JPH0385547A - Electrostatic charge image developing toner and its manufacture - Google Patents

Abstract

PURPOSE:To adapt the polymerization degree of a resin produced in toner particles to exhibit necessary toner characteristics by using specified 2 kinds of radical polymerization initiator to directly produce the toner particles by suspension polymerization. CONSTITUTION:The toner is manufactured by directly producing by the suspension polymerization of a toner forming composition containing at least a vinyl monomer and a colorant and at least 2 kinds of radial polymerization initiators having half-lives tauA and tauB different from each other and a tauA/tauB ration of 5-10 and a molar ration of 1:9 to 9:1, thus permitting the molecular weight distribution of the resin directly produced by setting polymerization conditions to match the requirements of the various toner characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a toner for developing electrostatic images and a method for producing the same, and more particularly relates to a toner by a suspension polymerization method and a method for producing the same.

(Prior Art) In the field of electrophotography, dry toners are widely used for developing electrostatic images. This dry toner is mixed with a magnetic carrier and used as a two-component developer. When making copies, a magnetic brush of the two-component developer is formed on a developing sleeve equipped with a magnet. A toner image is formed by rubbing against a photoreceptor having an electrostatic image, and this toner image is transferred onto copy paper, and then the toner image is thermally fixed onto the copy paper using a heat roller or the like.

The electrostatic image developing toner is produced by blending a fixing resin with a colorant, a charge control agent, and, if necessary, a release agent, and melt-kneading this composition, pulverizing it, and classifying it.
The classification operation requires a large amount of equipment and labor, and there are also problems such as low yield.

It is already known that toner particles can be produced directly in the polymerization process of a fixing resin, and according to the conventional method, a toner-forming composition containing at least a radical polymerization initiator, a vinyl monomer, and a colorant is used. It is suspended in an aqueous medium and polymerized. According to this method, the particles formed by polymerization C have the advantage of being adjusted to a particle size that can be passed through the toner, but since the fixing resin in the toner particles is formed by suspension polymerization, However, there is a problem in that the molecular weight distribution does not necessarily match the various characteristics and fixing characteristics of the toner.

Recently, Japanese Patent Publication No. 64-11941 discloses that the main component is a vinyl resin obtained by suspension polymerization of vinyl monomers in the presence of a polymerization initiator and a crosslinking agent, and a mold-releasing substance. In the toner for developing an electrostatic image for hot roller fixing, the polymerization initiator is composed of two or more types of polymerization initiators having different half-lives, and among the polymerization initiators, the polymerization initiator has the longest half-life. The half-life at 70°C of A and the polymerization initiator B, which has the shortest half-life, is 8. The ratio of τB, τA/τ8, is 1.
A toner for developing an electrostatic image for heat roller fixing is described, which is characterized in that the toner has a particle size of 0 to 10'.

(Problems to be Solved by the Invention) The above proposal proposes that a polymerization initiator with a short half-life be used as a rapid-initiating system, and a polymerization initiator with a long half-life as a slow-initiating system to produce a resin. Molecular weight distribution or dispersion M
This method is recognized as being significant in that it attempts to increase w/Ms and prevent toner offset, but this method polymerizes the fixing resin for toner alone, and the fixing resin monomer There is a problem in that it is not yet applicable to the production of polymerized toners in which toner particles are formed simultaneously with polymerization by polymerizing in the coexistence of colorants and other toner ingredients.

That is, when directly synthesizing toner by suspension polymerization, the appropriate time for polymerization is in the range of 3 to 10 hours.
It is practically difficult to complete the polymerization in a shorter time than that, and industrialization is difficult to achieve a longer time than that.

As in the prior art, in combination polymerization initiators in which τ^/τ♂ is in the range of 10 to 106, the slow initiation system does not participate in the production of high molecular weight components, or the fast initiation system contributes almost nothing to the polymerization. Therefore, it is not suitable for direct synthesis of toner by suspension polymerization method.

Therefore, an object of the present invention is to provide a method for directly synthesizing toner by suspension polymerization, in which polymerization conditions can be set so that the molecular weight distribution of the resulting resin matches the required properties of the toner. .

Other objects of the present invention are the combination of low temperature fixing properties, anti-offset properties, anti-blocking properties, anti-shatter properties, and anti-spent properties:
An object of the present invention is to provide an excellent suspension polymerization toner and a method for producing the same.

Another object of the present invention is to provide a method for easily producing a suspension polymerization toner having the above characteristics in a short polymerization operation.

(Means for Solving the Problems) According to the present invention, a composition for forming a toner containing at least a radical polymerization initiator, a vinyl monomer, and a colorant is subjected to suspension polymerization in an aqueous medium. In the method for producing a polymerized toner, radical polymerization initiators are used that have different half-lives, the ratio of the longer half-life to the shorter half-life (τA/τB) is 5 or more and less than 10, and A toner for developing electrostatic images, characterized in that polymerization is carried out using two or more types of initiators in a molar ratio of 1=9 to 9:1, and toner particles are directly produced in the suspension system. A manufacturing method is provided.

According to the present invention, there is also provided a polymerized toner obtained by suspension polymerizing a toner-forming composition containing at least a radical polymerization initiator, a vinyl tea monomer, and a colorant in an aqueous medium, in which the toner is substantially The toner consists of particles that are upper spherical, have a median diameter of 3 to 30 μm, and have a particle size dispersity expressed by D25/D75 of 1.7 or less, and the resin in the toner has a weight molecular weight of 20.0()O to 500. OO
Electrostatic image development characterized by having a gel permeation chromatogram (GPC) having a maximum value of a high molecular weight component at O and a maximum value of a low molecular weight component at a weight molecular weight of 2,000 to 20,000. toner is provided.

(Function) In the present invention, a toner forming composition containing at least a radical polymerization initiator, a vinyl monomer, and a colorant is suspension-polymerized in an aqueous medium, and toner particles are directly produced in this suspension system. let The toner particles produced contain components necessary for toners such as a colorant in addition to a vinyl polymer fixing agent, and are substantially spherical, with a median diameter of 3 to 30 μm, particularly 5 μm, which is suitable for the toner. The particle size is uniformly adjusted to a range of from 20 μm to 20 μm, and the degree of dispersion of the particle size expressed by D 25 / D t5 is 1.7 or less, particularly 1.5 or less, and the particle size is monodisperse or close to it.

In the present invention, during this suspension polymerization, radical polymerization initiators are used with different half-lives, and the longer half-life (τ
The ratio (τA/τ,) of A) and the shorter half-life (τ, ) is 5 or more and less than 10, especially 5 to 8, and the molar ratio of both is 1:9 to 9:1, especially 3 Near to 7:3 2
Polymerization is carried out using an initiator of ft1 or more. As already pointed out, in the direct synthesis of toner by suspension polymerization,
Although the polymerization time is limited to about 3 to 10 hours, both the initiator with a short half-life and the initiator with a long half-life can be effectively involved in the polymerization of the monomer during the above polymerization time. Therefore, it is essential to select a combination in which the ratio of τA/τB falls within the above range. To explain in more detail, initiating polymerization and forming low molecular weight components, it is necessary to use an initiator with a τb of 10 to 100 minutes, especially 20 to 80 minutes, at the polymerization temperature, while in forming high molecular weight components, If an initiator with a half-life (τA) of 5 times or more and less than 10 times the half-life (τB) of the initiator is used, polymerization of high molecular weight components can be effectively performed even within a relatively short polymerization time. That's why it's happening.

The short half-life initiator and the long half-life initiator are used by adding them to the polymerization system in so-called catalytic amounts, but there are limits to the ratio of the amounts used, and when used in the above ratio, Both initiators can be efficiently involved in the polymerization, and the polymerization degree distribution of the resulting resin can be optimized for the required toner properties.

That is, the resin in the toner according to the present invention has a weight molecular weight of 20
,000 to 500.000, and a maximum value of low molecular weight components in the weight molecular weight range of 2,000 to 20,000. This high molecular weight component has anti-offset, anti-blocking, anti-shatter properties,
The low molecular weight component contributes to spent resistance, while the low molecular weight component contributes to low temperature fixability, resulting in an optimal combination of toner properties. From the viewpoint of the balance of various properties, it is preferable that the high molecular weight component is present in an amount of 10 to 90%, particularly 30 to 70%, and the low molecular weight component is present in an amount of 90 to 10%, particularly 70 to 30%, based on the peak area (weight).

In this specification, D2B*07B represents a particle diameter corresponding to 25% and 75% of the total volume of all toner particles.

(Preferred Embodiment) The radical polymerization initiator used in the present invention is a radical polymerization initiator known per se, such as an azo compound-based, hydroperoxide-based, peroxide-based, peroxide-based initiator. The short half-life initiator is selected from among the above to satisfy the above-mentioned conditions.
An initiator with a τ3 of 10 to 100 minutes is selected based on , and then a long half-life initiator is selected so that A/τb is 5 or more and less than 10. Suitable combinations of initiators include, but are not limited to:

2.2°-azobisisobutyronitrile/2,2°-azobis(2,4-dimethylvaleronitrile)...τ1
/τ, =5.2.22'-azobis(2-cyclopropylpropionitrile) /2,2'-azobis(4-
methoxy-2,4-dimethylvaleronitrile)...τ
A/τB 8.2.1,1°-azobis(1-cyclohexanecarbonitrile)/benzoyl peroxide...τA
/τB==7.8, benzoyl peroxide/(1-phenylethyl)azodiphenylmethane...τA/τ, =6
．． 0 Vinyl monomers that can form monomer fixing resins are water-insoluble and can form thermoplastic resins that have fixing properties and electrodetection properties. For example, suitable examples are Examples include, but are not limited to, vinyl aromatic monomers, acrylic monomers, vinyl ester monomers, vinyl ether monomers, diolefin monomers, monoolefin monomers, and the like.

As a vinyl aromatic monomer, in the formula, R2 is a hydrogen atom, a lower alkyl group, or a halogen atom, and R2 is a hydrogen atom, a lower alkyl group, a halogen atom, an alkoxy group, a nitro group, or a vinyl group.

vinyl aromatic hydrocarbons such as styrene, α-methylstyrene, vinyltoluene, α-chlorostyrene, o+
.

Formula, 3 CH2= C-Go-0-R4...(2) In the formula, R5
is a hydrogen atom or a lower alkyl group, and R4 is a hydrogen atom, a hydrocarbon group having up to 12 carbon atoms, a hydroxyalkyl group, or a vinyl ester group. Acrylic monomers such as methyl acrylate, ethyl acrylate, acrylic butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, methyl methacrylate, hexyl methacrylate,
2-ethylhexyl methacrylate, ethyl β-hydroxyacrylate, propyl γ-hydroxyacrylate,
δ-hydroxybutyl acrylate, β-hydroxyethyl methacrylate, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, etc.

Formula, CH2=CBoc-Rs...(3)
In the formula, R5 is a hydrogen atom or a lower alkyl group, vinyl esters such as vinyl formate, vinyl acetate, vinyl propionate, etc.

Vinyl ether of the formula, C12ZCH0-Ra... (4) where R6 is a monovalent hydrocarbon group having up to 12 carbon atoms, such as vinyl-n-butyl ether, vinyl phenyl ether, vinyl cyclohexyl ether, etc. .

Diolefins of the formula, wherein each of Ry, Ra, and R9 is a hydrogen atom, a lower alkyl group, or a halogen atom,
Especially butadiene, isoprene, chloroprene, etc.

Formula, IG C:R2=C: -R++
...(6) In the formula, each of R4°, R,, is a hydrogen atom or a lower alkyl group.

monoolefins, especially ethylene, propylene, isobutylene, butene-1, pentene-1,4-methylpentene-1, etc.

Suitable monomers include styrenic monomers, acrylic monomers, styrene-acrylic monomers, and the like.

This monomer can contain a coloring agent, and such coloring agents include various pigments and dyes (hereinafter simply referred to as coloring pigments) for coloring toners.

Suitable examples of colored pigments are:

Black pigments 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 01
Hansa Yellow 10G, Benzidine Yellow 〇, Benzidine Yellow GR, Quinoline Yellow Lake, Permanent Yellow NCG.

Tartrazine rake.

Orange pigment red yellow lead, molybdenum orange, permanent orange GTR, pyrazolo orange, palkan orange, indanthrene brilliant orange RK, benzidine orange G1 indanthrene brilliant orange GK.

Red pigment red pigment Red Garla, Cadmium Red, Red Lead, Mercury Cadmium Sulfide, Permanent Red 4R, Lysole Red, Pyrazolone Red, Watching Red Calcium Salt, Lake Red D, Brilliant Carmiso 6B, Eosin Lake, Rhodamine Lake B1 Alizarin Lake, Brilliant Carmine 3B purple pigment manganese purple, fast violet B1 methyl violet lake.

Blue pigments navy blue, cobalt blue, alkali blue lake, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, phthalocyanine blue partially chlorinated product, first sky blue, indanthremble-BC
.

Green pigment chrome green, chromium oxide, pigment green B1
Malachite Green Lake, Final Yellow Green G0 White pigment zinc white, titanium oxide, antimony white, zinc sulfide.

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

Conventionally, as a magnetic material pigment, for example, triiron tetroxide (Fen
04), iron sesquioxide (1'-Fe203), zinc iron oxide (ZnFezO4), iron yttrium oxide (Y3Fe
sO+2), cadmium oxide (CdFe204), iron gadolinium oxide (GdsFesO+z) % iron copper oxide (C
uFe204), iron oxide complex (PbFetzO+*)
, neodymium iron oxide, (NdFeOs), barium iron oxide (BaFe+zO+s), magnesium iron oxide (M
nFezO4), iron manganese oxide (MnFezO4)
, lanthanum iron oxide (LaFaO,), iron powder (Fe), cobalt powder (Go), nickel powder (Nl), etc., but in the present invention, any of these known fine powders of magnetic materials can be used. can be used.

The quantitative ratio of colorant to water-insoluble monomer can vary quite widely, but - numerically speaking, the ratio of colorant to water-insoluble monomer is between 1:100 and 20:100, especially 3:100. to 1
A weight ratio of 0:100 can be used.

In the present invention, toner auxiliaries known per se may be incorporated into the toner forming composition. Examples of the toner auxiliary agent include a charge control agent and a release agent. Charge control agents include those known per se, such as nigrosine base (CI 5045) and oil black (II:I
261.50), oil-soluble dyes such as spirone black, naphthenic acid metal salts, fatty acid metal soaps, metal-containing complex salt dyes, etc. can be blended, as well as charge-controlling functionalities that can be copolymerized with the vinyl-based carmer. Group-containing water-soluble monomers may be used. Such monomers include sulfonic acid, phosphoric acid, and carboxylic acid type anionic groups, or cationic groups such as primary, secondary, or tertiary amono groups, and quaternary animonium groups. Radical polymerizable monomers having electrolytic groups such as
A suitable example is:

Styrene sulfonic acid, sodium styrene sulfonate,
2-acrylamido 2-methylpropanesulfonic acid, 2
-Acid phosphooxypropyl methacrylate, 2-
Acid phosphooxyethyl methacrylate, 3-chloro 2-acid phosphooxypropyl methacrylate,
Acrylic acid, methacrylic acid, fumaric acid, crotonic acid, tetrahydrotylev, taric acid, itaconic acid, aminostyrene, acrylic diethyl methacrylate, aminopropylacrylate, diethylaminopropylacrylate, γ-
N-(N',N'-diethyl-diethyl)aminopropyl methacrylate, trimethylammoniumpropyl methacrylate.

Polymerization method According to the present invention, a toner-forming composition containing a vinyl monomer and the like is suspended in water. In this case, the concentration of the composition is generally from 1 to 50% by weight, in particular from 5 to 30%! i
It is suitable to adjust the size of the suspended particles to generally 3 to 30 μm5, especially 5 to 20 μm.

A dispersion stabilizer can also be used as necessary to stabilize the suspended state of the toner-forming composition. Such dispersion stabilizers include polymers soluble in the medium, such as
Polyvinyl alcohol, methylcellulose, ethylcellulose, polyacrylic acid, polyacrylamide, polyethylene oxide, poly(hydroxystearic acid)
A dispersion stabilizer such as a copolymer (g-methyl methacrylate-CO-methacrylic acid), a nonionic or ionic surfactant, or an inorganic powder such as calcium phosphate can be used in an amount of 0.1 to 10% by weight in the system. %, especially 0.5 to 5% by weight.

The amount of initiator in the toner-forming composition is from 0.3 to 30% by weight, especially from 0.5 to 1% by weight, based on monomer.
It is preferable to set it to 0% by weight.

During polymerization, the reaction system is replaced with an inert gas such as nitrogen, and the temperature is heated at 40 to 100°C while maintaining the above-mentioned suspended state.
In particular, the polymerization is carried out at a temperature of 50 to 90°C. Of course, mild stirring can also be performed to homogenize the reaction system.

Since the polymerized product after the reaction is obtained in the form of granules having the particle size range described above, the resulting particles are filtered, washed with water or a suitable solvent if necessary, and dried to form toner particles.

The toner particles may contain carbon black, if necessary.
Sprinkle hydrophobic silica etc. to make the final toner.

(Effects of the Invention) According to the present invention, when suspension polymerizing a toner forming composition containing a radical polymerization initiator, a vinyl monomer, and a colorant in an aqueous medium, as a radical polymerization initiator,
2 whose half-lives are different from each other, the ratio of the longer half-life to the shorter half-life (τA/τB) is 5 or more and less than 10, and the molar ratio of the two is 1:9 to 9:1. By using more than one type of initiator, both initiators can effectively participate in the polymerization of the monomer during a relatively short polymerization time, and the required toner properties can be achieved by controlling the degree of polymerization distribution of the resulting resin in the toner particles. It can be optimized for

The toner according to the present invention is substantially spherical, and the median diameter is controlled within a range of 3 to 30 μm, which is suitable for the toner.
Since δ is 1.7 or less, which is monodisperse or close to monodisperse, images are sharp and have excellent resolution, and the resin in the toner has a weight molecular weight of 20,000 to 500.
The maximum value of the high molecular weight component is at ,000, and the weight molecular weight is 2.0.
00 to 20,. Since it has a bimodal GPC with a maximum value of low molecular weight components at 000, this toner has the advantage of having an excellent combination of low-temperature fixing properties, offset resistance, blocking resistance, shatter resistance, and spent resistance. give.

Hereinafter, the present invention will be explained in detail with reference to Examples and Comparative Examples.

(Example 1) 82 parts of styrene, 1 part of 2-ethylhexyl methacrylate
1.5 parts of divinylbenzene, 0.5 parts of divinylbenzene, 8 parts of grafted carbon black, 1 part of Bontron S-34 (manufactured by Orient Chemical Co., Ltd.), and 2 parts of Viscol 550P (manufactured by Sanyo Chemical Industries, Ltd.). In the toner composition, 2.2° azobisisobutyronitrile 1.2,2° azobis(2
, 4) Dissolve 2 parts of dimethylvaleronitrile, mix with 350 parts of an aqueous hydrochloric acid solution containing 10 parts of tricalcium phosphate and 0.5 part of sodium dodecylbenzenesulfonate, and stir at 10,000 rpm with a TK homomixer. Add aqueous sodium hydroxide solution to reduce p)l to 13
Adjusted to. The resulting suspension was charged into a separable flask, and the polymerized product was polymerized at 70° C. for 8 hours under a nitrogen stream, and the polymer was thoroughly washed with dilute hydrochloric acid and distilled water and dried to obtain a toner.

When the particle size distribution of the obtained toner was measured using a Coulter counter, the volume-based median diameter was 11.2.
In μm, the particle size dispersity D 2S/D 71 is 1.
It was 53. In addition, the molecular weight characteristics by GPC are M w
/ M s is 16 and 36.5X 10' and 1.15x
It had a peak value at 10'.

Next, 0.21% part by weight of hydrophobic silica is mixed with 100 parts by weight of the obtained toner to prepare a toner composition, and a ferrite carrier having an average particle size of 90 μm and a toner concentration of 4.0% are prepared.
0%, and a 20,000-sheet printing durability test was conducted on a modified electrophotographic copying machine DC-1205 (manufactured by Sanda Kogyo Co., Ltd., trade name) with a surface temperature of the fixing roller of 185°C, and the fixing performance and offset resistance were We evaluated gender, etc.

Regarding fixing properties, a transfer paper with a toner image formed thereon is passed through and fixed, an adhesive tape is pressed against the formed fixed image ε and then peeled off, and the fixed image before and after peeling is determined. The concentration was determined by measurement using a reflection thermometer (manufactured by Tokyo Electric Power Co., Ltd.), and was evaluated by calculating the concentration. Further, offset resistance was evaluated based on whether an offset phenomenon occurred during continuous copying.

Furthermore, regarding the blocking resistance and spent resistance of the toner, the blocking resistance is determined by placing 20 g of toner in a glass cylindrical cylinder with an inner diameter of 26.5 mm in an oven at 60°C.
Place an ioog weight on the toner and leave it for 30 minutes, then remove the cylinder and evaluate whether the toner crumbles. Spent resistance is determined by the amount of toner adhered to the carrier after the printing durability test. evaluated. The results are shown in Table-1.

(Example 2) 70 parts of styrene, 10 parts of methyl methacrylate, 19 parts of butyl acrylate, 1 part of ethylene glycol dimethacrylate, 5 parts of Permanent Red 4R, Bontron E
-84 (manufactured by Orient Chemical Co., Ltd.) 1 part, Viscole 5
50P (manufactured by Sanyo Kabo Industries Co., Ltd.), 1 part of 1.1° azobis(1-cyclohexanecarbonitrile and 1 part of benzoyl peroxide) were dissolved in the same manner as in Example 1. A toner was obtained by suspension polymerization. However, the polymerization temperature was 90°C.

When the particle size distribution of the obtained toner was measured using a Coulter counter, the volume-based median diameter was 10.9.
In μm, the particle size dispersity (D 2s/D 75) is 1.
It was 48. In addition, the molecular weight characteristics by GPC are M w
/ M N is 12 and 19.3X 10' and 1.04x
It had a peak value at 10'. Then, a printing durability test was conducted in the same manner as in Example 1, and each item was evaluated. The results are shown in Table-1.

(Comparative Example 1) A toner was obtained in exactly the same manner as in Example 1, except that 3 parts of 2,2° azobisisobutyronitrile was used as a polymerization initiator.

When the particle size distribution of the obtained toner was measured using a Coulter counter, the volume-based median diameter was 12.0μ.
m and the particle size dispersity (D 25/D 7%) is 1.59
Met. In addition, the molecular weight characteristics by GPC&: are M w
/Ms was 5 and had a peak value at 5.48×10′. Then, a printing durability test was conducted in the same manner as in Example 1, and each item was evaluated. The results are shown in Table-1.

(Comparative Example 2) As a polymerization initiator, 1. Other than using 1 part of l゛azobis1-cyclohexanecarbonitrile) and 2 parts of 2.2° azobis(4-methoxy2,4 dimethylvaleronitrile),
A toner was obtained in exactly the same manner as in Example 1. However, since there was still a monomer odor 8 hours after the start of polymerization, the polymerization was continued, and it took 25 hours to complete the polymerization.

When the particle size distribution of the obtained toner was measured using a Coulter counter, the volume-based median diameter was 12.5μ.
m, and the particle size dispersity (D 2!l/D ya) is 1.
It was 71. In addition, the molecular weight characteristics by GPC are M w
/ M N is 8 and 25.5X 1α4 and 0.98X
It had a peak value at 10'. Then, a printing durability test was conducted in the same manner as in the examples, and each item was evaluated. The results are shown in Table-1.

(Comparative Example 3) The procedure was exactly the same as in Example 1, except that 1 part of 2.2° azobisisobutyronitrile and 2 parts of 2,2° azobis(2-cyclopropylprobionitrile) were used as polymerization initiators. I got toner. However, to complete the polymerization, 1
It took 6 hours.

When the particle size distribution of the obtained toner was measured using a Coulter counter, the volume-based median diameter was 12. f
In μm, the particle size dispersity (D25/D?S) is 1.
It was 61. In addition, the molecular weight characteristics by GPC are M w
/ MN is 13 and 21.5X 10' and 2.50
It had a peak value at xIQ'. and,
A printing durability test was conducted in the same manner as in the examples, and each item was evaluated. The results are shown in Table-1.

(Comparative Example 4) Completely the same as Example 1 except that 0.1 part of 2,2° azobisisobutyronitrile and 3 parts of 2,2° azobis(2,4 dimethylvaleronitrile) were used as polymerization initiators. A toner was obtained in the same manner.

When the particle size distribution of the obtained toner was measured using a Coulter counter, the volume-based median diameter was 11.3μ.
Dispersity of particle size in m (D 211/D 75) C1.
It was 55. In addition, the molecular weight characteristics by GPC are M w
/ M s is 7 and 8.82x 10' and 2.01x
It had a peak value at 10'. Then, a printing durability test was conducted in the same manner as in Example 1, and each item was evaluated. The results are shown in Table-1.

As is clear from Table 1, according to the method of the present invention,
It can be seen that a toner with excellent properties can be directly produced in a short time by the suspension polymerization method. In addition, those using initiators that are out of the scope of the present invention may have poor polymerization time, fixing properties, offset resistance, blocking resistance, spent resistance,
It can be seen that favorable results cannot be obtained due to some restrictions in various characteristics such as particle size characteristics.

Claims (2)

[Claims] (1) In a method for producing a polymerized toner, which comprises suspending and polymerizing a toner-forming composition containing at least a radical polymerization initiator, a vinyl monomer, and a colorant in an aqueous medium, as the radical polymerization initiator, The half-lives are different from each other, and the ratio of the longer half-life to the shorter half-life (τ_A/τ_B
) is 5 or more and less than 10, and the molar ratio of both is 1:9
A method for producing a toner for developing an electrostatic image, characterized in that polymerization is carried out using two or more types of initiators in a ratio of 9:1 to 9:1, and toner particles are directly produced in the suspension system. (2) A polymerized toner obtained by suspension polymerizing a toner-forming composition containing at least a radical polymerization initiator, a vinyl monomer, and a colorant in an aqueous medium, wherein the toner is substantially spherical and The toner consists of particles having a volume-based median diameter of 3 to 30 μm and a dispersity of particles 1 expressed by D_2_5/D_7_5 of 1.7 or less, and the resin in the toner has a weight molecular weight of 20,000 to 500.0.
The maximum value of the high molecular weight component is 00, and the weight molecular weight is 2,000.
A toner for developing an electrostatic image, characterized in that it has a gel permeation chromatogram having a maximum value of low molecular weight components between 20,000 and 20,000.