JPH02287551A - Toner for developing electrostatic charge image - Google Patents

Abstract

PURPOSE:To suppress the peeling and wear of the shell layer or intermediate layer of the positively chargeable toner by using polyester for core particle and using respectively different styrene/acryl copolymers for the intermediate layer and the shell layer. CONSTITUTION:This positively chargeable toner is formed by using the polyester for the core particles, the styrene/acryl copolymers (e.g: styrene/butyl acrylate copolymers) for the intermediate layer and the shell coating layer and further using the copolymer lower in styrene content than the copolymer used in the intermediate layer for the shell layer. The defective electrostatic charge and the ground fogging of images by the peeling or wear of the shell layer or the intermediate layer are solved according to this constitution, by which the durability and stability of the toner are enhanced and the quality of the images is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a toner for developing electrostatic latent images. More particularly, the present invention relates to toners for developing electrostatic images that provide high definition images in electrophotography, electrostatic recording, and electrostatic printing.

Conventional technology The development of an electrostatic latent image in electrophotography, electrostatic recording, and electrostatic printing is made visible by electrostatically attracting triboelectrically charged toner to the electrostatic latent image formed on a photoreceptor. It is done by doing.

As a method for charging the toner used in developing such an electrostatic latent image, in a two-component development method, it is known that charging is imparted by mixing and stirring with a substance generally called a carrier. Furthermore, in the -component development method, it is known that charge is imparted by contact with a developing sleeve, a toner regulating blade, a photoreceptor, or the like. Regardless of the method, if the toner is not uniformly charged, problems occur during development and transfer.

Furthermore, in recent years, toners for developing electrostatic latent images have become more precise, have higher image quality, or have more diverse toner functions.
To accommodate various uses, various types of toners having a laminated structure have been proposed for the purpose of functional separation or improvement of surface properties.

A toner with a laminated structure is a toner that is made up of laminated layers that are individually given each of the properties required for a toner, such as fixing properties, coloring properties, charging properties, etc., in order to best develop them. be. Polyester resins are strong and unbreakable, and transparent ones also exist. Therefore, when a toner is formed using a polyester resin as a core particle, a toner having excellent color tone, fixing properties, transparency, etc. can be obtained.

However, in a toner in which core particles are simply stacked, the outermost surface coating layer or the inner intermediate layer is likely to peel off or wear out due to mixing and agitation in a developing device during use or friction with the carrier.

In other words, once the surface of the toner is destroyed or worn out, parts of the laminated toner have exposed intermediate layers with different charging properties, resulting in poor charging of the toner and the formed image having a lot of background fog. . In particular, polyester resins are generally negatively chargeable, and this has a large effect on positively chargeable toners whose core material is polyester resin.

Further, when the colorant is exposed on the surface of the toner particles due to peeling of the outermost surface layer, the charging property changes greatly depending on the type of colorant and the amount of exposure. As a result, the distribution of the amount of charge on the toner becomes wide, causing problems such as toner scattering and fogging.

Further, the peeled and worn particles interact with other toners or carriers by rubbing against each other, adversely affecting developer charging and image quality.

Moreover, the fine particles produced by layer peeling are small in size;
It adheres strongly to the photoreceptor and is difficult to remove with a cleaner, resulting in poor cleaning and filming. Furthermore, when the amount of fine powder (particularly fine powder of 5 μm or less) increases, the fluidity of the developer decreases significantly, resulting in poor mixing and agitation, unevenness of the developer in the developing machine, and a decrease in development efficiency.

As the laminated structure toner, for example, Japanese Patent Application Laid-Open No. 61-2757
No. 67, a layer consisting of a magnetic material and/or a coloring agent is provided on the surface of the core particle, and further contains at least one type of 7-mer selected from fluorine-containing monomers, amino group-containing monomers, and nitro group-containing monomers. The toner is made by laminating capsule layers made of seven polymers in a wet process.
Further, Japanese Patent Publication No. 59-38583 discloses a toner in which a coating layer made of microparticles formed by emulsion polymerization is wet-formed on the surface of core particles.
No. 6162 discloses a toner in which fine resin particles are wet-adhered to the surface of a colored thermoplastic resin and then heat-treated. In all of these toners, we focused on the fact that the electrical properties of the toner mainly depend on its surface area, and by attaching resin fine particles to the surface of core particles containing colorants, magnetic substances, etc. This is an attempt to achieve stable charging properties through physical properties or surface shape. However, in these toners, the resin layer wet-adhered to the surface of the core particles adheres to the core particles while retaining its particle shape, as is clear from the electron micrograph shown in JP-A No. 62-226162. Therefore, the resin layer does not completely cover the surface of the core particle (that is, it is not dense). Therefore, even in toners with such a configuration, there is a high risk that stable charging properties may not be obtained due to the influence of colorants, magnetic powder, etc. in the core particles, and especially if the toner is stored under severe temperature conditions or When used, the components constituting the core particles leak out onto the toner surface through the gaps between the minute resin particles, causing an even greater effect. Incidentally, when the core particle component leaches onto the surface of the toner in this manner, a problem arises in that the toner particles also coagulate together.

Problems to be Solved by the Invention The present invention solves the problem of removing the outermost surface that is exposed when the surface coating layer or the intermediate layer inside it peels off or wears out due to mixing and agitation in the developing device or friction with the carrier during use. It solves problems caused by the intermediate layer (or core particles) below the layer, such as the occurrence of poorly charged toner and the occurrence of image background fog, and forms high-quality images with excellent durability and stability, and little background fog. The purpose is to provide a toner with a laminated structure that can be used.

Means for Solving the Problems The present invention provides a toner for developing electrostatic images having a laminated structure comprising a core particle, an intermediate coating layer and an outer shell coating layer laminated in this order on the core particle, wherein the core particle is made of a polyester resin. The intermediate coating layer and the outer shell coating layer are composed of a styrene-acrylic copolymer resin, and the styrene monomer content of the styrene-acrylic copolymer resin is higher in the outer shell coating layer than in the intermediate coating layer. This invention relates to a positively chargeable toner having a low chargeability.

The toner for developing electrostatic images of the present invention is composed of three layers: a core particle, an intermediate coating layer, and an outer shell coating layer.

The core particles mainly play a role in fixing the toner, and the polyester resin may be selected or prepared from this point of view. Transparent polyester resins can also be prepared.
Transparent color toner can also be obtained according to the following description, and even in that case, it is possible to form a color (full color) image i without impairing the effects of the present invention.

The polyester resin used in the present invention is synthesized from, for example, a polyol component and dicarboxylic acid. Examples of the polyol component include ethylene glycol, triethylene glycol, 1,2-propylene glycol, 1.3-7'
Robylene glycol, 1,4-butanediol, 1,4
-Bis(hydroxymethyl)cyclohexane, bisphenol A1, hydrogenated hisphenol A1, polyoxyethylated bisphenol A, etc. can be used, and dicarboxylic acid components include maleic acid, fumaric acid, mesaconic acid, citraconic acid, itaconic acid, and glutaconic acid. Acid, phthalic acid, isophthalic acid, terephthalic acid, succinic acid, adipic acid, sepacic acid, Mac'7 acid, 1,2.4-benzenetricarboxylic 11゜2.5-benzenetricarvone L 1.2.4-> Clohexanetricarboxylic acid, 1
, 2.5-cyclohexanetricarboxylic acid, 1.2.4
-butanetricarboxylic acid, 1,3-dicarboxy-2-
Methyl 2-methylcarboxypropanetetra(methylcarboxy)methane and the like can be used.

The polyester resin obtained as described above is generally used after being crushed into fine particles, but since the shape and particle size distribution of the core particles greatly affect the shape and particle size distribution of the final toner particles, it is preferable to have a spherical shape. It is preferable that the particle size is high and the particle size distribution is narrow. Further, the core particles may contain a coloring agent.

Therefore, the core particles have an average particle diameter of 1 to 20 μm, preferably 3 to 15 μm, more preferably 5 to 10 μm.
of resin particles is used.

In the toner for developing electrostatic latent images of the present invention, core particles made of the above polyester resin are coated.

Since this coating layer is further coated as described below, the coating layer of the core particle is referred to as an "intermediate coating layer" in this specification.

The intermediate coating layer is made of styrene or styrene-acrylic copolymer resin.

The intermediate coating layer is formed of a styrene-acrylic copolymer resin, and the styrene-acrylic copolymer resin used for forming the layer has a styrene monomer unit ratio (hereinafter referred to as "Sl") of 10 to 100%, preferably 20%. -100%, more preferably 50-100%. The proportion (Sl) of the styrene thread on the styrene yarn is made of a styrene-acrylic resin having a value of at least 10% as Sl, taking into consideration the formation of the outer shell coating layer to be described later.

By making the intermediate coating layer have the above-mentioned structure, it becomes possible to form the intermediate coating layer uniformly, and the adhesion between the intermediate coating layer and the core particles becomes strong, making it difficult for the core layer to peel off, and finally The resulting toner can be made more suitable for positively charging properties. When a colorant is contained in the core particles, the intermediate coating layer completely covers the colorant exposed on the surface of the core particles, thereby preventing the colorant from having an adverse effect on the charging characteristics of the toner.

The thickness of the intermediate coating layer is approximately determined by the size of the resin particles used when forming the intermediate coating layer, which will be described later.
The thickness may be about 115 or less of the average particle diameter of the core particles,
It does not matter how thin it is as long as it can prevent the adverse effects of exposing the surface of the core particle.

The method for forming the intermediate coating layer is to mechanically mix core particles and microparticles (i.e., resin particles) with a small particle size, more specifically about 115 or less (i.e., resin particles) with respect to the core particles, at an appropriate blending ratio. After the fine particles are uniformly attached to the periphery of the core material formed by van der Waalska and electrostatic force, the fine particles are blown away by a localized temperature rise caused by, for example, an impact force. Preferred examples include a method of forming a film by softening it. Polyester resins are generally negatively chargeable, and the smaller the styrene monomer unit content of the styrene-acrylic copolymer resin particles used to form the intermediate coating layer, the more positively chargeable they become, so they adhere uniformly to the surface of the core particles. do.

According to such a method, the shape and particle size distribution of the core particles are not substantially changed, and even if the resin of the intermediate coating layer has a higher softening point than the thermoplastic resin of the core particles, it is easy to It is possible to form a layer that substantially completely covers the outer surface of the core particle.

Apparatuses that can be suitably used in the method for forming the intermediate coating layer include the No\Ibridization System (manufactured by Nara Kikai Seisakusho Co., Ltd.) that applies a high-speed air impact method, Ongmill (manufactured by Honkawa Micron Co., Ltd.), and Mechanomill (manufactured by Kaida Seiko Co., Ltd.). (manufactured by).

However, the method for forming the synthetic resin coating layer is not limited to the above methods.

Examples of the styrene monomer constituting the styrene-acrylic copolymer resin include styrene, 0-methylstyrene, m-methylstyrene, p-methylstyrene, p-
Ethylstyrene, 2,4-dimethylstyrene, p n-
Butylstyrene, 1) Lert butylstyrene, p n
-hexylstyrene, pn-octylstyrene, pn
-nonylstyrene, pn-decylstyrene, pn-
Examples include styrene and derivatives thereof such as dodecylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, and 3,4-dichlorostyrene, among which styrene is most preferred.

Acrylic monomers constituting the styrene-acrylic copolymer resin include acrylic acid, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-octyl acrylate, and dodecyl acrylate. , 2-ethylhexyl acrylate, stearinoacrylic acid, acrylic acid and its derivatives such as 2-chloroethyl acrylate, phenyl acrylate, methyl α-chloroacrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, propyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, etc. Examples include methacrylic acid and derivatives thereof, (meth)acrylic acid derivatives such as acrylonitrile, methacrylonitrile, acrylamide, and the like.

Further, in the toner for developing electrostatic latent images of the present invention, the resin particles used for forming the intermediate coating layer may be obtained by a pulverization method, a granulation polymerization method such as emulsion polymerization or suspension polymerization, a suspension method, or a spray drying method. Any toner particles may be used as long as they can be obtained by a known method for manufacturing toner particles, such as by a wet granulation method such as a method such as a wet granulation method.
The particles preferably have a narrow particle size distribution, and those obtained by a granulation polymerization method such as emulsion polymerization or suspension polymerization are preferable. In particular, among these granulation polymerization methods, when granulation is performed using a method known as seed polymerization, particles with high sphericity and narrow particle size distribution can be easily obtained, and the degree of polymerization can also be easily controlled. Therefore, it becomes an extremely desirable resin particle. This seed polymerization is
As shown in Japanese Patent Application No. 69, a part of the polymerizable upper layer and a polymerization initiator are added to an aqueous medium or an aqueous medium containing an emulsifier, and emulsified by stirring. It is gradually added dropwise to obtain minute particles, and using these particles as seeds, polymerization is carried out in the polymerizable droplets.

Furthermore, any polymerization initiator, particularly an oil-soluble polymerization initiator, can be used in the usual temperature range as the polymerization initiator used when polymerizing the above polymerizable monomers to obtain desired resin particles. As a specific example of the polymerization initiator, 2.2″
-azobisisobutyronitrile, 2.2'-azobis-
Azo compounds such as 2,4-dimethylvaleronitrile, 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, acetylcyclohexylsulfonyl peroxide, diisopropyl peroxydicarbonate, decanonyl peroxide, lauroyl peroxide oxide, stearoyl peroxide, acetyl peroxide, L-butyl peroxy-2-ethylhexanoate, benzoyl peroxide, t-butyl peroxyisobutyrate, cyclohexanone peroxide, methyl ethyl ketone peroxide, dicumyl peroxide, t Examples include peroxides such as -butyl hydroperoxide, di-t-butyl peroxide, and cumene hydroperoxide. The amount of these polymerization initiators to be used is 0.degree.-10 parts by weight, more preferably 0.5 to 5 parts by weight, per 100 parts by weight of seven polymers. If the amount used is less than 0.01 part by weight, the polymerization rate will be slow;
On the other hand, if the amount is more than 10 parts by weight, it becomes difficult to control the polymerization.

It is also possible to incorporate a coloring agent into the resin particles thus obtained. Therefore, in the above-mentioned granulation polymerization method, it is possible to dissolve or disperse the colorant in the polymerizable monomer and granulate the resin particles containing the colorant, but it is also possible to granulate resin particles containing the colorant. It is desirable not to add a coloring agent in order to obtain the desired result.

The resin fine particles for forming the intermediate coating layer have an average particle size of 0°05~
3 μm, preferably 0.1 to 1 μm, and a particle size distribution coefficient of variation of 20% or less, preferably 15% or less. Powders with an average particle diameter smaller than 0.05 μm are difficult to manufacture, and powders with an average particle diameter larger than 3 μm or a coefficient of variation larger than 20% make it difficult to coat the surface of the core particles with a film.

The coefficient of variation of particle size used in this specification represents a measure (%) of variation in particle size, and is the standard deviation (σ) of particle size divided by the average particle size.
It is obtained as follows. That is, first, photographs were taken with a scanning electron microscope, and 100 photographs were taken at random.
Select particles and measure their particle size. Based on this measurement result, the standard deviation (σ) and average particle size are determined. In addition,
The standard deviation (σ) used in the present invention is the square root of the square of the difference from the average value of each measured value divided by (n-1) when n particle diameters are measured. expressed.

That is, it is expressed by the following equation.

However, X8, X2, . . . The standard deviation (σ) obtained in this way was divided by the average particle diameter (X) and multiplied by 100, and the value was defined as the coefficient of variation.

In addition, the shape factor SF1 used in this specification is
It is used as a parameter indicating the difference (distortion property) between the major axis and minor axis of particles, and generally indicates the sphericity of powder particles, and is defined by the formula shown below. In addition,
Each value shown in this specification was measured using an image analyzer (Luzex 5000, manufactured by Nippon Regulator Co., Ltd.).

Area 4 (In the formula, area indicates the average value of the projected area of the powder, and maximum flame indicates the average value of the maximum flame in the projected image of the powder.) Therefore, the closer the particle shape is to a pearl, the more this Shape factor SF
The value of l is close to 100.

In addition, the amount of resin fine particles used when forming the intermediate coating layer is
The amount is 5 to 50 parts by weight, preferably 10 to 30 parts by weight, based on 100 parts by weight of the total weight of the core particles. That is, if the amount of resin forming the intermediate coating layer is less than 5 parts by weight, it will be difficult to completely cover the core particles with the intermediate coating layer.
The resin constituting the core particles leaches out, leading to toner aggregation.

When the core particles contain a colorant, the colorant component may be exposed on the surface of the toner particles, which may impede stable and uniform charging properties. On the other hand, if more than 50 parts by weight is used, a uniform intermediate coating layer cannot be formed.

The intermediate coating layer may contain a colorant, and the method for forming the intermediate coating layer containing the colorant on the surface of the core particle is as follows:
It is not particularly limited. For example, only a coloring agent is attached to the surface of a resin particle, which will become a core particle, in a wet or dry manner by the action of van der Waals force and electrostatic force, and then it is attached and fixed to the core particle by heat or mechanical impact force. Alternatively, it is also possible to attach and fix the colorant together with the resin particles, or to attach and fix the resin particles containing the colorant. In this case as well, the size of the particles may be within the same size range as the resin fine particles described above.

The coloring agent used in the electrostatic latent image developing toner of the present invention is not particularly limited, but various pigments and dyes of various colors as shown below can be used.

Specific examples of colorants that can be used in the present invention include yellow pigments such as yellow lead, zinc yellow, cadmium yellow, yellow iron oxide, Mineral 7 Asto Yellow Nickel Titanium Yellow, and Navels Yellow Naphthol Yellow S1 Hanq.
-Yellow G, Hansa Yellow LOG, Benzidine Yellow G.

There are benzidine yellow GR, quinoline yellow lake, permanent yellow, NCG, tartrazine lake, etc.

Light pigments include red yellow lead, molybdenum orange, permanent orange GTR, pyrazolone orange, palkan orange, industhrene brilliant orange RK1, benzidine orange G1, industhrene brilliant orange GK, etc.; red pigments include red pigment, cadmium red, red lead, Mercury sulfide cadmium, Permanent Red 4R, Lysole Red, Pyrazolone Red, Watching Red, Calcium Salt, Lake Red D1 Brilliant Carmine 6B1 Eosin Lake, Rhodamine Lake B1 Alizarin Lake, Brilliant Carmiso 3B, etc.; Purple pigments include Manganese Purple, Fast Violet B1 methyl violet lake, etc.; Blue pigments include navy blue, cobalt blue, alkali blue lake, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, partially chlorinated phthalocyanine blue,
Fast Sky Blue, Industhrene Blue BC, etc.: Green pigments include chrome green, chromium oxide, pigment green B1
Malachite Green Lake, Final Yellow Green G, etc.; White pigments include zinc white, titanium oxide, antimony white, zinc sulfide, etc.; Black pigments include furnace black, channel black, carbon black such as acetylene black, or activated carbon; non-magnetic Ferrite, etc. Extender pigments include palite powder, barium carbonate, clay, silica, white carbon, talc, alumina white, etc.

The above coloring agents may be used alone or in combination of two or more, and any coloring agent may be organic or inorganic, as long as it is non-polluting and has high coloring power, and is not limited to these.

These colorants can be used alone or in combination, but are used in an amount of 1 to 20 parts by weight, more preferably 1 to 1 liter, based on 100 parts by weight of the resin contained in the toner particles.
It is desirable to use O parts by weight. That is, if the amount is more than 20 parts by weight, the fixing properties of the toner will deteriorate, while if it is less than 1 part by weight, there is a risk that the desired image density may not be obtained.

The electrostatic image developing toner of the present invention is further coated with an intermediate coating layer. Since the coating layer is located on the outermost surface of the toner, the layer covering the intermediate coating layer is referred to as an "outer shell coating layer" in this specification.

The outer shell coating layer is made of styrene similar to the core particles and the intermediate coating layer.
Although it is formed from an acrylic copolymer resin, the proportion of styrene monomer units is lower than that of the resin constituting the intermediate coating layer.

Proportion S1 of styrene monomer units in the resin of the intermediate coating layer
(%) and the proportion of styrene monomer units in the outer shell coating layer resin is 52 (%), the difference (SI 32) is 5% or more, preferably 10% or more, more preferably 20%.
% or more is preferable.

The outer shell coating layer may be composed of a resin containing only acrylic seventh monomer units and not containing any styrene monomer units.

The toner obtained by forming the outermost shell coating layer from the resin described above becomes more suitable for positive chargeability.

The outer shell coating layer has good adhesion to the intermediate coating layer and is difficult to peel off. In addition, since it is compatible with the charging properties used, it is possible to impart uniform charging properties over a long period of time with good durability, and the resulting images are good with little fogging and the like. Even if a part of the outer shell coating layer peels off, since the lower intermediate coating layer is similarly composed of a styrene-acrylic copolymer resin, the effect will not be as great as exposing the polyester resin of the core particles.

Furthermore, when the outer shell coating layer is formed in this way, the chargeability, developability, heat resistance, gender etc. can be determined,
Even if the type, amount, etc. of the colorant contained in the core particles or intermediate coating layer change, stable and uniform chargeability can be imparted to each toner particle.

The outer shell coating layer is formed in the same manner as the intermediate coating layer using resin fine particles having a desired styrene content, and the coating layer may further contain a charge control agent if desired. .

In other words, the particle size is small compared to the core particle having the intermediate coating layer,
More specifically, fine particles of about 115 or less (i.e., fine resin particles, fine resin particles and charge control agent fine particles, or fine resin particles containing a charge control agent) are mechanically mixed at an appropriate blending ratio, and van der Waals force is applied. Preferred methods include a method in which fine particles are uniformly adhered around the intermediate coating layer by the action of electrostatic force, and then the fine particles are softened by a local temperature rise caused by, for example, an impact force to form a film. In the present invention, there is a difference in the content of styrene monomer units in the outer shell coating layer and the resin constituting the intermediate coating layer (i.e., a copolymer resin with a small proportion of styrene monomer units is different from a copolymer resin with a large proportion of styrene monomer units). Since there is a difference in the chargeability levels of the surface-constituting resins, it is possible to uniformly adhere the resin fine particles onto the surface of the intermediate coating layer. The fine resin particles for forming the outer shell coating layer used here have an average particle size of 0.05 to 3 μm, preferably 0.1 to lpm, and a coefficient of variation of particle size distribution of 20% or less, preferably,
15% or less is used. Average particle size is 0.05μ
A powder smaller than m is difficult to manufacture, and a powder larger than 3 μm or a coefficient of variation larger than 20% makes it difficult to coat the surface of the core particle with a film. According to such a method, the shape and particle size distribution of the core particles having the intermediate coating layer as described above are not substantially changed, and the softening point of the resin constituting the outer shell layer is higher than that of the resin constituting the intermediate coating layer. Even if the coating layer has a high surface resistance, it is possible to easily form an outer shell coating layer that substantially completely covers the outer surface of the intermediate coating layer. Furthermore, the surface properties of the toner particles obtained in this manner can be determined by selecting the composition and physical properties (particle size, thermal properties, gelling components, etc.) of the core particles and outer shell layer-forming particles, and by appropriately selecting the processing conditions. Improves smoothness and
Surface roughness can be changed. From the viewpoint of properties such as fluidity, cleanability, and chargeability of the toner particles, it is desirable that the toner particles be spherical and have minute irregularities on the surface. In addition, devices that can be suitably used in such a method include a hybridization system that applies a high-speed air impact method (manufactured by Nara Kikai Seisakusho Co., Ltd.), Ong Mill (manufactured by Honkawa Micron Co., Ltd.), and Mechanomill (manufactured by Kaida Seiko Co., Ltd.). )and so on.

However, the method for forming the resin coating layer is not limited to the above methods.

As a positive charge control agent, for example, nigrosine base EX
(manufactured by Orient Chemical Industry Co., Ltd.), quaternary ammonium salt P
-51 (manufactured by Orient Chemical Industry Co., Ltd.), Nigrosine Bontron N-01 (Orient Chemical Industry Co., Ltd.), Sudan Chief Schwarz BB (Solvent Black 3: Co1
or Index 26150), Fett Schwarz HBN (C, lN0.26150), Brilliant Spirits Schwarz TN (Falpen 7 Abritsken
(manufactured by Bayer AG), Zabonschwarz

These charge control agents can be used alone (or in combination), but the amount of charge control agent added to the outer shell coating layer is based on 100 parts by weight of the resin forming the outer shell coating layer. 0.1-10 parts by weight, preferably 0.5-10 parts by weight
It is 5 parts by weight. That is, if the amount added is less than 0.1 parts by weight, the amount of charge control agent present on the surface of the toner particles is small, resulting in insufficient charge of the toner, while if it exceeds 10 parts by weight, the resin This is because there is a risk that the charge control agent may peel off from the coating layer, become spent on the surface of the carrier, or be mixed into the developer, deteriorating printing durability.

In addition to the above-mentioned components, the acrylic yarn upper component constituting the outer shell coating layer may also include a 7-mer component having a nitrogen-containing polar functional group as shown below.

When a resin into which such a polar group is introduced is used for the outer shell coating layer, this resin itself acts as a charge control, so
It becomes possible to impart a certain degree of chargeability to the outer shell coating layer without particularly adding a charge control agent.

It is also possible to use homopolymers of the following monomer components, and the above effects can also be obtained by using resin fine particles of such polymers when forming the outer shell coating layer.

Nitrogen-containing polar functional groups are effective for positive charge control, and examples of seven polymers having nitrogen-containing polar functional groups include the following formula (1) (wherein, R3 is hydrogen or a methyl group, R2 and R1 are hydrogen or There is an amino(meth)acrylic seventh group represented by an alkyl group having 1 to 20 carbon atoms, X is an oxygen atom or a nitrogen atom, and Q is an alkylene group or an arylene group.

Representative examples of amino(meth)acrylic No. 7 polymers include:
N,N-dimethylaminomethyl (meth)acrylate,
N,N-diethylaminomethyl (meth)acrylate,
N,N-dimethylaminoethyl (meth)acrylate,
N,N-diethylaminoethyl (meth)acrylate,
N,N-dimethylaminopropyl (meth)acrylate, N,N-dimethylaminobutyl (meth)acrylate, p-N,N-dimethylaminophenyl (meth)acrylate, p-N.

N-diethylaminophenyl (meth)acrylate, p
-N,N-dipropylaminophenyl (meth)acrylate, p-N,N-'; 7-tylaminophenyl (meth)
Acrylate, p-N-laurylaminophenyl (meth)acrylate, p-N-stearylaminophenyl (
meth)acrylate, p-N, N-dimethylaminobenzyl (meth)acrylate, p-N.

N-diethylaminobenzyl (meth)acrylate, p
-N,N-dipropylaminobenzyl (meth)acrylate, p-N,N-dibutylaminobenzyl (meth)acrylate, p-N-laurylaminobenzyl (meth)
Examples include acrylate and p-N-stearylaminobenzyl (meth)acrylate.

Additionally, N,N-dimethylaminoethyl (meth)acrylamide, N,N-diethylaminoethyl (meth)acrylamide, N,N-dimethylaminopropyl (meth)
Acrylamide, N,N-diethylaminopropyl (meth)acrylamide, p-N,N-dimethylaminophenyl (meth)acrylamide, p-N,N-diethylaminophenyl (meth)acrylamide, p-N,N-dipropylaminophenyl (meth)acrylamide, p-N
, N-dibutylaminophenyl (meth)acrylamide, p N-laurylaminophenyl (meth)acrylamide, pN-stearylaminophenyl (meth)acrylamide, p-N, N-dimethylaminobenzyl (meth)acrylamide, p-N, N-diethylaminobenzyl (meth)acrylamide, p-N, N-dipropylaminobenzyl (meth)acrylamide, p-N.

N-dibutylaminobenzyl (meth)acrylamide,
Examples include p-N-laurylaminobenzyl (meth)acrylamide and p-N-stearylaminobenzyl (meth)acrylamide.

However, in the toner for developing electrostatic latent images of the present invention, it is not necessarily necessary to add such a charge control agent or the polar group-containing resin as described above. If the toner regulating blade is still a two-component type, the toner can be charged to a desired charge by using a carrier having a sufficient charge difference with the toner.

The toner for developing electrostatic latent images of the present invention has a laminated structure as described above, and exhibits stable charging properties, fixing properties, heat resistance, etc. High-quality images can be obtained with stable developability without causing problems such as fogging and toner scattering.

The present invention will be explained below using examples.

Production example of core particle ■ Polyester resin (M n =3800; Mw/M
n=2.8; Tr60°C, Tf=110°C) were sufficiently mixed in a ball mill and then kneaded on three rolls heated to 140°C. After cooling the kneaded material, it was coarsely ground using a feather mill and finely ground using a colander jet mill.

Next, air classification was performed to obtain a fine powder with an average particle size of 11 μm. The obtained fine particles are referred to as core particles (■).

Production example of core particle (2) In the production example of core particle (2), styrene-butyl acrylate-polyester graft copolymer (Mn□3200; Mw/Mn□8.7; T
The average particle size was 11 using the same composition and method as in the production example of core particles I, except that g-58°C, Tf = 105°C) was used.
A micron powder was obtained. The obtained fine particles are referred to as core particles (■).

Production example of core particle ■ In production example of core particle I, polyester resin (Mn=5
600; My/Mn=25; Tg=67°C, Tf
A fine powder with an average particle size of 11 pm was obtained using the same composition and method as in the production example of core particles (1) except that the core particles (120°C) were used. The obtained fine particles are referred to as core particles (■).

Method for producing fine resin particles In a polymerization reactor equipped with a stirrer, a condenser, and a thermometer, completely saponified polyvinyl alcohol and sodium dodecylbenzenesulfonate were added as emulsifiers to ion-exchanged water, and sodium persulfate was added as a polymerization initiator. 1
A mixture having the composition shown in the following was mixed, stirred, and subjected to emulsion polymerization under heating, and then granulated. Thereafter, the granules were coagulated using calcium chloride with several moisture groups. Subsequently, the coagulated material was washed with water, filtered, dried in vacuum, and then crushed using a jet pulverizer to obtain resin fine particles AN shown in Table 1.

The following evaluations were performed on each of the obtained fine particles, and the results are summarized in Table 1.

Measurement of number average molecular weight (Mn) and dispersity (Mw/Mn) Number average molecular weight and dispersity were measured by gel permeation chromatography under the conditions described below, and the values are calculated from a calibration curve created using standard polystyrene. Ta.

Detector: RID-300 differential refractometer (manufactured by JASCO Corporation) Column: A-80MX2 Temperature: 35°C Solvent: THF Flow rate: 1, Om+2/min Measured using flow tester CFT-500 manufactured by Shimadzu Corporation The melt viscosity was measured under conditions: nozzle: 1 m x 1 mm, temperature increase speed: 3° C./min, load: 20 kg/cm 2 , and the temperature at which the melt viscosity reached 106 voids was defined as the Tf value.

Glass transition temperature (Tg) The glass transition temperature (Tg) is a value measured using a differential scanning calorimeter 5SC1580DSC20 manufactured by Seiko Electronic Industries, Ltd.

Amount of Gelled Component The amount of gelled component indicates a resin component that is insoluble in toluene, and each amount shown in this specification is determined by the following measurement method. That is, the thermoplastic resin (Ms) [gl] to be measured is extracted using a Soxhlet extractor using a glass filter (G-3). In this way, the toluene soluble components in the resin are removed, and the weight [gl] of the insoluble components (Mr) is measured after drying. The weight percent of the insoluble component thus obtained was defined as the amount of gelled component.

Amount of gelling component (%) = (Mr/Ms)
Margin below) Upper blade 2■2■p! After preparing and mixing the core particles and resin particles obtained above with a coloring agent in the combinations and composition ratios shown in Table 2 below, the mixture was mixed in a Henschel mixer with a capacity of 10R rotating at 1500 rpm. The mixture was mixed and stirred for 2 minutes to adhere the resin fine particles and the colorant to the surface of the core particles.

Next, 150 g of the obtained mixture was added to a hybridizer-Nl
It was charged into a Model 2-1 (manufactured by Nara Kikai Seisakusho Co., Ltd.) and processed for 8 minutes at room temperature at a circumferential blade speed of 78 m/sec.
A uniform intermediate coating layer containing a colorant was formed on the surface of the core particles.

Subsequently, resin fine particles and charge control agent were added according to Table 2 below.
Other than those prepared and mixed in the combinations and composition ratios shown in
By performing the same treatment as in the formation of the intermediate coating layer, an outer shell coating layer containing a charge control agent was formed, and toners 1 to 2 shown in Table 2 were obtained.

(Hereinafter, blank 5 Manufacturing components of the carrier Parts by weight Polyester resin 100 (Softening point 123°C1 Glass transition point 65°C, AV23.0HV40) Fe-Zn ferrite fine particles 500MFP-
2 (manufactured by TDK) - Carbon black 2 (manufactured by Mitsubishi Chemical Industries, Ltd., AM#8) The above materials were thoroughly mixed and pulverized using a Henschel mixer, and then the cylinder part was heated at 180°C and the cylinder head part was heated at 170°C.
The mixture was melted and kneaded using an extrusion kneader set at °C. After the mixed wire was left to cool, it was coarsely pulverized using a feather mill, further finely pulverized using a jet mill, and then classified using a classifier to obtain a carrier having an average particle size of 60 μm.

〔Evaluation methods〕

The obtained toners ① to ② were evaluated for various properties as described below. In addition, each toner is 1, toner 10
0 parts by weight of colloidal silica R-972 (manufactured by Nippon Aerosil Co., Ltd.) with 0.1 parts by weight was used for evaluation of various properties. The results are shown in Table 3.

1. Content rate of poorly charged toner (weight %) Toners ■ to ■ are mixed with the above carrier and toner/carrier 7
/93 for 30 minutes to prepare a two-component developer. For this developer, plain paper copy IIEP-470
Z (manufactured by Minolta Camera Co., Ltd.) was used to measure the change in weight percent of the poorly charged toner contained in the toner after initially copying 50,000 copies and 100,000 copies.

The amount of defective charge amount toner was measured as follows. First, approximately 1 g of developer is sampled from five locations in the developing device. For this developer, November 28, 1986
At the 58th Research Conference sponsored by the Electrophotographic Society held on the same day, the toner charge distribution was measured using a device presented by Yoita et al. of Minolta Camera Co., Ltd. The details of the principle are described in the materials distributed at the same research discussion group, and will be briefly explained here. Figure 1 shows its structure.

The rotational speed of the magnet roll (3) is set to 1100 rpm, and 3 g of developer is weighed using a precision balance and placed uniformly over the entire surface of the conductive sleeve (2). Next, set the bias voltage from the bias power supply (4) to θ~l 'OK.
Apply V sequentially, rotate the sleeve (2) for 5 seconds, and read the potential Vm when the sleeve (2) is stopped. At this time, the weight Mi of the separated toner (7) attached to the cylindrical electrode (1) is measured using a precision balance, and in this way, the average charge amount of each applied voltage is determined. By totaling these, it is possible to measure the charge amount distribution of the toner contained in the developer.

In the charge amount distribution obtained in this way, the amount of toner (weight %) that is 1/2 or less of the average charge amount of the toner is determined, and this value is taken as the content rate (weight %) of the poorly charged toner.

2. Image quality evaluation After measuring the content of the toner with poor charging, Dataquest's standard chart was copied under appropriate exposure, and the toner fog on the image in the white background was visually evaluated and ranked. Although it is practically usable with a rank of Δ or higher, a rank of ○ or higher is preferable.

3. Image Density Charge Failure The density of the solid portion of the initial image at the time of measuring the toner content was measured using a Sakura densitometer.

4. Improper charging in the half-density area In the initial image when measuring the toner content, the texture in the half-density area (solid cyan color area on the chart) was visually evaluated and ranked.

A rank of Δ or higher is practically usable, but a rank of 0972 or higher is preferable.

(Hereinafter referred to as blank space) Effects of the Invention The toner for developing electrostatic images of the present invention does not generate poorly charged toner, has excellent durability and stability, and forms high-quality images without background fogging. can.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a schematic configuration of a charge amount distribution measuring device. Patent applicant Minolta Camera Co., Ltd.

Claims (1)

[Claims] 1. In a toner for developing an electrostatic image having a laminated structure comprising a core particle, an intermediate coating layer and an outer shell coating layer laminated in this order on the core particle, the core particle is composed of a polyester resin,
The intermediate coating layer and the outer shell coating layer are composed of a styrene-acrylic copolymer resin, and the styrene monomer content of the styrene-acrylic copolymer resin is lower in the outer shell coating layer than in the intermediate coating layer. Chargeable toner.