JP3449445B2 - Wet developer - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wet developer in which pigment-containing copolymer resin particles are dispersed in an electrically insulating dispersion medium, and is suitable for electrophotography, electrostatic printing and electrostatic recording. It relates to a wet type developer.

[0002]

2. Description of the Related Art Generally, a wet type developer is one in which pigment molecules are dispersed in an electrically insulating dispersion medium. However, the development of an electrostatic latent image in electrophotography or the like is performed by dispersing the pigment particle surface and the electrically insulating dispersion. Since it is due to the electric double layer based on the electrification at the contact surface with the medium, even if the pigment is selected from the hue, etc., the developing method is specified by the charge of the pigment particles themselves, and moreover, the development method is different for each pigment. There is a problem that the charging properties are different.

Therefore, it has been attempted to add a charge control agent to adsorb it on the surface of the pigment and adjust the chargeability of the pigment particles in the developer. However, the charge control agent such as metal soap is an aliphatic hydrocarbon. Since it is soluble in an electrically insulating dispersion medium such as, the charge control agent is easily desorbed from the surface of the pigment particle, and when the pigment concentration is increased, the pigment particle precipitates or aggregates, etc. There is a problem that deterioration over time occurs and the pigment concentration cannot be increased.

The applicant first used an olefinic resin having a carboxyl group or an ester group as a resin, and heat-dissolved it in a solvent having a high temperature dependency in solubility with respect to the resin, for example, a resin solution. After that, the resin solution is cooled to precipitate resin particles, and if necessary, the solvent is replaced with an electrically insulating dispersion medium that does not dissolve the resin, and when a wet developer is used, aggregation does not occur and printing durability is improved. It was found that the wet developer has excellent reproducibility and transferability and has good resolution, and the application was filed earlier.

Further, a copolymer resin composed of at least two kinds of monomer components is used as the resin, and the resin is dissolved in a solvent having a high solubility for the resin, and then the solution is used as an electrically insulating dispersion medium. Mix, precipitate the copolymer resin particles,
Then, it was found that by removing the solvent, it is possible to obtain a wet developer having further excellent dispersion stability.

The copolymer resin used here is a solubility parameter value of a homopolymer (hereinafter referred to as SP) which can be synthesized only from at least one monomer component constituting the resin.
Value) δp ¹ and the SP value δs ¹ of the dispersion medium (δp
With ^{1 -δs 1} = △ ^{δ 1)} is 1.0 or more, the difference between the SP values .delta.s ¹ of SP value .delta.p ² dispersant homopolymers which can be synthesized only from monomeric components other at least one (.delta.p ^{2 -δs 1} = △ ^{δ 2)} is 1.0 or less, and △ difference between [delta] ¹ and ^{△ δ 2 △ (△ δ 1} - △ δ 2) which satisfies the relation of at least 0.5 or higher The deposited copolymer resin particles are characterized by comprising a core portion insoluble in the dispersion medium and an outer edge portion which surrounds the core portion and dissolves or swells in the dispersion medium.

As described above, by designing the constituent components of the resin to be used in consideration of the existence state of the resin particles in the electrically insulating dispersion medium, a wet developer excellent in dispersion stability without aggregation and the like is obtained. It will be possible to obtain.

In general, when carbon black is used as a colorant for a wet type developer, the charge polarity of the toner particles tends to be negative, and it is relatively difficult to obtain toner particles having a positive charge. However, even if it is possible to obtain toner particles having a positive charge, the chargeability thereof is unstable, or because the wettability of the carbon black to the resin or the dispersion medium is low, the dispersion stability is poor, There is a problem in that the developed image has matte roughness and image deletion.

[0009]

SUMMARY OF THE INVENTION The present invention relates to a positively chargeable black wet developer capable of obtaining a smooth and grain-free image during development.

[0010]

The wet developer of the present invention comprises:
A copolymer resin particle comprising at least two kinds of monomer components containing a colorant dispersed in an electrically insulating dispersion medium, wherein the copolymer resin has a core portion insoluble in the electrically insulating dispersion medium; In a wet developer consisting of a core portion and an outer edge portion that dissolves or swells in the electrically insulating dispersion medium, the colorant is carbon black surface-modified with an aliphatic polyamine, and is a copolymer. The resin is characterized by containing a hydroxy group or a carboxyl group.

The wet developer of the present invention is characterized in that the surface-modified carbon black has a pH of 5.0 or less.

First, the relationship between the copolymer resin forming the toner particles and the dispersion medium will be described. It is formed by copolymerizing a copolymer resin and at least two kinds of monomers, and the present inventors have found that the solubility parameter value of a homopolymer composed of only at least one monomer component in the copolymer resin (hereinafter, the difference between the SP values .delta.s ¹ of SP value of) .delta.p ¹ and the dispersion medium ^{(δp 1 -δs 1 = Δδ 1} )
Of 1.0 or more and the SP value δp of a homopolymer composed of only at least one other monomer component
² and the SP value δs ¹ of the dispersion medium (δp ² −δs ¹ = Δ
[delta] ²⁾ is 1.0 or less, and .DELTA..delta ¹ and the difference between ^{Δδ 2 Δ (Δδ 1 -Δδ 2} ) is one which shall have at least 0.5 or more relations.

By having this relationship,
When the copolymer resin particles are dispersed in the dispersion medium, the copolymer resin particles are composed of a core portion insoluble in the dispersion medium, and an outer edge portion that surrounds the core portion and dissolves or swells in the dispersion medium. it can.

Generally, the SP value is known to indicate compatibility or incompatibility between substances. Taking the relationship between a resin and its solvent as an example, the SP value indicates the solubility of the resin in the solvent. It is possible to show the degree, and if the difference in SP value between the two is small, the solubility of the resin in the solvent is large, and if the difference is large, the solubility is small and the resin becomes insoluble. As a method of measuring the SP value of the resin, for example, (1) a dissolution method, that is, a method of estimating from the SP value of a solvent that dissolves the resin (H. Burrel
l, Official Digest, 27 (369), 726 (1950)), (2) Swelling method, that is, for resins that are difficult to dissolve, a method of estimating from the SP value of the solvent that maximizes the degree of swelling (same as above) ,
(3) A method of obtaining from the intrinsic viscosity of the resin, that is, the intrinsic viscosity of the resin in the solvent shows the maximum value when the SP value of the resin and the SP value of the solvent match. Therefore, a method of dissolving the resin in a solvent having various SP values, measuring the intrinsic viscosity of each, and estimating the SP value of the resin from the solubility parameter value of the solvent that gives the maximum value as the intrinsic viscosity (HA
hmed, M, Yassen, J.Coat.Technol., 50,86 (1970), WRSo
ng, DWBrownawell, Polym.Eng.Sci., 10,222 (1970)),
(4) Method of obtaining from molecular attractive force constant, that is, method of obtaining from molecular attractive force constant (G) and molar volume (V) of each functional group or atomic group constituting the resin molecule by the formula SP value = ΣG / V ( DASmall, J.Appl.Chem., 3,71, (1953), K.
L. Hoy, J. Paint Technol., 42, 76 (1970)) is known.

Hereinafter, in the present invention, the SP value of the resin is the value obtained by the molecular attraction constant, and the SP value of the solvent is Hildebrand-Scatchard's solution theory (JHHildebrand, RLScott, "The Solubilit.
y of Nonelectrolytes '' 3rd Ed., Reinhold Publishing
cop., New York (1949), G. Scatchard, Chem. Rev., 8,321
It is obtained by considering the attractive force between molecules based on (1931), and SP value (δ) = (ΔE _v / ΔV ₁ ) ^1/2 (where ΔE _v : evaporation energy, V ₁ : molecular volume, ΔE
_v / V ₁ : cohesive energy), and in the present invention, KLHoy, “J. Paint Technol., 42, 76 (197
The value at 25 ° C. described in 0) is used.

Taking the case where the resin is dissolved in a solvent as an example, the relationship between the SP values of the resin and the solvent will be described. Polystyrene having an SP value of 9.1 has an SP value of 9.1.
Is very soluble in tetrahydrofuran and has an SP value of 8.5 to 9.3 and is soluble in solvents.
It is completely insoluble in n-hexane with a value of 7.3. In this way, the state of the resin in the solvent can be estimated by observing the difference between the SP values of the resin and the solvent.

Further, the resin particles can be precipitated by dissolving the resin in the good solvent in a relatively dilute state, adding the solution to the poor solvent, and removing the good solvent. However, it is thought that this is a resin that was present in a single solvent in a good solvent and in a state where the molecular chain was extended, but in the poor solvent, the molecular chain shrinks, becomes a particle, and precipitates. it can. Therefore, the poor solvent should be a solvent having a difference in SP value such that the resin swells, or S
The difference in P value is large, and the state of particles in the solvent differs depending on whether the resin is a completely insoluble solvent. Moreover, in general, the larger the weight average molecular weight of the resin, the larger the particle size of the resin particles formed.

Although there is such a general relationship between the resin and its solvent, the present inventors have used a copolymer resin as the resin, and have its particles in a solvent having a specific SP value. It has been experimentally found that when present in the copolymer resin, the particle size of the precipitated resin particles changes proportionally as the ratio of the monomer composition in the copolymer resin changes.

In examining the law, a copolymer resin containing at least two kinds of monomer components is
By considering it as a homopolymer composed only of at least one monomer component and a homopolymer composed only of other at least one monomer component, the solubility of each homopolymer in a solvent causes It was found that the dissolution state of the copolymer resin in the inside can be regulated.

Based on the above consideration, the present invention relates to the relationship between the copolymer resin particles and the dispersion medium: (1) SP value δp of a homopolymer composed of at least one monomer component in the copolymer resin. ¹ and SP value of dispersion medium δ
The difference Δδ ^{1 from} s ¹ is 1.0 or more, preferably 1.5 or more, and (2) the SP value δp ^{2 of the} homopolymer composed of only at least one other monomer component and the SP of the dispersion medium. the difference .DELTA..delta ² between the value .delta.s ¹ is 1.0 or less, preferably in the range of 0.5 ≦ Δδ ¹ ≦ 1.0, and (3) thereof, the difference delta (.DELTA..delta ¹ of .DELTA..delta ¹ and .DELTA..delta ² -Δδ ² ) is defined to be at least 0.5 or more, preferably 1.0 or more, so as to cover the insoluble portion in the solvent defined in (1) and the insoluble portion, which is defined in the above (2). A copolymer resin particle having an outer edge portion composed of a dissolved or swollen portion can be obtained.

Such a shape of the obtained copolymer resin particles is such that the portion insoluble in the dispersion medium is incompatible with the dispersion medium,
Further, as a result of the portion that dissolves or swells in the dispersion medium having an affinity with the dispersion medium, the insoluble portion becomes the core portion and is dissolved,
Or, it has a double-layered particle structure in which the swelling part is the outer edge part, and the particle size increases as the proportion of the swelling part increases, and the particle size decreases as the proportion of the swelling part decreases. It is considered to be a thing. Further, as a component in the copolymer resin, when it is considered to dissolve, the dissolved portion does not contribute to the particle size,
The particle size is considered to depend on the insoluble portion (see Japanese Patent Application No. 6-63062).

Next, the copolymer resin and the dispersion medium in the present invention will be specifically described. The copolymer resin and the dispersion medium are the copolymer resin and the dispersion medium having the above-described relationships, and the thermoplastic resin having a hydroxy group or a carboxyl group is used as the copolymer resin.

At least one kind of the thermoplastic resin having a hydroxy group or a carboxyl group as a monomer component is a carboxyl group-containing monomer such as acrylic acid, methacrylic acid, maleic acid or itaconic acid, or 2-hydroxymethyl acrylate. 2-hydroxymethyl methacrylate, 2-hydroxyethyl acrylate, 2
-Hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl acrylate, 2-hydroxybutyl methacrylate, a hydroxy group-containing monomer such as acrylic alcohol, and further 2-methacryloyloxysuccinic acid, 2- Examples include methacryloyloxyfumaric acid and the like. Further, as the other copolymerization monomer component, the above-mentioned SP value relationship is possessed in relation to the above-mentioned carboxyl group- or hydroxyl group-containing monomer or dispersion medium, and radical polymerization is carried out with the carboxyl group- or hydroxyl group-containing monomer. A copolymer resin having a carboxyl group or a hydroxyl group, for example, 2-ethylhexyl methacrylate, 2-ethylhexyl acrylate, lauryl methacrylate, lauryl acrylate, stearyl methacrylate, stearyl acrylate, hexyl methacrylate, hexyl acrylate, dodecyl methacrylate, dodecyl. Acrylate etc. are mentioned. As a copolymer resin, ASTM
Melt flow rate (MF) specified by D-1238
R) is preferably 1 dg / min to 400 dg / min, more preferably 2 dg / min to 150 dg / min. The range of this MFR value is equivalent to about 60,000 to 250,000, preferably 75,000 to 200,000 when converted to the weight average molecular weight. Further, in each copolymer resin, the ratio of the polymer units that are considered to form a soluble or swelled portion in the dispersion medium and the polymer units that are considered to form an insoluble portion in the dispersion medium, The weight ratio may be 95/5 to 5/95, preferably 95/5 to 15/85.

In the case of copolymer resin particles having three or more polymerized units, the third component is the same as any one of the components forming the soluble or insoluble portion in relation to the SP value of the dispersion medium. If the SP value of the dispersion medium is the same as that of the dispersion medium, it may be regarded as a component equivalent to the SP value of the dispersion medium. It is preferable to select the largest one and the smallest one, and the ratio thereof may be the same as in the case of the above-mentioned copolymer resin composed of two components.

Here, in the case of using the above-mentioned copolymer resin in the present invention, a homopolymer and its SP value (Small method), which serve as an index in relation to the SP value of the dispersion medium, will be described.

Polylauryl methacrylate (8.2),
Polystearyl methacrylate (8.2), polyisobornyl methacrylate (8.2), poly-t-butyl methacrylate (8.3), polyethyl methacrylate (9.1), polymethyl methacrylate (9.3), poly Methyl acrylate (9.7), polyethyl acrylate (9.2), polyacrylonitrile (12.8),
Poly (2-ethylhexyl methacrylate) (7.
7), poly-n-hexyl methacrylate (8.6),
Polymethacrylic acid (9.4), polyacrylic acid (9.
8), poly-n-propyl methacrylate (8.8),
Poly-n-butyl methacrylate (8.7), poly-ethoxyethyl methacrylate (9.0), poly-n-butyl acrylate (8.7), poly-methyl-α-cyanoacrylate (14.0), poly -Methyl-α-chloroacrylate (10.1).

As the electrically insulating dispersion medium, 10 ¹⁰
It has a volume resistance of Ω · cm (25 ° C.) or more, and is used for the purpose of enhancing the electric insulation of the wet developer, and has the above-mentioned relationship regarding the SP value with the copolymer resin. Anything can be used. The SP value of the dispersion medium that can be used is n-hexane (7.
3), n-heptane (7.5), n-octane (7.
5), nonane (7.6), decane (7.7), dodecane (7.9), cyclohexane (8.2), perchlorethylene (9.3), trichloroethane (9.9) and the like. However, liquid aliphatic hydrocarbons are preferable, and liquid n-paraffinic hydrocarbons, iso-paraffinic hydrocarbons, or a mixture thereof, halogenated aliphatic hydrocarbons and the like can be mentioned. Particularly preferred is a branched-chain aliphatic hydrocarbon, such as Isopar G, Isopar H, Isopar K, Isopar L manufactured by Exxon Chemical Co., Ltd.
It is preferable to use Isopar M, Isopar V and the like. The SP values of these trade names are approximate to n-hexane (7.3).

Here, SP in the copolymer resin and the dispersion medium
The relationship between the values will be illustrated. For example, when 2-ethylhexyl methacrylate-methacrylic acid copolymer resin particles are used as toner particles, the SP value of poly (2-ethylhexyl methacrylate) is 7.7, and the S value of polymethacrylic acid is S.
The P value is 9.4, and n-hexane (SP is used as the dispersion medium.
Using the value 7.3), Δδ ¹ is 9.4-7.3 =
2.1, Δδ ² is 7.7−7.3 = 0.4, and Δ
Since (Δδ ¹ −Δδ ² ) is 1.7, the above relationship is satisfied. In the dispersion medium, the 2-ethylhexyl methacrylate-methacrylic acid copolymer resin particles have a portion derived from the 2-ethylhexyl methacrylate component dissolved or forming an outer edge portion as a swollen portion, and a portion derived from the methacrylic acid component. Can be considered to have a shape in which an insoluble core is formed.

Next, the colorant in the wet developer of the present invention is obtained by reacting carbon black having a pH of 5.0 or less with an aliphatic polyvalent amine, and the surface of the carbon black has an amino group or an amide. It has a group and the like.
As a result, the copolymer resin has reactivity or affinity with the hydroxy group and the carboxyl group in the above-mentioned copolymer resin.

As the carbon black suitable for producing the colorant in the present invention, MA-made by Mitsubishi Kasei Co., Ltd.
100 (pH value 3.5, volatile content 1.5% by weight), the same # 2
400 (pH value 2.0, volatile content 10.0% by weight), same M
A-7 (pH value 3.0, volatile content 3.5% by weight), MOGUL-L (pH value 2.5, volatile content 5.0% by weight) manufactured by Cabot Corporation, REGAL400R (pH value 4) ．
0, volatile matter 3.5% by weight), same MONARCH1300
(PH value 2.5, volatile content 9.5% by weight), same MONAR
CH1400 (pH value 2.5, volatile content 9.0% by weight) and the like can be mentioned.

Regarding the pH value of carbon black, 100 ml of distilled water was added to 10 g of the sample, and after boiling on a hot plate for 10 minutes and cooling to room temperature, the supernatant was separated and the pH of the mud was adjusted to the glass electrode. It is measured with a pH meter.

The volatile content is 950 ± 1 in advance.
Electric furnace for measuring volatile matter held at 0 ° C (JIS-M-88
12) 4)) and baked for 3 to 5 minutes
A sample dried at 105 ± 1 ° C. for 1 hour is placed in a ml crucible with a dropping lid until the height of the layer becomes 2 mm above the line of the lid, and accurately weighed. It is a value obtained by heating for 7 minutes in the electric furnace, cooling to room temperature in a desiccator, weighing, and displaying the weight loss as a percentage of the sample. That is, the volatile content represents a reduced amount of the oxidation compound (carboxyl, hydroxyl, etc.), and this volatile content is considered to quantitatively indicate the amount of hydroxy groups and carboxyl groups existing on the surface of carbon black.

That is, the larger the volatile content, the larger the amount of amine groups introduced by the addition reaction with the aliphatic polyamine, and conversely, the smaller the volatile content, the smaller the amount of amine groups introduced. Therefore, the volatile content is preferably 1.5% by weight or more.

Examples of the aliphatic polyvalent amine to be added to the carbon black include ethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, diethylaminopropylamine and the like. These may be used alone or in combination of two or more.

The proportion of amine varies depending on the type of carbon black or the type of amine used. Generally, when the proportion of amine is small, the charging polarity of carbon black does not change completely positively, and If the ratio is too large, the charge amount becomes too large, and it becomes impossible to obtain a sufficient image density. Therefore, it is desirable that the ratio of the amine to be subjected to the amine treatment is in the range of 3 to 50 parts by weight, preferably 5 to 30 parts by weight, relative to 100 parts by weight of the carbon black.

The addition reaction of carbon black and amines is carried out by adding carbon black and an aliphatic polyvalent amine to an appropriate amount of methyl alcohol and mixing them by a bead mill, a ball mill or the like, and then at a temperature of 120 to 160 ° C. It can be carried out by heating and drying.

Next, the wet developer of the present invention includes a dispersant,
A charge control agent or the like may be added. Since the copolymer resin particles in the present invention themselves have excellent affinity with the dispersion medium,
Although the dispersant is not always necessary, by allowing the dispersant to be present in the step of granulating the copolymer resin particles, the dispersibility of the resin in the good solvent can be improved, and when the resin particles are formed. Since the entanglement of molecular chains is suppressed, it is possible to granulate resin particles having a smaller particle diameter, and to make the particle diameter distribution narrower in submicron units. The wet developer also has a function of stably dispersing the resin particles in the solvent.

Examples of such dispersants include metal soaps such as zirconium naphthenate and aluminum stearate, natural phosphate esters such as lecithin, aliphatic amines, anionic surfactants, cationic surfactants and amphoteric interfaces. Activators, nonionic surfactants and the like are used.

The dispersant may be added in an amount of not more than 10% by weight, preferably not more than 5% by weight, based on the copolymer resin in the granulation step in the step of producing a wet developer described below.
Further, the wet developer may be contained in an amount of 5% by weight or less, preferably 2.5% by weight or less.

A polymer dispersant such as polyhydroxycarboxylic acid ester may also be used. Polyhydroxycarboxylic acid ester is hydroxycarboxylic acid ester H
A polymer of an ester derivative of O—X—COOH, wherein X is a divalent saturated or unsaturated aliphatic hydrocarbon containing at least 12 carbon atoms, or a divalent divalent containing at least 6 carbon atoms. It is an aromatic hydrocarbon and there are at least 4 carbon atoms between the hydroxy and carboxyl groups. Preferable examples of such hydroxycarboxylic acid derivatives include hydroxycarboxylic alkyl esters such as 12-hydroxystearic acid methyl ester and 12-hydroxystearic acid ethyl ester, 1
Examples thereof include metal salts of hydroxycarboxylic acids such as lithium 2-hydroxycarboxylate and aluminum 12-hydroxycarboxylate, as well as hydroxycarboxylic acid amides and hydrogenated castor oil.

The polyhydroxycarboxylic acid ester is obtained by polymerizing a hydroxycarboxylic acid ester by partially saponifying it in the presence of a small amount of amines or a catalyst, and its polymerization form is obtained by intermolecular esterification. In addition, it contains various forms such as those obtained by esterification in the molecule.

The polyhydroxycarboxylic acid ester is preferably a 3- to 10-mer hydroxycarboxylic acid ester, which is a light gray brown wax-like substance. The degree of polymerization of polyhydroxycarboxylic acid ester is less than 3,
Alternatively, when it is larger than 10, the resin particles have no compatibility with a dispersion medium such as n-hexane, and the desired particle size distribution of the obtained resin particles cannot be obtained even when used in the granulation step. The addition amount of the polyhydroxycarboxylic acid ester is not particularly limited, but is 0.01 wt% to 200 wt% with respect to the resin weight.
Used in proportion.

In the wet developer of the present invention, as a charge control agent, a metal salt of dialkylsulfosuccinate, manganese naphthenate, calcium naphthenate, zirconium naphthenate,
Cobalt naphthenate, iron naphthenate, lead naphthenate, nickel naphthenate, chromium naphthenate, zinc naphthenate, magnesium naphthenate, manganese octylate, calcium octylate, zirconium octylate, iron octylate, lead octylate, octylate Cobalt, chromium octylate, zinc octylate, magnesium octylate,
Metallic soaps such as manganese dodecylate, calcium dodecylate, zirconium dodecylate, iron dodecylate, lead dodecylate, cobalt dodecylate, nickel dodecylate, chromium dodecylate, zinc dodecylate, magnesium dodecylate, calcium dodecylbenzenesulfonate, Alkylbenzenesulfonates such as sodium dodecylbenzenesulfonate and barium dodecylbenzenesulfonate,
Phospholipids such as lecithin and sehalin, organic amines such as n-decylamine and the like can be preferably added. In particular, transition metal salts of dialkyl sulfosuccinic acids (cobalt, manganese,
It is desirable to use zirconium, yttrium, nickel, etc.). The addition amount may be the minimum amount showing the charge control effect, but is usually 0.01 wt% to 50 wt% in the electrically insulating liquid.

As a fixing agent, various resins soluble in a dispersion medium such as n-hexane, for example, modified or unmodified alkyd resins, ordinary acrylic resins, synthetic rubbers, polyalkylene oxides, polyvinyl acetals (butyral also can be used. Including), vinyl acetate resin and the like can be added.

Next, the method for producing the wet type developer in the present invention will be described. The method for producing a wet developer according to the present invention includes (1) a step of dissolving a copolymer resin in a solvent,
(2) a step of mixing a solution in which the copolymer resin is dissolved with a dispersion medium in the presence of a pigment to granulate the copolymer resin particles (3) a step of removing the solvent.

First, the solvent used in the step (1) is one capable of dissolving the copolymer resin at room temperature (25 ° C.), and is a homopolymer composed of at least one monomer component. SP value δp ^{1 of} the above and a SP value δp ² of a homopolymer composed only of at least one other monomer component.
Solvents having values are preferred. In this case, depending on the constituent components, it may not be in a dissolved or swollen state and may be in an insoluble state as long as the dispersed state of the monomolecular chain is good.

Examples of such a solvent (SP value) include the followings, which may be appropriately selected and used in relation to the SP value. Cyclohexane (8.2), cellosolve acetate (9.4), toluene (8.9), tetrahydrofuran (9.1), methyl ethyl ketone (9.5), cyclohexanone (10.4), acetone (9.6), Dioxane (10.1), ethyl cellosolve (10.7), cyclohexanol (11.4), methyl cellosolve (1
1.7), isopropyl alcohol (11.4), ethanol (12.8), methanol (14.5).

The dispersant is added in the solution in an amount of 0.3% by weight to
If it is contained in the range of 0.5% by weight, the resin can be dispersed well. Further, the amount of the copolymer resin dissolved in the solvent can be arbitrary, but if the resin ratio is too high, the resin particles may come into contact with each other in the precipitation step of the resin particles, and a gelled mass may be formed. It is recommended to prepare a dilute solution of 1 to 80% by weight, preferably 5 to 10% by weight.

Next, in the granulation step of (2), (1)
The solution prepared in 1. is mixed with the above-mentioned dispersion medium. At this stage, the pigment is added to the resin solution or the dispersion medium,
When the resin is granulated in the presence of the pigment, the pigment can be included in the copolymer resin particles. At that time, the resin molecular chains dispersed in the solution are entangled to form a pigment by being added to a dispersion medium that is a poor solvent, and the particles are entangled to form a resin particle surface. Is a dissolved or swollen portion in the copolymer resin, and even when the pigment is contained, the pigment does not come into contact with each other and the dispersion stability can be excellent.
The resin particles thus obtained have a particle size of 0.1 μm to
The thickness is 100 μm.

The solvent used for preparing the resin solution is preferably removed by decantation, an evaporator or the like from the viewpoint of granulating property. In addition, in order to adjust the particle size of the resin particles, a ball mill, attritor,
The particles may be further pulverized by using a sand grinder, a kedi mill, a triple roll or the like.

The particle size of the pigment contained in the copolymer resin particles is 0.1-100 μm in the secondary aggregation state.
m of the copolymer resin particles can be used.
It can be included up to 0% by weight, preferably up to 75% by weight.

The particle size of the copolymer resin particles in the present invention is usually appropriately adjusted within the range of 0.1 μm to 100 μm. The content of the copolymer resin particles in the wet developer may be 0.01% by weight to 80% by weight, preferably 0.1% by weight to 50% by weight. The content can be increased as compared with the developer.

The copolymer resin particles in the present invention have a portion insoluble in a dispersion medium as a nucleus and a portion having an affinity for the dispersion medium as an outer edge portion in a wet developer, and have a surface affinity with the dispersion medium. Thus, even if the particle concentration is increased, aggregation, precipitation, etc. do not occur, and the dispersion stability is excellent.

[0054]

The present invention uses carbon black having an amino group or an amide group on the surface as a coloring agent, and
When the copolymer resin forming the toner particles contains a hydroxy group or a carboxyl group, the adsorption of the resin can be made stronger, and the dispersion stability without image deletion can be improved, and the development can be performed. The image of time can be smooth and free of roughness.

Further, by making the copolymer resin excellent in affinity with the dispersion medium, the wettability with respect to the dispersion medium is improved and the dispersion stability of the toner particles can be made excellent.

Next, production examples of the colorant in the present invention will be shown.

[Colorant (1) Production Example] Hexamethylenediamine (manufactured by Tokyo Kasei Co., Ltd.) in 75 parts by weight of methanol.
Dissolve 3.0 parts by weight of MA-100 (Mitsubishi Kasei Co., Ltd.)
15 g of carbon black manufactured by the present invention and having a volatile content of 1.5%) is added to form a slurry, and the mixture is stirred with a bead mill for 3 hours.
The colorant (1) was obtained by filtering the slurry and heating and drying the obtained colorant in a 140 ° C. oven and pulverizing.

Colorants (2) to (13) shown in the table below were obtained in the same manner as in Colorant (1).

Carbon black used for producing the colorant,
The pH, the amount of volatile matter, the type of amine, and the amount added are shown in Table 1 below. In addition, MOGUL-L used for processing
(Manufactured by Cabot Co., Ltd.) and REAGAL400R (manufactured by Cabot Co., Ltd.), and all amines used for the treatment are manufactured by Tokyo Kasei Co., Ltd.

[0060]

[Table 1]

The present invention will be described below with reference to examples. In the examples, "part" means part by weight and "%" means% by weight.

[0062]

Example 1 2-Ethylhexyl methacrylate / methacrylic acid (copolymerization ratio = 95/5) 1.25 parts Colorant (1) 1.50 parts Zirconium naphthenate (Japan Chemical Industry Nikka Naphtex Zr, manufactured by Co., Ltd .... 25 g of a composition consisting of 2.50 parts of tetrahydrofuran and 30 g of tetrahydrofuran
After being dissolved in the solution, it was dispersed at room temperature using an ultrasonic homogenizer (Nippon Seiki Seisakusho Co., Ltd., US-300T), followed by Isopar G (Exxon Chemical Co., Ltd.) at room temperature.
(Manufactured by Mitsui Chemical Co., Ltd.) was added while irradiating an ultrasonic homogenizer, then only tetrahydrofuran was removed using an evaporator, and then the ultrasonic homogenizer was irradiated again to obtain a black wet toner.

This wet toner was diluted with Isopar G,
The toner concentration was adjusted to about 1% by weight to obtain a wet type developer (1), which was used in the following developing process.

The developing process is carried out by using electrostatic recording paper (DSscan Seiko Denshi KK, Seiden Plotter EP-4010).
Various electrostatic patterns having a surface charge of 150 V to 20 V were formed on the (for use)), and the wet developer (1) prepared above was used to develop and print with a roller developing machine. The obtained images were evaluated visually.

Further, in order to evaluate the electrophoretic property as a toner characteristic, 237 HIGHVOLTAGE S
OUR MEASURE UNIT (KEITHLE
Y company) is used, the distance between the electrodes is 1 cm, and the electrode area is 5.0 cm.
Wet type developer was filled between brass electrodes of × 4.5 cm, 1000 V voltage was applied between both electrodes, initial current value was measured, 60
The current value after the second was measured, and the current value (Q / m, unit μC / g) per weight of the toner attached to the electrode was measured. The difference (ΔI, unit%) between the initial current value and the current value after 60 seconds and the Q / m value affect the electrophoretic property of the toner.

Table 2 shows the respective evaluation results.

[0067]

[Example 2] 2-ethylhexyl methacrylate / methacrylic acid (copolymerization ratio = 95/5) 1.25 parts colorant (2) 1.50 parts zirconium naphthenate (Japan Chemical Industry Nikka Naphtex Zr, manufactured by Co., Ltd .... 25 g of a composition consisting of 2.50 parts of tetrahydrofuran and 30 g of tetrahydrofuran
After being dissolved in the solution, it was dispersed at room temperature using an ultrasonic homogenizer (Nippon Seiki Seisakusho Co., Ltd., US-300T), followed by Isopar G (Exxon Chemical Co., Ltd.) at room temperature.
(Manufactured by Mitsui Chemical Co., Ltd.) was added while irradiating an ultrasonic homogenizer, then only tetrahydrofuran was removed using an evaporator, and then the ultrasonic homogenizer was irradiated again to obtain a black wet toner.

After preparing the wet type developer (2) in the same manner as in Example 1, the development evaluation and the toner characteristic evaluation are performed in the same manner.
The results are also shown in Table 2.

[0069]

[Example 3] 2-Ethylhexyl methacrylate / methacrylic acid (copolymerization ratio = 95/5) 1.25 parts Colorant (3) 1.50 parts Zirconium naphthenate (Japan Chemical Industry Nikka Naphtex Zr, manufactured by Co., Ltd .... 25 g of a composition consisting of 2.50 parts of tetrahydrofuran and 30 g of tetrahydrofuran
After being dissolved in the solution, it was dispersed at room temperature using an ultrasonic homogenizer (Nippon Seiki Seisakusho Co., Ltd., US-300T), followed by Isopar G (Exxon Chemical Co., Ltd.) at room temperature.
(Manufactured by Mitsui Chemical Co., Ltd.) while being irradiated with an ultrasonic homogenizer, and then only tetrahydrofuran was removed using an evaporator, and then the ultrasonic homogenizer was irradiated again to obtain a black wet toner.

After preparing the wet type developer (3) in the same manner as in Example 1, the development evaluation and the toner property evaluation are performed in the same manner.
The results are also shown in Table 2.

[0071]

Example 4 2-Ethylhexyl Methacrylate / Methacrylic Acid (Copolymerization Ratio = 95/5) 1.25 Parts Colorant (4) 1.50 Parts Zirconium Naphthenate (Japan Chemical Industry) Nikka Naphtex Zr, manufactured by Co., Ltd .... 25 g of a composition consisting of 2.50 parts of tetrahydrofuran and 30 g of tetrahydrofuran
After being dissolved in the solution, it was dispersed at room temperature using an ultrasonic homogenizer (Nippon Seiki Seisakusho Co., Ltd., US-300T), followed by Isopar G (Exxon Chemical Co., Ltd.) at room temperature.
(Manufactured by Mitsui Chemical Co., Ltd.) was added while irradiating an ultrasonic homogenizer, then only tetrahydrofuran was removed using an evaporator, and then the ultrasonic homogenizer was irradiated again to obtain a black wet toner.

After the wet type developer (4) was prepared in the same manner as in Example 1, the development evaluation and the toner property evaluation were performed in the same manner.
The results are also shown in Table 2.

[0073]

[Example 5] 2-ethylhexyl methacrylate / methacrylic acid (copolymerization ratio = 95/5) 1.25 parts colorant (5) 1.50 parts zirconium naphthenate (Japan Chemical Industry Nikka Naphtex Zr, manufactured by Co., Ltd .... 25 g of a composition consisting of 2.50 parts of tetrahydrofuran and 30 g of tetrahydrofuran
After being dissolved in the solution, it was dispersed at room temperature using an ultrasonic homogenizer (Nippon Seiki Seisakusho Co., Ltd., US-300T), followed by Isopar G (Exxon Chemical Co., Ltd.) at room temperature.
(Manufactured by Mitsui Chemical Co., Ltd.) while being irradiated with an ultrasonic homogenizer, and then only tetrahydrofuran was removed using an evaporator, and then the ultrasonic homogenizer was irradiated again to obtain a black wet toner.

After the wet type developer (5) was prepared in the same manner as in Example 1, development evaluation and toner property evaluation were carried out, and the results are also shown in Table 2.

[0075]

[Example 6] 2-ethylhexyl methacrylate / methacrylic acid (copolymerization ratio = 95/5) 1.25 parts colorant (6) 1.50 parts zirconium naphthenate (Nippon Kagaku Sangyo Nikka Naphtex Zr, manufactured by Co., Ltd .... 25 g of a composition consisting of 2.50 parts of tetrahydrofuran and 30 g of tetrahydrofuran
After being dissolved in the solution, it was dispersed at room temperature using an ultrasonic homogenizer (Nippon Seiki Seisakusho Co., Ltd., US-300T), followed by Isopar G (Exxon Chemical Co., Ltd.) at room temperature.
(Manufactured by Mitsui Chemical Co., Ltd.) while being irradiated with an ultrasonic homogenizer, and then only tetrahydrofuran was removed using an evaporator, and then the ultrasonic homogenizer was irradiated again to obtain a black wet toner.

After the wet type developer (6) was prepared in the same manner as in Example 1, development evaluation and toner property evaluation were carried out, and the results are also shown in Table 2.

[0077]

[Example 7] 2-ethylhexyl methacrylate / methacrylic acid (copolymerization ratio = 95/5) 1.25 parts colorant (7) 1.50 parts zirconium naphthenate (Japan Chemical Industry Nikka Naphtex Zr, manufactured by Co., Ltd .... 25 g of a composition consisting of 2.50 parts of tetrahydrofuran and 30 g of tetrahydrofuran
After being dissolved in the solution, it was dispersed at room temperature using an ultrasonic homogenizer (Nippon Seiki Seisakusho Co., Ltd., US-300T), followed by Isopar G (Exxon Chemical Co., Ltd.) at room temperature.
(Manufactured by Mitsui Chemical Co., Ltd.) was added while irradiating an ultrasonic homogenizer, then only tetrahydrofuran was removed using an evaporator, and then the ultrasonic homogenizer was irradiated again to obtain a black wet toner.

After the wet type developer (7) was prepared in the same manner as in Example 1, development evaluation and toner property evaluation were carried out, and the results are also shown in Table 2.

[0079]

Example 8 2-Ethylhexyl methacrylate / methacrylic acid (copolymerization ratio = 95/5) 1.25 parts Colorant (8) 1.50 parts Zirconium naphthenate (Japan Chemical Industry Nikka Naphtex Zr, manufactured by Co., Ltd .... 25 g of a composition consisting of 2.50 parts of tetrahydrofuran and 30 g of tetrahydrofuran
After being dissolved in the solution, it was dispersed at room temperature using an ultrasonic homogenizer (Nippon Seiki Seisakusho Co., Ltd., US-300T), followed by Isopar G (Exxon Chemical Co., Ltd.) at room temperature.
(Manufactured by Mitsui Chemical Co., Ltd.) while being irradiated with an ultrasonic homogenizer, and then only tetrahydrofuran was removed using an evaporator, and then the ultrasonic homogenizer was irradiated again to obtain a black wet toner.

After the wet type developer (8) was prepared in the same manner as in Example 1, development evaluation and toner property evaluation were carried out, and the results are also shown in Table 2.

[0081]

[Example 9] 2-ethylhexyl methacrylate / methacrylic acid (copolymerization ratio = 95/5) 1.25 parts colorant (9) 1.50 parts zirconium naphthenate (Japan Chemical Industry Nikka Naphtex Zr, manufactured by Co., Ltd .... 25 g of a composition consisting of 2.50 parts of tetrahydrofuran and 30 g of tetrahydrofuran
After being dissolved in the solution, it was dispersed at room temperature using an ultrasonic homogenizer (Nippon Seiki Seisakusho Co., Ltd., US-300T), followed by Isopar G (Exxon Chemical Co., Ltd.) at room temperature.
(Manufactured by Mitsui Chemical Co., Ltd.) was added while irradiating an ultrasonic homogenizer, then only tetrahydrofuran was removed using an evaporator, and then the ultrasonic homogenizer was irradiated again to obtain a black wet toner.

After the wet type developer (9) was prepared in the same manner as in Example 1, development evaluation and toner property evaluation were carried out, and the results are also shown in Table 2.

[0083]

Example 10 2-Ethylhexyl methacrylate / methacrylic acid (copolymerization ratio = 95/5) 1.25 parts Colorant (10) 1.50 parts Zirconium naphthenate (Japan Chemical Industry Nikka Naphtex Zr, manufactured by Co., Ltd .... 25 g of a composition consisting of 2.50 parts of tetrahydrofuran and 30 g of tetrahydrofuran
After being dissolved in the solution, it was dispersed at room temperature using an ultrasonic homogenizer (Nippon Seiki Seisakusho Co., Ltd., US-300T), followed by Isopar G (Exxon Chemical Co., Ltd.) at room temperature.
(Manufactured by Mitsui Chemical Co., Ltd.) was added while irradiating an ultrasonic homogenizer, then only tetrahydrofuran was removed using an evaporator, and then the ultrasonic homogenizer was irradiated again to obtain a black wet toner.

Wet developer (10) was prepared in the same manner as in Example 1.
After preparing, the development evaluation and the toner characteristic evaluation were performed, and the results are also shown in Table 2.

[0085]

Example 11 2-Ethylhexyl Methacrylate / 2-Hydroxyethyl Methacrylate (Copolymerization ratio = 95/5) 1.25 parts Colorant (1) 1.50 parts Zirconium naphthenate ( Nikka Naftex Zr, manufactured by Nippon Kagaku Sangyo Co., Ltd .... 5.25 g of a composition consisting of 2.50 parts and 30 g of tetrahydrofuran
After being dissolved in the solution, it was dispersed at room temperature using an ultrasonic homogenizer (Nippon Seiki Seisakusho Co., Ltd., US-300T), followed by Isopar G (Exxon Chemical Co., Ltd.) at room temperature.
(Manufactured by Mitsui Chemical Co., Ltd.) while being irradiated with an ultrasonic homogenizer, and then only tetrahydrofuran was removed using an evaporator, and then the ultrasonic homogenizer was irradiated again to obtain a black wet toner.

Wet developer (11) was prepared in the same manner as in Example 1.
After preparing, the development evaluation and the toner characteristic evaluation were performed, and the results are also shown in Table 2.

[0087]

Example 12 n-lauryl methacrylate / 2-hydroxyethyl methacrylate (copolymerization ratio = 95/5) 1.25 parts Colorant (1) 1.50 parts Zirconium naphthenate ( Nikka Naftex Zr, manufactured by Nippon Kagaku Sangyo Co., Ltd .... 5.25 g of a composition consisting of 2.50 parts and 30 g of tetrahydrofuran
After being dissolved in the solution, it was dispersed at room temperature using an ultrasonic homogenizer (Nippon Seiki Seisakusho Co., Ltd., US-300T), followed by Isopar G (Exxon Chemical Co., Ltd.) at room temperature.
(Manufactured by Mitsui Chemical Co., Ltd.) while being irradiated with an ultrasonic homogenizer, and then only tetrahydrofuran was removed using an evaporator, and then the ultrasonic homogenizer was irradiated again to obtain a black wet toner.

Wet developer (12) was prepared in the same manner as in Example 1.
After preparing, the development evaluation and the toner characteristic evaluation were performed, and the results are also shown in Table 2.

[0089]

Comparative Example 1 2-Ethylhexyl Methacrylate / N, N-Dimethylacrylamide (Copolymerization ratio = 95/5) 1.25 parts Colorant (Carbon Black MA-100 manufactured by Mitsubishi Kasei Co., Ltd.)・ ・ ・ 1.50 parts zirconium naphthenate (Nikka Naftex Zr, manufactured by Nippon Kagaku Sangyo Co., Ltd.) ・ ・ ・ 2.50 parts of a composition of 5.25 g of tetrahydrofuran 30 g
After being dissolved in the solution, it was dispersed at room temperature using an ultrasonic homogenizer (Nippon Seiki Seisakusho Co., Ltd., US-300T), followed by Isopar G (Exxon Chemical Co., Ltd.) at room temperature.
(Manufactured by Mitsui Chemical Co., Ltd.) was added while irradiating an ultrasonic homogenizer, then only tetrahydrofuran was removed using an evaporator, and then the ultrasonic homogenizer was irradiated again to obtain a black wet toner.

After preparing the comparative developer (1) in the same manner as in Example 1, the development evaluation and the toner property evaluation were performed, and the results are also shown in Table 2.

[0091]

Comparative Example 2 2-Ethylhexyl Methacrylate / Methyl Methacrylate (Copolymerization ratio = 95/5) 1.25 parts Colorant (1) 1.50 parts Zirconium naphthenate (Japan Chemical Industry Nikka Naphtex Zr, manufactured by Co., Ltd .... 25 g of a composition consisting of 2.50 parts of tetrahydrofuran and 30 g of tetrahydrofuran
After being dissolved in the solution, it was dispersed at room temperature using an ultrasonic homogenizer (Nippon Seiki Seisakusho, Ltd., US-300T), and then room temperature Isopar G (manufactured by Exxon Chemical Co., Ltd.)
An ultrasonic homogenizer was added to 360 g while irradiating with an ultrasonic homogenizer, then only tetrahydrofuran was removed using an evaporator, and then the ultrasonic homogenizer was again irradiated to obtain a black wet toner.

Comparative developer (2) in the same manner as in Example 1.
After preparing, the development evaluation and the toner characteristic evaluation were performed, and the results are also shown in Table 2.

[0093]

[Comparative Example 3] 2-Ethylhexyl methacrylate / N, N-dimethylacrylamide (copolymerization ratio = 95/5) 1.25 parts Colorant (1) 1.50 parts Zirconium naphthenate (Nikka Naftex Zr, manufactured by Nippon Kagaku Sangyo Co., Ltd.) ... 25 g of a composition comprising 2.50 parts of tetrahydrofuran and 30 g of tetrahydrofuran
After being dissolved in the solution, it was dispersed at room temperature using an ultrasonic homogenizer (Nippon Seiki Seisakusho, Ltd., US-300T), and then room temperature Isopar G (manufactured by Exxon Chemical Co., Ltd.)
An ultrasonic homogenizer was added to 360 g while irradiating with an ultrasonic homogenizer, then only tetrahydrofuran was removed using an evaporator, and then the ultrasonic homogenizer was again irradiated to obtain a black wet toner.

After the comparative developer (3) was prepared in the same manner as in Example 1, development evaluation and toner property evaluation were carried out, and the results are also shown in Table 2.

[0095]

[Comparative Example 4] 2-Ethylhexyl methacrylate / 2-hydroxyethyl methacrylate (copolymerization ratio = 95/5) 1.25 parts Comparative colorant (11) 1.50 parts zirconium naphthenate (Nikka Naftex Zr, manufactured by Nippon Kagaku Sangyo Co., Ltd.) ... 25 g of a composition comprising 2.50 parts of tetrahydrofuran and 30 g of tetrahydrofuran
After being dissolved in the solution, it was dispersed at room temperature using an ultrasonic homogenizer (Nippon Seiki Seisakusho, Ltd., US-300T), and then room temperature Isopar G (manufactured by Exxon Chemical Co., Ltd.)
An ultrasonic homogenizer was added to 360 g while irradiating with an ultrasonic homogenizer, then only tetrahydrofuran was removed using an evaporator, and then the ultrasonic homogenizer was again irradiated to obtain a black wet toner.

After preparing the comparative developer (4) in the same manner as in Example 1, development evaluation and toner property evaluation were carried out, and the results are also shown in Table 2.

[0097]

[Comparative Example 5] 2-Ethylhexyl methacrylate / 2-hydroxyethyl methacrylate (copolymerization ratio = 95/5) 1.25 parts Comparative colorant (12) 1.50 parts zirconium naphthenate (Nikka Naftex Zr, manufactured by Nippon Kagaku Sangyo Co., Ltd.) ... 25 g of a composition comprising 2.50 parts of tetrahydrofuran and 30 g of tetrahydrofuran
After being dissolved in the solution, it was dispersed at room temperature using an ultrasonic homogenizer (Nippon Seiki Seisakusho, Ltd., US-300T), and then room temperature Isopar G (manufactured by Exxon Chemical Co., Ltd.)
An ultrasonic homogenizer was added to 360 g while irradiating with an ultrasonic homogenizer, then only tetrahydrofuran was removed using an evaporator, and then the ultrasonic homogenizer was again irradiated to obtain a black wet toner.

After preparing the comparative developer (5) in the same manner as in Example 1, the development evaluation and the toner property evaluation were performed, and the results are also shown in Table 2.

In Table 2 below, double circles are excellent, ◯ is good, Δ is a little bad, and x is a bad.

[0100]

[Table 2]

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masayuki Iijima 1-1-1, Ichigaya-Kagacho, Shinjuku-ku, Tokyo Dai Nippon Printing Co., Ltd. (56) Reference JP-A-3-274066 (JP, A) Special Features Kai 62-35370 (JP, A) JP-B 49-20995 (JP, B1) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03G 9/12-9/13

Claims (2)

(57) [Claims] 1. An electrically insulating dispersion medium in which copolymer resin particles comprising at least two kinds of monomer components containing a colorant are dispersed, and the copolymer resin is insoluble in the electrically insulating dispersion medium. In a wet developer consisting of a transparent core portion and an outer edge portion that surrounds the core portion and dissolves or swells in the electrically insulating dispersion medium, the colorant is a carbon black surface-modified with an aliphatic polyvalent amine. And a copolymer resin containing a hydroxy group or a carboxyl group. 2. The pH of the surface-modified carbon black
Is 5.0 or less, The wet type developer of Claim 1.