JP3077184B2 - Wet developer for electrostatic latent image development - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a wet developer for developing an electrostatic latent image for developing an electrostatic latent image in an electrophotographic process or the like.

[Summary of the Invention]

The present invention is to make the resin component contained in the wet developer a copolymer having a polyoxyethylene structure in the side chain,
It is intended to improve the interaction between the resin component, the charge donor, and the resin component, and the adsorption characteristics between the resin component and the colorant particles, thereby improving the charge characteristics of the colorant particles.

[Conventional technology]

In the field of image forming technology, a method of selectively irradiating light onto a uniformly charged photoconductor in accordance with an image signal and developing a formed electrostatic latent image is generally called an electrophotographic process. ing. This electrophotographic process is roughly classified into a dry developing method and a wet developing method.

The dry developing method has an advantage that it is excellent in handling property and preservation property of the developed toner because, in principle, it merely sprays and attaches a colorant powder to the electrostatic latent image. However, as seen in video printers and the like for printing electronic still photographs, in reality, in order to respond to the demand for high-quality images that have been increasing in recent years, it is necessary to give a step to wet development.

On the other hand, the wet development method uses a liquid developer in which a dye or pigment as a colorant is dispersed in an insulating medium. According to the wet development method, it is possible to obtain resolution and gradation comparable to silver halide photography, and particularly when a pigment is used as a colorant, the formed image has excellent weather resistance, and Development is under way.

Conventionally, as a developer used in a wet development method, a wet developer (hereinafter referred to as a liquid) in which an insulating medium is a liquid substance at normal temperature represented by, for example, a saturated hydrocarbon-based Isopar G (manufactured by Esso Corporation). Is generally known.

Furthermore, a wet developer that disperses colorant particles and the like in an electrically insulating organic substance that is solid at room temperature and liquefies by heating at a normal temperature to solve problems such as difficult handling of liquid toner, complicated maintenance, and poor storage stability. (Hereinafter referred to as solid toner) has already been proposed by the present applicant in Japanese Patent Application No. 63-156846.

This solid toner has advantages such as easy handling and little change in composition due to being solid when stored, and wet development similar to ordinary liquid developers by being melted by an appropriate heating means when used. Is possible.

[Problems to be solved by the invention]

By the way, in the wet developer used in the above-mentioned wet developing method, a resin component is added to both the liquid toner and the solid toner to adsorb the colorant particles and take in the charge donor. As a polymer conventionally used as such a resin component, a copolymer of styrene, dodecyl acrylate, or the like is mainly used for the purpose of enhancing solubility in a nonpolar solvent.

However, the above-mentioned copolymer has a weak interaction with a charge donor indispensable for a wet developer due to a small coordination field for taking in metal ions, and has no polar functional group in a side chain. There is a problem that the adsorptivity to the colorant particles and the fixability to the photoreceptor film are not sufficient.
Therefore, satisfactory resolution, gradation, and fixability have not been obtained. Particularly, in the case of a solid toner, it is necessary to heat at the time of development, so that the adsorbability of the resin component to the colorant particles tends to be insufficient, and the above-mentioned inconvenience is noticeable.

Further, in the above-mentioned conventional copolymer, it is necessary to add a resin component of about 2 to 5 times the amount of the colorant particles,
Problems such as a change in composition due to repetition of development and sticking of the resin to the developing device are caused.

A study on the resin component of a wet developer can be found in, for example, JP-A-61-156262, etc., which mainly focuses on fixing, and the charge donor and the colorant as described above. No one considers interaction with particles.

In view of the above, the present invention has been proposed in view of the above-described conventional circumstances, and has increased the interaction of a resin component used in a wet developer with a charge donor, thereby improving the adsorption characteristics to colorant particles. Accordingly, an object of the present invention is to provide a wet developer for developing an electrostatic latent image, which is excellent in charge characteristics of colorant particles and excellent in resolution, gradation and fixability.

[Means for solving the problem]

The present inventors have studied various copolymers with an emphasis on interaction with a charge donor or a colorant particle, and found that it is effective to introduce a polyoxyethylene structure into a side chain. I came to.

The present invention has been completed based on such findings, and comprises a dispersion medium, colorant particles, a resin component and a charge donor, wherein the resin component has a polyoxyethylene structure in a side chain. Characterized in that it is a copolymer having

The polyoxyethylene structure has a repeating unit of —O—CH ₂ CH ₂ —, and a coordination field is formed by its oxygen atom. In this case, it is necessary that the polyoxyethylene structure is introduced into the side chain of the copolymer, and even if the polyoxyethylene structure is introduced into the main chain, the effect of forming a coordination field cannot be expected.

Therefore, it is necessary to use, as the resin component, a copolymer having a polyoxyethylene structure introduced into a side chain. In the present invention, in particular, compatibility with a dispersion medium and formation of a coordination field due to a carboxyl group, etc. In consideration of the above, an acrylate copolymer represented by the following formula (I) is used.

However, in the copolymer represented by the formula (I),
R ¹ , R ² and R ³ each represent hydrogen or a methyl group, and j is 1
And m represents an integer of 10 to 30. As for j and m, two or more kinds of j and m may be combined within the above range.

Further, x, y, and z indicate the constitutional ratio of each monomer, x is 0 to 0.8, y is 0.2 to 0.9999, and z is 0.0001 to 0.05.
Preferably, x is 0.2 to 0.8, z is 0.001 to 0.0
More preferably, it is set to 5. When the value of x is out of the above range, the coordination field due to the ester bond portion is reduced and it becomes difficult to take in the charge donor, and when the value of y is out of the above range, problems such as solubility in the dispersion medium occur. Furthermore, z
Is less than 0.0001, the effect of introducing a polyoxyethylene structure is insufficient, and conversely, if it exceeds 0.05, the solubility decreases.

On the other hand, the number n of repeating unit units in the polyoxyethylene structure is preferably 2 to 23. If n is too large, it will be difficult to dissolve in a nonpolar solvent. If it is too small, the solubility will be improved, but the function as a functional group will be reduced.

The molecular weight of the above-mentioned copolymer is 3000 to 3,000 in number average molecular weight Mn.
It is preferably 100,000, more preferably 5,000 to 50,000.

The wet developer of the present invention contains a dispersing medium, colorant particles, a charge donor, a charge enhancer, and the like in addition to the resin components described above. First, if the dispersing medium is an electrically insulating organic substance, it is liquid at room temperature. Or solid. In short, it may be liquefied during development.

As the liquid electrically insulating organic substance, for example, aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, polysiloxanes, etc. can be used. From the viewpoint, isoparaffinic petroleum solvents are preferred. Examples of the isoparaffin-based petroleum solvent include Isopar G, Isopar H, Isopar L, Isopar K (all manufactured by Esso), Shellsol 71 (manufactured by Shell Petroleum), and the like.

In the case of a solid electrically insulating organic substance, the melting point is set to 30 ° C. or higher, more preferably 40 ° C. or higher, in consideration of a normal use environment and handleability. Although the upper limit of the melting point is not particularly limited, it is practically about 100 ° C, more preferably 80 ° C or less. The reason for this is that extra energy is consumed for heating even if the melting point is too high, and that the material must not exceed the heat resistance temperature of the material generally used as a base when used while being held on the base. It depends.

Materials that meet these requirements include paraffins,
Waxes, and mixtures thereof. First, as paraffins, there are various normal paraffins having 19 to 60 carbon atoms ranging from nonadecane to hexacontan. Also, as waxes, carnauba wax, vegetable waxes such as cotton wax,
Animal wax such as beeswax, ozokerite, and petroleum wax such as paraffin wax, microcrystalline wax, petrolatum and the like. These materials are dielectrics having a dielectric constant ε of about 1.9 to 2.3.

Furthermore, a side chain such as polyethylene, polyacrylamide, polyacrylate homopolymer or copolymer such as poly n-stearyl acrylate or poly n-stearyl methacrylate (for example, copoly n-stearyl acrylate ethyl methacrylate) has a long alkyl group in the side chain. Although crystalline polymers can be used, the above-mentioned paraffins and waxes are preferable in consideration of the viscosity during heating and the like.

Further, as the colorant particles dispersed in the above-described dispersion medium, conventionally known inorganic pigments, organic pigments, dyes, and mixtures thereof can be used.

For example, examples of the inorganic pigment include a chromium pigment, a cadmium pigment, an iron pigment, a cobalt pigment, ultramarine, navy blue, and the like. Organic pigments and dyes include Hiza Yellow (CI11680) and Benzidine Yellow G (CI2109
0), benzidine orange (CI21110), fast red (CI37085), brilliant carmine 3B (CI160
15-Lake), Phthalocyanine Blue (CI74160), Victoria Blue (CI42595-Lake), Spirit Black (CI50415), Oil Blue (CI74350), Alkaline Blue (CI42770A), Fast Scarlet (CI12315), Rhodamine 6B (CI45160), Rhodamine Lake (CI45160-Lake), Fast Sky Blue (CI74200-Lake), Nigrosine (CI50415), carbon black and the like. These can be used alone or as a mixture of two or more kinds, and those having a desired color may be selected and used.

Further, in addition to the above-described resin component having a polyoxyethylene structure in the side chain, a known resin material can be appropriately selected and used in combination. Examples of such resin materials include butadiene rubber, styrene-butadiene rubber, cyclized rubber, rubbers such as natural rubber, styrene resins, vinyl toluene resins, acrylic resins, polycarbonate resins, polyvinyl acetate resins, and the like. Examples include synthetic resins, rosin resins, hydrogenated rosin resins, alkyd resins including modified alkyds such as linseed oil modified alkyd resins, and natural resins such as polyterpenes. In addition, modified phenol resins such as phenol resins and phenol formalin resins, pentaerythritol phthalate, coumarone-indene resins, ester gum resins, vegetable oil polyamide resins, etc. are also useful, and polyvinyl chloride, chlorinated Halogenated hydrocarbon polymers such as polypropylene, synthetic rubbers such as vinyl toluene-butadiene, butadiene-isoprene, and long-chain alkyl groups such as 2-ethylhexyl methacrylate, lauryl methacrylate, stearyl methacrylate, lauryl acrylate, and actyl acrylate Of acrylic monomers having the above or copolymers thereof with other polymerizable monomers (eg, styrene-lauryl methacrylate copolymer, acrylic acid-lauryl methacrylate copolymer), polyethylene Polyolefins, polyterpenes, and the like can also be used of.

Usually, a charge donor is added to a wet developer. Additives that can be used include, for example, metal salts of fatty acids such as naphthenic acid, octenoic acid, oleic acid, stearic acid, isostearic acid or lauric acid, metal salts of sulfosuccinates, metal salts of oil-soluble sulfonic acids, phosphate esters Metal salts, metal salts such as abietic acid, aromatic carboxylic acid metal salts, aromatic sulfonic acid metal salts and the like.

Further, in order to improve the charge of the colorant particles, SI
O ₂ , Al ₂ O ₃ , TiO ₂ , ZnO, Ga ₂ O ₃ , In ₂ O ₃ , GeO ₂ , SnO ₂ , Pb
Metal oxide particles such as O ₂ and MgO or a mixture thereof may be added as a charge enhancer.

Regarding the compounding ratio of each of the above-mentioned components, first, the amount of the colorant particles is preferably 0.01 to 100 g, more preferably 0.1 to 10 g, per 1 of the dispersion medium. In order to perform particularly efficient development and suppress the amount of waste toner, the concentration with respect to the dispersion medium [comparison between the dispersion medium and the colorant (dilution ratio)] is 2 to 10% by weight.
It is preferable that

Note that the concentration range of the coloring agent is a concentration in the developing step to the last, and may be concentrated to a higher concentration during storage, for example.

The resin component is added in the range of about the same amount or less as the colorant particles.
It is preferably from 0.1 to 100 g, more preferably from 0.1 to 1 g.
It is 0g.

The charge donor is also usually 0.001 to 10 per 1
g, preferably in the range of 0.01 to 1 g. Further, the charge enhancer is added in a weight ratio of not more than twice, preferably not more than the weight of the colorant particles.

In the preparation of the wet developer of the present invention, a kneading agent such as oleic acid is added, and the kneading agent is adsorbed on the coloring agent particles so as to improve the adsorbability of the resin component to the coloring agent particles. Is also good.

[Action]

The copolymer having a polyoxyethylene structure itself is excellent not only in the adsorptivity to the colorant particles but also in the interaction with the charge donor.

This means that, as shown in FIG. 1, the polyoxyethylene chain present in the side chain of the copolymer behaves as if it were a crown ether, and the coordination field formed by the polyoxyethylene chain provides a charge donating. This is because the metal ions of the agent are surrounded.

Further, in the copolymer of the present invention, a coordination field is also formed by the carboxyl oxygen in the ester bond portion derived from the acrylic monomer, and this portion also surrounds the metal ion as shown in FIG.

In the wet developer of the present invention, the interaction with the charge donor is ensured by these coordination fields of the resin component, and the charge characteristics of the colorant particles are improved.

〔Example〕

Hereinafter, the present invention will be described based on specific experimental results.

Synthetic Example 1 of Resin Acrylic monomer was weighed and added to a monomer weight of 0.
5% of the initiator AIBN [α, α′-azobis (isobutyronitrile)] was added. After adding a 5-fold amount of a solvent (dimethylformamide), the mixture was degassed and sealed using a vacuum line. After reaction at 70 ° C. for 18 hours, the tube was opened, a reaction terminator (hydroquinone) was added, and the mixture was purified three times from a mixed solvent of n-hexane and ethanol for purification. After completely removing the solvent, an equivalent amount of toluene was added to the synthesized resin,
After dispersing, it was stored.

The resins shown in Table 1 were synthesized according to the above synthesis method. These resins are synthesized from methyl acrylate, stearyl acrylate, and methoxytetraethylene glycol methacrylate (or methoxydiethylene glycol methacrylate). In the above formula (I), j = 1 and m = 18. The methyl acrylate is copolymerized for the purpose of improving the flexibility of the resin, and the stearyl acrylate is copolymerized for the purpose of improving the solubility in a paraffinic solvent.

In Table 1, the resin AS1-1 does not have a polyoxyethylene structure, and is a comparative example. Also. A copolymer of styrene and dodecyl acrylate (manufactured by Mitsubishi Rayon Co., Ltd.) was designated as resin FR101 for comparison.

Example 1 A developer was prepared in the following ratio.

Kneading agent (oleic acid) ... 0.60 g Pigment (colorant particles) ... 0.50 g Zirconium octylate ... 1 drop Calcium octylate ... 1 drop Resin (AD2-2) ... 0.25 g Isopar H: 50 ml These were put in a container together with glass beads, and sufficiently dispersed in a pay-in shaker.

For comparison, a similar developer was prepared using Resin AS1-1 and Resin FR101.

Comparison of the total charge, excess ionic charge and pigment charge of each of the prepared developers was made by electrophoresis. At this time, the stock toner solution was diluted 10 times with Isopar H. Total charge, excess ionic charge is the amount of charge per ml in the undiluted developer,
The pigment charge was calculated as the charge amount of 1 g of the pigment. Second result
It is shown in the table.

As is clear from Table 2, the pigment charge can be reduced to 25% of that of the developer using the conventional FR101 by copolymerizing only 1% of methoxytetraethylene glycol methacrylate.
It has improved about twice.

Example 2 A developer was prepared in the same manner as in Example 1 except that the resin was AD2-1, and the charge was measured.

As a result, the total charge was 244.36 × 10 ⁻⁶ C / ml, the excess ionic charge was 178.39 × 10 ⁻⁶ C / ml, and the pigment charge was 69.08 to 10 ⁻⁴ C / g. Also in this AD2-1, the pigment charge is the same as that of the conventional FR101.
It was improved to about 250 times.

Example 3 A developer was prepared in the same manner as in Example 1 except that the resin was AD1-1, and the charge was measured.

As a result, the total charge was 60.76 × 10 ⁻⁶ C / ml, the excess ionic charge was 45.14 × 10 ⁻⁶ C / ml, and the pigment charge was 16.52 × 10 ⁻⁴ C / g. Also in this AD1-2, the pigment charge is the same as that of the conventional FR101.
About 59 times higher.

Example 4 A developer was prepared in the same manner as in Example 1 except that the resin was AD1-2, and the charge was measured.

As a result, the total charge was 56.86 × 10 ⁻⁶ C / ml, the excess ionic charge was 39.06 × 10 ⁻⁶ C / ml, and the pigment charge was 18.82 × 10 ⁻⁴ C / g. Also in this AD1-1, the pigment charge is the same as that of the conventional FR101.
It has been improved to about 59 times compared to.

Example 5 The kneading agent was an isoparaffin-based solvent (IP2, manufactured by Idemitsu Petrochemical Co., Ltd.).
835) A developer was prepared using 0.50 g of resin AD2-2, AS1-1, and FR101, and the charge was measured. The results are shown in Table 3.

As a result, the pigment charge was improved about 70 times as compared with the conventional FR101.

Example 6 A developer was prepared using resin AD2-1 in the same manner as in Example 5, and the charge was measured.

As a result, the total charge was 241.75 × 10 ⁻⁶ C / ml, the excess ionic charge was 176.22 × 10 ⁻⁶ C / ml, and the pigment charge was 68.19 × 10 ⁻⁴ C / g. The pigment charge was improved about 40 times compared to the conventional FR101.

Example 7 A developer was prepared using Resin AD1-2 in the same manner as in Example 5, and the charge was measured.

As a result, the total charge was 15.19 × 10 ⁻⁶ C / ml, the excess ionic charge was 6.94 × 10 ⁻⁶ C / ml, and the pigment charge was 9.45 × 10 ⁻⁴ C / g. The pigment charge was improved about 5 times as compared with the conventional FR101.

Example 8 A developer was prepared using Resin AD1-1 in the same manner as in Example 5, and the charge was measured.

As a result, the total charge was 34.29 × 10 ⁻⁶ C / ml, the excess ionic charge was 15.63 × 10 ⁻⁶ C / ml, and the pigment charge was 20.89 × 10 ⁻⁴ C / g. The pigment charge was improved about 10 times compared to the conventional FR101.

Example 9 An electric charge was measured when the solvent was paraffin and the composition was exactly the same as in Example 1. However, since paraffin is a solid at room temperature, the charge was measured in a state of being dissolved at 50 ° C. Table 4 shows the results.

Even when paraffin is used as the dispersion medium, FR10
The pigment surface charge is improved 200 times or more as compared with the case where the composition No. 1 is prepared. Also, by including the polyoxyethylene structure as a resin composition of only 1%, the charge is improved by 10 times or more. However, the surface charge is slightly lower than the value when the isoper at room temperature is used as the dispersion medium. This is considered to be due to the fact that the resin is easily separated from the pigment surface due to thermal vibration.

Example 10 The same dispersion medium as in Example 2 was used as paraffin.

As a result, the total charge was 220.54 × 10 ⁻⁶ C / ml, the excess ionic charge was 159.00 × 10 ⁻⁶ C / ml, and the pigment charge was 67.69 × 10 ⁻⁴ C / g. The pigment surface charge was more than 200 times higher than the conventional FR101.

Example 11 The same dispersion medium as in Example 3 was used as paraffin.

As a result, the total charge was 53.80 × 10 ⁻⁶ C / ml, the excess ionic charge was 40.32 × 10 ⁻⁶ C / ml, and the pigment charge was 14.55 × 10 ⁻⁴ C / g. The pigment surface charge was improved more than 40 times compared with the conventional FR101. This resin has a side chain polyoxyethylene structure of AD
It is shorter than 2-1 and AD2-2. Therefore, it is understood that the longer the polyoxyethylene structure is, the easier it is to take in electric charges.

Example 12 The same composition as in Example 4 was used except that the dispersion medium was paraffin.

As a result, the total charge was 50.04 × 10 ⁻⁶ C / ml, the excess ionic charge was 40.88 × 10 ⁻⁶ C / ml, and the pigment charge was 9.90 × 10 ⁻⁴ C / g. The pigment surface charge was improved more than 30 times compared with the conventional FR101.

Example 13 The same composition as in Example 5 was used except that the dispersion medium was paraffin.

As a result, the total charge was 199.50 × 10 ⁻⁶ C / ml, the excess ionic charge was 88.50 × 10 ⁻⁶ C / ml, and the pigment charge was 119.8 × 10 ⁻⁴ C / g.

The difference from Example 9 was only the kneading agent, and the kneading agent in this case was IP2835.

Example 14 A dispersion medium having the same composition as in Example 6 was used as paraffin.

As a result, the total charge was 200.75 × 10 ⁻⁶ C / ml, the excess ionic charge was 153.30 × 10 ⁻⁶ C / ml, and the pigment charge was 52.19 × 10 ⁻⁴ C / g.

Similarly, AD2-1 was used, and IP2835 was used as a kneading agent.

Example 15 A dispersion medium having the same composition as that of Example 7 was paraffin.

As a result, the total charge was 13.44 × 10 ⁻⁶ C / ml, the excess ionic charge was 9.01 × 10 ⁻⁶ C / ml, and the pigment charge was 4.87 × 10 ⁻⁴ C / g.

In this case, the surface charge does not increase much. As a kneading agent, it can be seen that oleic acid of Example 11 is better than IP2835 used in this example.

Example 16 A dispersion medium having the same composition as in Example 8 was used as paraffin.

As a result, the total charge was 20.11 × 10 ⁻⁶ C / ml, the excess ionic charge was 8.85 × 10 ⁻⁶ C / ml, and the pigment charge was 12.38 × 10 ⁻⁴ C / g.

Also in this case, the improvement of the surface charge is not so large, but FR
It turns out that it is considerably improved compared with 101.

Development Example Development was performed using a developer prepared for charge measurement. However, the developing solutions of Examples 1 to 8 are at room temperature, while the developing solutions using paraffin as a dispersion medium prepared in Examples 9 to 16 are
Development was performed in the region of 45-75 ° C.

Developing Example 1 Table 5 shows the developing characteristics when Isopar H was used as the dispersion medium.

The resolution when the composition is FR101 is about 33 lines / mm. Therefore, in this case, the resolution is very good. When the composition is FR101, the fixability is low enough to peel off the pigment when rubbed a little, but in this case, the fixability is considerably improved. Further, the developing density in this case was about 3 times or more in terms of the absorbance ratio as compared with the developing density in the case of using FR101.

Developing Example 2 Table 6 shows the developing characteristics at 45 ° C. when paraffin was used as the dispersion medium.

Even in the case where paraffin is used as the dispersion medium, the same characteristics as in the case of development at room temperature using Isopar can be obtained.

Developing Example 3 Table 7 shows the developing characteristics at 55 ° C. when paraffin was used as the dispersion medium.

Developing Example 4 Table 8 shows the developing characteristics at 65 ° C. when paraffin was used as the dispersion medium.

Developing Example 5 Table 9 shows the developing characteristics at 75 ° C. when paraffin was used as the dispersion medium.

At high temperatures, especially at 65 ° C. or higher, little toner fixation is observed in a developer containing FR101. This is FR10
It is considered that in the case of 1, the resin and the toner are dissociated by thermal vibration at a high temperature. However, in this case, although the development density is slightly lowered, development can be sufficiently performed even at 75 ° C., and the resolution is sufficient.

Resin Synthetic Part 2 In this synthesis example, a resin having a long polyoxyethylene chain was synthesized. The synthesis method was the same as in Synthesis Example 1. Of synthetic resin
x, y, z, n, weight average molecular weight Mw, number average molecular weight Mn
It is shown in the table.

Example 17 Magenta lake pigment: 0.8 g Resin (YD3-1): 0.5 g Isoparaffin-based solvent: 0.6 g The above composition was kneaded by a Hoover-Murler method.

Next, Isopar H50m, an isoparaffin solvent
l and a few drops of the charge donor were added, and the mixture was stirred for several hours on a paint shaker to be sufficiently dispersed.

When the magenta toner prepared in this way was developed at high temperature, high resolution of 50 lines / mm or more, high dispersibility in a non-polar solvent, and excellent gradation, transparency, and fixability were obtained. Was achieved.

Example 18 Paraffin instead of Isopar H (melting point 42-44 ° C)
Magenta toner was prepared in the same manner as in Example 17 except that

When development was performed at a high temperature using this magenta toner, the same results as in Example 17 were obtained.

Example 19 A resin (YD4-1) was used in place of the resin (YD3-1),
Otherwise, a magenta toner was prepared in the same manner as in Example 17.

When developed with this magenta toner at high temperature, high resolution of more than 50 lines / mm, high dispersibility in a non-polar solvent, and excellent gradation, transparency, and fixability were also achieved. .

Example 20 Instead of Isopar H, paraffin (melting point 42-44 ° C)
Magenta toner was prepared in the same manner as in Example 19 except that

When development was performed at a high temperature using this magenta toner, the same results as in Example 19 were obtained.

〔The invention's effect〕

As is clear from the above description, in the present invention, since the copolymer having a polyoxyethylene structure in the side chain is used as the resin component, the interaction with the charge donor and the adsorptivity to the colorant particles are significantly increased. Can be improved.

Therefore, it is possible to perform wet development with excellent resolution, gradation, and fixability.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a state of taking in metal ions by a polyoxyethylene structure. FIG. 2 is a schematic diagram showing a state of capturing metal ions in an ester bond.

────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Haruo Watanabe 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (56) References JP-A-50-125743 (JP, A) JP-A Sho 60-121458 (JP, A) JP-A-60-166477 (JP, A) JP-A-60-225858 (JP, A) JP-A-61-278868 (JP, A) JP-A-62-66270 (JP, A) A) JP-A-2-259660 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 9/13

Claims (1)

(57) [Claims] 1. A copolymer comprising a dispersion medium, colorant particles, a resin component, and a charge donor, wherein the resin component has a polyoxyethylene structure in a side chain and is represented by the following chemical formula (I): A wet developer for developing an electrostatic latent image, wherein (Wherein, R ¹ , R ² , and R ³ each represent hydrogen or a methyl group, j represents an integer of 1 to 3, m represents an integer of 10 to 30, and n represents an integer of 2 to 23. Further, x, y, and z indicate the constituent ratio of each monomer, x is 0 to 0.8, y is 0.2 to 0.9999, and z is 0.
0001-0.05. )