JPH06258865A - Toner for two component type developer containing no charge controlling agent - Google Patents

Abstract

PURPOSE:To provide the toner for two component type developer which is not incorporated with a charge controlling agent, capable of reducing the cost, stabilizes the picture density even in copying many sheets, good in transfer efficiency and capable of preventing toner from being scattered. CONSTITUTION:The toner for two component type developer is incorporated with a magnetic material in a ratio of 1-10wt.pts.per 100 wt.pts. binding resin in place of the charge controlling agent, and the large grain size particles having 0. 05-1mum average grain size is added in a ratio of 0.05-5wt.pts.per 100 wt.pts. toner particles, the charge controlling agent is not incorporated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel two-component developer toner containing no charge control agent, and more specifically, it utilizes a so-called electrophotographic method such as an electrostatic copying machine or a laser beam printer. The present invention relates to a two-component developer toner containing no charge control agent, which is preferably used in an image forming apparatus.

[0002]

2. Description of the Related Art In an image forming apparatus using electrophotography, first, the surface of a photoconductor is exposed to form an electrostatic latent image on the surface of the photoconductor. Next, a developer is brought into contact with the surface of the photoconductor by a developing device. Then, the toner contained in the developer adheres to the electrostatic latent image, and the electrostatic latent image is visualized as a toner image. When this toner image is transferred from the surface of the photoconductor to the surface of the paper and fixed, an image corresponding to the electrostatic latent image is completed.

As the developer, a two-component type developer composed of the above toner and a carrier mainly containing magnetic particles such as iron powder and ferrite particles is generally used. The carrier has a function of applying an electric charge to the toner by frictional charging, and at the same time, supplying the toner to the electrostatic latent image with the toner adsorbed on the surface. A toner used for a two-component developer is generally prepared by mixing a binder resin with a colorant (for example, carbon), a charge control agent, a release agent (for example, wax) and the like. Of these, the charge control agent is used for the purpose of controlling the triboelectric charge amount of the toner that governs development and transfer, and its selection is the most important in designing the toner. Such charge control agents include an electron donating substance and an electron withdrawing substance, which charge the toner positively and negatively, respectively.

However, there are some charge control agents conventionally used that contain heavy metals such as chromium-containing dyes. When such a charge control agent is used,
Harm is a problem. Further, when a charge control agent having a nitro group in the molecule is used, the ignition property becomes a problem.

Further, since the charge control agent has a very high unit price as compared with the binder resin and other additives, there is a problem that the unit price of the toner becomes high despite the content rate of about several percent. On the other hand, since the charge control agent is involved in the triboelectric chargeability of the toner, if the charge control agent is simply excluded from the toner components, the image density decreases as the number of copies increases, as shown by A in FIG. There is a drawback that. This is because, as shown in FIG. 4, the electrostatic charge between the toner and the carrier increases due to the increase in the charge amount of the toner as the number of copies increases, and the toner is less likely to separate from the carrier. . On the other hand, the normal toner containing the charge control agent has a stable charge amount and a constant image density (shown by B in FIGS. 3 and 4).

Further, the toner containing no charge control agent has drawbacks that the transfer efficiency is lowered and the toner is easily scattered. The transfer efficiency decreases because the charge amount of toner increases as the number of copies increases. Further, it is considered that the cause of the toner scattering is that the toner containing no charge control agent has a low charge amount at the initial stage of copying as shown in FIG.

A main object of the present invention is to stabilize the image density and transfer efficiency, maintain a high image density and transfer efficiency, and prevent toner scattering, for a two-component developer containing no charge control agent. To provide toner. Another object of the present invention is to provide a toner for a two-component developer which does not contain a charge control agent and therefore can reduce material cost.

[0008]

The toner of the present invention is used for a two-component developer and contains a magnetic material in an amount of 0.1 parts by weight per 100 parts by weight of a binder resin.
10 to 10 parts by weight, and a large particle size powder having an average particle size of 0.05 to 1 μm was added to the surface in a ratio of 0.05 to 5 parts by weight with respect to 100 parts by weight of the toner particles. , Does not contain a charge control agent.

That is, as a result of intensive studies conducted by the present inventors to provide a toner for a two-component developer containing no charge control agent, the magnetic material is contained in the above proportion in place of the charge control agent. At this time, the present invention was completed by obtaining new knowledge that the charge amount of the toner is stable, as a result, the image density is improved, and the toner scattering is significantly reduced. Further, addition of the magnetic material to the toner also contributes to improvement of transfer efficiency.

The inclusion of a magnetic material in the toner is
Although well known as a magnetic toner, the magnetic toner is used for a one-component developer that does not use a carrier, and the compounding ratio of the magnetic material is usually 20 to 80 parts by weight, which is a large amount. Different from the inventive toner. That is, in the present invention, when the content of the magnetic material exceeds 10 parts by weight, the electric resistance of the developer increases and the image density decreases, which is not preferable. On the other hand, when the content of the magnetic material is less than 0.1 part by weight, the effect of stabilizing the toner by the magnetic material cannot be expected.

Further, in the present invention, in addition to containing the magnetic material, the average particle diameter is 0.0 on the surface of the toner particles.
The transfer efficiency and the image density are further improved by adding the powder having a large particle size of 5 to 1 μm at a ratio of 0.05 to 5 parts by weight to 100 parts by weight of the toner particles. The reason why the transfer efficiency is improved will be described below with reference to FIGS. 1 and 2. First, when a toner containing no charge control agent is used, the transfer efficiency decreases because the charge amount of the toner increases as the number of copies increases. That is, as shown in FIG. 2, the transfer of the toner particles 11 to the paper 10 is performed by the electrostatic force (indicated by the arrow a) that transfers the toner to the paper by corona discharge from the back side of the paper 10. However, since the electrostatic force is superior to the image force (shown by an arrow b) and the Van der Waals force (shown by an arrow c) on the photoconductor 12 that attracts the toner particles 11 to the photoconductor 12, It is considered that the transferability from the photoconductor 12 of No. 11 to the paper 10 becomes poor. That is, when the charge amount increases above a certain amount,
This is because the image force and the van der Waals force related to the toner charge become large.

On the other hand, as shown in FIG. 1, when the large particle size powder 14 is added to the surface of the toner particles 13, when the toner particles 13 are transferred from the photoreceptor 12 to the paper 10,
A gap s is formed between the photoconductor 12 and the toner particles 13, and the contact area between them is reduced. In this state, the image force e and the van der Waals force f are smaller than the electrostatic force d due to the corona discharge, so that the toner particles 13 are easily transferred to the paper 10 and the transfer efficiency is improved.

By the way, conventionally, for the purpose of improving the fluidity and cleaning properties of toner particles, as an external additive, colloidal silica in the form of fine powder having a particle size (primary particle size) of about 0.01 to 0.03 μm. , Alumina, titanium oxide, etc. are added to the surface of toner particles. However, with such an external additive having a small particle diameter, the gap s between the photoconductor 12 and the toner particle 13 is small, so that the contact area between the toner particle and the photoconductor is not sufficiently reduced, and therefore the transfer efficiency is improved. Has almost no effect on However, in the present invention,
In order to improve fluidity and the like, such an external additive having a small particle size may be used together with a powder having a large particle size.

The two-component developer toner of the present invention will be described in more detail below. The toner of the present invention is formed by blending a pigment and a release agent together with the magnetic material in the binder resin. As the binder resin, any conventionally used one can be used, such as polystyrene,
Chloropolystyrene, poly-α-methylstyrene, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene-maleic acid copolymer, styrene- Acrylic ester copolymer (eg styrene-
Methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-phenyl acrylate copolymer, etc.), styrene-methacrylic acid ester Copolymers (for example, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-phenyl methacrylate copolymer, etc.),
Styrene-α-chloromethyl acrylate copolymers, styrene resins such as styrene-acrylonitrile-acrylic acid ester copolymers (for example, styrene or mono- or copolymers containing styrene substitutes), vinyl chloride resins, styrene -Vinyl acetate copolymer, rosin-modified maleic acid resin, phenyl resin, epoxy resin, polyester resin, low molecular weight polyethylene, low molecular weight polypropylene, ionomer resin, polyurethane resin, silicone resin, ketone resin, ethylene-ethyl acrylate copolymer, Examples thereof include xylene resin and polyvinyl butyral resin. These resins may be used alone or in combination of two or more.

Of these, it is particularly preferable to use a styrene resin and a styrene-acrylic resin. The magnetic material may be magnetite, for example.
(Fe ₃ O ₄ ), various ferrites, maghemite (γ-Fe
₂ O ₃ ), CrO ₂ , magnetic powder such as iron alloy powder.
Examples of the ferrites include iron oxide zinc oxide (ZnFe
₂ O ₄ ), yttrium iron oxide (Y ₃ Fe ₅ O ₁₂ ), cadmium iron oxide (CdFe ₂ O ₄ ), gadolinium iron oxide (Gd ₃ Fe ₅ O ₁₂ ), copper oxide (CuFe ₂ O ₄ ), oxidation Iron lead (PbFe ₁₂ O ₁₂ ), iron nickel oxide (NiFe ₂ O ₄ ), iron neodymium oxide (NdFeO ₃ ), iron oxide barium (BaFe ₁₂ O ₁₉ ), iron magnesium oxide (MgFe ₂ O ₄ ),
Examples thereof include ferrite particles made of one or more of iron manganese oxide (MnFe ₂ O ₄ ), lanthanum iron oxide (laFeO ₃ ), and the like. These magnetic materials have an average particle size of 0.05 to 5μ.
It is preferably m.

The electric resistance of the magnetic material may be high or low, and generally has a volume resistance of 1 ×.
10 ^-1 to 1 × 10 ⁹ Ω · cm, preferably 1 × 10 ¹ to 1
A material of × 10 ⁶ Ω · cm is used. For the above reason, the magnetic material is added in an amount of 0.1 to 10 parts by weight, preferably 0.3 to 7 parts by weight, based on 100 parts by weight of the binder resin.

The colorant to be incorporated in the binder resin is
For example, carbon black, lamp black, chrome yellow, hansa yellow, benzidine yellow, bethlen yellow, quinoline yellow, permanent orange G
TR, Pyrazolone Orange, Pulcan Orange, Watching Red, Permanent Red, Brilliant Carmine 3B, Brilliant Carmine 6B, DuPont Oil Rend, Pyrazolone Red, Resor Red, Rhodamine B Lake, Lake Red C, Rose Bengal, Aniline Blue, Ultramarine Blue, Chalco Oil Blue, Methylene Blue Chloride, Phthalocyanine Blue, Phthalocyanine Green, Malachite Green, etc., or CISolvent Yellow 60, CISolvent Red 2
7, oil-soluble dyes such as CISolvent Blue 35. These colorants may be used alone or in admixture of two or more.

These colorants are added in an amount of 1 to 30 parts by weight, preferably 2 to 20 parts by weight, based on 100 parts by weight of the binder resin. Examples of the release agent (anti-offset agent) include aliphatic hydrocarbons, aliphatic metal salts, higher fatty acids,
Examples thereof include fatty acid esters or saponified products thereof, silicone oil, and various waxes. Of these, aliphatic hydrocarbons having a weight average molecular weight of about 1,000 to 10,000 are preferable. Specifically, one or a combination of two or more of low molecular weight polypropylene, low molecular weight polyethylene, paraffin wax, a low molecular weight olefin polymer composed of olefin units having 4 or more carbon atoms, silicone oil and the like is suitable.

The release agent is added in an amount of 0.1 to 10 parts by weight, preferably 0.5 to 8 parts by weight, based on 100 parts by weight of the binder resin. Toner is manufactured by kneading, crushing,
It can be carried out by a dry method by sieving or a wet method by spray granulation in the form of a dispersion liquid, and the produced toner is adjusted to a preferable particle size range by a classification operation such as air classification. The particle size of the toner is not particularly limited and may be in a commonly used range, but is generally 5 to 20 μm, preferably 6 to 12 μm.

The material of the large particle size powder added to the surface of the toner particles is not particularly limited, and various kinds of inorganic powder such as metal powder and resin powder can be used. Examples of the inorganic powder include magnetic powder such as magnetite, iron powder, aluminum powder, silica powder, alumina powder, and titanium oxide powder. As the resin powder, for example, acrylic resin, polyester resin,
Examples of the powder include polyurethane resin and silicone resin.

The particle size of the large particle size powder which is the surface treatment agent is 0.05 to 1 μm in average particle size, more preferably 0.
It is suitable that it is about 07 to 1 μm. The addition amount of the large particle size powder is 0.0 with respect to 100 parts by weight of the toner particles.
It is suitable that the amount is 5 to 5 parts by weight, more preferably about 0.1 to 4 parts by weight. When the average particle size is larger than the above range, or when the addition amount is larger than the above range, adhesion of the large particle size powder to the photosensitive drum occurs,
On the contrary, since the polishing effect on the photoconductor drum becomes too large, white stripes on the black solid portion of the copy image and black stripes on the white paper portion are likely to occur. On the other hand, when the average particle size is smaller than the above range, or when the addition amount is smaller than the above range, the contact area between the toner and the photoconductor does not decrease and the transfer efficiency deteriorates.

A predetermined amount of the large particle size powder is mixed and dispersed with the toner particles. For mixing and dispersing, for example, a Henschel mixer, a ball mill or the like can be used. When adding the above-mentioned finely powdered external additive that has been conventionally used together with the addition of the large particle size powder, the addition may be performed simultaneously regardless of the order of addition with the large particle size powder. Alternatively, either one may be added first.

The carrier to be combined with the toner of the present invention is not particularly limited, and carriers conventionally used can be used as they are.

[0024]

EXAMPLES Hereinafter, examples and comparative examples of the present invention will be described.
The two-component developer toner will be described in detail below.
The toner is not limited to these examples only.
Yes. Examples 1-4 and Comparative Examples 1-3 (For the content of magnetic materials
(Effect of) (1) Manufacture of toner Styrene-acrylic resin is used as the binder resin.
Carbon black, paraffin wax and magnetic materials
Magnetite (trade name "BL-
100 "and an average particle size of 0.5 μm) are shown in Table 1, respectively.
It was added in a ratio and melt-kneaded with a twin-screw extruder. Then,
The kneaded material is crushed with a jet mill and air classification is performed with a classifier.
Then, predetermined toner particles were obtained.

The toner particles have an average particle size of 0.001.
Hydrophobic silica fine particles of μm (trade name "R-972" manufactured by Nippon Aerosil Co., Ltd.) were added at a ratio of 0.3 parts by weight to 100 parts by weight of the toner particles, and the mixture was mixed with a Henschel mixer.
Mixed and dispersed for minutes. Then, an acrylic resin powder having an average particle diameter of 0.15 μm (“NTP-
1 ") was added at a ratio of 1 part by weight to 100 parts by weight of toner particles, and mixed and dispersed for 2 minutes by a Henschel mixer to obtain a toner. (2) Evaluation Test Toners obtained in each of the examples and comparative examples were mixed with a ferrite carrier having an average particle size of 80 μm and uniformly mixed with stirring to prepare a two-component developer having a toner concentration of 3.5%. . Then, using an electrophotographic copying machine (trade name “DC-7085”) manufactured by Mita Industry Co., Ltd., a total of 10,000 sheets were copied for each predetermined number of sheets.

The original used for copying was a character original having an area ratio of black portion of 8%, and the original sampled for every predetermined number of sheets had an area ratio of black portion including black solid portion of 15%. . Each test method is as follows. (a) Measurement of image density (ID) Measurement of the density of the black solid part in up to 10,000 copies of a predetermined number of copies using a reflection densitometer (Model TC-6D manufactured by Tokyo Denshoku Co., Ltd.) did.

(B) Toner scattering The toner scattering inside the copying machine at the end of copying 10,000 sheets was observed and evaluated according to the following criteria. ◯: No toner scattering X: Toner scattering (c) Particle size The toner particle size was measured with a Coulter counter (manufactured by Coulter). The initial particle size shown in the table means the average particle size of the toner before copying.

(D) Transfer efficiency The amount of toner in the toner hopper before the start of copying and the amount of toner in the toner hopper after copying 10,000 sheets were measured, and the difference between them was measured as the toner consumption amount after copying 10,000 sheets. Was calculated. On the other hand, the amount of toner collected in the cleaning process during the copying of 10,000 sheets was measured to obtain the toner recovery amount. Then, from the toner consumption amount and the toner recovery amount, the toner transfer efficiency was calculated by the following formula.

[0029]

[Equation 1]

(3) Results The results of the evaluation test are shown together with the blending amount of each toner used.
It shows in Table 1.

[0031]

[Table 1]

From Table 1, it can be seen that when no magnetite, which is a magnetic material, is added (Comparative Example 1), the image density is high at the initial stage of copying, whereas the image density is rapidly reduced thereafter. . On the other hand, toner scattering also occurs and the transfer efficiency is deteriorated. Further, when the added amount of magnetite is excessive (Comparative Examples 2 and 3), the toner scattering and the transfer efficiency are good, but the image density is poor from the beginning of copying and the copying speed is reduced thereafter.

On the other hand, in Examples 1 to 4, the image density did not change significantly during copying of 10,000 sheets and was almost stable.
It is also good in terms of toner scattering and transfer efficiency. Examples 5 to 8 and Comparative Examples 4 to 6 (Effect of addition of large particle size powder to toner surface) (1) Manufacture of toner Predetermined toner particles were obtained in the same manner as in Examples 1 to 4. After mixing and dispersing hydrophobic silica fine particles in the particles, as a large particle size powder, an acrylic resin powder having an average particle size of 0.15 μm (“NTP-1” manufactured by Nippon Paint Co., Ltd.) or an average particle size of 0.5 μm Magnetite powder (see "BL
-100 ") was added at various ratios shown in Table 2 to 100 parts by weight of toner particles, and mixed and dispersed for 2 minutes with a Henschel mixer to obtain a toner. (2) Evaluation test In the same manner as in Examples 1 to 4, the image density (ID), toner scattering, initial particle size, and transfer efficiency were measured. Furthermore, it was visually observed whether or not white streaks were generated in the black solid portion in the copied image, and the evaluation was made according to the following criteria.

When two or more white stripes having a length of 1 mm or more were found in the black solid area per 3 cm × 3 cm, white stripes were defined as white stripes, and when the white stripes were less than that, no white stripes were defined. (3) Results The results of the above evaluation test are shown in Table 2 together with the blending ratio of each toner used.

[0035]

[Table 2]

From Table 2, the fruit to which the acrylic resin powder was added
Compared to the toner of Comparative Example 4 in which the toner of Example 5 is not added,
Improve the transfer efficiency and prevent the toner from scattering.
Yes, it is possible to prevent the decrease of image density.
It Similar results were obtained by replacing the acrylic resin powder with a magnet
It was also obtained with the toners of Examples 6 to 8 to which the powder of nitrite was added.
There is. On the other hand, a comparative example in which magnetite powder was excessively added.
6 shows good transfer efficiency and prevents toner scattering.
And the image density is stabilized, but added excessively
Due to the influence of the magnetite powder that has been formed
Ji was occurring. Example 9 and Comparative Examples 7-8 (Large particle size powder on toner surface
(Effect of addition of body) (1) Production of toner Toner particles were obtained in the same manner as in Examples 1 to 4.
After mixing and dispersing hydrophobic silica particles in the toner particles,
Various acrylic resins with different average particle sizes as powder particles
Powder or magnetite powder to 100 parts by weight of toner particles
To the Henschel mixer.
And mixed and dispersed for 2 minutes to obtain a toner.

The large particle size powder used in Example 9 is magnetite powder having an average particle size of 0.8 μm (trade name “RB-BL” manufactured by Titanium Industry Co., Ltd.). The powder used in Comparative Example 7 was silica powder having an average particle size of 0.01 μm (trade name “R974” manufactured by Nippon Aerosil Co., Ltd.), and the powder used in Comparative Example 8 was magnetite having an average particle size of 4.0 μm. It is powder (trade name "BL-SP" manufactured by Titanium Industry Co., Ltd.). (2) Evaluation test In the same manner as in Examples 5 to 8, the image density (ID), toner scattering, initial particle size, transfer efficiency, and the presence or absence of white stripes on the black solid portion of the copied image were tested. . (3) Results The results of the above evaluation test are shown in Table 3 together with the blending ratio of each toner used and the results of Example 5 (using acrylic resin powder) and Example 7 (using magnetite powder) described above.
Shown in.

[0038]

[Table 3]

From Table 3, the particle size of the added powder is 0.01
When it is μm (Comparative Example 7), it is understood that the transfer efficiency is poor and a sufficient image density is not obtained. Further, when the particle size of the added powder is 4.0 μm (Comparative Example 8), the transfer efficiency is poor and white streaks are observed in the black solid part.

[0040]

As described above, the two-component developer toner of the present invention contains no charge control agent,
It is possible to prevent the toner characteristics from being stabilized and to reduce the image density and the transfer efficiency. Therefore, the toner of the present invention, by containing no charge control agent,
There is an effect that it can be manufactured at low cost.

[Brief description of drawings]

FIG. 1 is an explanatory diagram for explaining an improvement in transfer efficiency when a toner of the present invention is used.

FIG. 2 is an explanatory diagram for explaining a decrease in transfer efficiency when a toner containing no charge control agent is used.

FIG. 3 is a graph showing changes in image density depending on the presence or absence of a charge control agent.

FIG. 4 is a graph showing a change in charge amount depending on the presence or absence of a charge control agent.

[Explanation of symbols]

 10 Paper 11 Toner Particles 12 Photoreceptor 13 Toner Particles 14 Large Particle Powder s Gap

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Ken Arakawa 1-228 Tamatsukuri, Chuo-ku, Osaka-shi, Osaka Mita Kogyo Co., Ltd. (72) Kazuya Nagao 1-2-chome Tamatsukuri, Osaka-shi, Osaka No. 28 Mita Industry Co., Ltd.

Claims (1)

[Claims] 1. A large particle size powder containing 0.1 to 10 parts by weight of a magnetic material with respect to 100 parts by weight of a binder resin and having an average particle size of 0.05 to 1 μm on the surface thereof. Toner particles 10
A toner for a two-component developer containing no charge control agent, which is added in an amount of 0.05 to 5 parts by weight based on 0 parts by weight.