JPH03255461A - Developing method - Google Patents

Abstract

PURPOSE:To stabilize image densities by changing the triboelectrostatic charge polarity of the fine particles of the silica to be used for a start developer and the triboelectrostatic charge polarity of the fine particles of the silica to be used for a replenishing toner. CONSTITUTION:The start developer consisting of a carrier toner and the fine particles P1 of the silica is previously supplied to the developing device of an electrophotographic copying machine and the replenishing toner consisting of the toner and the fine particles P2 of the silica is supplied in order to replenish the consumed start developer. The fine particles P1 and P2 of the silica are so compounded with the start developer and the replenishing toner that the respective triboelectrostatic charge quantities of the toner, the fine particles P1 of the silica and the fine particles P2 of the silica, destinated as A, B1 and B2, with respect to the carrier, maintain the relations of the triboelectrostatic charge polarities that B1 is a reverse polarity and B2 is the same polarity with regard to the triboelectrostatic charge polarities of A, then the development is executed. The increase in the initial triboelectrostatic charge quantity at the time of continuous copying is prevented in this way and the stable image densities are obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a developing method for developing an electrostatic charge image formed by electrophotography or the like.

[Conventional technology]

Conventionally, in electrophotography, an electrostatic image formed on a photoreceptor is developed with a developer, and then transferred and fixed onto a transfer paper.

As a developer used in this developing step, a dry two-component developer consisting of toner and carrier is known.

In recent years, with the demand for continuous copying of a large number of sheets using electronic copying machines, there has been a demand for a longer lifespan for the dry two-component developer, and specifically, there is a need for stable image quality;
It is necessary to satisfy characteristics such as no toner scattering and (2) low toner consumption. In order to satisfy these characteristics, the carrier constituting the two-component developer must constantly triboelectrically charge the toner with a desired polarity and a sufficient amount of charge over a long period of time.

However, in conventional developing methods using two-component developers, the toner and carrier are mixed and stirred in the developing device, causing the toner to fuse to the carrier surface and contaminating the carrier particle surface with the toner, a so-called spent phenomenon. There was a phenomenon. When toner is spent on the carrier surface, the triboelectricity becomes unstable, and as the number of copies increases during continuous copying, the amount of triboelectricity of the toner decreases, causing blurring in images. This caused problems such as toner scattering and toner scattering.

In general, in order to create a dry two-component developer, two components are needed: ■ A carrier that does not cause the above-mentioned spent phenomenon even when used for a long time, and ■ A toner that does not cause toner scattering, that is, a carrier that has sufficient triboelectric charge. In frictional charging with
When the amount of triboelectric charge increases quickly, it is necessary to develop a developer tank agitation system with a structure that quickly increases the amount of triboelectricity of the replenished toner.

In order to meet this requirement, it is known that the surface of the carrier is coated with various resins to prevent the formation of a toner film. However, carriers with a large coating amount of resin have the disadvantage that the amount of triboelectric charging of the toner becomes higher than necessary, and the image density during initial copying becomes low.

In such a case, there is a problem in that a certain number of copies must be made in the initial stage after the start of copying in order to obtain a stable amount of triboelectric charge and image density.

[Problem to be solved by the invention]

The present invention has been made in view of the above circumstances, and provides a developing method in which the amount of triboelectric charging is appropriate from the initial stage and the image density is stable during continuous copying even if the amount of resin coating on the carrier is increased. The purpose is to

[Means to solve the problem]

The present inventors have conducted various studies to improve the above-mentioned problems, and as a result, they have arrived at the present invention by focusing on the polarity of the silica fine particles added to the start developer and replenishment toner.

That is, the present invention provides carrier, toner, and silica fine particles P.
A developing method in which a starter developer consisting of , is supplied in advance to a developing device of an electronic copying machine, and replenishment toner consisting of toner and silica particles P2 is supplied to supplement the consumed start developer, the method comprising: The triboelectric charge amounts of the toner, silica fine particles P1, and silica fine particles P2 on the carrier are A, B+, and B!, respectively. In this case, silica fine particles P1 and P2 are blended into the starting developer and the replenishment toner so that B maintains the opposite polarity to the frictional charging polarity of A and the frictional charging polarity of B2 has the same polarity. This is a developing method characterized by developing.

The present invention will be explained in detail below.

The toner constituting the present invention includes a binder resin, a charge control agent,
6. The binder resin is manufactured to have an average particle size of 5 to 15 μm by tri-blending the colorant and other additives added as necessary to a predetermined composition, and then going through melt mixing, pulverization, and classification steps. Examples of the resin include styrene resin, polyacrylic ester resin, styrene-acrylic ester copolymer resin, polyvinyl chloride, polyvinyl acetate, polyvinylidene chloride, phenol resin, epoxy resin, and polyester resin.

As the charge control agent, for example, nigrosine dyes, alkoxylated amines, quaternary ammonium salts, alkylamides, metal complex salts of monoazo dyes, chlorinated polyolefins, naphthenic acid metal salts, fatty acid metal salts, etc. can be used depending on the desired polarity. Add.

Examples of the coloring agent include carbon blank, monoazo red pigment, disazo yellow pigment, quinacridone magenta pigment, and anthraquinone dye.

Other additives include lubricants such as polytetrafluoroethylene powder, abrasives such as cerium oxide, and fixing aids such as low molecular weight polypropylene.

Next, the silica fine particles used in the present invention will be explained in detail.

The silica fine particles P and P2 in the present invention are negatively or positively charged with respect to the carrier, and it is possible to use hydrophobic or hydrophilic silica fine particles.

Examples of such fine silica particles include the following.

That is, positively charged silica fine particles are, for example, colloidal silica particles having a particle diameter of several microns to 10 microns, preferably several microns to 1 micron, whose surface is coated with an aminosilane represented by the following general formula (so-called aminofuncuccinal silane). The processed one will be applied.

Xll5IYFI (X is an alkoxy group or a chloro atom, an integer of mbal to 3, Y is a hydrocarbon group having a primary to tertiary amino group, n is an integer of 3 to 1) Specific examples of such compounds As H3 HzN-CHgCHJHCH"CHzCLSi-(OC
Hs) zHJ-CONH-C)lzCHzCHz-5
i-(OCzH:+) :IHzN-CHzCHtCH
tSi (OCHzCHx)! HtNCHzCHJH
CHzC)lzcHzsl (OCHi) 3HzNC
HzCHzCHzSi (OCH3) xHJCHzC
HJHCHzCHJHCHzCHzCHzSi (OC
H3) 5HsCzOCOCHzCHJHCHzCHt
CHzSi(OCHs) xHsCzOCOCHzCH
zNHCHzCHzNHCHzC)lzcHzsi (
OCH3) 5H5CzOCOCFlzCLNHCHHz
ChzNFICF! zcHJIHcLcHJ)lcf(
zCHzC) IzSi (OCH:l) 3Ni(zc
Examples include aH4si(OCRl)3CJsN)ICHzCHzCHzSi(OCHt)3, and polyaminoalkyltrialkoxysilane, which may be used alone or in combination of two or more.

A method for treating the surface of the colloidal silica with Akunobuankusi 3-narsilane is, for example, by stirring the colloidal silica and spraying or vaporizing a solution of the aminosilane compound thereon, or by turning the colloidal silica into a slurry. It can be easily processed by adding a solution of the aminosilane compound dropwise to the solution while stirring.

Examples of the negatively charged silica particles include silica particles that have been hydrophobized with an organosilicon compound.

In the present invention, the silica fine particles are used by blending them into a start developer and a replenishment toner. Specifically, silica fine particles are mixed with the toner of the start developer and replenishment toner and attached to the surface of the toner using a general mixer such as a V-type mixer, a turbine-type stirrer, or a Henschel mixer, or mechanically. The silica particles may be attached using a surface modification device that can firmly attach a portion of the silica particles to the surface of the toner by embedding or thermal fusion using a strong impact force.

The amount of the silica fine particles deposited is 11 to 1 heavy part of O per 100 parts by weight of toner, preferably 0.2 to 0.8 part by weight.

In the present invention, the object of the present invention can be achieved by changing the friction charge polarity of the silica fine particles P1 used in the start developer and the friction charge polarity of the silica fine particles P2 used in the replenishment toner. For example, if the frictional charging polarity of the toner with respect to the carrier is negative, the frictional charging polarity of the silica fine particles P blended in the start developer is positive charging, and the frictional charging polarity of the silica fine particles P2 blended in the replenishment toner is
If the tribo-charging polarity of the toner with respect to the carrier is positive, the tribo-charging polarity of the silica fine particles P1 blended in the start developer is negative, and the tribo-charging polarity of the silica particles P1 blended in the starting developer is negative, and the triboelectric polarity of the silica particles P1 blended in the starting developer is negative. Regarding the frictional charging polarity of the fine particles P2, positively chargeable silica fine particles are selected.

The friction charge polarity in this case is determined from a relative measurement value with the carrier to be combined, and is determined as follows. In other words, normal temperature and humidity (20℃/6
Carrier 19 left for 20 hours in an environmental condition (5% RH)
9.0g and toner or silica fine particles P, or Pzl, O
Each g of the mixture was placed in a 250 cc polyethylene bottle, and the polyurethane bottle was placed in a rotating device with constant rotation, and then rotated for mixing and agitation.

Thereafter, the triboelectric charge amounts A, B, and B2 of the toner, silica fine particles P, or Pt are measured by a blow-off charge measuring device, and the silica fine powder to be used as the starting developer or replenishment toner is selected depending on the polarity at that time. be.

On the other hand, the carrier used in the present invention has a particle size of 40. erm ~ 300μm iron powder, ferrite, granulated magnetite, etc. on the surface of silicone resin, 7-component resin, etc.
Although resin-coated carriers coated with resins such as acrylic acid esters such as methyl acrylate, methyl, ethyl, and butyl methacrylate, and vinyl ethers such as methyl acrylate, acrylamide, and vinyl isobutyl ether, or carriers without resin coating can be used. A carrier coated with silicone resin is effective in extending the life of the developer.

Note that the start developer has silica particles P on the surface of the toner.
1, and then mix the toner to which the silica fine particles P are attached with a carrier using a known mixer such as a blender or a cone blender.

[For production]

In the present invention, as a method of providing a long-life developer that is less likely to cause spent, a high-resistance carrier with a large amount of resin coating is used from the carrier side, and the following toner is used from the toner side.

In other words, by using fine silica particles whose triboelectric polarity is opposite to that of the toner as a starting developer, the charge distribution of the toner whose surface has been treated with fine silica particles is sharpened and lowered, thereby making it possible to improve initial copying. In addition, by making the frictional charging polarity of the silica fine particles used in the replenishment toner the same as that of the toner, the amount of frictional charging with the carrier increases quickly, and the initial By shifting the sharp charge amount distribution during copying to a higher level, appropriate image density can be maintained.

Due to these effects, the present invention provides an appropriate image density from the initial copying time, maintains sufficient image density even after toner replenishment is started, and has no toner scattering.
It is possible to provide a developing method that consumes less toner.

〔Example〕

Next, the present invention will be explained with reference to Examples. It should be noted that all parts expressed herein are parts by weight.

Example 1 It was as follows.

Table 1 The mixture according to the above formulation was hot-melted and kneaded using an extruder, and then pulverized and classified to obtain a negatively charged toner having an average particle size of 12 μm. Next, positively chargeable silica fine particles P are added to 100 parts of the toner.

After 0.4 part was attached to the surface of the toner using a Henschel mixer, 4 parts of the toner to which the silica fine particles P1 were attached were sufficiently mixed with 96 parts of silicone coated ferrite carrier to prepare a start developer.

On the other hand, a supplementary toner was prepared by attaching 0.3 parts of negatively charged silica fine particles P to the surface of the toner using a Henschel mixer based on 100 parts of the above toner.

The above toner, silica fine particles P, and the triboelectric charge amounts A, B+, and B2 of the silica fine particles P2 and the silicone coated ferrite carrier are shown in Table 1. Example 2 The mixture with the above formulation was hot-melted and kneaded using an extruder. Thereafter, it was crushed and classified to obtain a negatively charged toner having an average particle size of 11 μm. Next, positively chargeable silica fine particles P are added to 100 parts of the toner.

After adhering 0.3 part of the toner to the surface of the toner using a Henschel mixer, 3.5 parts of the toner to which the silica fine particles P were attached and 96.9 parts of the silicone coated ferrite carrier were added.
A starting developer was prepared by thoroughly mixing 5 parts with 5 parts.

On the other hand, a replenishment toner was prepared by attaching 35 parts of negatively chargeable silica fine particles PZO to the surface of the toner using a Henschel mixer based on 100 parts of the above toner.

Note that the triboelectric charge amounts of the toner, silica fine particles P, and silica fine particles P2 and the silicone coated ferrite carrier were as shown in Table 2 for A, BI, and B2.

Table 2 Example 3 1 7 parts of carbon blank ((Viscol 550 P manufactured by Sanyo Kakai Kogyo Co., Ltd.) The mixture according to the above formulation was hot-melted and kneaded using an extruder, and then crushed and classified to produce positive particles with an average particle size of 11 μm. A chargeable toner was obtained.Next, negatively chargeable silica fine particles P were added to 100 parts of the toner.

After adhering 0.3 part of the toner to the surface of the toner using a Henschel mixer, 3.5 parts of the toner to which the silica fine particles P were attached and 96.9 parts of the silicone coated ferrite carrier were added.
A starting developer was prepared by thoroughly mixing 5 parts with 5 parts.

On the other hand, a replenishment toner was prepared by attaching 20.3 parts of positively charged silica fine particles P to the surface of the toner using a Henschel mixer based on 100 parts of the above toner.

The triboelectric charge amounts of the toner, silica fine particles P1 and silica fine particles P, and the silicone-coated ferrite carrier were as shown in Table 3 for A, B+, and B2.

Table 3 Comparative Example 1 4 parts of the replenishment toner of Example 1 and 96 parts of silicone-coated ferrite carrier were thoroughly mixed to prepare a start developer, and the replenishment toner was replenished during continuous copying to provide a comparative example.

Comparative Example 2 A starter developer was prepared by thoroughly mixing 3.5 parts of the replenishment toner of Example 2 and 96.5 parts of silicone coated carrier, and the replenishment toner was replenished during continuous copying to provide a comparative example.

Comparative Example 3 Toner 3.5 to which silica fine particles P1 of Example 2 were attached
A starting developer was prepared by thoroughly mixing 96.5 parts of silicone-coated ferrite carrier, and toner to which cough silica fine particles P were attached was replenished during continuous copying to prepare a comparative example.

The start developer obtained in Examples 1 to 3 and Comparative Examples 1 to 3 above and the replenishment toner replenished during continuous copying were installed in a commercially available high-speed copying machine (60 sheets/min) to print up to 50,000 copies. Continuous copying was evaluated and the results shown in Table 3 were obtained.

In Table 3, the image density was measured using a Macbeth reflection densitometer, and the amount of triboelectric charge was measured using a blow-off charge amount measuring device. Further, the toner consumption amount is the average value of the toner consumption amount required for 10,000 copies after continuous copying, and toner scattering was evaluated by visually observing the area around the developing device.

As is clear from the results in Table 3, in the examples using the developing method of the present invention, the image density was stable from the initial stage to after 50,000 copies, the amount of toner consumed was small, and no toner scattering occurred. On the other hand, Comparative Example 1 and Comparative Example 2
The image density was low up to the first sheet, and in Comparative Example 3, the amount of toner consumed was large and toner scattering occurred, which caused problems in practical use.

〔Effect of the invention〕

The developing method of the present invention can prevent an initial increase in the amount of triboelectric charge during continuous copying, so that a stable image density can be obtained from the initial stage.

Claims (1)

[Claims] A starter developer consisting of carrier, toner, and silica fine particles P_1 is supplied in advance to the developing device of the electronic copying machine, and a supplementary toner consisting of toner and silica fine particles P_2 is supplied to supplement the consumed start developer. In the developing method, when the triboelectric charge amounts of the toner, silica fine particles P_1, and silica fine particles P_2 with respect to the carrier are A, B_1, and B_2, B_1 has a polarity opposite to the triboelectric polarity of A, and B_2 has a polarity opposite to that of A. Silica fine particles P_1 and P_2 are arranged so as to maintain the friction charge polarity relationship of the same polarity.
A developing method characterized in that development is carried out by blending the above-mentioned starting developer and replenishment toner.