JP2704784B2 - Negatively chargeable non-magnetic toner and image forming method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a negatively chargeable non-magnetic toner in electrophotography and an image forming method.

[Related Art] Conventionally, a corona discharger has been known as a charging unit in an electrophotographic apparatus or the like. However, corona dischargers have problems such as the need to apply a high voltage and the generation of a large amount of ozone.

Therefore, recently, the use of contact charging means without using a corona discharger has been studied. Specifically, a voltage is applied to a conductive roller serving as a charging member, and the roller is brought into contact with a photosensitive member serving as a member to be charged to charge the surface of the photosensitive member to a predetermined potential. If such a contact charging means is used, a lower voltage can be achieved as compared with a corona discharger,
Ozone generation is also reduced.

For example, Japanese Patent Publication No. Sho 50-13661 discloses that a low voltage can be applied when charging a photoreceptor by using a roller having a core covered with a dielectric made of nylon or polyurethane rubber. However, in the above conventional example, when the core metal is coated with nylon, it is not possible to maintain sufficient contact with the member to be charged because there is no elasticity such as rubber.
Poor charging may occur. On the other hand, when the core metal is coated with polyurethane rubber, the softening agent impregnated in the rubber-based material exudes, and when the photoreceptor is used as the charged body, the charging member sticks to the photoreceptor when the photoreceptor stops at the contact portion. Or the area may cause image blurring. Also, when the softening agent in the rubber material of the charging member exudes and adheres to the surface of the photoreceptor, the resistance of the photoreceptor decreases, causing image deletion, and in severe cases, becomes unusable or remains on the surface of the photoreceptor. In some cases, the toner adheres to the surface of the charging member, causing a filming phenomenon. When a large amount of toner adheres to the surface of the charging member, the surface of the charging member is insulated, the charging ability of the charging member is lost, the charging of the surface of the photoreceptor becomes nonuniform, and the image is adversely affected.

On the other hand, when the developing process using the non-magnetic color toner is combined, various problems occur in addition. In many cases, the toner does not contain a magnetic substance and does not contain a conductive substance such as carbon black from the viewpoint of color saturation. For this reason, there is no portion where the charge leaks particularly under low temperature and low humidity, and the charge tends to be excessively large as compared with the normal toner.

In addition, a full-color toner often uses a polyester resin as a binder resin depending on conditions such as fixing properties, color mixing properties, and transparency, but a toner made of a polyester resin is generally easily affected by temperature and humidity. In particular, problems such as an excessive charge amount under low humidity and an insufficient charge amount under high humidity are particularly likely to occur.

Furthermore, for the purpose of improving various image characteristics such as resolution, density uniformity or fogging, external addition of silica fine powder to impart fluidity to the toner is widely performed. The conventional silica fine powder has a large charge amount under low humidity, which further promotes the above problem.

In recent years, there has been a strong demand for higher image quality of copying machine images. On the other hand, high image quality is achieved by reducing the particle size of the toner. However, even if the particle size of the toner is reduced, the surface area of the toner is increased, and the charge amount is likely to be excessive.

As described above, when the charging is excessive, the toner is difficult to be transferred from the photoreceptor, and the residual toner on the photoreceptor increases, so that the toner that cannot be collected in the cleaning process is likely to appear. Further, since the toner is strongly charged and adhered to the photoreceptor, defective cleaning is likely to occur. The toner that cannot be removed in these cleaning steps adheres to the charging member, causing a reduction in charging ability and filming of the photoconductor.

Also, if the particle size is small, there are many contact points between toners,
The fluidity of the toner deteriorates. Therefore, aggregation of toner occurs in the cleaning process, and cleaning failure occurs.

[Problems to be Solved by the Invention] The present invention has been made in view of the above points, and can sufficiently maintain the contact between a charging member and a member to be charged, and prevent the charging member from being fixed to the member to be charged. Further, the present invention is applied to an image forming method having a charging step for preventing a plasticizer contained in the conductive rubber of the charging member from adhering to the member to be charged, so that a high-resolution and high-definition image can be obtained, and a developing, transferring and cleaning step. After the process, the non-magnetic toner that remains on the member to be charged, and thus does not stick to the surface of the charging member or the surface of the member to be charged, and a developing process, a transfer process, and a cleaning using the toner It is an object of the present invention to provide an image forming method comprising the steps of:

[Means and Actions for Solving the Problems] The present invention relates to an insulating negatively chargeable non-magnetic toner comprising at least a non-magnetic colorant-containing resin particle and a fluidity improver, wherein the non-magnetic colorant-containing The resin particles contain a polyester resin having a diol component and a dicarboxylic acid component as main components, and a polyester resin in which at least a part of -COOH is substituted by a functional group containing N. One type is silica fine powder, which is treated with a silane coupling agent having a positive triboelectric charging site and a negative triboelectric charging site, and further treated with silicon oil, The toner has a volume average particle size of 6 to 10μ.
m, a negatively chargeable non-magnetic toner.

Further, the present invention includes a charging step of charging by contacting a charging member to which a voltage is applied from the outside with a member to be charged; a developing step of developing the member to be charged with toner; a transfer step; and a cleaning step. In the image forming method, the charging member has a conductive rubber layer, and a surface layer of a release coating on at least a portion outside the conductive rubber layer and in contact with the member to be charged. The toner is an insulating negatively chargeable non-magnetic toner having at least a non-magnetic colorant-containing resin particle and a fluidity improver, wherein the non-magnetic colorant-containing resin particle has a diol component as a constituent component. A polyester resin containing a dicarboxylic acid component as a main component and at least a part of -COOH substituted by a functional group containing N, and at least one of the fluidity improvers is a silica fine powder. The silica fine powder is treated with a silane coupling agent having a positive triboelectrification site and a negative triboelectrification site, and further processed with silicone oil. The present invention relates to an image forming method characterized by being in the range of 6 to 10 μm.

That is, the present inventors provide a charging step in which charging is performed by bringing a charging member to which a voltage is applied from the outside into contact with a member to be charged, wherein the charging member is a conductive rubber layer and the conductive rubber layer is located outside the conductive rubber layer. In adopting a charging step of applying a voltage from outside by contacting a charging member having a surface layer of a release film and a surface layer of a release coating on at least a portion in contact with the member to be charged, and performing charging. Negatively chargeable non-magnetic toner enables high-resolution, high-definition, and high-quality images, and the charge amount does not become excessive even at low humidity. It has been found that a toner satisfying the above object can be provided by defining a binder resin of the toner, adding a specific fluidity improver to the toner, and further defining a particle size distribution of the toner.

Hereinafter, the components and functions of the negatively chargeable nonmagnetic toner of the present invention will be described.

The present inventors have conducted intensive studies on the charging stability and the prevention of charge-up of the negatively chargeable non-magnetic toner. Has been found to achieve long-term charging stability in a wide range of environments.

That is, by replacing at least a part of -COOH with a functional group containing N, the toner is less likely to absorb moisture under high humidity, and at the same time, the effect of accelerating the rise of charging by rubbing with the functional group containing N Also occurs. As a result, a decrease in charging at high temperatures can be suppressed to some extent.

In general, the negative charge of a polyester resin tends to be excessive under low humidity. However, by treating this phenomenon with a modifier containing N, it is possible to appropriately charge the resin due to the positive charge ability of the modifier. It is neutralized, is very effective in suppressing charge-up, and has good cleaning properties.

Furthermore, in order to make the present invention more effective, the sum of the acid value and the hydroxyl value is 3 to 20 mgKOH / g, preferably 4 to 15 mgKOH / g.
When KOH / g is used, a toner having sufficient environmental stability of charging is achieved, which is desirable.

Replacing at least a part of the -COOH with a functional group containing N is disclosed in JP-A-61-14644 and the like, but these are intended only for a positively chargeable toner, and the invention is not limited thereto. This is an invention completely different from the above-mentioned toner.

JP-A-62-195676, JP-A-62-195678, JP-A-62-195676
According to JP-A-195680, JP-A-62-195681, JP-A-62-195682 and the like, it is stated that if the amount of terminal groups, especially the amount of carboxyl groups, is excessively reduced, the charge amount of the polyester resin is reduced. The inventor has found that the amount of charge takes a sufficient value by containing a suitable charge control agent which is preferable in forming a toner. Further, according to the above-mentioned publication, it is described that the ratio between the hydroxyl value and the acid value is adjusted to 1: 2 or more for the purpose of improving the fluidity and lowering the minimum fixing temperature. It has been found that stable fixing performance can be obtained because the use of an agent can achieve appropriate fluidity and an appropriate filling state of the toner layer on the transfer material.

Now, replacing at least a portion of the -COOH in the present invention a functional group containing N may be processed polyester polymerization reaction modifier having a functional group NH _2, NHR, NR _2, etc. which are reactive with -COOH Good.

Examples of the polyhydric alcohol component of the polyester resin used in the present invention include ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, diethylene glycol, dipropylene glycol, and tripropylene glycol. Ethylene glycol, 1,5
-Pentanediol, 1,6-hexanediol, neopentene glycol, pentaerythritol diallyl ether, trimethylene glycol, 2-ethyl-1,3-hexanediol, hydrogenated bisphenol A, and a bisphenol derivative represented by the following formula; (Where R is an ethylene or propylene group, x and y are each an integer of 1 or more, and the average value of x + y is 2 to 2)
It is 10. ) And the like.

As the dicarboxylic acid component, fumaric acid, maleic acid, citraconic acid, unsaturated dicarboxylic acids such as itaconic acid, or acid anhydrides thereof, succinic acid, adipic acid, sebacic acid, dicarboxylic acids such as azelaic acid or these Anhydrides, aromatic phthalic dicarboxylic acids such as phthalic acid and terephthalic acid.

As the diol component used in the present invention, 40-60mo
It is desirable that the amount is 1%, preferably 45 to 55 mol%, and the dicarboxylic acid component is 60 to 40 mol%, preferably 55 to 45 mol%.

Examples of the N-containing modifier used in the present invention include diethanolamine, dimethylamineethanol, triethanolamine, polyalkyleneamine, diethylenetriamine, and triethylenetetramine.

Next, a method for producing such a polyester resin will be described. In an inert gas atmosphere (under nitrogen gas often) normal pressure to reduced pressure (0~-760mmH ₂ O), with stirring
The temperature is raised to 60 to 270 ° C, preferably 80 to 220 ° C, and the reaction is carried out for 10 to 30 hours. Water or alcohols produced by the condensation polymerization are continuously discharged to the outside of the system together with the inert gas while supplying the inert gas into the system, so that the condensation polymerization proceeds. For example, an acid and an alcohol are charged into a reactor equipped with a stirrer, a condenser, a thermometer and an inert gas introduction tube.
Next, gas replacement is performed by introducing an inert gas. After the gas replacement is completed, the inert gas is kept flowing, the reaction temperature is raised to a predetermined temperature, and the condensation polymerization reaction is performed with stirring for 10 to 30 hours. Water or alcohol generated by the condensation polymerization reaction is aggregated and collected by a condenser outside the system. At the end of the reaction, a modifier is added to treat the -COOH group.

After the completion of the reaction, the generated water or the residual alcohol in the case where the added alcohol is excessive is evaporated under reduced pressure and aggregated and collected by a condenser outside the system. Thereafter, the temperature is lowered to room temperature to obtain a polyester resin.

Here, the polyester resin according to the present invention is, by its nature, preferably the total of the acid value and the hydroxyl value is 3 to 20 mgKOH / g, and if it exceeds 20 mgKOH / g, the carboxyl group or hydroxyl value increases, The environment dependence of charging increases, and the restrictions on usable coloring agents, external additives, and the like increase.

On the other hand, if it is less than 3 mgKOH / g, the dispersion in the resin is likely to be non-uniform, and there is a possibility that toner scattering and fogging may occur.

As described above, by using the above polyester resin, it is possible to suppress the decrease in charge under high humidity while satisfying the fixing property, color mixing property, and transparency required for a full-color toner, and to charge even under low humidity. A toner whose amount does not become excessive can be obtained.

However, usually, for the purpose of improving various image characteristics such as resolution, density uniformity or fog,
Usually, negatively chargeable silica fine powder is externally added to impart fluidity to the toner.However, the conventional negatively chargeable silica fine powder has a large charge amount especially under low humidity. However, there is a problem that the environmental stability is deteriorated due to the external addition.

Until now, in order to obtain a toner having good environmental stability, the conventional idea was to suppress the water absorption of silica and to stabilize the triboelectric charge of silica itself. Such an example is disclosed in JP-A-49-42354 for treating silica with silicone oil, and Japanese Patent Publication No. 54-16219 for externally adding hydrophobic silica to a toner.
JP-A-56-123550 discloses a method of externally adding silica treated with a silane coupling agent to a toner. Thus, previous developments focused solely on treating agents and treatments for hydrophobizing silica.

The present inventors have confirmed that one of the causes of the environmental instability of the toner is due to environmental fluctuation of the triboelectric charge amount of the toner.
The degree of the environmental change in the triboelectric charge amount of the toner varies depending on the type of the toner carrier such as a carrier or a sleeve, but silica also has a considerable effect.
Moreover, even if the above polyester resin is used, the triboelectric charge of silica itself does not depend on the environment because the triboelectric charge varies depending on the environment. It is not enough that there is no environmental change, and it is necessary to make the change so as to cancel the change of the toner not externally added with silica. Further, silica having a high absolute value of the triboelectric charge is not preferable from the viewpoint of stabilizing the environment of the toner. Here, the silica having a high triboelectric charge means the triboelectric charge with iron powder (EFV200 / 300 made by Nippon Iron Powder) measured by the blow-off method at a silica / iron powder ratio of 2: 100.
-150 | μc / g or more.

The present inventors have newly found the above findings, and have developed silica having a low frictional charging property and a frictional charging amount decreases as the humidity decreases. As a result of diligent studies, after treating the silica fine powder with a silane coupling agent having both a positive triboelectrification site and a negative triboelectrification site, and further processing with silicon oil, the lower the triboelectricity and the lower the humidity The inventors have found that silica having a reduced triboelectric charge can be obtained, and have completed the present invention.

As the silica fine powder of the present invention before the silica fine powder is treated with the silane coupling agent, both dry silica and wet silica can be used. Silica is preferred.

The dry method referred to herein is a method for producing silica fine powder generated by vapor phase oxidation of a silicon halide derivative. For example, in a method utilizing the thermal decomposition oxidation reaction of silicon tetrachloride gas in oxygen-hydrogen, the basic reaction formula is as follows.

SiCl ₄ + 2H ₂ + O ₂ → SiO ₂ + 4HCl Also, in this manufacturing process, by using another metal halogen derivative such as aluminum chloride or titanium chloride together with a silicon halide derivative, a composite fine powder of silica and another metal oxide is obtained. It is also possible and includes these.

On the other hand, as a method for producing the silica fine powder used in the present invention by a wet method, various conventionally known methods can be applied. For example, decomposition of sodium silicate with an acid, given by a general reaction formula (hereinafter, the reaction formula is abbreviated), Na ₂ O · XSiO ₂ + HCl + H ₂ O → SiO ₂ · nH ₂ O + NaCl, etc., and ammonium salts or alkali salts of silicon sodium , An alkaline earth metal silicate is produced from sodium silicate, then decomposed with acid to form silicic acid, a sodium silicate solution is converted to silicic acid with ion exchange resin, natural silicic acid or silicic acid There is a method using an acid salt.

Silica such as aluminum silicate, sodium silicate, potassium silicate, magnesium silicate, zinc silicate, etc. can be applied to the silica fine powder here, in addition to anhydrous silicon dioxide (silica).

Among the above silica fine powders, those having a specific surface area of 30 m ² / g or more (particularly 50 to 400 m ² / g) measured by the BET method by nitrogen adsorption give good results.

Examples of the organic group that can be a positive triboelectrification site of the silane coupling agent include an amino group and a nitrogen-containing heterocyclic group. As the nitrogen-containing heterocyclic group, there are an unsaturated heterocyclic group and a saturated heterocyclic group, each of which can be applied.
Examples of the compound having an unsaturated heterocyclic group include the following.

Examples of the compound having a saturated heterocyclic group include the following.

Also, nitrogen-containing salt compounds such as quaternary ammonium salts and pyridinium salts can be exemplified. Further, phosphines, phosphonium salts and the like can be exemplified. However, ease of synthesis,
Considering the price, an amino group and a nitrogen-containing heterocyclic group are preferred.

Various organic groups can be exemplified as the organic group that can serve as the negative triboelectrification site of the silane coupling agent. For example, conventional silane coupling agents whose organic groups do not have nitrogen or phosphorus are negatively triboelectrically chargeable. This is considered to be due to the Si—C bond, but it is very preferable to use this as a negative triboelectric charging site. However, in this case, the negative triboelectricity due to the Si-C bond decreases with an increase in the carbon number of the hydrocarbon directly bonded to Si,
In the case of the present invention, those having 3 or more carbon atoms cannot be used. Preferably, it has 2 or less carbon atoms.

In addition, an organic acid such as carboxylic acid or sulfonic acid, or an organo group having an acidic hydroxy group such as phenol can be used to positively provide a negative triboelectric charging site in the silane coupling agent.

Further, by using a halogen atom, a carbonyl group, a sulfonyl group, a cyano group, or the like, a negative triboelectric charging site can be provided in the silane coupling agent.

The silane coupling agent according to the present invention can be synthesized by a conventionally known method. Basically, a hydrohalogenosilane or hydroalkoxysilane and a compound having an alkene portion into which the above-mentioned positive triboelectric charging site (if necessary, a negative triboelectric charging site) is introduced are allowed to act in the presence of a catalyst such as a platinum-containing compound. When utilizing a Si-C bond as the negative triboelectric charging site, it is not necessary to use a compound having an alkene portion into which a negative triboelectric charging site has been introduced. It is necessary to cause both the compound having the compound and the compound having an alkene moiety introduced with a negative triboelectric charge site to react with hydrohalogenosilane or hydroalkoxysilane. At this time, the order of the action of the compound having an alkene moiety into which a triboelectrically charged site is introduced may be positive or negative, or may be simultaneously applied. In addition, one of the compounds having an alkene moiety into which a positive or negative triboelectric charging site is introduced is reacted with hydrohalogenosilane or hydroalkoxysilane to obtain positive and negative two kinds of silane coupling agents, respectively. May be obtained to obtain the silane coupling agent according to the present invention.

Alternatively, a halogenoalkylalkoxysilane or a halogenoalkylhalogenosilane and a compound having the above-described positive triboelectric charging site (if necessary, a negative triboelectric charging site) may be allowed to act in the same manner as described above. For example, in the case of diethylaminopropyltriethoxysilane, triethoxyhydrosilane and allyldiethylamine are allowed to act in the presence of a chloroplatinic acid catalyst, or chloropropyltriethoxysilane and diethylamine are acted upon, and then sodium methoxide is further actuated for purification. Can be obtained.

Representative examples of the silane coupling agent according to the present invention are shown below, but they do not limit the present invention in any way.

1. Using a Si-C bond as a negatively charged part (1-3) H ₃ CNHCH ₂ Si (OCH ₃ ) ₃ 2. Those that use halogen, carbonyl, phenol, cyano group, etc. as negative triboelectric charging site 3. Using organic carboxylic acid derivative as negative triboelectric charging site 4. A product obtained by the action of a silane coupling agent having a negative triboelectric charging site and a silane coupling agent having a positive triboelectric charging site Silica treated with a silane coupling agent as described above improves the environmental stability of the toner and provides good fluidity and transferability. However, by further treating this silica with silicone oil, it becomes even more resistant to moisture. , Fluidity, and transferability can be improved. That is, the silicone oil treatment can increase the moisture resistance and improve the slipperiness of the silica, so that the fluidity of the toner can be increased and the transferability from the photosensitive drum can be further improved.

The silicone oil used in the present invention is generally represented by the following formula.

R: C _1-3 alkyl group R ′: Silicon oil modified group such as alkyl, halogen-modified alkyl, phenyl, modified phenyl R ″: C _1-3 alkyl group or alkoxyl group For example, dimethyl silicone oil, alkyl-modified silicon Oil, α-methylstyrene modified silicone oil,
Chlorphenyl silicone oil, fluorine-modified silicone oil and the like can be mentioned. Further, as the above-mentioned silicon oil, one having a clay at 25 ° C. of about 50 to 1000 centistokes is preferably used. Silicone oil having a molecular weight that is too low may generate volatile components due to heat treatment or the like, and if the molecular weight is too high, the viscosity becomes too high and the processing operation becomes difficult.

A known technique is used for the method of treating the silicone oil. For example, the silica fine powder treated with the silane coupling agent and the silicone oil may be directly mixed using a mixer such as a Henschel mixer, or silica may be used. It may be formed by spraying silicon oil on fine powder, or by dissolving or dispersing silicon oil in a suitable solvent, mixing with silica fine powder, and removing the solvent.

The degree of hydrophobicity of the silica fine powder according to the present invention is desirably 90% or more (preferably 95% or more). If the degree of hydrophobicity falls below this, high-quality images cannot be obtained due to moisture adsorption of the silica fine powder under high humidity.

The processing amount of the silicon oil may be a small amount because the silica fine powder is tentatively hydrophobized in the previous stage. A / 25 ± A / 30 parts by weight (A: specific surface area of the silica fine powder), more preferably A / 25 ±
A / 40 parts by weight is desirable. Here, the specific surface area of the silica fine powder is a value determined from the N ₂ adsorption at the BET method.

The reason for limiting the treatment amount is that if the amount of the silicon oil treatment is too small, the same result as that of the treatment with the silane coupling agent alone is obtained, and further improvement cannot be achieved. On the other hand, if the amount of the processed silicon oil is too large, the above-mentioned aggregates of the silica fine powder are likely to be formed, and extremely free silicon oil is formed. Therefore, when applied to a developer, the flowability is improved. Disadvantages such as the inability to perform

The amount of the silica fine powder used in the present invention is 0.01 to 5%, preferably 0.05 to 2%, based on the weight of the toner.
It is. Further, the silicas used in the present invention may be used together or some known silicas may be used in combination.

In the production of the toner of the present invention, the components are thoroughly kneaded by a hot kneader such as a hot roll, a kneader, an extruder, and then mechanically pulverized and classified. Or a method of obtaining a toner by dispersing such materials and spray-drying, or by mixing a predetermined material with a monomer to constitute a binder resin and then polymerizing this emulsion suspension to obtain a toner. Each method such as a toner manufacturing method can be applied.

Next, a preferred particle size distribution of the negatively chargeable non-magnetic toner of the present invention will be described. In the following description regarding the particle size distribution of the toner, “non-magnetic colorant-containing resin particles” are referred to as “toner particles”.

In the present invention, the negatively-chargeable non-magnetic toner has a volume average particle diameter in the range of 6 to 10 μm, contains 15 to 40% by number of toner particles having a particle diameter of 5 μm or less, and has a volume average particle diameter of 12.7 to 16.0 μm.
0.1 to 5.0% by volume of toner particles having a particle size of m
A toner particle having a particle size of 6.35 to 10.1 μm containing toner particles having a particle size of 16 μm or more and 1.0% by volume or less is represented by the following formula: The effect is more pronounced when having a particle size distribution that satisfies

The toner having the above particle size distribution can faithfully reproduce a latent image formed on the photoreceptor, and is excellent in reproducing a minute dot latent image such as a halftone dot and a digital image. Image with excellent gradation and resolution. Furthermore, high image quality can be maintained even when copying or printing out is continued, and even in the case of high density images, good development can be performed with less toner consumption than conventional non-magnetic toner. It also has advantages in terms of performance and miniaturization of the copier or printer body.

The reason why such an effect is obtained in the toner of the present invention is not necessarily clear, but is presumed as follows.

Conventionally, toner particles having a particle size of 5 μm or less
It is considered difficult to control the charge amount, impair the fluidity of the toner, and actively reduce it as a component that stains the machine by scattering toner and a component that causes image fogging. Had been. However, according to the study of the present inventors, it has been found that toner particles of about 5 μm are essential components for forming high quality image.

For example, using a two-component developer having a non-magnetic toner having a particle size distribution ranging from 0.5 μm to 30 μm and a carrier, the surface potential on the photosensitive member is changed, and a large development potential contrast is obtained in which a large number of toner particles are easily developed. , From halftone to halftone, and further to the latent image of small minute dots where only a few toner particles are developed, develops the latent image with the latent image potential changed on the photoconductor, and develops the toner particles on the photoconductor Was collected and the toner particle distribution was measured.
It was found that the following toner particles were large, and in particular, toner particles of about 5 μm were large on the latent image of fine dots. That is, 5
When the toner particles having a particle size of about μm are smoothly supplied to the development of the latent image on the photoreceptor, the image is faithful to the latent image and does not protrude from the latent image, and an image with truly excellent reproducibility can be obtained. It is.

Further, the toner particles of 12.7 μm to 16.0 μm are related to the necessity of the existence of toner particles having a particle size of about 5 μm.
Non-magnetic toner particles having a particle size of m or less certainly have the ability to faithfully reproduce the latent image of fine dots, but themselves have considerably high cohesiveness, which may impair the fluidity of the toner.

The present inventors have aimed at further improving the fluidity by adding the above-mentioned silica fine powder for the purpose of improving the fluidity, but alone, the image density, toner scattering,
It was confirmed that the conditions for satisfying all items such as fog were very narrow. Therefore, the present inventors have further studied the particle size distribution of the toner, and found that the toner particles having a particle size of 5 μm or less contained 15 to 40% by number,
It has been found that the flowability can be further improved and high image quality can be achieved by containing 0.1 to 5.0% by volume of 16.0 μm toner particles. That is, it is considered that the toner particles having a size in the range of 12.7 to 16.0 μm have a moderately controlled fluidity with respect to the toner particles having a size of 5 μm or less. A sharp image with excellent resolution and gradation is provided.

Further, for the toner particles of 6.35 to 10.1 μm, between the volume% (V), the number% (N) and the volume average particle size (v), It is further desirable that the toner of the present invention satisfies the following relationship.

The present inventors have studied the state of the particle size distribution and the development characteristics and found that there is a state of existence of the particle size distribution most suitable for achieving the object as shown by the above formula.

In other words, when the particle size distribution is adjusted by general air classification, the above value is large, which means that toner particles of about 5 μm that faithfully reproduce a minute dot latent image increase, and that the above value is small. It is understood that this indicates that toner particles of about 5 μm are reduced.

Therefore, when v is in the range of 6 to 10 μm and the above relational expression is further satisfied, good toner fluidity and faithful latent image reproducibility are achieved.

For toner particles having a particle size of 16 μm or more, 1.
It is preferable that the content is 0 volume% or less and the amount is as small as possible.

The configuration of the present invention will be described in more detail. 5 μm
The number of toner particles having the following particle size is preferably 14 to 15% by number of the total number of particles, and more preferably 20 to 35% by number.
When the number of toner particles having a particle diameter of 5 μm or less is less than 15% by number, the amount of non-magnetic toner particles effective for high image quality is small.
As the toner is used by continuing to copy or print out, the effective toner particle component decreases,
The balance of the particle size distribution of the toner deteriorates, and the image quality gradually decreases. On the other hand, if it exceeds 40% by number, toner particles are likely to aggregate with each other, resulting in a toner mass larger than the original particle size, resulting in rough image quality, reduced resolution, or an edge portion of the latent image. The density difference from the inside becomes large, and the image tends to be slightly hollow.

Further, the particle size in the range of 12.7 to 16.0 μm is preferably 0.1 to 5.0% by volume, and more preferably 0.2 to 3.0% by volume. Five.
If the content is more than 0% by volume, the image quality is deteriorated, and the development is performed more than necessary, that is, the toner is excessively applied, which causes an increase in toner consumption. On the other hand, when the content is less than 0.1% by volume, the image density is lowered due to the decrease in fluidity.

Further, the content of toner particles having a particle diameter of 16 μm or more is preferably 1.0% by volume or less, more preferably 0.6% by volume or less. Due to the existence of coarse toner particles of 16 μm or more protruding on the thin layer surface of the toner particles developed on the photoconductor, the delicate adhesion between the photoconductor and the transfer paper through the toner layer is irregular. As a matter of fact, it is likely to cause a change in transfer conditions and cause a transfer failure image. The volume average particle diameter of the toner is 6 to 10 μm, preferably 7 to 9 μm, and this value cannot be considered separately from the above-mentioned components.
If the volume average particle diameter is less than 6 μm, in applications having a high image area ratio such as a graphic image, there is a problem that the amount of toner applied on the transfer paper is small and the image density is low. This is considered to be due to the same reason as described above for lowering the density inside the edge portion of the latent image. If the volume average particle diameter is more than 10 μm, the resolution is not good, and if the use is continued at the beginning of copying, the image quality is liable to deteriorate.

As described above, by using this toner, a high-resolution, high-definition, high-quality copy image can be obtained, and the charge amount can be prevented from becoming excessive even under low humidity. As a result, the transfer efficiency is increased, the residual toner on the photoreceptor is reduced, and the adhesive force between the residual toner and the photoreceptor is reduced, so that cleaning failure and leakage from the cleaner can be prevented. In addition, since sufficient fluidity is obtained, aggregation in the cleaner is small, and poor cleaning due to toner aggregation can be prevented. Further, since a sufficient charge amount can be ensured even under low humidity, scattering and fogging do not occur.

As the coloring agent, known dyes and pigments, for example, phthalocyanine blue, induslen blue, peacock blue, permanent red, lake red, rhodamine lake, Hansa yellow, permanent yellow, benzidine yellow and the like can be used widely. The content thereof is 12 parts by weight or less, preferably 0.5 to 9 parts by weight, based on 100 parts by weight of the binder resin so as to be sensitive to the light transmittance of the OHP film.

The toner according to the present invention may contain a charge control agent for stabilizing the charge characteristics. At that time, a colorless or light-colored charge control agent that does not affect the color tone of the toner is preferable.
In the present invention, when used as a negatively chargeable non-magnetic toner, the present invention becomes more effective. In this case, as a negative charge controlling agent, for example, a metal complex of an alkyl-substituted salicylic acid (for example, di-tert-butyl salicylic acid) is used. Organometallic complexes such as chromium complexes or zinc complexes).
When compounding the negative charge control agent with the toner, the binder resin 100
It is preferable to add 0.1 to 10 parts by weight, preferably 0.5 to 8 parts by weight based on parts by weight.

The toner of the present invention can be used for both the one-component developing method and the two-component developing method. However, as a carrier when used as a two-component developer, an electrically insulating resin is used as a coating resin for a carrier core material. Is selected as appropriate depending on the toner material and carrier core material. In the present invention, at least one monomer selected from at least an acrylic acid (or an ester thereof) monomer and a methacrylic acid (or an ester thereof) monomer in order to improve the adhesion to the carrier core material surface. Must be contained. In particular, when a polyester resin particle having a high negative chargeability is used as a toner material, it is preferable to further form a copolymer with a styrene-based monomer for the purpose of stabilizing charging, and the copolymerization weight ratio of the styrene-based monomer is used. Is preferably 5 to 70% by weight.

The average molecular weight of the copolymer, the uniformity of the coating on the surface of the carrier core material, considering the coating strength, number average molecular weight of 10,0.
It is preferably from 00 to 35,000, preferably from 17,000 to 24,000, and the weight average molecular weight is from 25,000 to 100,000, preferably from 49,000 to 55,000.

As the monomer for the coating resin of the carrier core material that can be used in the present invention, examples of the styrene-based monomer include a styrene monomer, a chlorostyrene monomer, an α-methylstyrene monomer, and a styrene-chlorostyrene monomer. For example, acrylate monomers (methyl acrylate monomer, ethyl acrylate monomer, butyl acrylate monomer,
Octyl acrylate monomer, phenyl acrylate monomer, 2-ethylhexyl acrylate monomer) and the like, and methacrylate ester monomers (methyl methacrylate monomer, ethyl methacrylate monomer, butyl methacrylate monomer, phenyl methacrylate monomer).

As the magnetic particles used in the present invention, for example, surface oxidized or unoxidized iron, nickel, copper, zinc, cobalt,
Metals such as manganese, chromium, rare earths, and alloys or oxides thereof can be used. In addition, there is no particular limitation on the manufacturing method.

Next, the contact charging step of the present invention applicable to the image forming method will be specifically described.

The charging device in the present invention is, for example, as shown in FIG. Reference numeral 3 denotes a photosensitive drum which is a member to be charged, and rotates in the direction of the arrow. Reference numeral 4 denotes a charging roller which is a charging member brought into contact with the photosensitive drum 3 at a predetermined pressure.
E is a power supply unit that applies a voltage to the charging roller 4 and supplies a predetermined voltage to the metal core 4 a of the charging roller 4. In FIG. 2, E indicates a DC voltage, but may be obtained by superimposing an AC voltage on a DC voltage.

In the present invention, the conductive rubber layer 4b is provided on the metal cored bar 4a, and the surface layer 4c which is a release coating is provided on the peripheral surface. The reason is that a softening agent from the conductive rubber does not exude to a portion which comes into contact with the photoreceptor which is a charged member by providing a release coating outside the conductive rubber layer. Therefore, when the softener adheres to the photoreceptor, image flow due to lowering of the resistance of the photoreceptor and a decrease in charging ability due to filming of residual toner on the photoreceptor can be prevented, and a decrease in charging efficiency can be suppressed.

Furthermore, by using a conductive rubber layer for the charging roller, sufficient contact between the charging roller and the photoconductor can be maintained, and no charging failure occurs.

In the present invention, a charging device as shown in FIG. 2 can be used. Here, a blade-shaped contact charging member is used, but a metal supporting member 4 ′ to which a voltage is also supplied.
By supporting the conductive rubber 4'b with a, and providing a surface layer which is a release coating at a contact portion with the photosensitive drum 3, the same operation and effect as in the above example can be obtained.

In the above-described example, a roller-shaped or blade-shaped charging member is used. However, the present invention is not limited to this, and the present invention can be applied to other shapes.

Further, in the above-described example, the charging member is formed of the conductive rubber layer and the release coating, but the invention is not limited to this, and a high resistance is provided between the conductive rubber layer and the surface of the release coating to prevent leakage to the photoconductor. It is preferable to form a layer, for example, a hydrin rubber layer having small environmental fluctuation.

Nylon resins PVDF (polyvinylidene fluoride) and PVDC (polyvinylidene chloride) can be used for the release coating. Further, as the photoconductor, OPC, amorphous silicon, selenium, ZnO, or the like can be used. In particular, when amorphous silicon is used for the photoconductor, compared to the case where other materials are used, even if the softening agent of the conductive rubber layer adheres to the photoconductor even to a small extent, the image flow becomes severe, so The effect of the insulating coating is great. Further, the charging device of the present invention can be used for transfer.

Hereinafter, measurement methods (1) to (4) relating to the characteristic values of the toner used in the present invention will be described.

(1) Particle size distribution measurement Coulter counter TA-II type (manufactured by Coulter) is used as the measuring device, and an interface (manufactured by Nikkaki) that outputs a number average distribution and a volume average distribution and a CX-1 personal computer (manufactured by Canon) And the electrolyte is 1
Prepare a 1% aqueous NaCl solution using graded sodium chloride.

As a measurement method, 0.1 to 5 ml of a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant to 100 to 150 ml of the aqueous electrolytic solution, and 0.5 to 50 mg of a measurement sample is further added.

The electrolytic solution in which the sample was suspended was subjected to dispersion treatment for about 1 to 3 minutes using an ultrasonic disperser, and the Coulter Counter TA-II was used, using a 100 μm aperture as an aperture.
By measuring the particle size distribution of the particles of 2 to 40 μm, the volume average distribution,
Find the number average distribution.

From the obtained volume average distribution and number average distribution, values of volume average particle diameter, number average distribution of 5.04 μm or less, and volume average distribution of 16.0 μm or more are obtained.

(2) Measurement of Friction Charge Amount FIG. 3 is an explanatory view of a friction charge amount measuring device. First, a mixture of particles to be measured and iron powder particles EFV200 / 300 (manufactured by Powder Tech) is prepared. The mixing ratio is 2 parts by weight for 98 parts by weight of the magnetic particles in the case of the fluidity imparting agent.

The particles to be measured and the magnetic particles are placed in a measurement environment, left for 12 hours or more, then put into a polyethylene bottle, and mixed and stirred sufficiently.

Next, a mixture of particles and magnetic particles whose frictional charge is to be measured is placed in a metal measuring container 12 having a conductive screen 13 of 500 mesh (which can be appropriately deflected to a size that does not allow magnetic particles to pass) at the bottom. Then, a metal lid 14 is formed. The weight of the entire measurement container 12 at this time is defined as a scale W ₁ (g). next,
In the suction device 11 (at least the portion in contact with the measurement container 12 is at least an insulator), the pressure of the vacuum gauge 15 is adjusted to 250 mmAq by adjusting the air volume control valve 16 by suctioning from the suction port 17. In this state, suction is performed sufficiently (about 2 minutes) to remove the toner by suction. The potential of the electrometer 19 at this time is set to V (volt). Here, reference numeral 18 denotes a capacitor having a capacity of C (μF). The weight of the whole measurement container after suction is defined as a scale W ₂ (g). This triboelectric charge amount T (μC / g) is calculated as in the following equation.

(3) Hydrophobicity measurement 100 ml of pure water and 1 g of a sample are put in a tightly-sealed container, and shaken with a shaker for 10 minutes. After shaking, the silica powder layer and the aqueous layer were separated, and the aqueous layer was collected.The transmittance was measured at a wavelength of 500 mm with reference to pure water of a blank containing no silica fine powder, and the transmittance was measured. Is defined as the degree of hydrophobicity of the treated silica.

(4) Measurement of Acid Value and Hydroxyl Value The acid value is measured by weighing 2 to 10 g of a sample in a 200 to 300 ml Erlenmeyer flask and adding about 50 ml of a mixed solvent of methanol: toluene to 30:70 to dissolve the resin. If the solubility is poor, a small amount of acetone may be added. Using a mixed indicator of 0.1% bromthymol blue and phenol red, measure with a pre-standardized N / 10 potassium hydroxide-alcohol solution, and calculate the acid value from the consumption of the alcohol potassium solution by the following formula (I). Ask.

Acid value = KOH (ml number) × N × 56.1 / reagent weight (I) (where N is a factor of N / 10 KOH) In addition, the hydroxyl value is measured by using an excess of an actylating agent,
For example, acetylation is performed by heating with acetic anhydride, and the saponification value of the produced acetylated product is measured, and then calculated according to the following formula (II).

EXAMPLES Hereinafter, the present invention will be described in detail with reference to Examples. A charging device and a toner were prepared.

Charging device: The configuration shown in FIG. 1, and the outer diameter of the charging roller 4 is 12 mmφ
The conductive rubber layer 4b is EPDM, and the surface layer 4c is 10 μm thick.
Was used. The hardness of the charging roller 4 is 5
4.5 ゜ (ASKER-C).

Charging device: A charging roller having the same configuration as the charging device but having no surface layer 4c was used. Others are the same as the charging device.

<Example of resin production> The above compounds were mixed at a molar ratio of 1: 1 and placed in a four-necked round-bottomed flask equipped with a thermometer, a Teflon coating, a stirring blade, a glass nitrogen inlet tube, a condenser, and a decompression device. After introducing nitrogen gas from the glass inlet tube reaction vessel inert atmosphere, by adjusting the opening of the pressure reducing control valve and a nitrogen gas inlet valve, maintaining the system inside -750mmH ₂ O. Thereafter, the reactor was placed in a mantle heater and maintained at 170 ° C. to perform a condensation reaction for 20 hours. The pressure at this time was also kept at -750mmH ₂ O.

 This is designated as resin A.

Thereafter, acetic acid was added to the system, and diethanolamine was further added to the system to obtain a modified polyester resin B.

Separately, triethanolamine was added instead of diethanolamine to obtain a modified polyester resin C. Table 1 shows the acid value and the hydroxyl value of the resins A to C.

After sufficient premixing with a Henschel mixer,
The mixture was melt-kneaded at least twice with a three-roll mill, cooled, and coarsely ground to a particle size of about 1 to 2 mm using a hammer mill. Next, it was pulverized by a pulverizer using an air jet method. Further, the obtained finely pulverized product was classified to obtain colorant-containing resin particles.

Silica fine powder Aerosil 200 (manufactured by Nippon Aerosil Co., Ltd .: specific surface area 200 ±
100 parts by weight of 25 m ² / g) were treated with 20 parts by weight of the silane coupling agent shown in the compound example (1-1) (temperature: 150 ° C.,
After 2 hours), dimethyl silicone oil KF-96,1
Treatment was performed with 10 parts of 00cSt (manufactured by Shin-Etsu Chemical) diluted with a solvent, and 0.5% of silica fine powder which had been dried and then heat-treated at about 250 ° C. was externally added to obtain a cyan toner. The degree of hydrophobicity of the treated silica fine powder was 99.9%. The particle size distribution of this toner was as follows.

Toner: A toner was prepared in the same manner as the toner except that the resin A was used as the binder resin.

, Using a volume average particle size of 7.2 μm
Red powder was obtained. Silane cup shown in Compound Example (1-2) per 100 parts by weight of silica fine powder Aerosil 200 (manufactured by Nippon Aerosil Co., Ltd .: specific surface area 200 ± 25 m ² / g) in 100 parts of the above colorant-containing resin particles After processing 20 parts by weight of the ring agent (temperature: 150 ° C., time: 2 hours), the toner A is treated with 10 parts of dimethyl silicone oil KF-96,100 cSt (manufactured by Shin-Etsu Chemical).
0.5 part of silica fine powder treated in the same manner as described above was externally added to obtain a toner. The degree of hydrophobicity of this treated silica fine powder was 99.9%.

Toner: A toner was prepared in the same manner as the toner except that carbon black was used as the pigment.

Toner: A toner was prepared in the same manner as the toner, except that the fluidity improver was treated with dimethyldichlorofuran and negatively chargeable silica fine powder was used.

Except for Example 4 described below, 94 parts of Cu-Zn-Fe-based ferrite particles surface-coated with a styrene-acrylic acid-ethyl hexyl methacrylate copolymer were mixed with ~ 6 parts of these toners to prepare a developer. did.

Example 1 The charging device of a commercially available copier (CLC-500, manufactured by Canon) was modified to take the configuration shown below, and the contact pressure on the photoconductor was reduced to 50 g / cm.
The applied voltage is adjusted so that the development contrast is 290V at 23 ° C / 65%, 350V at 20 ° C / 10%, 250V at 30 ° C / 80%, and the developer using toner is injected. Image was drawn. As a result, the charging roller after the endurance was hardly stained, and no filming on the photoreceptor occurred. Further, even after the endurance, the decrease in the charging efficiency was very small as compared with before the endurance. During endurance, high-quality images with sufficient image density of 1.40 to 1.55 and no fog were obtained in each environment.

Example 2 A printing durability test was conducted in the same manner as in Example 1 using the charging step and the developer. As a result, the reduction in charging efficiency was small, and the charging roller was not stained and the photoconductor was not filmed.

Example 3 A printing durability test similar to that in Example 1 was performed using the above charging step and developer, and a high quality image having a sufficient image density was obtained. Also, no contamination of the charging roller and no filming of the photosensitive member occurred.

Example 4 The charging device of a commercially available copying machine (CLC-500, manufactured by Canon) was modified to take the configuration shown in Fig. 4, and the developing device was further modified so as to have the configuration shown in Fig. 4 with the following conditions. went. That is, in FIG. 4, reference numeral 22 denotes a sleeve formed by coating a phenol resin in which 40 parts by weight of molybdenum disulfide is dispersed on the surface of an aluminum cylinder (coat layer thickness: 13
μm). 24 is a urethane sponge roller. The developer application blade 25 has a linear pressure of 80 g / cm on the sleeve 22.
Is abutted. The gap between the developer carrier and the latent image holder was maintained at 250 μm, and the thickness of the toner layer was regulated at 50 μm. 6000 in each environment of 20 ℃ / 10%, 23 ℃ / 60%, 30 ℃ / 80%
The image density was 1.40 in each environment as a result of the durability test
A stable image with a fog of 1.55 was obtained.
Further, the charging roller after the durability test was hardly stained. Further, no filming occurred on the photoreceptor, and no reduction in charging efficiency was observed.

Comparative Example 1 Using the above charging step and the developer, the same printing durability test as in Example 1 was performed. After the endurance, the charging efficiency is greatly reduced compared to before the endurance. The charging roller was slightly dirty, and filming occurred on the photoreceptor. This is considered to be due to the softening agent for the rubber of the charging roller.

Comparative Example 2 Using the above charging step and the developer, the same printing durability test as in Example 1 was performed. The charging roller was dirty, and filming also occurred on the photoreceptor. Further, under low temperature and low humidity, the image density was remarkably reduced as compared with Example 1 as printing was performed.

Comparative Example 3 As a result of performing the same printing durability test as in Example 1 using the above-described charging step and the developer, contamination of the charging roller and filming on the photosensitive member occurred, and image deterioration occurred.

[Effects of the Invention] According to the present invention, the contact between the charging member and the member to be charged can be sufficiently maintained, the sticking between the charging member and the member to be charged can be prevented, and the contamination of the charging member and the member to be charged can be prevented. In addition to preventing filming, it has made it possible to obtain high-resolution, high-definition images.

[Brief description of the drawings]

FIG. 1 is an explanatory view schematically showing a charging roller according to the present invention. FIG. 2 is an explanatory view schematically showing a charging blade according to the present invention. FIG. 3 is a schematic diagram showing a triboelectric charge amount measuring device. FIG. 4 is an explanatory diagram of the developing device used in the fourth embodiment. 3. Photosensitive drum, 4.4 'Charging member 4a Metal core, 4'a Metal support member 4b Conductive rubber layer, 4'b Conductive rubber E Power supply, 11 : Suction machine 12… Measurement container, 13: Conductive screen 14… Lid, 15: Vacuum gauge 16 …… Air flow control valve, 17: Suction port 18 …… Condenser, 19: Electrometer 22 …… Sleeve, 24: Sponge roller 25 …… Blade

 ────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-877 (JP, A) JP-A-1-179951 (JP, A) JP-A-61-250656 (JP, A) JP-A-58-1983 179849 (JP, A) JP-A-62-129862 (JP, A) JP-A-63-73272 (JP, A) JP-A-58-194061 (JP, A) JP-A-63-139367 (JP, A) JP-A-1-204081 (JP, A)

Claims (4)

(57) [Claims] 1. An insulating negatively chargeable non-magnetic toner comprising at least non-magnetic colorant-containing resin particles and a fluidity improver, wherein the non-magnetic colorant-containing resin particles are composed of a diol component and a diol component. A polyester resin having a dicarboxylic acid component as a main component and at least a part of -COOH substituted by a functional group containing N, wherein at least one of the fluidity improvers is a silica fine powder; The fine powder is treated with a silane coupling agent having a positive triboelectric charging site and a negative triboelectric charging site, and further processed with silicone oil. The negatively charging non-magnetic toner has a volume average particle diameter of 6 to 6. 10 μm
The negatively chargeable non-magnetic toner is within the range of: 2. The negatively chargeable non-magnetic toner has a volume average particle diameter in the range of 6 to 10 μm and contains 15 to 40% by number of non-magnetic colorant-containing resin particles having a particle diameter of 5 μm or less. , 1
0.1 to 5.0% by volume of non-magnetic colorant-containing resin particles having a particle size of 2.7 to 16.0 μm, and 1.0% by volume or less of non-magnetic colorant-containing resin particles having a particle size of 16 μm or more; Non-magnetic colorant-containing resin particles having a particle size of ~ 10. 2. The negatively chargeable non-magnetic toner according to claim 1, wherein the following formula is satisfied. 3. The treatment amount with the silicon oil is A / 25 ± A / 30 parts by weight (A: specific surface area of the silica fine powder) based on 100 parts by weight of the silica fine powder after the silane coupling agent treatment. 3. The negatively chargeable nonmagnetic toner according to claim 1, wherein the treated silica fine powder has a hydrophobicity of 90% or more. An image having a charging step of charging the member to be charged by applying a voltage from outside to the member to be charged; a developing step of developing the member to be charged with toner; a transferring step; and a cleaning step. In the forming method, the charging member has a conductive rubber layer, and a surface layer of a release coating on at least a portion outside the conductive rubber layer and in contact with the member to be charged, The toner is an insulating negatively-chargeable non-magnetic toner having at least non-magnetic colorant-containing resin particles and a fluidity improver, wherein the non-magnetic colorant-containing resin particles have a diol component and a dicarboxylic acid component. An acid component as a main component, and-
At least a part of COOH contains a polyester resin substituted by a functional group containing N, at least one of the fluidity improvers is silica fine powder, and the silica fine powder has a positive triboelectric charging site and It is treated with a silane coupling agent having a negative frictionally chargeable portion, and further treated with silicone oil, and the negatively chargeable non-magnetic toner has a volume average particle diameter in a range of 6 to 10 μm. Image forming method.