JPH04100055A - Image forming method - Google Patents

Abstract

PURPOSE:To enhance low-temp. fixability, stress resistance and powder consistency by using a toner formed by fixing resin fine particles to base material particles consisting of a specific copolymer. CONSTITUTION:The toner which develops electrostatic charge images is recycled in this image forming method. The toner formed by fixing the resin fine particles (C) smaller than the base material particles consisting of the copolymer formed by block copolymn. and/or graft polymn. of crystalline polyester (A) and noncrystalline polyester (B) with these base material particles by mechanical impact force is used. Polyhexamethylene sebagate, etc., are used as the component A, a copolymer consisting of styrene, butyl acrylate, butyl methacrylate and acrylic acid, etc., are used as the component B. A copolymer consisting of styrene and methyl methacrylate, etc., are used as the component C.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an image forming method applied to electrophotography, electrostatic recording, electrostatic printing, etc., and further relates to the development of an electrostatic image in the method. The present invention relates to an image forming method incorporating a developer toner recycling system.

[Background of the invention]

2. Description of the Related Art As a method for forming a visible image from image information, methods using electrostatic latent images, such as electrophotography, electrostatic recording, and electrostatic printing, are widely used.

For example, in electrophotography, a latent image carrier having a photosensitive layer made of a photoconductive material is given an electrostatic charge of -, and then imagewise exposure causes the surface of the latent image carrier to have a surface corresponding to the original. An electrostatic latent image is formed, and this 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, pressure, etc. to form a copy image. On the other hand, after the transfer process, the latent image carrier is neutralized, residual toner on the latent image carrier is cleaned, and the next copy image is formed.

With the spread of these copying methods, image forming methods employing a so-called toner recycling system in which toner is collected through cleaning and reused are attracting attention in order to reduce toner running costs.

The developer toner used in the recycling system needs to be able to withstand repeated pressing force, shearing force, frictional force, or environmental influences, and maintain normal toner characteristics.

On the other hand, in recent years, due to the demand for high-speed copying machines and miniaturization of copying machines, there has been a strong desire to develop toners that can be fixed at lower temperatures than before. That is, in a high-speed copying machine, when a large number of sheets are continuously copied, the heat of the heat roller is absorbed by the transfer paper, and the heat cannot be refilled in time. As a result, the temperature of the heat roller decreases, which tends to cause fixing failure. In addition, for small-sized copying machines, it is necessary to make the copying machine compact with a small heater capacity for heating the heat roller, or if the capacity of the heater is small, it takes time to heat the heat roller and it does not open during standby. If the length becomes too long or if continuous copying is performed, heat supply cannot be done in time, and as a result, the temperature of the heat roller decreases, resulting in poor fixing.

On the other hand, when a heat roller fixing method is adopted, the toner comes into contact with the surface of the heat roller in a molten state during fixing, but if the viscoelasticity of the molten toner is too small or too large, part of the molten toner may A so-called offset phenomenon occurs in which the toner transfers and adheres to the surface of the heat roller and transfers again to the next transferred transfer paper, staining the image. This offset phenomenon includes under-offset, which occurs when the toner is underheated, and hot offset, which occurs when the toner is overheated.As for toner, there is a minimum fixing temperature at which it can be fixed, and a hot offset phenomenon occurs. It is preferable that the applicable temperature range for fixing is wide.

On the other hand, in order to form images of good quality, it is necessary that the toner has high fluidity. As a technique for improving the fluidity of toner, it is known to add a fluidizing agent such as silica particles to toner components.

However, when a toner recycling system is used to form an image using a toner containing a fluidizing agent such as silica fine particles, the toner is frequently subjected to mechanical stress due to recycling. Fine particles are embedded in the toner particles and the fluidity of the toner gradually decreases, resulting in a slow build-up of the toner's frictional electrification, which causes fogging on the image and smudges on the image due to poor cleaning. There is a problem.

In addition, in toner, scales exist stably as a powder without agglomerating under the environmental conditions of use or storage.
In other words, it is required to have excellent blocking resistance.

Various techniques have been proposed in response to such problems or requests.

For example, JP-A No. 63-27855, JP-A No. 63-27856
In JP-A No. 1-163755, a copolymer of crystalline polyethylene and an amorphous vinyl polymer was used in the toner, and in JP-A-1-163755, the toner was prepared by applying mechanical impact force to improve low-temperature fixability and offset resistance. However, when applied to a recycling system, silica fine particles in the fluidizing agent cause embedding of toner particles, resulting in poor toner properties. to degrade.

Furthermore, in JP-A-1-105261, fixing performance is improved by attaching fine resin particles with a high Tg to toner particles using mechanical impact force, but the resin particles come off during recycling, causing filming on the fixing roller. I start waking up.

Furthermore, in Japanese Patent Application Laid-open No. 1-234859, organic fine particles were added to toner particles to improve image quality and cleaning properties during recycling, but the toner lacked durability in long-term use.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming method that uses recycled toner that has low-temperature fixability, high stress resistance, and good powder stability.

In the present invention, stress resistance is a practical expression of viscoelasticity that does not fracture due to strain force, and powder constancy refers to the ability to contain various constituent particles in accordance with prescription standards. In toner powder, it is said that the existence form and existence density of the constituent particles remain unchanged from the new toner.

[Structure of the invention]

The object of the present invention is to provide an image forming method in which a toner used for developing an electrostatic image is recycled, which is a copolymer formed by block polymerizing and/or grafting a crystalline polyester and an amorphous vinyl polymer. To the base particle,
This is achieved by an image forming method characterized by using a toner in which fine resin particles smaller than the base particles are fixed by mechanical impact force.

[Function and effect of the invention]

As in the present invention, by using a copolymer obtained by block polymerization and/or graft polymerization of crystalline polyester and amorphous vinyl polymer as the toner base particles,
The resulting toner has good low-temperature fixability and satisfactory offset resistance.

In addition, in recycling systems, the stress resistance of the toner is increased by fixing organic fine particles to the surface of the toner base particles by mechanical impact force, and the silica particles of the fluidizing agent are not buried in the toner base particles, and the carrier The powder constancy of the silica particles is maintained without any filming of the organic particles, and there is no drop in Q/M, allowing smooth image formation for a long period of time.

Further, due to the characteristics of the toner according to the present invention described above, the image forming method of the present invention not only provides good image quality, but also has a short warm-up time and a small temperature drop in the heat roller due to fixing. This provides a high-speed and low-cost image forming method that is possible and further reduces the running cost of toner.

Furthermore, there is less damage to the image forming apparatus, especially the fixing roller and the photoreceptor, due to the fixing heating temperature, and there are also fewer thermal disasters.

Crystalline polyester is a polymer that has a crystal structure at least in part, and includes homopolymers or copolymers in which at least one component is crystalline, that is, partially crystalline, and has a sharp and distinct melting point. In the solid state at a temperature below the melting point, it becomes cloudy due to crystalline parts.

Specifically, such crystalline polyesters include, for example, polyethylene sebacate, polyethylene adipate,
Polyethylene adipate, polyethylene adipate, polyethylene p-(carbophenoquine) undecaate, polyhexamethylene succinate, polyhexamethylene sebacate, polyhexamethylene sebacate, polyhexamethylene succinate, polyhe xamethylene decanedioate, polyoctamethylene dodecanedioate,
Polynonamethylene azelate, polydecamethylene adipate, polydecamethylene azelate, polydecamethylene adipate, polydecamethylene sebacate, polydecamethylene succinate, polydecamethylene dodecanedioate, polydecamethylene octadecanedioate , polytetramethylene sebacate, polytrimethylene dodecanedioate, polytrimethylene octadecanedioate, polydecamethylene azelate, polyhexamethylene-
Decamethylene Sebacate, Polyoxydecamethylene
Examples include 2-methyl-1,3-propane-dodecanedioate.

The above-mentioned crystalline polyester is obtained by a polycondensation reaction of an alcohol monomer and a carboxylic acid monomer, and examples of the alcohol monomer include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1.3-propylene glycol,
1,4-butanediol, neopentyl glycol, 1
．． Diols such as 4-butynediol, 1,4-bis(
hydroxymethyl)isoclohexane, bisphenol A
, hydrogenated bisphenol A, polyoxyethylenated bisphenol A1, etherified bisphenol A such as polyoxypropylenated bisphenol A, sorbitol, 1.2,3.6-hexanetetrol, 1,4-sorbitan, pentaerythritol, Dipentaerythritol, tripentaerythritol, sucrose, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, triol Mention may be made of methylolethane, trimethylolpropane, 1.3.5-)lyhydroxymethylbenzene, and others.

In addition, examples of carboxylic acid monomers include maleic acid,
fumaric acid, mesaconic acid, citraconic acid, itaconic acid,
Glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, nclohexanedicarboxylic acid, succinic acid, adipic acid,
Cepatic acid, malonic acid, anhydrides or lower alkyl esters of these acids, dimer of liluic acid, other divalent organic acid monomers, 1.2.4-benzenetricarboxylic acid, 1.2.4 -Cyclohexanetricarboxylic acid, 2゜5.7-naphthalenetricarboxylic acid, 1,24-naphthalenetricarboxylic acid, 1,2.4-butanetricarboxylic acid, 1,2.5-hexanetricarboxylic acid, 1,3-dicarboxylic acid 2-methylcarboxypropene, 1,3-
Dicarboxy-2-methyl-2-methylenecarboxinpropane, tetra(methylenecarboxy)methane, 1.
Examples include 2.78-octane tetracarboxylic acid, embol trimer acid, anhydrides thereof, and others.

In crystalline polyethylene, when the melting point Tm is too low, blocking resistance deteriorates, and when the melting point Tm is too high, low-temperature fixability deteriorates.

As crystalline polyethylene, coulometric average molecular weight Mw or s
ooo ~so, ooo, number average molecular weight Mn or 200
0-20,000 is preferred.

As the amorphous vinyl polymer, a polymer or copolymer of a monomer having a vinyl group can be used. In particular, a copolymer of a styrene monomer and an acrylic ester or methacrylic ester monomer is preferred. Among them, the weight average molecular weight Mw is 40.000 or more, especially 40.000-500.000, and the number average molecular weight Mn is 2.
．． 000 or more, especially 2.000-10.000, the ratio of weight average molecular weight Mw to number average molecular weight Mn Mw/Mn
A copolymer having a value of 5.0 or more, particularly 5.0 to 50 is preferred. When such a copolymer is used, the under-offset generation temperature can be lowered and the hot-offset generation temperature can be increased, so that the applicable temperature range for fixing becomes extremely wide. Further, it is preferable that the softening point Tsp measured by an elevated flow tester is 100 to 150'C.

Examples of the styrenic monomer for obtaining the amorphous vinyl polymer include styrene, 0-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-ethylstyrene, and 24-dimethylstyrene. ,p-
Butylstyrene, pt-butylstyrene, p-hexylstyrene, p-octylstyrene, p-nonylstyrene, p-decylstyrene, p-dodecylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3 , 4-dichlorostyrene, and the like.

Examples of acrylic ester or methacrylic ester monomers for obtaining an amorphous vinyl polymer include methyl acrylate, ethyl acrylate, butyl acrylate, isobutyl acrylate, propyl acrylate, octyl acrylate, and acrylic acid. Dodecyl, lauryl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, methyl α-chloroacrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, methacrylate Examples include isobutyl methacrylate, octyl methacrylate, dodecyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, and the like.

Specific examples of copolymers made of these monomers include styrene/butyl acrylate copolymer, styrene/butyl methacrylate copolymer, styrene/butyl acrylate/methyl methacrylate copolymer, and styrene/methacrylate copolymer. Examples include acid butyl methacrylate/methyl methacrylate copolymer.

When the crystalline polyester and the amorphous vinyl polymer are used as the resins of the toner base particles, it is preferable that the crystalline polyester and the amorphous vinyl polymer are substantially incompatible.

Note that "substantially incompatible" means that the crystalline polyester and the amorphous vinyl polymer are not sufficiently dispersed, and specifically, for example, the S, P, values (R,
F, Fedors, Polym, I! ng,
Sci.

14, (2) 147 (1974)) is greater than 0.5.

When a block copolymer or a graft copolymer is obtained from a crystalline polyester and an amorphous vinyl polymer, the functional groups of the amorphous vinyl polymer include, for example, a carboxyl group, a hydroxyl group, an amino group, and an epoxy group. is preferred. Examples of monomers having such functional groups include acrylic acid, ββ-dimethylacrylic acid, α-ethyl acrylic acid, methacrylic acid, fumaric acid, itaconic acid, maleic acid, crotonic acid, hydroxyethyl methacrylate,
Examples include acryloyloxyethyl monosuccinate, N-hydroxyethyl acrylamide, N-methylolacrylamide, p-aminostyrene, glycidyl methacrylate, and the like.

A monomer having such a functional group is contained in a monomer composition for obtaining an amorphous vinyl polymer in an amount of 0.1 to 20 mol%.
, preferably in a proportion of 05 to 10 mol %.

The vinyl polymer that constitutes the main portion of the amorphous vinyl polymer is not particularly limited, and examples include polystyrene, polymethyl methacrylate, polymethyl acrylate, polyvinyl chloride, polyvinyl acetate, polyacrylonitrile, and the like. Copolymers and the like can be mentioned. In particular, styrene polymers, acrylic polymers, and styrene/acrylic copolymers are preferred, and the styrene monomers or acrylic monomers used to form such polymers include the amorphous monomers mentioned above. Examples of monomers for the vinyl polymer include those exemplified above.

The amorphous vinyl polymer has a ratio Mw/Mn of the weight average molecular weight Mw to the number average molecular weight Mn of 3.5 or more,
In particular, it is preferable that it is 5.0 or more. Further, it is preferable that the weight average molecular weight Mw is 10.000 or more, and the number average molecular weight Mn is 2.000 or more. Such molecular weight distribution measurements can be performed by gel permutation chromatography (GPC).

When such an amorphous vinyl polymer is used, the under-offset generation temperature can be lowered and the hot-offset generation temperature can be increased, so that the applicable temperature range for fixing becomes extremely wide. In addition, the amorphous vinyl polymer has a softening point Tsp of 100 to 150 using an elevated flow tester.
°C is preferred.

The glass transition point Tg of the amorphous vinyl polymer is 50 to 10
0°C, especially 50 to 85°C is preferred. When the glass transition point Tg is too low, blocking resistance tends to deteriorate, and when it is too high, fixing ability tends to deteriorate.

Further, when obtaining a block copolymer or a graft copolymer, the proportion of the crystalline polyester is preferably 3 to 50 wt%, particularly 5 to 40 wt% of the resulting copolymer. When the proportion of crystalline polyester is too small, low-temperature fixing properties tend to deteriorate, while when it is too large, anti-offset properties tend to deteriorate.

In order to obtain a block copolymer or a graft copolymer with a crystalline polyester and an amorphous vinyl polymer, they can be directly attached to each other in a head-to-tail manner, for example by a coupling reaction between the terminal functional groups present in the various polymers. Can be combined. Alternatively, each terminal functional group can be bonded with a bifunctional coupling agent, for example, a urethane bond formed by the reaction of a diisocyanate with a polymer whose terminal group is a hydroxyl group; Ester bonds formed by the reaction of a certain polymer with a dicarboxylic acid or the reaction of a polymer with a carboxyl terminal group with a glycol, and the reaction of a polymer with a terminal group with a droxyl group with phosgene or dichlorodimethylsilane. They can be bonded by other bonds such as those formed by.

Such coupling agents include, for example, difunctional isocyanates such as hexamethylene diisocyanate, diphenylmethane diisocyanate, toridine diisocyanate, toridine diisocyanate, naphthylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, etc., such as ethylene diamine, hexamethylene diamine, phenylene diamine, etc. Difunctional amine:
Difunctional carboxylic acids such as oxalic acid, succinic acid, adipic acid, sebacic acid, terephthalic acid, isophthalic acid; such as ethylene glycol, propylene glycol, butanediol, benzanediol, hexanediol, cyclohexane dimetatool, p-xylylene Difunctional alcohols such as glycols; difunctional acid chlorides such as terephthalic chloride, isophthalic chloride, adipic chloride, sebacic chloride; other difunctional acids such as diisothiocyanates, bisketenes, biscarbodiimides, etc. Coupling agents and the like can be mentioned. The coupling agent is used in an amount of 1 to 10 w[%, particularly 2 to 7 wt], based on the total amount of the crystalline polyester and the amorphous vinyl polymer.
It is preferable to use the proportion of %. When the proportion of the coupling agent is too large, the softening point of the obtained block copolymer or graft copolymer becomes too high, which tends to deteriorate low-temperature fixing properties, and on the other hand, when the proportion of the coupling agent is too small, the anti-offset properties tend to deteriorate.

In the above, melting point Tm refers to differential scanning calorimetry (D
SC), 10 mg of sample was heated at a constant heating rate (10°
It refers to the melting peak value when heated at C/win). The glass transition point Tg is determined by heating sample 10B at a constant heating rate (10"C/m1n) according to differential scanning calorimetry (DSC).
) is the value determined from the intersection of the baseline and the slope of the endothermic peak.

In addition, the weight average molecular weight Mw and the number average molecular weight Mn are
Gel vermucation chromatography (GPC)
) was measured as follows. That is, at a temperature of 40°C, a solvent (such as tetrahydrofuran) is flowed at a flow rate of 1.2-min/min, and the concentration is 0.2g/20-min.
Measurements are made by injecting 3 cm of tetrahydrofuran sample solution as the sample weight. When measuring the molecular weight of a sample, select measurement conditions in which the molecular weight of the sample falls within a range where the logarithm of the molecular weight and the count number of a calibration curve created using several types of monodispersed polystyrene standard samples are linear.

The reliability of the measurement results is based on NB57 conducted under the above measurement conditions.
This can be confirmed by observing that the weight average molecular weight Mw 28.8X 10' and the number average molecular weight Mn 13.7X 10'' of the 06 boristyrene standard sample are used as a GPC column as long as it satisfies the above conditions. Any material may be used; for example, TSK-GEL, GM) (manufactured by Toyo Soda Co., Ltd.), etc. can be used.

Note that the solvent and measurement temperature are not limited to those mentioned above and may be changed as appropriate.

The resin of the resin particles fixed to the surface of the toner base resin particles in the first stage has a glass transition point Tg of 50° C. or higher. When the glass transition point Tg is too small, blocking resistance deteriorates.

The resin used for the resin fine particles has a glass transition point T
It is preferable that g is 50°C or more, and specifically, vinyl polymers or copolymers, polyesters, epoxy resins, polyurethanes, polyamides, polyureas, fluororesins, etc. can be used.

The resin constituting the fine resin particles is preferably a vinyl polymer because it is relatively hard and can sufficiently improve fluidity and cleaning properties. Such vinyl polymers can be produced by various polymerization methods such as emulsion polymerization and suspension polymerization, but emulsion polymerization is preferred because small-diameter, spherical resin particles can be efficiently obtained. In particular, in systems where the monomer itself for obtaining the vinyl polymer has an emulsifying effect, it is preferable to obtain the vinyl polymer by emulsion polymerization without using an emulsifier.

Examples of vinyl polymers include acrylic polymers, styrene polymers, vinyl group-containing fluororesins, and the like. Among these, acrylic polymers are particularly preferred. That is, the fine resin particles made of an acrylic polymer exhibit an excellent cleaning performance improvement effect.

Such acrylic polymers are homopolymers or copolymers obtained by polymerizing monomers selected from acrylic acid, acrylic esters, methacrylic acid, and methacrylic esters.

The softening point of the resin fine particles is 300°C or less, especially 100 to 2
00°C is preferred. If the softening point is too high, it will be difficult to fix the toner to the surface without agglomerating the toner.

The average particle size of such fine resin powder is small (necessarily smaller than the average particle size of the toner base particles, 1 μm or less, especially 0.0 μm or less).
The thickness is preferably about 2 to 0.6 μm. When the average particle size is too large, it becomes difficult to adhere to the toner surface.

Furthermore, if it is extremely small, it is likely to be embedded in the toner surface, resulting in a decrease in blocking resistance.

The resin fine particles preferably account for 0.01 to 3.0 wt%, particularly preferably 0.1 to 2.0 wt%, based on the entire toner. If the proportion of the resin fine particles is too small, the fluidity of the toner tends to decrease and poor cleaning tends to occur. On the other hand, if it is too large, the toner friction #Ft is likely to be inhibited.

Other toner components used together with the binder resin include a variety of additives such as colorants, charge control agents, flow agents, and lubricants, which can be used as necessary.

Examples of colorants include carbon black, nigrosine dye, aniline blue, calco oil blue, chrome yellow, ultramarine blue, pont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green offsalate, lamp blank, rose bengal, mixtures thereof, Others can be used.

Examples of the charge control agent include nigrosine dyes, metal-containing azo dyes, and metal complexes.

In order to further improve the viscoelasticity of the toner when it is melted,
Or, to further improve fixing properties, melting point is 50
It is preferable to knead and use wax at a temperature of about 150° C. with a binder resin. Specifically, liquid or solid paraffin, low molecular weight polyolefins such as polyethylene or polypropylene, fatty acid metal salts, fatty acid esters, partially saponified fatty acid esters, higher fatty acids, higher alcohols, silicone resin, amide waxes,
Aliphatic fluorocarbons and modified products thereof can be used.

Examples of the fluidizing agent include silica, alumina, titania, barium titanate, cerium titanate, calcium titanate, strontium titanate, zinc oxide, silica sand,
Examples include fine particles of clay, mica, wollastonite, diatomaceous earth, chromium oxide, cerium oxide, hengara, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, silicon nitride, and the like. Particularly preferred are silica particles.

As the silica, generally known colloidal silica can be used, and those that have been hydrophobized are particularly preferred. Specific examples of colloidal silica particles include "Aerosil 200", "Aerosil 300J", and rAerosil 130J (manufactured by Nippon Aerosil Co., Ltd.).
“Aerosil R-972J,” “Aerosil R-812J
, "Aerosil R-805J (manufactured by Nippon Aerosil Co., Ltd.), etc."

The primary particle diameter of these fluidizing agents is preferably 5 to 2 μm, particularly 5 to 500 μm. The addition and mixing ratio of the fluidizing agent is preferably, for example, 0.01 to 5 wt%, particularly 0.05 to 2 wL%, based on the total toner.

Examples of the lubricant include zinc stearate, lithium stearate, sodium stearate, stearic acid, hydrogenated castor oil, and others. The addition/mixing ratio of these lubricants is, for example, 0.01 to 2.0% of the total toner.
wt% is preferred.

The toner according to the present invention may be used as a two-component developer by being mixed with a carrier, or may be used as a one-component developer without being mixed with a carrier.

When the toner is used as a one-component developer, the toner usually contains fine magnetic particles. Such magnetic fine particles include, for example, ferromagnetic metals such as iron, nickel, and cobalt, alloys containing these metals, compounds of ferromagnetic metals such as ferrite and magnetite, and materials that do not contain ferromagnetic elements but are appropriately heat-treated. Alloys that exhibit ferromagnetic properties, such as manganese-copper-aluminum, manganese-copper-
Examples include alloys of a type called Heusler alloys such as tin, or fine particles such as chromium dioxide.

The average particle size of the magnetic fine particles is preferably 0.1 to 1 μm. Further, the amount of magnetic fine particles added is usually 20 to 70 wt% of the toner raw material.

To give an example of a preferred method for producing the toner according to the present invention, first, a copolymer resin obtained by block polymerization and/or graft polymerization is crushed and classified, and a copolymer resin powder having a particle size desirable for the toner is produced. Get a body. The particles of the copolymer resin powder may contain toner components as described above. Next, fine resin particles are added to the copolymer resin powder and stirred using, for example, a type mixer, so that the fine resin particles are electrostatically attached to the surface of the particles of the copolymer resin powder. This is placed in an impact-type pulverizer and subjected to impact. By processing in this way,
Resin fine particles can be fixed to the surface of the base particles.

In the present invention, the term tf!J in which fine resin particles are "fixed" to the surface of the base particles of the copolymer resin powder refers to the height of the part of the fine resin particles exposed from the surface of the base particles of the copolymer resin powder. This refers to a state in which the diameter is 10 to 90% of the diameter of the inverted resin fine particles. Such a state can be easily confirmed by observing the surface of the toner particle using a transmission electron microscope or a normal electron microscope.

In order to obtain such a state, in a system where copolymer resin powder and resin fine particle powder coexist, an impact force of a magnitude that does not crush the copolymer resin powder base particles, such as that normally required for pulverization, is required. An impact force that is 115 to 1/10 of the force required to be applied may be applied.

Specifically, it varies depending on the characteristics of the copolymer resin, but
1.59X10-1 per copolymer resin powder particle
-9.56x to-erg, preferably 1.20x
An impact force of 10-'-1, 60×10” erg may be applied.

Further, the time period during which the impact force is applied is selected based on the hardness of the copolymer resin, the operating conditions of the pulverizer used, and the like.

In the present invention, 5% of the total base particles of the copolymer resin powder
It is preferable that the resin fine particles are fixed to 0% or more of the particles, and the surface area of the base particles is 10 to 9% of the surface area of the base particles.
It is preferable that 0% of the area is covered with fixed resin particles.

If it is less than 10%, the blocking resistance will not be sufficiently exhibited,
If it exceeds 90%, fixing properties and anti-offset properties will deteriorate.

Although it is difficult to clearly confirm to what extent the surface of the copolymer resin powder base particles is actually covered with resin fine particles, the theoretical coverage rate is expressed by the following formula.

ρ, (100-C)D.

ρl: Specific gravity ρ2 of copolymer resin base particles. Specific gravity of resin fine particles 1. Particle size of copolymer resin base particles: Particle size C of resin fine particles・Concentration of resin fine particle powder (%) Specific treatment for fixing resin fine particles to the surface of the base particles of copolymer resin powder The method is not particularly limited, and the process may be performed multiple times.

Next, each step of the image forming method of the present invention will be specifically explained.

(Developing process) A one-component developer or a two-component developer composed of a toner having fixed resin particles as an essential component is conveyed to a developing area by a developer conveying carrier, and this developer is used to develop images on a latent image carrier. The electrostatic latent image is developed to form an unfixed toner image. The developing method is not particularly limited, and conventionally known methods can be applied. Specifically, the following methods can be mentioned.

■ A magnetic brush of developer with higher spikes than the gap in the developing area is formed on the developer transporting carrier, and this magnetic brush is conveyed to the developing area, and the electrostatic latent image is formed on the latent image carrier by the magnetic brush. A contact magnetic brush development method in which the toner in a magnetic brush adheres to the electrostatic latent image while rubbing.

■A magnetic brush of developer with lower spikes than the gap in the development area is formed on the developer transport carrier, and this magnetic brush is conveyed to the development area, and an oscillating electric field is applied to the development area to create a magnetic plano. A jumping magnetic brush development method that develops by causing toner to fly and adhere to the electrostatic latent image.

■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 a static transfer method or a bias transfer method can be applied, but an electrostatic transfer method is particularly preferred. Specifically, for example, a transfer device that directly generates corona discharge is placed so as to face the latent image carrier through the recording material, and the latent image is carried by applying direct current corona discharge to the recording material from the back side. The unfixed toner image carried on the surface of the body is transferred to the surface of the recording material.

(Cleaning step) Toner remaining on the latent image carrier after the transfer step is cleaned. The cleaning means is not particularly limited, but a cleaning device having a cleaning blade disposed in contact with the surface of the latent image carrier is preferable. According to this cleaning device, residual toner is scraped off by rubbing the surface of the latent image carrier with the cleaning blade.

In order to facilitate cleaning, it is preferable to add a static elimination process to neutralize the surface of the latent image carrier before the cleaning process.

This static elimination step can be performed, for example, using a static eliminator that generates AC corona discharge.

(Recycling Step) The toner collected by cleaning is returned to the developing device through an appropriate recycling system and reused.

FIG. 1 is an explanatory diagram showing an example of a recycling system. Reference numeral 20 denotes a recovery drum, and the recovery drum 20 is coaxially supported on the negative end side of a drum-shaped latent image carrier (not shown) via a partition wall (not shown). A plurality of magnets 21 are fixedly provided inside the collecting drum 20 along its outer periphery, and a conveyor belt 22 is suspended around the outer periphery of the collecting drum 20.

23 is a cleaning mechanism, and this cleaning mechanism 23 extends so as to face the cleaning area of the latent image carrier and also to face the collection drum 20.

In this cleaning mechanism 23, the toner remaining on the latent image carrier is scraped off and collected by, for example, a blade, and the collected toner is supplied to the output O25 side by a screw conveyor 24 provided inside. be done.

26 is a developing mechanism, and this developing mechanism 26 includes a rotating drum-shaped magnetic brush mechanism 27 arranged to face the developing area of the latent image carrier and also face the collection drum 20;
It has a developer stirring mechanism 28 and a toner receiving and distributing mechanism 29 that receives the collected toner and distributes it into the developing mechanism 26, and the conveyor belt 22 has a collecting drum 20 and a magnetic brush mechanism. After passing through the gap between the toner collecting drum 20 and the outlet 27 of the cleaning mechanism 23, the toner is transferred to the toner receiving and distributing mechanism 29 of the developing mechanism 26 via the gap between the collecting drum 20 and the outlet 25 of the cleaning mechanism 23.
It is suspended between the collecting drum 20 and rollers 30 and 31 so as to reach this point. 27a is a rotating sleeve, and 27b is a magnet.

In this example, when the conveyor belt 22 is moved, the conveyor heald 22 or the collecting drum 20 and the magnetic plano mechanism 27
When the developer passes through the gap, a magnetic brush of the developer is formed on the conveyor belt 22 by the magnetic plan mechanism 27,
When this magnetic brush is transferred to the cleaning mechanism 23 as the conveyor belt 22 moves, the cleaning mechanism 23
The toner collected from the latent image carrier by the screw conveyor 24 and supplied to the exit 25 side is picked up by the magnetic plan on the conveyor belt 22, and as the conveyor belt 22 moves, the toner picked up by the magnetic brush is The toner is conveyed to the toner receiving and distributing mechanism 29, where the toner is stored in the developing mechanism 26, and the collected toner is again used to develop the latent image on the latent image carrier.

FIG. 2 is an explanatory diagram showing another example of the recycling system. 41 is a developing mechanism, 42 is a cleaning mechanism, 43 is a toner receiving and distributing mechanism, 44 is a magnetic brush mechanism, 45 is a latent image carrier, 46 is a screw conveyor, 47 is a first screw, and 48 is a second screw. In the example device, a first screw 47 and a second screw 48 supply toner from a screw conveyor 46 to a toner receiving and distributing mechanism 43. That is, the first screw 47 and the second screw 48 each have a rotating shaft inside and a blade spirally provided along the rotating shaft. As the rotary shaft rotates, the toner is sequentially pushed up by the blades and sent to the second screw 48. In the second screw 48, the toner is sequentially sent in the horizontal direction using the same principle as the first screw 47. The collected toner is supplied to the toner receiving and distributing mechanism 43 and used again to develop the latent image on the latent image carrier 45 .

(Fixing Step) The recording material onto which the unfixed toner image has been transferred in the transfer step is subjected to a fixing process using a heat fixing device, a pressure fixing device, or the like to form a fixed toner image on the recording material.

〔Example〕

Examples of the present invention will be described below along with comparative examples, but the present invention is not limited to these embodiments. In addition, in the following, "part" represents "part by weight".

<Crystalline polyester 1> 1500 g (7.41 mol) of sebacic acid and 964 g (8.16 mol) of hexamethylene glycol were added to a thermometer, a stainless steel stirrer, a glass nitrogen gas inlet tube, and a submerged condenser. The flask was then placed in a mantle heater, and nitrogen gas was introduced through a glass nitrogen inlet tube to raise the temperature while maintaining an inert atmosphere inside the reactor. . Then, 13.2 g of p-+-luenesulfonic acid was added and reacted at a temperature of 150°C.

The amount of water flowing out due to the esterification reaction was 2501nl.
The reaction was stopped when the temperature was reached, and the reactant was taken out. This was cooled to room temperature to obtain a crystalline polyester 1 made of polyhexamethylene sebacate having a hydroxyl group at the end of the molecule. The melting point Tm of this crystalline polyester 1 is 64
It was °C. However, the melting point Tm is determined by differential scanning calorimeter r
This is a value measured using Dsc-20J (manufactured by Seiko Electronics Industries, Ltd.). Moreover, the weight average molecular weight Mw of the crystalline polyester 1 was 12.300.

<Crystalline polyester 2> Tm=
Crystalline polyester 2 made of polyethylene sebacate at 70° C. and Mw=11,000 was obtained.

Amorphous vinyl polymer l> Put 100 parts of toluene in a separable flask with a capacity of 11, add 7.5 parts of styrene, 2.5 parts of butyl acrylate, and 01 part of benzoyl peroxide, After replacing the gas phase in the flask with nitrogen gas, the temperature was increased to 80°C.
The temperature was raised to °C and maintained at this temperature for 15 hours to carry out the first stage polymerization.

Thereafter, the inside of the flask was cooled to a temperature of 40°C, and 85 parts of styrene, 10 parts of butyl methacrylate, 5 parts of acrylic acid, and 4 parts of benzoyl peroxide were added thereto. After continuing stirring for 2 hours, the temperature was raised again to 80°C and maintained at that temperature for 8 hours to perform second stage polymerization.

Next, add 0 zinc oxide, which is a polyvalent metal compound, to the flask.
．． 5 g was added, and the reaction was carried out for 2 hours while maintaining the temperature at reflux and stirring.

Thereafter, toluene was distilled off using an aspirator and a vacuum pump, and the mixture was dried to produce an amorphous vinyl polymer 1 in which the carboxyl groups of the vinyl polymer were reacted with zinc oxide to form ionic crosslinks. Note that this amorphous vinyl polymer 1 has a carboxyl group as a functional group for bonding with the crystalline polyester.

This amorphous vinyl polymer 1 has two peaks in its molecular weight distribution by GPC, the peak molecular weight on the high molecular weight side is 251.200, and the peak molecular weight on the low molecular weight side is 4.
It is 000. In addition, the weight average molecular weight Mw is 93200
, Mw/Mn value is 18.4, glass transition point Tg is 60
The °C1 softening point Tsp is 128°C.

<Amorphous vinyl polymer 2> Styrene 85 parts Butyl methacrylate 10 parts Acryloyl oxinoethyl monosacnate 5 parts Benzoyl peroxide 4 parts A monomer mixture having the above composition was added to a volume of 1 containing 100 parts of toluene.
After the gas phase in the flask was replaced with nitrogen gas, the temperature was raised to 80"C and kept at this temperature for 15 hours to carry out polymerization. Thereafter,
Amorphous vinyl polymer 2, which is a styrene-acrylic resin having carboxyl groups, was obtained by distilling off toluene using an aspirator and a vacuum pump. This amorphous vinyl polymer 2 has one peak in the molecular weight distribution by GPC, and the peak molecular weight is 65,000.
Met. Further, Mw was 71.000, Mw/Mn value was 7.5, Tg was 67'' and C5Tsp was 123°C.

Copolymer A> Crystalline polyester 1 225g (15 parts) Amorphous vinyl polymer 1 1275g (85 parts) p
-Toluenesulfonic acid 0.75g (0.05 parts)
The above materials were placed in a 51 volume separable flask containing 1.51 g of xylene, and the temperature was raised while nitrogen gas was introduced to maintain an inert atmosphere inside the reactor. The crystalline polyester and the amorphous vinyl polymer were completely dissolved in xylene, and then refluxed at a temperature of 150°C for 1 hour. Next, the kiln was distilled off using an aspirator and a vacuum pump, and then the reactant was taken out and cooled to room temperature to obtain a copolymer.

Copolymer B> Crystalline Polyester 2 225g (15 parts) Amorphous Vinyl Polymer 2 1275g (85 parts) Copolymer B was obtained in the same manner as Copolymer A using the above materials.

<Material particle A> Copolymer A 100 parts Carbon black 10 parts Paraffin wax 3 parts Alkylene bis fatty acid amide Put 3 parts or more of the materials into a V-type mixer,
Mixed for 20 minutes, melt-kneaded using a twin-screw extruder, cooled, and coarsely ground using a Wiley mill to obtain a 2-mm pass product, further finely ground using a supersonic jet mill, and then using an air classifier to produce fine particles with a particle size of 5 μm or less. The powder was removed to obtain base particles A having an average particle size of 11 μm.

<Base Particle B> Base Particle B was obtained in the same manner except that Copolymer A was changed to Copolymer B in the production of the base particle.

<Comparative base particles a> Comparative base particles a were produced in the same manner except that in the production of base particles A, the copolymer was changed to amorphous vinyl polymer l.
I got it.

<Resin fine particles A> Using potassium persulfate and sodium thiosulfate as initiators, 75 parts of styrene and 25 parts of methyl methacrylate were polymerized to obtain resin fine particles A consisting only of resin and having an average particle size of 0.4 μm. .

Toner A> Add 5 parts of resin fine particles A to 95 parts of the base particles,
This was sufficiently stirred and mixed using a V-type mixer to electrostatically adhere the resin particles A to the base particles A. Next, these were put into an impact-type crusher "Nara Hybridization System NH3-I J (Nara Machinery Manufacturing Co., Ltd.), and mechanical impact force was repeatedly applied for 5 minutes with the impact blades rotating at 6000 rpm. Then, fine resin particles A were fixed to the surfaces of base particles A to obtain treated particles A.

When the surface of the treated particles A was observed using a scanning electron microscope, it was found that the resin particles A, which had been electrostatically attached to the surface of the colored base particles A, were firmly fixed. Ta.

Furthermore, for 100 parts of treated particles A, 0.0 parts of silica fine particles whose surfaces were treated with polysiloxane ammonium salt were added.
8 parts and 0.1 part of zinc stearate were added, and these were
Toner A was obtained by mixing using a mold mixer.

<Toner B> 2 parts of resin fine particles A were added to 98 parts of base particles B, and these were sufficiently stirred and mixed using a V-type mixer to electrostatically adhere the resin fine particles A to base particles B. . And IN
Resin fine particles A were applied to the surface of base particles B in the same manner as toner A except that the rotational speed of the blower blade was changed to 5000 rpI11.
were fixed to obtain treated particles B.

When the surface of the treated particles B was observed using a scanning electron microscope, it was confirmed that the resin fine particles A were firmly fixed to the surface of the base particles B.

Furthermore, silica fine particles and zinc stearate are added and mixed to the treated particles B in the same manner as toner A, and toner B
I got it.

<Comparative toner a> Treated particles a were obtained by fixing resin fine particles A to the surface of comparative toner base particles a in the same manner as toner 8 except that base particles A were changed to comparative base particles a. .

When the surface of the treated particles a was observed using a scanning electron microscope, it was confirmed that the resin fine particles A were firmly fixed to the surface of the comparative base particles a.

Furthermore, fine silica particles and zinc stearate were added and mixed to the treated particles a in the same manner as toner A to obtain comparative toner a.

<Comparative Toner B> Comparative Toner b was obtained in the same manner as Toner A except that the impact type crusher "Nara Pipe Redization System NH3-IJ" was not used.

<Adjustment of developer> Each of the above toners and a carrier having an average particle diameter of 80 μm, which is made of magnetic particles made of copper-zinc ferrite (manufactured by Nippon Tetsuko Kogyo Co., Ltd.) coated with styrene-methyl methacrylate copolymer resin, were used. By mixing, each two-component developer having a toner concentration of 5 wt% was prepared.

<Evaluation> (Low-temperature fixability of toner) An electronic system equipped with a latent image carrier made of a selenium photoconductor, a developing device for a two-component developer, and a heating roller fixing device, and modified so that the set temperature of the heating roller can be variably adjusted. Photocopy machine “U-
Using a modified former χ1600J (manufactured by Konica ■), the linear speed of the heating roller was set to 139 m/s, and the temperature of the heating roller was set to 100 to 240 m/s while keeping the temperature of the pressure roller lower than the set temperature of the heating roller. A photocopy test was conducted in which a fixed toner image was formed using each of the above-mentioned developers without changing the temperature stepwise within the range of °C. After rubbing, the residual rate of the image at the edge was measured using a microdensitometer, and the lowest set temperature (minimum fixing temperature) at which the residual rate was 80% or more was determined. The heating roller fixing device has a heating roller with a diameter of 30 mm and whose surface layer is made of PFA (tetrafluoroethylene/perfluoroalkyl vinyl ether copolymer), and a silicone rubber r KE-1300RTVJ whose surface layer is coated with PFA. (
(I manufactured by Etsu Kagaku Kogyo Co., Ltd.) It has a horizontal pressure roller, the linear pressure is 0.8 kg/an, the nip radius is 4.3 mm, and it is not equipped with a mechanism for dispensing release agents such as silicone oil. It is something.

(Hot offset resistance of toner) A fixed toner image was formed in the same manner as above (low temperature fixing properties of toner) except that the pressure roller was kept at a temperature close to the set temperature of the heating roller, and immediately after that, a blank paper was Under similar conditions, the recording material is sent to the heating roller fuser and visually observed to see if toner stains occur on it at each heating roller temperature setting, and the highest setting that does not cause toner stains is determined. The temperature (offset allowable temperature) was determined.

(Blocking resistance of toner) 2g of each toner was taken into a sample tube, and after tapping 500 times with a tap densityer, the temperature was 60°C, the relative humidity was 3.
496 for 2 hours, then 48
The toner was separated using a mesh sieve and the proportion of toner remaining on the sieve was measured. The results are shown in Table 1 below. In the table, "○" indicates that the proportion of residual toner is 10% or less, "△" indicates that the proportion of residual toner is more than 10% and less than 30%, and "x" indicates that it exceeds 30%.

(Actual photography test) An electrophotographic copying machine r U-Bix5000J (manufactured by Konica ■), which uses each of the above developers and has a latent image carrier made of a selenium photoreceptor and a toner recycling system.
A photocopy test was conducted using a modified machine in which a copy image was repeatedly formed 50,000 times, and the following items were evaluated.

In the live-action test, the temperature of the fixing heat roller was set at 160℃.
The environmental conditions were normal temperature and humidity of 20° C. and 60% relative humidity.

○Image Layer Degree Indicated by the relative density of the developed image when the image density of the original image is 1.3. The reflection density was measured using a "Sakura Densitometer" manufactured by Konica ■.

O Cleanability The surface of the photoreceptor was visually observed and evaluated.

○ Filming on photoconductor The surface of the photoreceptor was visually observed and evaluated.

○Durability Durability was evaluated based on the change in the amount of charge of the toner and the quality of the copied image by visual observation.

The charge amount of the toner was measured by blow-off method through a 350-mesh stainless steel screen. However, the blow pressure was 0.2 kg/crl and the professional time was 3 seconds.

The above results are shown in Table 1 below.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example of a toner recycling system, and FIG. 2 is an explanatory diagram showing another example of the toner recycling system. 20... Collection drum 21... Magnet 22...
・Transport belt 23...Cleaning mechanism 24
...Screw conveyor 25...Outlet 26...Developing mechanism 27
...Magnetic brush mechanism 28...Developer stirring mechanism 2
9... Toner receiving and distributing mechanism 30, 31... Roller 27a... Rotating sleeve 41... Developing mechanism 42
...Cleaning mechanism 43...Toner receiving and distributing mechanism 44...Magnetic brush mechanism 45...Latent image carrier 4
6...Screw conveyor

Claims (1)

[Claims] In an image forming method in which the toner used for developing an electrostatic image is recycled, base particles made of a copolymer obtained by block polymerization and/or graft polymerization of a crystalline polyester and an amorphous vinyl polymer are added to the base particles. An image forming method characterized by using a toner in which smaller resin particles are fixed by mechanical impact force.