JP3203451B2 - Toner for developing electrostatic images - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner used in a method for visualizing a latent electrostatic image.

[0002]

2. Description of the Related Art In order to visualize an electric or magnetic latent image or the like on a recording medium, it is possible to adsorb electroconductive or magnetically sensitive fine particles called toner to the latent image. There is an image forming method for forming a visual image.

[0003] As a representative example of the electrophotographic method, many methods are known as described in, for example, US Patent No. 2,297,691. In this electrophotography, generally, a photoconductive substance is used to form an electric latent image on a photoreceptor by various means, and then the latent image is developed using toner to form a toner image. Then, if necessary, the toner image is transferred to a transfer material such as paper, and then the toner image is fixed to the transfer material using heat, pressure, solvent vapor, or the like, thereby obtaining a copy. At present, a fixing method using heat has become mainstream in terms of fixing strength of a copy, easiness of handling of a transfer, and work comfort. As a heat fixing method, there is a method using radiant heat such as a heat chamber method, but a so-called heat roller fixing method in which a heated roll-shaped heating element is pressed against a toner image to fix the toner image has high thermal efficiency and high-speed compatibility. It is used in most machines because of its high safety. However,
Even though the efficiency is high, the energy used for heat melting occupies a considerable part in the copier,
Further, it is difficult to avoid a so-called offset phenomenon in which the toner adheres to the heat roll due to direct contact with the melted toner image and contaminates the subsequent image, and a so-called winding phenomenon in which the fixing object is wrapped around the heat roll. There is.

In recent years, there has been a demand for high-speed copying and high-quality electrophotography.

[0005] In general, a toner is produced by melt-mixing a coloring agent such as a dye or pigment and an additive such as a charge control agent into a thermoplastic resin and uniformly dispersing the same, and then using a pulverizer or a classifier. A method for producing a toner having a desired particle size is known.

[0006] In these pulverized toners, there is a restriction when a releasing material such as wax is added.
That is, in order to obtain a sufficient level of dispersibility of the releasable substance, it is necessary that the dispersible substance is not dissolved and liquid at the kneading temperature with the resin and the content of the releasable substance is about 5 parts by weight or less. And so on. Due to such restrictions, there is a limit to the fixability of the toner by the pulverization method.

To solve the above problems, a suspension polymerization method toner containing a release agent such as wax has been proposed. In this suspension polymerization method, a polymerizable monomer and a colorant (and, if necessary, a polymerization initiator, a crosslinking agent, a charge control agent, and other additives) are uniformly dissolved or dispersed to form a monomer composition. After that, the monomer composition is dispersed in a continuous phase (for example, an aqueous phase) containing a dispersion stabilizer by using a suitable stirrer, and simultaneously undergoes a polymerization reaction, whereby toner particles having a desired particle size are obtained. What you get.

In this suspension polymerization method, droplets of the monomer composition are formed in a highly polar dispersion medium called water.
A component having a polar group contained in the monomer composition has a so-called pseudo-capsule structure, in which the component having a polar group is easily present in a surface layer portion which is an interface with an aqueous phase, and a non-polar component is not present in the surface layer portion. By utilizing the characteristics of this production method, it is possible to contain a low melting point wax which cannot be used in other pulverization methods.

By incorporating the low-melting-point wax into the toner produced by the polymerization method, it is possible to achieve both the anti-blocking property and the contradictory performance of low-temperature fixing. That is, since the low-melting-point wax is included, the thermal conductivity in the toner is improved by the wax that melts at a low temperature without lowering the anti-blocking performance, and as a result, low-temperature fixing becomes possible. More preferably, since the wax melted at the time of fixing also functions as a release agent, high-temperature offset can be prevented without applying a release agent such as oil to the fixing roller.

However, when a large amount of a low-melting wax is dissolved and dispersed in a monomer composition of a polymerization toner and granulated in an aqueous medium, granulation is more unstable than in a system containing no wax. It was confirmed that the particle size distribution of the toner tended to be broad.

Further, in order to improve the fixability of such a low-melting-point wax, it is required to increase the amount of the wax. In such a case, it is difficult to completely encapsulate the wax, and although the blocking performance is maintained to some extent, the fluidity of the agent is poor. With respect to the fluidity and cohesiveness of the agent, JP-A-56-116042 and JP-A-56-116043 disclose reactive polyester-containing polymerized toners and JP-A-60-238846 discloses a saturated polyester-containing polymerized toner. Has been proposed.

However, in these production methods,
If a large amount of low-melting wax is contained, the compatibility between the wax and the polyester is poor, so that granulation becomes unstable and the particle size distribution becomes broad.

[0013]

SUMMARY OF THE INVENTION The present inventors have previously reported that in suspension polymerization in an aqueous medium, the polymerization starts at the particle interface, where the polar components are concentrated near the interface and the non-polar components are concentrated at the center. Utilizing the method, a polymerized toner containing a large amount of a wax component that cannot be produced by a toner production method relying on ordinary kneading and pulverization was developed, and a toner which can be fixed at a low temperature was obtained.

However, the granulation property and the fluidity of the agent were slightly inferior.

In the suspension polymerization method, in the case of a styrene-acrylic vinyl polymerizable monomer, the amount of the polymerization initiator is 0.5 to 2
When the polymerization temperature is set so as to be 0% by weight and the half-life of the initiator is 0.5 to 30 hours, it is possible to obtain a toner composition which can be generally used as a thermostatic toner.

When the polymerization conversion rate becomes 90% or more with this setting, the toner particles do not coalesce into a rice cake even if stirring is stopped, and when the polymerization conversion rate reaches 97 and 8%, the toner particles are taken out. If dried, the toner can be used without any problem.

However, when a large amount of low-melting wax is contained in the polymerized toner system, a high-quality image can be obtained without any problem under a normal environment. The phenomenon of lowering occurred.

It is an object of the present invention to provide a color toner for developing an electrostatic image, which solves the above-mentioned problems.

[0019]

The object of the present invention is to provide a polymerizable monomer system containing at least a polymerizable monomer, a colorant, a wax, a styrene-butadiene resin and a polyester resin in an aqueous medium. A toner for developing an electrostatic charge image produced by dispersing and carrying out suspension polymerization, wherein wax is contained in an amount of 5 to 30 wt% based on the toner, and the styrene-butadiene resin is contained in an amount of 1 to 50 wt% based on the wax. % And the content of the organic solvent and the polymerizable monomer is 1,000 ppm or less.

Hereinafter, the present invention will be described in detail.

As described above, according to the suspension polymerization method, the low molecular weight component and the nonpolar component in the polymer can be included in the center of the toner particles. On the other hand, in the suspension polymerization method, as the polymerization reaction proceeds, the viscosity of the polymerizable monomer system increases, making it difficult for radical species and polymerizable monomers to move, and unreacted polymerizable monomers remain in the system. Easy to do. In the case of a toner by a normal pulverization method, residual polymerizable monomers can be driven out by the heat applied during the production of a resin for a toner or during melt-kneading, but in the case of a suspension polymerization method toner that directly produces a toner. Since high heat cannot be applied, a large amount of polymerizable monomer remains in the toner as compared with a normal pulverized toner. If the toner produced by this suspension polymerization method is left at high temperature in the absence of water, the unreacted polymerizable monomer will gradually evaporate from the surface, causing low molecular weight components and nonpolar components inside. That is, it is considered that the low-melting-point wax is conveyed and left on the surface portion, thereby deteriorating the developability of the toner. In the toner, a trace amount of a volatile organic solvent component other than the polymerizable monomer is present.
By regulating the content to be less than or equal to 00 ppm, it is possible to obtain a toner which does not deteriorate even when left at a high temperature with a large amount of a low melting point wax included therein.

However, there were problems with the granulation properties and the fluidity of the agent as described above. Obtaining toner with fluidity and sharp particle size of the agent is indispensable for omission of the classification process found in the pulverization method, developability, and high image quality,
The present inventors have conducted intensive studies.

As a result, a styrene-butadiene resin, which is a polymer having properties equivalent to those of a polymer component and a wax component, and a polyester resin in order to find the fluidity of the agent, are dissolved and mixed in a polymerizable monomer. As a result, it was found that a toner having good fluidity and a sharp particle size can be obtained.

As a reason for the effect, it is suggested that the styrene-butadiene resin has an action of alleviating the phase separation from the polymer component in the polymerization process of the wax in the granulation step, but the details are unknown.

The styrene-butadiene resin used in the present invention may be any copolymer, such as a graft copolymer or a block copolymer, but it has a constitution capable of exhibiting the effect of the present invention more effectively. Is preferably a block copolymer.

Further, as a constitution which can effectively exert the effect of the present invention, the copolymerization ratio of styrene and butadiene is 95:
The ratio is preferably 5 to 65:35. Here, if the styrene ratio exceeds 95%, there is no effect on the granulation properties, while if it is less than a few percent, the granulation properties and the toner blocking properties deteriorate. The reason why the effect is reduced by the copolymerization ratio of styrene-butadiene as described above is considered to indicate that the compatibility between the polymer component and the wax component needs to be balanced.

It is considered that the reason why the block copolymer exerts more effect is that a certain proportion of the compatible component segment for each phase is secured.

In the present invention, the amount of the styrene-butadiene resin to be added is preferably 1 to 50% by weight based on the wax. If the styrene-butadiene resin is less than 1% by weight of the wax, no effect on the granulation properties can be obtained, while if it exceeds 50% by weight, the blocking properties and fluidity of the toner deteriorate.

The wax used in the present invention includes paraffin and polyolefin wax.
The effects of the present invention can be more highly exhibited by using paraffin wax. The reason why the paraffin wax is selected is that it has high solubility in the polymerizable monomer. The melting point of the wax is preferably 50 to 90 ° C., and lower temperature fixing can be achieved.

The feature of the present invention resides in that a polyester resin is further contained. However, granulation properties tend to be further deteriorated when used alone, and when used in combination with the above-mentioned styrene-butadiene resin, the fluidity and granulation properties of the agent are reduced. The sex partner is simultaneously satisfied.

The reason for this is that the toner surface layer is formed of polyester, and as a result, the fluidity of the agent is ensured, and the styrene-butadiene copolymer is used to reduce the tendency of the wax to phase-separate in the monomer system due to the addition of the polyester. It is believed that coalescence acts.

The polyester resin used in the present invention is an unsaturated polyester, and is used in an amount of 0.1% with respect to the polymerizable monomer.
Preferably, the content is 10 to 10 wt%. Addition of less than 0.1% by weight of the polymerizable monomer cannot ensure the fluidity of the agent, while addition of more than 10% by weight deteriorates the granulation properties of the wax-containing system.

Further, the polyester of the present invention may have a
mol% etherified diphenol component and 10-40
mol% of a divalent carboxylic acid or a derivative thereof substituted with a C ₆ -C ₁₆ hydrocarbon group,
It is preferable to include at least 20 wt% of a trivalent or higher polycarboxylic acid and / or a polyol or a derivative thereof.

The present inventors have found that this constituent polyester has good toner fluidity, developability, chargeability and environmental stability, but the reason for the effect is not clear.

Examples of the polymerizable monomer constituting the polymerizable monomer system used in the present invention and the toner property imparting agent such as a colorant include the following.

Examples of the polymerizable monomer include styrene monomers such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene and p-ethylstyrene, and methyl acrylate and acrylic. Ethyl acrylate, n-butyl acrylate, isobutyl acrylate, n-propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, etc. Acrylic esters, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate
Examples thereof include methacrylates such as 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, and diethylaminoethyl methacrylate, and monomers such as acrylonitrile, methacrylonitrile, and acrylamide.

These monomers can be used alone or as a mixture. Among the above-mentioned monomers, it is preferable to use styrene or a styrene derivative alone or in combination with another monomer from the viewpoint of the developing characteristics and durability of the toner.

In the present invention, a polymer may be added to the monomer system in addition to the styrene-butadiene resin and the polyester resin. For example, the monomer contains a hydrophilic functional group such as an amino group, a carboxylic acid group, a hydroxyl group, a sulfonic acid group, a glycidyl group, and a nitrile group, which cannot be used because it dissolves in an aqueous suspension to cause emulsion polymerization due to water solubility. When it is desired to introduce the monomer component into the toner, a random copolymer, a block copolymer, or a graft copolymer of these with a vinyl compound such as styrene or ethylene, in the form of a copolymer, or polyamide. It can be used in the form of polycondensates such as polycondensates, polyethers and polyimines. When such a high molecular polymer containing a polar functional group is coexisted in the toner, the above-mentioned wax component is phase-separated, the encapsulation becomes stronger, and the performance of the toner intended in the present invention is improved. desirable. The amount used is preferably 1 to 20 wt%. The average molecular weight of the high molecular polymer containing these polar functional groups is 5,0.
00 or more is preferably used. When the molecular weight is 5,000 or less, especially 4,000 or less, the present polymer tends to concentrate near the surface, so that adverse effects on developability, anti-blocking properties and the like are likely to occur, which is not preferable. Further, if a polymer having a molecular weight different from the molecular weight range of the toner obtained by polymerizing the monomer is dissolved in the monomer and polymerized, a toner having a wide molecular weight distribution and high offset resistance can be obtained. I can do it.

As the colorant used in the present invention, known colorants can be used, and carbon black, iron black, C.I. I.
Direct Red 1, C.I. I. Basic Red 1,
C. I. Modant Red 30, C.I. I. Direct Blue 1, C.I. I. Direct Blue 2, C.I. I. Acid Blue 15, C.I. I. Basic Blue 3, C.I. I.
Basic Blue 5, C.I. I. Modant Blue 7,
C. I. Direct Green 6, C.I. I. Basic Green 4, C.I. I. Dyes such as Basic Green 6, etc., graphite, cadmium yellow, mineral first yellow, navel yellow, naphthol yellow S, Hanza yellow G, permanent yellow NCG, tartrazine lake, molybdenum orange GTR, benzidine orange G, cadmium red 4R, watching red Calcium salt, Brilliant Carmine 3B, Fast Violet B, Methyl Violet Lake, Navy Blue, Cobalt Blue, Alkaline Blue Lake, Victoria Blue Lake, Quinacridone, Rhodamine Lake, Phthalocyanine Blue, Fast Sky Blue, Pigment Green B, Malachite Green Lake, Final Yellow There are pigments such as Green G. In the present invention, in order to obtain a toner using a polymerization method, it is necessary to pay attention to the polymerization inhibitory properties and aqueous phase migration of the colorant, preferably surface modification,
For example, it is better to perform a hydrophobic treatment using a substance having no polymerization inhibition. In particular, dyes and carbon black often have polymerization inhibitory properties, so care must be taken when using them. As a preferable method of surface-treating a dye system, a method of polymerizing a polymerizable monomer in the presence of these dyes in advance is exemplified.

The carbon black may be subjected to a grafting treatment with a substance which reacts with the surface functional group of the carbon black, such as polyorganosiloxane or polyethylene glycol, in addition to the same treatment as the above dye. Other pigments are less strongly inhibited by polymerization than carbon black, but it is better to perform the same treatment in consideration of dispersion into a polymerizable monomer.

A magnetic toner may be obtained by adding a magnetic substance.

The toner according to the present invention may contain a charge control agent for stabilizing the charge characteristics. In this case, a colorless or light-colored charge control agent which does not affect the color tone of the toner is preferred.

The polymerization initiator used in the present invention, which has a half-life of 0.5 to 30 hours during the polymerization reaction, is subjected to the polymerization reaction in an amount of 0.5 to 20% by weight of the polymerizable monomer. In addition, a polymer having a maximum molecular weight of 10,000 to 100,000 can be obtained, and the toner can have desired strength and appropriate melting characteristics. Examples of the polymerization initiator include 2,2′-azobis- (2,4-dimethylvaleronitrile) and 2,2′-
Azo such as azobisisobutyronitrile, 1,1'-azobis (cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, azobisisobutyronitrile -Based or diazo-based polymerization initiator, benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydroperoxide, 2,4-
Peroxide-based polymerization initiators such as dichlorobenzoyl peroxide and lauroyl peroxide are exemplified.

In the present invention, a crosslinking agent may be added, and the preferable addition amount is 0.001 to 15% by weight.

In the toner production method of the present invention, generally, a colorant, a release agent, a plasticizer, a binder, a charge control agent, a cross-linking agent, a magnetic substance, etc. are contained in the above-mentioned toner composition, ie, a polymerizable monomer. Components necessary as a toner and other additives, for example, an organic solvent to be added to reduce the viscosity of the polymer formed by the polymerization reaction, a dispersant and the like are added as appropriate, and a homogenizer,
A monomer system uniformly dissolved or dispersed by a disperser such as a ball mill, a colloid mill, and an ultrasonic disperser is suspended in an aqueous medium containing a dispersion stabilizer. At this time, the particle size of the obtained toner particles becomes sharper by using a high-speed disperser such as a high-speed stirrer or an ultrasonic disperser to make the desired toner particle size at once. As for the timing of the addition of the polymerization initiator, it may be added at the same time as the other additives are added to the polymerizable monomer, or may be mixed immediately before being suspended in the aqueous medium. Immediately after granulation and before initiating the polymerization reaction, a polymerization initiator dissolved in a polymerizable monomer or a solvent can be added.

After the granulation, stirring may be performed using a conventional stirrer to such an extent that the particle state is maintained and the particles are prevented from floating and settling.

In the suspension polymerization method of the present invention, known surfactants and organic / inorganic dispersants can be used as dispersion stabilizers. Among them, inorganic dispersants hardly generate harmful ultrafine powders, and due to their steric hindrance, Since dispersion stability is obtained, even if the reaction temperature is changed, the stability is hardly lost, the washing is easy, and the toner is hardly adversely affected. Examples of such inorganic dispersants include calcium phosphate, magnesium phosphate, aluminum phosphate, polyvalent metal phosphates such as zinc phosphate, calcium carbonate, carbonates such as magnesium carbonate, calcium metasilicate, calcium sulfate, barium sulfate and the like. Examples include inorganic salts, inorganic oxides such as calcium hydroxide, magnesium hydroxide, aluminum hydroxide, silica, bentonite, and alumina.

[0048] These inorganic dispersants are composed of polymerizable monomers 10
It is desirable to use 0.2 to 20 parts by weight alone with respect to 0 parts by weight, but 0.001 to 0.1 parts by weight, since it is difficult to generate ultrafine particles but a little poor at atomizing the toner. May be used in combination.

Examples of the surfactant include sodium dodecylbenzene sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate,
Examples include sodium oleate, sodium laurate, sodium stearate, potassium stearate and the like.

When these inorganic dispersants are used, they may be used as they are, but in order to obtain finer particles, the inorganic dispersant particles can be formed in an aqueous medium. For example, in the case of calcium phosphate, a water-insoluble calcium phosphate can be produced by mixing an aqueous solution of sodium phosphate and an aqueous solution of calcium chloride under high-speed stirring, and more uniform and fine dispersion can be achieved. At this time, a water-soluble sodium chloride salt is simultaneously produced as a by-product, but if the water-soluble salt is present in the aqueous medium, the dissolution of the polymerizable monomer in water is suppressed, and the ultrafine toner due to emulsion polymerization is formed. This is more convenient because it hardly occurs. Since it becomes an obstacle when removing the residual polymerizable monomer at the end of the polymerization reaction, it is better to replace the aqueous medium or to desalinate with an ion exchange resin. The inorganic dispersant can be almost completely removed by dissolving with an acid or alkali after completion of the polymerization.

In the polymerization step, the polymerization temperature is 40
The polymerization is carried out at a temperature of at least 50 ° C., generally from 50 to 90 ° C. When the polymerization is carried out in this temperature range, the release agent and waxes to be sealed inside are precipitated by phase separation, and the encapsulation becomes more complete. In order to consume the remaining polymerizable monomer, the reaction temperature is 90 to 90 at the end of the polymerization reaction.
It is possible to increase to 150 ° C.

Under the above conditions, the conversion rate increases almost linearly up to the polymerization conversion rate of 90%, but the solidification rate of the toner is reduced to 90%.
% Or more, the increase in the degree of polymerization is slowed, and when the polymerization conversion rate is 95% or more, it becomes very slow. The polymerization reaction may proceed as it is, and the amount of the residual polymerizable monomer may be controlled so as to be 1,000 ppm or less, but a known polymerizable monomer consumption promoting means in a suspension polymerization method can be used.

Means employed in the method for producing a polymerized toner of the present invention include, when the polymerization conversion reaches 95% or more, a temperature rise of 20 to 60 ° C., a decrease in viscosity due to heat, and a start of thermal polymerization. In this case, if a polymerization initiator which decomposes at a high temperature is made to coexist in the polymer system, the polymerizable monomer can be effectively consumed.

Further, by stopping the reflux or reducing the pressure, a part of the unreacted polymerizable monomer and / or the organic solvent is distilled off to reduce the residual amount to 1,000 ppm or less. It is preferred in terms of. Instead of holding in water, for example, while cooling the steam to 40-50 ° C,
By exposing the toner particles wetted with water to supersaturated water vapor, the residual amount can be reduced to 1,000 ppm or less while maintaining the same effect as holding the toner particles in water.

In addition, as a method of consuming the polymerizable monomer by increasing the polymerization addition rate, an organic solvent which is a solvent of the toner is put into the polymer system, and a plasticizer is used to such an extent that the blocking resistance of the toner is not deteriorated. There is a method of lowering the viscosity of the polymer system by putting the amount in the polymer system.

As a method for removing the unreacted polymerizable monomer and / or the organic solvent, a high volatility in which the toner binder resin does not dissolve but the polymerizable monomer and / or the organic solvent component dissolves. A method of washing with an organic solvent, a method of washing with an acid or an alkali, a foaming agent or a solvent component that does not dissolve the polymer is put into a polymer system, and a polymerizable monomer inside by making the obtained toner porous, Alternatively, there is a method of increasing the volatilization area of the organic solvent component.However, since it is difficult to select a solvent such as elution of toner components and persistence of the solvent, the polymerizable monomer and / or organic solvent component is volatilized under reduced pressure. How to make it
Most preferred.

Finally, at least 1000 ppm or less, a polymerizable monomer generated at the time of fixing and its reaction residue,
Alternatively, in order to eliminate the off-flavor due to the solvent, the content is more desirably 100 ppm or less.

The polymerization conversion rate was determined by adding a polymerization inhibitor to 1 g of the suspension and dissolving it in 4 ml of THF. The amount of the residual polymerizable monomer and the residual organic solvent was determined using 0.2 g of the toner. What was dissolved in 4 ml of THF was measured by an internal standard method under the following conditions by gas chromatography.

G. C. Conditions Measuring device: Shimadzu GC-15A (with capillary) Carrier: N ₂ , 2 Kg / cm ² 50 ml / min.
split ratio 1:60, linear velocity 30 mm / sec. Column: ULBON HR-1 50m x 0.25m
m Sample amount: 2 μl Labeled substance: toluene Hereinafter, the present invention will be specifically described based on Examples and Comparative Examples.

[0060]

EXAMPLE 1 To 709 g of ion-exchanged water, 451 g of a 0.1 M Na ₃ PO ₄ aqueous solution was added, and after heating to 60 ° C., 1.0 M-
67.7 g of a CaCl ₂ aqueous solution was gradually added to add Ca ₃
An aqueous medium containing (PO ₄ ) ₂ was obtained.

Styrene 170 g n-butyl acrylate 30 g C.I. I. Pigment Blue 15: 3 10 g Styrene-butadiene copolymer 3 g (15 wt% based on wax) [Clearene 730L (manufactured by Denki Kagaku Kogyo), St / Buta = 75/25] Paraffin wax (mp. 75 ° C.) 20 g Di- t-Butylsalicylic acid metal compound 5 g Polyester resin 2 g The above formulation was heated to 60 ° C. and uniformly dispersed and dissolved at 12,000 rpm using a TK homomixer (manufactured by Tokushu Kika Kogyo). To this, a polymerization initiator 2,2'-azobis (2,4-dimethylvaleronitrile) [t1 / 2 = 140
min. at 60 ° C.] 10 g, and dimethyl-2,2 ′
Azobisisobutyrate [t1 / 2 = 1,270 mi
n. at 60 ° C., t1 / 2 = 80 min. at 80 ° C] 1
g was dissolved to prepare a polymerizable monomer system.

The above polymerizable monomer system was charged into the aqueous medium, and the mixture was stirred at 8,000 rpm for 15 minutes using a TK homomixer at 60 ° C. in an N ₂ atmosphere to obtain a suspension droplet having a toner particle size. Granulated. Thereafter, the mixture was reacted at 60 ° C. for 3 hours while stirring with a paddle stirring blade. At this point, the polymerization conversion was 90%. Thereafter, the reflux of the steam was stopped, the liquid temperature was raised to 80 ° C., and stirring was continued for another 10 hours.
After completion of the reaction, the suspension was cooled, and hydrochloric acid was added to add Ca ₃ (P
O ₄ ) ₂ is dissolved, filtered, washed with water and dried to obtain a weight average diameter =
A polymer toner of 8.7 μm was obtained. 45 ° C
A degassing treatment was performed for 12 hours under a reduced pressure of 50 mmHg. At this time, the amount of the polymerizable monomer remaining is 150
ppm.

The particle size distribution of the obtained toner became sharp. Table 2 shows the particle size distribution.

The fluidity of the agent was also good.
The particle size distribution was measured by the following method.

That is, a Coulter Counter TA-II type (manufactured by Coulter Inc.) is used as a measuring device, and an interface (manufactured by Nikkaki) that outputs a number distribution and a volume distribution.
And a CX-1 personal computer (manufactured by Canon Inc.), and the electrolyte was 1% Na using primary sodium chloride.
Prepare a Cl aqueous solution. As a measuring method, a surfactant, preferably an alkylbenzene sulfonate, is used as a dispersant in 100 to 150 ml of the electrolytic aqueous solution in an amount of 0.1 to 5 m.
and 2 to 20 mg of the measurement sample. The electrolytic solution in which the sample was suspended was subjected to a dispersion treatment for about 1 to 3 minutes with an ultrasonic disperser, and by the Coulter counter TA-II,
Using a 100 μm aperture as the aperture, the particle size distribution of particles of 2 to 40 μm was measured based on the number.

0.6 g of hydrophobic silica was externally added to 100 g of the above polymerized toner. Furthermore, this silica external additive 30
g and 570 g of a resin-coated ferrite carrier were mixed to obtain a two-component developer.

Using this developer, a commercial color copier (CLC-500, manufactured by Canon) was modified to produce an image. The development condition was a development contrast of 320 V in an environment of 23 ° C./65%.

An unfixed image on the above copy which was just developed and copied by a modified machine of CLC-500 was used as an external fixing machine (a fixing roller was a fluorine soft roller and a pressure roller was a silicon roller (oil coating). No function)). The obtained fixed image was excellent in fixability without offset. Also,
When this developer was left in an environment of 35 ° C. for one month, the image quality was as good as the initial one.

Comparative Example 1 In Example 1, the same state was maintained after 3 hours of the reaction, and after a total of 8 hours, when the polymerization conversion reached 99% or more, the toner was taken out, and the dispersant was washed and dried. Was performed.
At this point, the amount of the residual polymerizable monomer was 4,300 ppm. When the toner was adjusted for the developer in the same manner as in Example 1, and an image was formed, a good image was obtained as in Example 1. However, styrene odor was emitted from around the fixing device. When this toner was allowed to stand for one month in an environment of 35 ° C., toner tribo was extremely reduced, and an image with much fog was formed.

Examples 2 to 4 and Comparative Examples 2 to 5 Toners having different wax contents and residual polymerizable monomers in Example 1 were produced and evaluated.

Table 1 lists the details. Table 2 shows the particle size distribution in granulation.

[0072]

[Table 1]

[0073]

[Table 2] In terms of granulation properties, emulsion stability, interfacial tension,
And the dispersibility of pigments and the like are greatly involved. In addition, pigment dispersibility is based on additives, resins,
Compatibility of wax and the like is important.

From this viewpoint, the interfacial tension of the system was measured in Example 1 and Comparative Examples 2 and 5, and the results are shown in Table 3. Table 3 also shows the dispersibility of the pigment during granulation. The pigment dispersibility was determined by visual observation using a microscope. Table 3 clearly shows that the pigment dispersibility and the decrease in interfacial tension can be used as a material for determining the granulation properties.

[0075]

[Table 3]

[0076]

According to the present invention, the suspension polymerization toner includes
Because it contains a styrene-butadiene resin and a polyester resin, granulation properties and fluidity of the agent are improved,
A high quality fixed image can be obtained.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tatsuya Nakamura 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Makoto Shinbayashi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon (72) Inventor Kazuyuki Miyano 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) References JP-A-3-80260 (JP, A) JP-A-2-245768 (JP) JP-A-3-155567 (JP, A) JP-A-2-64652 (JP, A) JP-A-5-127424 (JP, A) (58) Fields studied (Int. Cl. ⁷ , DB G03G 9/08-9/097

Claims (4)

(57) [Claims] At least a polymerizable monomer, a coloring agent, a wax, a styrene-butadiene resin and a polyester resin.
The polymerizable monomer system containing, a toner for electrostatic image development prepared by <br/> suspension is dispersed in an aqueous medium, 5～30W wax relative to the toner
t% is contained, the styrene - wherein the butadiene resin is contained 1 to 50 wt% relative to the wax <br/> scan, and the content of the organic solvent and the polymerizable monomer is not more than 1,000ppm Toner for developing an electrostatic image. 2. The polyester resin is an unsaturated polyester, and 0.1 to 1.0% by weight based on a polymerizable monomer.
The toner for developing an electrostatic image according to claim 1, wherein the toner is contained. 3. The styrene-butadiene resin is a block copolymer resin and the ratio of styrene to butadiene is 95: 5 to 65:35.
Or the toner for developing an electrostatic image according to 2. 4. The electrostatic image developing toner according to claim 1, wherein the wax is a paraffin wax and has a melting point of 50 to 90 ° C.