JP3429986B2 - Polymerized toner and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymerized toner and a method for producing the same, and more specifically, a polymerized toner for developing an electrostatic latent image formed by an electrophotographic method, an electrostatic recording method and the like and a method for producing the same. Regarding the method. Further, the present invention is
The present invention relates to an image forming method using the polymerized toner and an image forming apparatus provided with the polymerized toner.

[0002]

2. Description of the Related Art In electrophotography and electrostatic recording, a developer for visualizing an electrostatic latent image is a two-component developer consisting of toner and carrier particles, and a carrier particle consisting essentially of toner. There are one-component developers that do not use.
The one-component developer includes a magnetic one-component developer containing magnetic powder and a non-magnetic one-component developer containing no magnetic powder. In the non-magnetic one-component developer, a fluidizing agent such as colloidal silica is often added independently in order to enhance the fluidity of the toner. As the toner, generally, colored particles obtained by dispersing a coloring agent such as carbon black or other additives in a binder resin and granulating the particles are used.

The toner manufacturing methods are roughly classified into a pulverization method and a polymerization method. In the pulverization method, a synthetic resin, a colorant and, if necessary, other additives are melt-mixed, pulverized, and then classified to obtain particles having a desired particle diameter to obtain a toner. In the polymerization method, a polymerizable monomer composition is prepared by uniformly dissolving or dispersing various additives such as a colorant, a polymerization initiator, and if necessary, a crosslinking agent and a charge control agent in the polymerizable monomer. Then, the mixture is dispersed in an aqueous dispersion medium containing a dispersion stabilizer with a stirrer to form fine droplet particles of the polymerizable monomer composition, and then the temperature is raised to carry out suspension polymerization. By doing so, a toner (polymerized toner) having a desired particle diameter is obtained.

In any of the developers, the electrostatic latent image is substantially developed with toner. Generally, in an image forming apparatus such as an electrophotographic apparatus or an electrostatic recording apparatus, image exposure is performed on a uniformly charged photoconductor to form an electrostatic latent image, and toner is attached to the electrostatic latent image. To form a toner image (visible image), transfer the toner image onto a transfer material such as transfer paper, and then transfer the unfixed toner image onto the transfer material by various methods such as heating, pressing, and solvent vapor. It is fixed. In the fixing step, in many cases, a transfer material on which a toner image is transferred is passed between a heating roll (fixing roll) and a pressure roll, and the toner is heated and pressure-bonded to be fused on the transfer material.

An image formed by an image forming apparatus such as an electrophotographic copying machine is required to have higher definition year by year. Conventionally, as a toner used in an image forming apparatus, a toner obtained by a pulverization method has been the mainstream. According to the pulverization method, colored particles having a wide particle size distribution are likely to be formed. Therefore, in order to obtain satisfactory development characteristics, it is necessary to classify the pulverized product and adjust the particle size distribution to a somewhat narrow particle size distribution. However, classification itself is complicated, and the yield is poor, and the yield of toner is significantly reduced. Therefore, in recent years, attention has been paid to polymerized toners whose particle size can be easily controlled and which does not require complicated manufacturing processes such as classification. According to the suspension polymerization method, a polymerized toner having a desired particle size and particle size distribution can be obtained without performing pulverization or classification. However, the conventional polymerized toner has a problem that it cannot sufficiently meet the recent demands for high speed copying, full-color copying, and energy saving.

In recent years, in electrophotographic copying machines, printers, etc., high-speed copying and high-speed printing are required along with reduction of power consumption. In the electrophotographic method, a particularly energy-consuming step is a fixing step after transferring toner from a photoconductor onto a transfer material such as transfer paper. In the fixing step, a heating roll heated to a temperature of 150 ° C. or higher is usually used to heat and fuse the toner to fix it on the transfer material, and electric power is used as an energy source thereof. Lowering the heating roll temperature is required from the viewpoint of energy saving. In order to lower the heating roll temperature, it is necessary to fix the toner at a lower temperature than before. That is, it is necessary to lower the fixing temperature of the toner itself. If you use a toner that can be fixed at a lower temperature than before, you can lower the heating roll temperature, but if you do not lower the heating roll temperature so much, the fixing time can be shortened, making it suitable for high-speed copying and high-speed printing. Can respond.

In designing the toner, the glass transition temperature of the binder resin constituting the toner may be lowered in order to meet the demands from the image forming apparatus such as energy saving and high speed copying. However, when the toner is composed of a binder resin having a low glass transition temperature, the toners are likely to block each other during storage or transportation, or in the toner box of the image forming apparatus to easily form an aggregate,
The toner becomes so-called poor storage stability.

In recent years, it has been required that color copying and color printing can be clearly performed by the electrophotographic method. For example, in full-color copying, it is not sufficient to simply melt and soften the toner and fuse it onto the transfer material in the fixing step, and it is necessary to uniformly melt and mix the toners of respective colors. . In particular, since color images are often used on OHP (overhead projector) sheets for presentations at various conferences, it is required that toner images fixed on the sheets have excellent OHP transparency. It has become. To satisfy the OHP transparency, the toner is required to be uniformly melted on the transparent synthetic resin OHP sheet.
For that purpose, it is necessary to design the melt viscosity near the fixing temperature of the toner to be lower than that of the conventional one. As a method of lowering the melt viscosity of the toner, there are methods such as lowering the molecular weight of the binder resin and lowering the glass transition temperature as compared with the conventional binder resin for toner. However, no matter which method is adopted, the toner is apt to cause blocking, and the toner has poor storage stability.

Conventionally, as a method for obtaining a polymerized toner having excellent fixability, for example, in JP-A-3-136065, a polymerizable monomer containing a colorant and a charge control agent is added in the presence of a macromonomer. A method of suspension polymerization has been proposed. A macromonomer is a relatively long linear molecule having a polymerizable functional group at the end of the molecular chain, for example, an unsaturated group such as a carbon-carbon double bond. According to this method, since the macromonomer is incorporated as a monomer unit in the molecular chain of the produced polymer, a large number of branches due to long linear molecules of the macromonomer are generated in the molecular chain. The resulting polymer is entangled with its branches, so-called physical crosslinking,
Since it is apparently a high molecular weight polymer, the offset resistance of the polymerized toner is improved. On the other hand, physical crosslinking with a macromonomer component is different from chemical crosslinking with a crosslinkable monomer such as divinylbenzene and has a loose crosslinking structure, so that the crosslinking structure is easily broken by heating. Therefore, this polymerized toner is easily melted at the time of fixing using a heating roll, and thus has excellent fixability. However, this polymerized toner is not satisfactory in terms of storability because the toner particles tend to aggregate during storage.

As described above, according to the conventional method for lowering the fixing temperature of the toner and improving the uniform melting property, the fixing property of the obtained toner is improved, but the storage property is deteriorated, which is an inverse correlation. Will occur. As a method of solving this inverse correlation, a toner composed of a binder resin having a low glass transition temperature is coated with a polymer having a high glass transition temperature to improve blocking resistance, thereby solving the problem of storage stability. A so-called capsule type toner has been proposed.

As a method for producing a capsule type toner, for example, in JP-A-60-173552, a jet mill device is used to form a coloring agent or magnetic particles on the surface of spherical core particles having a fine particle diameter. A method of forming a coating layer composed of a conductive agent and a binder resin has been proposed. A thermoplastic transparent resin such as an acrylic ester resin or a styrene resin is used as the core particles. In this publication, it is reported that a toner having a multi-layer structure having excellent fluidity and improved functionality can be obtained by this method. However, in this method, when the core particles having a low glass transition temperature are used, the core particles themselves tend to agglomerate. Further, according to this method, the film thickness of the binder resin attached to the core particles tends to increase. Therefore, with this method, it is difficult to obtain a toner having improved fixability and uniform meltability while maintaining storability.

In JP-A-2-259657, crosslinked toner particles prepared by suspension polymerization are added to a solution prepared by dissolving an encapsulating polymer, a charge control agent and a release agent in an organic solvent. Then, a method for producing an electrophotographic toner is proposed in which a poor solvent is added to form a coating of an encapsulating polymer containing a charge control agent and a release agent on the surface of the crosslinked toner particles. However, in this method, the solubility of the encapsulating polymer is reduced by dropping the poor solvent and the polymer is deposited on the surface of the crosslinked toner particles, so that it is difficult to obtain true spherical particles. In this method, the capsule wall formed on the surface of the crosslinked toner particles has a nonuniform thickness and is relatively thick. As a result, the effect of improving the developability and fixability is not sufficient.

In JP-A-57-45558, the core particles formed by polymerization are mixed and dispersed in a latex aqueous solution of 1 to 40% by weight, and then a water-soluble inorganic salt is added to the core particle surface. A method for producing a toner for developing an electrostatic charge image, which forms a coating layer of fine particles obtained by emulsion polymerization, has been proposed. However, this method has a drawback that the charging characteristics of the toner greatly depend on the environment due to the influence of the surfactant and the inorganic salt remaining on the fine particles, and the charging is lowered particularly under the condition of high temperature and high humidity. .

In JP-A-61-118758, a composition containing a vinyl-based monomer, a polymerization initiator and a coloring agent is suspension polymerized to obtain core particles. Has hydrophilicity equal to or higher than that of the resin contained in the core particles, and
A method for producing a toner is disclosed in which a vinyl-based monomer that gives a polymer having a glass transition temperature higher than the glass transition temperature of the resin is polymerized to form a shell. In this method, a vinyl-based monomer for forming a shell is adsorbed and grown on the core particle, so that the vinyl-based monomer absorbed even inside the core particle is polymerized to form a clear core. It is often difficult to form a shell structure. So with this method,
It is difficult to obtain a toner having sufficiently improved storability.
Further, in this method, in order to clarify the core / shell structure and improve the storage stability, the thickness of the shell had to be increased.

[0015]

SUMMARY OF THE INVENTION An object of the present invention is to provide a polymerized toner having a low fixing temperature and a uniform melting property, and excellent in storage stability (blocking resistance), and a method for producing the same. Another object of the present invention is to provide a polymerized toner capable of coping with speeding up of copying and printing, full colorization, and energy saving, and a method for producing the same. Further, it is an object of the present invention to provide a polymerized toner capable of forming a toner image showing excellent transparency (OHP transparency) when printed and fixed on an OHP sheet, and a method for producing the same. is there. Another object of the present invention is to
An object is to provide an image forming method using a polymerized toner having such excellent characteristics, and an image forming apparatus containing the toner.

The inventors of the present invention have conducted extensive studies to overcome the above-mentioned problems of the prior art, and as a result, contain a colorant and a polymerizable monomer capable of forming a polymer having a glass transition temperature of 70 ° C. or less. The composition is subjected to suspension polymerization in the presence of a macromonomer to prepare colored polymer particles, and then the colored polymer particles are used as core particles to form the core particles in the presence of the core particles. Suspension polymerization of a polymerizable monomer capable of forming a polymer having a glass transition temperature higher than that of the polymer component, to form a shell composed of a polymer layer coating the core particles It has been found that an excellent core / shell type polymerized toner can be obtained.

In the polymerized toner of the present invention, the fixing temperature can be lowered by the core particles containing the polymer component having a low glass transition temperature, the uniform melting property can be improved, and the speed of copying or printing can be increased. It is possible to meet the demands for full color, OHP transparency and the like. In addition, the polymerized toner of the present invention can coat the core particles with an extremely thin shell, and therefore exhibits good storage stability (blocking resistance), and is sufficient for various requirements such as fixability and uniform meltability. I can respond. The present invention has been completed based on these findings.

[0018]

Thus, according to the present invention, the following respective inventions are provided. 1. In an aqueous dispersion medium containing a dispersant, at least
Can form a polymer with a colorant and a glass transition temperature of 70 ° C or less
A polymerizable monomer composition containing a core polymerizable monomer
The volume average particle diameter (dv) obtained by suspension polymerization in the presence of a macromonomer is 0.5 to 20 μm, and the ratio of the volume average particle diameter (dv) to the number average particle diameter (dp) (dv / dp)
Core particles but comprising a colored polymer particles less than or equal to 1.7, the
Suspension polymerization of shell polymerizable monomers in the presence of core particles
The glass of the polymer component constituting the core particles obtained by
Core-shell type having a glass transition temperature higher than the transition temperature, a shell made of a polymer layer having an average film thickness of 0.005 to 0.05 μm , and having a toluene insoluble content of 50% or less. Structure suspension polymerized toner. 2. (1) A polymerizable monomer composition containing at least a colorant and a polymerizable monomer for core capable of forming a polymer having a glass transition temperature of 70 ° C. or less in an aqueous dispersion medium containing a dispersant. Suspension polymerization in the presence of a macromonomer, the volume average particle diameter (dv) is 0.5 to 20 μm, and the ratio of the volume average particle diameter (dv) to the number average particle diameter (dp) (dv / dp). )
Of a colored polymer particle having a ratio of 1.7 or less, and then (2) in the presence of the core particle, a glass transition temperature higher than the glass transition temperature of the polymer component constituting the core particle. the average film thickness capable of forming a polymer by suspension polymerization of a polymerizable monomer for shell, covering the core particles with
A method for producing a suspension-polymerized toner having a core-shell type structure, in which a toluene-insoluble content forming a shell composed of a polymer layer having a thickness of 0.005 to 0.05 μm is 50% or less.

3. An image forming method including a step of attaching a toner to a surface of a photoconductor on which an electrostatic latent image is formed to form a visible image, and then transferring the visible image to a transfer material, containing a dispersant as the toner. At least in an aqueous dispersion medium
Also forms a polymer with a colorant and glass transition temperature below 70 ° C
Polymerizable monomer composition containing a polymerizable monomer for core
Obtained by suspension polymerization in the presence of a macromonomer has a volume average particle diameter (dv) of 0.5 to 20 μm, a volume average particle diameter (dv) and a number average particle diameter (dp). ) And (dv / d
A core particle composed of colored polymer particles having a p) of 1.7 or less has a polymerizable monomer for shell suspended in the presence of the core particle.
Of the polymer component constituting the core particles obtained by polymerization
A core / shell having a glass transition temperature higher than the glass transition temperature, a shell made of a polymer layer having an average film thickness of 0.005 to 0.05 μm , and having a toluene insoluble content of 50% or less. An image forming method comprising using a suspension polymerization toner having a mold structure. 4. A photoreceptor, a means for charging the surface of the photoreceptor, a means for forming an electrostatic latent image on the surface of the photoreceptor, a means for containing toner,
Toner is stored in an image forming apparatus including a unit that supplies the toner and develops an electrostatic latent image on the surface of the photoconductor to form a toner image, and a unit that transfers the toner image from the surface of the photoconductor to a transfer material. Means, Aqueous dispersion medium containing dispersant
Among them, at least the colorant and the glass transition temperature are below 70 ° C.
Polymerization with a core-forming polymerizable monomer capable of forming a polymer
Polymerization of a reactive monomer composition in the presence of macromonomer
The volume average particle diameter (dv) obtained by
And a core particle made of a colored polymer particle having a ratio (dv / dp) of the volume average particle diameter (dv) to the number average particle diameter (dp) of 1.7 or less is used for a shell in the presence of the core particle. Polymerizable
The weight of the core particles, which is obtained by suspension polymerization of the monomer,
A glass transition temperature higher than the glass transition temperature of the combined component
And a shell composed of a polymer layer having an average film thickness of 0.005 to 0.05 μm and having a toluene insoluble content of 5
An image forming apparatus containing a suspension-polymerized toner having a core-shell type structure of 0% or less.

Further, according to the present invention, the following preferred embodiments are provided. 5. First, the core particles are colored polymer particles obtained by suspension polymerization of a polymerizable monomer composition containing at least a colorant and a polymerizable monomer for core in the presence of a macromonomer. Item 7. The polymerized toner according to item. 6. 6. The polymerized toner according to item 5, wherein the polymerizable monomer composition further contains a crosslinkable monomer. 7. 2. The polymerized toner according to item 1, wherein the shell is a polymer layer formed by suspension polymerization of a polymerizable monomer for shell in the presence of core particles. 8. 8. The polymerized toner according to item 7, wherein the shell is a polymer layer formed by suspension-polymerizing a polymerizable monomer for shell with a charge control agent in the presence of core particles.

9. 2. The polymerized toner according to item 1, wherein the glass transition temperature of the polymer component forming the shell is higher than the glass transition temperature of the polymer component forming the core particle. 10. 2. The polymerized toner according to item 1, wherein the ratio (rl / rs) of the major axis (rl) and the minor axis (rs) of the polymerized toner is 1 to 1.2. 11. 2. The polymerized toner according to item 1, wherein the toluene insoluble content of the polymerized toner is 30 % by weight or less. 12. 3. The method according to item 2, wherein the polymerizable monomer composition also contains a crosslinkable monomer. 13. 3. The method according to item 2, wherein the polymerizable monomer for core contains a styrene-based monomer and a derivative of (meth) acrylic acid.

14. Thirteenth, wherein the polymerizable monomer for core contains styrene and n-butyl acrylate
The manufacturing method according to item. 15. 14. The method according to Item 13, wherein the polymerizable monomer for core contains styrene and 2-ethylhexyl acrylate. 16. 3. The method according to item 2, wherein the macromonomer has a (meth) acryloyl group at the molecular chain end. 17. Item 17. The production method according to Item 16, wherein the macromonomer is a polymer of (meth) acrylic acid ester. 18. Macromonomer has a number average molecular weight of 1,000 to 3
3. The method according to item 2, which has a content of 10,000.

19. 3. The method according to item 2, wherein the macromonomer has a glass transition temperature higher than the glass transition temperature of the polymer obtained by polymerizing the polymerizable monomer for core. 20. In the step (1), the core polymerizable monomer 1
0.01 to 10 parts by weight of macromonomer
3. The production method according to item 2, which is present in a ratio of parts by weight. 21. 3. The production method according to item 2, wherein in the step (1), the polymerizable monomer composition is suspension-polymerized with an oil-soluble radical initiator in an aqueous dispersion medium in the presence of a macromonomer. 22. Item 22. The production method according to Item 21, wherein the oil-soluble radical initiator is an organic peroxide having a 10-hour half-life temperature of 60 to 80 ° C and a molecular weight of 250 or less.

23. The production method according to item 2, wherein in the step (1), suspension polymerization is carried out in an aqueous dispersion medium containing a colloid of a hardly water-soluble metal hydroxide as a dispersant. 24. The 50% cumulative value (D ₅₀ ) of the number particle size distribution of the poorly water-soluble metal hydroxide colloid is 0.5 μm or less, and the 90% cumulative value (D ₉₀ ) of the number particle size distribution is 1 μm.
24. The manufacturing method according to Item 23, which is as follows. 25. Item 24. The method according to Item 23, wherein the poorly water-soluble metal hydroxide colloid is a poorly water-soluble metal hydroxide colloid obtained by adjusting the pH of the aqueous solution of the water-soluble polyvalent metal compound to 7 or more. 26. The slightly water-soluble metal hydroxide colloid is a slightly water-soluble metal hydroxide colloid obtained by reacting a water-soluble polyvalent metal compound and an alkali metal hydroxide in an aqueous phase.
The manufacturing method according to item.

27. In the step (1), a mixed solution containing at least a colorant, a polymerizable monomer for core, a macromonomer, and a radical initiator is prepared, and then this mixed solution is placed in an aqueous dispersion medium containing a dispersant. To the
The production method according to the second item, wherein the suspension polymerization is carried out at a temperature of 30 to 200 ° C. after granulating into fine liquid droplets by stirring. 28. Volume average particle diameter (dv) in the step (1)
Is 0.5 to 20 μm, and the ratio (dv / dp) of the volume average particle diameter (dv) to the number average particle diameter (dp) is 1.7 or less. The manufacturing method according to item. 29. 3. The production method according to item 2, wherein in the step (2), the polymerizable monomer for shell is made into droplets having a number average particle size smaller than that of the core particles, and suspension polymerization is performed. 30. The method according to item 2, wherein the polymerizable monomer for shell has a solubility in water at 20 ° C. of 0.1% by weight or more.

31. The polymerizable monomer for shell is a monomer having a solubility in water at 20 ° C. of less than 0.1% by weight,
The production method according to item 2, wherein in the step (2), the polymerizable monomer for shell and an organic solvent having a solubility in water at 20 ° C. of 5% by weight or more are added to carry out suspension polymerization. 32. The production method according to item 2, wherein in the step (2), the shell polymerizable monomer and the charge control agent are added to carry out suspension polymerization. 33. The method according to item 2, wherein in the step (2), the polymerizable monomer for shell is suspension-polymerized with a water-soluble radical initiator. 34. In the step (2), the average film thickness is 0.005 to 0.005.
Second to form a shell consisting of 0.07 μm polymer layer
The manufacturing method according to item.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION The polymerized toner of the present invention comprises a core comprising core particles and a shell covering the core particles.
It has a shell-type structure. In the polymerized toner of the present invention, the core particles have a volume average particle diameter (dv) of 0.5.
The range is -20 μm, preferably 1-10 μm. If the core particles are too large, the resolution of the image tends to decrease. The volume average particle diameter (dv) / number average particle diameter (dp) of the core particles is 1.7 or less, preferably 1.5 or less. If this ratio exceeds 1.7, the image resolution tends to decrease. In the polymerized toner of the present invention, the average film thickness of the shell is 0 . 005~0.07 μm, is good Mashiku 0.
It is in the range of 005 to 0.05 μm. If the thickness of the shell is too large, the fixability will decrease, and if it is too small, the storability will decrease.

When the particle size of the core particles and the shell thickness of the polymerized toner having the core / shell structure can be observed by an electron microscope, the particle size and the shell thickness randomly selected from electron micrographs are directly used. It can be obtained by measuring. If it is difficult to observe the particle size of the core particles and the thickness of the shell by an electron microscope, at the stage of forming the core particles, or measure the particle size of the core particles in the same manner as described above using an electron microscope, Alternatively, it is measured using a Coulter counter, and then the shell is coated on the core particles, and then the particle size of the resulting polymerized toner is measured using an electron microscope or a Coulter counter to determine the change in particle size before and after coating the shell. From this, the average thickness of the shell can be determined. If these methods are difficult, from the amount of the polymerizable monomer used to form the core particles, and the amount of the polymerizable monomer used to form the shell, the average particle size of the core particles and the shell The film thickness can be calculated.

The polymerized toner of the present invention has a toluene insoluble content of usually 50% by weight or less, preferably 40% by weight or less, more preferably 30% by weight or less. When the amount of toluene-insoluble matter increases, the fixability tends to decrease.
Toluene insoluble matter means the polymer component forming the polymerized toner is put in a wire mesh basket of 80 mesh, immersed in toluene at room temperature for 24 hours, and then the weight of the solid matter remaining in the basket is measured to determine the polymer component. It is expressed in% by weight with respect to.

The polymerized toner of the present invention has a major axis (rl).
And the minor axis (rs) ratio (rl / rs) is usually 1 to 1.
2, preferably in the range of 1-1.15. When this ratio becomes large, the resolution of the image decreases, and when the polymerized toner is stored in the toner storage portion of the image forming apparatus, friction between the toners becomes large, so that additives such as a fluidizing agent peel off. As a result, the durability tends to decrease.

In the analysis using a differential scanning calorimeter (DSC), the polymerized toner of the present invention usually shows a peak I between 0 ° C. and 80 ° C. in the first scanning, and from the peak I. Peak II appears in the higher temperature range. In the second scan, one peak appears at 0 to 90 ° C. and no peak appears in the higher temperature range. Peak I
The temperature difference between peak II and peak II is usually 20 ° C. or higher. The polymerized toner having two peaks in this way has a good balance between storage stability and fixability.

The polymerized toner of the present invention is a polymer containing at least a colorant and a polymerizable monomer for core capable of forming a polymer having a glass transition temperature of 70 ° C. or lower in an aqueous dispersion medium containing a dispersant. The polymerizable monomer composition is suspension-polymerized in the presence of a macromonomer to prepare core particles composed of colored polymer particles [step (1)], and then the core particles are added in the presence of the core particles. Suspension polymerization of a polymerizable monomer for shell capable of forming a polymer having a glass transition temperature higher than the glass transition temperature of the polymer component constituting the particle, and a shell comprising a polymer layer coating the core particle Are formed [step (2)]
It can be manufactured by a method.

The polymerizable monomer for core used in the present invention has a glass transition temperature of 70 ° C. or lower, preferably 10 to 60 ° C.
More preferably, it is capable of forming a polymer at 15 to 50 ° C. The polymerizable monomer for core may be used singly or in combination of two or more. If the polymerizable monomer for the core is capable of forming a glass transition temperature of more than 70 ° C., the fixing temperature of the polymerized toner becomes high, the OHP permeability is lowered, and it becomes unsuitable for speeding up copying and printing.

The glass transition temperature (Tg) of a polymer is a calculated value (referred to as calculated Tg) calculated according to the type of monomer used and the proportion used. When one type of monomer is used, the Tg of the homopolymer formed from the monomer is
Is defined as the Tg of the polymer in the present invention. For example,
Since Tg of polystyrene is 100 ° C., when styrene is used alone as a monomer, the monomer is
It is said that g forms a polymer having a temperature of 100 ° C. When two or more kinds of monomers are used and the resulting polymer is a copolymer, the Tg of the copolymer is calculated according to the kind and the ratio of the used monomers. For example, as monomers, 70% by weight of styrene and 30 of n-butyl acrylate are used.
When using wt%, the Tg of the styrene-n-butyl acrylate copolymer produced at this monomer ratio is 35 ° C.
Therefore, this monomer is said to form a polymer having a Tg of 35 ° C.

Further, the definition of "a core polymerizable monomer capable of forming a polymer having a glass transition temperature of 70 ° C. or lower" means that when a plurality of monomers are used, each of the monomers is Tg
It does not mean that it must form a polymer below 70 ° C. When one type of monomer is used, the T of homopolymer formed from the monomer is used.
g must be below 70 ° C. However, when two or more kinds of monomers are used, the Tg of the copolymer formed from the monomer mixture may be 70 ° C. or lower, and the Tg of the polymer alone in the monomer is Those exceeding 70 ° C. may be included. For example, the styrene homopolymer has a Tg of 100 ° C., but when styrene is mixed with a monomer forming a polymer having a low Tg (for example, n-butyl acrylate), the Tg is 70 ° C. or less. If a copolymer can be formed, styrene can be used as one of the core polymerizable monomers.

In the present invention, as the polymerizable monomer for the core,
Usually, vinyl monomers are used. The Tg of the polymer is adjusted to a desired range by using each of the various vinyl monomers alone or in combination of two or more. Examples of the vinyl-based monomer used in the present invention include styrene-based monomers such as styrene, vinyltoluene, and α-methylstyrene; acrylic acid, methacrylic acid;
Methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, dimethylaminoethyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate,
Derivatives of (meth) acrylic acid such as dimethylaminoethyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide; ethylene,
Ethylenically unsaturated monoolefins such as propylene and butylene; vinyl halides such as vinyl chloride, vinylidene chloride and vinyl fluoride; vinyl esters such as vinyl acetate and vinyl propionate; vinyl ethers such as vinyl methyl ether and vinyl ethyl ether; vinyl. Examples thereof include vinyl ketones such as methyl ketone and methyl isopropenyl ketone; nitrogen-containing vinyl compounds such as 2-vinylpyridine, 4-vinylpyridine and N-vinylpyrrolidone; and the like. These vinyl-based monomers may be used alone or in combination of a plurality of monomers.

Among these, as the polymerizable monomer for the core, a combination of a styrene-based monomer and a (meth) acrylic acid derivative is preferably used. Preferred specific examples include a combination of styrene and butyl acrylate (that is, n-butyl acrylate) and styrene and 2-ethylhexyl acrylate (that is, 2-ethylhexyl acrylate).

As the polymerizable monomer for the core, it is preferable to use a crosslinkable monomer together with these vinyl monomers from the viewpoint of improving the storage stability of the polymerized toner. Examples of the crosslinkable monomer include aromatic divinyl compounds such as divinylbenzene, divinylnaphthalene, and their derivatives; ethylene glycol dimethacrylate,
Examples thereof include diethylenically unsaturated carboxylic acid esters such as diethylene glycol dimethacrylate; divinyl compounds such as N, N-divinylaniline and divinyl ether; compounds having three or more vinyl groups; and the like. These crosslinkable monomers may be used alone or in combination of two or more. In the present invention, the crosslinkable monomer is the polymerizable monomer 100 for the core.
It is desirable to use 0.01 to 5 parts by weight, preferably 0.05 to 2 parts by weight, relative to parts by weight.

The macromonomer (also referred to as macromer) used in the present invention is a relatively long linear molecule having a polymerizable functional group (for example, an unsaturated group such as a carbon-carbon double bond) at the end of the molecular chain. Is. As a macromonomer,
An oligomer or polymer having a vinyl polymerizable functional group at the terminal of the molecular chain and having a number average molecular weight of usually 1,000 to 30,000 is preferable. When a macromonomer having a small number average molecular weight is used, the surface portion of the polymerized toner becomes soft and the storage stability tends to be lowered. On the other hand, when a macromonomer having a large number average molecular weight is used, the fluidity of the macromonomer deteriorates, and the fixability and storability deteriorate. Examples of the vinyl polymerizable functional group at the terminal of the molecular chain of the macromonomer include an acryloyl group and a methacryloyl group, and a methacryloyl group is preferable from the viewpoint of easy copolymerization.

The macromonomer used in the present invention preferably has a glass transition temperature higher than the glass transition temperature of the polymer obtained by polymerizing the polymerizable monomer for core. The level of Tg between the polymer obtained by polymerizing the polymerizable monomer for core and the macromonomer is relative. For example, when the polymerizable monomer for core forms a polymer having Tg of 70 ° C, the macromonomer may have a Tg of more than 70 ° C. When the polymerizable monomer for core forms a polymer having Tg = 20 ° C., the macromonomer may be, for example, Tg = 60 ° C.
It may be one. The Tg of the macromonomer is a value measured by a normal measuring device such as DSC.

As the macromonomer used in the present invention,
For example, a polymer obtained by polymerizing styrene, a styrene derivative, a methacrylic acid ester, an acrylic acid ester, acrylonitrile, methacrylonitrile or the like alone or by polymerizing two or more kinds; a macromonomer having a polysiloxane skeleton; No. 203746, pages 4 to 7
The thing etc. which are disclosed by the page can be mentioned. Of these macromonomers, hydrophilic ones, particularly polymers obtained by polymerizing methacrylic acid esters or acrylic acid esters alone or in combination, are suitable for the present invention.

The amount of macromonomer used is usually 0.01 to 10 parts by weight, preferably 0.03 to 5 parts by weight, and more preferably 0.05 to 100 parts by weight, based on 100 parts by weight of the polymerizable monomer for core. 1 part by weight. When the amount of the macromonomer used is small, it is difficult to improve storage stability and fixability in a well-balanced manner. As the amount of macromonomer used increases,
The fixability tends to decrease.

In the present invention, the core particle is prepared by suspension polymerization of the above-mentioned polymerizable monomer for core, macromonomer and, if necessary, crosslinkable monomer. The suspension polymerization is carried out in an aqueous dispersion medium containing a dispersant. More specifically,
Suspension polymerization is usually performed by mixing a colorant, a polymerizable monomer for core, a macromonomer, a radical polymerization initiator, and optionally a crosslinkable monomer, and other additives, and uniformly dispersing them by a ball mill or the like. To prepare a mixed solution, then, the mixed solution is put into an aqueous dispersion medium containing a dispersant,
After being dispersed using a mixing device having a high shearing force and granulated into fine droplets, suspension polymerization is usually performed at a temperature of 30 to 200 ° C.

The dispersant preferably used in the present invention is a colloid of a poorly water-soluble metal compound. Slightly water-soluble metal compounds include sulfates such as barium sulfate and calcium sulfate; carbonates such as barium carbonate, calcium carbonate and magnesium carbonate; phosphates such as calcium phosphate; metal oxides such as aluminum oxide and titanium oxide; water. Examples thereof include metal hydroxides such as aluminum oxide, magnesium hydroxide and ferric hydroxide. Of these, the sparingly water-soluble metal hydroxide colloid is preferable because it can narrow the particle size distribution of the polymer particles produced and improves the sharpness of the image. In particular, when the cross-linkable monomer is not copolymerized, the use of a poorly water-soluble metal hydroxide colloid as the dispersant can improve the fixability and storability of the polymerized toner.

The poorly water-soluble metal hydroxide colloid is not limited by its production method, but is obtained by adjusting the pH of the aqueous solution of the water-soluble polyvalent metal compound to 7 or more. Colloids, particularly poorly water-soluble metal hydroxide colloids formed by the reaction of a water-soluble polyvalent metal compound and an alkali metal hydroxide in an aqueous phase, are preferred. The colloid of the poorly water-soluble metal compound used in the present invention has a number particle size distribution D ₅₀ (50% cumulative value of the number particle size distribution) of 0.5 μm or less and a D ₉₀ (90% cumulative value of the number particle size distribution). Is preferably 1 μm or less. When the particle size of this colloid becomes large, the stability of suspension polymerization is impaired.

The dispersant is usually used in a proportion of 0.1 to 20 parts by weight with respect to 100 parts by weight of the polymerizable monomer for core. When the amount of the dispersant used is too small, it is difficult to obtain sufficient polymerization stability, and polymer aggregates are easily generated. On the other hand, if the amount of the dispersant used is too large, the viscosity of the aqueous dispersion medium increases too much and small droplets cannot be formed, which is not preferable. In the present invention, as a dispersant, if necessary,
Water-soluble polymers can be used. Examples of the water-soluble polymer include polyvinyl alcohol, methyl cellulose, gelatin and the like. In the present invention,
Although it is not necessary to use a surfactant, a small amount of a surfactant can be used in order to stably carry out suspension polymerization within a range in which the environmental dependence of the charging characteristics does not become large.

As radical polymerization initiators, persulfates such as potassium persulfate and ammonium persulfate; 4,4-azobis (4-cyanovaleric acid), dimethyl-2,2'-azobis (2-methylpropionate) ), 2,2-azobis (2-amidinopropane) dihydrochloride, 2,2-azobis-2-methyl-N-1,1-bis (hydroxymethyl) -2-hydroxyethylpropioamide, 2,2 ′
-Azobis (2,4-dimethylvaleronitrile), 2,
Azo compounds such as 2'-azobisisobutyronitrile and 1,1'-azobis (1-cyclohexanecarbonitrile); methyl ethyl peroxide, di-t-butyl peroxide, acetyl peroxide, dicumyl peroxide, lauroyl peroxide, benzoyl Peroxide, t-butylperoxy-2-ethylhexanoate, di-isopropylperoxydicarbonate, di-
Examples thereof include peroxides such as t-butylperoxyisophthalate.

Among these radical polymerization initiators, oil-soluble radical initiators are preferable, and particularly, the 10-hour half-life temperature is 60 to 80 ° C., preferably 65 to 80 ° C., and the molecular weight is 250 or less. Oil-soluble radical initiators selected from peroxides are preferred. Among the oil-soluble radical initiators, t-butylperoxy-2-ethylhexanoate has a small odor during printing of the polymerized toner,
It is particularly preferable because it causes less environmental damage due to volatile components such as odor. The amount of the polymerization initiator used is usually 0.001 to 3% by weight based on the aqueous medium. When the amount of the polymerization initiator used is less than 0.001% by weight, the polymerization rate is slow, and 3
Exceeding weight% is not economical.

The polymerized toner of the present invention contains a colorant. The colorant is added to the core particles. If desired, the shell may also contain a colorant. Examples of colorants include dyes and pigments such as carbon black, nigrosine base, aniline blue, chalco oil blue, chrome yellow, ultramarine blue, orient oil red, phthalocyanine blue, and malachite green oxalate; cobalt, nickel, and trioxide. Magnetic particles of iron, ferrosoferric oxide, manganese oxide, zinc oxide, nickel oxide, and the like; The dye or pigment is usually 0.1 to 20 parts by weight, preferably 1 to 100 parts by weight of the polymerizable monomer for the core.
It is used in a proportion of from 10 to 10 parts by weight. The magnetic particles are usually 1 to 100 parts by weight with respect to 100 parts by weight of the polymerizable monomer for core.
It is used in a proportion of parts by weight, preferably 5 to 50 parts by weight.

In the present invention, various additives such as a molecular weight modifier and a release agent may be mixed with the polymerizable monomer for core, if necessary. Examples of the molecular weight modifier include mercaptans such as t-dodecyl mercaptan, n-dodecyl mercaptan and n-octyl mercaptan; halogenated hydrocarbons such as carbon tetrachloride and carbon tetrabromide. These molecular weight modifiers can be added before the start of the polymerization or during the polymerization. The molecular weight modifier is a polymerizable monomer for core 10
It is usually used in an amount of 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight, relative to 0 parts by weight.

Examples of the releasing agent include low molecular weight polyolefins such as low molecular weight polyethylene, low molecular weight polypropylene and low molecular weight polybutylene; paraffin waxes; higher fatty acids, and higher fatty acid compounds such as esters or metal salts thereof, etc. Can be mentioned. The release agent is usually used in a proportion of 0.1 to 20 parts by weight, preferably 1 to 10 parts by weight, based on 100 parts by weight of the polymerizable monomer for core. Lubricants such as oleic acid and stearic acid for the purpose of uniformly dispersing the colorant in the core particles;
A dispersion aid such as a silane or titanium coupling agent may be used. Such a lubricant or dispersant is usually 1 / 1000-based on the weight of the colorant.
It is used at a ratio of about 1/1.

The suspension polymerization for obtaining the core particles is carried out until the polymerization conversion rate of the monomer is usually 80% or more, preferably 85% or more, more preferably 90% or more. When the polymerization conversion rate is less than 80%, a large amount of the polymerizable monomer for the core remains, so even if the polymerizable monomer for the shell is added and polymerized, the polymerizable monomer for the shell is Since the copolymer of the polymer and the polymerizable monomer for the core covers the surface of the core particle, the difference in Tg between the core particle and the shell becomes small, and the storage stability of the polymerized toner is likely to decrease. The polymerized toner of the present invention can be obtained by suspension-polymerizing the polymerizable monomer for shell in the presence of the core particles.

In the present invention, as the polymerizable monomer for shell, one capable of forming a polymer having a glass transition temperature higher than the glass transition temperature of the polymer component of the core particle is used. Here, the height of each Tg is relative. As the polymerizable monomer for the shell, a monomer such as styrene or methyl methacrylate, which forms a polymer having a glass transition temperature of more than 70 ° C., is used alone, or 2
It is preferable to use a combination of two or more species. When the glass transition temperature of the polymer obtained by the polymerizable monomer for the core or the polymer component of the core particles is much lower than 70 ° C., the polymerizable monomer for the shell has a glass transition temperature of 7 or less.
It may form a polymer at 0 ° C or lower. However, the glass transition temperature of the polymer composed of the polymerizable monomer for shell needs to be set higher than the glass transition temperature of the polymer component of the core particles.

The glass transition temperature of the polymer obtained from the polymerizable monomer for shell is usually 50 to 120 ° C., preferably 60 to 1 in order to improve the storability of the polymerized toner.
The temperature is set to 10 ° C, more preferably 70 ° C to 105 ° C. If the glass transition temperature of the polymer composed of the polymerizable monomer for the shell is too low, the preservability of the polymerized toner is lowered even if the glass transition temperature is higher than the glass transition temperature of the polymer component of the core particle. I have something to do. The difference in glass transition temperature between the polymer component of the core particles and the polymer composed of the polymerizable monomer for shell is usually 10 ° C. or higher, preferably 20 ° C. or higher, more preferably 30 ° C. or higher. I want to adjust it.

When the polymerizable monomer for shell is subjected to suspension polymerization in the presence of core particles, it is preferable to carry out suspension polymerization after forming droplets smaller than the number average particle diameter of the core particles. When the particle size of the droplets of the polymerizable monomer for shells increases, the storage stability tends to decrease. To make the shell polymerizable monomer into small droplets, a mixture of the shell polymerizable monomer and an aqueous dispersion medium, for example, using an ultrasonic emulsifier,
Performs fine dispersion processing. The aqueous dispersion thus obtained is preferably added to the aqueous dispersion medium containing the core particles. The polymerizable monomer for shell is not particularly limited by the solubility in water at 20 ° C., but when the polymerizable monomer for shell having a solubility in water at 20 ° C. of 0.1% by weight or more is used, the solubility in water Since the high monomer easily moves to the surface of the core particle quickly, it is easy to obtain a polymerized toner having good storage stability.

On the other hand, the solubility in water at 20 ° C. is 0.1.
When the polymerizable monomer for shell is used in an amount of less than 5% by weight, the migration to the core particles is slowed down, so it is preferable to add the monomer to the reaction system in the form of fine droplets for polymerization. When a polymerizable monomer for shell having a solubility in water at 20 ° C. of less than 0.1% by weight is used, if an organic solvent having a solubility in water at 20 ° C. of 5% by weight or more is added to the reaction system, the polymerizable property for shell is increased. The monomer quickly moves to the core particles, and it becomes easy to obtain a polymerized toner having good storage stability.

Solubility in water at 20 ° C. is 0.1% by weight
Examples of the shell monomer less than styrene include styrene, butyl acrylate, 2-ethylhexyl acrylate, ethylene and propylene. As the shell monomer having a solubility in water at 20 ° C. of 0.1% by weight or more,
(Meth) acrylic acid esters such as methyl methacrylate and methyl acrylate; amides such as acrylamide and methacrylamide; vinyl cyanide compounds such as acrylonitrile and methacrylonitrile; nitrogen-containing vinyl compounds such as 4-vinylpyridine; vinyl acetate, acrolein, etc. Is mentioned.

Solubility in water at 20 ° C. is 0.1% by weight
Organic solvents that are preferably used when using the following shell monomers include lower alcohols such as methanol, ethanol, isopropyl alcohol, n-propyl alcohol, and butyl alcohol; ketones such as acetone and methyl ethyl ketone; tetrahydrofuran; Examples thereof include cyclic ethers such as dioxane; ethers such as dimethyl ether and diethyl ether; amides such as dimethylformaldehyde.

The organic solvent has a solubility of the shell polymerizable monomer in the dispersion medium (total amount of water and organic solvent) of 0.
An amount of 1% by weight or more is added. Although the amount of the organic solvent used varies depending on the type of the organic solvent and the type and amount of the polymerizable monomer for shell, it is usually 0.1 to 50 parts by weight, preferably 0 to 100 parts by weight of the aqueous dispersion medium. .1 to 4
The amount is 0 parts by weight, more preferably 0.1 to 30 parts by weight.
The order of adding the organic solvent and the polymerizable monomer for the shell to the reaction system is not particularly limited, but promotes the migration of the polymerizable monomer for the shell to the core particles to obtain a polymer toner having good storage stability. In order to make it easier, it is preferable to add the organic solvent to the reaction system first, and then add the shell polymerizable monomer.

Solubility in water at 20 ° C. is 0.1% by weight
When a monomer of less than 0.1% by weight and a monomer of 0.1% by weight or more are used in combination, first, a monomer having a solubility in water at 20 ° C. of 0.1% by weight or more is added and polymerized. , Solubility in water at 20 ° C after adding organic solvent is 0.1% by weight
It is preferable to add less than the following monomers and polymerize. According to this addition method, in order to adjust the fixing temperature of the polymerized toner, the Tg of the polymer obtained from the polymerizable monomer for the shell which is polymerized in the presence of the core particles and the addition amount of the monomer are appropriately adjusted. Can be controlled.

The shell polymerizable monomer is preferably used by mixing with a charge control agent. The charge control agent is used to improve the chargeability of the polymerized toner. As the charge control agent, various positively or negatively charged charge control agents can be used. Specific examples of the charge control agent include Nigrosine N01 (manufactured by Orient Chemical Co., Ltd.) and Nigrosine E.
X (manufactured by Orient Chemical Company), Spiroblack TRH (manufactured by Hodogaya Chemical Company), T-77 (manufactured by Hodogaya Chemical Company), Bontron S-34 (manufactured by Orient Chemical Company), Bontron E-84 (manufactured by Orient Chemical Company), etc. Can be mentioned. The charge control agent is usually 0.01 to 10 parts by weight, preferably 0.03, relative to 100 parts by weight of the monomer composition.
It is used in a proportion of up to 5 parts by weight.

The suspension polymerization of the shell polymerizable monomer in the presence of the core particles is carried out by adding the shell polymerizable monomer to the reaction system of the polymerization reaction carried out to obtain the core particles. And a method of continuously polymerizing, or charging the core particles obtained in another reaction system, adding a shell polymerizable monomer to this, a method of intermittently polymerizing. it can. The polymerizable monomer for shell, in the reaction system,
It can be added all at once, or can be added continuously or intermittently using a pump such as a blanker pump.

When the polymerizable monomer for shell is added, it is preferable to add a water-soluble radical initiator in order to easily obtain a polymer toner having a core / shell structure. When the water-soluble radical initiator is added during the addition of the shell polymerizable monomer, the water-soluble radical initiator enters near the outer surface of the core particle to which the shell polymerizable monomer has migrated, and the core particle surface It is considered that the polymer layer (shell) can be easily formed in the above. As water-soluble radical initiators, persulfates such as potassium persulfate and ammonium persulfate; 4,4-azobis (4-cyanovaleric acid), 2,2-azobis (2-
Amidinopropane) dihydrochloride, 2,2-azobis-2-
Methyl-N-1,1-bis (hydroxymethyl) -2-
Azo initiators such as hydroxyethylpropioamide;
A combination of an oil-soluble initiator such as cumene peroxide and a redox catalyst; and the like. The amount of the water-soluble radical initiator used is usually 0.001 based on the aqueous medium.
~ 1% by weight.

In the polymerized toner of the present invention, the weight ratio of the polymerizable monomer for the core and the polymerizable monomer for the shell is usually 40/60 to 99.9 / 0.1, preferably 60/60.
40-99.7 / 0.3, more preferably 90 / 10-
It is 99.5 / 0.5. If the proportion of the polymerizable monomer for the shell is too small, the effect of improving the storability is small, and conversely, if it is too large, the effect of reducing the fixing temperature and improving the OHP permeability is small. The volume average particle diameter of the polymerized toner of the present invention is usually 0.5 to 20 μm, preferably 3 to 15 μm.
In addition, the fine spherical particles have a sharp particle size distribution (volume average particle size / number average particle size) of usually 1.6 or less, preferably 1.5 or less.

The polymerized toner of the present invention can be used as a developer as it is, but it may be used as a developer by adding various additives (external additives) such as a fluidizing agent. The additive is usually attached to the surface of the polymerized toner. As the additive, various inorganic particles and organic particles can be mentioned. Among these, silica particles and titanium oxide particles are preferable, and silica particles subjected to a hydrophobic treatment are particularly preferable. To attach the additive to the surface of the polymerized toner, usually,
The additive and the polymerized toner are charged into a mixer such as a Henschel mixer and mixed by stirring. These additives serve to improve the fluidity of the polymerized toner. Further, these additives act as an abrasive for the polymerized toner and prevent the occurrence of the toner filming phenomenon on the photoconductor.

When the polymerized toner of the present invention is used, the fixing temperature can be reduced to a low temperature of 60 to 180 ° C., preferably 80 to 150 ° C., and further, it does not aggregate during storage and is excellent in storability. . The image forming apparatus to which the polymerized toner of the present invention is applied is a photoconductor, a means for charging the surface of the photoconductor,
A means for forming an electrostatic latent image on the surface of the photoreceptor, a means for containing toner (developer), a means for supplying toner to develop the electrostatic latent image on the surface of the photoreceptor to form a toner image, and And a means for transferring the toner image from the surface of the photoreceptor to the transfer material. FIG. 1 shows a specific example of such an image forming apparatus.

As shown in FIG. 1, in the image forming apparatus, a photosensitive drum 1 as a photosensitive member is mounted rotatably in the direction of arrow A. The photosensitive drum 1 is a conductive support drum body provided with a photoconductive layer on the outer peripheral surface thereof. The photoconductive layer is composed of, for example, an organic photoconductor, a selenium photoconductor, a zinc oxide photoconductor, an amorphous silicon photoconductor, or the like. Around the photosensitive drum 1, along the circumferential direction thereof, a charging roll 2 as a charging unit, a laser light irradiation device 3 as a latent image forming unit, a developing roll 4 as a developing unit, and a transfer roll 10 as a transferring unit. , And a cleaning device (not shown) is arranged as necessary.

The charging roll 2 is for uniformly charging the surface of the photosensitive drum 1 positively or negatively. A voltage is applied to the charging roll 2 and the charging roll 2
Is brought into contact with the surface of the photosensitive drum 1 to charge the surface of the photosensitive drum 1. The charging roll 2 can be replaced with a charging unit that uses corona discharge.
The laser light irradiation device 3 irradiates the surface of the photosensitive drum 1 with light corresponding to an image signal, irradiates the uniformly charged surface of the photosensitive drum 1 with light in a predetermined pattern, and the light is irradiated. Forming an electrostatic latent image on the part (in the case of reversal development),
Alternatively, it is for forming an electrostatic latent image on a portion not irradiated with light (in the case of regular development). As another latent image forming means, a means including an LED array and an optical system can be mentioned.

The developing roller 4 is for adhering toner to the electrostatic latent image on the photosensitive drum 1. In the reversal development, the toner is attached only to the light irradiation portion, and in the regular development, the light non-irradiation portion. So that the toner adheres only to
A bias voltage is applied between the developing roll 4 and the photosensitive drum 1. In the casing 9 in which the toner 7 is stored,
A developing roll 4 and a supply roll 6 are provided. The developing roll 4 is disposed in close proximity to the photosensitive drum 1 so as to partially contact the photosensitive drum 1, and is rotated in the direction B opposite to the photosensitive drum 1. The supply roll 6 contacts the developing roll 4, rotates in the same direction C as the developing roll 4, and supplies the toner to the outer periphery of the developing roll 4. Casing 9
Inside, a stirring means (stirring blade) 8 for stirring the toner
Is installed.

On the periphery of the developing roll 4, a developing roll blade 5 as a layer thickness regulating means is arranged at a position between the contact point with the supply roll 6 and the contact point with the photosensitive drum 1. The blade 5 is made of conductive rubber or stainless steel, and a voltage of | 200V | to | 600V | is applied to inject charges into the toner. Therefore, the electrical resistivity of the blade 5 is 6 of 10
The power is preferably Ωcm or less.

The casing 9 of the image forming apparatus contains the polymerized toner 7 of the present invention. The polymerized toner 7 may contain an additive such as a fluidizing agent. The polymerized toner of the present invention has a core-shell type structure, and since the shell of the surface layer is formed of a polymer having a relatively high glass transition temperature, it has low surface tackiness and a casing. 9 is suppressed from agglomerating during storage. Further, since the polymerized toner of the present invention has a relatively sharp particle size distribution, when the toner layer is formed on the developing roll 4, it can be formed into a substantially single layer by the layer thickness regulating means 5. Thereby, the reproducibility of the image becomes good.

The transfer roll 10 is for transferring the toner image on the surface of the photosensitive drum 1 formed by the developing roll 4 onto the transfer material 11. The transfer material 11 is paper,
A resin sheet such as an OHP sheet can be used. In addition to the transfer roll 10, the transfer means may be a corona discharge device, a transfer belt, or the like. The toner image transferred onto the transfer material 11 is fixed onto the transfer material by the fixing means. The fixing unit usually comprises a heating unit and a pressure bonding unit. More specifically, the fixing unit is usually composed of a combination of a heating roll (fixing roll) 12 and a pressure roll 13. Transfer material 11 on which the toner image is transferred
Is passed between the heating roll 12 and the pressure roll 13 to melt the toner, and at the same time, the toner is pressed and fixed onto the transfer material 11.

In the image forming apparatus of the present invention, since the polymerized toner of the present invention is used as the toner, even if the heating temperature by the heating means is low, the toner is easily melted and the toner is smoothed by pressing lightly by the pressure bonding means. Since it is in such a state that it is fixed on the surface of the transfer material, high speed printing or copying is possible. Further, the toner image fixed on the OHP sheet has excellent OHP transparency. The cleaning device is for cleaning the transfer residual toner remaining on the surface of the photosensitive drum 1, and is composed of, for example, a cleaning blade. It should be noted that this cleaning device does not necessarily need to be installed when a method of performing cleaning simultaneously with development by the developing roll 4 is adopted.
In the image forming method of the present invention, there is provided an image forming method including a step of attaching a toner to a surface of a photoreceptor on which an electrostatic latent image is formed to form a visible image, and then transferring the visible image to a transfer material. The polymerized toner of the present invention is used as the toner.

[0074]

EXAMPLES The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. Parts and% are based on weight unless otherwise specified.

The methods for measuring the physical properties in Examples and Comparative Examples are as follows. (1) Particle size Particle volume average particle size (dv) and particle size distribution, that is, the ratio of volume average particle size to number average particle size (dp) (dv / dp)
Was measured with a Coulter counter (manufactured by Coulter). As measured by a Coulter counter, aperture diameter: 100 μm, medium: Isoton II, concentration: 15
%, The number of measured particles: 50,000. The thickness of the shell was calculated from the volume average particle diameter of the core particles and the amount of the polymerizable monomer for the shell used. (2) Volume resistivity of toner The volume resistivity of toner is measured by a dielectric loss measuring device (trade name: T
RS-10 type, manufactured by Ando Electric Co., Ltd.) was used, and the temperature was 30 ° C. and the frequency was 1 kHz.

(3) Fixing temperature of toner By modifying a commercially available non-magnetic one-component developing system printer,
The temperature of the fixing roll section can be changed. The image of the toner was evaluated with this modified printer. Fixing rate 80
The temperature of% was evaluated as the fixing temperature. The fixing test was performed by changing the temperature of the fixing roll of the printer, measuring the fixing ratio at each temperature, and determining the relationship between the temperature and the fixing ratio. The fixing ratio was calculated from the ratio of the image density before and after the peeling operation of the adhesive tape after the adhesive tape was attached to the black solid area on the test paper printed by the modified printer, the adhesive tape was pressed with a constant pressure to be adhered. When the image density before peeling the adhesive tape is before ID and the image density after peeling the adhesive tape is after ID, the fixing rate is obtained from the following equation. Fixing rate (%) = (after ID / before ID) × 100 Here, the black solid area is an area in which toner is controlled to adhere to all dots inside the area. Adhesive tape peeling operation means sticking an adhesive tape (Sumitomo 3M Scotch Mending Tape 810-3-18) on the measurement part for test paper, pressing it with a constant pressure to adhere it, and then applying it to the paper at a constant speed. It is a series of operations for peeling the adhesive tape along the direction. Image density is MacB
It was measured using a reflection type image densitometer manufactured by eth company.

(4) Storability of toner To evaluate the storability, the toner sample is put in a closed container and
After sealing, it was immersed in a constant temperature water bath whose temperature was controlled at 50 ° C., taken out after a lapse of a certain time, and weighed the aggregated toner. The sample taken out of the container is transferred onto a 42-mesh sieve without breaking the structure as much as possible, and a powder measuring machine (manufactured by Hosokawa Micron Co., Ltd.)
Set the vibration intensity to 4.5 with REOSTAT of 3
After vibrating for 0 seconds, the weight of the toner remaining on the sieve was measured and used as the weight of the aggregated toner. From the weight of the aggregated toner and the weight of the sample, the aggregation rate of the toner (% by weight)
Was calculated. The storability of the toner was evaluated according to the following four grades. ⊚: Aggregation rate is less than 5% by weight, ◯: Aggregation rate is 5% by weight or more and less than 10% by weight, Δ: Aggregation rate is 10% by weight or more and less than 50% by weight, X: Aggregation rate is 50% by weight or more. (5) OHP transparency The temperature of the fixing roll of the above modified printer is set to 170
The temperature was set to 0 ° C., printing was performed using a commercially available OHP (Transbearency) manufactured by Uchida Yoko Co., Ltd., and the OHP transparency of the toner was evaluated. Whether or not the print was transmitted through the OHP sheet was visually observed, and the transmission or non-transmission was evaluated.

Example 1 Core polymerizable monomer consisting of 70 parts of styrene and 30 parts of n-butyl acrylate (calculation Tg = 35 ° C. of copolymer obtained), carbon black (trade name, manufactured by Degussa) Printex 150T) 5
Part, charge control agent (Hodogaya Chemical Co., Ltd., trade name Spiron Black TRH) 1 part, divinylbenzene 0.3 part, polymethacrylate ester macromonomer (Toa Gosei Chemical Co., Ltd., AA6, Tg = 94 ° C.) 0 0.5 parts and 2 parts of t-butylperoxy-2-ethylhexanoate were stirred and mixed at a rotation speed of 6000 rpm by a homomixer (TK type, manufactured by Tokushu Kika Co., Ltd.) capable of mixing with high shearing force. And uniformly dispersed to obtain a mixed solution for core. On the other hand, methyl methacrylate (calculation Tg of the obtained polymer Tg = 105 ° C.)
5 parts of water, 100 parts of water, and 0.01 part of a charge control agent (Bontron E-84 manufactured by Orient Chemical Co., Ltd.) were finely dispersed by an ultrasonic emulsifying machine to obtain an aqueous dispersion of a polymerizable monomer for shell. Got The particle size of the droplets of the polymerizable monomer for shell was 3% in the obtained droplet in a 1% aqueous solution of sodium hexametaphosphate.
%, And when measured with a Microtrac particle size distribution analyzer, D ₉₀ was 1.6 μm.

On the other hand, in an aqueous solution prepared by dissolving 9.8 parts of magnesium chloride (water-soluble polyvalent metal salt) in 250 parts of ion exchanged water, 6.9 parts of sodium hydroxide (alkali metal hydroxide) in 50 parts of ion exchanged water. An aqueous solution in which was dissolved was gradually added under stirring to prepare a magnesium hydroxide colloid (colloid of sparingly water-soluble metal hydroxide) dispersion. When the particle size distribution of the produced colloid was measured with a Microtrac particle size distribution measuring device (manufactured by Nikkiso Co., Ltd.), the particle size was D
₅₀ (cumulative value of 50% of number particle size distribution) is 0.38 μm,
D ₉₀ (90% cumulative value of number particle size distribution) was 0.82 μm. The measurement by this Microtrac particle size distribution measuring device was carried out under the conditions of measurement range = 0.12 to 704 μm, measurement time = 30 seconds, and medium = ion-exchanged water.

The magnesium hydroxide colloidal dispersion obtained above was charged with the mixed liquid containing the polymerizable monomer for core, and the mixture was mixed with a TK homomixer at 8000 rpm.
The droplets were granulated by high-shear stirring at a rotation speed of. The aqueous dispersion containing the granulated monomer mixture was placed in a reactor equipped with a stirring blade, the polymerization reaction was started at 65 ° C., and when the polymerization conversion rate reached almost 100%, the above-mentioned preparation was performed. Aqueous dispersion of polymerizable monomer for shell and 1 part of 1% aqueous solution of potassium persulfate were added, the reaction was continued for 5 hours, then the reaction was stopped, and polymer particles of core-shell type structure were included. An aqueous dispersion was obtained. Immediately before adding the polymerizable monomer for shell, the volume average particle diameter (d
v) was 5.70 μm, and the volume average particle diameter (dv) / number average particle diameter (dp) was 1.32. The rl / rs of the obtained polymer particles was 1.12, and the toluene insoluble content was 3%.

While stirring the aqueous dispersion of the polymer particles obtained above, the system pH was adjusted to 4 or less with sulfuric acid to perform acid washing (25 ° C., 10 minutes), and water was separated by filtration. Then, 500 parts of ion-exchanged water was added to re-slurry and washed with water. After that, dehydration and washing with water are repeated several times to separate the solid content by filtration, followed by drying at 50 ° C. for one day in a dryer to obtain polymer particles (polymerized toner).
Got To 100 parts of the core / shell type polymerized toner obtained above, 0.3 part of hydrophobized colloidal silica (trade name: R-972, manufactured by Nippon Aerosil Co., Ltd.) was added and mixed using a Henschel mixer. To prepare a non-magnetic one-component developer (sometimes referred to simply as a developer or a toner). When the volume resistivity of the developer thus obtained was measured, it was 11.25 log Ω · c.
It was m. When the fixing temperature was measured using the developer obtained as described above, it was 130 ° C. The storability of this developer was very good (evaluation = ⊚). The results are shown in Table 1. In other image evaluations, an image having a high image density, no fog or unevenness, and an extremely good resolution was obtained.

Example 2 A polymerized toner and a developer were obtained in the same manner as in Example 1, except that the amount of macromonomer was changed to 3 parts. The results are shown in Table 1. In the image evaluation, an image having a high image density and no fog or unevenness and an extremely good resolution was obtained.

Example 3 In Example 1, except that the acrylate macromonomer (AA2, manufactured by Toagosei Chemical Industry Co., Ltd., Tg = about 90 ° C.) was used as the macromonomer.
Polymerized toners and developers were obtained in the same manner as in Example 1. The evaluation results are shown in Table 1.

Example 4 The same as Example 1 except that 5 parts of methyl methacrylate was changed to 1.8 parts of methyl methacrylate and 0.2 parts of butyl acrylate as the polymerizable monomer for shell in Example 1. To obtain a polymerized toner and a developer. The evaluation results are shown in Table 1.

Example 5 In Example 1, 2 parts of styrene was used instead of 5 parts of methyl methacrylate used as the polymerizable monomer for the shell, and immediately before the addition of the polymerizable monomer for the shell. A polymerized toner and a developer were obtained in the same manner as in Example 1 except that 20 parts of methanol was added. The evaluation results are shown in Table 1.

[0086]

[Table 1]

Example 6 In Example 1, 2,2-azobisisobutyronitrile was used in place of t-butylperoxy-2-ethylhexanoate used in the core mixture, and A polymerized toner and a developer were obtained in the same manner as in Example 1 except that the reaction temperature was 90 ° C. The evaluation results are shown in Table 2. When fixing was performed using this developer, some odor was generated.

[Example 7] Polymerization was carried out in the same manner as in Example 1 except that the polymerizable monomer for shell was added in Example 1 without the ultrasonic emulsifier treatment. Toner and developer were obtained. The evaluation results are shown in Table 2.

[Example 8] A polymerized toner and a developer were obtained in the same manner as in Example 1 except that butyl acrylate used as the polymerizable monomer for core was changed to 2-ethylhexyl acrylate. It was The evaluation results are shown in Table 2.

[Comparative Example 1] In Example 1, the amount of the macromonomer used was 0 part (not used), and
Methyl methacrylate 5 used as a polymerizable monomer for shells
Polymerized toner and developer were obtained in the same manner as in Example 1 except that 12 parts of methyl methacrylate was used. The evaluation results are shown in Table 2.

[Comparative Example 2] In Example 1, the polymerizable monomer for the shell was not added, Aerosil 200 (manufactured by Nippon Aerosil Co., Ltd.) was used in place of the magnesium hydroxide colloidal dispersion, and acid washing was carried out. A polymerized toner and a developer were obtained in the same manner as in Example 1 except that alkali washing with an aqueous solution of caustic soda was performed instead of. The evaluation results are shown in Table 2.

[0092]

[Table 2]

Example 9 Polymerized toner and developing were carried out in the same manner as in Example 1 except that 5 parts of phthalocyanine blue (GNX manufactured by Sumitomo Chemical Co., Ltd.) was used instead of 5 parts of carbon black. I got an agent. The evaluation results are shown in Table 3.

[Comparative Example 3] In Example 9, the amount of the macromonomer used was 0 part (not used), and
A polymerized toner and a developer were obtained in the same manner as in Example 9 except that 5 parts of methyl methacrylate used as the polymerizable monomer for shell was changed to 12 parts of methyl methacrylate. The evaluation results are shown in Table 3.

[Comparative Example 4] In Example 9, the amount of the macromonomer used was 0 part (not used), and 70 parts of styrene and 30 parts of n-butyl acrylate used as the polymerizable monomer for the core were used. Change to 85 parts and 15 parts, respectively, without adding the polymerizable monomer for shell, use Aerosil 100 (manufactured by Nippon Aerosil Co., Ltd.) instead of the magnesium hydroxide colloidal dispersion, and use alkali instead of acid washing. A polymerized toner and a developer were obtained in the same manner as in Example 9 except that washing was performed. The evaluation results are shown in Table 3.

[0096]

[Table 3]

[0097]

According to the present invention, there is provided a polymerized toner having a low fixing temperature and uniform melting property, and excellent storage stability, and a method for producing the same. When the polymerized toner of the present invention is used, it is possible to speed up copying and printing, achieve full color, and save energy. Further, the polymerized toner of the present invention is
When printed on a sheet and fixed, it shows excellent transparency. According to the present invention, there are provided an image forming method using a polymerized toner having such excellent properties, and an image forming apparatus containing the polymerized toner.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an aspect of an image forming apparatus of the present invention.

[Explanation of symbols] 1: Photosensitive drum 2: Charging roll 3: Laser light irradiation device 4: Development roll 5: Blade 6: Supply roll 7: Polymerized toner 8: Stirrer 9: Casing 10: Transfer roll 11: Transfer material 12: heating roll 13: Pressure roll

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Jun Sakai 1-2-1, Yokou, Kawasaki-ku, Kawasaki-shi, Kanagawa Inside Zeon Corporation, R & D Center (72) Takahiro Takasaki Yakou, Kawasaki-ku, Kawasaki-shi, Kanagawa 1-2-1 ZEON Corporation General Development Center (72) Inventor Noboru Yanagita 1-2-1 Yokou, Kawasaki-ku, Kawasaki-shi, Kanagawa Japan ZEON Corporation Development Center (56) References Special Kaihei 5-188637 (JP, A) JP 7-248644 (JP, A) JP 3-136065 (JP, A) JP 6-332257 (JP, A) JP 6-317925 ( JP, A) JP 5-181301 (JP, A) JP 8-305193 (JP, A) JP 8-314186 (JP, A) JP 59-116757 (JP, A) JP Flat 5-29762 2 (JP, A) JP-A-1-309070 (JP, A) JP-A-3-197971 (JP, A) JP-A-3-39971 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03G 9/08

Claims (4)

(57) [Claims] 1. In an aqueous dispersion medium containing a dispersant,
Polymer having a colorant and a glass transition temperature of 70 ° C or less
Polymerizable monomer containing core polymerizable monomer capable of forming
The composition was obtained by suspension polymerization in the presence of macromonomer.
The volume average particle diameter (dv) is 0.5 to 20 μm, and the ratio (dv) of the volume average particle diameter (dv) to the number average particle diameter (dp).
/ Dp) is 1.7 or less, and the core particles composed of colored polymer particles suspend the polymerizable monomer for shell in the presence of the core particles.
Polymer component constituting the core particles obtained by suspension polymerization
Core having a glass transition temperature higher than the glass transition temperature of, a shell formed of a polymer layer having an average film thickness of 0.005 to 0.05 μm , and having a toluene insoluble content of 50% or less. Suspension polymerization toner of shell type structure. 2. (1) A polymerizable monomer containing at least a colorant and a polymerizable monomer for core capable of forming a polymer having a glass transition temperature of 70 ° C. or lower in an aqueous dispersion medium containing a dispersant. The monomer composition is suspension-polymerized in the presence of a macromonomer to obtain a volume average particle diameter (dv) of 0.5 to 20 μm, and a volume average particle diameter (dv) and a number average particle diameter (dp). Ratio (dv
/ Dp) is 1.7 or less, and a core particle composed of colored polymer particles is prepared, and then (2) in the presence of the core particle, higher than the glass transition temperature of the polymer component constituting the core particle. A flat polymer which coats the core particles by suspension polymerization of a shell polymerizable monomer capable of forming a polymer having a glass transition temperature.
A method for producing a suspension-polymerized toner having a core-shell structure, in which a toluene-insoluble matter forming a shell composed of a polymer layer having a uniform thickness of 0.005 to 0.05 μm is 50% or less. 3. An image forming method including a step of attaching a toner to a surface of a photoconductor on which an electrostatic latent image is formed to form a visible image, and then transferring the visible image onto a transfer material. In an aqueous dispersion medium containing a dispersant, at least
Forms a polymer with a colorant and glass transition temperature below 70 ° C
Polymerizable monomer composition containing the obtained polymerizable monomer for core
Obtained by suspension polymerization in the presence of a macromonomer has a volume average particle diameter (dv) of 0.5 to 20 μm, a volume average particle diameter (dv) and a number average particle diameter (dp). ) And (dv / d
A core particle composed of colored polymer particles having a p) of 1.7 or less has a polymerizable monomer for shell suspended in the presence of the core particle.
Of the polymer component constituting the core particles obtained by polymerization
A core / shell having a glass transition temperature higher than the glass transition temperature, a shell made of a polymer layer having an average film thickness of 0.005 to 0.05 μm , and having a toluene insoluble content of 50% or less. An image forming method comprising using a suspension polymerization toner having a mold structure. 4. A photoreceptor, means for charging the surface of the photoreceptor,
A means for forming an electrostatic latent image on the surface of the photoconductor, a means for containing toner, a means for supplying the toner to develop the electrostatic latent image on the surface of the photoconductor to form a toner image, and a method for exposing the toner image to light. In an image forming apparatus including means for transferring from the body surface to a transfer material, the means for containing the toner is water containing a dispersant.
In the system dispersion medium, at least the colorant and glass transition temperature
A polymerizable monomer for core capable of forming a polymer at 70 ° C. or lower
In the presence of macromonomer.
The volume average particle size (dv) obtained by suspension polymerization in
Core particles composed of colored polymer particles having a ratio (dv / dp) of the volume average particle diameter (dv) to the number average particle diameter (dp) of 1.7 or less in the presence of the core particles. Che
Core particles obtained by suspension polymerization of a polymerizable monomer for polymer
Above the glass transition temperature of the polymer components that make up
Has a transition temperature and an average film thickness of 0.005 to 0.05 μm
The image forming apparatus is characterized by containing a suspension-polymerized toner having a core-shell type structure, which is covered with a shell made of the polymer layer, and has a toluene insoluble content of 50% or less.