JPH04121752A - Toner - Google Patents

Abstract

PURPOSE:To obtain a toner excellent in a void-proof characteristic without damaging a fixing property and an antiblocking property by using a specified salt of perfluoroalkyl carbonic acid as a surface tension reducing agent in a beinder resin. CONSTITUTION:The fluorine type surface active agent used for the surface tension reducing agent may be added either at a stage which the binder resin is polymerized from the monomer or at a stage which the toner structural material is melted and kneaded. For example as the binder resin, 92 wt. parts an epoxy resin is used and as the surface tension reducing agent 0.5 wt. parts K salt of perfluoroalkyl carbonic acid, 5 wt. parts carbon black as a coloring agent and 3 wt. parts a Cr type azo dye are added, melted and kneaded with a pressure-kneader for 30 min. at 130 deg.C and a toner block is obtd. A cooled toner block is becomes a course toner having about 2 mm particle size with a Rortplex crusher. Subsequently the course toner is pulverized with a jet mill and the pulverized product is classified with an air classifier and a negative charge toner A having 5-20 mum a particle size is obtained. As the result of printing test, the toner A is excellent in a void-proof characteristic and the printing density is 1.1 and the surface tension of the toner A is 13 dyne/cm.

Description

[Detailed Description of the Invention] [Summary] To provide a toner that is used for developing electrostatic latent images such as electrophotography and has excellent void resistance without impairing fixing properties and anti-blocking properties. In a toner using a binder resin, a perfluoroalkyl carboxylate represented by the following general formula is used as a surface tension reducing agent in the binder resin.

[Industrial Application Field] The present invention relates to a toner used for developing electrostatic latent images in electrophotography and the like.

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 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.

[Problem to be Solved by the Invention 1] 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 aggregates due to the shear force that causes 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, at least a toner that has been dispersed with a substance that reduces the surface tension or the intermolecular force that acts between the molecules that make up the binder resin, that is, a surface tension reducing agent, is used 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 perfluoroalkyl carboxylate represented by the above general formula 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.

As the polymer used for the surface tension reducing agent, a perfluoroalkyl carboxylate having a hydrophilic group and a hydrophobic group and represented by the following general formula can be used. R, , R2 bonded to carbon constituting the main chain of the surface tension reducing agent are mainly composed of F, but some R,, R2 may be H.

Here, the surface tension can be controlled by the ratio of H and F, and the amount of charge of the toner can also be controlled by the negative chargeability of F.

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 at the binder resin polymerization stage, the surface tension reducing agent does not thermally decompose even at the synthesis temperature of the binder resin, does not inhibit the polymerization of the binder resin, or does not induce side reactions. limited to.

The amount of the surface tension reducing agent used in the present invention is determined based on the material of the surface tension reducing agent and the surface tension of the binder resin.
e/cm or less, which is 0.0 relative to the toner weight.
1 to 2, corresponding to QQvt%.

The reason why the amount of fluorosurfactant added must be 2.00v1% or less is that if it is more than this, the melt viscosity will become too low due to the melt viscosity reduction effect of the surface tension reducing agent, and the void prevention ability will decrease. This is because you end up doing it. Also, 0. [The reason why it has to be 1 IvlX or more is because if it is less than this, the effect of void prevention ability due to surface tension reduction cannot be expected.

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 weight 900-1000
) 92 parts by weight, 0.5 parts by weight of perfluoroalkylcarboxylic acid potassium salt (manufactured by Sumitomo 3M Co., Ltd.) as a surface tension reducing agent, and carbon black (Black Pearls; average particle size) as a coloring agent. 0.
024μm1 specific surface area 138rrf/g; manufactured by Cabot Corporation) 5 parts by weight, chromium-based azo dye (Oil Black B
3 parts by weight (Y, manufactured by Orient Chemical Co., Ltd.) were added and melted and kneaded for 30 minutes at 130° 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 about 211 IIl 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 negatively charged toner A of 20 μm was obtained.

Next, 5 parts by weight of toner A, amorphous iron powder T as a carrier,
A developer consisting of 95 parts by weight of SV100/200 (manufactured by Nippon Steel Powder) was prepared, a printing test was conducted using a modified FACOM-6715D laser printer, and 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 using a surface tension measuring device (Digiomatic ESB-V,
@Kyowa Kagakusha) at 200°C.

As a result of the printing test, Toner A had excellent void resistance, and the printing density was 1.1. The surface tension of toner A was 13 dyne/cm (see the attached table). Example 2 As a binder resin, polyester (polyethylene terephthalate, weight Using 92 parts by weight (average molecular weight: 1000), 5 parts by weight of carbon black as a coloring agent and 3 parts by weight of a lyromium azo dye were added, and the mixture was melt-kneaded at 130° C. for 30 minutes 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 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 the printing density was 1.3. The surface tension of toner B was 10d7ne/cm (see attached table) Example 3 62 parts by weight of styrene acrylic to which 2.0 parts by weight of potassium perfluoroalkylcarboxylate was added based on the weight of the resin as a binder resin. , using 30 parts by weight of polyester resin (polyethylene terephthalate, weight average molecular weight + 000) to which no fluorosurfactant is added,
Furthermore, 3 parts by weight of carbon black (Black Pearls L) and 3 parts by weight of chromium-based azo dye were added as colorants, and the mixture was melt-kneaded at 130° C. for 30 minutes 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 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. The surface tension of toner C was 9d7ne/cm (see attached table) 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. Ta.

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 0.8. Further, the surface tension of the toner D is 25d
7ne/cm (see attached table).

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. Also, the surface tension of toner E is 23d7
ne/co+ (see attached table).

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 a fluorosurfactant was used as a surface tension reducing agent.

As a result of performing print evaluation and surface tension measurement using the same method as in Example 1, it was found that the print of this toner had a large number of voids and the print density was 0.7. Also, the surface tension of toner F is 9
d7ne/cll (see attached table).

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. Also, the surface tension of toner G is 33d7
ne/cm (see attached table).

Attached Table Evaluation Results of Prototype Toner [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, ■・・・Toner 2...recording paper, 3...Flash, 4...Fixed image, 5...Void.

Claims (1)

[Scope of Claims] A toner using a binder resin, characterized in that a perfluoroalkyl carboxylate represented by the following general formula is used as a surface tension reducing agent in the binder resin. ▲There are mathematical formulas, chemical formulas, tables, etc.▼R_1, R_2:F
(However, some of R_1 and R_2 can be H.) R_3: H or cation