JPH1020540A - Electrostatic charge image developing toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrostatic latent image toner excellent in fluidity, electrification property and cleaning property by incorporating specified inorg. fine particles as an external additive having the same polarity or opposite polarity for electrification to the polarity of the toner. SOLUTION: The electrostatic charge image developing toner consists of at least a binder resin, coloring agent and charge controlling agent, and it contains as an external additive, first inorg. fine particles having the same electrification polarity to the toner polarity and second inorg. fine particles having the opposite electrification polarity to the toner polarity. In this case, the particle size of the first inorg. fine particles is larger than that of the second inorg. fine particles. If the particle diameter first inorg. fine particles is smaller than that of the second particles, good electrification rising property is not obtd. because the second inorg. particles having the opposite polarity to the toner base body touch the carrier in the contact electrification process. By using the electrostatic latent image developing toner aforesaid, good image with good image quality without no fog or filming can be easily obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner for developing an electrostatic latent image used in an image forming apparatus by an electrophotographic copying method in a copying machine, a printer, or the like.

[0002]

2. Description of the Related Art Conventionally, a toner for developing an electrostatic latent image has a certain degree of fluidity in order to satisfy toner supply from a supply bottle, developability, transferability, cohesiveness in a developing device, and the like. There is a need to have. Further, from the viewpoints of printing durability and storability, it is also required that good charging characteristics can be maintained even after long-term use.

[0003] In order to impart the above fluidity, it is common practice to add inorganic fine particles as an external additive to the toner. However, when using the inorganic fine particles having a charge polarity different from that of the toner base alone, good chargeability cannot be obtained,
In particular, when left in a high-temperature environment, the occurrence of fogging becomes remarkable with deterioration of the charging property.

On the other hand, the use of inorganic fine particles having the same charging polarity as the toner base has been studied. When the charge polarity of the inorganic fine particles is the same as that of the toner base, the charge amount distribution in the toner becomes sharp, and both chargeability and fluidity are achieved.
Although fogging can be avoided, since the external additive is used alone, when used for a long time, a phenomenon in which paper dust is filmed on the photoreceptor, particularly in a non-image area, occurs.
Filming also occurs on the developed image, resulting in poor cleaning performance. This is because a good static layer is hardly formed at the tip of the blade edge due to a decrease in toner supplied to the non-image portion, and paper powder directly attached to the surface of the photoconductor is embedded in the photoconductor by the cleaning blade. it is conceivable that.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a toner for developing an electrostatic latent image which is excellent in fluidity, charging property and cleaning property.

[0006]

According to the present invention, there is provided a toner for developing an electrostatic image comprising at least a binder resin, a colorant and a charge control agent, wherein the first inorganic fine particles having the same polarity as the toner are used as an external additive. And a second inorganic fine particle having a polarity opposite to the polarity of the toner, wherein the particle diameter of the first inorganic fine particle is larger than that of the second inorganic fine particle.

The toner for developing an electrostatic latent image according to the present invention is obtained by externally adding two kinds of inorganic fine particles having different charging polarities to a toner base. One of the two types of inorganic fine particles is a first inorganic fine particle having the same charge polarity as the toner base,
The other is second inorganic fine particles having a polarity opposite to that of the toner matrix, and the particle diameter of the first inorganic fine particles is larger than that of the second inorganic fine particles. If the particle diameter of the first inorganic fine particles is smaller than that of the second inorganic fine particles, good charge rising properties cannot be obtained because the carrier and the second inorganic fine particles of the opposite polarity to the toner base come into contact during contact charging. Here, the “toner base” is a toner particle composed of a binder resin, a colorant, and other desired additives such as a charge control agent. In the toner manufacturing process, when an external additive is added, It refers to the toner particles at the stage.

Further, in the present invention, the BET specific surface areas of the first inorganic fine particles and the second inorganic fine particles added as external additives are respectively S ₁ and S ₂ (m ²
/ g), and the added weight per 1 kg of the toner matrix is A ₁
And A ₂ (g), and the coverage of the external additive on the toner particles is B ₁ and B ₂ (%), respectively.

(Equation 2) Is preferably 0.5 to 5. More preferably, the ratio takes a value of 0.5 to 3. If this ratio is smaller than 0.5, the ratio of the second inorganic fine particles is large, so that the probability that the second inorganic fine particles come into contact with the carrier is increased, and the fog is deteriorated. On the other hand, if it exceeds 5, the opposite polarity component is reduced, so that a good residual toner layer cannot be formed at the tip of the blade edge, and the cleaning property such as filming deteriorates.

The coverage B is given by the following formula:

(Equation 3) Is defined by The BET specific surface area was measured by MS12 (manufactured by Cantachrome), and the average particle diameter was measured by a transmission electron microscope photograph and averaged.

The inorganic fine particles used in the present invention include metal oxides such as silica, titania and alumina. Silica includes, for example, commercially available Aerosil R-972 and R-974, silica D-17, R-8
12 and RA-200, titania, for example, commercially available T-805, STT, and alumina, for example, commercially available RX-C. These metal oxides are usually negatively charged by contact with a carrier or the like when used in an untreated state as they are, and are positively charged when subjected to a hydrophobic treatment by a hydrophobizing agent, for example, an aminosilane coupling treatment, that is, A desired charging polarity can be easily provided by the above operation.

When the toner of the present invention is used as a toner for a two-component developing system, the inorganic fine particles are charged by friction with an externally added carrier. On the other hand, when the toner is used as a toner for a one-component developing method, the toner is charged by a charging mechanism in a developing device. As a result, if the charged polarity of the fine particles is the same as the toner base, the fine particles become the first inorganic fine particles, and if the charged polarity is the opposite polarity, the fine particles become the second inorganic fine particles.

The first inorganic fine particles may be larger than the second inorganic fine particles. Specifically, the first inorganic fine particles are 10 to 40 nm, preferably 15 to 30 nm, and the second inorganic fine particles are 5 to 20 nm. Preferably it has an average particle size of 10 to 15 nm. Regarding the amount of addition, the first and second inorganic fine particles are preferably externally added in an amount of 1 to 100 g per 1 kg of the toner base. Further, regarding the BET specific surface area, the first and second inorganic fine particles are 50 to 300, respectively.
It is preferably m ² / g.

The toner for developing an electrostatic latent image according to the present invention is obtained by externally adding the above-mentioned inorganic fine particles to a toner base and mixing them using a conventional mixer, for example, a Henschel mixer. When the toner of the present invention is used as a toner for a two-component developing system, it is preferable to externally add and mix a carrier after externally adding and mixing inorganic fine particles.

The toner matrix of the present invention comprises at least a binder resin, a colorant and a charge control agent. As the binder resin, conventionally used styrene-based copolymers, for example, polystyrene and polyvinyl toluene, styrene-based copolymers, for example, styrene-acrylic copolymer, styrene-propylene copolymer, styrene-
Examples thereof include vinyl toluene copolymer and styrene-maleic acid copolymer, and other polymers such as polymethyl methacrylate, polyvinyl chloride, polyethylene, polypropylene, polyamide, and polyester.

The colorant used in the present invention is not particularly limited. For example, carbon black, lamp black, nigrosine dye, aniline blue, phthalocyanine blue, banza yellow G, and the like conventionally used in electrophotography. Rhodamine 6G lake, chrome yellow, quinacridone, benzidine yellow, rose bengal, triacrylmethane dye and monoazo dye. The amount of these coloring agents is 1 to 20 parts by weight, preferably 3 to 10 parts by weight, based on 100 parts by weight of the binder resin.

As the charge control agent, those commonly used in conventional dry developers can be used. Examples of the positive charge control agent include Bontron O3, a nigrosine dye of an azine compound, Examples of the negative charge control agent include Bontron S-3 of a gold-containing azo dye.
4, E-82 of oxynaphthoic acid-based metal complex, E-84 of salicylic acid-based metal complex, and E-89 of phenol-based condensate. The charge control agent is used in an amount of 0.5 to 10 parts by weight, preferably 1 to 5 parts by weight, based on 100 parts by weight of the binder resin.

As a method for producing a toner matrix composed of the above-mentioned materials, any conventionally used method may be adopted, for example, a method of producing by a kneading and pulverizing method, or a method of granulating and aggregating in a wet system and drying. In the latter case, it may include a polymerization process such as a suspension polymerization method or an emulsion polymerization method, or may include a polymerization process such as a suspension method or an emulsion dispersion method. There may be no granulation method. Preferably, it is a method of producing by a kneading and pulverizing method. However, in any of the above production methods, the average particle size of the toner base (particles) is set to 5 to 20 μm, preferably 6 to 12 μm. If it is less than 6 μm, it will be difficult to handle it in a developing device, and if it is more than 12 μm, the texture of the image will be coarse and it will not fit the trend of the times.

The toner matrix may contain other additives as necessary. For example, an anti-offset agent, magnetic powder, resin beads and the like can be mentioned. As an anti-offset agent, paraffin wax, polyolefin wax,
Carnauba wax, alcohol, fatty acid, acid amide, ester, ketone, hydrogenated castor oil, vegetable wax, animal wax, mineral wax, petrolactam and derivatives thereof. The amount of these additives is 1 to 10 parts by weight, preferably 2 to 5 parts by weight, based on 100 parts by weight of the binder resin.

The toner of the present invention can be used as either a toner for a one-component developing system or a toner for a two-component developing system. Can be externally added. As the carrier, any of those conventionally used for a toner for a two-component developing system may be used, and examples thereof include a binder-type carrier and a coat carrier. The present invention is described in more detail by the following examples.

[0020]

Example 1 100 parts by weight of a binder resin (styrene-acrylic copolymer: average molecular weight 7,000) 9 parts by weight of a colorant (carbon black: Mogal 1: manufactured by Cabot Corporation) 9 parts by weight of a charge control agent (nigrosin) 4.5 parts by weight The above materials were kneaded with three rollers, pulverized and classified to obtain a positively chargeable toner base material having an average particle diameter of 10 μm. The following external additives were added to the obtained toner base, and mixed with a Henschel mixer for about 3 minutes to obtain a toner.・ External additive 1a (silica: R974: particle size 0.012 μm) 0.05% by weight ・ External additive 2a 0.1% by weight (silica: Aerosil 130 treated with aminosilane coupling, particle size 0.016 μm)

A dispersion type carrier having an average particle diameter of 70 μm obtained by kneading, pulverizing and classifying the following materials is further externally added to the above-mentioned toner at a mixing weight ratio of 94: 6 and mixed, and a toner for a two-component developing system is obtained. Obtained. -Resin (PES: Tufton NE-1110: manufactured by Kao Corporation) 100 parts by weight-Cu-Zn-ferrite fine particles 500 parts by weight-CB (Ketjen Black EC: manufactured by Lion Yushi Co., Ltd.) 2 parts by weight-Silica (# 200: Japan 1.5 parts by weight (Aerosil)

Example 2 100 parts by weight of a binder resin (styrene-acrylic copolymer: average molecular weight 7,000) 9 parts by weight of a colorant (carbon black: Mogal 1: manufactured by Cabot Corporation) 9 parts by weight of a charge control agent (S- 34: manufactured by Orient Chemical Co.) 4.5 parts by weight After kneading the above materials with three rollers, pulverizing and classifying,
A negatively chargeable toner matrix having an average particle size of 10 μm was obtained. The following external additives were added to the obtained toner base in the following amounts, and mixed with a Henschel mixer for about 3 minutes to obtain a toner.・ External additive 1b (silica: R972: particle size 0.016 μm) 0.1% by weight ・ External additive 2b 0.1% by weight (silica: Aerosil 200 subjected to aminosilane coupling treatment, particle size 0.012 μm)

The dispersion type carrier produced in the same manner as in Example 1 was further added to the above toner at a mixing weight ratio of 94: 6.
The mixture was externally added and mixed to obtain a toner for a two-component developing system.

Example 3 A positively chargeable toner matrix was obtained in the same manner as in Example 1. Thereafter, a toner for a two-component developing system was obtained in the same manner as in Example 1, except that the following external additives were added to the obtained toner base in the following amounts.・ External additive 1a (silica: R974: particle size 0.012 μm) 0.03% by weight ・ External additive 2c 0.13% by weight (alumina: HEROLICRX-C with aminosilane coupling treatment, particle size 0.020 μm)

Comparative Example 1 A positively chargeable toner base was obtained in the same manner as in Example 1. Thereafter, a toner for a two-component developing system was obtained in the same manner as in Example 1, except that the following external additives were added to the obtained toner base in the following amounts.・ External additive 1a 0.15% by weight

Comparative Example 2 In the same manner as in Example 1, a positively chargeable toner matrix was obtained. Thereafter, a toner for a two-component developing system was obtained in the same manner as in Example 1, except that the following external additives were added to the obtained toner base in the following amounts.・ External additive 2a 0.2% by weight

Comparative Example 3 In the same manner as in Example 1, a positively chargeable toner matrix was obtained. Then, Example 2 was applied to the obtained toner matrix.
A toner for a two-component developing system was obtained in the same manner as in Example 1 except that an external additive was added.

Comparative Example 4 A positively chargeable toner base was obtained in the same manner as in Example 1. Thereafter, a toner for a two-component developing system was obtained in the same manner as in Example 1, except that the following external additives were added to the obtained toner base in the following amounts.・ External additive 1a 0.1% by weight ・ External additive 2b 0.1% by weight

The blow-off charge of the external additive and the carrier used in Examples 1 to 3 and Comparative Examples 1 to 4 was measured. Table 1 shows the results.

[0030]

[Table 1]

Table 2 shows the production conditions of the toner.

[0032]

[Table 2]

Using the two-component developing system toners obtained in Examples 1 to 3 and Comparative Examples 1 to 4, when the toner is a positively chargeable toner, a copying machine EP4050 (manufactured by Minolta) and a paper passing mode 4 sheets intermittent, when the toner is a negatively chargeable toner, copying machine Di30 (manufactured by Minolta), intermittent 2 sheets in paper feed mode, temperature 22 ° C, humidity 50%, consumption about 4
0mg / sheet, copy with Paper Comine 64 A4T, 1
Filming due to the adhesion of paper dust to the photoreceptor after 20,000 sheets was evaluated. In addition, when the toner was left at a high temperature (50 ° C.) for 24 hours, a high-temperature fog after 120,000 printings was evaluated in a 500-sheet continuous mode. Table 3 shows these results.
Shown in The fogging and filming were ranked as shown in Table 4.

[0034]

[Table 3]

[0035]

[Table 4]

From the above results, it is considered that the toners in Examples 1 to 3 have excellent image properties and durability, and this is attributed to good fluidity, chargeability and cleaning properties.

In Comparative Example 1, since the inorganic fine particles having a different polarity from the toner base were used alone, it is considered that the chargeability deteriorated and fog occurred. In Comparative Example 2, since the inorganic fine particles having the same polarity as the toner base were used alone, the charge amount distribution of the toner particles was sharpened, the amount of toner supplied to the non-image portion was reduced, and a good static layer was formed by the blade edge tip. It is considered that the formation of the toner particles became difficult, and the paper powder directly adhered to the surface of the photoconductor was buried in the photoconductor by the cleaning blade, thereby causing filming. In Comparative Examples 3 and 4, although the disadvantages in Comparative Examples 1 and 2 were slightly improved by adding two types of external additives, the particle diameter of the external additive having the same polarity as the toner base was different from that of the toner. Since it is not larger than that of the additive, it is considered that filming and fogging occurred due to a sharper distribution of charge amount and worsening of the chargeability than in the case of adding one kind of external additive.

[0038]

By using the toner for developing an electrostatic latent image having excellent fluidity, chargeability and cleaning property according to the present invention, it is possible to easily provide a high quality image free from fogging and filming. it can. Further, the toner of the present invention has excellent durability.

Claims (2)

[Claims] 1. An electrostatic image developing toner comprising at least a binder resin, a coloring agent and a charge controlling agent, wherein an external additive is a first inorganic fine particle having a charge polarity the same as the toner polarity; Including second inorganic fine particles,
A toner for developing an electrostatic image, wherein the particle diameter of the first inorganic fine particles is larger than that of the second inorganic fine particles. 2. The first inorganic fine particles and the second inorganic fine particles added as external additives have a BET specific surface area of S ₁ and S ₂ (m ² / g), respectively, and an addition weight per kg of the toner matrix of A. ₁ and A ₂ (g), and the coverage of the external additive with respect to the toner particles is B ₁ and B ₂ (%), respectively. 2. The toner for developing an electrostatic image according to claim 1, wherein the coverage ratio represented by the formula is from 0.5 to 5.