JPH0713751B2 - Toner manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a toner used for electrostatic photography and the like.

The toner for electrostatic photography contains a conventionally known developing method, for example, a two-component developing method such as a cascade developing method which is used by mixing with a carrier, or a magnetic brush developing method, and a toner containing a magnetic substance. One-component developing method for transporting by utilizing the method, or, as previously proposed by the applicant, used for a jumping developing method in which triboelectric charging with a sleeve is applied to fly to a latent image. Is.

Conventionally, a so-called pulverization method in which a toner for electrostatic photography is kneaded by adding a colorant, a charge control agent, a fluidity improving agent, a pulverization aid, a release agent, etc. to a thermoplastic resin and then pulverizing and classifying is known. There is. As other toner production methods, the turbidity polymerization method is disclosed in JP-A-53-17735, and the emulsion polymerization method is disclosed in JP-A-52-10813.
Proposed in No. 4 etc. These are those in which a polymerizable monomer, a polymerization initiator, a colorant and other compositions are turbid or emulsified in water to directly obtain a toner.

However, in the former pulverization method, due to the natural law of "pulverization" itself, the particles have a wide particle size distribution and become irregularly shaped particles, and the classification yield remarkably deteriorates in order to obtain a toner having a uniform particle diameter. In the case of the latter, even if spherical ones are obtained, suspension polymerization requires a large amount of a dispersant such as a water-soluble polymer substance or a hardly soluble inorganic substance, and acid treatment or washing with water is necessary to remove this. Even if it is carried out, a small amount remains on the toner surface, and the moisture (humidity) in the air affects the electric conductivity of the toner and the like, and the triboelectric charging property of the toner becomes unstable.

Further, in this suspension polymerization method or emulsion polymerization, the magnetic substance and the colorant are nonuniformly present on the surface of the particles, and as a result, the triboelectrification characteristic becomes unstable, and a clear copy image is not obtained. The applicant of the present invention is proposing to solve various problems as described above, but the toner fluidity and environmental stability,
There was a problem with durability. An object of the present invention is to provide a method of manufacturing an electrophotographic toner that solves the above-mentioned drawbacks.

An object of the present invention is to provide a toner in which a coloring agent such as a magnetic material is uniformly present inside toner particles.

Another object of the present invention is to provide a toner having a spherical particle diameter of 10 μm or less and a narrow particle diameter distribution.

A further object of the present invention is to provide an electrophotographic toner having excellent environmental stability and durability.

Further, the present invention provides a toner that does not change its characteristics when left in a developing device or a storage container for a long period of time or stored.

Furthermore, the present invention is applicable to changes in the copying environment (temperature, humidity changes, etc.).
To provide a toner having stable performance.

Further, the present invention provides a toner having no toner agent attached to the surface of the photoreceptor, the surface of the toner holding member or the surface of the carrier.

Further, the present invention provides a toner capable of collecting and reusing the toner cleaned after the transfer.

Specifically, the present invention produces polymer particles containing a colorant in an aqueous phase, and then conducts a cross-linking polymerization reaction using a polymerizable monomer and a cross-linking agent to reduce the diameter of the polymer particles to 3 ~
The present invention relates to a method for producing a toner, wherein the toner particles are grown 100 times to produce toner particles.

That is, the conventional toner having a wide particle size distribution has non-uniform triboelectrification performance. The triboelectric charging performance is related to the surface area of the toner and increases as the surface area increases. Therefore, the triboelectric charge amount per unit weight of toner (Q / M = charge amount / toner weight) becomes Q / M as the surface area of the toner increases.
The value increases. Therefore, a toner having a wide particle size distribution contains coarse toner particles and fine toner particles,
Due to the large surface area difference between each toner particle,
The difference in the triboelectric charge amount between the toner particles becomes large. Therefore, it is a dream of those skilled in the art to obtain a toner having a uniform particle size, and earnest research has been conducted. Recently, it has become possible to obtain a uniform particle size by using various polymerization methods.
Or, only the ones that are too rough are obtained. But,
As a result of earnest research, the present inventor has found that uniform toner particles with a size of 10 μm or less can be obtained. On the other hand, it is known that triboelectrification becomes uniform when the toner has a spherical shape. Further, by making the toner particles spherical, the fluidity of the toner particles can be improved and the electrophotographic characteristics can be improved. Further, by coating the surface of the toner particles with the cross-linked polymer, it is possible to provide a toner having further improved fluidity and particularly excellent environmental stability and durability.

The present invention first produces fine polymerized particles containing a colorant. As a method for producing, a monomer is emulsion polymerized, or a so-called reprecipitation method is used. If necessary, additives other than the colorant are added. As a result, in the case of the usual emulsion polymerization method, particles within 0.1 μm are obtained. In the reprecipitation method, particles having a particle size of 1 μ or less can be obtained, although it varies depending on the resin concentration at the time of reprecipitation, the stirring speed for precipitation, the method, the type of poor solvent for precipitation, the addition amount, and the like.

Next, the above-obtained particles are grown while forming a cross-linked polymer using a cross-linking agent up to a size of 10 μm which is the optimum particle size as a toner. As a method for growing particles, so-called seed polymerization in which fine particles are grown as seed particles may be used, and there is also a method in which the fine particles are simply polymerized while swelling the fine particles to enlarge the particle size.

It is preferable that the first fine polymer particles have an average particle size of 0.2 to 5 μm, and the finally obtained toner has an average particle size of 8 to 20 μm.

Specific material groups used in the present invention are as follows.

The polymerizable monomer used here includes the following unsaturated compounds. Ethylene, propylene, 1-butene, 2-butein, isobutylene, 1-pentene, 2-
Methyl-2 butene, 1-hexene, 4-methyl-1-pentene, 3,3-dimethyl-1-butene, 2,4,4-trimethyl-1-pentene, 6-ethyl-1-hexene, 1-heptene , 1-octene, styrene, α-chlorostyrene, α-methylstyrene, allylbenzene, phenylacetylene, vinylnaphthalene, 4-methylstyrene, 2,
4-dimethylstyrene, 3-ethylstyrene, 2,4-diethylstyrene, 2-methoxystyrene, 4-chlorostyrene, 4-fluorostyrene, 3-iodostyrene, 4
-Cyanostyrene, 3-nitrostyrene, 2-aminostyrene, acrylic acid, methacrylic acid, acrolein, methacrolein, acrylonitrile, acrylamide,
Methacrylamide, methyl acrylate, methyl methacrylate, ethyl acrylate, butyl methacrylate, N, N-dimethylacrylamide, vinyl chloride, vinylidene chloride, vinylidene fluoride, trichloroethylene,
Vinyl acetate, vinyl propionate, vinyl butyrate, vinyl benzoate, vinyl formate, vinyl oleate, vinyl adipate, maleic anhydride, dimethyl fumarate, dipropyl fumarate, diamyl fumarate, etc.

As the catalyst, crosslinking agent surfactant, buffer and other components used in the present invention, those used in well-known emulsion polymerization can be used.

A typical free radical initiator or a redox catalyst is used as the polymerization initiator. For example, free radical initiators include hydrogen peroxide, peracetic acid, t-butyl hydroperoxide, di-t-butyl peroxide, dibenzoyl peroxide, perbenzoic acid, t-butyl peracetate, azobisisobutyrate. Examples include ronitrile, ammonium persulfate, sodium persulfate, potassium persulfate, and potassium perphosphate. As the redox catalyst system, sodium peroxide-formaldehyde sulfoxylate sodium,
Cumene hydroperoxide-sodium metabisulfite, hydrogen peroxide-ascorbic acid and the like. The concentration of the polymerization initiator is generally in the range of 0.3 to 0.8 wt% with respect to the monomer.

At the time of polymerization, the following cross-linking agent is present for polymerization.

Divinylbenzene, divinylnaphthalene, divinyl ether, divinyl sulfone, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, 1,3-butylene glycol dimethacrylate , 1,6-hexane glycol dimethacrylate, neopentyl glycol dimethacrylylate, dipropylene glycol dimethacrylate, polypropylene glycol dimethacrylate, 2,2'bis (4-methacryloxydiethoxyphenyl) propane, 2,2'bis ( 4-acryloxydiethoxyphenyl) propane, trimethylolpropane trimethacrylate, trime Triacrylate, tetra methylol methane tetraacrylate,
A general crosslinking agent such as dibromneopentyl glycol dimethacrylate, allyl phthalate, 1,2-propylene glycol, and 1,3-butanediol can be appropriately used.

If these crosslinking agents are used in a large amount, they will not dissolve and the fixability will be poor. If the amount used is small, properties such as blocking resistance and durability required as a toner deteriorate, and during heat roll fixing, part of the toner adheres to the roller surface without completely sticking to the paper, It becomes difficult to prevent the offset phenomenon of transfer. Therefore, the amount of these cross-linking agents used is 0.
It is preferable to use 001 to 15% by weight (more preferably 0.1 to 10% by weight).

Surfactants can be used to stabilize the polymerized particles. Examples of the anionic activator include potassium palmitate, potassium stearate, potassium caprate, potassium oleate, sodium dodecylsulfonate, sodium laurate, sodium rosinate, alkyl sodium sulfosuccinate and the like. Examples of cationic activators include long-chain quaternary amine salts. Examples of the nonionic activator include ethylene oxide condensates of linoleic acid, lauric acid, ricinoleic acid and caproic acid, and ethylene oxide condensates of oleyl alcohol, cetyl alcohol and lauric alcohol.

The above surfactants can be used alone or in combination. Surfactant concentration is generally the critical micelle concentration (CMC)
The following are good, but CMC or more may be added for the purpose of increasing the emulsion particle size and stabilizing the particles. However, at this time, use a polymerization inhibitor such as NH ₄ SCN or copper salt,
It is possible to employ a method of preventing emulsion polymerization in the aqueous phase and suppressing the generation of new particles.

The water-soluble polymer in which the colorant is dispersed is, for example, cellulose ether such as methyl cellulose, ethyl cellulose, benzyl cellulose, carboxymethyl cellulose, carboxyethyl cellulose, aminoethyl cellulose, oxyethyl cellulose, natural polymer such as gelatin and starch, polyvinyl alcohol and the like. Generally, the above water-soluble polymers are contained in a concentration of 1 to 10% by weight, preferably 3 to 7
Used in weight percent.

The colorant is selected from pigments and dyes that do not significantly inhibit polymerization. 5 to 50% by weight of the total toner
Is good.

Further, a charge control agent, a fluidity improver, and a release agent may be added in appropriate amounts.

The pH during the polymerization is not particularly limited, but it is usually in the range of PH2 to 3. Further, the polymerization temperature is not particularly limited as long as it is a range in which ordinary emulsion polymerization is carried out, but a range of 30 to 100 ° C is suitable.

Next, examples will be shown. All parts are parts by weight.

[Example 1] 180 parts of ion-exchanged water and Amalgen 9 were put into a polymerization reactor equipped with a stirrer, a thermometer, a dropping funnel for monomer and a reflux condenser.
20 (Kao Atlas nonionic surfactant) 1 part, benzoyl peroxide 0.4 parts were charged, and styrene monomer 2 was added thereto.
0 parts and B-17 (polyvinyl alcohol manufactured by Denki Kagaku)
An aqueous solution in which 50 parts of magnetite was dispersed in 50 parts of 5% aqueous solution was simultaneously dropped to prepare a seed latex. The reaction was completed in 3 hours at a polymerization temperature of 70 ° C. The size of this particle is
It was 0.2 to 0.3μ. Next, 50 parts of the above-mentioned seed latex and 0.5 part of Emulgen 920 were added to 160 parts of ion-exchanged water, and a polymerizable monomer composition containing 20 parts of styrene monomer, 1 part of divinylbenzene and 0.4 part of benzoyl peroxide was added thereto. Was dropped over 3 hours to prepare a composite polymer lax in which magnetite was uniformly present in the central portion and which was covered with crosslinked styrene and had a particle diameter of 8 to 12 μm. Then, this latex was spray-dried to obtain a toner.

[Comparative Example 1] A toner was obtained in the same manner as in Example 1, except that divinylbenzene was not used.

[Comparative Example 2] 100 parts of styrene polymer (trade name D-125, manufactured by Hercules Co., Ltd.), 60 parts of magnetite (manufactured by Titanium Industry Co., Ltd.), and 2 parts of metal complex salt dye were melt-kneaded at 150 ° C, and then finely pulverized,
Toner particles of 5 to 20 μm were selected by classification to prepare a toner.

Experimental Example To each of the magnetic toners of Example 1 and Comparative Examples 1 and 2, 0.5% of hydrophobic colloidal silica was externally added to prepare a one-component magnetic developer, and the one-component magnetic developer was applied to an electronic copying machine. (Canon NP400RE) was introduced and a copy test was conducted.
The results are shown in the table below. The one-component magnetic developer containing the magnetic toner prepared in Example 1 was more resolvable than that of the magnetic toners of Comparative Examples 1 and 2 and was durable for a large number of sheets, stable in triboelectrification, and recovered by cleaning. The toner development characteristics and environmental stability were excellent.

Comparative Example 3 Toner particles were produced in one step by a suspension polymerization method using a polymerizable monomer consisting of styrene monomer-40 parts, divinylbenzene 1 part, magnetite 36 parts and benzoyl peroxide. A magnetic toner having a wide particle size distribution consisting of toner particles having a diameter of 5 to 30 μm was obtained.

As described above, according to the toner manufacturing method of the present invention, by coating the surface of the toner with the cross-linked polymer, excellent durability and environmental stability are obtained, and the toner collected in the cleaning step can be reused. It is possible and a very practical developer can be obtained.

Claims (2)

[Claims] 1. A polymer particle containing a colorant is produced in an aqueous phase, and then a cross-linking polymerization reaction is carried out using a polymerizable monomer and a cross-linking agent to increase the diameter of the polymer particle to 3 to 100 times. A method for producing a toner, which comprises growing the toner particles to produce toner particles. 2. The method for producing a toner according to claim 1, wherein the average particle diameter of the polymer particles is 0.2 to 5 μm.