JP2000275909A - Developer and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the developer good in fluidity and dispersibility and stable in chargeability characteristics during all the usable life. SOLUTION: This developer is manufactured by kneading toner materials so as to cause a displacement-strength curve to satisfy the following expressions: 11.094X-11.07<=Y<=30.161X-19.323, (1.0<=X<=2.0) at the time of compressing the toner particles, and adding external additives subjected to heat mixing treatment to the toner particles to firmly attach them to the toner particles in the temperature range of the glass transition start point and the glass transition point.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developer used for an electrophotographic apparatus or the like and a method for producing the same.

[0002]

2. Description of the Related Art Developers have various characteristics such as developability,
Durability, fixability, storage stability, environmental stability and the like are required.

[0003] These characteristics vary depending on the copying machine or the like to be used. When a developer is manufactured, its formulation and manufacturing conditions are determined so as to satisfy all these characteristics.

[0004] Materials used for the developer include, for example, a toner particle material such as a wax, a charge control agent, and a pigment which are added to the resin at the time of kneading, and an inorganic oxide which is adhered to the toner surface after kneading, pulverizing and classifying. And external additives such as fine particles, and the formulation affects the properties of the developer.

[0005] In particular, how the external additives are attached to the surface of the toner has a great effect on the characteristics of the developer. As such an external additive, generally, fine particles such as an inorganic oxide are adhered to the toner surface using a mixer such as a Nauta mixer, a turbulator, a granulator, etc., thereby improving the developability and storage stability of the toner. Was being planned.

In general, it is known that by adding an inorganic oxide such as silica, the chargeability is improved and high developability is obtained. At the same time, it is known that the fluidity of the toner is improved, so that the storage stability is improved. However, when the amount of such an inorganic oxide is increased, the inorganic oxide such as silica which is peeled off over a long period of time adheres to the carrier. There has been a problem that the image quality is deteriorated and the toner is stained inside the machine due to the shortage of the charge amount.

The same applies to the study of other manufacturing conditions, and the charge characteristics of the toner are controlled by appropriately dispersing the binder resin in the toner particle material and other materials.

For example, if the degree of mixing of the toner particle materials is not appropriate and the dispersion of the raw materials in the binder resin is poor, electric charges are likely to leak partially, appearing as dust fog on an image, or causing toner to develop in a developing machine. Since it is easily crushed, there is a problem that the carrier is contaminated and the electric resistance is impaired.

On the other hand, if the dispersion is extremely high, the toner resistance becomes high, causing problems such as difficulty in obtaining an image density.

[0010] From the above, an appropriate degree of dispersion of the raw material is required, but it is difficult to specify various degrees of dispersion of the material in the binder resin. For example, a thin slice obtained by slicing a kneaded toner mass is observed by TEM. Although sensory evaluations have been made, such quantification was not sufficient.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has good fluidity and dispersibility.
An object of the present invention is to provide a developer that has stable charging characteristics over its life and can obtain good image quality without causing toner scattering or the like.

Another object of the present invention is to provide a developer which has good fluidity and dispersibility, has stable charging characteristics over its life, and can provide good image quality without causing toner scattering or the like. To provide a method for manufacturing the same.

[0013]

The developer of the present invention comprises toner particles containing a colorant and a binder resin, and the toner particles having a temperature in the range of the glass transition endothermic onset temperature or the glass transition point temperature of the binder resin. The toner particles include an external additive adhered by heating and mixing, and the toner particles are characterized in that a displacement-strength curve at the time of compression satisfies the following relational expression.

11.094X-11.07≤Y≤30.
161X-19.323 (1.0 ≦ X ≦ 2.0) In the method for producing a developer according to the present invention, a step of forming toner particles containing a colorant and a binder resin, and a glass transition endothermic start of the binder resin Adhering an external additive to the toner particles by heating and mixing in a temperature atmosphere within a temperature range from a temperature to a glass transition temperature, wherein the toner particles are displaced during compression. -Characterized in that the strength curve satisfies the following relational expression.

11.094X-11.07≤Y≤30.
161X-19.323 (1.0 ≦ X ≦ 2.0)

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present inventors have focused on the addition of an external additive and the dispersion of a binder resin and a colorant in toner particles to improve the chargeability of a developer. As a result, the present invention has been accomplished.

The developer of the present invention comprises toner particles containing a colorant and a binder resin, and an external additive, wherein the external additive has a temperature within a range from the glass transition endothermic onset temperature to the glass transition point temperature of the binder resin. The toner particles are heated and mixed in a temperature atmosphere and adhered to the toner particles, and the toner particles have a displacement-strength curve upon compression satisfying the following relational expression.

11.094X-11.07≤Y≤30.
161X-19.323 (1.0 ≦ X ≦ 2.0) The method for producing a developer of the present invention is an example of a method for obtaining the developer, and includes a toner particle containing a colorant and a binder resin. And the step of mixing the external additive with the toner particles, wherein the mixing of the external additive is performed at a temperature in the range of the glass transition endothermic onset temperature or the glass transition point temperature of the binder resin. Displacement during compression of toner particles obtained by heating while heating to atmosphere-
The toner particles are formed such that the strength curve satisfies the following relational expression.

11.094X-11.07≤Y≤30.
161X-19.323 (1.0 ≦ X ≦ 2.0) According to the present invention, the external additive is mixed with the toner particles by heating the toner particles in an atmosphere in a temperature range from the glass transition endothermic onset temperature to the glass transition point temperature of the binder resin. Due to the treatment, it is firmly attached on the toner particles. This prevents the deterioration of the developer due to the exfoliation of the external additive, secures good fluidity,
Stable charging properties and sufficient storage and storage properties are obtained. In addition, since the amount of the external additive to be added can be increased as compared with the conventional one while maintaining stable chargeability, higher storage stability can be obtained.

FIG. 1 is a graph schematically showing the glass transition point endothermic initiation temperature and the glass transition point temperature.

The temperature range for adding the external additive is as shown in FIG. If the temperature exceeds the glass transition temperature Tg, the toner is fixed in the equipment and the toner becomes unusable.
Damage equipment.

If the temperature at the time of addition is lower than the temperature at which endothermic occurs at the time of measuring Tg, the effect of fixing the external additive is significantly reduced.

According to the present invention, for example, the degree of dispersion can be calculated from the approximate polar line of the displacement and mechanical strength obtained when compressing the toner particles while changing the combination of the load and the load speed during kneading at some points. Is obtained, the mixing is easily controlled so that the displacement-intensity curve of the toner particles during compression satisfies the above relational expression, and the kneading of the toner particles can be optimized.

FIG. 2 is a graph showing a displacement-intensity curve when the toner particles are compressed. The range of the displacement at the time of kneading the toner is desirably the shaded range shown in the figure.

As the binder resin, there can be used a copolymer of styrene and its substitute, which has been used as an ordinary binder resin for a toner, and an acrylic resin. In addition, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, polyurethane, polyamide, epoxy resin, phenol resin, urea resin and the like can be used alone or in combination.

As the coloring agent, carbon black, organic or inorganic pigments or dyes and the like are used.

If necessary, waxes for improving the anti-offset characteristic and a charge controlling agent for controlling the triboelectric charge amount can be added.

Examples of the external additives to be adhered to the toner surface for improving the developing property and the storage / storing property include silica fine particles, metal oxide fine particles, and a cleaning aid.

Examples of the silica particles include silicon diacid, aluminum silicate, sodium silicate, potassium silicate, zinc silicate, and magnesium silicate. Examples of the metal oxide particles include zinc oxide, titanium oxide, and oxide. Examples include aluminum, zirconium oxide, strontium titanate and barium titanate.

Examples of the cleaning aid include resin powders such as polymethyl methacrylate, polyvinylidene fluoride, and polytetrafluoroethylene. These external additives may have been subjected to a surface treatment such as a hydrophobic treatment.

[0031]

The present invention will be described below in detail with reference to examples.

The following materials were heated, melt-kneaded, cooled, pulverized and classified to obtain toner particles.

Toner particle material Binder resin Styrene acrylic resin (molecular weight Mn 0.35 × 10 ⁴ , glass transition point 57 ° C., glass transition point endothermic onset temperature 30 ° C.) 90% by weight wax Polypropylene wax 4% by weight Charge control agent 1 5% by weight Colorant Carbon black 5% by weight Thereafter, an external additive was added to the obtained toner particles as described below to produce a toner.

Method of Adding External Additive A predetermined amount of 4 kg of the particles obtained above and silica R976 manufactured by Nippon Aerosil Co., Ltd. were placed in the same plastic bag, and the whole plastic bag was shaken by hand to perform preliminary stirring.

Next, a Henschel mixer with a heating mechanism was prepared and stirred. FIG. 3 is a diagram illustrating an example of a stirring device used for manufacturing the developer of the present invention. This apparatus is a partially modified version of a Henschel mixer made by Mitsui Miike, and includes a stirring chamber 3 provided with stirring blades 4 and a stirring chamber 3
Introductory path 1 that is provided around the water and introduces hot water for heating
And a heating jacket 5 provided with a discharge path 2 for discharging hot water for heating. Further, in this apparatus, by applying a load with the stirring blade 4, the external additive fine particles can be more firmly attached to the toner particles.

Using this apparatus, first, hot water was passed through the introduction passage 1, and the internal temperature was stabilized until it reached a predetermined temperature. When the temperature reached a predetermined value, particles that had been preliminarily stirred were added.

The lid was closed, and the mixture was stirred at 1500 rpm for 5 minutes to prepare a sample. The equipment used for stirring is not limited to the Henschel mixer, but can be used by modifying it, such as a granulator or turbulizer.

Using the obtained toner, an image was formed with a copying machine manufactured by Toshiba, and the image and toner characteristics were confirmed and the storage characteristics were evaluated.

Evaluation Method of Storage and Storage Characteristics A predetermined amount of the toner to which the external additive was adhered by the above method was put in a plastic container and left in an atmosphere at 55 ° C. for 8 hours. Thereafter, the container was taken out, allowed to adjust to room temperature, and the toner was taken out and observed.も の indicates that no change was observed, Δ indicates that aggregation occurred but was easily loosened, and x indicates that it was not easily unraveled.

Evaluation of Developer Deterioration Level Evaluation was carried out using a Leo Dry 7550 copying machine manufactured by Toshiba. The obtained toner was put into a copying machine which was initialized after all replacements of consumables and the like, and a paper passing test was performed using a chart having a printing rate of 6% while supplying toner as needed.
The paper-passing test was performed by paying attention to the scattering of the toner generated in the machine due to the deterioration of the developer, and the point at which the scattered toner stained the inside of the evaluation device and eventually appeared in the image was defined as the deterioration point of the used toner.

If the point is 400,000 sheets or more,
A sample of 200,000 to 400,000 sheets was rated as Δ, and a sample of less than 200,000 sheets was rated X.

Evaluation of the degree of dispersion The mechanical strength of the toner produced by the above method when the toner particles were crushed under a load and a negative acceleration using a micro compression tester (MTC type manufactured by Shimadzu Corporation) was measured.
The approximate curve obtained by plotting the compressive displacement and the compressive strength at the time of 10% deformation is 11.094X-11.07 ≦ Y ≦ 3.
Those in the range of 0.161X-19.232 were evaluated as ○, and those outside this range were evaluated as ×.

Examples 1 to 6 and Comparative Examples 1 to 13 Samples were prepared and evaluated according to the above-described procedure while changing various toner preparation conditions, the amount of external additives added, and the temperature of the added atmosphere.

Table 1 below shows the preparation conditions and evaluation results of the samples.

[0045]

[Table 1]

As shown in Table 1, the developers of Examples 1 to 6 in which the external additive is within a predetermined temperature range and the displacement-strength curve at the time of compression satisfies a predetermined relational expression, In other cases, the characteristics were inferior.

[0047]

According to the present invention, it is possible to easily obtain a developer having good fluidity and dispersibility and having stable charging characteristics over the life.

When the developer of the present invention is used, an image having good image quality can be formed without causing toner scattering or the like.

[Brief description of the drawings]

FIG. 1 is a graph schematically showing a glass transition point endothermic onset temperature and a glass transition point temperature.

FIG. 2 is a graph showing a displacement-intensity curve during compression of toner particles.

FIG. 3 is a schematic view showing an example of a stirring device used for producing the developer of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Introductory path 2 ... Discharge path 3 ... Stirring chamber 4 ... Stirring blade 5 ... Heating jacket

Claims (4)

[Claims] 1. A toner particle containing a colorant and a binder resin, and an external additive adhered by heating and mixing to the toner particles in an atmosphere in a temperature range from the glass transition endothermic onset temperature to the glass transition point temperature of the binder resin. Agent and
The developer is characterized in that the toner particles have a displacement-intensity curve upon compression satisfying the following relational expression. 11.094X-11.07≤Y≤30.161X-1
9.323 (1.0 ≦ X ≦ 2.0) 2. The amount of the external additive added is 0.2 to 0.2.
2. The developer according to claim 1, wherein the amount is 1.0% by weight. 3. A step of forming toner particles containing a colorant and a binder resin, and adding an external additive to the toner particles in a temperature range from the glass transition endothermic onset temperature to the glass transition point temperature of the binder resin. Adhering by heating and mixing treatment, wherein the toner particles have a displacement-intensity curve upon compression satisfying the following relational expression: . 11.094X-11.07≤Y≤30.161X-1
9.323 (1.0 ≦ X ≦ 2.0) 4. The external additive may be added in an amount of 0.2 to 0.2.
The method for producing a developer according to claim 3, wherein the amount is 1.0% by weight.