JPH07128899A - Electrostatic charge image developing toner - Google Patents

Abstract

PURPOSE:To attain sufficient releasing effect with a small quantity of a releas ing agent fixed, to increase flowability and transfer property and to obtain a bright image by fixing releasing agent fine particles containing a fluorine based 'Nonion(R)' surfactant on the surface of thermoplastic resin particles containing a colorant. CONSTITUTION:This toner is made by fixing the releasing agent particles containing the fluorine based 'Nonion(R)' surfactant on the surface of the thermoplastic resin particles containing the colorant. The producing method is composed of a process for producing the thermoplastic resin particles containing the colorant and a process for sticking and fixing the releasing agent particles containing the fluorine based surfactant. In this case, the particles made by coloring the resin particles obtained by dispersion polymerization is preferable as the colored resin fine particles because the particles having narrow particle diameter distribution and small particle diameter are easily obtained. Where, the dispersion polymerization is a method for polymerizing a monomer in a solvent, in which the monomers is dissolved but the polymer is not dissolved, in the presence of a dispersion stabilizer dissolved in the solvent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic charge image developing toner used in electrophotography, electrostatic printing, electrostatic recording and the like.

[0002]

2. Description of the Related Art As means for developing an electrostatic latent image formed on an electrophotographic photoreceptor or electrostatic recording body, a method using a liquid developer (wet developing method) and a method using a binder resin dye,
A method in which a colorant such as a pigment and, if necessary, a release agent, a charge control agent, or the like is dispersed, or a one-component or two-component dry developer in which the toner is mixed with a solid carrier (dry development Law) and are generally adopted. Although each of these methods has advantages and disadvantages, at present, the dry developing method is widely used.

In order to obtain high image quality and high durability, the toner should have a small particle size, a narrow particle size distribution, a smooth surface shape, and a charge control agent uniformly dispersed. Is required. That is, the particle size affects the resolution, sharpness, halftone reproducibility, etc., and a wide particle size distribution causes selective development of a specific particle size.
Difficulty in durability. If the surface shape is not smooth, due to the stress during stirring in the developing area, partial pulverization occurs on the surface and ultrafine powder is generated, which in the two-component type developer fuses to the carrier and deteriorates charging. In the one-component developer, the toner is fused to the toner thin film member, which causes white stripes. In addition, the uneven distribution of the charge control agent in the toner causes scumming.

A conventional general method for producing a toner, that is, a method in which a resin, a dye / pigment, a release agent and a charge control agent are melt-kneaded and then pulverized and classified by a mechanical or air collision pulverizer. When a toner having a small particle size and a narrow particle size distribution is produced, the production capacity and the yield are significantly reduced and the cost is increased. The influence of the non-uniformity of the dispersion of the property-imparting agent such as the charge control agent and the release agent added therein becomes remarkable.

On the other hand, these dry toners are fixed on the electrostatic latent image or transferred to a support such as paper and then fixed to form a visible image. There are various methods for fixing the toner, but the heat roller fixing method is preferably generally used from the viewpoints of thermal efficiency and fixing speed. However, the hot roller fixing method causes problems such as hot offset and the generation of nail marks. Hot offset is a phenomenon in which molten toner is fused to a heat roller and re-transferred to a support such as transfer paper, and a nail mark is provided to separate the support such as paper from the fixing roller. This is a phenomenon in which the toner on the melted image adheres to the separation claw and a defective portion on the white line is generated in the image.

In order to prevent this, a method of applying a releasing liquid such as silicone oil to the fixing roller is used. Although this method is effective, it requires mounting to apply the releasing liquid to the fixing roller, which complicates the apparatus,
Also, expensive materials such as silicone oil are required,
There is a problem in that the cost is increased, and when a releasable liquid such as silicone oil is heated, it evaporates to contaminate the surroundings and cause an unpleasant odor.

As a method of preventing hot offset of the toner without using silicone oil, a method of mixing a releasing agent such as low molecular weight polyolefin wax into the toner resin has been proposed (JP-A-49-65231).
Issue). The release agent existing near the toner surface acts as an effective release agent, but it is necessary to knead 5 to 10% by weight of the release agent into the toner in order to obtain a sufficient offset preventing effect. is there. These release agents have poor compatibility with the binder resin of the toner, and it is difficult to uniformly knead a large amount of the release agent, and the release agent added in a large amount lowers the blocking resistance, However, problems such as filming on carriers and the like, and spent are generated. In order to solve these problems, JP-A-63-41861, JP-A-63-244053, and JP-A-63-300245
In each of the publications, a method of providing a layer containing a release agent on the outer layer of the toner is proposed.

A dispersion polymerization method is effective as a method for producing a toner having a small particle size and a uniform particle size distribution. The dispersion polymerization method is a method of polymerizing in a solvent in which a monomer is dissolved but a polymer produced therefrom is not dissolved in the presence of a dispersion stabilizer soluble in the solvent, and a resin having a small particle size and a narrow particle size distribution. Although it is an advantageous method for producing particles, it is difficult to include a property-imparting agent such as a release agent in the particles, so the method of fixing the release agent to the resin particle surface yields an oil-free toner. It is an effective method for

However, in the method using a fine powder of a mixture of a polyolefin as a release agent and another thermoplastic resin as disclosed in JP-A-63-41861 and JP-A-63-244053. Not only is it extremely difficult to obtain a fine powder, but because of the adhesiveness of the polyolefin exposed on the toner surface, the fluidity is reduced and the transferability from the photoreceptor to the transfer paper or the like is reduced. Therefore, it becomes difficult to obtain a clear image with high density. Also, JP-A-63-3002
According to the method using a wax emulsion disclosed in Japanese Patent Laid-Open No. 45, it is easy to obtain fine wax particles, but the effect of the emulsifier used in the emulsion is added, and the fluidity
The decrease in transferability is even more remarkable.

Further, Japanese Patent Application Laid-Open No. 1-257853 discloses a method of fixing resin fine particles containing polypropylene prepared by soap-free emulsion polymerization on the surface of a suspension-polymerized toner. In this method, soap-free toner is used. Even if polypropylene is included in the emulsion polymerization, it is difficult to make resin fine particles, and even if polypropylene is contained, the amount is very small, and in these fine particles, the ratio of the non-releasing resin to polypropylene that acts as a mold releasing agent. There was a problem that the releasing agent was not likely to be exposed on the surface, the releasing agent could not be eluted even by heating, and the releasing effect was not exhibited. Further, JP-A-4-147268 discloses a toner in which a fluorine-based surfactant is added to a binder resin of the toner. The toner has an effect of improving the fixing property of the toner, but the offset -There is no effect to reduce the phenomenon of nail marks.

[0011]

As described above, according to the conventional technique, the toner having the release agent particles adhered to the surface has a lowered fluidity / transferability, and the fluidity / transferability and releasability are reduced. It was not possible to achieve both at the same time, and it was difficult to obtain a clear image with high density.

Therefore, the object of the present invention is to solve the problems of the prior art and to obtain a clear image with high density and excellent fluidity.
An object of the present invention is to provide an electrostatic charge image developing toner having excellent fluidity, releasability, transferability and durability.

[0013]

According to the present invention, release agent fine particles containing a fluorine-containing nonionic surfactant are fixed to the surface of thermoplastic resin particles containing a colorant. A toner for developing an electrostatic charge image is provided.

Generally, the releasing agent present on the toner surface is plasticized by heat and pressure applied in the copying process to generate tackiness,
Adhesion between the toners increases, and the fluidity and transferability of the toner deteriorate. Therefore, in order to prevent deterioration of fluidity and transferability, it is desirable to prevent the occurrence of offset and the like by fixing a small amount of the release agent, but the performance of known release agents is not sufficient. As the function of the release agent, the release agent melted by heating during fixing uniformly coats the toner surface with a thin layer, prevents contact between the melted toner binder resin and the fixing roller, and prevents the occurrence of offset or the like. It is conceivable that it is difficult to form a uniform thin layer on the toner surface by melting with a known release agent, and it is necessary to fix a relatively large amount of release agent in order to prevent the occurrence of offset and the like. , Which has been a cause of deterioration in fluidity and transferability.

However, in the toner of the present invention, since the release agent fine particles containing the fluorine-based nonionic surfactant are fixed to the toner surface uniformly, the melted release agent uniformly covers the toner surface. This makes it easy to prevent the occurrence of offset and the like by fixing a small amount of the release agent. Moreover, the fluorine-based nonionic surfactant contained in the release agent is considered to be present on the surface of the release agent fine particles due to its oil repellency, which effectively acts to prevent the adhesion of the toners to each other, and It also has the effect of improving fluidity and transferability. Therefore, the toner of the present invention has excellent fluidity and transferability, and excellent releasability.

The production of the toner of the present invention comprises a step of producing thermoplastic resin particles containing a colorant and a step of adhering and fixing release agent fine particles containing a fluorosurfactant. Examples of the colored resin particles used in the present invention include particles obtained by kneading and pulverizing a colorant and a resin, or particles obtained by suspension polymerization of a polymerizable monomer containing a colorant, and the like. The particles obtained by coloring the resin particles obtained by the dispersion polymerization method are preferable from the viewpoint that particles having a narrow particle size distribution can be easily obtained. Dispersion polymerization is a method of polymerizing a monomer in a solvent in which a monomer dissolves but a polymer produced therefrom does not dissolve in the presence of a dispersion stabilizer dissolved in the solvent. As the monomer, styrenes, methacrylic acid esters, and acrylic acid esters known in the electrophotographic field are preferably used. Further, in order to control the molecular weight distribution, the polymerization may be carried out in the coexistence of a crosslinking agent and a chain transfer agent.

The resin particles may be colored resin particles by fixing a coloring agent such as a pigment on the surface, but it is preferable to color the resin particles with a dye from the viewpoint of fixing property. Coloring with a dye is performed by immersing the resin particles in a dye solution that does not dissolve the resin particles and heating the resin particles if necessary. SP of dye at this time
The value and the SP value of the resin are preferably close.

The step of fixing the releasing agent fine particles containing the fluorine-based nonionic surfactant to the toner surface is carried out by uniformly adhering the releasing agent fine particles to the toner surface and then heating. The release agent as referred to herein means a substance that melts during hot roller fixing and has an effect of preventing adhesion between the roller and the toner on the material to be fixed, and has the effect of preventing the offset phenomenon. Means any substance that has.

Specific examples of these substances include low molecular weight polyolefins having a number average molecular weight of 1,000 to 20,000 such as polypropylene, polyethylene, polypropylene oxide and polyethylene oxide; candelilla, carnauba, rice, wood wax, jojoba, etc. Natural waxes of minerals; mineral natural waxes such as montan, ceresin, ozokerite; petroleum waxes such as paraffin, microcrystalline, petrylactam; and their modified waxes; palmitic acid, stearic acid, behenic acid, etc. Solid higher fatty acids; higher fatty acids such as calcium stearate, aluminum stearate, calcium palmitate, zinc palmitate, alkali metal salts, zinc salts, aluminum salts; higher fats such as octadecyl stearate and glycerin monostearate. Acid esters; amides such as lauric acid amide, stearic acid amide, N, N′-ethylenebisoleic acid amide, N, N′-ethylenebisstearic acid amide; ketones such as diheptadecyl ketone and diundecyl ketone Is mentioned.

The fluorine-based nonionic surfactant used in the present invention is preferably oil-soluble, and for example, perfluoroalkylethylene oxide adduct, perfluoroalkylalkoxylate, perfluoroalkyl ester, perfluoroalkyl group-containing oligomer. Etc. These fluorine-based surfactants are used in an amount of 0.1 to 10% by weight, preferably 0.5 to 5% by weight, based on the release agent. If it is less than 0.1% by weight, the effect of addition does not appear,
If it exceeds 10% by weight, fluidity and transferability are rather deteriorated.

The release agent fine particles containing a fluorine-based nonionic surfactant are obtained by melt-mixing the surfactant with the release agent and then forming fine particles. It is preferable that the release agent fine particles have a particle diameter of 1/10 or less of the toner particle diameter from the viewpoint of uniformly adhering to the toner surface.
Further, the release agent fine particles are preferably attached to the toner (colored resin particles) in an amount of 1 to 4% by weight.

As a method for obtaining the release agent fine particles, for example, there are the following methods. (1) Solvent a that dissolves the fluorinated surfactant and the release agent
And a are compatible with each other, but do not dissolve the fluorosurfactant and the release agent, the fluorosurfactant and the release agent are dissolved in a and then added to b which is stirred at high speed to cause precipitation. Method. (2) A method in which hot water is added to a liquid obtained by heat-melting a fluorine-based surfactant and a release agent while stirring at high speed, and the obtained dispersion liquid is cooled. (3) A method of dispersing a mixture of the fluorine-based surfactant and the release agent in a liquid c in which the fluorine-based surfactant and the release agent are not dissolved by using a dispersion device such as a ball mill. Further, these emulsions may contain a generally known surfactant as a dispersion stabilizer, a polymer dispersant, an inorganic ion, etc., alone or in combination.

The adhesion of the release agent fine particles to the colored resin particles is
It is also possible to dry mix the colored resin particles and the release agent fine powder, but since the release agent fine powder easily aggregates, uniform mixing is difficult. In order to uniformly attach the release agent particles to the surface of the colored resin particles, a method of adding and mixing the release agent dispersion liquid to the colorant particle dispersion liquid is preferable.

The release agent fine particles may be adhered to the colored resin particles simply by mixing, but they can be firmly adhered by any of the following methods. (1) A method of adjusting pH by adding acid or alkali. (2) A method of adding an anionic surfactant or a cationic surfactant. (3) A method of adding an electrolyte and the like. By appropriately setting the conditions by these methods, the potentials of the colored resin particles and the release agent particles in the dispersion liquid have opposite polarities, or even if the polarities are the same, the potential difference becomes large, and thus the release agent It is possible to produce a colored resin particle dispersion liquid in which fine particles are uniformly attached to the surface.

Release agent fine particles containing a fluorine-containing surfactant are uniformly adhered to the surface of the colored resin particles and then heat-treated to fix the fine particles to the toner surface. Heating 40 ~
By carrying out in the range of 60 ° C., a toner to which the fine particles are firmly attached can be obtained. After this heat treatment, the particles are separated by centrifugal sedimentation, suction filtration, etc., and the washing operation of redispersion and stirring in a mixed solvent such as water and methanol is performed several times, and the particles are separated and dried under reduced pressure to obtain a toner. To be

The toner thus obtained may be used as a mixture with a fluidizing agent. As the fluidizing agent, silica, hydrophobic silica,
Known materials such as titanium oxide, zinc oxide and zinc stearate are used. The amount of the fluidizing agent added is 0.1% to 5% by weight of the toner, preferably 0.5% to 3% by weight,
Is. As a mixing method, a general mixing device such as a V blender or a ball mill may be used.

When the toner of the present invention is used as a two-component developer, it is used as a mixture with a carrier.
As the carrier that can be used in the present invention, known carriers can be used, for example, iron, magnetite, hematite,
Examples thereof include magnetic powder such as ferrite and glass beads. The particle size of these powders is 30 μm to 500 μm. In particular, a carrier in which these powders are coated with a silicone resin is preferably used. Toner is added in an amount of 0.5% by weight to 5% by weight with respect to the carrier and mixed by the above-mentioned general mixing device to prepare a developer.

[0028]

EXAMPLES The present invention will be described in more detail below with reference to examples. The parts and% shown below are based on weight.

<Production Example of Resin Particle Dispersion> Methyl vinyl ether / maleic anhydride copolymer (weight average molecular weight 4
50,000) 7 parts by heating in 100 parts of methanol,
A dispersion stabilizer solution was obtained. Dispersion stabilizer solution 250 parts Styrene 60 parts Methyl acrylate 40 parts Dodecyl mercaptan 1 part 1,3-Butadiol dimethacrylate 1.5 In a four-necked flask equipped with a stirrer, a cooling pipe, a nitrogen introduction pipe, and a thermometer. Part, and purge the air completely with N ₂ gas to adjust the liquid temperature to 60.
C., 2.0 parts of 2,2′-azobisisobutyronitrile was added to initiate polymerization, and 100 r.p.m. p. Polymerization was carried out for 24 hours with stirring and rotation of m. The particle size distribution of the obtained resin particles measured by a Coulter Multisizer in a 20 μm Percher tube was 50,000, and the volume average particle size was 6.7 μm and the number average particle size was 6.6 μm.
The ratio was 1.02. The polymerization rate measured by the gravimetric method was 95.2%.

<Production Example of Colored Resin Particles> 6 parts of Oil Black 860 (manufactured by Orient Chemical Co., Ltd.) was added to the above resin particle dispersion and stirred at 50 ° C. for 2 hours, after which the dispersion was cooled to room temperature and spun down. The supernatant was removed, and re-dispersion in a mixed solvent of 50 parts of methanol and 50 parts of water was repeated three times, followed by washing, suction filtration, and drying under reduced pressure to obtain colored resin particles.

<Production Example (1) of Release Agent Fine Particle Dispersion Containing Fluorine Surfactant> Carnauba wax was placed in a sealable container equipped with an agitator, a cooling pipe and a dropping funnel, which was installed in an oil bath. (No. 1) 26 parts, fluorinated surfactant
(Florard FC171, manufactured by Sumitomo 3M Ltd.) 0.78 part was added, and the mixture was gradually heated and melt-mixed at 100 ° C., and then, while stirring, the nonionic surfactant polyoxyethylene nonylphenyl ether (average oxyethylene addition mole number = 1
5) Add 4 parts and dissolve completely. Then, stirring 9
After 70 parts of water at 8 ° C was gradually added and stirred for 1 hour, the mixture was allowed to cool to 25 ° C while stirring. After that, stirring was stopped, and after standing for 6 hours, the precipitate was removed, and the solid content concentration was adjusted to 30% with ion-exchanged water to obtain a release agent fine particle dispersion (1). The obtained release agent fine particle dispersion liquid is used as a dynamic light scattering meter DLS.
When measured with 700 (manufactured by Otsuka Electronics Co., Ltd.), the volume average particle diameter was 0.15 μm and the number average particle diameter was 0.11 μm.

<Production Examples (2) to (8) of Release Agent Fine Particle Dispersion Containing Fluorosurfactant> Except that the kind and amount of the fluorosurfactant were changed as shown in Table 1 below. A release agent fine particle dispersion liquid was produced in the same manner as in Production Example (1).

[0033]

[Table 1] Shows a slight melting.

<Production Example (9) of Fine Particle Dispersion Liquid for Release Agent> Paraffin wax (melting point 69.4 ° C.) 45 parts, sorbitan monostearate 2 parts, polyoxyethylene stearyl ether 3 parts and ion-exchanged water 60 parts It was weighed in a beaker, heated to 85 ° C. in a constant temperature water tank, stirred for 20 minutes with a homomixer, cooled, and diluted with ion-exchanged water to a solid content concentration of 30%. At this time, the wax fine particles had a volume average particle diameter of 0.18 μm and a number average particle diameter of 0.13 μm.

30 parts of the colored resin particles were added to 70 parts of a 50% aqueous methanol solution and dispersed. To this, 2.37 parts of the release fine particle dispersion liquid (1) containing a fluorine-based surfactant (solid content: 0.
71 parts) and stirred, 10 parts of 0.4% stearylamine acetate aqueous solution was added, and the mixture was heated and stirred at 50 ° C. for 30 minutes. After cooling this, it was centrifuged and sedimented, and the sedimented portion was dispersed in 100 parts of a 50% aqueous methanol solution, stirred at room temperature for 30 minutes, suction filtered and dried under reduced pressure to obtain a toner.

2 parts of this toner and 0.02 part of hydrophobic silica were mixed with a mixer. This was mixed with 98 parts of a silicone-coated ferrite carrier with a Turbula mixer to obtain a developer.

Examples 2 to 7 Toners were obtained in the same manner as in Example 1 except that the fluorine-containing surfactant-containing release agent fine particle dispersion liquid shown in Table 2 below was used in the amount shown in the same table. A developer was prepared in the same manner as in Example 1.

[0038]

[Table 2]

Comparative Examples 1 to 4 Toners were obtained in the same manner as in Example 1 except that the release agent fine particle dispersions shown in Table 3 below were used in the amounts shown in the same table.
Subsequently, a developer was prepared in the same manner as in Example 1.

[0040]

[Table 3]

(Evaluation) Using the developer obtained above, PP
C (Imagio 420, manufactured by Ricoh Co., Ltd.) was used to perform a copying test without applying a silicone oil as a release agent, and image evaluation and transfer rate measurement were performed. The results are shown in Table 4. The transfer rate was measured and the image was evaluated as follows.

Transfer rate: The entire surface is developed with black, the machine is stopped during the transfer, the toners of the untransferred area and the transferred area on the photosensitive member are transferred to an adhesive paper of known weight and constant area, the weight is measured, and the following formula is given. The transfer rate was defined as. Transfer rate = [(toner weight of untransferred portion−toner weight of transferred portion) / toner weight of untransferred portion] × 100

Releasing Property An all-black (black solid) image was copied, and the state of occurrence of nail marks on separate nails (length of nail marks) was evaluated on a scale of five. 5: No claw marks are generated 4: Claw marks less than 1 mm 3: Claw marks 1 m
m or more and less than 10 mm, 2: nail trace 10 mm or more and less than 20 mm, 1: nail trace 20 mm or more.

Fixability After fixing with the fixing device of IMAGEO 420 (constant conditions), a black solid image was put on a drawing tester, and the detached state of the image was evaluated on a scale of five. 5: Most of the drawn portion is not peeled off. 4: The drawn portion is peeled off like dots. 3: The drawn portion is peeled off in a broken line shape. 2: The drawn portion is completely peeled off, and the width of peeling is narrow. 1: The drawn portion is completely peeled off, and the peeling width is wide. The judgment is based on the limit sample.

Image Density The reflection density of a circular image having a diameter of 10 mm was measured with a Macbeth densitometer.

Image Sharpness The dot image was observed with an optical microscope, and the state of the image was evaluated on a five-point scale. 5: Toner exists only in the dot portion, and the contour is clear. 4: Most of the toner exists in the dot part, but the outline is slightly unclear. 3: A lot of toner is present in the dot portion, but the outline is unclear. 2: There is a large amount of toner scattering, but the presence of dots can be identified. 1: Toner scattering is large, and presence of dots cannot be determined. The judgment is based on the limit sample.

[0047]

[Table 4]

The following is found from Table 4. (1) In Examples, from Example 2, the transfer rate tends to decrease as the amount of the fluorine-based surfactant added increases. From Examples 4 and 7, when a fluorine-containing surfactant slightly soluble in water is used, the rank of nail marks is lowered. (2) In Comparative Example, from Comparative Examples 1 and 3, when the amount of wax is small, the transfer rate is relatively high, but the nail marks are insufficient. From Comparative Examples 2 and 4, when the amount of wax is increased and the nail mark is “rank 5”, the transfer rate is remarkably reduced.

[0049]

The electrostatic charge image developing toner according to claim 1 is obtained by fixing release agent fine particles containing a fluorine-based nonionic surfactant to the surface of thermoplastic resin particles containing a colorant. As a result, a sufficient releasing effect can be obtained by fixing a small amount of the releasing agent, so that the fluidity and transferability are excellent, and a clear image can be obtained with this toner.

In the toner for developing an electrostatic image according to claim 2, since the fluorine-based nonionic surfactant is water-insoluble, the releasability is further improved.

Claims (2)

[Claims] 1. A toner for developing an electrostatic charge image, comprising fine particles of a releasing agent containing a fluorine-based nonionic surfactant fixed to the surface of thermoplastic resin particles containing a colorant. 2. The toner for developing an electrostatic charge image according to claim 1, wherein the fluorine-based nonionic surfactant is water-insoluble.