JP2009229759A - Manufacturing method of electrophotographic toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of an electrophotographic toner can easily obtain toner characteristics for meeting demands of users by enabling easy adjustment of the developing amount. <P>SOLUTION: The method includes a step of mixing first toner particles and second toner particles having the same softening point as that of the first toner particles and a volume average particle size smaller than that of the first toner particles. The developing amount is controlled by adjusting the compounding amount of the first toner particles and the second toner particles. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a method for producing an electrophotographic toner, and more particularly, to a method for producing an electrophotographic toner capable of adjusting the development amount.

  In recent years, printers have been changing from monochrome to color. In particular, printers used in offices are commonly used by multiple departments, so the number of prints increases. Therefore, for reasons such as higher speed, durability, and running costs, electrophotographic lasers are used. A printer is selected.

  In order to satisfy such high-speed printing, durability, running cost, and other qualities, various properties are required for the toner. In addition, there are various usage environments, usage frequencies, printing contents, and printing media of users, and it is very difficult to provide a printer that can satisfy all users.

  As a specific usage situation of the user, for example, there is a case where color printing is hardly performed and monochrome printing with a low printing rate is mainly performed, or color printing with a high printing rate such as an advertisement is continuously printed. Since it is not uncommon for users to use such extreme usage, the degree of toner degradation will vary greatly.

  Furthermore, there is a request from users who frequently perform monochrome printing as described above to reduce the consumption of color toner with little printing. However, with toner with a reduced development amount, the image density drops, and a user who uses an image output by a printer as an advertisement cannot be satisfied.

  It is possible to adjust the parameters related to development by adjusting the settings of the manual of the printer and adjust the image to your liking to some extent, but the adjustment range is limited, and it is possible to obtain an image that is satisfactory for the user I can not say. In addition, although it is possible to customize the toner for a specific user, when the number of users increases, the type of toner increases, making it difficult to adjust the production plan and the like.

  It is known to obtain a toner having specific characteristics by mixing a plurality of types of toner. For example, a toner having a low softening point and a large particle size mixed with a toner particle having a high softening point and a small particle size to improve blocking properties (see, for example, Patent Documents 1 and 2), A toner that can obtain a high image density over a long period of time by mixing a toner having a large particle size and a large absolute value of charge amount and a toner having a small particle size and a small absolute value of charge amount (for example, see Patent Document 3). is there.

However, in the former toner in which the softening point is changed between a toner particle having a large particle size and a toner having a small particle size, the charge rates are different because the materials of the two toners are different, and the charging becomes uneven. There is a problem that aggregation easily occurs. In general, a toner having a large particle size has a small charge amount. Therefore, in order to obtain the latter toner having a large charge amount of a toner having a large particle size, the type of resin or the amount of charge control agent is changed. Such a special operation is necessary, and even by such an operation, the range of change in the development amount is narrow, and it has been difficult to obtain a toner exhibiting a development amount suitable for a specific application.
JP-A-60-188957 JP-A-10-177274 JP-A-11-24311

  The present invention has been made under the circumstances as described above, and provides a method for producing an electrophotographic toner capable of easily adjusting a developing amount and easily obtaining toner characteristics meeting a user's request. The purpose is to provide.

  In order to solve the above-described problem, an embodiment of the present invention provides a first toner particle, a second softening point that is the same as that of the first toner particle, and a second volume average particle size that is smaller than that of the first toner particle. A method for producing an electrophotographic toner, comprising: a step of mixing the toner particles; and a development amount is controlled by adjusting a blending amount of the first toner particles and the second toner particles. provide.

  In such an electrophotographic toner manufacturing method, the amount of the external additive contained in the second toner particles can be made larger than the amount of the external additive contained in the first toner particles.

  Further, the charge amount of the second toner particles can be made larger than the charge amount of the first toner particles.

  The difference in volume average particle diameter between the first toner and the second toner can be 2 μm or more.

  According to one embodiment of the present invention, there is provided a method for producing an electrophotographic toner that can easily adjust the development amount and can easily obtain toner characteristics that meet the user's request.

  Hereinafter, embodiments of the present invention will be described.

  An electrophotographic toner manufacturing method according to an embodiment of the present invention is characterized in that a plurality of toners having different volume average particle diameters and the same softening point are mixed. That is, a plurality of types of toners having the same softening point and made of the same material and having different volume average particle diameters are separately manufactured and then mixed to obtain one type of electrophotographic toner.

  The present inventors have developed a toner with a small average particle size with a small development amount, whereas a toner with a large average particle size has a large development amount. By mixing these toners, the development amount can be appropriately controlled. I found. That is, it has been found that the development amount can be increased by increasing the mixing ratio of the toner having a large average particle diameter with respect to the toner having a small average particle diameter. Based on such knowledge, for applications where a small amount of development is required such as monochrome printing, the mixing ratio of toner having a large average particle size is reduced, and for applications where a large amount of development is required such as color printing, It is possible to control the development amount of the toner in accordance with the application, such as increasing the mixing ratio of the toner having a large average particle diameter.

  In particular, by increasing the amount of the external additive for a toner having a small average particle size and decreasing the amount of the external additive for a toner having a large average particle size, the fluidity of the entire toner is made uniform. be able to.

  As described above, toners having a low softening point and a large particle size and toner particles having a high softening point and a small particle size are mixed to improve blocking properties. Therefore, it is necessary to change the type of the binder resin. If the type of the binder resin is changed, the charge rate is different. Further, a toner in which a toner having a large particle size and a large absolute value of charge amount and a toner having a small particle size and a small absolute value of charge amount are mixed is also known. The charge amount of toner having a large particle size is small. In general, a toner having a large particle size has a small charge amount, and therefore the toner according to the present invention can be obtained by mixing toners of the same material without changing the material of the resin.

  Therefore, the method for producing an electrophotographic toner according to an embodiment of the present invention has an excellent effect that a toner having a desired development amount can be obtained easily and at low cost.

  The difference in the volume average particle size of the plurality of types of toners is desirably 2 μm or more. If the difference in volume average particle diameter is less than 2 μm, the range in which the toner development amount can be controlled is narrow, which is not desirable.

  Hereinafter, a method for producing an electrophotographic toner according to an embodiment of the present invention will be specifically described.

  As described above, in the embodiment of the present invention, the toner having a small average particle diameter and the toner having a large average particle diameter before mixing are both the same as those of the conventional toner, and are conventionally known. It can manufacture by the method of.

  First, a raw material mixture containing a binder resin, a colorant, a charge control agent, a release agent and the like is mixed using a mixer. As a mixing machine, arbitrary things, such as a Henschel mixer, a super mixer, a V-type blender, and a Nauta mixer, can be used.

  Usable binder resins can be selected from a wide range including known ones. Specific examples include styrene resins such as polystyrene, styrene-acrylic acid ester copolymers, styrene-methacrylic acid copolymers, and styrene-butadiene copolymers, saturated polyester resins, unsaturated polyester resins, and epoxy resins. Phenolic resin, coumarone resin, xylene resin, vinyl chloride resin, polyolefin resin and the like can be exemplified, and two or more of these resins may be used in combination. Of these resins, polyester resins are preferred.

  As the charge control agent and the release agent, any of those usually used for electrophotographic toners can be used.

  The raw material mixture is then fed to a kneader where it is melt kneaded. As the kneading machine, any type of extrusion kneading machine such as a twin-screw extrusion kneading machine and a single-screw extrusion kneading machine, an open roll type kneading machine such as a continuous two-roll mill, a continuous three-roll mill, and a batch roll mill can be used. Things can be used.

  The melt-kneaded product discharged from the kneader is usually cooled, pulverized, and classified according to a method used for toner production to obtain a toner particle matrix having a predetermined average particle diameter. The cooling means, the pulverizing means, and the classification means are not particularly limited, and those usually used for toner production can be employed. For example, a cooling means by rolling or blowing an air flow can be used for cooling, and an airflow pulverizer such as a collision plate pulverizer can be used for pulverization, and various airflow classifiers can be used for classification. Can be used. In one embodiment of the present invention, by changing the pulverization classification conditions, a plurality of types of toner particle bases having different average particle diameters, in particular, average particle diameter differences of 2 μm or more are generated.

  By adding inorganic particles hydrophobized with silicone oil to each of a plurality of types of toner particle bases having different average particle diameters obtained in this manner, and mixing and stirring, a plurality of types of toner particles having different average particle diameters are mixed. An electrophotographic toner is obtained. In this case, it is desirable to make the addition amount of the external additive contained in the toner particles having a large average particle diameter smaller than the addition amount of the external additive contained in the toner particles having a small average particle diameter. By doing so, the fluidity can be matched, and a toner with uniform fluidity can be obtained.

  In the method for producing an electrophotographic toner according to an embodiment of the present invention, a plurality of electrophotographic toners having different average particle diameters are produced as described above, and then mixed. Mixing can be performed using a normal mixer such as a V-type blender.

Examples Hereinafter, examples and comparative examples of the present invention will be shown, and the present invention will be described more specifically.

  First, a toner having an average particle diameter of 9 μm and a toner having an average particle diameter of 6 μm used in Examples and Comparative Examples were prepared as follows.

<Preparation of toner with an average particle size of 9 μm>
92 parts by mass of a polyester resin (softening point 135 ° C.) as a binder resin and C.I. 4 parts by weight of I Pigment Red 57: 1, 1 part by weight of the charge control agent “LR-147” (manufactured by Nippon Carlit Co., Ltd .: organoboron compound), and 3 parts by weight of the release agent “Carnauba wax No. 1 powder” (Yoyuki Kato) The parts were mixed using a Henschel mixer (Mitsui Mining Co., Ltd.).

  The mixed powder is melt-kneaded with a twin-screw kneader (screw diameter: 43 mm, L / D = 34), stretched, cooled, and coarsely crushed with a Rotoplex (manufactured by Hosokawa Micron Co., Ltd., 2 mm screen). -Using a wind classifier, pulverization classification was performed so that the volume average particle diameter of the toner was 9.0 μm, and colored particles were obtained.

  As external additives, 2 parts by mass of “NY50” (manufactured by Nippon Aerosil Co., Ltd .: hydrophobic silica) and 0.2 part by mass of “H3004” (manufactured by Clariant: hydrophobic silica) are added to 100 parts by mass of the obtained colored particles. Partly added and mixed with a Henschel mixer to obtain a toner. The obtained toner had a softening point of 129.6 ° C.

<Preparation of toner with an average particle diameter of 6 μm>
92 parts by mass of a polyester resin (softening point 135 ° C.) as a binder resin and C.I. 4 parts by weight of I pigment red 57: 1, 1 part by weight of “LR-147” (manufactured by Nippon Carlit Co., Ltd .: organoboron compound) as a charge control agent, and “Carnauba wax No. 1 powder” (Yoyuki Kato) as a release agent Three parts by mass were mixed using a Henschel mixer (Mitsui Mining Co., Ltd.).

  The mixed powder is melt-kneaded with a twin-screw kneader (screw diameter: 43 mm, L / D = 34), stretched, cooled, and coarsely crushed with a Rotoplex (manufactured by Hosokawa Micron Co., Ltd., 2 mm screen). -Using a wind classifier, pulverization classification was performed so that the volume average particle diameter of the toner was 6.0 μm, and colored particles were obtained.

  3 parts by mass of “NY50” (manufactured by Nippon Aerosil Co., Ltd .: hydrophobic silica) and 0.5 part by mass of “H3004” (manufactured by Clariant: hydrophobic silica) are added to 100 parts by mass of the obtained colored particles. The toner was added and mixed with a Henschel mixer to obtain a toner. The obtained toner had a softening point of 129.5 ° C.

  Compared with the 9.0 μm toner, the toner has the same composition of the toner material, and therefore the softening point is almost the same, but the average particle diameter of the toner and the amount of the external additive are different.

  The toner having an average particle diameter of 9.0 μm and the toner having an average particle diameter of 6.0 μm obtained as described above were weighed in the proportions shown in the following table, and then stored in a V-type mixer having a capacity of 10 L, and the rotation speed 9 toner samples were obtained by mixing at 30 rpm for 3 minutes.

Comparative Example A toner having an average particle diameter of 6 μm was prepared in the same manner as described above except that a (polyester) resin having a softening point (145 ° C.) was used as the binder resin. This toner was mixed with the toner having an average particle diameter of 9 μm obtained as described above, and nine toner samples were obtained.

  The obtained toner sample was measured for physical properties, and the particle size and charge amount were measured.

  The softening point of the binder resin and toner was measured using the following apparatus under the following conditions.

Apparatus: Flow tester (manufactured by Shimadzu Corporation, CFT-500D)
Sample: 1g
Temperature increase rate: 6 ° C / min Load: 20kg
Nozzle: 1mm diameter, 1mm length
1/2 method: The temperature at which half of the sample flowed out was taken as the softening point.

<Evaluation conditions for physical properties>
1. The particle size was measured under the following conditions using the following apparatus.

Device: Multisizer III (Coulter)
Sample: A small amount of sample, purified water, and a surfactant were placed in a beaker and dispersed with an ultrasonic cleaner.

  Measurement: The aperture was 50 μm, the count was 50,000, and the volume average particle size was obtained.

2. Charge amount Using the following apparatus, measurement was performed under the following conditions.

Device: Blow-off charge measurement device (Toshiba Chemical)
Blow pressure: 1kgf / cm ²
Blow time: 20 sec
Mesh: 400 mesh Sample amount: 200 mg
Debedding conditions 9.7 g of carrier (Powdertech FT-150) and 0.3 g of toner were placed in a 20 cc screw tube, set in a ball mill, and stirred at 100 rpm for 10 minutes. The measurement environment was 25 ° C. and 50% RH.

Test-1 (development amount)
Non-magnetic one-component developing device “Casio Page Prest N-5” (manufactured by Casio Computer Co., Ltd .: 29 color printers per minute, process speed 129 mm / sec) with toner mounted in normal environment (25 ° C., 50% In (RH), a solid image was printed, and the door was opened in the middle of printing to forcibly stop, and an image with no toner fixed was collected. The toner on the obtained unfixed image was sucked with a vacuum cleaner, and the development amount (mg / cm ² ) was determined from the printing area and the toner mass.

Test-2 (image density)
A solid image is printed using the same apparatus as in Test-1. The image density was measured using a spectrocolorimetric densitometer (X-Rite 938) manufactured by X-Rite. X-Rite was set with a D65 light source m, a viewing angle of 2 degrees, and a measurement diameter of 4 mm.

The above measurement results and test results are shown in Tables 1 and 2 below.

  From Table 1 above, it was found that in the toner obtained by mixing the toner having a volume average particle diameter of 6 μm and the toner having 9 μm, the development amount increases as the ratio of the toner having an average particle diameter of 9 μm increases. As the development amount increased, the image density tended to increase. Thus, it can be seen that by changing the mixing ratio of toners having different particle diameters, the development amount can be adjusted, and a toner having a development amount suitable for the user's request can be obtained.

  On the other hand, when toners using binder resins having different volume average particle diameters and different softening points are mixed, the softening point varies depending on the mixing ratio as shown in Table 2 above. When the softening point is high, a cold offset occurs, and the width of the blending ratio that can be practically used is narrowed. As a result, the adjustment range of the development amount is narrowed.

Claims (4)

  Mixing the first toner particles with the second toner particles having the same softening point as the first toner particles and a volume average particle size smaller than the first toner particles; A method for producing an electrophotographic toner, wherein the development amount is controlled by adjusting a blending amount of the first toner particles and the second toner particles.   2. The electrophotographic toner according to claim 1, wherein the amount of the external additive contained in the second toner particles is larger than the amount of the external additive contained in the first toner particles. Method.   3. The method for producing an electrophotographic toner according to claim 1, wherein the charge amount of the second toner particles is larger than the charge amount of the first toner particles.   The method for producing an electrophotographic toner according to claim 1, wherein a difference in volume average particle diameter between the first toner and the second toner is 2 μm or more.