JP2007271732A - Nonmagnetic single component toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nonmagnetic single component toner that prevents contamination on a charging roll and has an excellent improving effect on fog, uneven picture quality and followup ability. <P>SOLUTION: The toner is obtained by externally adding titanium oxide particles in an additive amount of 1.0 mass% or lower to toner base particles containing a binder resin and a colorant, the titanium oxide particles having a particle size of 100 nm or smaller and having hydrophobicity imparted by a silicone oil treatment. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a non-magnetic one-component toner, and more particularly to a non-magnetic one-component toner obtained by externally adding titanium oxide particles.

  Conventionally, nonmagnetic one-component toners are known in which inorganic particles such as silica particles and titanium oxide particles are externally added to improve various properties. For example, by adding titanium oxide particles, which are less likely to cause electrostatic aggregation than silica particles, to the toner particles, stable fluidity can be obtained, thereby charging the toner uniformly and uniformly in image formation. It is possible to form a toner layer. In addition, by subjecting the titanium oxide particles to a hydrophobic treatment, it is possible to protect the titanium oxide particles that are generally highly hygroscopic from the influence of environmental fluctuations.

Also, in a low-temperature and low-humidity environment, the silica fine powder alone is partially overcharged, causing problems that the toner charge distribution becomes non-uniform or the toner layer is not uniformly formed due to electrostatic aggregation. By adding hydrophobized titanium oxide particles together with silica particles, it becomes possible to impart fluidity to the toner while suppressing electrostatic factors, and the toner is uniformly charged and the toner layer is uniformly formed. It is also known that this is possible (see Patent Document 1).
JP 2005-049630 A

  However, the toner described in the above-mentioned patent document has a wide particle size of titanium oxide particles of 35 to 500 nm, a large addition amount of 0.01 to 3% by mass, and the hydrophobization treatment is performed by silane coupling rather than silicone oil. When the titanium oxide particles hydrophobized in this way are externally added to the toner particles, the charging roll stain is not sufficiently improved, and fog, image quality unevenness, and followability are not improved. However, an excellent effect is not always obtained.

  An object of the present invention is to provide a non-magnetic one-component toner which is made under such circumstances and prevents the charging roll from being stained, and always has an excellent improvement effect in terms of fog, image quality unevenness, and followability. To do.

  In order to solve the above problems, the present invention provides 1.0% by mass of titanium oxide particles having a particle diameter of 100 nm or less and hydrophobized by silicone oil treatment on a toner particle matrix containing a binder resin and a colorant. Provided is a nonmagnetic one-component toner which is externally added in the following addition amount.

  In the nonmagnetic one-component toner of the present invention, the titanium oxide is preferably anatase type. Silica particles can be externally added together with the titanium oxide particles.

  According to the present invention, by adding a small amount of titanium oxide particles hydrophobized by a silicone oil treatment to toner particles with a low addition amount, the charging roll is prevented from being soiled, fogging, image quality unevenness, and tracking. As a result, it is possible to obtain a non-magnetic one-component toner that always has an excellent improvement effect.

  The best mode for carrying out the invention will be described below with reference to the drawings.

  In the electrophotographic toner according to an embodiment of the present invention, small-sized titanium oxide particles hydrophobized by a silicone oil treatment are externally added in a low addition amount to a toner particle base containing a binder resin and a colorant. It is characterized by.

  The present inventors can obtain various advantages such as obtaining stable fluidity by externally adding the titanium oxide particles hydrophobized to the toner particle matrix, but such advantages are always obtained. However, it has been found that it is difficult to improve, particularly, the charging roll dirt. As a result of repeated experiments focusing on the particle size and the addition amount of the titanium oxide particles, it has been found that the effect of the external addition of the titanium oxide particles greatly depends on the particle size and the addition amount of the titanium oxide particles. It was.

  FIG. 1 shows an overview of such findings.

  That is, the amount of added titanium oxide particles and the particle size were changed in various ways to examine fog, image quality unevenness, followability, and charging roll contamination, and the amount of added titanium oxide particles was plotted on the horizontal axis and the particle size on the vertical axis. As a result of plotting the coordinates, the results shown in FIG. 1 were obtained. In the graph of FIG. 1, ◯ indicates that fog, image quality unevenness, followability, and charging roll stain are improved, and x indicates that fog, image quality unevenness, followability, and charge roll stain are deteriorated.

  As can be seen from FIG. 1, when the addition amount of the titanium oxide particles is small and the particle size is small, the effect of improving the charging roll contamination is obtained.

  From the results shown in FIG. 1, the amount of titanium oxide particles added externally is 1.0% by mass or less, preferably 0.5 to 1.0% by mass, based on the whole toner. When the addition amount of the titanium oxide particles exceeds 1.0% by mass, for example, at 1.5% by mass or more, fogging, uneven image quality, followability, and charging roll contamination tend to deteriorate.

  The particle size of the titanium oxide particles to be externally added is 100 nm or less, preferably 50 to 100 nm. When the particle size of the titanium oxide particles exceeds 100 nm, for example, when the particle size is 200 nm or more, fogging, uneven image quality, followability, and charging roll contamination tend to deteriorate.

  Therefore, in FIG. 1, the area surrounded by the circle is the effective area, and it is understood that when the titanium oxide particles having a small particle diameter are externally added with a low addition amount, excellent effects, in particular, charging roll contamination is improved. .

  The externally added titanium oxide particles must be hydrophobized with silicone oil. The present inventors have found that charging roll stains cannot be improved by hydrophobizing with a silane coupling agent, and charging roll stains can be improved only after hydrophobizing with silicone oil. It was.

  As the silicone oil, dimethyl silicone oil, methylphenyl silicone oil, methyl hydrogen silicone oil, amino-modified silicone oil, carboxyl-modified silicone oil, alkyl-modified silicone oil, fluorine-modified silicone oil and the like can be used.

  The treatment amount of the silicone oil is preferably 0.5 to 3.0% by mass with respect to the amount of titanium oxide particles. When the treatment amount of the silicone oil is less than 0.5% by mass, the charging roll stain is deteriorated, and when it exceeds 5.0% by mass, aggregation tends to occur.

The added titanium oxide may be a rutile type or anatase type, but the anatase type can be preferably used.
In addition to titanium oxide particles, silica particles may be externally added. The addition amount of silica particles is preferably about 0.1 to 4.0% by mass of the whole toner. It is desirable that the silica particles are also hydrophobized.

  The nonmagnetic one-component toner according to one embodiment of the present invention is manufactured as follows.

  First, a toner material containing a binder resin and a colorant is mixed by 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.

  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 from the kneader is usually cooled, pulverized, and classified to a predetermined particle size according to the method used for producing the toner to obtain a toner particle matrix. 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 airflow can be used for cooling, an airflow pulverizer such as a collision plate pulverizer can be used for pulverization, and various airflow classifiers can be used for classification. it can.

  By adding titanium oxide particles hydrophobized with silicone oil to the toner particle matrix thus obtained, and mixing and stirring, a non-magnetic one-component toner can be obtained.

  The binder resin that can be used for the non-magnetic one-component toner according to the embodiment of the present invention described above 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.

  The nonmagnetic one-component toner according to an embodiment of the present invention can include a charge control agent and a release agent in addition to the binder resin, the colorant, and the titanium oxide particles hydrophobized with silicone oil. As the charge control agent and the release agent, any of those usually used for electrophotographic toners can be used.

  Examples of the present invention and comparative examples will be described below.

Example 100 parts by weight of a polyester resin (manufactured by Kao Corporation, Tg: 63 ° C., Tm: 144 ° C.), 1 part by weight of a charge control agent “LR-147” (manufactured by Nippon Carlit), colorant ECB-101, ECG -405 (manufactured by Dainichi Seika Co., Ltd.) and a release agent “Carnauba wax” were premixed with a Henschel mixer.

  The obtained raw material mixture was supplied to an open roll type continuous kneader (trade name: Kneedex, manufactured by Mitsui Mining Co., Ltd.) and continuously kneaded, and the kneaded material was cut with a roll cutter on the discharge side of the kneader, A continuous strip-shaped kneaded product having a width of 10 mm and a thickness of 3 mm was obtained. The kneaded product was cooled with a blower so as to cool to 70 ° C. or less within 10 seconds.

  Next, the belt-shaped kneaded product is pulverized with a feather mill (FM-1, manufactured by Hosokawa Micron Corporation), and further pulverized with a collision plate pulverizer (IDS-2, manufactured by Nippon Pneumatic Co., Ltd.), and then an airflow classifier. Classification was performed with DSX-2 (manufactured by Nippon Pneumatic) to obtain colored fine particles having a weight average particle diameter of about 6 μm.

  Silica and titanium oxide fine powder were mixed and stirred into the colored fine particles thus obtained with a mixer equipped with standard blades as mixing blades to obtain a non-magnetic one-component toner. As silica fine particles, RY50 (manufactured by Aerosil) and TG810G (manufactured by Cabot) were used, and the addition amounts thereof were RY50: 2 mass% and TG810G: 0.3 mass%. In addition, as the titanium oxide fine particles, those with and without silicone oil treatment with various particle sizes and addition amounts were used.

  The thus obtained non-magnetic one-component toner was tested for fogging, image quality unevenness, followability, and charging roll stain, and each was evaluated. The test method is as follows.

Test 1-Fog A toner is mounted on a non-magnetic one-component developing device "Casio Page Prest N-5" (Casio Computer Co., Ltd .: color printer 29 sheets per minute (A4 landscape feed), process speed 129 mm / sec). In an environment (25 ° C, 50% RH), after printing 10,000 sheets of 5% print images continuously using plain paper (XEROX-P paper A4 size), printing on blank paper, Printing is forcibly terminated by opening the door, and the fog toner on the OPC drum at that time is copied onto a mending tape and affixed to a blank sheet, and compared with a tape from which fog toner has not been collected.

  For the measurement, the maximum value of the difference before and after the fogging is determined as the fog value from the XYZ value obtained using a spectroscopic color difference meter “SE-2000” (manufactured by Nippon Denshoku Co., Ltd.), and evaluated according to the following criteria.

◎: Very good when fog value is less than 2 ○: Good when fog value is 2 or more and less than 5 △: Level where fog value is 5 or more and less than 10 and has no practical problem ×: Bad when fog value is 10 or more Non-uniform one-component developing device “Casio Page Presto N-5” (manufactured by Casio Computer Co., Ltd .: color printer 29 sheets per minute (A4 landscape feed machine, process speed 129 mm / sec)) After printing 10,000 sheets of 5% printed images using plain paper (XEROX-P paper A4 size) at 50 ° C. and 50% RH), A4 solid images are printed and image evaluation is performed according to the following criteria. .

◎: No image deterioration ○: Some unevenness occurs (level of no problem in practical use)
×: Generation of unevenness as the image is reversed Test 3-Followability Non-magnetic one-component developing device “Casio Page Presto N-5” (manufactured by Casio Computer Co., Ltd .: 29 printers per minute (A4 landscape feed) machine, process speed 129 mm / sec), and after continuously printing 10,000 sheets of 5% print images using plain paper (XEROX-P paper A4 size) in a normal environment (25 ° C., 50% RH), A3 A solid image is printed and image evaluation is performed according to the following criteria.

◎: No image deterioration ○: Some unevenness occurs (level of no problem in practical use)
X: Unevenness occurs in image Test 4-Charging roll contamination Non-magnetic one-component developing device “Casiopage Presto N-5” (manufactured by Casio Computer Co., Ltd .: color printer 29 sheets per minute (A4 lateral feed), process speed 129 mm / sec), and after continuously printing 10,000 sheets of 5% printed images using plain paper (XEROX-P paper A4 size) in a normal environment (23 ° C., 50% RH) Observe the surface dirt visually.

  In the evaluation of the above test, image deterioration due to the charging roll stain is confirmed, and the stain on the charging roll is confirmed.

◎: No charging roll contamination ○: Image does not appear but charging roll contamination ×: Charging roll contamination enough to appear in image (1) Obtained by changing the particle size of titanium oxide particles in various ways The above test was conducted on the nonmagnetic one-component toner. The results are shown in Table 1 below.

  From Table 1 above, the toners according to Examples 1 and 2 to which titanium oxide having a particle diameter of 100 nm or less was externally added exhibited excellent performance in terms of fogging, uneven image quality, followability, and charging roll stains. However, the toners according to Comparative Examples 1 and 2 to which titanium oxide having a particle diameter exceeding 100 nm is externally added are good in terms of fog, but inferior in all of image quality unevenness, followability, and charging roll stain. I understand that.

(2) The above test was performed on non-magnetic one-component toners obtained by varying the amount of titanium oxide added. The results are shown in Table 2 below.

  From Table 2 above, all of the toners according to Examples 3 and 4 to which titanium oxide was externally added at an addition amount of 1.0% by mass or less were excellent in terms of fog, image quality unevenness, followability, and charging roll stain. Although the toners according to Comparative Examples 3 and 4 to which titanium oxide was externally added in an addition amount exceeding 1.0% by mass showed good fog, uneven image quality and followability, the charging roll It turns out that it is inferior about dirt.

(3) The above test was conducted on a non-magnetic one-component toner externally added with oil-treated titanium oxide and non-oil-treated titanium oxide. The results are shown in Table 3 below.

  From Table 3 above, all of the toners according to Examples 5 to 7 with externally added oil-treated titanium oxide showed excellent performance in terms of fogging, uneven image quality, followability, and charging roll dirt. It can be seen that the toner according to Comparative Example 5 to which titanium oxide that has not been oil-treated is externally added is good in image quality unevenness and followability, but is slightly inferior in fog and inferior in charging roll contamination.

The characteristic view which shows the influence of the fogging by the addition amount and particle size of a titanium oxide particle, image quality unevenness, follow-up property, and charging roll dirt.

Claims (3)

  Externally adding titanium oxide particles having a particle diameter of 100 nm or less and hydrophobized by silicone oil treatment to an amount of 1.0 mass% or less to a toner particle matrix containing a binder resin and a colorant. A non-magnetic one-component toner.   The non-magnetic one-component toner according to claim 1, wherein the titanium oxide is an anatase type.   The nonmagnetic one-component toner according to claim 1, wherein silica particles are externally added together with the titanium oxide particles.

Images