JPH0812473B2 - Toner for developing electrostatic image and method for producing the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a toner for developing an electrostatic image and a method for producing the same. More specifically, the present invention relates to a novel toner in which a water-soluble dye is attached to polymer particles. The manufacturing method is related.

(Prior Art) In the field of electrophotography, toner is used for the purpose of making an electrostatic image visible. The toner particles are composed of a composition in which a colorant, if necessary, other compound such as a charge control agent is mixed in a resin medium in a certain particle size range, for example, 5 to 30 μm. As the resin medium, a resin having a desired electroscopic property and binding property, for example, a styrene resin or the like is used, and as the colorant, carbon black or another organic or inorganic color pigment is used. To be done.

The most typical method for producing an electrophotographic toner comprises a step of melt-kneading the above-mentioned resin medium and a colorant, cooling and pulverizing the kneaded composition, and classifying the pulverized material to make it uniform within a certain particle size range. However, the yield of the toner obtained by this pulverization / classification is extremely low, and a large amount of equipment is required for these operations, which makes the manufacturing cost of the toner extremely high. In addition, since the shape of the obtained particles is irregular, the flowability of the toner is generally low, and blocking is likely to occur.

On the other hand, as a method for directly obtaining colored polymer fine particles without including a pulverization step, for example, JP-B-36-10231, JP-B-51-14895, JP-B-53-17735, JP-B-53-1
7736, Japanese Patent Publication No. 53-17737 and Japanese Patent Publication No. 47-51830
As described in Japanese Patent Publication, a method by a polymerization method has been proposed.

These are so-called suspension polymerization methods, in which a polymerization composition containing a polymerizable monomer, a polymerization initiator and a colorant as a component is suspended in an aqueous dispersion medium and polymerized to directly produce a toner. To do. This method has the advantages that the toner particles produced are spherical and have excellent fluidity, and that the manufacturing process is simple and the cost is low.

(Problems to be Solved by the Invention) However, in the method for producing a toner by the suspension polymerization method, the charge control agent is not coordinated in the vicinity of the surface of the particle directly contributing, but is buried in the surface of the particle. Therefore, a large amount of charge control agent is required to obtain the same charging characteristics as compared with the production by the pulverization method.

On the other hand, many charge control agents exhibit a polymerization inhibiting action, and the resulting polymer has a low molecular weight, or the amount of use is limited because the polymerization time is long and the polymerization reaction is not completed. . Further, when the charge control agent is dispersed or dissolved in the polymerization composition, the viscosity of the polymerization composition increases, and there is a problem that the particle size distribution becomes broad when suspension oil droplets are generated. Further, the toner obtained by the suspension polymerization method requires a large amount of a dispersion stabilizer in order to prevent an increase in particle diameter due to coalescence of the oil droplet particles of the polymerization composition suspended and dispersed in the polymerization step. Therefore, the dispersion stabilizer is present on the surface of the produced polymer particles, the humidity dependency becomes high, and the moisture resistance and the chargeability become low.

Therefore, it is an object of the present invention to provide a method for synthesizing a toner having excellent electrophotographic characteristics by the suspension polymerization method, which solves the above-mentioned drawbacks of the conventional toner production method by the suspension polymerization method.

Another object of the present invention is to use a water-soluble dye,
It is an object of the present invention to provide a method for producing a toner for developing an electrostatic charge image, which has excellent charging characteristics and moisture resistance without internally adding a large amount of a charge control agent to a polymerizable composition.

Still another object of the present invention is to provide a toner having a structure in which a water-soluble dye is effectively attached to the surface of polymer particles and having excellent charging characteristics and moisture resistance.

(Means for Solving Problems) In order to solve the above problems, according to the present invention, a polymerizable composition containing a toner property-imparting agent is suspended in an aqueous phase in which a water-soluble polymer is dissolved. Provided is a toner for developing an electrostatic charge image, characterized in that a water-soluble dye is adsorbed on polymer particles obtained by dispersing and polymerizing.

According to the present invention, a polymerizable composition containing a toner property-imparting agent is suspended and dispersed in an aqueous phase in which a water-soluble polymer is dissolved, and polymerized to obtain polymer particles. Provided is a method for producing a toner for developing an electrostatic charge image, which comprises removing the polymer and dyeing the polymer particles in an aqueous solution in which a water-soluble dye is dissolved.

(Function) The present invention uses a water-soluble polymer as a dispersion stabilizer,
Polymerizing a polymerizable composition containing a toner additive such as a colorant by suspension polymerization to obtain polymer particles, and removing an excessive dispersion stabilizer, and dyeing only the polymer particles with a water-soluble dye. Is characterized by.

First, the polymerizable composition is put into an aqueous phase in which a water-soluble polymer is dissolved, and the mixture is stirred by a homomixer homogenizer or the like to generate oil droplet particles having a uniform particle size distribution suitable for a toner, and then a polymerization reaction is performed. . Since these oil droplet particles do not contain a large amount of charge control agent, no inhibiting action is observed during polymerization, the polymerization reaction proceeds smoothly, and polymer particles having a narrow particle size distribution are efficiently produced. The water-soluble polymer is grafted on the surface of the polymer particles and covers the whole. Next, the polymer particles produced from the aqueous phase are taken out, the polymer particles are put into an aqueous solution in which a water-soluble dye is dissolved, and the hydrophilic portion of the polymer substance covering the surface of the polymer particles is charged. The dye is effectively absorbed by the. As described above, in the present invention, the water-soluble polymer on the surface of the toner, which has a high humidity dependency and adversely affects the electrical characteristics of the toner, is effectively covered with the dye, and the dye is exposed on the surface of the toner particle. Thus, toner particles having a good shape and having excellent triboelectric chargeability as well as moisture resistance can be obtained.

As the water-soluble polymer used in the present invention, known ones such as polyvinyl alcohol, methyl cellulose, ethyl cellulose, methyl hydroxypropyl cellulose, gelatin, etc. are used, and 0.5 to 5% by weight, especially 1.5
It is preferable to use 3 to 3% by weight. Further, as the water-soluble dye used in the present invention, direct azo dye, copper complex salt azo dye,
Known water-soluble dyes such as direct dyes such as phthalocyanine dyes, acid azo dyes, acid anthraquinone dyes, acid dyes such as metal complex salt azo dyes and other basic dyes are used. In the present invention, in order to carry out the first-arriving step only on the polymer particles, 0.05 to 0.5% by weight based on the polymerizable monomer.
Can be sufficiently washed with a small amount of the dye, and the amount of expensive charge control agent used can be suppressed.

In the present invention, the monomer used is a radical-polymerizable one, and the produced polymer has the fixing property and the electroscopic property required for the toner. One kind or two or more kinds of combinations are used under the above-mentioned restrictions.

Suitable examples of such a monomer include a monovinyl aromatic monomer, an acrylic monomer, a vinyl ester monomer, a vinyl ether monomer, a diolefin monomer, and a monoolefin monomer. The body etc.

The monovinyl monomer has the formula In the formula, R ₁ is a hydrogen atom, a lower alkyl group or a halogen atom, and R ₂ is a hydrogen atom, a lower alkyl group, a halogen atom, an alkoxy group, an amino group, a nitro group, a vinyl group or a carboxyl group.

Monovinyl aromatic hydrocarbons such as styrene, α-methylstyrene, vinyltoluene, α-chlorostyrene,
Examples thereof include o-, m-, p-chlorostyrene, p-ethylstyrene, sodium styrenesulfonate, and divinylbenzene, which may be used alone or in combination of two or more.

Further, the above-mentioned other monomers include the following.

formula In the formula, R ₃ is a hydrogen atom or a lower alkyl group R ₄ is a hydrogen atom,
Acrylic monomers of hydrocarbons having up to 12 carbon atoms, hydroxyalkyl groups, vinyl ester groups, or aminoalkyl groups, such as acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, acrylic Acid-2-ethylhexyl, cyclohexyl acrylate, phenyl acrylate, methyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, β-hydroxyacrylate, γ-hydroxyacrylate, δ-hydroxybutylacrylate, β-Hydroxymethacrylate, γ-aminopropyl acrylate, γ-N, N′-diethylaminopropyl acrylate, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, etc .; Formula Wherein R is a hydrogen atom or a lower alkyl group, vinyl ester of, for example, vinyl formate, vinyl acetate, vinyl propionate, etc .; Wherein R ₆ is a monovalent hydrocarbon group having up to 12 carbon atoms, such as vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl-n-butyl ether, vinyl phenyl ether, vinyl cyclohexyl ether; Wherein each of R ₇ , R ₈ and R ₉ is a hydrogen atom lower alkyl group or a halogen atom, diolefins, especially butadiene, isoprene, chloroprene, etc .; In the formula, each of R ₁₀ and R ₁₁ is a hydrogen atom or a lower alkyl group, and monoolefins, particularly ethylene, propylene, isobutylene, butene-1, pentene-1, 4-methylpentene-1 and the like; To be

In the present invention, the polymerizable composition may contain, in addition to the above-mentioned polymerizable monomer, a colorant for coloring the toner, for example, a dye or a pigment.

 Suitable examples of color pigments are:

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

Yellow pigment Yellow lead, zinc yellow, cadmium yellow, yellow iron oxide, mineral fast yellow, nickel titanium yellow, navel yellow, naphthol yellow S, Hansa yellow G, Hansa yellow 10G, benzidine yellow G, benzidine yellow GR quinoline yellow Rake, Permanent Yellow NCG, Tartrazine Rake.

Orange pigment Red lead yellow molybdenum, molybdenum orange, permanent orange GTR, pyrazolo orange, vulcan orange, indanthrene brilliant orange RK, benzidine orange G, indanthrene brilliant orange GK.

Red pigment red iron oxide, cadmium red, red lead, mercury cadmium sulfide, permanent red 4R, resole red, pyrazolone red, Watchinglet calcium salt, lake red D, brilliant carmine 6B, eosin lake,
Rhodamine Lake B, Alizarin Lake, Brilliant Carmine 3B, Purple Pigment Manganese Purple, Fast Violet B, Methyl Violet Lake.

Blue pigment Navy blue, cobalt blue, alkali blue lake, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, phthalocyanine blue partially chlorinated, fast sky blue, indanthrene blue B
C.

Green pigments Chrome green, chromium oxide, pigment green B, malachite green lake, fanal yellow green G, white pigments zinc white, titanium oxide, antimony white, zinc sulfide.

Extension pigments Barite powder, barium carbonate, clay, silica, white carbon, talc, aluminum white.

Conventional magnetic material pigments include, for example, iron tetroxide (Fe
₃ O ₄ ), iron sesquioxide (γ-Fe ₂ O ₃ ), zinc iron oxide (ZnFe ₂ O
₄ ), iron yttrium oxide (Y ₃ Fe ₅ O ₁₂ ), cadmium oxide (Cd ₃ Fe ₂ O ₁₂ ), iron oxide copper (CuFe ₂ O ₄ ), iron oxide lead (Pb)
Fe ₁₂ O ₁₉ ), iron magnesium oxide (MgFe ₂ O ₄ ), iron manganese oxide (MnFe ₂ O ₄ ), iron powder, cobalt powder (Co), nickel powder (Ni), etc. are known. Also in this case, any of these known fine powders of magnetic materials can be used.

In the present invention, in addition to the above-mentioned essential components, an additive component which is preferably contained in the toner can be added to the polymerization composition prior to the polymerization. In order to obtain an offset prevention effect, a release agent such as low molecular weight polyethylene, low molecular weight polypropylene, various waxes, silicone oils can be contained. Further, in the present invention, the polymerizable composition may contain an oil-soluble dye such as nigrosine base (C15045), oil black (C126150), and spirone black for the purpose of suppressing the generation of fine particles due to emulsion polymerization. . In the case of the present invention, although not generally required, if desired, in order to adjust the medium specific gravity, surface tension, viscosity, etc., in addition to the above dispersant, NaCl, KCl, Na ₂ SO
Water-soluble salts such as ₄ can also be used.

Examples of the polymerization initiator include those soluble in monomers such as azo compounds such as azobisisobutyronitrile and peroxides such as cumene hydroperoxide, t-butyl hydroperoxide, benzoyl peroxide, and lauroyl peroxide. used.

The ratio of monomer to water can vary considerably, but it is generally preferred to use a weight ratio of 1:99 to 50:50, especially 5:95 to 30:70. If a surfactant is used, it should not be used in such an amount that the suspended particles are of emulsion size. The radical polymerization initiator is preferably used in an amount of 0.1 to 10% by weight, particularly 0.5 to 5% by weight per monomer. The polymerization temperature is generally in the range of 40 to 100 ° C, particularly 50 to 90 ° C, and the polymerization time varies depending on the kind of the monomer, but the time for completing the polymerization is selected from the range of 2 to 20 hours. Is good. Further, according to the present invention, it is easy to control the particle size of the produced polymer particles, that is, the toner particles to be in the range of 1 to 30 μm by performing the polymerization under the above conditions, and the standard deviation thereof is generally 3 Within. Purified particles are separated from the reaction medium, and if necessary, generation operations such as washing are performed,
Dry to toner product. If necessary, the toner particles are sprinkled with carbon black, hydrophobic silica or the like to obtain the final toner.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

(Example 1) Styrene 70 parts by weight n-Butyl methacrylate 30 parts by weight Grafted carbon black (MA-100 manufactured by Mitsubishi Kasei) 5 parts by weight Low molecular weight polypropylene (Viscor 550P manufactured by Sanyo Kasei) 1.5 parts by weight Polymerization initiator (AIBN) 2 parts by weight The above mixture is used as a polymerizable composition, and the polymerizable composition is added to a dispersion medium composed of 400 parts by weight of water and 10 parts by weight of polyvinyl alcohol, and suspended using TK-Homomixer (manufactured by Tokushu Kika Kogyo). After turbid dispersion, ordinary stirring was carried out at 80 ° C. in a nitrogen atmosphere and polymerization was carried out for 5 hours to obtain a suspension containing polymer particles. This suspension was filtered, polymer particles were taken out, and the polymer particles were put into a dyeing bath consisting of 400 parts by weight of water, CIAcid Black 132 0.3 parts by weight and 5 parts by weight of acetic acid, and heated to 80 ° C.
The dyeing operation was performed for 30 minutes. Then, the particles were taken out, washed with warm water, filtered and dried to obtain the toner of the present invention.

This toner was mixed with a ferrite carrier, frictionally stirred, and the toner charge amount measured by the blow-off method was -19.5 μc / g. Also, in order to investigate the distribution of the charging polarity of the toner, a width of 70 mm, a gap of 5 mm, an applied voltage of 150
When an air flow was introduced at 950 mm / sec between parallel electrodes arranged vertically at 0 V and the developer was dropped, toner adhered only to the + side electrode and no toner adhered to the-side electrode. . From this, it can be seen that there are almost no + charged toner particles. Furthermore, this developer is applied to an electrophotographic copying machine DC-
When a copy test was carried out with 1001 (manufactured by Mita Kogyo Co., Ltd.), the image did not have fog and the fine lines were reproduced well,
No toner was scattered inside the copier.

(Example 2) A toner was synthesized by the same operation except that C.1. Acid Black 63 was used as the dye in the dye bath of Example 1. Further, when each test was conducted in the same manner as in Example 1, the toner charge amount was −23.0 μc / g, there was almost no reverse polarity toner, and the chargeability was good. Similarly good results were obtained in the copy test.

(Comparative Example) Before carrying out the dyeing operation with the dye of Example 1, the step of removing the polyvinyl alcohol dissolved in the suspension was omitted, and the solution was directly added to the suspension in which solid particles were present. The dye and acetic acid were added to dye the polymer particles. After that, a toner was obtained in the same manner as in Example 1.

The toner charge amount by the blow-off method was -4.2 μc / g, which was not a sufficient charge amount.

(Comparative Example 2) Polymer particles were obtained in the same manner as in Example 1, except that 100 parts by weight of calcium carbonate was used as a dispersion stabilizer instead of polyvinyl alcohol. Further, the toner particles were dyed by the same dyeing operation as in Example 1, washed with hydrochloric acid to remove calcium carbonate, filtered and dried to obtain a toner. The toner charge amount by the blow-off method was -9.3 μc / g, and a sufficient charge amount was not obtained.

(Comparative Example 3) Styrene 70 parts by weight n-butyl methacrylate 30 parts by weight Grafted carbon black (MA-100 manufactured by Mitsubishi Kasei) 5 parts by weight Low molecular weight polypropylene (Viscor 550P manufactured by Sanyo Kasei) 1.5 parts by weight Polymerization initiator (AIBN) 2 parts by weight Charge control agent (Bontron S-34 Orient Chemical Co., Ltd.) 2
Parts by weight The above mixture is used as a polymerizable composition, and the polymerizable composition is added to a dispersion medium composed of 400 parts by weight of water and 10 parts by weight of polyvinyl alcohol and suspended using TK-Homomixer (manufactured by Tokushu Kika Kogyo). After dispersion, ordinary stirring was performed at 80 ° C. in a nitrogen atmosphere, and polymerization was performed for 5 hours. Polymer particles were filtered from the obtained reaction product, washed and dried to obtain a toner. The toner charge amount by the blow-off method was −4.0 μc / g.

Further, the toner charge amounts of the toners of Examples and Comparative Examples under high humidity (20 ° C., 80%) were measured. The particle size distribution of the toner was also measured using a Coulter counter.

Table 1 shows the measurement results of each test for the toners of Examples and Comparative Examples.

(Effects of the Invention) According to the present invention, by using a water-soluble dye, it is possible to reduce the amount of expensive charge control agent used, and the water-soluble dye adheres to the surface of the produced toner. , Because it effectively covers the water-soluble polymer that adversely affects the toner due to the humidity dependency and exposes the water-soluble dye on the toner surface instead, it has excellent triboelectric charging ability as well as moisture resistance. Toner is obtained. Further, according to the present invention, since a large amount of charge control agent is not added to the polymerizable composition, the particle size distribution of the oil droplet particles generated during suspension becomes sharp, and a toner having a uniform particle diameter can be obtained. .

Claims (2)

[Claims] 1. A polymer particle obtained by suspending and dispersing a polymerizable composition containing a toner property-imparting agent in an aqueous phase in which a water-soluble polymer is dissolved, and polymerizing An electrostatic charge image developing toner characterized by being adsorbed. 2. A polymerizable composition containing a toner property-imparting agent is suspended and dispersed in an aqueous phase in which a water-soluble polymer is dissolved and polymerized to obtain polymer particles. Removed,
A method for producing a toner for developing an electrostatic charge image, comprising washing the polymer particles and then dyeing the polymer particles with the dye in an aqueous solution in which a water-soluble dye is dissolved.