JPH0762764B2 - Thermal fixing type electrostatic image developing toner - Google Patents

Description

The present invention relates to an electrostatic charge image developing toner used for developing an electrostatic charge image formed on the surface of an image carrier. The present invention relates to an improved toner for developing a heat fixing type electrostatic image.

[Conventional technology]

In an electrophotographic method used as an output form of an information processing apparatus, an electrostatic charge image formed on the surface of an image carrier is developed by a magnetic brush made of a developer containing toner, and then transferred to a recording medium such as plain paper. However, it is generally fixed by heat or pressure means. The developer used in the electrophotographic method is supplied to the developing device in a constant amount and then continuously replenished while being appropriately replenished in accordance with the decrease in the amount used, so that the quality does not vary throughout the period of use. That is, preservation is required. In addition, as the fixing means using a heating means such as a heat roll, it is desirable that the fixing can be performed at a lower temperature from the viewpoint of power saving.

[Problems to be solved by the invention]

In the developing toner using the above-mentioned heat fixing means (especially oilless type), in order to improve the fixing property, that is, when the molecular weight of the thermoplastic resin constituting the toner is reduced so that the fixing can be performed at a low temperature, However, the glass transition temperature of the toner is lowered and the storability of the toner is lowered, which is inconvenient. On the other hand, if storability is emphasized, the above-mentioned molecular weight increases and the fixing temperature rises, causing not only energy loss but also
This is an inconvenience because it shortens the life of the heat roll and hinders the speeding up of the equipment. In addition, it is not preferable to add a large amount of hydrophobic colloidal silica for improving the storage stability, because the image carrier is scratched and the moisture resistance is deteriorated. That is, the fixability and the storability are reciprocal to each other, and the conventional toner has a problem in that they cannot be improved at the same time.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems existing in the prior art, and to provide a toner for developing a heat fixing electrostatic image which has a high level of fixability and storability.

[Means for solving problems]

In order to solve the above problems, in the present invention, in a heat fixing type charge image developing toner containing at least a resin and a colorant, 0.1 to 5.0 parts by weight of a fine granular resin powder having a glass transition temperature of 50 ° C. or more on the toner surface. %, And the melt viscosity at 150 ° C was kept below 10 ⁴ poise.

[Action]

If the melt viscosity of the toner is lowered, it has the effect of lowering the fixing temperature, that is, it is effective for improving the fixing property, but if it remains as it is, it causes a blocking phenomenon and extremely reduces the storage stability. Thus, the melt viscosity at 150 ° C is 10 ⁴ po.
A toner having an ise or less (preferably 5 × 10 ³ poise or less) causes the blocking phenomenon described above and cannot be used at all in the past. However, by adhering the fine-grained resin powder having a glass transition temperature of 50 ° C. or higher to the surface of the toner, the aggregation action of the toners is prevented and the blocking resistance is improved.

If the glass transition temperature of the fine particulate resin powder attached to the toner surface is less than 50 ° C, the action of preventing the aggregation of the toner particles cannot be expected. In addition, as a resin constituting the above powder, an acrylic resin, an acrylic-vinyl monomer copolymer, and the like are preferable. Further, if the average particle diameter of the fine resin powder is less than 0.1 μm, the effect of preventing the aggregation of the toner particles cannot be expected even if they are attached to the toner surface.
On the other hand, if it exceeds 1.0 μm, it cannot adhere to the surface of the toner particles, which is inconvenient. The fine resin powder is
It is contained in an amount of 0.1 to 5.0% by weight, but if it is less than 0.1% by weight, the amount adhering to the surface of the toner particles is small, so that the effect of preventing mutual binding or aggregation of the toner particles is insufficient.
If it exceeds 0% by weight, excess free fine-grained resin powder intervenes to reduce the charging stability of the toner, which is inconvenient.

As the resin that can be used as the developing toner of the present invention,
Known thermoplastic resins such as styrene type, styrene-acrylic type, styrene-butadiene type, polyester type and epoxy type can be used. The toner may contain carbon black or other colorants or pigments, and if necessary, a positive or negative charge control layer or magnetic powder such as magnetite. Further, in order to improve the offset resistance, a relatively low molecular weight polypropylene, polyethylene wax or the like may be contained. Further, colloidal silica or the like can be externally added as a fluidity modifier of the toner.

〔Example〕

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

(Toner A) 84 parts by weight of styrene-acrylic resin (SBM73F made by Sanyo Kasei) 5 parts by weight of polypropylene (Viscole 550P made by Sanyo Kasei) 10 parts by weight of carbon black (# 44 made by Mitsubishi Kasei) 1 part by weight of negative charge control agent (Orient Chemically manufactured Bontron E81) The above blended materials were dry-mixed and kneaded with a kneader at a temperature of 200 ° C. The resulting mixture was cooled and solidified, and then pulverized by a jet mill into particles of 20 μm or less. Next, after introducing this pulverized powder into a hot air stream at 120 ° C to perform heat treatment,
The toner was classified through a zigzag classifier to obtain a toner having a particle size distribution of 5 to 20 μm.

Next, in a four-necked flask equipped with a stirrer, a thermometer, a nitrogen inlet tube, and a reflux condenser, methyl methacrylate 100 was added.
Parts, 300 parts of distilled water, and a redox catalyst consisting of potassium persulfate and sodium thiosulfate as an initiator 5 ×
It was added so as to be 10 ^-3 mole / l, and the reaction was carried out at 60 ° C for 2 hours in a nitrogen stream. After that, the liquid temperature was cooled to 20 ° C, and an average particle size of 0.4 μm and Tg5 was measured using an ultrafiltration device and a hot air dryer.
A fine powder of PMMA (polymethylmethacrylate) at 3 ° C was prepared. 0.5 parts by weight of this fine powder and the above toner were mixed with a Henschel mixer to prepare a toner A having PMMA fine powder adhered to the toner surface. Thus, the melt viscosity of Toner A was 5 × 10 ³ poise.

To measure the melt viscosity of the toner, a Shimadzu flow tester was used, and a 0.5 mmΦ × 10 mm die was used.
A load of 0 kg was applied and measurement was performed under the condition of a temperature rising rate of 6 ° C./min.

(Toner B) Toner B (melt viscosity at 150 ° C. 5 × 10 ³ pois) under the same conditions as Toner A except that polyester resin (KTR2150 manufactured by Kao Corporation) was used as the resin and PMMA was 1.0 part by weight.
e) created.

[Comparative example]

(Toner C) Under the same conditions as the toner A, toner C does not contain PMMA fine particles. (Toner D) Toner D was prepared under the same conditions as in Toner B, except that 0.5% by weight of PMMA / PBMA (poly-n-butylmethacrylate copolymer) was contained as fine particulate resin powder having a glass transition temperature of 48 ° C.

The toners A to D and the carrier (KBN-100 manufactured by Hitachi Metals) are mixed to form a developer having a toner concentration of 5%, and a commercially available copying machine (U-bix-3000 manufactured by Konishi Roku Photo Co., Ltd.) is used. The results of image evaluation are shown in the table.

The triboelectric charge amount of each toner in the table is a value measured with a commercially available blow-off powder charge amount measuring device (TB-200 manufactured by Toshiba Chemical) under the following conditions. 10 g of carrier (KBN100 made by Hitachi Metals) and 0.5 g of toner are put into a plastic container with an outer diameter of 40 mm, and the mixture is rotated for 10 minutes with a flow surface angle measuring device, and a 200 mg sample is taken from the obtained mixture, The charge amount was measured by the above-mentioned charge amount measuring device under the conditions of a blow pressure of 1.0 kg / cm ² and a blow time of 40 seconds. In the table, normal humidity and high humidity are values measured at 25 ° C relative humidity 40% and 25 ° C relative humidity 85%, respectively.

As is apparent from the table, since the toner C does not contain the fine-grained resin powder, the toners cause a phenomenon in which the toners are combined or aggregated, and the storage stability is poor. Further, since the above powder is not contained, the glass transition temperature of the toner as a whole is low, and the cleaning property is slightly inferior. Toner D, which contains fine-grained resin powder, has a low glass transition temperature and thus has a slightly poor storability. Toners A and B for these
In addition to the fixability, the storage stability is good. Further, the toners A and B have good cleaning properties, that is, the toner remaining on the surface of the photoconductor drum after transfer is very well removed. It is presumed that this is because the fine resin powder adhered to the surface of the toner particles has a function of preventing non-electrostatic bonding with the surface of the photoconductor drum as well as preventing bonding between the toner particles. It

〔The invention's effect〕

Since the toner for heat-developing electrostatic image development of the present invention has the structure and operation as described above, not only the fixability but also the storage stability can be greatly improved, and the image after transfer can be greatly improved. There is an effect that the cleaning property when removing the residual toner from the carrier can be improved.

Claims (4)

[Claims] 1. A heat-fixing type electrostatic image developing toner containing at least a resin and a colorant, wherein 0.1 to 5.0% by weight of a fine granular resin powder having a glass transition temperature of 50 ° C. or more on the toner surface.
And the melt viscosity at 150 ℃ was 10 ⁴ poise.
A heat-fixing type electrostatic charge image developing toner characterized by the following. 2. The average particle diameter of the fine granular resin powder is 0.1 to 1.0 μm.
The heat fixing type electrostatic image developing toner according to claim 1, wherein 3. The heat fixing type electrostatic image developing toner according to claim 1, wherein the fine granular resin powder is made of an acrylic resin. 4. The fine particle resin powder as claimed in claim 1, which is an acrylic-vinyl monomer copolymer.
Item 6. A heat-fixing type electrostatic image developing toner according to item.