obtained in the same manner as in Example 1. The treated particles were treated with "R-97" in the same manner as in Example 1.
2 ”and zinc stearate were added and mixed to obtain toner D of the present invention.

[Example 5] Base particles 2 97 parts by weight Resin fine particles 4 3 parts by weight In the same manner as in Example 1 using the above materials, treated particles were obtained. The treated particles were treated with "R-97" in the same manner as in Example 1.
2 ”and zinc stearate were added and mixed to obtain Toner E of the present invention.

[Comparative Example 1] Base particles 2 97 parts by weight Resin fine particles 5 3 parts by weight In the same manner as in Example 1 using the above materials, treated particles were obtained. The treated particles were treated with "R-97" in the same manner as in Example 1.
2 ”and zinc stearate were added and mixed to obtain a comparative toner a.

[Comparative Example 2] Base particles 4 97 parts by weight Resin fine particles 6 3 parts by weight In the same manner as in Example 1 using the above materials, treated particles were obtained. The treated particles were treated with "R-97" in the same manner as in Example 1.
2 ”and zinc stearate were added and mixed to obtain a toner b for comparison.

[Comparative Example 3] Base particles 1 95 parts by weight Resin fine particles 7 5 parts by weight In the same manner as in Example 1 using the above materials, treated particles were obtained. The treated particles were treated with "R-97" in the same manner as in Example 1.
2 ”and zinc stearate were added and mixed to obtain a toner c for comparison.

[Comparative Example 4] Base particles 2 97 parts by weight Resin fine particles 8 3 parts by weight In the same manner as in Example 1 using the above materials, treated particles were obtained. The treated particles were treated with "R-97" in the same manner as in Example 1.
2 ”and zinc stearate were added and mixed to obtain comparative toner d. Table 1 below shows the combinations of the base particles and the resin fine particles in the above Examples and Comparative Examples.

[Test 1] Evaluation of low temperature fixability Each of the toners A to E of the present invention and the toners a to d for comparison, and an average particle formed by coating the surface of a copper-zinc ferrite core material with a silicone resin Carrier with a diameter of 80 μm (manufactured by Powder Tech Co., Ltd.) at room temperature and normal humidity (20 ° C, 60%)
RH) and YGG (manufactured by Yayoi) for 20 minutes to prepare a two-component developer having a toner concentration of 4% by weight. Using these two-component developers, positively charged organic photoconductive photoreceptors,
An electrophotographic copying machine "U-Bix1550MR" (Konica Corp.) equipped with a developing device for a two-component developer and a heat roller fixing device and modified so that the set temperature of the heat roller can be variably adjusted.
With a modified machine, the linear velocity of the heat roller was set to 139 mm / sec, and the temperature of the backup roller was kept lower than the temperature of the heat roller.
A test for forming a fixed toner image was conducted while gradually changing the temperature within the range of 00/240 ° C.

After rubbing the front end of the obtained fixed toner image with respect to the image advancing direction with a constant load using a rubbing tester, the residual rate of the fixed toner image at the end is measured with a microdensitometer. The low-temperature fixability was evaluated by measuring and determining the minimum value of the set temperature of the heat roller (fixing minimum set temperature) when the residual rate was 80% or more. The heat roller fixing device used in this test was a heat roller having a surface layer of PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer) and having a diameter of 30 mm, and a backup roller made of silicone rubber having a surface layer coated with PFA. With a linear pressure of 0.8 kg / c
m, nip width 4.3 mm, without a mechanism for applying a release agent such as silicone oil.

[Test 2] Evaluation of Releasability In the same manner as in Test 1, a so-called solid black document was used to perform a test for forming a fixed toner image by changing the set temperature of the heat roller. The obtained fixed toner image was visually observed to check whether or not the mark of the separating claw of the fixing device remained on the solid black portion.

[Test 3] Evaluation of offset resistance A fixed toner image was formed in the same manner as in Test 1 except that the backup roller was kept at a temperature close to the set temperature of the heat roller. Under the same conditions, send the transfer paper to the heat roller fixing device and visually observe whether or not toner stains occur on it at each set temperature of the heat roller. The set temperature (offset generation temperature) was calculated.

[Test 4] Evaluation of electrification property The triboelectric charge amount of the two-component developer prepared in Test 1 was set to 350.
It measured by the blow-off method through the stainless mesh of a mesh. The blow pressure was 0.2 kg / cm ² , and the blow time was 3 sec. Further, a toner to which silica fine particles and zinc stearate were not added (silica untreated toner) was similarly mixed with a carrier, and the charge amount was measured.

[Test 5] Evaluation of fluidity The static bulk densities of the silica-untreated toner and the silica-treated toner were measured with a Kawakita-type bulk density measuring device.

[Test 6] Evaluation of Durability The image forming apparatus as shown in FIG. 2 having the developing mechanism shown in FIG. 3 and the recycling mechanism shown in FIG. 4 was used at room temperature and normal humidity (20 ° C., 60% RH). The following evaluation was performed in addition to the visual evaluation of the obtained images after 100,000 times of actual shooting tests. (A) Toner charge amount The toner charge amount was measured in the same manner as in Test 4. (B) Carrier Contamination Degree A carrier is used to separate only the carrier from the developer. 3 g of the carrier is put in 100 ml of methyl ethyl ketone to dissolve the coating resin, and the solution is 500 nm.
Was measured by a spectrophotometer “330 Hitachi Autograph Spectrophotometer”, and the value was defined as a carrier contamination degree.

The development conditions are as follows:
The set temperature of the fixing roller is 150 ° C. Latent image carrier: Positively charged organic photoconductive photoconductor Maximum potential 680V Peripheral speed 240mm / sec Outer diameter 100mm Developing device Gap between developer carrier and latent image carrier 500μ
m Gap between developer carrier and spike control plate 450μ
m DC bias voltage applied to developer carrier 150 V Peripheral speed of developer carrier 613 mm / sec Outer diameter of developer carrier 40 mm The results of the tests above are shown in Tables 2 and 3 below.

[0080]

[Table 1]

[0081]

[Table 2]

[0082]

[Table 3]

From Table 2 and Table 3, the toners A to A of the present invention are shown.
E has good low-temperature fixability, releasability, and offset resistance,
It has a sufficiently wide proper fixing temperature range. Furthermore, since it has an appropriate negative chargeability and sufficient fluidity without the addition of silica fine particles, even if silica is embedded in the toner in an image forming apparatus adopting a toner recycling system, it shows negative chargeability and fluidity. There is no significant decrease in sex. Therefore, the toner charge amount changes stably up to 100,000 times, and a good image with high image density without fog can be obtained. Further, since the fluorine-containing resin fine particles having a small surface energy are fixed on the toner surface, the toner spent on the carrier is reduced, and the developer life is also improved from this point. Further, filming on the photoconductor or the developing sleeve was not recognized at all.

On the other hand, in the toner a for comparison, the charge amount and the fluidity of the untreated silica toner are low, so the charge amount gradually decreases in the actual copying test, and fog is often generated after 30,000 times and the image density The image was low and unclear, and the toner was also scattered. Further, the comparative toner b has a low temperature fixability,
Since the releasability was poor and the toner charge amount was too high, only an image having a low image density was obtained. Further, the toner c for comparison has a very low charge amount of the silica-untreated toner, so the charge amount sharply decreases in the actual shooting test, and after 10,000 times, the image becomes unclear with a large amount of fog and a low image density. The test was discontinued after 30,000 times because it was also scattered. Also, there were many toner spent on the carrier. Further, the comparative toner d has a releasing property, an offset resistance,
The low-temperature fixability was inferior, and after 15,000 times, image stains due to stains on the fixing roller occurred. In addition, noticeable marks of the separating claws of the fixing device were generated on the solid black image.

[0085]

According to the negatively chargeable toner of the present invention, fixing can be carried out at a low temperature, filming resistance can be improved, and proper negative chargeability can be imparted to a silica-untreated toner. Therefore, the fluidity of the untreated silica toner can be improved, and the toner spent on the carrier can be reduced. An image forming method of the present invention is to provide an image forming method capable of obtaining an image with good image quality when a toner recycling system is adopted.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an example of a hybridizer that can be used for producing the negatively chargeable toner of the present invention.

FIG. 2 is an explanatory diagram showing an example of an image forming apparatus that can be used in the image forming method of the present invention.

FIG. 3 is an explanatory diagram of a developing device that can be used in the image forming method of the present invention.

FIG. 4 is an explanatory diagram of a toner recycling device that can be used in the image forming method of the present invention.

[Explanation of symbols]

1 powder feeding valve 2 powder feeding chute 3 circulating circuit 4 casing 5 rotating plate 6 blade 7 stator 8 cooling or heating jacket 9 powder discharging chute 10 powder discharging valve 20 latent image carrier 21 belt electrode 22 developing mechanism 23 Transfer Separation Electrode 24 Cleaning Mechanism 25 Static Elimination Lamp 26 Paper Feeding Mechanism 27 Conveying Mechanism 28 Fixing Mechanism 29 Recycling Mechanism 31 Developer Conveying Carrier 32 Main Stirring Roller 33 Auxiliary Stirring Roller 34 Toner Conveying Screw 35 Spike Limiting Plate 36 Doctor Blade 41 Magnetic Brush mechanism 42 Toner receiving and distributing mechanism 43 Screw conveyor 44 First screw 45 ... Second screw

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical indication location G03G 9/08 372 381 (72) Inventor Tatsuya Nagase 2970 Ishikawacho, Hachioji, Tokyo Konica Stock Company (72) Inventor Shinichi Nakamura 2970 Ishikawa-cho, Hachioji, Tokyo Konica stock company (72) Inventor Yuriko 2970 Ishikawa-cho, Hachioji, Tokyo Konica stock company

Claims (2)

[Claims] 1. A matrix particle containing a resin, in which a crystalline polyester and an amorphous vinyl polymer are chemically bonded, as a binder, has a softening point higher than the softening point of the binder resin and 160 ° C. or less. The negatively chargeable toner is characterized in that resin fine particles containing more than 30% by weight of fluorinated alkyl (meth) acrylate are fixed by mechanical impact force. 2. An image forming method employing a recycling system for reusing toner, wherein the negatively chargeable toner according to claim 1 is used.