JPH04121753A - Toner - Google Patents

Abstract

PURPOSE:To prevent the occurrence of void by introducing a fluorochemical compound being a lower surface energy material in a main structure of a binder resin. CONSTITUTION:The fluorinated polyester being the binder resin is obtained by using a fluorinated diol as an indispensable structural monomer of the polyester represented with formulae I, II, etc. Here Ra is CnH2n (0<=n<=3); Rb is CmH2m+1 (1<=m<=2); RF is CF3; and K is 0<=k<=1. For example as the binder resin, a fluorinated polyester as a coloring agent 5 wt. parts carbon black and 2 wt. parts a Cr containing azo dye are added, melted and kneaded with a pressure-kneader for 30 min. at 130 deg.C and a toner block is obtained. A cooled toner block becomes a coarse toner of about 2 mm particle size with a Rortplex crusher and subsequently the coarse toner is pulverized with a jet mill and the pulverized material is classified with an air classifier and the negative toner A of 5-20 mum of a particle size is obtained.

Description

[Detailed Description of the Invention] Summary] To provide a toner with excellent void resistance without impairing flash fixing properties and blocking resistance, regarding a toner used for developing electrostatic latent images such as in electrophotography. For this purpose, a toner using a binder resin is configured such that a fluorinated polyester is used as the binder resin, and a fluorine-containing polyol is used as a constituent monomer of the polyester.

[Industrial Application Field] The present invention relates to a toner used for developing electrostatic latent images such as electrophotography.

As an electrophotographic method, the method described in US Pat. No. 2,297,691 and the like is well known. This generally involves using a photoconductive insulator (such as a photocondrum), applying a -like electrostatic charge on the photoconductive insulator by corona discharge, etc., and applying various means to the photoconductive insulator. An electrostatic latent image is formed by irradiating the image with a light image, and then the latent image is developed and visualized using fine powder called toner. After transferring the toner image to paper etc. as necessary, pressure is applied. A copy is obtained by fixing a toner image on a recording medium such as paper by means such as heating, irradiation with a solvent, steam, or light.

[Prior Art] Toner for developing these electrostatic latent images has conventionally been prepared by dispersing a coloring agent such as carbon black in a binder resin made of natural or synthetic polymeric material, and using a toner having a thickness of about 5 to 20 μm. Finely ground particles are used.

Such toner is usually used alone or mixed with a carrier material such as iron powder or glass beads to develop an electrostatic latent image.

When toner is used alone for development (-component development method)
Toner usually contains magnetic powder, and the toner becomes frictionally charged when it rubs against members such as the wall of the developing device and the magnet roll in the developing device, and is further charged by the magnetic force of the magnet roll. As the magnetic roll rotates, the toner is carried to the latent image area on the photoconductive insulator, and development occurs when the charged toner adheres to the latent image due to electrical attraction.

In addition, when using a mixture of carrier and toner (two-component development method), the developer consisting of toner and carrier is triboelectrically charged by mixing and stirring in the developing device, and the toner is supported on the carrier. Development occurs when only the charged toner that is transported to the latent image area on the photoconductive insulator selectively adheres to the latent image due to electrical attraction. In this case as well, the toner image is formed only with toner.

In the case of two-component development, iron powder or other ferromagnetic particles are usually used as carriers, and in this case, the magnetic particles are held by a magnetic roll in the developing device to form a magnetic brush, and the magnetic particles form a magnetic brush. The rotation of the roll carries the magnetic brush to the latent image area on the photoconductive insulator, thereby transporting toner to the latent image area.

On the other hand, low polymer polymers generally called oligomers are often used as binder resins used in toners. Oligomers have low molecular weights, low melt viscosity, and good thermal stability, so they are widely used as binder resins for electrophotographic toners.

Further, the fixing is to melt the powder image of the toner and fix it to the recording paper, and the various methods described above are available for this purpose. Among these methods, flash fixing, which is a typical type of optical fixing, is a method in which fixing is performed using flash light from a discharge tube such as a xenon flash lamp, and has the following characteristics.

■Since it is non-contact fixing, image resolution during development will not deteriorate.

■There is no waiting time after the power is turned on, and a quick start is possible.

■Even if the recording paper gets stuck in the fuser due to system failure, it will not ignite.

■ Glued paper, preprinted paper, paper of different thickness, etc.
Fixation is possible regardless of the material or thickness of the recording paper.

The process by which toner adheres to recording paper by flash fixing is as follows.

As described above, when a toner image is transferred to recording paper, it adheres to the recording paper as a powder to form an image, and if rubbed with a finger, for example, the image will collapse. When a flash of light from a discharge tube such as a xenon flash lamp is applied to the toner, the toner absorbs the energy of the flash, its temperature rises, it softens and melts, and adheres to the recording. After the flash ends,
The temperature drops, solidifies, and the fixed image cries, completing the fixing.
A fixed image fixed on the recording paper will not disintegrate even if it is rubbed with a finger, for example.

What is important in flash fixing is that the toner melts and adheres firmly to the recording paper, and for this purpose, the toner absorbs light energy, including thermal energy that is dissipated into the outside world and does not contribute to temperature rise. It must absorb and melt sufficiently from the flash. Therefore, if the applied light energy is insufficient, the toner cannot be sufficiently melted and satisfactory fixing performance cannot be obtained. On the other hand, if the light energy is too strong, the viscosity of the toner decreases rapidly. At this time, when the surface tension acting on the toner overcomes the viscosity, the toner in the printed area aggregates and moves.As shown in Figure 1, white areas called voids 5 occur in the image, causing a decrease in image density. . Therefore, it is necessary that the toner 1 for flash fixing does not generate voids 5 due to movement of the toner 1.

In FIG. 1, 2 is a recording paper, 3 is a flash of light, and 4 is a fixed image.

Conventionally, as the binder resin for the flash fixing toner 1, epoxy resins such as bisphenol A diglycidyl ether polymer and polyester resins such as polyethylene terephthalate have been commonly used.

[Problems to be Solved by the Invention] However, in such conventional toners, when the above-mentioned resin is used as a binder resin, in order to obtain good fixing properties, it is necessary to use a low molecular weight resin with a relatively small molecular weight. It is necessary to use an oligomer with a melting point, but when such an oligomer is used, the melt viscosity is low, and when the toner is melted by flash light irradiation, the toner will aggregate due to the force of the toner to move due to surface tension. However, since the film was fused and solidified, voids in the image were unavoidable.

In order to prevent this, it is necessary to increase the melt viscosity of the binder resin to prevent the toner from moving and causing white spots. Methods to increase the melt viscosity include: ■ Increasing the degree of polymerization of the binder resin ■ Introducing relatively long side chains of 04 or more into the main chain structure of the binder resin ■ Introducing crosslinks between the main chain structures of the binder resin Possible methods include: However, methods ① and ③ can increase the melt viscosity but also increase the melting point, so although void generation can be prevented, the fixing performance is often impaired.
. Further, in method (2), the melt viscosity can be increased without increasing the melting point so much, but in this case, the glass transition point of the binder resin is lowered, so that blocking resistance is often extremely impaired.

The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a toner having excellent void resistance without impairing fixing properties and anti-blocking properties.

[Means for solving the problem] As a result of studies, the inventors introduced a fluorine-based compound, which is a low surface energy substance, into the skeletal structure of the binder resin as a method of reducing the surface tension of the binder resin when it is melted. It has been discovered that the occurrence of voids can be prevented by this, and the present invention has been completed.

That is, the present invention is a toner using a binder resin, in which a fluorinated polyester is used as the binder resin, and a fluorine-containing polyol is used as a constituent monomer of the polyester.

The present invention will be explained in more detail below.

The fluorinated polyester that is the binder resin in the present invention can be obtained by using, for example, fluorinated diols shown in structural formulas (1) to (6) as essential constituent monomers of the polyester.

Structural formula (4) %formula% Structural formula [6] HO-R,-(!nee R,-OH gate.

Here, R4 is C, Hs, (0≦n≦3), Rh is C-
Hs-0+ (1≦m≦2) RF, CFs, 0≦
To ≦! It is.

In addition, the monomer copolymerization ratio of the fluorinated monomer in the present invention is arbitrary, but it is 5 mo1% with respect to the total constituent monomers.
The above is desirable. This is because if the monomer copolymerization ratio is less than this, the effect of reducing surface tension is small and the ability to prevent voids is small.

Moreover, it is desirable that the molecular weight is 3500 to 1000G (in terms of polystyrene). This is because if the molecular weight is less than this, the melt viscosity of the binder becomes too small.
This is because even if the surface tension is reduced, it becomes difficult to prevent the generation of voids, and because the glass transition temperature is lowered, problems such as blocking are more likely to occur during toner storage. Further, when the molecular weight exceeds 100 (IQ), the melting point of the binder becomes high, which deteriorates the fixability of the toner.

It is also possible to use the fluorinated polyester of the present invention by appropriately mixing it with other binders suitable for flash fixing, such as bisphenol A type epoxy resin, polyester resin, and polyamide resin.

Note that the toner used in the present invention can be manufactured by a conventionally known method. That is, binder resin, colorant,
And if necessary, inorganic fillers, charge control agents, etc. are kneaded, melted, and uniformly dispersed using a pressure kneader, roll mill, extruder, etc., pulverized using a pulverizer such as a jet mill, and then pulverized using a classifier such as a wind classifier. The desired toner can be obtained by classification.

[Examples] Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto.

Example binder resins include terephthalic acid, isophthalic acid, trimethic acid, neopentyl glycol, polyoxypropylene (2,2) -2,2-bis(4-hydroxyphenyl)propane, polyoxyethylene (2,2) -
2,2-bis(4-hydroxyphenyl) -1,1,
Fluorinated polyester containing 3,3-tetrafluoropropane as a constituent monomer, 5 parts by weight of carbon black (Black Pearls L; manufactured by Cabot Corporation) as a coloring agent, 2 parts by weight of chromium-containing azo dye (Bontron 5-34; manufactured by Orient Chemical Co., Ltd.) 130°C and 30°C using a pressure kneader.
The mixture was melted and kneaded to obtain a toner mass. The cooled toner mass was processed into a coarse toner having a particle size of approximately 2IIm using a rotoplex mill.

Next, the coarse toner is finely pulverized using a jet mill (PJM pulverizer; manufactured by Nippon Pneumatic Industries), and the pulverized product is classified using an air classifier (manufactured by Albine Co., Ltd.) to obtain particles with a particle size of 5 to 5.
A negative polarity toner of 20 μm was obtained.

In addition, polyoxyethylene (2,2)-2,2-bis(4), which is the fluorine-containing monomer of the fluorinated polyester,
-Hydroxyphenyl)-1゜1.3.3 The mole percent of tetrafluoropropane is 15%, and its surface tension is 2
It was 18 dyes/cm at 00°C.

In addition, magnetite powder coated with styrene resin as a carrier (average particle size 110 μm; manufactured by Kanto Denka)
FAC uses 95 parts by weight and adds 5 parts by weight of toner A to prepare a developer and adopts the flash fixing method.
A printing test and a fixing test were conducted using a modified OM-6715D laser printer (using an organic photoreceptor).

At this time, the thickness of the toner on the paper was set to 10 to 15 μm. The setting conditions for the fixing device were such that a capacitor with a capacitance of 160 μF was used, and the charging voltage was 2150 V. This was applied to the flash lamp to cause the flash lamp to emit light, thereby fixing the image onto the paper. In addition, to evaluate the fixability, adhesive tape (Scotch Mending Tape, manufactured by 3M Co., Ltd.) was lightly applied, and an iron cylindrical block with a diameter of 100 ra 11 and a thickness of 2 (111111) was placed on recording paper at a constant speed in the circumferential direction. After adhering to the tape, the tape was peeled off, and the ratio of the optical density after peeling to the optical density of the image before peeling the tape was expressed as a percentage to evaluate the fixing performance.The optical density was measured using a Macbeth PCM meter. This was done by

As a result of the fixing test, the fixing rate to the toner was 90%, indicating excellent fixing properties. Furthermore, there are very few voids in the fixed image, and the optical density of the image is 0. D.

It showed a high blackness of 1.1.

Comparative Examples The monomers constituting the polyesters described in Examples were changed from polyoxyethylene (2,2)-2,2-bis(4-hydroxyphenyl)-1,1,3,3tetrafluoropropane to polyoxyethylene (2,21 A polyester resin was synthesized in the same manner as in the example except that -2,2-bis(4-hydroxyphenyl)propane was used, and its surface tension was 25 dlne/ctn at 200°C.

Toner B was prepared using this binder resin in the same manner as in the example and evaluated in the same manner as in the example. As a result of the fixing test, the fixing rate of toner B was 80%, indicating relatively good fixing. However, there were many voids in the fixed image.
Image optical density 0.0. =0.8.

[Effects of the Invention] As described above, according to the present invention, a toner with excellent void resistance can be obtained without impairing fixing properties and anti-blocking properties.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of void generation. In the figure, 1... Toner 2...recording paper, 3...Flash, 4...Fixed image, 5...Void.

Claims (1)

[Claims] A toner using a binder resin, characterized in that a fluorinated polyester is used as the binder resin, and a fluorine-containing polyol is used as a constituent monomer of the polyester.