JP3136428B2 - Method for producing toner composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a toner composition including a step of melting and kneading a toner for developing an electrostatic image and a magnetic latent image in electrophotography, electrostatic printing, magnetic recording and the like. About. In particular, the present invention relates to a method for producing a toner composition including a step of melting and kneading a toner for developing an electrostatic image used in a heat fixing method such as heat roller fixing.

[0002]

2. Description of the Related Art Toners for electrophotography are obtained by mixing raw materials such as a binder resin, a release agent, a charge control agent, a magnetic material, a pigment or a dye as a colorant, and additives as necessary with a ball mill, a Henschel mixer or the like. By pre-mixing with a machine, melt-kneading using a kneading device such as a heating roll, kneader, extruder, cooling and solidifying, coarsely pulverizing with a hammer mill, etc., and then classifying the finely pulverized with a jet mill, etc. Manufactured. In the melt-kneading step at this time, it is necessary to uniformly disperse a release agent, a charge control agent, and the like in the binder resin. When poor dispersion occurs, in the subsequent pulverizing and classifying processes, uneven release and release of the release agent component are caused, or the charging characteristics are deteriorated, thereby causing image stains such as fog, photosensitive members, and developer carrying members. Or the surface of the charging member or the like.

[0003] As described above, the melt-kneading step is an important step in toner production. As a kneading apparatus usually used for producing a toner, a twin-screw extruder is used because continuous production is possible.

[0004] In a twin-screw extruder, two rotating shafts called paddles pass through a heating cylinder for maintaining a constant temperature. The raw material is supplied from one end of a heating cylinder, heated, melted, kneaded by rotation of a paddle, and extruded from the other end. In some cases, a pent mouth for the main purpose of deaeration may be installed.

FIG. 2 is a schematic view of a paddle. The cross section of the paddle may be a propeller-shaped one or a triangular-shaped one as shown in the figure, and is set out of phase so that one tip always rotates as if rubbing the other. This structure has a self-cleaning action of sending the kneaded material forward without adhering to the paddle and the cylinder wall. The directions of rotation of the two paddles may be the same or different, but the same direction is common.

[0006] The paddle is roughly composed of two types of parts, one of which is a feed screw portion, and a schematic diagram thereof is shown in FIG. This part is an S spiral screw that has the function of heating the kneaded material and sending it forward.If the viscosity of the kneaded material in the cylinder is high, the shear force due to the friction between the wall of the screw part and the kneaded material It is kneaded, but if it is low, it is hardly kneaded. The other is kneading, where kneading is mainly performed. Here, a combination of a propeller-like block as shown in FIGS. 4 and 5, a pineapple-like block as shown in FIG. 6, a return screw for feeding in the direction opposite to the extrusion, and the like are used. This portion has almost no effect of sending the kneaded material forward, and the kneaded material stays and fills. The kneading is performed in response to the volume change of the compression and the stretching accompanying the rotation of the paddle. If the kneading portion is short or absent, the kneaded material hardly stays and is extruded before the kneaded material is completely melted.

[0007] The setting conditions of the extruder include a heating temperature, a paddle configuration, a paddle rotation speed, a supply amount of raw materials, and the like.

When the kneaded material is in the paddle portion, the shear is suspended, so that the release agent can be maintained in a dispersed state. In addition to being small, the melt viscosity of the release agent becomes extremely small, and reaggregation of the release agent starts. If the time is long, the dispersion particle size of the release agent becomes large, resulting in a situation similar to poor dispersion. Therefore,
In the pulverizing and classifying steps, the release agent component tends to be unevenly distributed and released.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a toner composition which solves the above-mentioned problems.

[0010] That is, an object of the present invention is to provide a method for producing a toner composition in which the dispersibility of the release agent is good and there is no uneven distribution, so that the generation of free release agent during pulverization and classification is small. is there.

[0011]

SUMMARY OF THE INVENTION The present invention relates to a method for producing a toner composition by melt-kneading a raw material mixture containing at least a binder resin, a colorant, and a release agent using an extruder. The extruder is a kneading device that has a material input port and a discharge port, and a paddle is provided in the cylinder in the axial direction. The heating temperature of the discharge port cylinder is the heating temperature of the cylinder at the paddle section on the most discharge side. A method for producing a toner composition, wherein the temperature is 10 ° C. or lower.

FIG. 1 shows a schematic view of an example of a kneading apparatus used in the production method of the present invention, and the present invention will be described in more detail with reference thereto, but the present invention is not limited thereto.

The toner raw material mixture supplied from the supply port 4 is heated by the heating cylinders 1 and 7 to be in a molten state, and is sheared and kneaded at the screw portion, especially at the kneading portion, where the raw material is dispersed. The kneaded material is discharged from the outlet and cooled to become a toner composition.

Conventionally, since the kneaded material of the toner composition has a high melt viscosity, the discharge port heating is set so as to be equal to or higher than the set temperature of the paddle section heating cylinders 1 and 7 so that the kneaded product is discharged from the discharge section. The cylinder 5 is set. However, recently, there has been a change to toner formulations that improve low-temperature fixing, and the melt viscosity tends to be low. When such a toner composition can depend on kneading, the kneaded material enters the outlet cylinder 5 at a high temperature and a low melt viscosity. At this time, the melt viscosity of the release agent is extremely low, and the shear is not suspended.Therefore, the release agent re-aggregates in combination with the low melt viscosity of the kneaded material, and the dispersed particle size increases. I will. As a result, the release agent is unevenly distributed, and a free release agent is generated during pulverization and classification.

According to the present invention, the heating temperature of the discharge port cylinder 5 is set at 10 ° C. lower than the heating temperature of the discharge section paddle cylinder 7.
It is characterized in that it is set at a lower level, so that re-aggregation of the release agent is prevented, and a toner composition with a good dispersion state of the release agent is obtained, and free wax is less generated in pulverization classification. A more preferable set temperature is lower by 20 ° C. or more. It is also preferable that the set temperature is lower than the softening point of the release agent used. Further, when the heating temperature of the discharge port cylinder 5 is lower than 60 ° C., it becomes difficult to discharge and the cylinder is easily clogged. Therefore, the temperature is preferably set to 60 ° C. or higher, and more preferably 70 ° C. or higher.

As in the present invention, by lowering the heating temperature, the kneaded material in the outlet cylinder 5 is supplied with less heat energy from the outside, and becomes closer to an adiabatic state. Further, since the kneaded material is extruded one after another, pressure is applied to the kneaded material in the discharge port cylinder 5. Since the kneaded material makes up for the loss of the free volume with thermal energy, as a result, the temperature of the kneaded material decreases. The decrease in the temperature lowers the melt viscosity of the kneaded material and also lowers the melt viscosity of the release agent, so that it is possible to obtain a toner composition in which reaggregation of the release agent is suppressed. Furthermore, since the cooling rate at the time of cooling can be increased, reagglomeration can be further suppressed. Therefore, uneven release of the release agent can be prevented, and release of the release agent during pulverization and classification can be reduced. As a result, the toner obtained from such a toner composition does not contaminate the photosensitive member, the toner carrying member, and the charging member, does not impair the charge of the toner, and does not deteriorate the developability. There is no cleaning failure.

In the present invention, it is preferable to provide a kneading portion in order to improve the dispersion of the toner raw material, and it is particularly preferable to provide two or more kneading portions. By providing the kneading portion, the toner raw material is retained in the paddle, and the mixture is melt-kneaded while being completely sheared as a melt to obtain a kneaded material having a good dispersion state. Further, by performing the operation of the present invention from this state, a toner composition having a good release agent dispersion can be obtained.

The paddle of the kneading part is shown in FIG.
Any of those having the effect of retaining the kneaded material, such as those having the shapes shown in FIGS. 5 and 6 and return screws, can be used,
They can be used in combination of several kinds.

The release agent used in the present invention has a softening point of 1
The temperature is 60 ° C or lower, preferably 80 ° C to 140 ° C, more preferably 90 ° C to 130 ° C. Also, offset resistance,
From the viewpoint of fixability, the melt viscosity at 140 ° C. is preferably 1,000 cP or less, more preferably 400 cP or less, and particularly preferably 200 cP or less. Specific examples thereof include paraffin wax, micro wax, Fischer-Tropsch wax, montan wax, higher alcohol-based wax, amide wax, higher fatty acid, higher fatty acid ester, ethylene, propylene, butene-1, pentene-1, hexene-1, Heptene-1,
Homopolymers of linear α-olefins such as octene-1, nonene-1 and decene-1, branched α-olefins having a branched terminal, and olefins having different positions of these unsaturated groups Alternatively, a copolymer of these may be used.

Further, a modified wax obtained by subjecting a vinyl-based monomer to block copolymerization, graft modification, or the like may be used.

The amount of the wax added is preferably from 0.5 to 10 parts by weight, more preferably from 1 to 8 parts by weight, per 100 parts by weight of the resin. In addition, 2
More than one type of wax may be added in combination.

The melt viscosity is a value measured using a Brookfield viscometer. The conditions are 140 ° C., a shear rate of 1.32 rpm, and a sample of 10 ml. Softening point is JIS
This is a value measured according to K2207.

As the binder resin used in the toner composition of the present invention, the following binder resins can be used.

For example, homopolymers of styrene such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene and substituted products thereof; styrene-p-chlorostyrene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene Copolymer, styrene-acrylate copolymer, styrene-methacrylate copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-
Styrene such as vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer -Based copolymer; polyvinyl chloride, phenolic resin, natural modified phenolic resin, natural resin modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester resin, polyurethane, polyamide resin, furan resin, epoxy resin , Xylene resin, polyvinyl butyral, terpene resin, coumarone indene resin, petroleum resin and the like can be used. Preferred binder resins include styrene copolymers and polyester resins.

Examples of comonomers for the styrene monomer of the styrene copolymer include acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, and the like.
Such as dodecyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate, acrylonitrile, methacrylonitrile, acrylamide, etc. Monocarboxylic acid having a heavy bond or a substituted product thereof; for example, dicarboxylic acid having a double bond such as maleic acid, butyl maleate, methyl maleate, dimethyl maleate and the like; and substituted products thereof; for example, vinyl chloride, vinyl acetate And vinyl esters such as vinyl benzoate; ethylene-based olefins such as ethylene, propylene and butylene; vinyl ketones such as vinyl methyl ketone and vinyl hexyl ketone; Chirueteru, vinyl ethyl ether, vinyl ethers such as vinyl isobutyl ether; vinyl monomers are used alone or two or more.

The styrene-based polymer or styrene-based copolymer may be crosslinked or a mixed resin.

As the crosslinking agent for the binder resin, a compound having at least two polymerizable double bonds may be used. For example, aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; carboxylic acid esters having two double bonds such as ethylene glycol diacrylate, ethylene glycol dimethacrylate, and 1,3-butadiol dimethacrylate; Divinyl compounds such as divinylaniline, divinyl ether, divinyl sulfide and divinyl sulfone; and 3
Compounds having at least two vinyl groups are used alone or as a mixture.

In the toner composition of the present invention, a charge control agent can be used by blending (internally adding) it to the developer particles.
The charge control agent makes it possible to control the amount of charge optimally according to the development system. In particular, in the present invention, the balance between the particle size distribution and the charge can be further stabilized. Examples of the positive charge controlling agent include denatured products such as nigrosine and fatty acid metal salts; quaternary ammonium salts such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonic acid and tetrabutylammonium tetrafluoroborate, and analogs thereof. Onium salts such as phosphonium salts and the like, lake pigments thereof, triphenylmethane dyes and these lake pigments, (phosphorus tungstic acid, phosphomolybdic acid, phosphotungsten molybdic acid, tannic acid, lauric acid, gallic Acid, ferricyanide, ferrocyanide, etc.) metal salts of higher fatty acids; diorganotin oxides such as dibutyltin oxide, dioctyltin oxide, dicyclohexyltin oxide; dibutyltin borate, dioctyltin borane DOO, diorgano tin borate such as dicyclohexyl tin borate; can be used in combination singly or two or more kinds. Among these, charge control agents such as nigrosine, quaternary ammonium salts, and triphenylmethane pigments are particularly preferably used.

Further, the general formula

[0030]

Embedded image Monomer of a monomer represented by: styrene described above,
Copolymers with polymerizable monomers such as acrylates and methacrylates can be used as positive charge control agents. In this case, these charge control agents also act as (all or part of) the binder resin.

The following substances control the toner to be negatively charged.

For example, organic metal complexes and chelate compounds are effective, and examples thereof include monoazo metal complexes, acetylacetone metal complexes, aromatic hydroxycarboxylic acids, and aromatic dicarboxylic acid-based metal complexes. Other examples include aromatic hydroxycarboxylic acids, aromatic mono- and polycarboxylic acids and their metal salts, anhydrides, esters, and phenol derivatives such as bisphenol.

The above-mentioned charge control agent (having no action as a binder resin) is preferably used in the form of fine particles. In this case, the number average particle size of the charge control agent is
Specifically, it is preferably 4 μm or less (more preferably 3 μm or less).

When added internally to the developer, such a charge control agent is preferably used in an amount of 0.1 to 20 parts by weight (more preferably 0.2 to 10 parts by weight) based on 100 parts by weight of the binder resin. .

Further, the toner composition of the present invention can be used as a magnetic toner by further containing a magnetic material. In this case, the magnetic material can also serve as a colorant. In the present invention, the magnetic material contained in the magnetic toner includes iron oxides such as magnetite, maghemite, and ferrite; metals such as iron, cobalt, and nickel; or aluminum, cobalt, copper, lead, magnesium, and tin of these metals. , Zinc, antimony, beryllium, bismuth,
Cadmium, calcium, manganese, selenium, titanium,
Alloys of metals such as tungsten and vanadium and mixtures thereof can be given.

These ferromagnetic materials preferably have an average particle size of 2 μm or less, preferably about 0.1 to 0.5 μm. The amount contained in the toner is preferably about 20 to 200 parts by weight, particularly preferably 40 to 150 parts by weight, per 100 parts by weight of the resin component.

The magnetic properties when 10 K Oersted is applied are as follows: the coercive force ratio (Hc) is 20 to 300 Oersted, the saturation magnetization (σs) is 50 to 200 emu / g, and the residual magnetization (σ
r) Those having 2 to 20 emu / g are preferred.

As the colorant that can be used in the toner composition of the present invention, any suitable pigment or dye can be used. Examples of the colorant of the toner include pigments such as carbon black, alinine black, acetylene black, naphthol yellow, hansa yellow, rhodamine lake, alizarin lake, bengara, phthalocyanine blue, and indanthrene blue. These are used in an amount necessary and sufficient to maintain the optical density of the fixed image.
0.1 to 20 parts by weight, preferably 0.2 to 0 parts by weight
The addition amount of 10 to 10 parts by weight is good. A dye is further used for the same purpose. For example, there are azo dyes, anthraquinone dyes, xanthene dyes, methine dyes and the like, and 0.1 to 20 parts by weight, preferably 0.3 to 10 parts by weight, per 100 parts by weight of the resin is good.

To prepare a toner composition according to the present invention, a binder resin, a release agent, a metal salt or metal complex, a pigment or dye as a colorant, a magnetic substance, a charge control agent if necessary,
The other additives, etc. are thoroughly mixed by a mixer such as a Henschel mixer or a ball mill, and then melt-kneaded by using a hot kneader using the method of the present invention to release the resin while the resins are mutually compatible. It can be obtained by dispersing or dissolving an agent, a metal compound, a pigment, a dye, and a magnetic substance, and solidifying it by cooling. Thereafter, it can be pulverized and classified to obtain a toner.

Further, if necessary, desired additives are sufficiently mixed by any mixer such as a Henschel mixer to obtain a toner for developing an electrostatic image.

[0041]

The present invention will be described below with reference to specific examples, but the present invention is not limited to these examples. First, the conditions of the kneading apparatus used in the present invention are shown in Table 1.
Table 2 shows the physical properties of the release agent used.

[0042]

[Table 1]

[0043]

[Table 2] Example 1 Styrene-n-butyl acrylate copolymer 100 parts by weight Magnetic iron oxide 80 parts by weight Positive charge control agent (nigrosine) 2 parts by weight Release agent (1) 4 parts by weight The above materials were mixed with a Henschel mixer and then kneaded. After melt-kneading under the condition (1), the mixture was cooled and solidified by a cooling press and a cooling conveyor, and then pulverized and classified. The weight average diameter of the classified product was 8 μm. The content of the release agent contained in the classified product and the classified fine powder after the classification was determined from the DSC (differential scanning calorimeter) measurement of the heat of fusion derived from the release agent per unit weight. Table 3 shows the content ratio (classified fine powder / classified product). Since the released release agent is light in weight, it is concentrated in the classified fine powder at the time of classification and is contained in a large amount. Therefore, when the dispersion of the release agent is poor, a free release agent is generated, and the content ratio is increased. In Example 1, this value is small, and the dispersion of the release agent is very good. Also, by microscopic observation in the classified product,
No release agent was released. A copy test of a commercially available electrophotographic copying machine NP-2020 (manufactured by Canon Inc.) was performed on a toner obtained by externally adding hydrophobic colloidal silica to the obtained classified product. An image was obtained, and no problem occurred even after copying 10,000 sheets.

Example 2 Crosslinked polyester 100 parts by weight Magnetic iron oxide 60 parts by weight Negative charge control agent (monoazo metal complex) 1 part by weight Release agent (2) 4 parts by weight After mixing the above materials with a Henschel mixer, kneading conditions After melt-kneading in (2), the mixture was cooled and solidified by a cooling press and a cooling conveyor, and then pulverized and classified. The weight average diameter of the classified product was 12 μm. Table 3 shows the content ratio of the release agent contained in the classified product after classification and the classified fine powder (classified fine powder / classified product). When hydrophobic colloidal silica was externally added and printed out with a commercially available laser beam printer LBP8II (manufactured by Canon Inc.), a good printed image was obtained up to the use of the cartridge.

Example 3 100 parts by weight of styrene-n-butyl acrylate copolymer 100 parts by weight of magnetic iron oxide 3 parts by weight of positive charge control agent (triphenylmethane compound) 4 parts by weight of release agent (3) 4 parts by weight of Henschel mixer After melt-kneading under kneading conditions (3), the mixture was solidified by cooling with a cooling press and a cooling conveyor, and then pulverized and classified. The weight average diameter of the classified product was 6 μm. Table 3 shows the content ratio of the release agent contained in the classified product after classification and the classified fine powder (classified fine powder / classified product).
After externally adding hydrophobic colloidal silica, a copying test similar to that in Example 1 was performed. As a result, a good image was obtained and no trouble occurred.

Example 4 Styrene-n-butyl acrylate copolymer 100 parts by weight Copper phthalocyanine 4 parts by weight Positive charge control agent (quaternary ammonium salt) 3 parts by weight Release agent (4) 3 parts by weight The above materials were mixed with a Henschel mixer. After mixing, the mixture was melted and kneaded under kneading conditions (4), then cooled and solidified by a cooling press and a cooling conveyor, and then pulverized and classified. The weight average diameter of the classified product was 10 μm. Table 3 shows the content ratio of the release agent contained in the classified product after classification and the classified fine powder (classified fine powder / classified product). Using a commercially available electrophotographic copying machine NP-1215 (manufactured by Canon Inc.), after externally adding hydrophobic colloidal silica, mixing with a carrier to form a two-component developer, a copying test was performed, and good results were obtained. There were no practical problems.

Comparative Example 1 The materials of Example 1 were mixed with a Henschel mixer, melt-kneaded under kneading conditions (5), solidified by cooling with a cooling press and a cooling conveyor, and then pulverized and classified. The weight average diameter of the classified product was 8 μm. Table 3 shows the content ratio of the release agent contained in the classified product after classification and the classified fine powder (classified fine powder / classified product). Dispersion was rather poor, and a free release agent was generated.
After the hydrophobic colloidal silica was externally added, a copying test similar to that in Example 1 was carried out. As a result, a black spot-like fog having a free release agent as a nucleus was observed at an early stage. Further, when copying was continued, the release agent agglomerated on the cleaning blade, resulting in poor cleaning.

[0048]

[Table 3]

[0049]

By using the kneading method of the present invention,
The re-aggregation of the release agent can be prevented, and a toner composition having good dispersibility of the release agent can be obtained. Therefore, the generation of free release agent during pulverization and classification is small, and when used as a toner,
Does not adversely affect developability or durability.

[Brief description of the drawings]

FIG. 1 is a schematic view of a kneading apparatus suitable for the present invention.

FIG. 2 is a detailed view of a paddle in the kneading apparatus of FIG.

FIG. 3 is a schematic view showing an example of a paddle in a screw section of a kneading apparatus.

FIG. 4 is a schematic view showing an example of a paddle in a kneading section of the kneading apparatus.

FIG. 5 is a schematic view showing another example of the paddle in the kneading section of the kneading apparatus.

FIG. 6 is a schematic view showing another example of the paddle in the kneading section of the kneading apparatus.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroaki Kawakami 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Masaji Fujiwara 3-30-2 Shimomaruko, Ota-ku, Tokyo (56) References JP-A-3-149567 (JP, A) JP-A-2-97969 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 9 / 08

Claims (1)

(57) [Claims] 1. A method for producing a toner composition by melting and kneading a raw material mixture containing at least a binder resin, a colorant, and a release agent by using an extruder, wherein the extruder includes a raw material charging port and It is a kneading device that has a discharge port and a paddle is provided in the cylinder in the axial direction. The heating temperature of the discharge port cylinder is at least 10 ° C lower than the heating temperature of the cylinder on the most discharge side paddle section. A method for producing a toner composition.