JP2782208B2 - Multicolor electrophotographic toner - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multicolor electrophotographic toner, and more particularly to a color toner capable of obtaining a clear and wide color tone by mixing two or more colors of toner.

[Related Art] In recent years, the development of monocolor copying to full-color copying in copying machines and the like is rapidly progressing, and studies and practical use of two-color copying machines and full-color copying machines are being actively conducted.

For example, in color image formation by full-color electrophotography, reproduction of all colors is generally performed using three color toners of three primary colors, yellow, magenta, and cyan.

In this method of forming a color image, first, an electrostatic latent image is formed on a photoconductive layer by passing light from a document through a color separation light transmission filter having a complementary color to the color of the toner, and then through a development and transfer process. The toner is held on a support. Next, the above-described steps are sequentially performed a plurality of times. After the toner is overlaid on the same support while the registration is being performed, a final full-color image is obtained by one-time fixing.

As described above, a toner used in a multicolor electrophotography method which requires development and transfer a plurality of times and superposition of several types of toner layers having different colors on the same support has the following characteristics. Is needed.

(1) To have a preferable transporting property and mixing property so that toner can be smoothly supplied from the toner hopper to the developing device and can be easily mixed with the carrier and the developer.

(2) Good storage stability so that there is no caking or cohesion during handling or storage.

(3) In a plurality of transfer steps, the first toner layer does not hinder the transferability of the second toner layer.

Further, when such a toner is used as a developer, the following characteristics are further required.

(4) Forming a uniform and sufficient amount of a developer layer on a developer carrier such as a sleeve in a development area.

(5) It has good charging characteristics with little environmental dependency.

On the other hand, as a developing method used for such a toner, there are a cascade developing method described in U.S. Pat. No. 2,618,552, a magnetic brush method described in U.S. Pat. No. 2,874,063, and a touch-down method.

Of these, the most commonly used method is the magnetic brush method. This method uses magnetic particles such as steel and ferrite as a carrier. The developer including the toner and the magnetic carrier is held by a magnet, and the magnetic field of the magnet arranges the developer in a brush shape. When the magnetic brush contacts the electrostatic latent image surface on the photoconductive layer, only the toner is attracted from the brush to the electrostatic latent image and development is performed.

However, in this magnetic brush method, since the ratio of consumable toner in the magnetic brush in the developing area is small, the developability is extremely low. Also, if a large amount of developer is used in order to enhance the developability, the size and weight of the developing device are increased, which is not suitable for reducing the size and weight of the copying machine. In particular, since a multicolor color copying machine requires at least two developing units, in such a case, it is impossible to reduce the size of the multicolor color copying machine.

On the other hand, in order to increase the developing efficiency, a developing method such as a developing method of applying a bias electric field in which an AC component and a DC component are superposed between the developer carrying member and the electrostatic latent image carrying member to perform the developing is used. A method has been proposed, but simply increasing the development efficiency allows, for example, even coarse particles generated during the toner manufacturing process to be developed on the latent image carrying member, and as a result, the latent particles are formed by the coarse particles. The gap between the image bearing member and the transfer member becomes uneven, and the periphery of the coarse particles becomes poor in transfer, resulting in image defects. The image defect has a high image area ratio,
This is likely to occur when the amount of toner consumption is large, and becomes a serious problem particularly in a color copy image such as a photograph. Further, when multiple transfer is performed, the image defects are more coordinated.

In order to eliminate such coarse particles in the toner that cause image defects, coarse particles are generally removed by an air classifier or the like. Cannot be smoothly supplied to the hopper, blockage in the hopper, variation in the supply amount, and the like. Further, when a developer is used, the fluidity of the developer is reduced, which not only causes a non-uniform coat of the developer, but also
A plurality of transfers cause a decrease in charging characteristics.

[Problems to be Solved by the Invention] An object of the present invention is to provide a multicolor toner having good transferability.

Another object of the present invention is to provide a multicolor toner having sufficient triboelectric charging characteristics.

Still another object of the present invention is to provide a multicolor toner capable of forming a coat layer having a uniform and sufficient developer amount in a developing area.

Still another object of the present invention is to provide a multicolor toner having good transportability.

Still another object of the present invention is to provide a multicolor toner with less scattering.

Still another object of the present invention is to provide a multicolor toner which is hard to be spent on a carrier even when repeatedly used and has excellent durability.

[Means and Actions for Solving the Problems] The inventors of the present invention have made intensive studies, and as a result, have been trying to realize suitable characteristics especially as a toner for multiple transfer while maintaining good transportability, developability and transferability. Has found that it is rather necessary that a coarse toner, especially a toner having a particle size larger than the normal toner particles, be present in a certain quantitative range.

That is, the present invention has an apparent viscosity of at least 1 × 10 ^{4 to} 5 × 10 ⁵ poise and 5 × 10 ^{4 to} 5 × 1 at 100 ° C. and 90 ° C.
After mixing the colorant-containing polyester resin particles and the flow improver at ⁶ poise uniformly using a mixer with high-speed rotating blades set so that the maximum peripheral speed is 20 to 80 m / sec, A polyester color toner obtained by a method for producing a multicolor electrophotographic toner having a step of removing coarse particles present after mixing through a 100-150 mesh sieve and then sieving at least once with a 200-400 mesh sieve, The colorant-containing polyester resin particles have a volume average particle size of 3 to 10 μm, and the flow improver includes Al ₂ O ₃ , TiO _2
2 , Sc ₂ O ₃ , ZrO ₂ , GeO ₂ and at least a metal oxide selected from the group consisting of HfO ₂ , the obtained polyester color toner has a coarse particle content of 100 mesh on A multi-color electron, wherein the content of coarse particles of 200 mesh-on is 3 particles / 100 g or less of toner and the content of particles of 16 μm or more is 0.1 to 2.5% in the volume diameter distribution. It is a photographic toner.

The present invention will be described in further detail with reference to the drawings as necessary. In the following description, “%” and “parts” representing quantitative ratios are based on weight unless otherwise specified.

DETAILED DESCRIPTION OF THE INVENTION Referring to FIG. 1, which is a schematic side sectional view in the thickness direction of a transfer material, showing an example of a full-color electrophotographic copying machine to which the multicolor electrophotographic toner according to the present invention can be applied. The operation of the machine will be described.

Referring to FIG. 1, an electrostatic latent image formed on a photosensitive drum 1 by an appropriate means is used to develop a first color image in a developing unit 2a attached to a rotary developing unit 2 rotating in the direction of arrow A. Visualized by an agent (not shown). This developed toner image is transferred by a transfer charger 5 to a transfer material (not shown) held on a transfer drum 4 by a gripper 3.

Next, as the second color, the rotary developing unit 2 rotates in the direction of arrow A, and the developing device 2b faces the photosensitive drum 1. The electrostatic latent image on the drum 1 corresponding to the second color is
The developed toner image is developed by the developer of the second color in 2b, and this developed toner image is also transferred onto the same transfer material as above.

Further, the development of the third and fourth electrostatic latent images and the transfer of the developed toner image are performed in the same manner as in the second color. In this way, the transfer drum 4 rotates a predetermined number of times while holding the transfer material, and a toner image of a predetermined number of colors is multiplex-transferred onto the transfer material. The transfer material subjected to the multiple transfer is separated from the transfer drum 4 by a separation charger 6 and passes through a fixing device 7 to become a final full-color copy image.

On the other hand, the replenishment toner supplied to the developing units 2a to 2d of the respective colors is supplied in a fixed amount based on the replenishment signals from the replenishment hoppers 8a to 8d provided for the respective colors via the toner transport cable 9,
The toner is conveyed to the toner supply cylinder 10 at the center of the rotary developing unit 2 and further sent to each of the developing devices 2a to 2d.

Referring to FIG. 2, which is an enlarged schematic cross-sectional view of the toner replenishment system-development system portion of FIG.
The developer is uniformly mixed with the developer in the developing device 2a in advance by the mixing-conveying screw 11 so as to have a predetermined developer concentration.

The mixing ratio of the carrier and the toner at this time is a very important factor from the viewpoint of the developing effect.

That is, the developer attached to the surface of the sleeve 12 containing the magnet (not shown) rubs the electrostatic latent image on the photosensitive drum 1 to visualize the latent image with toner. As a result, the toner is gradually consumed from the developer, and the ratio of the toner to the carrier decreases, that is, the concentration of the developer decreases,
The density of the developed image gradually decreases. Therefore, the toner is appropriately replenished to the developing units 2a to 2d. In this case, if the toner is replenished more than an appropriate amount, the density of the image becomes excessively high and fogging increases. Therefore, in order to continuously obtain images having a preferable color tone, it is necessary to maintain an appropriate toner density in the developing units 2a to 2d.

To maintain such an appropriate toner concentration, the toner is required to have sufficient transportability and sufficient mixability with a carrier, but in order to achieve this purpose, the content of coarse particles of 100 mesh on is required. The amount is substantially zero, the content of coarse particles of 200 mesh-on is 3 / 100g toner or less, and the content of particles of 16 μm or more in the volume diameter distribution is
It needs to be 0.1 to 2.5%. In particular, in order to maintain sufficient transportability as a toner and sufficient mixability with a carrier, the ratio of toner coarse powder of 16 μm or more is extremely important.

When the content of toner particles having a particle size of 16 μm or more is more than 2.5%, the transportability is good, but the mixing property with the carrier is not sufficient, the toner is scattered, and the chargeability is reduced particularly under high humidity. , Fog increases.

On the other hand, when the toner particles having a particle size of 16 μm or more are less than 0.1%, toner scattering is reduced, but not only the flowability as a developer is deteriorated, but also the developability is deteriorated, and the toner is easily blocked in the hopper. Inconsistency.

 Hereinafter, the development will be described in more detail.

FIG. 2 shows an example of a replenishment-development system using the full-color toner of the present invention. When the replenishment toner and the developer already in the developing unit are uniformly mixed via the transport-mixing screw 11, the replenishment-development system is 16 μm or more. 0.1% of toner particles
If less, the mixture of the replenished toner and the developer,
In other words, the replenishment of the replenished toner into the particle aggregate in which the toner is already electrostatically adhered to the carrier surface becomes poor, and as a result, a constant and uniform developer concentration can be obtained in a short time. The toner density cannot be attained, and the toner concentration partially changes in the developer.

If there is such a non-uniformity in the toner concentration, the developing ability of the developer on the developing sleeve 12 will vary, and the non-uniform development will be performed for the same latent image potential on the photosensitive drum 1. Problems such as partial fog and density unevenness occur in terms of image quality.

On the other hand, when the toner particles having a particle size of 16 μm or more are more than 2.5%, scattering of the toner from the developing sleeve 12 in the machine during development is promoted, which causes contamination of the wire of the charged corotron. Further, such a toner has too much fluidity, so that the toner passes through the toner transport cable 9 in a jet state and overflows in the toner supply cylinder 10.

Means for achieving the toner coarse powder amount specified in the present invention include binder resin particles having a preferable particle size distribution, and the type and amount of a flow improver described later, and the preferable particle size of the color toner of the present invention. It is obtained by selecting and controlling the distribution, and furthermore, the amount of the contained colorant that migrates to the surface of the resin particles and is exposed, in other words, the compatibility of the colorant in the binder resin, the type of the colorant, and the like. be able to.

Next, an example of a developing method using the toner of the present invention will be described.

That is, referring to FIG. 2, a bias electrolysis composed of a DC component is applied between the developing sleeve 12 and the photosensitive drum 1 having an electrostatic latent image, and the developing unit 12
The upper toner and the toner adhering to the carrier surface may be transferred and developed to the photosensitive drum 1.

Further, the charge amount of the toner on the developing sleeve in such a developing method is measured by directly absorbing the developer from the sleeve, separating the toner and the carrier, and guiding the toner to a Faraday gauge. The charge amount of the toner in the developer on the sleeve in the development using the developer of the present invention is usually -10 to -60 µc / g, preferably -15 to -50 µc / g. The above charge amount is -10 in absolute value
If it is less than μc / g, toner scattering from the developing sleeve during development becomes remarkable, and in a high-temperature and high-humidity environment (32.5 ° C., 85% RH), the toner is scattered in the copying machine, making it practically impossible.

When the charge amount exceeds -60 μc / g in absolute value, the toner adheres firmly and electrostatically to the carrier surface in a low-temperature and low-humidity environment (15 ° C., 10% RH), and has an electrostatic latent image. Transfer of the toner onto the photosensitive drum becomes substantially impossible.

The present invention is more effective when a polyester resin is used as the binder resin for a toner of the present invention.

In the present invention, in particular, (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
~ 10. A) a diol component comprising a bisphenol derivative or a substituted product thereof, and a carboxylic acid component comprising a divalent or higher carboxylic acid or an acid anhydride thereof or a lower alkyl ester thereof (for example, fumaric acid, maleic acid, maleic anhydride, A polyester resin obtained by at least co-condensation polymerization with phthalic acid, terephthalic acid, trimellitic acid, and pyromellitic acid) is more preferably used because it has sharp melting characteristics.

If necessary, the carrier used in combination with the toner of the present invention includes, for example, metals such as iron, nickel, copper, zinc, cobalt, manganese, chromium, rare earth and the like, and their alloys or oxides, which are not oxidized or surface oxidized. And ferrite. There is no particular restriction on the manufacturing method.

Further, the surface of the carrier can be coated with a resin or the like. As the method, any conventionally known method such as a method of dissolving or suspending a coating material such as a resin in a solvent, coating and adhering to a carrier, and a method of simply mixing with a powder can be applied.

The fixing substance on the carrier surface varies depending on the toner material, for example, polytetrafluoroethylene, monochlorotrifluoroethylene polymer, polyvinylidene fluoride, silicone resin, polyester resin, metal complex of ditersharry butylsalicylic acid, styrene resin,
Acrylic resin, polyacid, polyvinyl butyral,
It is suitable to use nigrosine, amino acrylate resin, basic dyes and lakes thereof, fine silica powder, fine alumina powder or the like alone or in combination of two or more, but it is not necessarily limited thereto.

The treatment amount of the above-mentioned fixing substance may be appropriately determined so that the charge amount of the carrier satisfies the above-mentioned condition. In general, the total amount of the coating material is 0.1 to 10% by weight (preferably 0.2 to 5%) with respect to the carrier (after coating). % By weight) is preferred.

The average particle size of these carriers is preferably 20 to 80 μm, preferably 25 to 70 μm, more preferably 30 to 65 μm.

The carrier preferably has a sharp particle size distribution. In this case, favorable triboelectricity is obtained with respect to the toner of the present invention, and there is an effect of further improving electrophotographic characteristics.

When a toner and a carrier according to the present invention are mixed to prepare a two-component developer, the mixing ratio is 2.0% by weight to 12% by weight, preferably 3% by weight to 9% by weight, as the toner concentration in the developer. In general, good results are obtained. If the toner density is less than 2.0%, the image density is low, making it impractical. If the toner density is more than 12%, fog and scattering in the machine increase, and the useful life of the developer is shortened.

The flow improver used in the present invention is a flow improver having an absolute value of a charge amount of 30 μc / g or less when frictionally charged with iron powder, and more preferably a flow improver of 10 μc / g or less. It is necessary to contain one or more agents. Further, the absolute value of the charge amount is in the above range, and the chargeability is opposite to that of the toner, but the effect of the present invention is greater.
Further, in order to impart fluidity, it is effective that the particle size of the flow improver is small, and in the present invention, a specific surface area is measured by the BET method, and a flow improver of 30 m ² / g or more is used. . More preferably, it is 50 m ² / g or more.

Conversely, if the flow improver is too fine, it is not suitable for the present invention. That is, since the charge amount increases by the amount corresponding to the increase in the specific surface area, the property of low chargeability is lost. Also,
If the particle size is small, it will be easy to be embedded in the toner matrix,
It is difficult to find appropriate addition conditions. In the present invention, those having a specific surface area of 300 m ² / g or less as measured by the BET method are used.

Examples of the flow improver having the above triboelectric charging properties include the following. For example, Al ₂ O ₃ , TiO ₂ , GeO
_2, ZrO _2, Sc ₂ and O _3, HfO ₂ or the like of metal oxides, SiC, TiC, W carbides and the like _{2 C, Si 3 N 4,} Ge 3 N nitrides such ₄ preferably chargeability is low It is. Among them, Al ₂ O ₃ , TiO ₂ , Sc ₂ O ₃ , ZrO ₂ , GeO ₂ , H
Since fO ₂ is colorless or white and is suitable for use in a color toner without adversely affecting the color, the flow improver used in the present invention contains at least a metal oxide selected from these. In particular, Al ₂ O ₃ and TiO ₂ are more preferable because they can be easily produced with a suitable particle size by a gas phase method. In addition, even if the silica fine powder has a strong negative charging ability,
It can be used in the present invention by weakening the charging ability by surface treatment or the like.

In the present invention, as a further flow improver, any one can be used as long as it can be added to the colorant-containing resin particles to increase the flowability before and after the addition.

Specific examples of such a flow improver include fluorine resin powders, that is, fine powder of vinylidene fluoride, fine powder of polytetrafluoroethylene, and the like; or metal salts of resin acids, that is, zinc stearate, calcium stearate, and stearic acid. Lead or the like; or a metal oxide, such as zinc oxide powder; or fine-powder silica, that is, a wet-processed silica, a dry-processed silica, or a treatment obtained by subjecting such silica to a surface treatment with a silane coupling agent, a titanium coupling agent, silicone oil, or the like. Silica and the like.

In the present invention, at least a colorant-containing resin particle having a volume average particle diameter of 3 to 10 μm is formed by using a mixer in which a high-speed rotating blade is set so that the maximum peripheral speed is 20 to 80 m / sec. After uniformly mixing the improver, coarse particles present after mixing are passed through a 100-150 mesh sieve, and then adopted a process of removing it by sieving at least once with a 200-400 mesh sieve, Generally, stainless steel is used as the material of the sieve, and the flow improver is excessively charged with a mesh having a high charging ability, and causes clogging and the like. This tendency is remarkable at a mesh size of 200 mesh or less where the mesh size is small.

Therefore, for the purpose of preventing clogging, for example,
DALTON vibrating sieves have the function of tapping the sieve mesh lightly with a tapping ball or the like from below, but according to this method, clogging of the sieve is certainly reduced, but as in the present invention, the melt viscosity is small. If you use toner,
Conversely, by being hit with a tapping ball or the like, the toner is likely to be granulated or a toner mass is easily formed, which makes application to the present invention difficult.

However, in the present invention, since the flow improver contains at least 30 μc / g or less of the flow improver having a charge with the iron powder, the charge between the toner particles and the mesh is also suppressed, and the passage of the toner through the mesh is reduced. Good.

The amount of the flow improver added to the colorant-containing resin particles is 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the resin particles. If the amount is less than 0.01 part by weight, there is no effect on improving the fluidity. If the amount is more than 10 parts by weight, fogging or bleeding of letters and scattering of toner inside the machine are promoted.

Coloring agents suitable for the purpose of the present invention include the following pigments or dyes. In the present invention, CI Disperse Y164, CI Solvent Y77 and CI
Colorants such as Solvent Y93 are unrecognizable.

As the dye, for example, CI Direct Red 1, CI
Direct Red 4, CI Acid Red 1, CI Basic Red 1, CI Modern Red 30, CI Direct Blue 1, CI Direct Blue 2, CI Acid Blue 9, CI Acid Blue 15, CI Basic Blue 3, CI Basic Blue 5, CI Modern Blue 7, etc.

As the pigment, naphthol yellow S, Hansa yellow G, permanent yellow NCG, permanent orange GTR, pyrazolone orange, benzidine orange G,
Permanent Red 4R, Watching Red Calcium Salt, Brilliant Carmine 3B, Fast Violet B, Methyl Violet Lake, Phthalocyanine Blue, Fast Sky Blue, Indanthrene Blue BC
Etc.

Preferred pigments include disazo yellow pigments, insoluble azo pigments, and copper phthalocyanine pigments. Preferred dyes include basic dyes and oil-soluble dyes.

Particularly preferably, CI Pigment Yellow 17, CI Pigment Yellow 15, CI Pigment Yellow 13, CI Pigment Yellow 14, CI Pigment Yellow 12, CI
Pigment Red 5, CI Pigment Red 3, CI Pigment Red 2, CI Pigment Red 6, CI Pigment Red 7, CI Pigment Blue 15, CI Pigment Blue 16, or a phthalocyanine skeleton having the structural formula (1) shown below: A copper phthalocyanine pigment which is a Ba salt in which two or three carboxybenzamide methyl groups are substituted;

Particularly preferred dyes used are CI Solvent Red 49, CI Solventlet 52, CI Solvent Red 109, CI Basic Red 12, CI Basic Red.
1, CI Basic Red 3b.

The content of these colorants is preferably 15 parts by weight or less, more preferably 0.1 to 9 parts by weight, based on 100 parts by weight of the binder resin.

It is also preferable that the toner according to the present invention contains a charge control agent in order to stabilize the negative charge characteristics. At that time, a colorless or light-colored negatively charge-controlling agent which does not affect the color tone of the toner is particularly preferable. Examples of the negative charge control agent include an organometallic 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 added to the toner, it is added in an amount of 0.1 to 10 parts by weight, preferably 0.5 to 8 parts by weight, based on 100 parts by weight of the binder resin.

Since the toner of the present invention is used for multiple transfer, it is necessary to sufficiently remove coarse particles that cause transfer failure. For this reason, conventionally, in a toner, for example, a 100-mesh sieve is used after being mixed with a flow improver or the like, but the flow improver itself is often an aggregate itself, and after passing through the sieve. Reagglomeration easily occurs. Therefore, when mixing the colorant-containing resin particles and the flow improver, it is necessary to sufficiently disperse them on the toner surface.

In the present invention, any mixer can be used without particular limitation as long as it can uniformly disperse the colorant-containing resin particles and the flow improver. In the present invention, for example, a V-type mixer, a Nauta mixer, an instant mixer with high-speed rotating blades, and the like are preferably used. Above all, as a final means of mixing, a mixer having a high-speed rotating blade, particularly an instantaneous mixer utilizing shearing force of such a blade and mixing while shearing cohesive fine powder such as a flow improver is particularly preferable. Used.

In the present invention, the fixability of the toner is a very important factor from the viewpoint of color mixing of multiple toners. In such a multi-toner, the toner is multi-layered on the transfer support, color mixing is performed by one fixing, and various colors are developed according to the toner coverage on the transfer material. If the fixing property is poor enough that the toner particles can be discerned under a microscope, the fixing toner particles may be irregularly reflected with respect to light, resulting in an image having a reduced chroma and a smudge, and consequently a reduction in color reproducibility. become.

Further, when the image is transferred to an OHP film, if the fixing property is poor, the light transmittance is poor, and although the desired color tone is almost reproduced by the reflected light, the transmitted light may become dark gray.

On the other hand, considering only the fixing property of the toner, the high temperature offset, the winding of the transfer material around the fixing roller, and the increase in the complexity and cost of the fixing device due to the provision of a device for applying a large amount of oil to prevent this, increase the cost. Invite. In addition, oil marks on the copied image will cause deterioration of image quality.

From such a viewpoint, in the toner of the present invention, 90
The apparent viscosity at 5 ° C. is preferably 5 × 10 ^{4 to} 5 × 10 ⁶ poise, more preferably 7.5 × 10 ⁴ to 2 × 10 ⁶ poise, and particularly preferably 1 × 10 ⁵ to 1 × 10 ⁶ poise. Is preferably 1 × 10 ^{4 to} 5 × 10 ⁵ poise, more preferably 1 × 10 ^{4 to} 3.0 × 10 ⁵ poise, and particularly preferably 1 × 10 ⁴ to 2 × 10 ⁵ poise. Due to such a melt viscosity of the toner, the fixing property, the color mixing property, and the high-temperature offset resistance of the full-color toner are more favorably achieved.

In the present invention, in particular, the apparent viscosity P at 90 ° C.
The absolute value of the difference between ₁ and the apparent viscosity P _{2 at} 100 ° C. is 2
It is preferably in the range of poise of × 10 ⁵ <| P ₂ −P ₁ | <4 × 10 ⁶ .

On the other hand, the endothermic peak temperature in the DSC (differential thermal analysis) measurement of the toner is also correlated with the fixability, and an excessively high endothermic peak temperature deteriorates the fixability, and an excessively low endothermic peak temperature causes a problem of storage stability, especially for ships. During transportation, if the temperature rises in the hold, blocking may occur in the toner bottle.

For the fixability of the color toner, the above 90 ° C, 10
Particularly good results are achieved when both the apparent viscosity of 0 ° C. and the endothermic peak temperature of the DSC are satisfied.

In the toner of the present invention, it is desirable that the temperature of the endothermic peak of DSD is in the range of 58 to 72 ° C, preferably 61 to 70 ° C, and more preferably 62 to 70 ° C according to the present invention.

In order to achieve the apparent viscosity at 90 ° C. and 100 ° C. of the present invention, and the endothermic peak value of DSC, the selection or production of the monomer composition of the binder resin, the monomer type, the crosslinking agent, and the initiator while considering the image quality. Conditions must be carefully set. For example, general printed matter and photographs have a considerable gloss on the surface, which serves to enhance image quality.

In the present invention, since a very sharp melt performance is required as a toner, the colorant-containing resin particles themselves are very easily melted by heat. Therefore, sufficient care must be taken when mixing the colorant-containing resin particles with the flow improver.

As the mixing conditions, it is necessary that the maximum peripheral speed (tip speed of the blades) of the rotating blades of the mixer is 20 to 80 m / s, preferably 25 to 60 m / s. When the peripheral speed is less than 20 m / s, the cohesive fine powder (flow improver) is insufficiently sheared, and is easily released from the toner as coarse particles.
On the other hand, if the peripheral speed is higher than 80 m / s, the colorant-containing resin particles and the like are likely to be granulated and fused, and coarse particles are undesirably generated.

In the present invention, after mixing the colorant-containing resin particles with the flow improver, it is necessary to remove coarse particles through a sieve. The opening of the above sieve is 100-1 as the first stage
50 mesh, 200 to 400 mesh for the second and subsequent stages. One stage is insufficient, and it is desirable to pass two to five times, preferably two times. If the number of times of sieving is more than 5, coarse particles can be removed very satisfactorily, but the colorant-containing resin and the flow improver tend to separate due to sieving, which is not preferable.

The mixer for the toner and the carrier in the present invention is not particularly limited as long as it can uniformly mix and disperse the toner and the carrier. For example, a rotary cylindrical type, a double cone type, a V-type mixer, or the like can be given.

The mixing condition of the toner and the carrier may be such that the toner and the carrier can be uniformly mixed. However, it is conceivable that the toner and the carrier may be mixed due to granulation and fusion of the toner during mixing. It is desirable to sift through a 40-100 mesh sieve, more preferably a 60 mesh sieve.

By employing the above steps in the production of the toner and the developer, it is possible to completely remove coarse particles that cause transfer failure, and it is possible to eliminate image defects particularly in multiple transfer.

Hereinafter, the measurement method of various characteristics used in this specification (1)
(5) will be described.

(1) 100 mesh on coarse grain, 100 mesh pass 200
Measurement of Mesh-on Coarse Particles A powder tester (manufactured by Hosokawa Micron) is used as a measuring device.

The measuring method is as follows. That is, 200-mesh and 100-mesh screens are set on the vibrating table of the above apparatus in an order of narrow opening, that is, so that 100-mesh is at the top. The input voltage to the shaking table is adjusted to 30 V, and the amplitude of the shaking table at that time is adjusted so as to fall within the range of 60 to 90 μm, and 100 g of toner is dropped on 100 mesh in about 5 minutes. One minute later, stop the vibration.

Next, the residue on 100 mesh and 200 mesh is observed with a loupe, and the remaining amount of each is evaluated. In the present invention, the content of coarse particles of 100 mesh-on is zero, which excludes substances that are electrostatically attached to the mesh, that is, substances having a particle size smaller than the mesh opening and electrostatic aggregates. This is an evaluated value. Even at 200 mesh on, evaluation is made excluding those considered to be apparent electrostatic adhesion.

(2) Measurement of apparent viscosity A flow tester CFT-500 type (manufactured by Shimadzu Corporation) is used. The sample weighs about 1.0 to 1.5 g of a 60mesh pass product. This is performed by using a molded product and applying a pressure of 100 kg / cm ² for 1 minute.

This pressurized sample is subjected to a flow tester measurement under the following conditions under normal temperature and normal humidity (temperature: about 20 to 30 ° C., humidity: 30 to 70% RH) to obtain a humidity-apparent viscosity curve. From the obtained smooth curve, an apparent clay at 90 ° C. and 100 ° C. is determined, and this is defined as an apparent viscosity with respect to the temperature of the sample.

RATE TEMP 6.0D / M (℃ / 1 minute) SET TEMP 70.0DEG (℃) MAX TEMP 200.0DEG INTERVAL 3.0DEG PREHEAT 300.0SEC (second) LOAD 20.0KGF (kg) DIE (DIA) 1.0MM (mm) DIE (LENG 1.0MM PLUNGER 1.0CM ² (cm ² ) (3) Measurement of triboelectric charge The measurement method will be described in detail with reference to the drawings.

FIG. 3 is a schematic perspective view for explaining an apparatus for measuring a triboelectric charge amount of toner. Referring to FIG. 3, first,
In a metal measuring container 22 having a 500-mesh screen 23 at the bottom, a mixture of the toner and the carrier whose weight ratio is to be measured in a ratio of 1: 9 is put. This mixture is 50-100
A polyethylene bottle having a capacity of ml is placed and shaken manually for about 10 to 40 seconds. At this time, the weight of the entire measurement container 22 is weighed and set as W ₁ (g). Next, the suction device 21 (the part in contact with the measurement container 22 is at least an insulator)
In the above, the pressure of the vacuum gauge 25 is set to 250 mmAq by adjusting the air volume control valve 26 by suctioning from the suction port 27. In this state, suction is sufficiently performed, preferably for 2 minutes, to remove the toner by suction. The potential of the electrometer 29 at this time is set to V (volt). Where 28
Is a capacitor, and the procedure is C (μF). Also,
The weight of the whole measuring container after suction is weighed and is defined as W ₂ (g). The triboelectric charge (μc / g) of this toner is calculated as in the following equation.

(However, the measurement conditions are 23 ° C. and 60% RH.) The carrier used for the measurement is a fluororesin-switch-type resin-coated ferrite carrier containing 70 to 90% by weight of carrier particles of 250 mesh pass and 350 mesh on. use. That is, a 5: 5 mixture of vinylidene fluoride-tetrafluoroethylene copolymer and styrene-2-ethylhexyl acrylate-methyl methacrylate is 0.2%.
Use a ferrite carrier coated with ~ 0.7% by weight.

Sample toner and carrier used for measurement are 23 ℃, 60% RH
After leaving it for at least 12 hours in the environment, use it for charge measurement.

 The measurement of the triboelectric charge is performed in an environment of 23 ° C. and 60% RH.

(4) Endothermic peak value measurement by DSC DSC is an abbreviation of differential thermal analysis.

In the present invention, the measurement is carried out using a differential thermal analysis measuring device (DSC measuring device), DSC-7 (manufactured by PerkinElmer).

The measurement sample is precisely weighed in an amount of 5 to 20 mg, preferably 10 mg.

Put this in an aluminum pan and use an empty aluminum pan as a reference.
The measurement is performed at normal temperature and normal humidity at a heating rate of 10 ° C./min.

The temperature at which the endothermic peak of the main peak in the temperature range of 40 to 100 ° C. is obtained as the endothermic peak value of the present invention in this heating process.

(5) Particle size distribution measurement Coulter counter TA-II type (manufactured by Coulter) is used as a 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 electrolyte in which the sample was suspended was subjected to a dispersion treatment for about 1 to 3 minutes with an ultrasonic disperser, and the Coulter Counter TA-II was used to perform 2 to 4 using a 100 μ aperture as an aperture.
The volume average distribution and the number average distribution are determined by measuring the particle size distribution of the 0μ particles.

From the obtained volume average distribution, values of 16.0 μ or more of the volume average particle diameter and the volume average distribution are obtained.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples.
“%” And “parts” indicate “% by weight” and “parts by weight”.

Example 1 Colorant-containing resin particles of four colors using 100 parts of a polyester resin obtained by condensing propoxylated bisphenol and fumaric acid, respectively, using a colorant and a charge control agent in the prescribed amounts shown in Table 1 below. I got

The above-prepared amounts of the polyester resin, the colorant and the charge control agent are each preliminarily mixed with a hensial mixer, melt-kneaded at least twice with a three-roll mill, and cooled to about 1 to 2 mm using a hammer mill. It was coarsely pulverized and then finely pulverized by an air jet type pulverizer. Further, the finely pulverized products obtained above were classified to obtain classified products (4 types) having volume average particle diameters of 7.9 μm, 8.3 μm, 8.0 μm, and 9.4 μm, respectively. Each 100 parts of this classified product, as a flow improver, a BET specific surface area of ^{_{105m 2 / g Al 2 O 3}} 0.3 parts of weight with 15% treated with hexamethyldisilazane having a BET specific surface area of 230 m ² / g of silica 0.5 part of each fine powder was externally added at a peripheral speed of 40 m / sec using a Henschel mixer. Then remove the tapping ball from Dalton Vibration
Through 100 mesh sieve and 200 mesh sieve,
Four types of yellow, magenta, cyan and black color toners were obtained.

When the coarse particles of this toner were examined, the particles of 100 mesh-on were 0 for all of the magenta, cyan, yellow, and black toners, and the particles of 200 mesh-on were 1, 2, 1, 3, respectively. Was. In addition, coarse particles of 16 μm or more were 0.5%, 0.3%, 0.9% and 1.4%, respectively.

For this color toner, a Cu-
A Zn-Fe-based resin-coated carrier was mixed to a total amount of 100 parts to prepare a developer. In consideration of color tone reproducibility, toner scattering, and the like, the developer concentrations of the yellow, magenta, cyan, and black color toners are 5%, 5%, and 6%, respectively.
%, 6%. After the developer was sieved with a sieve of 60 mesh, coarse particles were checked. As a result, the coarse particles of 60 mesh on were 0 for all four toners.

Using the four types of developers obtained above, a color electrophotographic apparatus having an OPC (organic photoconductor) photosensitive drum as shown in FIGS. 1 and 2 and a replenishment-development system (manufactured by Canon Inc.)
A copy test was performed using CLC-1).

An example of the supply-development system used in the present invention will be described.
The replenished toner sent by 13 is connected to the developing device 2b at the toner replenishing port 14 in FIG. 2 and is supplied into the developing device 2b.

When the developing device 2b rotates and comes to a position facing the photosensitive drum 1, the replenishment toner is uniformly mixed with the developer within a very short time by the mixing-conveying screw 11, and the developer having a constant developer concentration is obtained. Becomes

The developer is provided on a developing sleeve 12 with a developer regulating blade.
As a result, the amount of the developer becomes a fixed amount, and the negatively charged toner is transferred onto the photosensitive drum 1 by the magnetic brush developing method at the opposite portion of the photosensitive drum 1 having the negatively charged electrostatic latent image. In this embodiment, the distance between the sleeve and the photosensitive drum in the developing area was set to 800 μm.

Using this method, a full-color image that faithfully reproduces the original color chart without fog was obtained even after 50,000 printings (continuous copying) in the full-color mode.
Further, the transfer in the copying machine and the detection of the developer density were good, and a stable image density was obtained. Furthermore, even when an OHP film was used as the transfer material, the transparency of the toner was very favorable. At the time of 1000 sheets and 5000 sheets,
When 500 half-tone images (A3) having an original density of 0.5 were continuously copied, no image defects due to poor transfer considered to be caused by coarse grains were found.

The triboelectric charges of the yellow, magenta, cyan, and black toners of the present invention were −30.5 μc / g and −29.6 μc, respectively.
/ g, −31.2 μc / g, and −25.6 μc / g.

Further, Table 2 shows the apparent viscosity and endothermic peak value of the examples.

Comparative Example 1 Four kinds of toners were prepared in the same manner as in Example 1 except that the toner after adding the flow improver was passed once through a 100-mesh sieve instead of passing through a 100-mesh sieve and a 200-mesh sieve twice. The toner and developer were prepared and evaluated, and the color reproducibility and durability were good. However, in a halftone image test performed in the same manner as in Example 1 at 1000 sheets and 5000 sheets, , 5/500 each
Image defects due to poor transfer, which are considered to be caused by coarse grains of 20 sheets / 500 sheets, were observed. 20 out of 100 g of toner at this time
The coarse grains of 0 mesh on are 5, 4, 3, respectively in the order of magenta, cyan, yellow, and black,
There were five.

Comparative Example 2 Example 1 was repeated except that the toner after adding the flow improver was passed twice through a 100-mesh sieve instead of passing through the 100-mesh sieve and the 200-mesh sieve twice in Example 1.
When four types of developers were prepared and evaluated in the same manner as described above,
Image defects due to poor transfer were observed. At this time, the coarse particles of 200 mesh-on of the toner were three, three, two, and three in the order of magenta, cyan, yellow, and black, respectively.
And 3/100 g toner.

Comparative Example 3 The same operation as in Example 1 was carried out except that Al ₂ O ₃ was not used as the magenta toner in Example 1. As a result, although 100 mesh passed over time, 200 mesh was very clogged and the productivity was severe. Decreased significantly.

 At this time, the triboelectric charge was −63 μc / g.

Therefore, in Comparative Example 3, when the tapping ball was used for the Dalton vibration sieve, the passing property of 200 mesh was improved, but the number of coarse grains of 200 mesh on was 8/10.
The weight was 0 g, and the image was formed as in Example 1. As a result, image defects were confirmed.

Comparative Example 4 A toner was produced in the same manner as in Example 1, except that a fine powder of Al ₂ O _{3 and a} fine silica powder were externally added to the magenta colorant-containing resin particles at a peripheral speed of 15 m / sec using a Henschel mixer. As a result, a large amount of silica aggregate remained on the 100 mesh and the mesh. When the Al ₂ O ₃ content and the silica content of this toner were determined by fluorescent X-ray,
The amount was 0.28 part of Al ₂ O ₃ and 0.40 part of silica with respect to 100 parts of the toner.

When an image was formed using this toner in the same manner as in Example 1, the toner transportability was deteriorated particularly under low temperature and low humidity (15 ° C./10%), and the toner was blocked in the toner hopper and the toner was removed. The mixture with the carrier was insufficient, and image density unevenness occurred.

Comparative Example 5 A toner was manufactured in the same manner as in Example 1 except that silica fine powder was externally added to magenta colorant-containing resin particles at a peripheral speed of 100 m / sec using a Henschel mixer. In addition to the severe fusion of the toner to the toner, a large amount of coarse particles were generated, and the continuous operation of the toner manufacturing apparatus was not possible.

Example 2 In Example 1, magenta toner was replaced with B instead of Al ₂ O _3.
Extraction was carried out in the same manner as in Example 1 except that 0.4 parts of TiO ₂ fine powder having an ET specific surface area of 80 m ² / g was used, and good results were obtained as in Example 1.

At this time, the triboelectric charge of the magenta toner was −27.6 μc /
g.

Example 3 In Example 1, after passing through a 100-mesh and a 200-mesh sieve, the Dalton vibrating sieve was remodeled, an electromagnetic vibrator was attached above the mesh, and 400 mesh was applied while applying vibration to the mesh itself. The same operation as in Example 1 was performed except that the toner was allowed to pass, and the toner passed the mesh very well without clogging of the toner. When an image was formed using this toner in the same manner as in Example 1, good results were obtained. At this time, the coarse particles of 200 mesh on were 0 for all four colors.

[Effects of the Invention] In the present invention, since the polyester-based color toner particles having a particle size larger than ordinary toner particles are present in a specific quantitative range, transferability is good, and triboelectrification characteristics and transportability are improved. Etc. are sufficient and have excellent image characteristics.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view schematically showing a color electrophotographic copying machine to which the color toner of the present invention is applied, and FIG.
FIG. 3 is an enlarged view of a replenishment system-development system portion of the copying machine shown in FIG. 3, and FIG. 3 is a schematic perspective view schematically showing an apparatus for measuring a triboelectric charge amount of toner. DESCRIPTION OF SYMBOLS 1 ... Photosensitive drum, 2a-2d ... Developing device 4 ... Transfer drum, 7 ... Fixing device 8a-8d ... Toner supply hopper 9 ... Toner conveyance cable, 10 ... Toner supply cylinder 11 ... Mixing- Transfer screw, 12 ... Sleeve

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-63-128363 (JP, A) JP-A-59-33459 (JP, A) JP-A-63-208862 (JP, A) JP-A 62-128 174772 (JP, A) JP-A-62-260159 (JP, A) JP-A-59-40651 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 9/08

Claims (1)

(57) [Claims] 1. A colorant-containing polyester resin particle having an apparent viscosity of at least 1 × 10 ^{4 to} 5 × 10 ⁵ poise and 5 × 10 ^{4 to} 5 × 10 ⁶ poise at 100 ° C. and 90 ° C., and a flow improver. After uniformly mixing using a mixer with high-speed rotating blades set so that the maximum peripheral speed is 20 to 80 m / sec,
A polyester color toner obtained by a method for producing a multicolor electrophotographic toner having a step of removing coarse particles present after mixing by passing through a 100-150 mesh sieve and then sieving at least once with a 200-400 mesh sieve, The colorant-containing polyester-based resin particles have a volume average particle size of 3 to 10 μm, and the flow improver includes Al ₂ O ₃ , TiO _2
2 , Sc ₂ O ₃ , ZrO ₂ , GeO ₂ and at least a metal oxide selected from the group consisting of HfO ₂ , the obtained polyester color toner has a content of coarse particles of 100 mesh on A multi-color electron, wherein the content of coarse particles of 200 mesh-on is 3/100 g or less of toner and the content of particles of 16 μm or more in the volume diameter distribution is 0.1 to 2.5%. Photo toner.