JPH04147268A - Toner - Google Patents

Abstract

PURPOSE:To enhance void resistance without impairing toner fixability and its blocking resistance by adding a fluorinated surfactant. CONSTITUTION:This toner contains in a binder resin as a surface tension reduc ing agent the fluorinated surfactant, such as fluoroalkyl quaternary ammonium salt, represented by formula I in which each of R1 - R3 is F optionally containing partially H; each of R'1 - R'3 is alkyl or aryl; and An<-> is an anion. This binder resin can be embodied by epoxy resins, polyester resins, and the like.

Description

[Detailed Description of the Invention] U Summary J To provide a toner with excellent void resistance without impairing fixing properties and anti-blocking properties, with respect to a toner used for developing electrostatic latent images such as in electrophotography. In a toner using a binder resin, a fluorosurfactant is used as a surface tension reducing agent in the binder resin.

INDUSTRIAL APPLICATION FIELD OF THE INVENTION The present invention relates to toners used for developing electrostatic latent images such as in 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 mixed and stirred in the developing device and is triboelectrically charged, 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, the resolution of the image during development does 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 and solidifies, becoming a fixed image and 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 emits 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 the 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 Problems] As a result of studies, the inventors found that in order to prevent a decrease in fixing properties due to an increase in the melting point of the binder resin or a decrease in blocking resistance due to a decrease in the glass transition point, the inventors conducted a comparison of melt viscosity. Even when using a binder resin with a low surface tension, use a toner that has at least a substance that reduces surface tension or the intermolecular force that acts between the molecules that make up the binder resin, that is, a surface tension reducing agent dispersed therein to reduce the surface tension. The present inventors have discovered that the occurrence of voids due to aggregation can be suppressed by this, and have accomplished the present invention.

That is, the present invention uses a fluorine-based surfactant as a surface tension reducing agent in the binder resin in a toner using a binder resin.

The present invention will be explained in more detail below.

The polymer used as the surface tension reducing agent may be any fluorine-based surfactant that has a hydrophilic group and a hydrophobic group and exhibits surface activity, such as a fluoroalkyl quaternary ammonium salt represented by the following general formula: Rl + Rs , Rs :F
(However, some of Rt, Rri, and Rs can be H) Rlo
, R,', R,': alkyl group or aryol group An
-: Anion etc. can be used.

The fluorosurfactant used as the surface tension reducing agent may be added at the stage of polymerizing the binder resin from the monomer, or at the stage of melting and kneading the toner constituent materials. However, when adding a surface tension reducing agent during the polymerization stage of the binder resin, it is limited to materials in which the surface tension reducing agent does not thermally decompose even at the synthesis temperature of the binder resin, inhibits the polymerization of the binder resin, or induces side reactions. It will be done.

The amount of the surface tension reducing agent used in the present invention is determined based on the material and the surface tension of the binder resin, but polyester resin (polyethylene terephthalate)
In the case of 1! at 200℃! M7ne/cm or less is preferable, and this corresponds to a surface tension reducing content of 0.01 to 2.00 wt% based on the weight of the toner. The reason why the amount of fluorosurfactant added must be Q,01vj% or more is that if it is less than this, the effect of void prevention ability due to surface tension reduction cannot be expected. Also, 2.
The reason why it must be kept at 00 wj% or less is that if it is more than this, the effect of reducing melt viscosity will be stronger than the effect of reducing surface tension by the surface tension reducing agent, and as a result, the void prevention ability will decrease. It's for a reason.

The toner binder used in the present invention may be any resin used in electrophotography, and for example, styrene acrylic, epoxy resin, polyester resin, etc. can be used alone or in combination. When using a binder resin in which a surface tension reducing agent is dispersed in combination with other binder resins,
As long as the required amount of surface tension reducing agent is added as a whole, a resin to which the surface tension reducing agent is added to only one binder resin may be used.

The toner used in the present invention can be manufactured by a conventionally known method. That is, a binder resin, a colorant, a surface tension reducing agent, and if necessary carbon, a charge control agent, etc. are melt-kneaded and uniformly dispersed using, for example, a pressure kneader, roll mill, extruder, etc., and then dispersed uniformly using, for example, a jet mill or the like. The desired toner can be obtained by pulverizing the toner and classifying it using a classifier, for example, a wind classifier.

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

Example 1 Epoxy resin (bisphenol A) was used as the binder resin.
diglycidyl ether, epoxy equivalent 900-+000
) 92 parts by weight, 0.5 parts by weight of perfluoroalkyl quaternary ammonium iodide (manufactured by Sumitomo 3M) as a surface tension reducing agent, and carbon black (Black Pearls L; Average particle size: 0.024 μm 1 specific surface area: 138 rrf/g; manufactured by Cabot Co., Ltd.) 5 parts by weight, chromium dye (Bondron 5
-34. 3 parts by weight of Orient Chemical Source) were added and melt-kneaded for 30 minutes at +3[1°C] using a pressure kneader to obtain a toner mass. The cooled toner mass was made into a coarse toner having a particle size of 2 mm using a Rotoplex mill.

Next, the coarse toner was finely pulverized using a jet mill (PJM pulverizer, manufactured by Nippon Pneumatic Industries), and the pulverized product was classified using a wind rough classifier (manufactured by Alpine) to obtain a particle size of 5.
A negatively charged toner A of ~20 μm was obtained. Toner A5 parts by weight, unshaped iron powder TSY100/200 (
A developer consisting of 95 parts by weight (Japanese iron powder type) was prepared and FA
A printing test was conducted using a modified COM-6715D laser printer. Attached Table 1 shows the changes to the laser printer. The optical density of the image was measured using a Macbeth PCM meter. Note that the occurrence of voids was visually observed.

The surface tension of toner A was measured at 200°C using a surface tension measuring device (Digiomatic ESB-1, Kyowa Kagakusha).
Measured at.

As a result of the printing test, Toner A had excellent void resistance, and the printing density was 1.2. Further, the surface tension of toner A was 12 dyne/cm (see Appendix 2).

Example 2 As a binder resin, 92 parts by weight of polyester (polyethylene terephthalate, weight average molecular weight 10θ0) to which 10 parts by weight of perfluoroalkyl quaternary ammonium iodide (manufactured by Sumitomo 3M) was added based on the weight of the resin was used, and Add 5 parts by weight of carbon black and 3 parts by weight of chromium dye as a coloring agent, and pressurize the mixture to 1.
The mixture was melt-kneaded at 30° C. for 30 minutes to obtain a toner mass. The cooled toner mass is crushed into a particle size of 2mm using a rotoplex pulverizer.
The coarse toner was

Next, the coarse toner is finely pulverized using a jet mill, and the pulverized product is classified using an air classifier to obtain a particle size of 5 to 20 μm.
Negatively charged toner B was obtained.

As a result of printing evaluation, Toner B had excellent void resistance and print density was 1.2. Further, the surface tension of toner B was 9 dYne/cm (see Appendix 2).

Example 3 As a binder resin, 62 parts by weight of styrene acrylic to which 20 parts by weight of perfluoroalkyl quaternary ammonium iodide was added based on the weight of the resin, and a polyester resin (polyethylene terephthalate, by weight) to which no fluorine surfactant was added. Using 30 parts by weight (average molecular weight 1000), 3 parts by weight of carbon black (Black Pearls L) and 3 parts by weight of chromium dye were added as colorants, and the mixture was melt-kneaded at 130°C for 30 minutes using a pressure kneader to form a toner mass. Obtained.

The cooled toner mass was made into a coarse toner having a particle size of 2 mm using a rotoplex mill.

Next, the coarse toner was pulverized using a jet mill (PJM pulverizer), and the pulverized product was classified using an air classifier (manufactured by Alpine) to obtain negatively charged toner C having a particle size of 5 to 20 μm.

As a result of printing evaluation, Toner C was found to have excellent void resistance and a printing density of 1.3. Further, the surface tension of Toner C was 8 dyne/cm (see Appendix 2).

Comparative Example 1 Toner D was obtained in the same manner as in Example 1, except that no surface tension reducing agent was added during toner melt-kneading. As a result of a printing test and surface tension measurement conducted using the same method as in Example 1, it was found that the printing of this toner had many voids and the printing density was 0.
．． It was 8. Moreover, the surface tension of the toner D is 25dy
ne/cm (see Appendix 2).

Comparative Example 2 Toner E was obtained in the same manner as in Example 2, except that a fluorosurfactant as a surface tension reducing agent was not added to the binder resin. As a result of performing a printing test and surface tension measurement using the same method as in Example 1, it was found that the printing of this toner had many voids and the printing density was 0.7. Further, the surface tension of Toner E was 23d7ne/cm (see Appendix 2).

Comparative Example 3 Using 92 parts by weight of epoxy resin as the binder resin,
On the other hand, toner F was obtained in the same manner as in Example 1, except that 3 parts by weight of the fluorosurfactant was used including the surface tension reducing agent. As a result of printing evaluation and surface tension measurement performed using the same method as in Example 1, it was found that the printing of this toner had a large number of voids and the printing density was 07. Further, the surface tension of Toner F was 7 dyne/cm (see Appendix 2).

Comparative Example 4 Toner G was obtained in the same manner as in Example 2, except that no fluorine-based surfactant was added as a surface tension reducing agent to the styrene acrylic. As a result of performing a printing test and surface tension measurement using the same method as in Example 1, it was found that the printing of this toner had many voids and the printing density was 0.6. In addition, the surface tension of Toner G was 33d7nc/cm (see Attached Table 2) Attached Table 2 Evaluation Results of Prototype Toner [Effects of the Invention] As explained above, according to the present invention, fixing performance and blocking resistance were improved. A toner with excellent void resistance can be obtained without impairing properties.

[Brief explanation of the drawing]

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 fluorine-based surfactant is used as a surface tension reducing agent in the binder resin.