TWI598711B - Toner composition and preparing method thereof - Google Patents

Description

Imaging composition and preparation method thereof

The present invention relates to a developing composition and a method for preparing the same, and more particularly to an image forming composition which is improved by the external additive to enhance the charging stability of the developing particles.

With the development and popularization of computers and peripheral devices, photocopiers and laser printers have become one of the common printing equipment.

The imaging method of the photocopier and the laser printer mainly comprises the following steps: (1) a power-discharging step, which is the first step of the imaging method, which is uniformly distributed on the photosensitive drum having no surface charge; 2) In the writing step, since the photosensitive drum is an insulator before illumination, after being illuminated, it is converted into a conductor. Therefore, after the photosensitive drum is illuminated, the electric charge existing on the surface will be converted into a conductor by the photosensitive drum, and the electric charge is derived, so that it is illuminated by light. The area to be reached will have an "electrostatic latent image"; (3) the imaging step, that is, using the principle of triboelectric generation or charge injection, so that the surface of the toner is electrostatically charged, and then the bias is applied to transfer the toner to the existing On the photosensitive drum of the electrostatic latent image, the purpose of development is achieved; (4) a transfer step of applying an electric field between the photosensitive drum and the rotating roller to transfer the toner onto the paper; and (5) a melting step, through the heating Or pressure to fix the toner to the paper.

According to the above imaging method, for toner, in imaging In the step, the development of the electrostatic latent image has a very close relationship with the amount of toner charged. Therefore, if the frictional charge of the toner changes, or the charging characteristics of the toner are unstable, the printing quality is deteriorated, and the quality of the image is obtained. Have a great impact.

However, at present, the preparation method of the carbon powder can be roughly divided into a chemical method and a physical method. Please refer to FIG. 1(a), and FIG. 1(a) is a schematic diagram of the appearance of the carbon powder prepared by the chemical method, and is prepared by a chemical method. The carbon powder has a relatively uniform shape and has a high roundness of about 0.951, so that the charging characteristics and the transfer rate are good. In addition, the current industry uses the pulverization method to produce carbon powder, and the shape of the carbon powder prepared by the industry is mostly irregular, the particle size is large and the particle size distribution is wide, as shown in Fig. 1(b). The roundness is about 0.929. Therefore, in the developing step, when the static electricity is generated on the surface of the carbon powder by the rubbing method, the contact area between the carbon powder or the carbon powder and the carrier is low, so the charge amount on the surface of the carbon powder is also It is lower; or, when static electricity is generated when the charge is injected on the surface of the carbon powder, the problem of uneven charging due to the structure of the carbon powder causes a poor transfer rate.

However, when the carbon powder is prepared by a chemical method, a large amount of waste reaction solution is generated, which is liable to cause environmental pollution, and the preparation cost is high. Therefore, in order to achieve lower cost and environmental protection, it is preferable to adopt a physical method. The carbon powder is prepared by a pulverization method.

In order to overcome the defects in the charging characteristics of the irregularly shaped carbon powder prepared by the physical pulverization method, a novel carbon powder improvement method is urgently needed to improve the charging property of the pulverized carbon powder and improve the pulverized carbon powder rotation. Write effect and print quality of toner.

The main object of the present invention is to provide a developing composition which can improve the printing quality of a long time printing by using an external additive to improve the stability of the toner charge amount.

The imaging composition provided by the present invention comprises: a developing particle comprising a binder resin, a coloring agent, a release agent, and a charge control agent, wherein the circularity of the imaging particle is 0.95 or less; and an external additive present on the surface of the developer particle, wherein the external additive comprises at least one metal oxide particle.

The image-forming particles as described above are prepared by a pulverization method comprising a mixture of the binder resin, the colorant, the release agent, and the charge control agent, preferably by a pulverization method. Prepared by jet milling. Since the developing particles are prepared by a pulverization method and their shapes are irregular, the circularity is 0.95 or less, or even 0.93 or less. The content of the binder resin is preferably 40 to 60% by weight, and the content of the colorant is preferably 35 to 50% by weight, based on the total weight of the image forming particles; The content of the release agent may preferably be 0.3 to 3 weight percent; and the content of the charge control agent may preferably be 0.1 to 2 weight percent, but the content of the above components is not particularly limited in the present invention.

In the developing composition of the present invention, the binder resin to be used is not particularly limited and may be any binder resin known in the art. For example, the resin may be at least one selected from the group consisting of styrene-acrylic copolymer resins, polyester resins, styrene-butadiene copolymer resins, and mixtures thereof. However, in the present invention, the binder resin is preferably benzene. Ethylene-acrylic copolymer resin, and the weight of the binder resin is 40 to 60% by weight based on the weight of the developer particles.

Further, in the developing composition of the present invention, the releasing agent to be used is not particularly limited and may be any one of the release agents conventionally known in the art. For example, it may be wax, low molecular weight polyethylene, low molecular weight polypropylene, fatty acid metal salt, fatty acid ester, higher fatty acid having a carbon number of at least 17, fatty acid guanamine or a mixture thereof to facilitate separation of the developer and The photosensitive element also enhances the effect of the developer. However, in the present invention, the release agent used is preferably a wax such as PE wax, PP wax, rice wax or palm wax, and the release agent is preferably contained in terms of the weight of the developer particles. It is 0.3 to 3 weight percent.

In the developing composition, the coloring agent to be used is not particularly limited and may be any coloring agent known in the art and is selected depending on the desired color tone. For example, a black developer composition may be prepared using carbon black or magnet powder as a colorant for use in a black and white photocopier; or, other color tone dyes may be used to prepare a color developer, and applied to a color print. In the watch machine. In the developing composition of the present invention, the coloring agent used is a magnet powder, and the coloring agent is preferably contained in an amount of 35 to 50% by weight based on the weight of the developing particles.

Further, in the developing composition of the present invention, the charge controlling agent to be used is not particularly limited, and it may be any conventionally applicable charge controlling agent such as a metal tyros compound, a quaternary ammonium salt, or aniline black. In the present invention, the charge control agent used is preferably aniline black, and the charge control agent is preferably contained in an amount of 0.1 to 2% by weight based on the weight of the developer particles.

In the developing composition of the present invention, the external additive includes at least the metal oxide particles, and the external additive is present on the surface of the developing particles. The metal oxide particles as the external additive in the present invention comprise at least iron oxide particles, and the iron oxide particles are preferably Fe ₂ O ₃ ‧FeO. In addition, the content of the iron oxide particles may be 0.5 to 3 weight% of the total weight of the image forming particles, and preferably the content may be 1 to 2.5 weight% of the total weight of the image forming particles, and more preferably the content may be the developing particles. 1 to 2 weight percent of the total weight. When the iron oxide particles are added as an additive other than the developing particles and are present on the surface of the developing composition particles, the charging characteristics of the developing composition can be stabilized in the developing step. In addition, the metal oxide particles as the external additive may further include at least one selected from the group consisting of cerium oxide particles, titanium oxide particles, and alumina particles, and when the external additive includes iron oxide particles and at least one selected When the group consisting of free cerium oxide particles, titanium oxide particles, and alumina particles, the content is 1 to 4% by weight, preferably 2 to 4% by weight based on the total mass of the developing composition.

Furthermore, the development composition provided by the present invention may be a non-magnetic imaging composition or a magnetic imaging composition. When the imaging composition provided by the present invention is a magnetic imaging composition, the developing particles may further comprise a magnetic particle, and the magnetic particle may be a magnetic particle known in the art, such as iron oxide or tetraoxide. iron.

When magnetic particles are added to the developing composition, the developing composition has magnetic properties and is a magnetic developing composition. The imaging step during imaging may be "non-contact", and the "non-contact" imaging step means that there is a gap between the photosensitive drum and the developing roller, and the magnetic imaging composition is magnetically And by the jumping method, the developing roller is transferred to the photosensitive drum, which is called Make a "jumping image".

In the developing composition provided by the present invention, the developing particles and the external additive are uniformly mixed such that the external additive is uniformly distributed on the surface of the developing particles. And the additives existing on the surface of the developing particles can change the charging characteristics of the developing particles having a circularity of 0.95 or less, or even 0.93 or less, and stabilize the electricity of the developing composition when the developing step is performed. Sex, which can increase the transfer rate, thus reducing the waste rate when printing. Further, when the developing particles provided by the present invention contain magnetic particles and serve as a magnetic developing composition, the external additive can also increase its magnetic properties.

The invention further provides a method for preparing a developing composition, comprising: (A) mixing a binder resin, a coloring agent, a releasing agent, and a charge controlling agent to form a first mixture; (B) The first mixture is subjected to a chain mixing step and a grinding step to obtain a plurality of imaging particles, wherein the imaging particles have a circularity of 0.95 or less; and (C) mixing the imaging particles and a An external additive to obtain a developing composition, wherein the external additive is present on a surface of the developing particle, and the external additive comprises at least one metal oxide particle.

In the present invention, according to the above preparation method, in the step (A), the first mixture may further comprise a magnetic particle, and the magnetic particle may be a magnetic particle known in the art, such as iron oxide or tetraoxide. iron. When a magnetic particle is included in the first mixture in the step (A), the developing composition prepared by the above preparation method is a magnetic developing composition, and the developing mechanism is as described above.

Further, the step (A) of the preparation method provided by the present invention The content of the binder resin, the colorant, the release agent, the charge control agent, and the magnetic particles contained in the first mixture is as described above, and thus will not be described again.

Further, according to the above preparation method, in the step (B), the kneading step is carried out by a conventional kneading method in the art. And the grinding step may be a pulverization method to obtain a plurality of developing particles, and preferably by a jet milling method to perform the grinding step, since the developing particles are prepared by a pulverization method, and the shape thereof is less Rules, so its roundness is below 0.95, even below 0.93.

Further, in the step (C) of the production method provided by the present invention, the metal oxide particles are at least one iron oxide particle, and the iron oxide particles may be particles composed of Fe ₂ O ₃ ‧FeO. The iron oxide particles may be from 0.5 to 3 weight percent, and preferably from 1 to 2.5 weight percent, more preferably from 1 to 2 weight percent, based on the total weight of the developer particles. Further, in the step (C), the metal oxide particles may further comprise at least one selected from the group consisting of cerium oxide particles, titanium oxide particles, and alumina particles. When the external additive comprises iron oxide particles, and at least one selected from the group consisting of cerium oxide particles, titanium oxide particles, and aluminum oxide particles, the external additive is 1 to 4 weight percent of the total weight of the developing particles. Preferably, it is preferably 2 to 4% by weight.

In the step (C), the process of mixing the developing particles and the external additive is to place an appropriate amount of the developing particles and the external additive in a mixer to uniformly mix and make the outer The additive is uniformly distributed on the surface of the developing particles.

In the present invention, the term "roundness" means the radial offset of the actual contour of the toner particles with respect to the ideal circle, that is, the difference between the maximum radius and the minimum radius of the same center. .

Fig. 1(a) is a schematic view showing the appearance of a carbon powder prepared by a chemical method.

Fig. 1(b) is a schematic view showing the appearance of a carbon powder prepared by a pulverization method.

2 to 3 are schematic views showing the method of Test Example 2 of the present invention.

Example 1

51.6% by weight of styrene-acrylic acid copolymer, 46% by weight of magnetic iron powder, 2% by weight of low molecular weight polypropylene (release agent), and 0.4% by weight of quaternary ammonium salt (charge control agent) The mixture is prepared into a semi-finished product of a developer by a process such as kneading, milling, and grading. The external additive used in this example mainly consists of 1.0% by weight of cerium oxide, 0.3% by weight of titanium oxide, 0.1% by weight of aluminum oxide, and 1.0% by weight of iron oxide. Next, the developer semi-finished product of the present embodiment and the external additive were uniformly mixed to form a developing composition. Among them, the roundness of the developer semi-finished product of this example was 0.929 using FPIA-3000 (Sysmex corporation) measurement.

Example 2

The developer semi-finished product used in this comparative example was the same as in Example 1, and the external additive was mainly composed of 1.0% by weight of cerium oxide and 0.3 weight. A percentage by weight of titanium oxide, 0.1% by weight of alumina, and 2.0% by weight of iron oxide. The developer semi-finished product and the external additive are uniformly mixed to form a developing composition.

Comparative example 1

The developer semi-finished product used in this comparative example was the same as in Example 1, and the external additive was mainly composed of 1.0% by weight of cerium oxide, 0.3% by weight of titanium oxide, and 0.1% by weight of alumina. The developer semi-finished product and the external additive are uniformly mixed to form a developing composition.

Test example 1

This test example uses the Trek Model 210HS to measure the electrical properties of the development compositions prepared in the above examples and comparative examples by loading the imaging composition into a printer and printing them during the printing process. After blank test page, directly measure the toner electrical properties on the developing roller. The results are shown in Table 1. When the electrical properties were more than 25 μC/g, good print quality was obtained.

Test example 2

This test example tests the transfer ratios of the development compositions prepared in the above examples and test examples for use in a printer, and the test results are shown in Table 2. The conversion rate is calculated as (1-B/A) × 100%, where A is the weight of the toner consumed, and B is the weight of the waste powder.

When printing, the imaging composition that has not been transferred to the paper is removed into the waste toner tank via the cleaning blade. The higher the transfer rate, the less waste toner is produced. If the transfer rate is lower than 80%, it is easy. The waste toner tank overflows and the powder is damaged, which affects the printing quality.

Test Example 3

In this test example, the development compositions prepared in the above examples and comparative examples were measured for the whiteness at the time of printing by the printer. In this test example, the reflectance was measured using a Photovolt Model 577 Reflectometer to estimate the whiteness. As shown in FIG. 2, first, a paper 11 is provided, and a post-it® is attached to the center of the paper. A blank page is printed on the paper 11, and the reflectance of six points from 1 to 6 in the figure is measured in sequence, and the average value is A. After removing the post-it note, the five points in Figure 3 are averaged and the value is B. The difference between A and B is the whiteness value. The results of the test are shown in Table 3, wherein the smaller the whiteness value, the better the print quality.

Test Example 4

This test example measures the ID value of the imaging composition prepared by using the above examples and comparative examples, and is measured by a concentration agent (DensiEye-700 (X-rite)). The estimated print quantity is calculated by (full-card powder loading/single-spraying amount), and the measured ID value and estimated printing amount are shown in Table 4.

From the results of the above test examples, it can be known that the addition of the external additive can improve the charge stability of the development composition, and at the same time improve the transfer rate of the imaging composition, and can maintain the printing for a long time. quality.

The above-mentioned embodiments are merely examples for convenience of description, and the scope of the claims is intended to be limited to the above embodiments.

Claims (6)

An imaging composition comprising: a developing particle comprising a binder resin, a coloring agent, a release agent, and a charge control agent, wherein the imaging particles have a circularity of 0.95 or less; An external additive is present on the surface of the imaging particle, wherein the external additive comprises iron oxide particles, cerium oxide particles, titanium oxide particles, and an aluminum oxide particle, wherein the iron oxide particle is Fe ₂ O ₃ ‧FeO, and the content of the iron oxide particles is 0.5 to 3 weight percent based on the total weight of the developer particles. The developing composition according to claim 1, wherein the developing particles are prepared by a pulverization method. The imaging composition of claim 1, wherein the external additive is present in an amount of from 1 to 4% by weight based on the total weight of the imaging composition. A method for preparing a developing composition, comprising: (A) mixing a binder resin, a coloring agent, a release agent, and a charge control agent to form a first mixture; (B) sequentially ordering the first The mixture is subjected to a chain mixing step and a grinding step to obtain a plurality of imaging particles, wherein the imaging particles have a circularity of 0.95 or less; and (C) mixing the imaging particles and an external additive to obtain An imaging composition, wherein the external additive is present on a surface of the image forming particle, and the external additive comprises iron oxide particles, cerium oxide particles, titanium oxide particles, and an aluminum oxide particle, wherein The iron oxide particles are Fe ₂ O ₃ ‧FeO, and the content of the iron oxide particles is 0.5 to 3 weight percent based on the total weight of the developing particles. As in the method of claim 4, in the step (B), the grinding step is carried out by a pulverization method. The method of claim 4, wherein in step (C), the external additive is from 1 to 4% by weight based on the total weight of the developer particles.