JP2000112172A - Electrostatic charge image developing toner and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce an electrostatic charge image developing toner having good developing performance and transferability and containing a binder resin and a colorant. SOLUTION: A binder resin and a colorant are dissolved or dispersed in a solvent to prepare a mixed liquid. This mixed liquid is dispersed and suspended in an aqueous medium to prepare a suspension. The solvent is removed from the suspension. The resultant toner is dried by removing the water to <=3 wt.% in <10 min to produce the objective toner having 1-500 ppm concentration of the solvent and >=95% transfer efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner for developing an electrostatic image containing a binder resin and a colorant, which is used in an electrophotographic method or an electrostatic recording method, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, there have been known several methods for producing an electrostatic image developing toner used for developing an electrostatic latent image formed by electrophotography or electrostatic recording. As the most general method, there is a method of producing toner particles by making a polymer obtained by a polymerization reaction into fine particles in advance. Among them, the melt-kneading pulverization method is a method in which a coarsely pulverized polymer is pulverized using a fine pulverizer such as a mechanical rotary type or a jet type, and then classified to obtain toner particles. This is a method for producing a toner for developing an electrostatic charge image. However, the toner particles obtained by this method are not only irregular in shape and have a low transfer rate, but also have a high image quality because the particle size is not uniform and a small-diameter toner cannot be obtained. And the like.

[0003] Also, a method of forming particles by spraying a polymer solution previously dissolved in a solvent is known.
The toner particles produced by this method have disadvantages such as a non-uniform particle size and an increase in the size of an apparatus used for the production. Similarly, a method is known in which a poor solvent is added to a polymer solution previously dissolved in a solvent, or a polymer solution previously dissolved in a solvent is cooled to precipitate toner particles. Since the shape control of the obtained particles is difficult and the particle size is not uniform, there are the same drawbacks as in the kneading and pulverizing method.

[0004] In recent years, as a method for making the particle size uniform, toner particles are directly produced by a polymerization reaction such as a suspension polymerization method, an emulsion polymerization method, a seed polymerization method, or a dispersion polymerization method using a monomer as a starting material. There are known ways to do this. However, toner particles produced by these polymerization methods are difficult to remove residual monomers and surfactants,
It is difficult to internally add insoluble materials such as colorant, charge control agent and release agent, the type and particle size range of the obtained polymer are limited, and it is most suitable for particle formation every time the material composition is changed There are problems such as the necessity of examining various conditions. In particular, when a surfactant is mixed in the toner, there arises a problem that developability and transferability are deteriorated.

In recent years, polymer solutions previously dissolved in a solvent (
(A mixture of toner materials) in an aqueous medium.
A method of forming particles by removing the solvent by heating or reducing the pressure or the like (JP-B-61-28688, JP-A-63-25664, JP-A-7-152202, JP-A-9-92 No. -15902). (Hereinafter referred to as the dissolution suspension method)

[0006] The method of removing the solvent from the polymer solution suspension is that the toner has a uniform particle size, there is no residual monomer, and there is no need to remove the surfactant because no surfactant is used. Because there are many advantages such as easy addition of insoluble materials such as colorants, charge control agents and release agents, and easy cleaning of aqueous media.
It is considered to be a method suitable for improving the performance of the toner and industrialization.
On the other hand, copying machines, printers, and the like using electrophotography are moving toward waste-free in consideration of smaller size, lighter weight, higher speed, and environmental considerations. In order to apply to these systems, toners having higher developability and transferability are required. Dissolution suspension method toner has its shape controllability,
It shows excellent properties because it does not use a surfactant,
It is required to have higher characteristics.

Under such demands, Japanese Patent Application Laid-Open No. 7-325429 discloses a method of specifying the amount of residual solvent and the amount of water in a dried toner to obtain a toner having stable charging performance. No consideration is given to the time required for the drying step, and more than 10 minutes are spent for drying.By simply identifying the amount of residual solvent and water in the toner, the amount of the hydrophilic substance inside the toner can be reduced. Preventing precipitation and obtaining a toner having good characteristics is not sufficiently achieved. Further, JP-A-6-324517 discloses a toner obtained by suspension polymerization using a flash dryer,
There is known a method of instantaneously removing water, which aims at preventing aggregation of toner particles.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above situation in the prior art,
An object of the present invention is to provide a toner for developing an electrostatic image containing a binder resin and a colorant, which has good developability and transferability, and a method for producing the same.

[0009]

The above objects can be attained by providing the following toner for developing an electrostatic image and a method for producing the same. (1) An electrostatic image developing toner having a solvent concentration of 1 ppm or more and 500 ppm or less, wherein the transfer efficiency is 95% or more. (2) a step of preparing a mixture by dissolving or dispersing the binder resin and the colorant in a solvent; a step of preparing a suspension by dispersing and suspending the mixture in an aqueous medium; In the method for producing a toner for developing an electrostatic image, comprising a step of removing the solvent and a step of drying the obtained toner, the time for removing the water content of the toner to 3% by weight or less in the drying step is less than 10 minutes. The method for producing a toner for developing an electrostatic charge image according to the above (1), wherein in the production method, a flash dryer is preferably used in the drying step.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention and the like have made intensive studies in order to solve the above-mentioned problems, and as a result, have found that it is important to eliminate contamination on the toner surface. In other words, in the dissolution suspension method, since the toner is made in water, the ionic substance enters the toner by the water and the solvent slightly contained in the resin and is left behind when drying, but the surface contamination is removed by washing. Within the time until drying, the contamination remaining inside oozes out and the contaminants contaminate the surface.As a result, the toner for developing an electrostatic image formed by such a manufacturing method has high developability and transferability. It was discovered that there was no. In the dissolution suspension method as in the present invention, since a solvent is used, it is considered that the solvent slightly dissolved in water easily swells the toner resin and releases contaminants that have entered the inside of the toner together with the water onto the toner surface. .

In general, the toner for developing an electrostatic image has the following advantages if it prevents bleeding of contaminants from inside the toner to the surface. (1) Development efficiency and transfer efficiency are improved. This is considered to prevent the hydrophilic substance from precipitating from the inside of the toner and causing the attachment state of the external additive to be slightly different. (2) A toner with stable performance can be supplied. This is because the difference in toner characteristics due to the difference in the precipitation of the hydrophilic substance in each toner is eliminated by preventing the precipitation, and as a result, a stable toner is supplied. (3) A good copy image is stably obtained. This is because a hydrophilic substance on the toner surface adheres to the photoreceptor, and a paper chip or other foreign matter adheres thereon, thereby preventing the occurrence of a phenomenon such as white spots. (4) The developer life is extended. This is because paper chips and other foreign matter generated by the above mechanism are prevented from being taken into the developing machine, and as a result, a favorable environment is provided for the developer.

The toner of the present invention has a solvent concentration of 1 to 50.
It needs to be 0 ppm. Solvent concentration 500p
If it exceeds pm, aggregation tends to occur during storage of the toner, and contaminants easily migrate from the inside to the surface. Further, when the toner is used, a solvent odor is likely to occur. When the solvent concentration is less than 1 ppm, the productivity is reduced and the surface is liable to be deteriorated by long-term drying. The transfer efficiency of the toner of the present application is 9%.
It is necessary to be at least 5%. If the transfer efficiency is less than 95%, the color may be discolored when a full-color image is formed, and the image density may be reduced. In the present invention, as described above, drying is rapidly performed so that the time required for the water content in the toner to decrease to 3% by weight or less is less than 10 minutes.
By performing such drying, internal contamination is prevented from seeping out to the toner surface. As a result, the precipitation of the hydrophilic substance is prevented, and the above-mentioned advantages (1) to (4) are obtained. Also, according to the above manufacturing method,
The toner particles for developing an electrostatic charge image in which the structure of each toner is substantially uniform are produced.

Hereinafter, the toner for developing an electrostatic image of the present invention and the method for producing the same will be described in detail. The toner for developing an electrostatic image of the present invention has a solvent concentration of 1 ppm or more,
pm or less and the transfer efficiency is 95% or more. For example, it can be manufactured by the manufacturing method described below. In the method for producing a toner for developing an electrostatic image of the present invention, the above-described steps will be sequentially described. First, the first step in the present invention is a step of preparing a mixed solution by dissolving or dispersing a binder resin and a colorant in a solvent (hereinafter, this step is referred to as a “mixing step”). In this mixing step, a toner material containing at least a binder resin and a colorant is dissolved or dispersed in a solvent to obtain a mixed liquid of the toner materials.

In addition to a binder resin or a colorant, a release agent or a charge control agent usually added to toner particles may be appropriately added to the toner material, if necessary. The liquid mixture of the toner material may be obtained by previously kneading a binder resin with a colorant, a release agent or a charge control agent, or the like, or may be dissolved or dispersed in a solvent, or the binder resin may be dissolved in the solvent. After dissolution, the colorant, release agent, charge control agent, etc. may be dispersed using a media-containing disperser such as a ball mill or a sand mill or a high-pressure disperser, or the colorant, a mold release agent may be previously dispersed in a solvent. The binder resin may be dissolved after dispersing the agent or the charge control agent using a disperser containing a medium, a high-pressure disperser, an ultrasonic disperser, or the like. In this mixing step, any mixture may be used as long as the binder resin is dissolved in the solvent and the colorant is dispersed.

The binder resin used in the toner material of the present invention may be any of thermoplastic resins which can be dissolved in a solvent, such as a styrene-acrylic copolymer, a polyester resin, and a ketone. Resins, epoxy resins, polyolefin resins, and other thermoplastic resins used as binder resins for electrostatic image developing toners. As the colorant, carbon black, magnetic powder, cyan pigment, magenta pigment, yellow pigment, and other colorants for toner particles for electrostatic image development are used without any particular limitation. Examples of the release agent include petroleum wax, mineral wax, animal and vegetable wax, synthetic wax, and other release agents for toner particles for developing electrostatic images. Further, as the charge control agent, a quaternary ammonium salt compound and other charge control agents for toner particles for electrostatic image development are used without any particular limitation.

In the present invention, the solvent used for dissolving or dispersing the toner material includes ester solvents such as methyl acetate and ethyl acetate; ketone solvents such as methyl ethyl ketone and methyl isopropyl ketone; and aliphatic solvents such as hexane and cyclohexane. Examples thereof include hydrocarbon solvents, halogenated hydrocarbon solvents such as dichloromethane, chloroform, and trichloroethylene. These solvents are capable of dissolving the binder resin, have a water solubility of about 0 to 30% by weight, and preferably have a boiling point of 100 ° C. or lower. Note that it is preferable not to use a polymerizable monomer such as styrene or acrylic acid. In addition, when industrialization is performed, in consideration of work safety, cost, productivity, etc., cyclohexane is used when the binder resin is a polyolefin, and ethyl acetate is used when the other binder resin is used. It is particularly preferred to use These solvents have a viscosity of 1 at 20 ° C.
It is used so as to be in a range of 1 to 10,000 mPa · s, and preferably in a range of 1 to 2000 mPa · s. The above may be considered as the solvent slightly contained in the finally obtained toner.

Next, the second step in the present invention is the first step.
Is a step of preparing a suspension by dispersing and suspending the mixed liquid obtained in the mixing step in an aqueous medium (hereinafter, this step is referred to as a “dispersion suspension step”).

It is preferable to use an aqueous medium in which an inorganic dispersant is dispersed in water. In order to make the particle size distribution of the toner particles uniform, it is preferable to disperse the inorganic dispersant in water and to add a polymer dispersant soluble in water. This inorganic dispersant is dispersed in water using a disperser with media such as a ball mill, a high-pressure disperser or an ultrasonic disperser. The polymer dispersant may be added by any method as long as it is uniformly dissolved in water. The water used in the present invention is usually ion-exchanged water, distilled water or pure water.

As the inorganic dispersant, a hydrophilic dispersant is preferably used, and specific examples thereof include silica, alumina, titania, calcium carbonate, magnesium carbonate, tricalcium phosphate, clay, diatomaceous earth, bentonite and the like. Although mention may be made, calcium carbonate is particularly preferred.
Further, it is more preferable that these inorganic dispersants have their particle surfaces coated with a polymer having a carboxyl group. Since the particles coated with such a polymer can optimize the lipophilic-hydrophilic balance, the dispersed particles do not coalesce in the step of dispersing and suspending the mixture of the toner materials, and the toner particles having a sharp particle size distribution are obtained. Can be manufactured.
As the polymer having a carboxyl group, the carboxyl group of an α, β-monoethylenically unsaturated carboxylic acid or an α, β-monoethylenically unsaturated carboxylic acid is neutralized with an alkali metal, an alkaline earth metal, ammonium, an amine, or the like. Copolymer of at least one selected from alkali metal salts, alkaline earth metal salts, ammonium salts, amine salts and the like with α, β monoethylenically unsaturated carboxylic acid ester, or α, β mono The above-mentioned alkali metal salt, alkaline earth metal salt, ammonium salt or amine salt of a copolymer of an ethylenically unsaturated carboxylic acid and an α, β monoethylenically unsaturated carboxylic acid ester is included. These may be used alone or in combination of two or more.

Representative examples of the above α, β monoethylenically unsaturated carboxylic acids include α, β unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid and crotonic acid, maleic acid, fumaric acid, itaconic acid and the like. And at least one selected from α, β unsaturated dicarboxylic acids. Representative examples of the α, β monoethylenically unsaturated carboxylic acid esters include acrylic acid, methacrylic acid and other alkyl esters, acrylates and methacrylates having an alkoxy group, acrylates and methacrylates having a cyclohexyl group. Acrylates and methacrylates having a hydroxy group,
Examples thereof include polyalkylene glycol monoacrylates and polyalkylene glycol monomethacrylates. Those selected from α and β monoethylenically unsaturated carboxylic esters represented by these are preferred.

As these inorganic dispersants, those having an average particle diameter in the range of 1 to 1000 nm are used.
Those having a range of 5 to 500 nm are preferable, and those having a range of 10 to 300 nm are more preferable. When the average particle size is less than 1 nm, it is difficult to disperse the inorganic dispersant. When the average particle size is more than 1000 nm, the difference from the toner particle size becomes small, so that it is difficult to stably maintain the oil phase component. The amount of the inorganic dispersant used is preferably in the range of 1 to 300 parts by weight, more preferably 4 to 100 parts by weight, based on 100 parts by weight of the toner. If the amount is less than 1 part by weight, the dispersibility and stability tend to be unstable, and if it exceeds 300 parts by weight, the viscosity of the aqueous phase component increases, and the stability of the dispersed suspension tends to decrease.

As the above-mentioned polymer dispersant, a hydrophilic dispersant is preferably used, and among those having a carboxyl group, those not having a lipophilic group such as a hydroxypropoxyl group and a methoxyl group are preferable. Specifically, water-soluble cellulose ethers such as carboxymethyl cellulose and carboxyethyl cellulose are used, and carboxymethyl cellulose is particularly preferred. These celluloses have a degree of etherification of 0.6 to 1.5 and an average degree of polymerization of 50 to 3000. Further, the carboxyl group may be a metal salt such as sodium, potassium and magnesium. In the present invention, in order to sharpen the particle size distribution of the toner particles, it is desirable to change the amount of the polymer dispersant to be used depending on the viscosity of the mixed liquid of the toner materials (depending on the ratio of the toner material to the solvent, etc.). For example,
When the viscosity of the mixture of the toner materials is relatively low, it is not necessary to increase the viscosity of the aqueous medium, and the amount of the polymer dispersant added may be small. On the other hand, when the viscosity of the liquid mixture of the toner material is high, it is necessary to increase the amount of the polymer dispersant to increase the viscosity of the aqueous medium. The viscosity of the aqueous medium is adjusted so as to be approximately 1 to 3000 mPa · s at 20 ° C., preferably in the range of 1 to 1000 mPa · s.

The apparatus used in the dispersion suspension step includes:
Emulsifiers are not particularly limited as long as they are commercially available as dispersers, for example, Ultra Turrax (IKA), Polytron (Kinematica)
, TK Auto Homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.), batch-type emulsifier such as National Cooking Mixer (manufactured by Matsushita Electric Industrial Co., Ltd.), Ebara Milder (manufactured by Ebara Corporation),
TK pipeline homomixer, TK homomic line flow (manufactured by Tokushu Kika Kogyo), colloid mill (manufactured by Shinko Pantec), slasher, trigonal wet mill (manufactured by Mitsui Miike Kakoki), Cavitron (manufactured by Eurotech) )
, Fine flow mill (manufactured by Taiheiyo Kiko Co., Ltd.), batch or continuous dual-use emulsifier such as CLEARMIX (manufactured by M-Technic), FILMIX (manufactured by Tokushu Kika Kogyo), Microfluidizer (Mizuho Industrial)
Nano Maker, Nanomizer (Nanomizer), AP
V High-pressure emulsifier such as gourin (manufactured by Goulin), membrane emulsifier
Membrane emulsifier such as (Kyowa Kogyo Co., Ltd.), vibrating emulsifier such as vibro mixer (Kyoka Kogyo Co., Ltd.), ultrasonic homogenizer
(Made by Branson) and the like.

Next, the third step in the present invention is the second step.
Is a step of removing the solvent from the dispersion suspension obtained in the dispersion suspension step (hereinafter, this step is referred to as a “solvent removal step”). In this solvent removing step, the solvent in the dispersion suspension obtained in the above-mentioned dispersion suspension step is removed to obtain a toner dispersion. The toner dispersion obtained in this step needs to be a liquid in which the toner material and the inorganic dispersant are dispersed without drying.
The removal of the solvent from the suspension may be performed immediately after the dispersion suspension step. However, in order to make the particle size distribution of the obtained toner particles more uniform, the dispersion suspension step is terminated in order to stabilize the particle size distribution. Preferably, the solvent is removed after 1 minute or more. In this solvent removing step, it is preferable to remove or remove the solvent contained in the droplets of the suspension by cooling or heating the suspension obtained in the dispersion suspension step to a temperature in the range of 0 to 100 ° C. It is preferable to perform any of the following methods as a specific method of removing the solvent. (1) A gas stream is sprayed on the suspension to forcibly renew the gas phase on the suspension surface. In this case, a gas may be blown into the suspension. (2) Reduce the pressure to less than 10 to 760 mmHg. In this case, the gas phase on the suspension surface may be forcibly updated by purging the gas, or gas may be blown into the suspension.

If an inorganic dispersion stabilizer or the above-mentioned organic dispersion stabilizer (polymer dispersant) remains in the toner thus obtained while adhering to the surface of the toner, the residual adsorbed material has a hygroscopic property. For this reason, the humidity dependency of the charging property of the toner and the powder fluidity deteriorate. Therefore, it is preferable to remove such inorganic and organic dispersion stabilizers as much as possible in order to minimize the influence on the chargeability and powder fluidity of the toner. The obtained toner, after removing a small amount of residual solvent by drying, hydrochloric acid, nitric acid, formic acid, acetic acid and the like,
It is preferable to wash the inorganic dispersion stabilizer with an acid that makes the inorganic dispersion stabilizer water-soluble. As a result, the inorganic dispersion stabilizer remaining on the toner surface is removed. The polymer dispersant can be removed by washing with water. The acid-treated toner may be neutralized with an alkali such as sodium hydroxide if necessary. If necessary, it is collected by an appropriate method such as filtration, decantation, centrifugation, etc., and further washed with water or the like as necessary.

The fourth step in the present invention is a step of drying the toner produced in the above step (hereinafter, this step is referred to as "drying step"). In this drying step, the toner obtained in the above step is removed of water to obtain a toner for developing an electrostatic image. In the present invention,
In the drying step, the time for removing the water content of the toner to 3% by weight or less is less than 10 minutes. Such rapid drying makes it possible to prevent internal contamination from oozing on the toner surface. In the present invention, a flash dryer is used as a dryer,
It is even more preferred to dry within seconds.

The apparatus used in the drying step is not particularly limited as long as it satisfies the above-mentioned conditions and is generally a commercially available dryer or dryer.

When a flash dryer is used, the inlet temperature is 50 to 150 ° C., preferably 70 to 110, in consideration of drying efficiency and the like.
℃ is good.

The toner to be supplied to the flash dryer can be dried in any of mud, lump or powder form, and the water content of the supplied toner is desirably 20 to 95% by weight. The water content of the obtained toner is preferably 0.01 to 10% by weight. Note that the flash dryer is a device that disperses and dries a mud-like, lump-like, or granular material by an air stream, and transports the substance pneumatically with the air stream.

If necessary, a step of removing a very small amount of the residual organic solvent from the toner and a step of preparing a toner for developing an electrostatic image by sieving are added. In these steps, organic solvent removal and sieving may be performed by any method as long as the method does not cause aggregation or pulverization of the toner.

A known external additive may be added to the toner of the present invention in order to control fluidity and developability. As the external additive, various inorganic oxide fine particles such as silica, alumina, titania, and cerium oxide, and if necessary, hydrophobic fine particles, a vinyl polymer, and zinc stearate can be used. The external addition amount is from 0.05 parts by weight based on the toner before addition.
A range of 5 parts by weight is preferred.

The toner of the present invention is similar to a normal toner,
By combining with a carrier, an electrostatic image developing toner suitable as a two-component developer can be obtained.

When used as a two-component developer, the carrier may be iron powder, glass beads, ferrite powder, nickel powder, magnetite powder, or a resin coated on the surface thereof, or a resin and a charge controlling agent. And the like are kneaded with a magnetic material, pulverized and classified, and a resin dispersant carrier obtained can be used. Here, as the carrier used in combination with the toner,
It is preferable that the inorganic particles have a resin coating layer in which the surface of the inorganic particles is coated with a resin.

Next, an image forming apparatus used for forming an image using the electrostatic image developing toner of the present invention will be described. FIG. 1 is a schematic view showing an example of the image forming apparatus. In FIG. 1, reference numeral 1 denotes a photosensitive drum as an electrostatic latent image carrier, and the photosensitive drum 1 is a cylindrical member made of a conductive material. The photosensitive member layer 1b is formed as a thin layer on the surface of the member 1a. As the photoconductor layer 1b, for example, a negatively charged organic photoconductor (hereinafter, referred to as OPC) is used. Also,
For example, the outer diameter of the photosensitive drum 1 is 100 mm, and the surface moving linear velocity of the photosensitive drum 1, that is, the process speed is
Set to 160mm / s. The photoreceptor drum 1 is driven to rotate in the direction of the arrow by driving means (not shown). Around the photoreceptor drum 1, along a rotation direction thereof, a charger 2, an exposure unit 3, and a developer carrier including a cylindrical member
An electrophotographic recording means including a developing device 4 having a photoconductor 8 facing the photosensitive drum 1, a transfer corotron 5, a photo-static eliminator 6, and a fixing roll 9 is sequentially provided.

As the exposure means 3, any exposure means can be used as long as it can perform exposure according to image information. As the exposure means 3, any means such as a laser writing device, an LED array, a liquid crystal light valve comprising a uniform light source and a liquid crystal micro-shutter can be used according to the purpose. The exposure means 3 may be either one for performing image portion exposure or one for performing non-image portion (background portion) exposure, and is appropriately selected as necessary. In the present embodiment, a laser writing device was used to perform image portion exposure. Further, in the present embodiment, the development was reversal development. The toner is negatively charged and the carrier is positively charged.

FIG. 2 shows the transition of the surface potential of the photosensitive member in the charging, exposing, and developing steps when an image is formed using the developer of the present invention. For example, first, the charger
2, the surface of the photosensitive drum 1 is uniformly charged to -450 V [FIG. 2 (a)]. Subsequently, the image portion is exposed by a laser beam to form a negative latent image having an exposed portion potential of -200 V [FIG.
(b)]. Then, this negative latent image is developed with toner by the developing device 4 to be visualized [FIG. 2 (c)].

At this time, a developing bias is applied to the developer carrier 8 by a developing bias power source (not shown). For example, the developing bias is an AC voltage on which a DC voltage is superimposed. For example, the DC component of the developing bias voltage is
The voltage is set to -400 V in order to prevent the occurrence of background fog, and the AC component of the developing bias voltage is a rectangular wave having a frequency of 6 kHz and a peak-to-peak voltage of 1.5 kV in order to increase the developing efficiency.
The linear velocity of the surface movement of the cylindrical carrier 8 is, for example, 320 mm /
Set to s. Next, the recording paper 7 is fed onto the photosensitive drum 1 on which the toner image is formed, and the toner image on the recording paper 7 is transferred by the transfer corotron 5 and fixed by the heating roll 9. It should be noted that the surface of the photosensitive drum 1 after the transfer of the toner image and the step of peeling the recording paper 7 have been completed is subjected to exposure by the light neutralizer 6 to remove residual charges, and is ready for the next image recording step.

[0038]

EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. In the following description, “parts” and “%” mean “parts by weight” and “% by weight”, respectively. Example 1 [Mixing Step] Polyester resin composed of bisphenol A propylene oxide adduct / bisphenol A ethylene oxide adduct / terephthalic acid derivative (Tg 66 ° C., Tm 106 ° C.) 90 parts CI Pigment Blue 15: 3 5 parts Paraffin wax (melting point) (89 ° C.) 5 parts Ethyl acetate 100 parts The above components were dispersed in a ball mill for 24 hours to obtain 200 parts of a toner composition mixed solution in which a polyester resin was dissolved. The viscosity of the mixture was 500 cp.

[Dispersion and Suspension Step] Calcium carbonate (Luminous Maruo Calcium Co., Ltd., coated with an acrylic acid copolymer) 20 parts Carboxymethylcellulose (Selogen BS-H, Daiichi Kogyo Co., Ltd. 0.5 parts Ion-exchanged water 99) By dispersing the above components in a ball mill for 24 hours,
An aqueous medium (viscosity: 120 cp) in which carboxymethyl cellulose was dissolved was obtained. 15 kg of the obtained aqueous medium was transferred to TK.
Peripheral speed 20 by auto homomixer (made by Tokushu Kika Kogyo)
While stirring at a speed of m / s, 10 kg of the above-mentioned toner material mixture was charged, and the mixture was stirred for 1 minute and then stopped to obtain a dispersion suspension.
During the dispersion suspension, the container was cooled so that the dispersion suspension maintained 25 ° C. did.

[Solvent Removal Step] The suspension obtained in the dispersion suspension step was kept at 40 ° C. while stirring, and the gas phase on the suspension surface was forcibly renewed by a blower. A dispersion was obtained.

[Washing and Dehydration Steps] To 300 parts by weight of the dispersion obtained in the solvent removal step, 80 parts by weight of 10N hydrochloric acid was added, and the mixture was neutralized with a 0.1N aqueous sodium hydroxide solution. The replacement water washing was repeated four times to obtain a toner.

[Drying and Sieving Steps] The water content of the toner obtained in the dewatering step was removed using a spray dryer (Okawara Seisakusho), a type of flash dryer. The inlet temperature of the spray dryer was 120 ° C., and the toner was dried within 5 seconds. The water content of the obtained toner was measured by a Karl Fischer method automatic water content analyzer (manufactured by Mitsubishi Chemical Corporation), and a value of 3% was obtained. Subsequently, the solvent was removed with a drier and sieved with a 45 μm mesh.

<Measurement of Solvent Concentration> To 1 part by weight of the prepared toner, 2 parts by weight of 2-propanol was added, dispersed by ultrasonic waves for 30 minutes, stored in a refrigerator for at least one day, and the solvent in the toner was extracted. . The supernatant is subjected to gas chromatography (GC14A, SHI
MADZU), and the solvent concentration in the toner was determined by quantifying the solvent in the toner. The measurement conditions are as follows. The solvent concentration of this toner was 50 ppm. . Device; Shimadzu GC-14A Column; CBP20-M50-0.25 detector; FID Injection amount; 1～5Myueru carrier gas; He2.5kg / cm ² hydrogen flow rate; 0.6 kg / cm ² air flow rate; 0.5 kg / cm ² chart speed; 5 mm / min speed; Range 10 ¹ × Atten 2 ⁰ column temperature; 40 ℃ Injection Temp; 150 ℃

[Addition of External Additive, Mixing of Carrier] To the prepared toner, 0.5 parts by weight of silica (R972, Nippon Aerosil) was added using a Henschel mixer. Ferrite powder as carrier core for this toner (F300: Powder Tech)
A carrier coated with 0.5 parts by weight of polymethyl methacrylate resin and kneader was prepared, and the toner concentration by weight was 8%.
And a developer was prepared.

<Evaluation of transferability>
An apparatus modified from Color 635 (manufactured by Fuji Xerox) was used. The transfer rate was calculated from the following equation and evaluated. Table 1 shows the results. Transfer efficiency (%) = weight of toner transferred to paper / (weight of toner transferred to paper + weight of untransferred toner on photosensitive drum) × 100 A clear image was obtained without any fog.

<Evaluation of Image Density> The image density was measured for a solid image with a reflection densitometer (X-RITE130, manufactured by X-rite). (○ ・ ・ 1.3 or more, × ・ ・
(Less than 1.3)

Example 2 A polyester resin as a binder resin used in the method of Example 1 was converted to a styrene acrylic resin (Tg; 65 ° C., weight average molecular weight: 200
000) in place of the spray dryer of the drying and sieving process, except that drying was performed using a flash jet dryer (manufactured by Seishin Enterprise) which is a type of flash dryer. An electrostatic image developing toner was manufactured. Flash jet dryer inlet temperature is 80
C. and the toner was dried for 0.5 to 30 seconds to obtain a toner having a water content of 3%. The solvent concentration of this toner was 150 ppm. Evaluation was performed in the same manner as in Example 1. As a result, a clear image was obtained without any fog. Table 1 shows the results.

Example 3 The procedure of Example 1 was repeated, except that drying was performed using a vibrating fluidized drier (manufactured by Chuo Kakoki Co., Ltd.) instead of the spray dryer in the drying and sieving process. A toner for developing a charge image was obtained. The processing volume of the vibrating fluidized drier was 100 g, the hot air temperature was 80 ° C., and drying was performed for 5 minutes to obtain a toner having a water content of 3%. The solvent concentration of this toner was 350 ppm.
When evaluation was performed in the same manner as in Example 1, there was no fog,
A clear image was obtained. Table 1 shows the results.

Example 4 The procedure of Example 1 was repeated, except that drying was performed using a vibrating fluidized drier (manufactured by Chuo Kakoki) instead of the spray drier in the drying and sieving steps. A toner for developing a charge image was obtained. Vibration fluidized dryer throughput is 10
0 g, hot air temperature of 75 ° C., and drying for 8 minutes to obtain a toner having a water content of 3%. The solvent concentration of this toner was 100 ppm. Evaluation was performed in the same manner as in Example 1. As a result, a clear image was obtained without fogging. Table 1 shows the results.

Example 5 The toner obtained by the method of Example 1 was evaluated under the following conditions. [Addition of external additives and mixing of carriers] The average particle diameter of the particles treated hydrophobically with hexamethylene disilazane is 30 to 40 nm.
Silicon oxide particles in the range of 20 nm to 80 nm (Trefil F-1
00: Toray) with a Henschel mixer-type mixer at a peripheral speed of the blade of 30 m / sec.
t% adhered. As a carrier core, a carrier was prepared by coating 3.5 parts by weight of polymethyl methacrylate on Cu-Zn ferrite (F35: Powder Tech) with a heating kneader and sieving to collect 35 μm particles. The specific resistance of this carrier was 3.2 × 10 ¹⁵ Ωcm, and the saturation magnetization was 55 emu / g. 20 parts by weight of the toner and 100 parts by weight of the carrier are V
The mixture was mixed with a mold blender to obtain a developer.

<Evaluation of Transferability> To evaluate the developer of this example, an image forming apparatus as shown in FIG. 1 was used. The image forming conditions and the like are as follows. (Image formation conditions) Photoreceptor OPC (φ84) ROS LED (400dpi) Process speed 100mm / s Latent image potential Background part = -600V, Image part = -100V Developer support Non-magnetic endless film (100 μm thick. Dispersion of carbon black in polycarbonate resin.Electric resistance = 108Ω ・ cm) Magnet roll Magnetic flux density = 22mT (on developer conveying member) Roll diameter = φ20 Roll rotation speed = 300mm / s Developer carrier and magnet Maximum gap with roll = 2mm Distance between photoconductor and developer carrier = 0.5mm Thickness of developer layer 0.5mm Development bias DC component = -550V AC component = 1.5kVP-P (1.5kHz) Transfer corotron 40 μm Tungsten wire 6.0Kv Fixing machine 160 ° C heating / Teflon coated heat roll Print test environment 22 ° C, 55% RH No fog at all, and clear images were obtained.

Example 6 100 parts of the toner obtained by the method of Example 2 was used.
1.3 parts of hydrophobic silica (R972: manufactured by Aerosil) and 1.0 part of titania particles were externally added and mixed with a Henschel mixer, and evaluated by the following method. <Evaluation of Transferability> The image forming apparatus used for evaluating the image quality of the non-magnetic one-component developer will be described below. After the latent image holding member was charged with a roller charger, the latent image was exposed to laser light to form an electrostatic latent image, and a thin layer was formed on an aluminum developer carrier using a urethane rubber layer forming blade. Develop with the agent. Here, in order to stabilize the conveyance of the toner, a developer supply roller rotating in the opposite direction to the developer carrying member was arranged in contact with the developer carrying member. The toner developed on the latent image holding member is transferred to transfer paper by a contact-type transfer roller and thermally fixed. The cleaning of the residual toner on the latent image holding member was performed using a blade type cleaner. Here, the peripheral speed of the photoconductor is 100 mm / s, the peripheral speed of the developer carrier is 170 mm / s, and an AC voltage and a DC voltage are applied to the developer carrier and the developer supply roller to apply an electrostatic latent image. Was developed. There was no fog and a clear image was shown.

Comparative Example 1 In the method of Example 3, the throughput of the vibrating fluidized drier was set to 100
g, the hot air temperature was set to 70 ° C., and dried for 12 minutes to obtain a toner having a water content of 3%. The solvent concentration of this toner was 450 ppm. The evaluation was performed in the same manner as in Example 1. Some fog was observed. Table 1 shows the results.

Comparative Example 2 In the method of Example 3, the throughput of the vibration fluidized drier was set to 500
g, hot air temperature 45 ℃, dried for 60 minutes, moisture content 3%
Was obtained. The solvent concentration of this toner was 600 ppm. The evaluation was performed in the same manner as in Example 1. Fog was observed. Table 1 shows the results.

Comparative Example 3 In the drying and sieving step of the method of Example 1, the electrostatic charge was the same as in Example 1 except that drying was performed using a thermostat (manufactured by Tabai Espec) instead of a spray dryer. An image developing toner was obtained. The processing amount of the incubator was 1.5 kg, the drying temperature was 45 ° C., and drying was performed for 3 hours to obtain a toner having a water content of 3%. The solvent concentration of this toner was 300 ppm.
The evaluation was performed in the same manner as in Example 1. Fog was observed. Table 1 shows the results.

Comparative Example 4 The toner obtained by the method of Comparative Example 1 was evaluated in the same manner as in Example 5. Fog was observed. Table 1 shows the results.

[0057]

[Table 1]

[0058]

According to the method of the present invention, a conventional toner for developing an electrostatic image using an arbitrary polymer as a binder resin, including a polymer which has not been able to be ground by a simple operation, is used. Method compared to toner particles
It is possible to easily form a toner for developing an electrostatic charge image having good developability and transferability and without fogging.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of an image forming apparatus for forming an image using the electrostatic image developing toner of the present invention.

FIG. 2 shows a photoconductor surface potential in each step when an image is formed using the toner for developing an electrostatic image of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor drum 2 Charger 3 Exposure means 4 Developing device 5 Transfer corotron 6 Light eliminator 8 Developer carrier 9 Heating roll

Continued on the front page (72) Inventor Takashi Hara 1600 Takematsu, Minamiashigara-shi, Kanagawa Prefecture F-Xerox Co., Ltd. F-term (reference) 2H005 AB03 AB09 EA10

Claims (3)

[Claims] Claims 1. A solvent concentration of 500 ppm when the concentration is 1 ppm or more.
The toner for developing an electrostatic image described below, wherein the transfer efficiency is 95% or more. 2. A step of preparing a mixture by dissolving or dispersing a binder resin and a colorant in a solvent; a step of preparing a suspension by dispersing and suspending the mixture in an aqueous medium; A step of removing the solvent from the suspension, a method of producing a toner for developing an electrostatic image, comprising a step of drying the obtained toner;
2. The method according to claim 1, wherein the time for removing the water content of the toner to 3% by weight or less in the drying step is less than 10 minutes. 3. The method according to claim 2, wherein a flash dryer is used in the drying step.