JPS6031148A - Toner manufacturing method - Google Patents

Abstract

PURPOSE:To enhance durability and stability to environmental changes by subjecting polymerized particles contg. a colorant to cross-linking polymn. to grow them to prescribed times as large as the initial diameter of said particles. CONSTITUTION:A monomer is emulsion polymerized or fin polymerized particles contg. a colorant are produced to form particles having near 0.1mum size. Then, particles of about 1mum size are produced by the reprecipitation process. Further, these particles are grown to about 10mum diameter optimum for a toner and 3- 100 times the diameter just before by the cross-linking polymn. using a cross- linking agent. As the fine particle growth method, the seed polymn. method may be adopted or the particles may ge grown in diameter only by swelling them with another monomer and polymerizing them. The initial polymerized fine particles have an average particle diameter of 0.2-5mum, and a preferable final average particle diameter is 8-20mum. Superior durability and environmental stability can be obtained and the toner recovered from a cleaning step can be reused by thus coating the toner surface with the cross-linked polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing toner for use in electrostatography and other applications.

Toner for electrostatic photography can be developed using conventionally known developing methods, such as a two-component developing method such as a cascade development method in which the mixture is mixed with a carrier or a magnetic brush development method, or a toner containing a magnetic material or the like in the toner. It is used in one-component development methods that use magnetism to transport materials, as well as in pumping development methods.

Conventionally, various pulverization methods have been known for producing toner for electrostatic photography, in which thermoplastic resin is mixed with colorants, charge control agents, fluidity improvers, grinding aids, deafening agents, etc., and then pulverized and classified. ing. As other toner manufacturing methods, a suspension polymerization method is proposed in JP-A-53-17735, and an emulsion polymerization method is proposed in JP-A-52-108134. These toners are obtained directly by suspending or emulsifying polymerizable monomers, polymerization initiators, colorants, and other components in water.

However, in the former pulverization method, due to the natural law of ``pulverization'' itself, the particle size distribution is wide and the particles are irregularly shaped, and the classification yield becomes significantly poor in order to obtain a toner with a uniform particle size. In the latter case, even if a spherical product is obtained, suspension polymerization requires a large amount of dispersant such as a water-soluble polymer substance or a poorly soluble inorganic substance, and acid treatment or water washing is necessary to remove this. Even if this is done, a small amount remains on the surface of the toner, and moisture (humidity) in the air affects the electrical conductivity of the toner, making the triboelectric properties of the toner unstable.

In addition, in the suspension polymerization method and emulsion polymerization method, magnetic substances and colorants exist unevenly on the particle surface, and as a result, triboelectric charging characteristics become unstable, and clear copied images cannot be obtained. Although the present applicant has made proposals to solve various problems as described above, there still remain problems with the fluidity, environmental stability, and durability of Hutner. SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing an electrostatic photographic toner that overcomes the above-mentioned drawbacks.

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

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

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

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

Furthermore, the present invention is effective against changes in the copying environment (temperature, humidity changes, etc.).
This provides a stone toner with stable performance.

Further, the present invention provides a toner that does not have toner material adhering to the surface of a photoreceptor, toner holding member, or carrier surface.

Further, the present invention provides a toner that can be collected and reused after being cleaned after transfer.

The feature lies in the toner production method in which a crosslinking agent is used to carry out crosslinking polymerization when polymer particles containing a colorant are further grown to a diameter 3 to 100 times larger.

That is, conventional toners with a wide particle size distribution have non-uniform triboelectric charging performance. This is because triboelectric charging performance is related to the surface area of the toner and increases as the surface area increases. Therefore, the amount of triboelectric charge per unit weight of toner (Q/M-
The Q/M value (charge amount/toner weight) decreases as the surface area of the toner increases. Therefore, toner particles with a wide particle size are caused by non-uniform surface area. Therefore, it is a dream of those skilled in the art to obtain a toner having a uniform particle size, and extensive research has been carried out. Recently, various polymerization methods have been used to obtain toner particles of uniform particle size, but toner particles that are too fine or too coarse have been obtained. However, as a result of extensive research, the present inventors have found that uniform toner particles of around 10 μm can be obtained. On the other hand, it is known that when toner is made into a sphere, uniform triboelectric charging is achieved. Further, by making the toner particles spherical, the flow and mobility of the toner particles are improved, and the electrophotographic properties are improved. Furthermore, by coating the surface of the toner particles with a crosslinked polymer, the fluidity is further improved, making it possible to provide a toner that is particularly excellent in environmental stability, stability, and durability.

In the present invention, first, fine polymer particles containing a colorant are produced. It can be produced by emulsion polymerization of monomers or by the so-called reprecipitation method. Additives other than colorants may be added if necessary. As a result, in the case of the usual emulsion polymerization method, particles of around 0.1 μm are obtained. Further, in the reprecipitation method, particles with a size of about 1 μm can be obtained, although this varies depending on the resin concentration during reprecipitation, the stirring speed and method for precipitation, the type of poor solvent for precipitation, the amount added, etc.

Next, the particles obtained above are grown using a crosslinking agent to form a crosslinked polymer to a size of about 10 μm, which is the optimum particle size for a toner. As a method for growing particles, so-called seed polymerization, in which fine particles are grown as seed particles, may be used, or there is also a method in which the particle size is expanded by simply polymerizing the fine particles while swelling them with another monomer.

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

The specific group of surface materials used in the present invention is as follows.

Examples of the polymerizable hexamer used here include the following unsaturated compounds. Ethylene, propylene, 1-butene, 2-butene, 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-Hephtene, 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, acrylonide monolyl, acrylamide, methacryland, methyl acrylate, methyl methacrylate, ethyl acrylate, butyl methacrylate, N,N-dimethylacrylic acid, 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, cyamyl fuma rate,
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 free radical initiator or a redox catalyst is typically used as a 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, azobisisobutyronitrile, ammonium persulfate, sodium persulfate, potassium persulfate, perphosphoric acid There are potassium etc. Redox catalyst systems include sodium persulfate-nasylium formaldehyde sulfoxylate, cumene hydroperoxide-sodium metabisulfite, hydrogen peroxide-ascorubic acid, and the like. The concentration of polymerization initiator generally ranges from 0.3 to 0.8 wt %, based on monomer.

During polymerization, the following crosslinking agent is present.

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 dimethacrylate, dipropylene glycol dimethacrylate, polyethylene glycol dimethacrylate-methacryloxyjetoxyphenyl) propape 2,,
2T bis(4-acryloxyjethoxyphenyl)propane, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, tetramethylolmethanetetraacrylate, dibromneopentyl glycol dimethacrylate, allyl phthalate, 1,
Common crosslinking agents such as 2-propylene IJ col and 1,3-butanediol can be used as appropriate.

If these crosslinking agents are used in large amounts, they will not dissolve, resulting in poor fixing properties. Also, if the amount used is small, properties such as blocking resistance and durability required for toner will deteriorate, and during hot roll fixing, some of the toner will not completely adhere to the paper and will stick to the roller surface and be transferred to the next paper. It becomes difficult to prevent the offset phenomenon of metastasis. Therefore, the amount of these crosslinking agents used is o based on the total amount of monomers.
, ooi to 15% by weight (more preferably 0.1 to 10% by weight π).

Surfactants can be used to stabilize the polymerized particles. For example, anionic active agents include potassium palmitate, potassium stearate, potassium caprate, and potassium oleate.

Dodecyl sulfone [sodium salt, sodium laurate, sodium rosinate, 9 alkyl sodium sulfosuccinate, etc. Examples of cationic activators include long chain quaternary amine salts. Riluric acid and lauric acid are used as nonionic activators.

4h condensation of lysyllic acid, caproic acid (ethylene oxy), oleyl alcohol, cetyl alcohol,
There are ethylene oxide condensates such as lauric alcohol.

The above surfactants can be used alone or in combination. The surfactant concentration is generally determined by the critical micelle concentration (CMC).
) or less is preferable, but CMC or more may be added for the purpose of increasing the emulsion particle size or stabilizing the particles.

However, in this case, it is possible to use a polymerization inhibitor such as N2 (4SCN or copper salt) to prevent emulsion polymerization in the aqueous phase and suppress the generation of new particles.

Examples of water-bathable polymers in which the colorant is dispersed include cellulose ethers such as methylcellulose, ethylcellulose, benzylcellulose, carboxylmethylcellulose, carboxyethylcellulose, aminoethylcellulose, and oxyethylcellulose, natural polymers such as gelatin and starch, and polyvinyl alcohol. Generally, the above water-soluble polymers have a concentration of 1 to 10% by weight, preferably 3 to 7% by weight.
Used in weight%.

The coloring agent is selected from pigments and dyes that do not significantly inhibit polymerization. The amount added is preferably 5 to 50% by weight based on the total toner.

Furthermore, appropriate amounts of a charge control agent, a fluidity improver, and a mold release agent may be added.

The pH during polymerization is not particularly limited, but is usually in the range of 2 to 3. Further, the polymerization temperature is not particularly limited as long as it is within a range where normal emulsion polymerization can be carried out, but a range of 30 to 100°C is suitable.

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

[Example 1] Into a polymerization reactor equipped with a stirrer, a thermometer, a monomer dropping funnel, and a reflux condenser, 180 parts of ion-exchanged water, 1 part of Emulgen 920 (a nonionic surfactant manufactured by Kako Atlas Co., Ltd.), and 0 parts of benzoyl peroxide were added. Add 5 parts of magnetite to 20 parts of styrene monomer and 50 parts of a 5% aqueous solution of B-17 (polyvinyl alcohol manufactured by Denki Kagaku Co., Ltd.).
A seed latex was prepared by simultaneously dropping an aqueous solution in which 0 part was dispersed. The reaction was completed in 3 hours at a polymerization temperature of 70°C. The size of the particles was 0.2-0.3μ. Next, 50 parts of the above seed latex and 920 parts of Emulgen were added. 0.5
1 part to 160 parts of ion-exchanged water, and 20 parts of styrene monomer and 1 part of vinylbenzene were added dropwise over 3 hours to obtain a particle size in which magnetite was uniformly present in the center and covered with cross-linked styrene. is 8~12μ
A composite polymer lux was prepared. This latex was then spray-dried to obtain a toner.

[Comparative Example 1] A toner was obtained by performing the same operations as in Example 1 except that vinylbenzene was not used.

[Comparative Example 2] 100 parts of Stireme polymer (trade name I)-125, manufactured by Hercules Co., Ltd., 6 parts of magnetite (manufactured by Titan Kogyo Co., Ltd.)
After melt-kneading 0 parts and 2 parts of metal complex dye at 150°C,
After pulverization, particles of 5 to 20 μm were separated by classification, and then 0.5 μm of hydrophobic colloidal silica was externally added to obtain a toner. Next, the toner was transferred to an electronic copying machine (Canon group N
P400RE) and the results are shown in the table below, including Example 1 and Comparative Example 1.

After leaving the toner for one week (at 35 DEG C. and 90% RH), images were taken out and the density and image condition were compared.

As described above, the toner manufacturing method of the present invention provides extremely excellent durability and environmental stability by coating the toner surface with a crosslinked polymer, and furthermore, the toner recovered in the cleaning process can be reused. This makes it possible to obtain a very practical developer.

Claims (1)

[Claims] A method for producing a toner, in which crosslinking polymerization is performed using a crosslinking agent when polymer particles containing a colorant are further grown to a diameter 3 to 100 times larger.