JP2008281924A - Method for manufacturing toner for electrostatic charge image development - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a toner for electrostatic charge image development by which a colorant and a release agent can be uniformly dispersed in a resin without increasing cost of manufacturing. <P>SOLUTION: The method for manufacturing a toner for electrostatic charge image development includes: a step of obtaining a mixture by adding water or a surfactant to a primary material including at least a resin, a colorant and a release agent and mixing these; a kneading step of obtaining a kneaded product by heat-melting and kneading the mixture with an open roll type continuous kneading machine having heating and cooling functions; a pulverization step; and a classification step. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a toner for developing an electrostatic image used in electrophotography, electrostatic recording and the like.

  The developer used in an electronic copying machine or the like is temporarily attached to an image carrier such as a photoreceptor on which an electrostatic charge image is formed in the development process, and then transferred from the photoreceptor to transfer paper in the transfer process. Then, it is fixed on the copy paper surface in the fixing step. At that time, as a developer for developing an electrostatic charge image formed on the latent image holding surface, a two-component developer composed of a carrier and a toner and a one-component developer that does not require a carrier (magnetic toner, non-toner) Magnetic toner) is known.

The toner contained in the developer is composed mainly of a binder resin in the case of a non-magnetic toner, and a binder resin and magnetic powder in the case of a magnetic toner, and is melt-kneaded with, for example, a colorant or a release agent. These can be produced by dispersing these in the resin, cooling in the cooling step, pulverizing the cooled product in the pulverizing step, and performing a classification step of classifying only to a predetermined size.
In this melt-kneading step, a colorant, a release agent, and the like are uniformly dispersed in the resin, so that the chargeability of the obtained toner is uniform, and in order to improve copy image quality and durability. It becomes an important factor.
Therefore, rather than directly kneading the resin and the colorant itself (so-called raw pigment), a so-called master batch in which the colorant is dispersed in a high concentration in the resin in advance is manufactured, A method for producing a toner by melt-kneading with a release agent or the like has been proposed (see, for example, Patent Document 1).
According to this method, the dispersion of the colorant can be made uniform, but the cost increases due to an increase in the production process of the master batch, and not only the toner cannot be produced at low cost, but also the uniform dispersion of the release agent is achieved. It was not enough.

JP 2001-75307 A

  The present invention has been made in view of the above-described problems, and the object of the present invention is to uniformly disperse the colorant and the release agent in the resin without increasing the production cost. Another object of the present invention is to provide a method for producing a toner for developing an electrostatic charge image (hereinafter also referred to as toner).

  The present invention has solved the above problems by the following technical configuration.

(1) A step of adding and mixing water or a surfactant to a raw material comprising at least a resin, a colorant and a release agent to obtain an additive mixture, and heating the additive mixture by an open roll type continuous kneader having heating and cooling functions A method for producing a toner for developing an electrostatic charge image, comprising: a kneading step for obtaining a kneaded product by melt kneading, a pulverizing step, and a classification step.
(2) The method for producing a toner for developing an electrostatic charge image according to the above (1), wherein the surfactant is a nonionic surfactant.
(3) The method for producing a toner for developing an electrostatic charge image according to (1), wherein the surfactant is any one of alkyl glucoside, polyethylene glycol, and polyvinyl alcohol.

  According to the present invention, it is possible to provide a method for producing an electrostatic charge image developing toner capable of uniformly dispersing a colorant and a release agent in a resin without increasing production costs.

Hereinafter, the present invention will be described in detail.
Examples of the resin used in the present invention include polystyrene, polychlorostyrene, poly-α-methylstyrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer, and styrene-vinyl chloride copolymer. Styrene-vinyl acetate copolymer, styrene-acrylate copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate) Copolymer and styrene-phenyl acrylate copolymer), styrene-methacrylic acid ester copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer). And styrene-phenyl methacrylate copolymer, etc. , Styrene resins (monopolymer or copolymer containing styrene or a styrene substitution product), vinyl chloride resin, rosin, such as styrene-α-chloroacrylic acid methyl copolymer and styrene-acrylonitrile-acrylic acid ester copolymer Modified maleic acid resin, phenol resin, epoxy resin, polyester resin (including saturated and unsaturated), polyethylene resin, polypropylene resin, ionomer resin, polyurethane resin, silicone resin, ketone resin, ethylene-ethyl acrylate copolymer resin, xylene resin , Polyvinyl butyral resin, polycarbonate resin, and the like. Preferred resins for use in the present invention include styrene resins and polyester resins.
Moreover, the said resin is not restricted to being used alone, but can be used in combination of two or more.

The flow softening temperature (Tm) of the resin is preferably about 80 to 150 ° C, more preferably about 90 to 140 ° C.
Below 80 ° C, the paper fixing temperature is low and good, but hot offset is likely to occur, and the toner tends to be crushed inside the developing tank, causing a spent phenomenon that the toner adheres to the carrier surface and doctor blade. As a result, the charging characteristics are deteriorated, and the durability of the developer is deteriorated.
On the other hand, when the temperature is higher than 150 ° C., there are problems such as high fixing temperature on the fixing temperature paper and poor toner pulverization.

  The glass transition temperature of the resin is preferably about 45 ° C. or higher, and if it is less than 45 ° C., the toner has a poor storage stability such as causing the toner to agglomerate or stick when left at a high temperature of 40 ° C. for a long time. Therefore, there is a problem in use such that toner agglomerates are easily generated, and further, agglomerates are easily generated by adhering to a screen, a side wall or the like of a sieving apparatus.

  The resin may be produced by known solution polymerization, suspension polymerization, bulk polymerization, emulsion polymerization or the like, and the polymerization method of the low molecular weight body and the high molecular weight body may be different as required.

Each test method of the resin used in this specification will be described below.
[Flow softening temperature (Tm)]
In a flow tester (CFT-500 manufactured by Shimadzu Corporation), a sample 1 g was measured under the conditions of a die of 1 mm × 10 mm nozzle, a load of 30 kg, a preheating time of 50 ° C. for 5 minutes, and a heating rate of 3 ° C./min. The temperature at the midpoint of the distance from the start to the end of the flow is set as the softening temperature.

  [Glass transition temperature (Tg)] In a differential thermal analyzer (DTA-40, manufactured by Shimadzu Corporation), a tangent line is formed at the start of transition (inflection) of the curve measured at a temperature rising rate of 10 ° C / min. The intersection temperature is taken as the glass transition temperature.

Next, as the colorant used in the present invention, carbon black, titanium oxide, zinc white, alumina white, calcium carbonate, ultramarine, bitumen, phthalocyanine blue, phthalocyanine green, Hansa Yellow G, rhodamine dye, chrome yellow, quinacridone, Coloring agents such as benzidine yellow, rose bengal, triallylmethane dye, anthraquinone dye, monoazo and diazo dye / pigment can be used singly or in combination.
The colorant content may be an amount sufficient to color the toner so that a visible image can be formed by development. For example, 1 to 20 parts by weight, and further 3 to 15 parts by weight with respect to 100 parts by weight of the resin. Part is preferred.

The release agent used in the present invention includes hydrocarbon waxes such as polypropylene wax, polyethylene wax and Fiescher-Tropsch wax, and natural ester waxes such as synthetic ester waxes, carnauba wax and rice wax. There are selected release agents and the like.
Of these, natural ester waxes such as carnauba wax and rice wax, synthetic ester waxes obtained from polyhydric alcohols and long-chain monocarboxylic acids, and hydrocarbon waxes such as Fischer-Tropsch wax are preferably used.
As the synthetic ester wax, for example, WEP-8 (manufactured by NOF Corporation) is suitably used.
The content of the release agent is 1 to 10 parts by weight, preferably 3 to 8 parts by weight with respect to 100 parts by weight of the resin.

Further, a positively or negatively chargeable charge control agent may be used alone or in combination for the toner, and the amount used may be selected according to the desired charge amount. For example, about 0.05 to 10 parts by weight is preferable with respect to 100 parts by weight of the resin.
Examples of the positive charge control agent include nigrosine dyes, quaternary ammonium salt compounds, triphenylmethane compounds, imidazole compounds, and polyamine resins.
Examples of negative charge control agents include metal-containing azo dyes such as Cr, Co, Al, and Fe, salicylic acid metal compounds, alkyl salicylic acid metal compounds, and curix arene compounds.

Next, the toner manufacturing method of the present invention will be described with reference to FIG.
The toner production method of the present invention has an addition and mixing step of adding and mixing water or a surfactant to a raw material consisting of at least a resin, a colorant and a release agent to obtain an addition mixture, and has a function of heating and cooling the addition mixture It has the kneading | mixing process which obtains a kneaded material by hot-melt-kneading with an open roll type continuous kneader.
In the addition and mixing step, water or a surfactant is added to the raw material obtained by weighing and mixing a predetermined amount of at least a resin, a colorant, and a release agent and further mixed to obtain an addition mixture.
Alternatively, a predetermined amount of a resin, a colorant, a release agent, water, or a surfactant may be weighed and mixed at a time to obtain an additive mixture.
Examples of the mixing device include a double cone mixer, a V-type mixer, a drum-type mixer, a super mixer, a Henschel mixer, and a Nauter mixer.

As the water, industrial water, distilled water or the like can be used.
As the surfactant, those having thermal stability at the time of kneading are preferable, and nonionic surfactants and the like are preferable. Among them, alkyl glucoside, polyethylene glycol, and polyvinyl alcohol are more preferable. The surfactant is preferably added to an industrial water, distilled water or the like to make a 5 to 15 wt% aqueous solution.
Water or a surfactant may be added directly to the raw material, or may be added in the form of water droplets using a commercially available supply device such as a plunger pump or a gear pump.
Further, the addition amount is preferably 0.1 to 1.5 parts by weight of the surfactant with respect to 100 parts by weight of the raw material.
In this case, when the surfactant is less than 0.1 parts by weight, it is difficult to obtain a uniform dispersion of the colorant and the release agent in the resin, and when it is more than 1.5 parts by weight, the uniform dispersion is difficult. It is not preferable.

  Next, in the kneading step, the additive mixture is hot-melt kneaded with an open roll type continuous kneader having heating and cooling functions to obtain a kneaded product in which the colorant and the release agent are uniformly dispersed in the resin.

  A kneaded product in which the colorant and the release agent are uniformly dispersed in the resin is manufactured by adding water or a surfactant and kneading using an open roll type continuous kneader having heating and cooling functions. can do. In addition, according to the present invention, since it is not necessary to preliminarily disperse the colorant in the master batch, the manufacturing time can be reduced without increasing the number of manufacturing steps.

  In the open roll type continuous kneader used in the present invention, two rolls of a front roll and a back roll are arranged in parallel, and kneading is performed by a mechanical shear force when the raw material passes through the gap between the two rolls. Is to do. In addition, this roll has spiral grooves and lateral grooves, and these grooves allow the raw material to bite into the gap between the rolls, and from the raw material supply unit provided near one end of the roll, provided near the other end of the roll. The conveyance of the kneaded material to the kneaded material discharge portion is promoted. The raw material can be appropriately supplied not only from the roll end but also from the first half, middle and second half of the roll according to the properties of the raw material.

The open roll type continuous kneader has heating and cooling functions by passing a heating medium such as oil or hot water through the front roll and a cooling medium such as water through the back roll. Thereby, kneading can be performed at an appropriate temperature. Moreover, by performing cooling with kneading, it is not necessary to go through a cooling process as a separate process, and the process can proceed directly to the pulverization process.
As an open roll type continuous kneader, there can be used a kneedex manufactured by Mitsui Mining Co., Ltd.

  Next, in the pulverization step, coarse pulverization is performed with a crusher, hammer mill, feather mill, or the like, fine pulverization is performed with a jet mill, a high-speed rotor rotary mill, or the like, and pulverized to a predetermined toner particle size step by step.

In the classification step, the toner is classified by an inertia classification type elbow jet, a centrifugal classification type microplex, a DS separator, a dry air classifier, or the like to obtain a classified toner having a volume average particle size of 3 to 15 μm.
Moisture remaining in the toner particles and the surfactant can be removed in the air stream of these pulverization and classification processes. If moisture and a surfactant remain in the toner particles, the environmental stability of the toner particles is lowered. Therefore, it is preferable to completely remove the toner particles.
The coarse powder generated in the classification process may be returned to the pulverization process, and the generated fine powder may be returned to the kneading process of the additive mixture and reused.

When an external additive is attached to the classified toner, an external addition step is performed.
A predetermined amount of the classified toner and various known external additives are blended, and the mixture is stirred and mixed with a high-speed stirrer or the like that gives a shearing force to powder such as a Henschel mixer or a super mixer.
At this time, since heat is generated inside the external additive machine and it becomes easy to generate agglomerates, it is preferable to adjust the temperature by means such as cooling the periphery of the container part of the external additive machine with water. The internal material temperature is preferably below the control temperature of about 10 ° C. lower than the glass transition temperature of the resin.

As the external additive, various inorganic or organic external additives can be used. In particular, inorganic substances such as silica, titanium oxide, alumina, zinc oxide, and magnesium oxide are used for improving the fluidity of the toner and suppressing the aggregation. A fine powder is preferred.
The amount of the external additive to be mixed varies depending on the external additive to be used and the average particle size, particle size distribution, etc. of the toner particles, but an amount for obtaining the desired toner fluidity can be appropriately selected. Generally, 0.05 to 10 parts by weight, and further 0.1 to 8 parts by weight is preferable with respect to 100 parts by weight of toner particles.
If the mixing amount is less than 0.05 parts by weight, the fluidity improving effect is small, the storage stability performance at high temperature is poor, and if the mixing amount is more than 10 parts by weight, filming is caused on the photosensitive member by a partially free external additive. This is undesirable because it occurs or accumulates in the developing tank and causes problems such as deterioration of the charging function of the developer.
In addition, the external additive is more preferably hydrophobized with a treatment agent such as silane coupling in the case of an inorganic fine powder from the viewpoint of stability in a high-humidity environment. For example, dimethyldichlorosilane, monooctyltrichlorosilane, hexamethyldisilazane, or silicone oil may be used as a processing agent for imparting negative charge, and aminosilane or the like may be used as a processing agent for imparting positive charge.

  In addition, for the purpose of resistance adjustment, abrasives, etc. as toner external additives, magnetite, ferrite, conductive titanium, antimony oxide, tin oxide, cerium oxide, hydrotalcite compounds, acrylic beads, An appropriate amount of fine powders such as silicone beads and polyethylene beads may be mixed, and the mixing amount is preferably 0.005 to 10 parts by weight with respect to 100 parts by weight of the toner.

  The obtained toner is a one-component developer not using a carrier (a magnetic one-component toner containing a magnetic material such as magnetite or a non-magnetic one-component toner containing no magnetic material), or iron powder, ferrite, magnetite. And a two-component developer mixed with a magnetic carrier such as a magnetic resin carrier.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. In addition, the compounding quantity of a raw material is a weight part.

<Example 1>
First, the following raw materials were mixed for 10 minutes with a super mixer to obtain a raw material mixture.
-Polyester resin 89.0 parts (Made by Mitsubishi Rayon Co., Ltd., trade name: FC-433, Tm137 ° C, Tg57 ° C)
-Magenta pigment powder 5.0 parts (manufactured by Dainichi Seika Kogyo Co., Ltd., trade name: Red No. 8)
Charge control agent 1.0 part (manufactured by Nippon Carlit Co., Ltd., trade name: LR-147)
Ester wax 5.0 parts (manufactured by NOF Corporation, trade name: WEP-8, melting point 78 ° C.)
Furthermore, 6 parts of distilled water was added to the mixture and mixed for 2 minutes with a super mixer to obtain an additive mixture (addition mixing step).
And the temperature of a front roll is 80-100 degreeC using the open roll type continuous kneading machine (The Mitsui Mining Co., Ltd. make, brand name: Nidex MOS100-500) which has a heating and cooling function for the obtained addition mixture. And appropriately melted and kneaded under the conditions of a front roll speed of 60 rpm, a back roll cooling medium: water, a back roll speed of 45 rpm, an inter-roll gap of 0.5 to 1 mm, and a discharge rate of 4.0 kg / hr. A chip-shaped kneaded product was obtained (kneading step).
The obtained kneaded material is roughly pulverized with a hammer mill and then finely pulverized with a jet mill (pulverization step), classified with a dry air classifier (classification step), and a classified toner having a volume average particle diameter (Dv) of 8.5 μm. Got.

Next, 100 parts of the classified toner was added with the following external additive composed of silica, resin fine powder and titanium oxide, and mixed for 8 minutes with a 300 L Henschel mixer at a rotational speed of 1220 rpm (external addition process). No toner was obtained.
・ Silica 0.2 part (manufactured by Clariant Japan, average primary particle size 17.5 nm, specific surface area 140 m ² / g)
-Resin fine powder 0.3 part (product name: HYLAR461, manufactured by AUSIMINT)
・ 0.5 parts of titanium oxide (manufactured by Nippon Aerosil Co., Ltd., primary particle diameter 10 nm, BET specific surface area 65 ± 10, treating agent octylsilane)

<Example 2>
Example in the same manner as in Example 1 except that 6 parts of a 5% aqueous solution of a surfactant (polyethylene glycol manufactured by Nippon Oil & Fats Co., Ltd., trade name: PEG # 1000) was added instead of distilled water in the addition mixing step. 2 toner was obtained.

<Comparative Example 1>
A toner of Comparative Example 1 was obtained in the same manner as in Example 1 except that distilled water was not added.

<Comparative example 2>
In the kneading process, instead of an open roll type continuous kneader having heating and cooling functions, a continuous twin-screw extruder (manufactured by Ikegai Co., Ltd., trade name: PCM-35) is used to heat at a rotational speed of 200 rpm and a load current of 10A. A toner of Comparative Example 2 was obtained in the same manner as Example 1 except that the kneaded material was obtained by melt-kneading.
Table 1 shows the main conditions of Examples and Comparative Examples.

  Regarding the kneaded materials obtained during the production of Examples and Comparative Examples, cross-sectional electron micrographs were taken, the following maximum dispersion diameters were measured for the colorant and the release agent, and the results are shown in Table 2.

<Measurement method>
Maximum Dispersion Diameter Regarding the kneaded materials of Examples and Comparative Examples, cross-sectional scanning electron micrographs were taken, and the longest diameter of the largest colorant and release agent that appeared in granular form was defined as the maximum dispersion diameter (μm).
For the colorant, ◎: less than 0.5 μm, ◯: 0.5 μm or more and less than 1.0 μm, Δ: 1.0 μm or more and less than 5.0 μm, x: 5.0 μm or more.
In addition, the release agent was ◎: less than 0.1 μm, ◯: 0.1 μm or more and less than 0.5 μm, Δ: 0.5 μm or more and less than 1.0 μm, and x: 1.0 μm or more.

<Evaluation results>
In Example 1, the maximum dispersion diameter of the colorant was very good at less than 0.1 μm, and the maximum dispersion diameter of the release agent was good at 0.1 μm or more and less than 0.5 μm.
When the toner of Example 1 was printed using a non-magnetic one-component printer, a significant improvement in copy image quality and an improvement in durability performance were observed.
In Example 2, the maximum dispersion diameter of the colorant was considerably good when it was less than 0.5 μm, and the maximum dispersion diameter of the release agent was quite good when it was less than 0.1 μm.
When the toner of Example 2 was printed using a non-magnetic one-component printer, improvement in copy image quality and improvement in durability performance were observed.
On the other hand, in Comparative Example 1, the maximum dispersion diameter of the colorant was insufficient at 5.0 μm or more, and the maximum dispersion diameter of the release agent was good at 0.1 μm or more and less than 0.5 μm.
When the toner of Comparative Example 1 was printed using a non-magnetic one-component printer, there was a practical problem in copy image quality.
In Comparative Example 2, the maximum dispersion diameter of the colorant is good when it is 0.5 μm or more and less than 1.0 μm, and the maximum dispersion diameter of the release agent is slightly insufficient when it is 0.5 μm or more and less than 1.0 μm. .
When the toner of Comparative Example 2 was printed using a non-magnetic one-component printer, there was a practical problem in durability.

Flowchart showing a method for producing a toner for developing an electrostatic image

Claims (3)

A step of adding and mixing water or a surfactant to a raw material comprising at least a resin, a colorant, and a release agent to obtain an additive mixture, and hot melt kneading the additive mixture with an open roll type continuous kneader having heating and cooling functions And a kneading step for obtaining a kneaded product, a pulverizing step, and a classification step. The method for producing a toner for developing an electrostatic charge image according to claim 1, wherein the surfactant is a nonionic surfactant. 2. The method for producing a toner for developing an electrostatic charge image according to claim 1, wherein the surfactant is any one of alkyl glucoside, polyethylene glycol and polyvinyl alcohol.

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