JPH07191539A - Toner replenishing method for two-component type developer for dry processing - Google Patents

Abstract

PURPOSE:To provide a toner replenishing method maintaining high image quality without causing the deterioration of image quality such as surface fogging and the deterioration of image density due to the fluctuation of toner density even for continuous copying for the two-component type developer for dry processing. CONSTITUTION:As for a method detecting the deficient quantity of toner within a developing device 201 housing the two-component type developer and replenishing the developing device 201 with the toner (toner of two-component type developer for dry processing) based on the detection; a toner replenishment container 1 horizontally installed is filled with powdery toner having cohesive degree 10-30%, and the toner equivalent to the deficient quantity is supplied to the inside of the developing device 201 from the tip part of a toner replenishment container 1 by rotating and driving the toner replenishment container 1 and also controlling the number of revolution in accordance with the deficient quantity of the toner within the developing device 201. Then, the usage of the substance of a cartridge form is advantageous for the toner replenishment container 1.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a toner replenishing method for a dry two-component developer used for visualization such as electrophotography and electrostatic printing.

[0002]

2. Description of the Related Art A so-called dry type two-component developer comprising a mixture of carrier particles and toner particles is well known and put to practical use. In this dry two-component developer, minute toner particles are held on the surface of a relatively large particle by the electric force generated by the friction between the particles, and when the electrostatic latent image is approached, the electrostatic latent image is formed. The attraction force in the latent image direction with respect to the toner particles due to the electric field formed overcomes the binding force between the toner particles and the carrier particles, and the toner particles are attracted and attached onto the electrostatic latent image to visualize the electrostatic latent image. It is a thing. A system is generally used in which when the toner is consumed by development, various sensors detect the toner density and the toner is replenished from a replenishing hopper.

This replenishing hopper is separated from the conventional developing unit, which is integrated with the developing unit, with the increasing size and speed of the copying machine, and is separated from the developing unit independently. The type provided is often used because of its capacity efficiency. Conventionally, such a developing device and a detached replenishment hopper were arranged vertically in the machine, but the vertically arranged one has a toner replenishment regulating device, and the mechanism is complicated. For this reason, a horizontally arranged replenishment hopper has been proposed for the purpose of simplification and ensuring capacity.

However, in such a system in which the container is horizontally arranged and the container is rotated to replenish the toner, a large amount of toner can be put in the replenishing hopper as compared with the conventional system, so that the toner runs out during copying. Although it has a difficult effect, it does not have a replenishment control device, and the toner replenishment amount with respect to the rotation of the hopper tends to fluctuate depending on the toner filling state in the hopper and the toner agglomeration state. There is a problem that the toner density control system for replenishing the amount of toner does not function sufficiently, and as a result, image fouling such as background fog due to excessive toner replenishment and image density reduction due to insufficient toner replenishment occurs.

On the other hand, a styrene-acrylic resin is generally widely used as a binder resin for toner. However, due to recent energy-saving fixing and higher copying speed, less energy can be used for fixing, and so-called low-temperature fixing toner having a low fixable temperature is desired. However, it is known that when the styrene-acrylic resin is deteriorated in thermal characteristics, the storage stability against heat when it is made into a toner is significantly deteriorated. On the other hand, the polyester resin is extremely useful as a low-temperature fixing toner because the polyester resin does not deteriorate in storability even when its thermal characteristics are deteriorated and good low-temperature fixing property is obtained.

By the way, the wax component is a substance that improves the releasability from the fixing roller at the time of fixing, and when using a fixing device that does not apply a releasable substance such as silicone oil to the fixing roller, It is generally contained in the toner. As the releasing wax, low molecular weight polypropylene has been generally used conventionally, but since the melting temperature is relatively high, sufficient releasing property may not be obtained by low temperature fixing. Carnauba wax has a low melting temperature and exhibits sufficient releasability even at low temperature fixing. In particular, the free fatty acid-type carnauba wax is obtained by removing free fatty acids from carnauba wax as a raw material, so that the acid value becomes 5% or less, and it becomes finer crystals than the conventional carnauba wax and becomes a binder resin. The dispersion diameter is small and the dispersibility is improved.

However, the low-temperature fixing toner containing such a wax component has poor fluidity due to the adhesiveness of the resin and wax. As a method for solving this, a method of adding a fluidity improver has been devised. Examples of the fluidity improver include, for example, JP-A-51-120631.
No. 48, No. 48-47346, No. 46-5782, No. 5
As disclosed in Japanese Patent Publication No. 1-101535, a method of using an inorganic fine powder of silica, titanium oxide, aluminum oxide or the like has been proposed, but it improves the fluidity of a low temperature fixing toner containing a wax component. To this end, it is extremely useful to add silica.

In recent years, demands for higher image quality in copying have increased in the market, and the conventional volume average particle size is 10 to 15 μm.
With the toner of m, sufficient image quality cannot be obtained. Therefore, also in the present invention, it is important to set the volume average particle diameter of the toner within the range of 5 to 10 μm. But,
It is not sufficient to simply reduce the volume average particle diameter for achieving high image quality, and the amount of fine powder contained in the toner, that is, the proportion of the toner having a particle diameter of 5 μm or less is important. But,
The larger the amount of fine powder toner, the better the image quality, but the fluidity and cleaning property of the toner tend to deteriorate. It is important that the amount of the fine powder toner is in the range of 30 to 60%.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to improve the conventional problems in the replenishing method using a toner replenishing container installed horizontally in a copying machine, and to prevent fog due to fluctuations in toner concentration even in continuous copying. The present invention provides a method for replenishing toner in a dry two-component developer that can maintain high image quality without causing image quality deterioration such as image density reduction.

[0010]

SUMMARY OF THE INVENTION The present invention detects a shortage amount of toner in a developing device containing a two-component developer, and based on this detection, the toner (dry two-component developer In the method of replenishing the toner in the developing device, a toner replenishing container installed horizontally is filled with powder toner having an aggregation degree of 10 to 30%, and the toner replenishing container is rotatably driven. The number of revolutions is controlled according to the shortage amount, and the toner matching the shortage amount is supplied from the tip of the toner supply container into the developing device. It is advantageous that the toner replenishing container here is of a cartridge type.

The present invention will be described in more detail below. In the method of the present invention, the toner supply container placed horizontally is filled with the toner, and the new toner amount to be introduced into the developing device is determined in response to the toner amount measured in the developing device.

In the method of the present invention, powder toner (replenishment toner) having an aggregation degree of 10 to 30% is stored in the toner supply container. Here, the degree of cohesion was measured by using a powder tester manufactured by Hosokawa Micron Co., Ltd.
Set each 5μm and 45μm sieve, and sample toner 2
Put g into the upper sieve, amplitude scale 1mm, vibration time 30
After vibrating under the condition of sec, it is calculated according to the following calculation formula. (Powder weight remaining on the upper sieve / sampled amount) × 100 (a) (Powder weight remaining on the middle sieve / sampled amount) × 100 × (3/5) (b) (Remained on the lower sieve Powder weight / sample amount) × 100 × (1/5) (c) Aggregation degree (%) = (a) + (b) + (c)

The degree of aggregation calculated by the above method is 1
If less than 0% of toner is used in the replenishing method, a large amount of toner is replenished because the fluidity of the toner is too high even if the number of rotations of the hopper (toner replenishing container) is made small. Ground fog is likely to occur. On the other hand, when the cohesion exceeds 30%, the fluidity of the toner is too low, so that the toner replenishment amount tends to vary, and when the toner replenishment amount is small, the problem of image density reduction tends to occur.

FIG. 1 is a schematic representation of an apparatus useful in practicing the method of the present invention. When a toner replenishment signal is output from a density sensor (not shown), the motor 106 rotates and the drive gear 105 moves, whereby the cartridge (toner replenishment container) 1 rotates and the replenishment toner is developed from the tip of the cartridge 1. It is supplied into the container 201. In this apparatus, a density sensor is provided in the developing device 201, and a means for detecting the insufficient amount of toner in the developing device 201 by the function of the density sensor is adopted. In the figure,
Reference numeral 2 is a cap, 3 is a rib portion, 4 is a ring cap, 5 is a seal, 101 is a cartridge receiving stand, 102 is a shutter plate, 103 is an agitator 202, and a toner supply roller.

As the binder resin of the toner used in the present invention, the energy which can be used for fixing is decreasing due to the recent energy-saving fixing and the increase of copying speed, and the fixing temperature is low, that is, so-called low temperature fixing. It is preferable to use a polyester resin useful as a toner. As the polyester resin, one having Tg of 65 to 75 ° C. is used. When Tg is 65 ° C. or lower, the storage stability of the toner deteriorates, and when Tg is 75 ° C. or higher, the low temperature fixability of the toner deteriorates. Further, it is preferable that the ratio of the polyester resin to the whole binder resin is large, and the effect of the present invention cannot be remarkably obtained when it is 50 parts by weight or less.

In the present invention, in addition to the polyester resin, other resins may be added within the range of 0 to 50 parts by weight. Examples of other resins include polystyrene, chloropolystyrene, poly-α-stillstyrene, styrene-
Chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene-maleic acid copolymer, styrene-acrylic acid ester copolymer Polymers (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 copolymer (styrene-
Methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-phenyl methacrylate copolymer, etc.), styrene-α-chloromethyl acrylate copolymer, styrene- Acrylonitrile-styrene resin such as acrylic acid ester copolymer (a homopolymer or copolymer containing styrene or a styrene substituent), vinyl chloride resin, styrene-vinyl acetate copolymer, rosin-modified maleic acid resin,
There are phenyl resin, epoxy resin, low molecular weight polyethylene, low molecular weight polypropylene, ionomer resin, polyurethane resin, silicone resin, ketone resin, ethylene-ethyl acrylate copolymer, xylene resin, polyvinyl butyral resin, etc., but these resins are independent. Not limited to use, two or more kinds can be used in combination. Also, the production method thereof is not particularly limited, and any of bulk polymerization, solution polymerization, emulsion polymerization and suspension polymerization can be used.

As the wax component used in the present invention, conventionally known low molecular weight polypropylene or the like may be used, but since the melting temperature is relatively high, sufficient releasability cannot be obtained by low temperature fixing. In some cases, the acid value is 5
The following free fatty acid type carnauba wax is preferably used. Carnauba wax has a low melting temperature and exhibits sufficient releasability even at low temperature fixing. The carnauba wax used in the present invention is a natural wax composed of fatty acids and alcohols, which is obtained from leaves of plants of the family Palmaceae. In particular, carnauba wax used in the present invention is one in which free fatty acids are eliminated, and usually has an acid value of 3 to 10%, whereas
% Or less, the dispersibility in the binder resin becomes small, and the dispersibility is improved. The amount of carnauba wax added is 2 to 20 parts by weight, preferably 3 parts by weight, based on 100 parts by weight of the binder resin.
10 to 10 parts by weight.

The fluidity improver used in the present invention is, for example, JP-A-51-120631 and JP-A-48-47.
No. 346, No. 46-5782, No. 51-101535.
, Silica, titanium oxide,
Although an inorganic fine powder such as aluminum oxide can be used, generally, the low-temperature fixing toner has poor fluidity due to the adhesive property of the resin or wax. In order to improve the fluidity of the low temperature fixing toner containing the wax component as in the present invention, the addition of silica is extremely useful. As the silica fine powder used in the present invention, all conventional products synthesized by a wet method, a dry method or the like can be used, but a dry method having a small primary particle size and a large fluidity modifying effect is particularly useful. The amount of the fine silica powder added to the toner is 0.2 to 100 parts by weight of the toner excluding the fine silica powder.
It is desirable to use 1.0 part by weight. If it is 0.2 or less, the cohesion degree of the toner becomes too large, and if it is 1.0 or more, the cohesion degree becomes too small, and proper toner replenishment may not be possible.

Further, as described above, the toner used in the present invention preferably has a volume average particle diameter in the range of 5 to 10 μm in order to improve image quality. Therefore, in the present invention, the ratio of 5 μm or less in the toner is 30 to 6 in terms of number.
It is desirable to set it within the range of 0%. If the ratio of the toner amount of 5 μm or less is 30% or less, sufficient image quality cannot be obtained, and if it is 60% or more, the toner cohesion becomes too large, and the toner replenishment amount tends to vary, and the replenishment amount is small. In this case, the problem of image density reduction is likely to occur. The COULTER COUNTER MODEL is used for the measurement when the volume average particle diameter of the toner is 5 μm or less and the amount of fine powder is small.
TAII (COULTER ELECTRONICS
LTD) can be used.

The polyester resin used in the present invention is
Obtained by polycondensation of alcohol and carboxylic acid.
Examples of the alcohol used include diols such as ethylene glycol, diethylene glycol, triethylene glycol and propylene glycol: 1,4-
Etherified bisphenols such as bis (hydroxymethyl) cyclohexane and bisphenol A: other dihydric alcohol monomers and trihydric or higher polyhydric alcohol monomers. Examples of the carboxylic acid include divalent organic acid monomers such as maleic acid, fumaric acid, phthalic acid, isophthalic acid, terephthalic acid, succinic acid and malonic acid: 1,2,4-benzenetricarboxylic acid,
1,2,5-benzenetricarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methylene Examples thereof include trivalent or higher polyvalent carboxylic acid monomers such as carboxypropane and 1,2,7,8-octanetetracarboxylic acid.

In the toner of the present invention, various colorants can be used if necessary. For example, carbon black, lamp black, iron black, aniline blue, phthalocyanine blue, phthalocyanine green, Hansa yellow G, rhodamine 6G lake, calco oil blue, chrome yellow, quinacridone, benzidine yellow, rose bengal, triallylmethane dyes, etc. Any known dyes and pigments can be used alone or in combination. The amount of these colorants used is 1 to 100 parts by weight of the binder resin.
30 parts by weight, preferably 3 to 20 parts by weight.

Various polarity control agents can be used in the toner of the present invention, if necessary. When the electrostatic latent image formed on the photoconductor has a negative polarity, the positive polarity toner is used, but when the reversal development is performed, the negative polarity toner is used. As the positive polarity controlling agent, nigrosine derivatives, metal salts, alkoxylated amines, quaternary ammonium salts, alkylamides, etc. can be used. Further, as the negative polarity controlling agent, a metal complex salt type dye, a salicylic acid derivative metal salt or the like can be used. The amount of these polarity control agents used is 0.1 to 5.0 parts by weight, preferably 0.2 to 2.0 parts by weight, based on 100 parts by weight of the binder resin.

The method for producing the toner of the present invention may be a conventionally known method, for example, a polyester resin, other binder resin, a wax component, a colorant, a polarity control agent and the like are melt-kneaded by a kneader such as a hot roll or an extruder. After that, it solidifies by cooling,
This is crushed with a crusher such as a jet mill or an I-type mill, and the volume average particle diameter is 5 to 10 μm and 5 μm or less.
It can be obtained by classifying into%.

A method of adding a fluidity improver to the toner of the present invention may be a conventionally known method, for example, a device such as a Henschel mixer or a speed kneader may be used for mixing.

The toner of the present invention is used as a mixture with a carrier. As the carrier, any conventionally known carrier may be used, and uncoated carriers such as iron powder and ferrite, carriers coated with styrene-acrylic copolymer resin, silicone resin, fluorine-modified acrylic resin, resin binder type carriers and the like can be used. .

[0026]

The present invention will be described below with reference to specific examples.
The present invention is not limited to these. The parts here are based on weight.

Example 1 Polyester resin (Tg = 60 ° C.) 65 parts Styrene-butyl acrylate copolymer 35 parts (Tg = 67 ° C., toluene-insoluble matter 0%) Free fatty acid type carnauba wax (acid value = 6. 2) 4 parts Carbon black (# 44 manufactured by Mitsubishi Carbon Co., Ltd.) 4 parts A mixture consisting of 1 part quaternary ammonium salt was thoroughly mixed and stirred in a Henschel mixer, and then about 30 at a temperature of 130 to 140 ° C. in a roll mill.
After heat-melting for 1 minute and cooling to room temperature, the obtained kneaded product was pulverized and classified to obtain a toner having a volume average particle size of 12.3 μm and a ratio of 5 μm or less of 65% in number conversion. To 100 parts of this toner, 0.4 part of titanium oxide was sufficiently mixed and kneaded with a speed kneader to obtain a toner. The aggregation degree of the obtained toner was measured and found to be 23%. A two-component developer obtained by mixing the toner obtained as described above and a carrier is supplied to a developing device of a copying machine manufactured by Ricoh Co., which has a replenishment method in which a toner replenishment hopper is horizontally installed and the toner is revolved to rotate. Inserting and replenishing toner only from the hopper, continuous copying is performed, initial image 10,000 sheets, 30,000 sheets,
The image density and background fog of 50,000 sheets and 100,000 sheets were examined.
The results are summarized in Table 1.

Example 2 Polyester resin (Tg = 70 ° C.) 65 parts Styrene-butyl acrylate copolymer 35 parts (Tg = 67 ° C., toluene insoluble content 0%) Free fatty acid type carnauba wax released (acid value = 6. 2) Toner obtained in the same manner as in Example 1 using a mixture consisting of 4 parts carbon black (# 44 manufactured by Mitsubishi Carbon Co., Ltd.) 4 parts 1 part quaternary ammonium salt (volume average particle size = 11.7 μm, 5 μm The following ratios were 63% in terms of number, cohesion degree = 21%) and the developer was set in the same copying machine, and only the toner was stored in the toner supply container and the same evaluation was performed. The results are summarized in Table 1.

Example 3 Polyester resin (Tg = 60 ° C.) 65 parts Styrene-butyl acrylate copolymer 35 parts (Tg = 67 ° C., toluene insoluble content 0%) Free fatty acid type carnauba wax (acid value = 3. 2) 4 parts Carbon black (# 44 manufactured by Mitsubishi Carbon Co., Ltd.) 4 parts Toner obtained in the same manner as in Example 1 using a mixture of quaternary ammonium salt (volume average particle size = 11.5 μm, 5 μm or less) The ratio was 65% in terms of number, the cohesion degree = 24%), the developer was set in the same copying machine, and only the toner was stored in the toner supply container, and the same evaluation was performed. The results are shown in Table 1.

Example 4 Polyester resin (Tg = 60 ° C.) 65 parts Styrene-butyl acrylate copolymer 35 parts (Tg = 67 ° C., toluene insoluble content 0%) Free fatty acid type carnauba wax (acid value = 6. 1) 4 parts Carbon black (# 44 manufactured by Mitsubishi Carbon Co., Ltd.) 4 parts 4 parts quaternary ammonium salt 1 part Using a mixture obtained in the same manner as in Example 1, a fluidity improver-free toner (volume average particle size = 12.5 μm
Then, 0.4 part of hydrophobic colloidal silica was sufficiently mixed and stirred with a speed kneader to 100 parts of 100 parts of a ratio of 5 μm or less in terms of number) to obtain a toner. The degree of aggregation was measured and found to be 13%. The toner and the developer obtained by mixing the toner and the carrier were set in the same copying machine as in Example 1, and only the toner was stored in the toner supply container and the same evaluation was performed. The results are summarized in Table 1.

Example 5 Polyester resin (Tg = 60 ° C.) 65 parts Styrene-butyl acrylate copolymer 35 parts (Tg = 67 ° C., toluene insoluble content 0%) Free fatty acid type carnauba wax (acid value = 6. 2) Toner obtained in the same manner as in Example 1 using a mixture consisting of 4 parts carbon black (# 44 manufactured by Mitsubishi Carbon Co., Ltd.) 4 parts 1 part quaternary ammonium salt (volume average particle size = 7.5 μm, 5 μm The following ratios were 63% in terms of number, cohesion degree = 20%) and the developer was set in the same copying machine, and only the toner was stored in the toner supply container and the same evaluation was performed. The results are summarized in Table 1.

Example 6 Polyester resin (Tg = 60 ° C.) 65 parts Styrene-butyl acrylate copolymer 35 parts (Tg = 67 ° C., toluene insoluble content 0%) Free fatty acid-type carnauba wax (acid value = 6. 2) Toner obtained in the same manner as in Example 1 using a mixture consisting of 4 parts carbon black (# 44 manufactured by Mitsubishi Carbon Co., Ltd.) 4 parts 1 part quaternary ammonium salt (volume average particle size = 11.7 μm, 5 μm The following ratios were 53% in terms of number, cohesion degree = 21%) and the developer was set in the same copying machine, and only the toner was stored in the toner supply container and the same evaluation was performed. The results are summarized in Table 1.

Comparative Example 1 Toner obtained in the same manner as in Example 1 except that the carnauba wax of Example 1 was changed from 4 parts to 8 parts (volume average particle size = 12.7 μm, ratio of 5 μm or less). Was 67% in terms of number, aggregation degree = 37%) and the developer was set in the same copying machine and the same evaluation was performed. The results are summarized in Table 1.

Comparative Example 2 A toner obtained in the same manner as in Example 4 except that the carnauba wax of Example 4 was changed from 4 parts to 0 part (volume average particle size = 12.2 μm and 5 μm or less). The ratio was 60% in terms of number, the agglomeration concentration = 7%) and the developer was set in the same copying machine and the same evaluation was performed.

The above results are shown in Table 1.

[Table 1]

By using the toner replenishing method of the present invention, the conventional problems in the replenishing method using the toner replenishing hopper horizontally installed in the copying machine are improved, and the background fog due to the fluctuation of the toner concentration is caused even in the continuous copying. It is possible to maintain high image quality without causing image quality deterioration such as image density reduction.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an apparatus useful for carrying out the method of the present invention.

[Explanation of symbols]

 1 Toner Supply Container 2 Cap 3 Rib Part 4 Ring Cap 5 Seal 101 Cartridge Stand 102 Shutter Plate 103 Agitator 105 Drive Gear 106 Motor 201 Developer 202 Toner Supply Roller

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication location G03G 9/087 (72) Inventor Tomoe Hagiwara No. 3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Tomio Kondo 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd.

Claims (2)

[Claims] 1. A method for detecting a shortage amount of toner in a developing device accommodating a dry two-component developer and supplying toner to the developing device based on this detection, in a horizontally installed toner supply container. Is filled with toner having a cohesion degree of 10 to 30%, the toner supply container is rotationally driven, and the number of rotations is controlled according to the insufficient amount of toner in the developing device.
A toner replenishing method in a dry two-component developer, characterized in that the toner corresponding to the deficient amount is supplied into the developing device from the tip of the toner replenishing container. 2. The toner replenishing method for a dry two-component developer according to claim 1, wherein a cartridge type container is used as the toner replenishing container.