JP2715334B2 - Image forming method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an image forming method in electrophotography. More specifically, the present invention relates to an image forming method having a charging step of charging by bringing a charging member to which a voltage is applied from the outside into contact with a member to be charged.

[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. More 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 charged member to charge the surface of the photosensitive member to a predetermined potential. If such a contact charging means is used, the voltage can be reduced as compared with a corona discharger, and the amount of generated ozone can be reduced.

For example, in Japanese Patent Publication No. 50-13661, a low voltage can be applied when photosensitive paper is charged by using a roller having a core covered with a dielectric material made of nylon or polyurethane rubber.

However, in the above conventional example, when the core metal is coated with nylon, there is no elasticity of rubber or the like, so that sufficient contact with the member to be charged cannot be maintained, and poor charging occurs.
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 softener in the rubber material of the charging member seeps out and adheres to the surface of the photoreceptor,
When the resistance of the photoreceptor is reduced and image flow occurs, the use of the photoreceptor becomes unusable at times. In other cases, toner remaining on the surface of the photoreceptor 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 affected.

In addition, when a developing process using a non-magnetic color toner is applied to an image forming method having a charging process as described above, various problems are more likely to occur.

This type of toner does not contain a magnetic substance, and often does not contain a conductive substance such as carbon black from the viewpoint of color saturation. Under low temperature and low humidity, the amount of charged electricity tends to be excessive.

Therefore, various studies have been made on the addition of conductive powder, the addition of a low-charging substance, the addition of a reverse-polarity substance, and the like in order to prevent the charging from becoming excessive. Not been.

First, when the conductive powder is added, the amount of charge under high humidity is remarkably reduced, and image density unevenness and fog are caused. Further, since the conductive powder is generally colored, it adversely affects the color of the color toner.

Further, addition of a low-charging substance (for example, JP-A-56-92545)
Japanese Patent Application Laid-Open No. 60-217368) requires a large amount of addition to obtain a sufficient fluidity-imparting effect, resulting in an excessively low charge amount or a sufficient fluidity. In many cases, the imparting effect cannot be obtained.

In addition, when the opposite polarity substance is added, if coarse particles are contained in the opposite polarity substance, the toner aggregates around the center, and a toner mass of the opposite polarity may be generated. This toner mass is
It is developed in the non-image area, and deteriorates the image quality. Therefore, a step of removing coarse particles or toner lumps is required.

In recent years, there has been a strong demand for higher image quality of copying machine images. In response to this, the present inventors have attempted to reduce the particle size of toner and faithfully reproduce latent images formed of minute dots. Have been considered to increase

However, when the particle diameter of the toner is reduced, the cohesiveness of the toner itself is increased, which causes a problem that the mixing property with the carrier is reduced or the fluidity of the toner is reduced. As the diameter increases, the specific surface area of the toner increases, so that the amount of charge in contact charging with the carrier becomes excessive, causing new problems such as low density and poor transfer.

Further, when the amount of charged electricity of the toner used becomes excessive, it is difficult to transfer the toner from the photoconductor, and the residual toner on the photoconductor increases. Therefore, toner that cannot be completely collected in the cleaning process is likely to be generated, and cleaning failure is likely to occur. Further, 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.

Thus, when trying to further reduce the particle size of the toner,
There are many problems to be faced, and among them, improvement of charging characteristics and improvement of fluidity are essential, and this point is also the most important item in toner development.

[Problems to be Solved by the Invention] The present invention has been made in view of the above points, and can sufficiently maintain contact between a charging member and a member to be charged, and prevent sticking between the charging member and the member to be charged. Further, a plasticizer contained in the conductive rubber of the charging member is adhered to the member to be charged, thereby preventing the toner from sticking to the surface of the charging member, thereby preventing charging failure and uneven charging due to filming of the toner on the member to be charged. A charging step that does not occur, a high-resolution, high-definition image can be obtained, and after the development, transfer, and cleaning steps, very little remains on the member to be charged. It is another object of the present invention to provide an image forming method comprising a toner which does not cause sticking and a developing step, a transferring step and a cleaning step using the toner.

Means and Action for Solving the Problems The present inventors have found that the non-magnetic toner for development enables high-resolution, high-definition and high-quality images, and that the charge amount does not become excessive even under low humidity. After examining what is necessary to have sufficient fluidity and maintain a certain amount of charged electricity even at high temperatures, a specific fluidity improver was added to the toner, It has been found that by specifying the particle size distribution of a toner composed of a polyester resin having a value of 5 mgKOH / g or less, a toner meeting the above object can be provided.

Specifically, the present invention provides a charging step of charging by contacting a charging member to which a voltage is applied from the outside with a photoconductor, a developing step of developing an electrostatic image with a color toner to form a toner image, An image forming method comprising: a transfer step of transferring a toner image; and a cleaning step of cleaning a color toner remaining on the photoreceptor surface after the transfer step, wherein the charging member comprises a conductive rubber and a conductive rubber layer. A color toner containing non-magnetic colorant-containing resin particles;
Having a fluidity improver, the colorant-containing resin particles have a weight average diameter of 6 to 10 μm, the binder resin of the colorant-containing resin particles has an acid value of 5 mg KOH / g or less, and A polyester resin having a total of an acid value and a hydroxyl value of 3 to 20 mgKOH / g, and the fluidity improver is a fine silica powder treated with a silane coupling agent and further treated with a silicone oil. And an image forming method.

Hereinafter, 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. First
In the figure, E indicates a DC voltage, but a voltage obtained by superimposing an AC voltage on a DC voltage may be used.

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 further provided on the peripheral surface thereof. 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 also be used. Although a blade-shaped contact charging member is used here, the conductive rubber 4'b is supported by a metal supporting member 4'a to which a voltage is also supplied, and is separated from a contact portion with the photosensitive drum 3. By providing the surface layer 4'c, which is a moldable coating, the same function 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 thereto. In order to prevent leakage to the photoconductor between the conductive rubber layer and the release coating surface layer. It is preferable to form a high-low resistance layer, for example, a hydrin rubber layer having small environmental fluctuation.

Nylon resin, PVDF (polyvinylidene fluoride), or 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 photoreceptor, if the softening agent of the conductive rubber layer adheres to the photoreceptor even a little, compared with the case where other materials are used, the image flow becomes severe, so the insulating property is applied to the outside of the conductive rubber layer. The effect of coating is great. Further, the charging device used in the present invention can be used for transfer.

Next, the toner applicable to the developing step, the transferring step, and the cleaning step in the image forming method of the present invention will be described.

According to the constitution of the present invention, in a toner having non-magnetic colorant-containing resin particles and a fluidity improver, the weight average particle diameter of the colorant-containing fine particles is 6 to 10 μm, and the binder resin of the toner is a polyester resin. Resin, the acid value of the resin is 5 mg KOH
/ g and the sum of the acid value and the hydroxyl value is 3 to 20 mgKOH / g, and the fluidity improver is treated with a silane coupling agent, and then treated with a silicon oil-treated fine silica powder. One of the features is to use a certain color toner.

In the field of research, in order to ensure that the developer has high fluidity and uniform chargeability, it has been frequently performed to add and mix a silicic acid (silica) fine powder to a toner powder.

However, since the silica fine powder is hydrophilic as it is, the developer to which it is added agglomerates due to moisture in the air to reduce the fluidity, and in extreme cases, the charging performance of the developer due to moisture absorption of silica is reduced. Lower it. Therefore, the use of hydrophobic treatment or the use of silica fine powder is disclosed in
46-5782, JP-A-48-47345, JP-A-48-4734
It is proposed in Japanese Patent Publication No. 6 and the like. Specifically, it is a method in which a silicic acid fine powder is reacted with a silane coupling agent to replace the silanol group on the surface of the silicic acid fine powder with another organic group to make the surface hydrophobic, and the silane coupling agent is, for example, dimethyldichloride. Silane, trimethylalkoxysilane and the like are used.

However, although these fine silica particles are tentatively rendered hydrophobic, the degree of hydrophobicity cannot be said to be sufficient, and when left under high humidity conditions, the charging performance of the developer is reduced.

The present inventors have studied various types of silicic acid fine powder, and as a result, have been able to avoid the above disadvantages by using silica fine powder that has been treated with a silane coupling agent and then further treated with silicon oil. I found that I can do it.

In the conventional silane coupling agent treatment, it is difficult to crush all the silanol groups of the silicic acid fine powder, and the moisture adsorption of the remaining silanol groups under high humidity is only steric hindrance by the silane coupling agent molecules after the reaction. Therefore, it is impossible to completely prevent moisture adsorption of the remaining silanol groups.

On the other hand, in the silicon oil treatment, the silicon oil is applied to the surface of the fine silica powder, so that the silanol groups can be completely covered and the moisture resistance is dramatically improved. However, in the case of only silicon oil treatment, the amount of silicon oil for covering the surface of the fine silica powder is large, aggregates of the fine silica powder are easily formed during the processing, and when applied to a developer, the fluidity of the developer is poor. Disadvantages such as In view of the above, the present inventors have conducted intensive studies,
In order to remove the agglomeration of the silicic acid fine powder while maintaining good moisture resistance, the above-mentioned disadvantages can be overcome by treating the silicic acid fine powder with a silane coupling agent and then with a small amount of silicon oil. It was found.

Silicate fine powder used in the present invention is a dry method called so-called dry method or fumed silica produced by vapor phase oxidation of a silicon halide compound, and both so-called wet silica produced from water glass and the like. can be used but less silanol groups on the inner surface and fine silica powder, and Na ₂ O, who dry silica without producing residue of SO ₃ ^2-like.

In the case of fumed silica, for example,
By using another metal halide such as aluminum chloride or titanium chloride together with a silicon halide, a composite fine powder of silica and another metal oxide can be obtained, and these are also included.

The particle size is preferably in the range of 0.001 to 2 μm as an average primary particle size, and particularly preferably 0.002 to 2 μm.
It is preferable to use silica fine powder in the range of 0.2 μm.

The silane coupling agent used in the present invention has a general formula RmSiYn R: an alkoxy group or a chlorine atom m: an integer of 1 to 3 n: an integer of 3 to 1, for example, typically dimethyldichlorosilane, trimethylchlorosilane, allyldimethylchlorosilane, hexamethyldisilazane, allylphenyldichlorosilane, benzyldimethylchlorosilane, vinyltriethoxy Examples thereof include silane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, divinylchlorosilane, and dimethylvinylchlorosilane.

The silane coupling agent treatment of the silicic acid fine powder is a dry treatment in which a silane coupling agent that has been vaporized is converted into a cloudy state by stirring the silicic acid fine powder, or
The treatment can be carried out by a generally known method such as a wet method in which fine silica powder is dispersed in a solvent and a silane coupling agent is dropped.

Silicon oil used in the present invention is generally represented by the following formula, R: C ₁ ~ ₃ alkyl group R ': alkyl, halogen-modified alkyl, phenyl, silicone oil modified group R of the modified phenyl such as ": C ₁ ~ ₃ alkyl or Arukookishi group such as dimethyl silicone oil, alkyl-modified silicone Oil, α-methylstyrene modified silicone oil,
Chlorphenyl silicone oil, fluorine-modified silicone oil and the like can be mentioned. These may be used alone or in a mixture of two or more.

As a preferred method of silicone oil treatment, after treating the silica fine powder generated by the vapor phase oxidation of the silicon halide with the silane coupling agent,
Alternatively, it is treated with a silicone oil at the same time as the treatment with a silane coupling agent. For the treatment method, a known technique is used. For example, silica fine powder and silicone oil may be directly mixed using a mixer such as a Henschel mixer, or a method of spraying silicone oil onto base silica may be used. Alternatively, it may be prepared by dissolving or dispersing a silicone oil in an appropriate solvent, mixing with a base silica fine powder, and removing the solvent.

In addition, the applied amount of these treated silica fine powders is effective when the amount is 0.01 to 20% with respect to the toner weight,
Particularly preferably, when added in an amount of 0.1 to 3%, excellent chargeability is exhibited. In a preferred embodiment of the addition mode, it is preferable that 0.01 to 3% by weight, based on the weight of the toner, of the treated silica fine powder is attached to the surface of the toner particles.

In the color toner used in the present invention, the weight average particle size of the color toner is 6 to 10 μm, and particles having a particle size of 5 μm or less are 15 to 40% by number, and 12.7 to 16.0 μm
Particles having a particle size of 0.1 to 5.0% by volume, and particles having a particle size of 16 μm or more are contained by 1.0% by volume or less;
Particles with a particle size of ~ 10. 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 a photoreceptor, and is excellent in reproducing a minute dot latent image such as a halftone dot and a digital image. An image excellent in gradation and resolution of the part is provided. 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.

Developing the latent image with the changed potential of the latent image on the photoreceptor until the latent image on the photoreceptor, and developing the toner particles on the photoreceptor (ie,
Colorant-containing resin particles) were collected, and the toner particle size distribution was measured.
It was found that about a few toner particles were present on the latent image of fine dots. That is, when toner particles having a particle size of about 5 μm are smoothly supplied to the development of the latent image on the photoreceptor, the image is faithful to the latent image, and an image with excellent reproducibility is obtained without protruding from the latent image. It is something that can be done.

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 attempted to improve the fluidity by adding the above-mentioned hydrophobized silicic acid fine powder, but with only such means, the conditions satisfying all items such as image density, toner scattering, fog, etc. It was confirmed that it was very narrow. Therefore, the present inventors further studied the particle size distribution of the toner, and found that the toner particles having a particle size of 5 μm or less
It has been found that fluidity is further improved and high image quality can be achieved by containing 0.1% to 5.0% by volume of toner particles of 12.7 to 16.0 μm after containing 40% by number. That is,
It is considered that the toner particles in the range of 12.7 to 16.0 μm have a moderately controlled fluidity with respect to the toner particles of 5 μm or less, and as a result, high-resolution images are obtained even when copying or printing is continued. This provides a sharp image with excellent characteristics and gradation.

Further, with respect to the toner particles of 0.35 to 10.1 μm, between the volume% (V), the number% (N) and the weight average particle size ( ₄ ), 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 have found that the state of existence of the particle size distribution most suitable for achieving the object as shown in 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 ₄ 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, 1.0
It is preferable that the content be as small as possible by volume.

The configuration of the present invention will be described in more detail. 5μ
The number of toner particles having a particle size of m or less is preferably 15 to 40% 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 size of 5 μm or less is 15% by number or less, 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 the content is more than 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 a latent image. The density difference between the image and 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, if it is less than 0.1% by volume,
The image density decreases 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 the transfer condition and to cause a transfer failure image. The weight-average 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.
When the weight 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 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 weight average particle diameter is 10 μm or more, the resolution is not good, and the image quality is liable to deteriorate at the beginning of copying if the use is continued at best.

As described above, by using the toner having the above-mentioned particle size distribution, good fluidity can be obtained, and a high-resolution, high-definition, high-quality copy image can be obtained. In addition, the use of the above-mentioned fluidity improver ensures stable charging even under high temperature and high humidity,
There is no scattering or fogging. This is largely due to the surface hydrophobization treatment of the silica fine powder. Further, even under low humidity, the charge amount does not become excessive, so that the transferability is good, and poor cleaning and leakage from the cleaner can be prevented.

The flowability distribution of the fluidity improver and the toner has been described above. When the binder resin made of polyester resin was examined in further detail, the carboxyl group remaining in the polyester resin greatly affected the environmental stability, and many hydroxyl groups were also present in the resin. And adversely affect the environmental stability of charging.

In other words, by lowering the acid value, the amount of carboxyl groups in the polyester resin is reduced, and the toner is less likely to absorb moisture under high humidity, whereby the decrease in charge under high humidity can be suppressed to some extent.

JP-A-62-195676, JP-A-62-195678, JP-A-62-1
No. 95680, JP-A-62-195681, JP-A-62-195682, etc., 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 present inventors have confirmed that the charge amount takes a sufficient value by containing a suitable charge control agent which is preferable in forming a toner.

However, in order to achieve further environmental stability, no matter how small the acid value is, if the hydroxyl value is excessive, the hydroxyl value will cause hydration, and the charge amount will decrease under high humidity, resulting in environmental problems. Stability is impaired.

Japanese Patent Application Laid-Open No. 62-291668 discloses that by adjusting the acid value and the hydroxyl value, particularly by controlling the acid value to 5 mgKOH / g or less, the charge of the polyester resin is neutralized and used together with a charge control agent for positive charging. A method of using as a positively charged toner has been introduced so far.

The present inventors have found that the acid value of the resin is 5 mgKOH / g or less and the sum of the acid value and the hydroxyl value is 3 to 20 mgKOH / g, preferably 4 to 15 mgKOH / g.
By adjusting the content to OH / g, a toner having sufficient environmental stability of charging and a toner having improved dispersibility of the colorant have been achieved.

In the present invention, the polyester resin may be treated with a monovalent carboxylic acid and / or a monohydric alcohol so that the acid value is 5 mgKOH / g or less and the total of the acid value and the hydroxyl value is 3 to 20 mgKOH / g.

That is, after completion of the polycondensation reaction with a divalent or higher acid and an alcohol, the acid value and the hydroxyl value are measured, and a monovalent carboxylic acid and / or a monohydric alcohol in an approximately equimolar amount are added to the reaction system for treatment. Thereby, the acid value and the hydroxyl value are adjusted. The toner using this polyester resin is excellent in fixing property and anti-offset property, excellent in environmental stability, good in fluidity and blocking resistance, and can be hardly deteriorated.

As the polyhydric alcohol component of the polyester resin used in the present invention, ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol,
2,3-butanediol, diethylene glycol, dipropylene glycol, triethylene glycol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, pentaerythritol diallyl ether, trimethylene glycol, 2-ethyl-1, 3-hexanediol, hydrogenated bisphenol A, and a bisphenol derivative represented by the following formula; (Wherein 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 10
It is. ) And the like.

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

The alcohol component used in the present invention is 40-60mo
l%, preferably 45-55 mol%, as acid component 60-40mo
It is desirably 1%, preferably 55 to 45 mol%.

The monovalent carboxylic acid used in the present invention is represented by the general formula R-COOH. Here, R is an aliphatic group such as an alkyl group or an alkenyl group, an aromatic group, or a heterocyclic group, and specifically, is a compound as shown below.

Formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, pivalic acid, lauric acid, myristic acid, palmitic acid, stearic acid, acrylic acid, propiolic acid, methacrylic acid, crotonic acid, oleic acid, benzoic acid, toluic acid , Naphthoic acid, cinnamic acid, 2-furic acid, nicotinic acid,
There is isonicotinic acid and the like, among which acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, pivalic acid, lauric acid, propiolic acid, methacrylic acid, stearic acid,
Benzoic acid, toluic acid, naphthoic acid and 2-furic acid, more preferably acetic acid, propionic acid, valeric acid and benzoic acid.

The monohydric alcohol used in the present invention is represented by the general formula R-OH. Here, R is an aliphatic group such as an alkyl group or an alkenyl group, an aromatic group, or a heterocyclic system, and specifically, the following compounds are used.

Methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol,
Isobutyl alcohol, sec-butyl alcohol, tert
-Butyl alcohol, n-amyl alcohol, isoamyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, caprylic alcohol, allyl alcohol, crotyl alcohol, propargyl alcohol, cyclopentanol, cyclohexanol, benzyl alcohol, cinnamyl alcohol, furfuryl Alcohols, particularly preferably methyl alcohol, ethyl alcohol, isobutyl alcohol, sec-butyl alcohol, tert-butyl alcohol, n-amyl alcohol, isoamyl alcohol, allyl alcohol, crotyl alcohol, cyclopentanol, and benzyl alcohol, more preferably Means methyl alcohol, ethyl alcohol, isobutyl alcohol, allyl alcohol, benzyl alcohol It is.

When the molecular weight of the monohydric carboxylic acid or monohydric alcohol used in the present invention is large, a soft segment is formed at the end group of the polyester resin, which causes inconveniences such as offset resistance and spent of the carrier. Here, R preferably has 1 to 10 carbon atoms.

The amount of monohydric carboxylic acid or monohydric alcohol added was determined by the following formulas (I) and (II). The addition amount is set to be approximately equimolar to the acid value or the hydroxyl value.

The method for producing the polyester resin is as follows.

Under an inert gas atmosphere (often in the presence of nitrogen gas)
The reaction is carried out at normal pressure to reduced pressure (0~-760mmH ₂ O). With stirring, the temperature is raised to 60 to 270 ° C, preferably to 80 to 220 ° C,
Incubate for 30 hours. Water or alcohols produced by the condensation polymerization are continuously discharged out 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 reaction vessel equipped with a stirrer, a condenser, a thermometer, and an inert gas introduction pipe. Next, gas replacement is performed by introducing an inert gas. After the completion of the gas replacement, 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 produced by the condensation polymerization reaction is condensed and recovered by a condenser outside the system. At the end of the reaction, the acid value and the hydroxyl value were measured, and the above formulas (I) and (II) were used.
The carboxylic acid and alcohol represented by are added. Here, when a carboxylic acid and an alcohol are used as the monomer, the carboxyl group and the hydroxyl group are treated with the alcohol and / or the carboxylic acid.

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

Next, the method of measuring the acid value and the hydroxyl value used in the present invention will be described below.

Measurement of Acid Value 2 to 10 g of a sample are weighed in a 200 to 300 ml Erlenmeyer flask, and about 50 ml of a mixed solvent of methanol: toluene = 30: 70 is added 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, titrate with a pre-standardized N / 10 potassium hydroxide-alcohol solution, and calculate the following formula (II
Find the acid value in I).

Acid value = KOH (ml) × N × 56.1 / Sample weight (III) (where N is a factor of N / 10 KOH) Measurement of hydroxyl value A sample is heated with an excess of an acetylating agent such as acetic anhydride to obtain acetyl. After the saponification value of the resulting acetylated product is measured, it is calculated according to the following formula (IV).

(However, A represents the saponification value after acetylation, and B represents the saponification value before acetylation.) The toner according to the present invention may contain a charge control agent in order to stabilize 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.
Examples of the negative charge control agent at that time include an organic metal complex such as a metal complex of an alkyl-substituted salicylic acid (for example, a chromium complex or a zinc complex of di-tert-butylsalicylic acid). When the negative charge control agent is blended in the toner, 0.1 to 10 parts by weight, preferably 0.5 to 100 parts by weight of the binder resin.
It is better to add up to 8 parts by weight.

When preparing a two-component developer by mixing with the toner according to the present invention, the mixing ratio is as a toner concentration in the developer,
Good results are usually obtained with 2 to 10% by weight, preferably 3 to 9% by weight. When the toner concentration is less than 2% by weight, the image density is low and cannot be used practically. When the toner concentration is more than 10% by weight, fog and scattering in the machine are increased, and the useful life of the developer is shortened.

As the colorant used in the present invention, known dyes and pigments,
For example, phthalocyanine blue, induslen blue, peacock blue, permanent red, lake red,
Rhodamine lake, Hansa yellow, permanent yellow, benzine yellow and the like can be widely used.
The content thereof is 12 parts by weight or less, preferably 0.5 to 9 parts by weight with respect to 100 parts by weight of the binder resin so as to be sensitively reflected on the permeability of the OHP film.

Additives may be added to the non-magnetic color toner of the present invention as needed as long as the properties of the toner are not impaired. Examples of such additives include Teflon, zinc stearate, and polyvinylidene fluoride. And a fixing aid such as low molecular weight polyethylene and low molecular weight polypropylene.

In the production of the non-magnetic color toner of the present invention, a hot roll, kneader, kneading the constituent materials well by a hot kneader such as an extruder, then mechanical pulverization, a method of obtaining by classification, or in a binder resin solution A method in which a material such as a magnetic powder is dispersed in and then obtained by spray drying, or a method in which a predetermined material is mixed with a monomer to constitute a binder resin, and then the emulsified suspension is polymerized. Each method such as a method for producing a polymerized toner for obtaining the above formula can be applied.

About the carrier used by mixing with the toner of the present invention,
An electrically insulating resin is used as a coating resin for the carrier core material, and is appropriately selected depending on a toner material and a 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 polyester resin particles having a high negative chargeability are 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 To 5
It is preferably 70% by weight.

The average molecular weight of the copolymer, the number average molecular weight is 10,000 in consideration of the uniformity of the coating of the carrier core material surface, the coating strength.
~ 35,000, preferably 17,000-24,000, weight average molecular weight is 2
It is preferably between 5,000 and 100,000, preferably between 49,000 and 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, metals such as iron, nickel, copper, zinc, cobalt, manganese, chromium, rare earth and the like, and their alloys or oxides, whose surface is oxidized or not oxidized, can be used. Also, there is no particular restriction on the manufacturing method.

Hereinafter, each of the measuring methods (1) and (2) relating to the characteristic value of the toner used in the present invention will be described.

(1) Particle size distribution measurement: A Coulter Counter TA-II type (manufactured by Coulter) was used as a measuring device, and an interface (manufactured by Nikkaki) for outputting the number distribution and volume distribution and a CX-1 personal computer (manufactured by Canon) were used. Connect and use 1% sodium chloride as the electrolyte to prepare a 1% NaCl aqueous solution. As a measuring method, 0.1 to 5 ml of a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersing agent to 100 to 150 ml of the electrolytic aqueous solution, and 2 to 20 ml of a measurement sample is further added. The electrolyte in which the sample was suspended was subjected to dispersion treatment for about 1 to 3 minutes using an ultrasonic disperser, and the volume and number of the toner were measured using the Coulter Counter TA-II, using a 100 μm aperture as the aperture. The volume distribution and number distribution of 〜40 μm particles were calculated. Then, the weight basis and weight average diameter determined from the volume distribution according to the present invention
D4 (the median value of each channel is the representative value for each channel), and the amount of weight-based coarse powder (16.0μ
m or more), the number of fine powders based on the number obtained from the number average (5.
04 μm or less).

(2) Measurement of triboelectric charge: FIG. 3 is an explanatory view of a triboelectric charge measuring device. First, a mixture of particles to be measured and magnetic particles used as a developer is prepared. The mixing ratio is 5 parts by weight for 95 parts by weight of magnetic particles in the case of toner and colorant-containing fine particles, and 2 parts by weight in 98 parts by weight of magnetic particles in the case of a fluidity imparting agent. .

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

Next, a mixture of particles and magnetic particles whose triboelectric charge amount is to be measured is placed in a metal measuring container 12 having a conductive screen 13 of 500 mesh (which can be appropriately changed to a size that does not allow magnetic particles to pass) at the bottom. Cover the metal lid 14. At this time, the weight of the entire measurement container 12 is weighed and defined as 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 sufficiently performed (about 2 minutes) to remove toner by suction. The potential of the electrometer 19 at this time is set to V (volt). Where 18
Is a capacitor and the capacity is C (μF). Also,
The weight of the whole measuring container after suction is weighed and is defined as W ₂ (g). This triboelectric charge amount T (μc / g) is calculated as follows.

EXAMPLES Hereinafter, the present invention will be described in detail with reference to Examples (Examples of producing a polyester resin and Examples of a toner using the resin). Parts mean parts by weight.

Resin production example 1 The above compounds were mixed at a molar ratio of 1: 1 and placed in a 2 l four-necked round bottom flask equipped with a thermometer, a Teflon coating, a stirring blade, a glass nitrogen inlet tube, a condenser, and a pressure reducing device. After the by introduction of nitrogen gas reactor than the glass inlet tube an 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 a condensation reaction was performed at 170 ° C. for 20 hours. The pressure at this time was also kept at -750mmH ₂ O.

At this time, the acid value was 8.2 mgKOH / g, and the hydroxyl value was 19.0 mgKOH / g.
g. This is designated as resin A.

After this, 120 ml of acetic acid and 40 ml of ethanol were added to the system,
The reaction product water and residual acetic acid were excluded from the system to obtain resin B. At this time, the acid value was 3.4 mgKOH / g and the hydroxyl value was 2.3 mgKOH / g.

Separately, instead of 120 ml of acetic acid, 150 acrylic acid
Resin C was obtained by adding 50 ml of propanol instead of 40 ml of ethanol and 40 ml of ethanol. The acid value at this time is 3.9mgKOH / g, hydroxyl value
2.7 mgKOH / g.

Resin Production Example 2 An acid value of 6.3 mg KOH / g and a hydroxyl group were obtained in the same manner as in Production Example 1 except that bisphenol A ethoxy adduct was used instead of bisphenol A propoxy adduct and dodecenyl succinic anhydride was used instead of maleic anhydride. Resin D having a value of 2.3 mg KOH / g was obtained.

Thereafter, 40 ml of ethanol was added thereto, and a resin E having an acid value of 3.2 mgKOH / g and a hydroxyl value of 2.4 mgKOH / g was obtained in the same manner as in Production Example 1.

Example 1 Is sufficiently premixed with a Henschel mixer, melt-kneaded at least twice with a three-roll mill, cooled, roughly crushed to about 1 to 2 mm using a hammer mill, and then finely crushed by a fine crusher using an air jet method. did. Further, the obtained finely pulverized product was classified to select a particle size of 2 to 10 μm so as to have the particle size distribution of the present invention, thereby obtaining colorant-containing resin particles.

The colorant-containing resin particles are Met.

Next, Aerosil # 200 silicate fine powder with a specific surface area of 200 m ² / g
After 100 parts (manufactured by Nippon Aerosil Co., Ltd.) are treated with 20 parts of hexamethyldisilazane (HMDS), dimethylsilicone oil KF-96 100cs (manufactured by Shin-Etsu Chemical) is diluted with a solvent and treated with 10 parts. After drying, heat treatment at about 250 ° C,
After the hexamethyldisilazane treatment, fine silicic acid powder treated with dimethylsilicone oil was obtained, and 0.4 part was externally added to 100 parts of the above-mentioned classified product to obtain a cyan toner.

Styrene 50%, methyl methacrylate 20%, 2-ethylhexyl acrylate 30
% (Number average molecular weight 21,250, weight average molecular weight 52,360) having a weight average particle diameter of 45 μm, 4.2% of 35 μm or less,
A Cu-Zn-Fe-based ferrite carrier having a particle size distribution of 35 to 40 µm, 9.5%, and a particle size distribution of 34 µm or more and 0.2% was mixed with a 0.5% -coated carrier so that the total amount became 100 parts to prepare a developer.

Using this developer, a charging device of a plain paper color copying machine (Canon CLC500) having a commercially available OPC photoreceptor was modified so as to have the configuration shown in FIG. In FIG. 1, the outer diameter of the charging roller 4 is 12 mmφ, the conductive rubber layer 4b is made of EPDM, and the surface layer 4c is made of a 10 μm thick nylon resin. The hardness of the charging roller 4 is 54.5 ° (ASKER-
C).

 The applied voltage was adjusted so that the development contrast was 270V at 23 ° C / 65%, 330V at 20 ° C / 10%, and 250V at 30 ° C / 80%.

As a result, in each environment, the image density was stable at 1.45 to 1.55 and clear without any fog. further,
No cleaning failure occurred, and no decrease in charging efficiency was observed.

Comparative Example 1 An image was formed in the same manner as in Example 1 except that the resin A was used instead of the resin B. As a result, the toner was scattered sharply under high temperature and high humidity, and the durability was interrupted halfway.

This is presumably because the acid value and the hydroxyl value of the resin used were large and water was easily adsorbed to the toner, and the charge amount of the developer was reduced.

Comparative Example 2 An image was formed in the same manner as in Example 1 except that the surface layer 4c was not provided in the charging device of Example 1, and toner fusion occurred on the photosensitive member. This is considered to be due to the softening agent of the rubber of the charging roller.

Comparative Example 3 An image was formed in the same manner as in Example 1 except that fine silica powder that had not been treated with dimethylsilicone oil after being surface-treated with hexamethyldisilazane was used. The image below had a lot of fog, and when the durability was further continued, the scattering of the toner in the machine became noticeable.

Example 2 The same procedure as in Example 1 was carried out except that the surface layer 4c was made of PvdF resin in the charging device of Example 1, and good results were obtained.

Example 3 An image was formed in the same manner as in Example 1 except that resin C was used instead of resin B in Example 1.
Good results were obtained.

Example 4 An image was produced in the same manner as in Example 1 except that the charging device was modified so as to have the configuration shown in FIG. 2 instead of the charging device used in Example 1, and good results were obtained. Further, even in the durability of 20,000 sheets, the decrease in the charging efficiency was small, and no filming on the photoreceptor occurred.

Example 5 Was used to obtain magenta resin particles.

After 100 parts of the resin particles were treated with γ-aminopropyltriethoxysilane, 0.5 part of fine silica powder which was surface-treated with methyl hydrogen silicone oil (trade name: TSF484, manufactured by Toshiba Silicone Co., Ltd.) was externally added to obtain a magenta toner.

Otherwise, when the image was formed in the same manner as in Example 1, good results were obtained under high temperature and high humidity and under low temperature and low humidity.

Comparative Example 4 In Example 5, the acid value was 6.3 mgKOH / g instead of resin E.
When the image was formed in the same manner except that the resin D was used, the image under high temperature and high humidity showed a lot of fog, and the fluidity of the agent was a little lower than that in Example 5. Was.

Comparative Example 5 The same image was obtained under the same conditions as in Example 5 except that fine silica powder not surface-treated with γ-aminopropyltriethoxysilane and not treated with silicone oil was used. Toner scattering was conspicuous, and it was difficult to control the image density during running to a constant level.

Comparative Example 6 The same flow as in Example 5 was carried out except that fine silica powder which was directly surface-treated with silicone oil without surface treatment with γ-aminopropyltriethoxysilane was used. And the toner supply from the hopper to the developing device did not proceed smoothly. In addition, the obtained image was rough, and the ground fog was severe.

[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 showing an outline of a charging roller of the present invention, FIG. 2 is an explanatory view showing an outline of a blade according to another embodiment of the present invention, and FIG. FIG. 3 ... Photoconductor drum 4 '... Charging member E ... Power supply

Claims (2)

(57) [Claims] A charging step of contacting a charging member to which a voltage is applied from the outside with a photosensitive member to perform charging; a developing step of developing an electrostatic image with a color toner to form a toner image; and transferring the toner image. And a cleaning step of cleaning the color toner remaining on the surface of the photoreceptor after the transfer step. The charging member includes a conductive rubber layer and an outer side of the conductive rubber layer. The color toner has non-magnetic colorant-containing resin particles and a fluidity improver, and has a release coating at least at a portion that contacts the photoreceptor. The colorant-containing resin particles have an acid value of 5 mgKOH / g or less, and the total of the acid value and the hydroxyl value is 3 to 20 mgKOH / g. Is a polyester resin, Image forming method, wherein the flow improver after being treated with a silane coupling agent, a further fine silica powder treated with silicone oil. 2. The colorant-containing resin particles contain 15 to 40% by number of particles having a particle size of 5 μm or less, and have a particle size of 12.7 to 16.0 μm.
Containing 0.1 to 5.0% by volume of particles having a particle size of 16.0 μm
Containing not more than 1.0% by volume of particles having the above particle size;
Particles with a particle size of ~ 10. 2. The image forming method according to claim 1, wherein the following condition is satisfied.