JPS60151648A - Electrostatic charge image developing toner and its manufacture - Google Patents

Abstract

PURPOSE:To enhance fluidity and stability of triboelectric characteristics by forming one or more coat layers made of polymer particles alone or contg. a colorant on a coat layer made of a mixture of the colorant and fine polymer particles. CONSTITUTION:Core particles made substantially of spherical polymer particles and a colorant are added to a disperse system of fine polymer particles under conditions not causing agglomeration and coalescence of these fine polymer particles, and after uniformly dispersing them, they are spray dried at the glass transition point of the polymer or higher to form the first coat layer 2 composed of the polymer and the colorant on the surface of each core particle 1. Further, the second coat layer 3 and the third coat layer 4 both made of the polymer alone or contg. the colorant are formed likewise on the first layer to obtain a toner. The toner thus obtained is superior in fluidity and stabilized in triboelectric characteristics and enhanced in functional performance.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a toner for developing electrostatic images in electrophotography, electrostatic recording, electrostatic printing, etc., and a method for producing the toner.

Conventionally, electrostatic charge developing agents 1 to 1 are produced by melt-kneading a soft polymer and a colorant, dispersing the colorant in the polymer, and finely pulverizing the colorant-dispersed polymer. However, the fine powder obtained by this manufacturing method has a very wide particle size distribution, and in order to obtain a toner that can be put to practical use, it must be further classified, which ultimately complicates the manufacturing process and increases costs. That's the drawback. Another disadvantage was that the product particles had an amorphous shape, resulting in poor fluidity.

On the other hand, a production method using a polymerization method has been proposed as a method for directly producing colored polymer fine particles without a pulverization process (
For example, Special Publication No. 36-10231, No. 47-5183
No. 0, 51-14895@, JP-A-53-17735
No. 53-17736, Oni and No. 53-17737).

These are based on the so-called suspension polymerization method, in which a polymerizable composition containing a polymerizable monomer, a polymerization initiator, and a colorant is suspended in an aqueous dispersion medium and polymerized to directly produce toner. It is something to do.

In this method, the toner particles produced are spherical,
It has the advantages of excellent fluidity, simple manufacturing process, and low cost, but it is difficult to make the particle size distribution uniform, and it is impossible to create a functional toner with a coating layer. It is.

This invention has the characteristics of a conventional l-ner for electrostatic images, but also has excellent fluidity (spherical shape), stable charge characteristics (narrow particle size distribution), and,
The purpose of this invention is to obtain a toner with improved functionality (multilayer structure), especially a charge-dependent toner.

Structure The structure of the present invention includes: (1) a core particle made of a substantially spherical polymer; a first coating layer provided on the surface of the core particle and made of a mixture of at least a colorant and fine polymer particles; , an electrostatic charge developing toner having a multilayer structure comprising at least one coating layer formed of at least polymer particles or a mixture of polymer particles and a colorant, provided on the first coating layer; and (2) Core particles consisting of a substantially spherical polymer and a coloring agent are added to a dispersion system of micro polymer particles under conditions that do not cause aggregation or coalescence of the micro polymer particles, and after uniformly dispersing the micro polymer particles. Glass transition temperature of particles (T(+
>By spray drying at a temperature above, a first coating layer consisting of a mixture of a polymer and a colorant is formed on the surface of the spherical core particles. Production of an electrostatic charge developing toner in which a multilayer structure is formed by forming a new coating layer made of a polymer or a mixture of a polymer and a colorant at least once in the same manner as in the formation of the first coating layer. It's a method.

The structure of the above-mentioned toner will be explained in detail with reference to FIG. 1. First, on the 7 surfaces of the spherical core particles 1, there is a first coating layer 2 made of a mixture of at least a colorant and fine polymer particles. It is a toner having thereon a second coating layer 3 consisting of polymer particles or a mixture of polymer particles and a colorant, or also a third coating layer 4 of the same type.

These core particles or coating layers are explained as follows: A) The spherical polymer core particle material is transparent particles of thermoplastic plastic such as acrylic acid ester resin or styrene resin. These core particles can be purchased commercially, but they can be produced by conventional granulation methods such as spray drying, suspension polymerization, organic solvent dispersion polymerization, and seed emulsion polymerization.

There is a permissible particle size range of about 1 to 20 microns for toner cores, but uniform particle size distribution (having a variation within ±25% with respect to the average particle size value) in this invention is 1. −
In order to make a nuclear material, it is necessary to make the particle size distribution of the core particles uniform. Therefore, when considering the above manufacturing methods for this purpose, the spray drying method and the suspension polymerization method require classification after granulation, but the organic solvent dispersion polymerization method and the seed emulsion polymerization method do not require classification. .

B) Coating layer consisting of a mixture of colorant and polymer The spherical core particles and colorant are added to the fine polymer particle dispersion system under conditions that do not cause aggregation or coalescence of the fine polymer particles, and the colorant is uniformly dispersed. After being dispersed, a first coating layer 2 made of a mixture of polymer and colorant is formed on the surface of the spherical core particles by spray drying at a temperature higher than the glass transition temperature (Tg) of the fine polymer particles. do.

The important point in forming the WI layer is to maintain the stability of the fine polymer particles (latex particles) against pl-1 change and mechanical shearing action. To explain these specifically, 1. The emulsifier is a condensate of an alkyl (benzene) sulfate, an alkyl sulfate ester salt, a sodium sulfate, etc., and the amount thereof is 0.00 parts per 100 parts of the resin.
It is 5 to 10 parts by weight, preferably 1 to 5 parts by weight.

2. pH control: l) H8 or higher is appropriate, preferably pH9 or higher.

3. In order to suppress the increase in viscosity, it is necessary to adjust the stirring power from time to time.

As the polymerizable monomer for producing the latex particles of this invention, any polymerizable monomer can be used, and it may be a self-polymerizable vinyl monomer, or, for example, Although monomers such as dibasic acids and glycols can be used to produce polyester resins,
Vinyl monomers are preferred.

Specific examples of the polymerizable monomers used in this invention are listed below.

For example, ', styrene, 0-methylstyrene, m-methylstyrene, p-methylstyrene, p-ethylstyrene,
2,4-dimethylstyrene, p-n-butylstyrene,
p-tert-butylstyrene, p-n-hexylstyrene, p-n-octylstyrene, p-n-nonylstyrene, p-n-decylstyrene, p-n-dodecylstyrene, p-m-1-xystyrene, Examples include styrene and styrene derivatives such as p-phenylstyrene, p-nonylstyrene, and 3,4-dichlorostyrene, with single styrene being most preferred.

Examples of other vinyl monomers include ethylenically unsaturated monoolefins such as ethylene, propylene, butylene, and isobutylene; vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromide, and vinyl fluoride; vinyl acetate, Vinyl esters such as vinyl propionate, vinyl benzoate, vinyl acetate, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-octyl acrylate,
Dodecyl acrylate, 2-ethylhexyl acrylate,
stearyl acrylate, 2-chloroethyl acrylate,
Phenyl acrylate, methyl α-chloroacrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, 11in-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate,
α-methylene aliphatic monocarboxylic acid esters such as dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate; acronitrile; Acrylic acid or methacrylic acid derivatives such as methacrylonitrile and acrylamide; Vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, and vinyl isobutyl ether; Vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, and methyl isopropenyl ketone; N- Examples include N-vinyl compounds such as vinylpyrol, N-vinylcarbazole, N-vinylindole, and N-vinylpyrrolidone; vinylnaphthalenes; and the like.

These vinyl monomers may be used alone or may be used in combination to form a copolymer.

In the above-mentioned polymerization method, the polymer composition is dispersed and suspended in a dispersion medium such as water as dispersed particles of a desired particle size by mechanical stirring, and polymerization is performed, but as the polymerization progresses, the dispersed particles become sticky. Therefore, it is necessary to prevent the particles from coalescing into large particles, and a dispersion stabilizer is used for this purpose.

The materials used as such dispersion stabilizers are generally classified into water-soluble polymeric substances and fine powders of poorly soluble inorganic compounds. Water-soluble polymeric substances include gelatin, starch, polyvinyl alcohol, and others. , sparingly soluble compounds include sparingly soluble salts such as barium sulfate, calcium sulfate, barium carbonate, calcium carbonate, calcium phosphate, inorganic polymer substances such as talc, clay, silicic acid, diatomaceous earth, metal oxides, and other powders. .

In this invention, a polymer is obtained by polymerizing the polymerizable m-form, but a polymerization initiator may be used during the polymerization. Examples of the polymerization initiator include lauroyl peroxide, benzoyl peroxide, 2,2-monoazobisisobutyronitrile, 2,2-azobis-(2,4-dimethylvaleronitrile), orthochlorobenzoyl peroxide, Orthomethoxybenzoyl peroxide is mentioned.

Examples of the coloring agent used in this invention include the following pigments and dyes.

Black pigments carbon black, acetylene black, lamp black, aniline black.

Yellow pigment yellow lead, zinc content, cadmium yellow, yellow iron oxide, mineral fast yellow, nickel titanium yellow, nabels yellow, naphthol yellow S1 Han+y-Yellow G1 Hansa Yellow 10G1 Benzidine Yellow G1 Benzidine Yellow GR, Quinoline Yellow Lake, Permanent yellow NCG1 tartrazine lake.

Orange pigment red yellow lead, molybdenum orange, permanent orange GTR, pyrazolone orange, palkan orange,
Indanthrene Brilliant Orange RK, Benzidine Orange G1 Indanthrene Brilliant Orange GK
.

Red pigment red pigment, cadmium red, red lead, mercury cadmium sulfide, permanent red 4R.

Lysol Red, Pyrazolone Red, Wading Red Calcium Salt, Lake Red D1 Brilliant Carmine 6B1 Eosin Lake, Rhodamine Lake B, Alizarin Lake, Brilliant 1 to Carmine 3B.

Purple pigment Manganese Purple, Fast Violet B1 Methyl Violet Lake.

Blue pigments: navy blue, cobalt blue, alkaline blue lake 1. Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, phthalocyanine blue partially chlorinated product, fast sky blue, indane strenblue-B
O2 Green pigment chrome green, chromium oxide, pigment green B1
Malachite Green Lake, Fanal Yellow Green.

white pigment Zinc white, titanium oxide, antimony white, lead sulfide.

Extender pigments Palite powder, barium carbonate, clay, silica, white carbon, talc, alumina white.

Various dyes (basic, acidic dispersion, direct dyes, etc.) Nigrosine, methylene blue, rose bengal, quinoline yellow, ultraman blue, etc.

In order to improve the properties of other toners, magnetic powder,
A conductive agent, a charge control agent, a fluidizing agent, etc. can also be added as appropriate.

Examples of magnetic powder include fine powders of conventionally known magnetic materials, such as triiron tetroxide (Fe: +04), iron sesquioxide (γ-Fe
203), iron zinc oxide (ZnFe204)
, iron yttrium oxide (Y3 Fe s 0+2 ),
Iron cadmium oxide (Cd FQ 204>), iron gadolinium oxide (Gd 3 Fe s 012 ), steel oxide (Cu Fe z O4), lead iron oxide (Pb FO12019), iron nickel oxide (Ni
Fe 20a >, neodymium iron oxide (Nd'Fe
03), barium iron oxide (Ba Fe 12019
), magnesium iron oxide (MgFe 20t), W
One or a combination of two or more of ferromanganese oxide (MnFe20.l), lanthanum iron oxide (LaFeO:+), iron powder (F e ), cobalt powder (CO), nickel powder (Ni), etc. is used. Ru. Particularly suitable magnetic material pigments are triiron tetroxide and γ-type iron sesquioxide.

In addition, wax, fatty acids or fatty acid metal salts, silica powder, zinc oxide powder, etc. can also be added.

Furthermore, in the developer of the present invention, it has been confirmed that the transfer efficiency is better when the magnetic toner is triboelectrically charged to a polarity opposite to the polarity applied to the transfer recording paper in the electrostatic transfer process. Nigrosine, monoazo dye, zinc hexadecyl succinate, naph [~1 alkyl ester or alkyl amide of acid, nitrofumic acid, N,N'-tetramethyldiaminebensifone, N,N--tetramethylbenzidine, 1 ~ It is preferable to add a strongly polar substance called a charge control agent in this field, such as riazine or a salicylic acid metal complex.

As properties improving agents such as fluidity of the toner, it is also possible to add and mix, for example, silica, hard resin fine powder, zinc oxide, higher fatty acids, higher fatty acid metal salts, silicone oil, fluorine oil, and the like.

Examples of the conductive agent include, in addition to carbon black, copper iodide, ruthenium oxide, various metal powders, etc., and conductive polymer substances such as boriaacetylene, polypyrrole, and polythenylene.

C) Coating layer made of a polymer or a mixture of a polymer and a coloring agent The second coating layer 3 shown in the drawings is made of a polymer or a mixture of a polymer and a coloring agent on top of the first coating layer 2 by a similar method. A newly formed coating layer consisting of a mixture.

D) If necessary, a third coating layer 4, which is the same as the second coating layer 3, is formed by the same method as the second coating layer 3.

It is possible that various functionalities can be developed from toner having such a multilayer structure. - For example, toner with the following functions can be produced.

For example, in the toner shown in FIG.
As the electrical resistance is low A diagonal (102~109Ω-cn
+), and a material with high electrical resistance (
109 Ω-cm or more) and has a structure in which there are no N holes on the outside, the following characteristics can be provided.

For example, the conductivity of the developing toner can be measured by the measuring method described in column 3 of U.S. Pat. No. 3,639,245.
) and the applied voltage (V-Cm-') as shown in FIG.

As shown by lines 5 and 6 in FIG. 2, the conductivity of the conventional conductive toner and the insulating 1-Henner only change slowly in response to changes in the electric field. For the inventive toner, a certain breakdown field exists in the range of 10@2 to 10'V/cm, as shown by line 7, and the conductivity increases rapidly.

Therefore, using this toner, we decided to perform development with an electric field in area B that is larger than the breakdown point (E'b) shown in Figure 2, and transfer with an electric field in area A that is smaller than the breakdown point. This can solve the drawbacks of conventional one-component processes.

1. In other words, in the conventional -component development process, there was a contradiction in that the toner had to be conductive during development and insulating during transfer, but when the toner of this invention has a layered structure, it becomes electric field dependent. , if the value of the applied electric field is different during development and transfer, the same toner can be used.
It can exhibit both conductive and insulating functions.

Hereinafter, the production of HENNER 1 to HENNER of the present invention and the effects of HENNER 1 will be specifically explained with reference to Examples.

Example 1) Method for producing core particles, 100 parts of styrene 2 parts of 2-2-azobisisobutyronitrile (polymerization initiator) 400 parts of a 0.15% methyl cellulose aqueous solution as a dispersion medium to a homogeneous dispersion having the above composition. A composition of 0.05 part of sodium lauryl sulfate was added, and homomixing was performed at room temperature for 10 minutes at 4ooorpm.

This mixture was degassed and replaced with nitrogen, then heated to 70° C. and polymerized for 6 hours while stirring normally.

The product was particles with an average particle size of 9 μm (particle size distribution varied by ±50% or more). This was classified to obtain core particles with an average particle diameter of 8 μm (dispersion of particle size distribution within ±25%).

2) Production of micro polymer particle aqueous dispersion, styrene 80
Part 2 Ethylhexyl acrylate 15 parts, 11-butyl methacrylate 1.5 parts t-butyl mercaptan 1
5 parts 1.5% sodium lauryl sulfate aqueous solution 200 parts Ammonium persulfate (initiator) 0.2 parts The mixture of the above composition was degassed, replaced with nitrogen, and emulsion polymerized at 60°C for 18 hours to obtain an aqueous dispersion of micro polymer particles. was manufactured.

3) Production of toner, a) Aqueous dispersion of fine polymer particles (solid content 30%) 20
While stirring 0 parts, an aqueous dispersion of conductive carbon black (915 parts of conductive carbon black/300 parts of water uniformly dispersed by high shear stirring) and an aqueous sodium hydroxide solution were added, and the pH was adjusted to >8. was maintained to form a stable and uniform aqueous dispersion.

While continuing to stir this, the core particle slurry (solid content 2
A uniform aqueous dispersion was obtained by adding 200 parts of I)l-(>8 and suppressing the increase in viscosity due to agglomeration and coalescence of fine polymer particles.

While stirring this uniform aqueous dispersion, the inlet temperature was 140 to 16.
Spray drying was carried out at 0°C and outlet temperature 50-70°C.

In this way, the core particles 7j have a first coating layer containing a colorant and having a relatively low electrical resistance.

The particles had an average particle diameter of 10 μm (within 30% variation) and a volume resistivity of 8.2×10 6 Ω-am.

b) The above micro polymer particle aqueous dispersion (solid content 30%) 2
While stirring 00 parts, add 2 parts of carbon black/
A dispersion consisting of 300 parts of water (uniform dispersion obtained by high-shear stirring) and an aqueous sodium hydroxide solution were added to prepare a stable homogeneous aqueous dispersion while maintaining pl-1>8.

Add 200 parts of the particle slurry (solid content 20%) with the first coating layer prepared in step a) above to this, maintain pl-1>8 without stirring, and agglomerate and coalesce the fine polymer particles. Inlet temperature 140-160 while suppressing viscosity increase
℃, outlet temperature 50-70℃, the first coating layer (
A magnetic toner with a multilayer structure with resistance and functionality has been created.

The average particle size of this toner is 11μ, and the variation in particle size is ±
It was within 30%.

4) Image formation, using this toner as a developer, according to Japanese Patent Application Laid-Open No. 55-8495
When an image was formed using a prototype device based on the recording method named LIST method described in 5@, a clear image was obtained.

In addition, among the raw material components in the second step 2), which is similar to the above example, in the production of the micro polymer particle aqueous dispersion,
The emulsifier, sodium lauryl sulfate, was replaced with other substances, such as sodium dodecylbenzenesulfonate, sodium alkylnaphthylenesulfonate, β-naphthalenesulfonic acid pomarin condensate sodium salt, etc., and the other conditions were the same as in the examples. Even if the toner was produced in a process, it was possible to produce a toner with the same effects as in the example.

However, when potassium oleate, sodium oleate, sodium tallowate, etc. are used as emulsifiers, the results are not good.

The aqueous dispersion of micro polymer particles usually needs to be alkaline or neutral; if acidic substances are introduced and the liquid becomes m-based, especially less than pI-15, it becomes unstable and tends to aggregate.

The amount of the emulsifier is suitably a concentration exceeding 0.5%, since there is no effect if the concentration of the emulsifier aqueous solution in the above examples is less than 0.5%.

Effects As explained above, the following effects can be achieved according to items 1 to 3 of this invention.

1) Since the particles are spherical, the toner has good fluidity, and therefore, the toner can be replenished smoothly.

2) Since the particle size distribution of the toner is uniform, the 07M distribution is sharp and the toner has stable charge characteristics.

3) Since the toner has a multilayer structure, it is possible to create a functional toner, which is effective in improving image quality.

[Brief explanation of drawings]

FIG. 1 is an enlarged cross-sectional view of toner particles that schematically shows the structure of the toner of the present invention. FIG. 2 is a correlation diagram between applied electric field and toner conductivity, showing the characteristics of an applied example of the toner of the present invention. , 1... Nucleus particle, 2... First coating layer, 3... Second
Coating layer, 4...Third coating layer, 5...Line indicating the electrical conductivity of the conductive toner, 6... Line indicating the electrical conductivity of the insulating toner, 7... Toners 1 to 1 of the present invention A line showing the conductivity of the patent applicant: Ricoh Co., Ltd. - Agent: Patent attorney: Hidetaka Komatsu Agent: Patent attorney: Hiroshi Asahi Procedural official document (method) April 26, 1980 Commissioner of the Patent Office: Kazu Wakasugi Husband 1, Indication of matter fl. 1982 Patent Application No. 6326 2,
Title of the invention Toner for electrostatic charge development and its manufacturing method Color Name (G74) Rico Co., Ltd. - Representative Hama
1) Hiro 4, Agent 107 (Telephone: 58G-8854) Address: 4-13-5-5 Akasaka, Minato-ku, Tokyo, Date of amended order: April 4, 1980 (Shipping date: April 1982) (Mon. 24th) 6. Drawings subject to amendment

Claims (1)

[Claims] (1) A core particle made of a substantially spherical polymer, a first coating layer provided on the surface of the core particle and made of a mixture of at least a coloring agent and fine polymer particles, and a first coating layer formed on the first coating layer. 1. A toner for electrostatic development, characterized in that it is provided with one or more coating layers consisting of at least polymer particles or a mixture of polymer particles and a colorant. [2] After adding core particles consisting of a substantially spherical polymer and a coloring agent to a fine polymer particle dispersion system under conditions that do not cause aggregation or coalescence of the fine polymer particles, and uniformly dispersing the fine polymer particles, The glass transition temperature (Tg
) A first coating layer made of a mixture of a polymer and a colorant is formed on the surface of the spherical core particles by spray-drying at a temperature above 1.), and further, on the coated surface of the core particles,
A method of forming a new coating layer made of a polymer or a mixture of a polymer and a coloring agent is performed at least once by the same method as for forming the first coating layer, thereby forming a multilayer structure. Method for producing toner for charge development.