JP3021178B2 - Toner for electrostatic image development - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner for developing an electrostatic image formed in electrophotography, electrostatic printing, electrostatic recording and the like.

[0002]

2. Description of the Related Art In general, a toner for developing an electrostatic image is composed of a resin component, a colorant component composed of a pigment or a dye, and additional components such as a release agent and a charge control agent.
As the resin component, a natural or synthetic resin is used alone or in an appropriate mixture. Many improvements have been made to the resin components of toners suitable for the dry development system, which have been rapidly developed in recent years. In particular, in an electrophotographic copying machine intended for high-speed copying, a heating roll is used.
The toner image obtained by development on an electrostatic recording medium (photosensitive drum) is temporarily transferred to a transfer sheet such as paper by adopting a color fixing method.
After transfer to the sheet, the transfer sheet is passed through a fixing roller that performs heat and pressure bonding to fuse the toner image to the sheet, thereby fixing the sheet.

[0003] Various fixing methods are known. In particular, a contact heat fixing method represented by a heat roller fixing machine is compared with a non-contact heat fixing method such as a hot plate fixing device. This is excellent in that the thermal efficiency is high, and is particularly preferable in that high-speed fixing is possible.

In this contact heating fixing system, toner
From the viewpoint of the physical properties of the binder resin, copy speed, power consumption, maintenance of the image forming apparatus and other workability.
Fixing is performed within a temperature range of 150 to 220 ° C.

Therefore, in the toner used in this fixing method, a low molecular weight polymer is added to the binder resin so that the fixing is reliably achieved at the fixing temperature.
It is considered preferable that the binder resin contains a high molecular weight polymer to increase the toner elastic modulus so as to reduce the viscosity and prevent the offset phenomenon caused by the partial adhesion of the toner to the contact heating roller. ing.

[0006] In electrophotographic copying machines intended for high-speed copying, a so-called two-component dry developer comprising a mixture of carrier particles and toner particles is often used. In this two-component dry developer, fine toner particles are held on the surface of relatively large carrier particles by an electric force generated by friction between the two particles. The attracting force of the toner particles in the direction of the latent image due to the electric field generated by the image overcomes the bonding force between the toner particles and the carrier particles, and the toner particles are attracted and adhered on the electrostatic latent image, and the electrostatic latent image is formed. The image is to be visualized. The developer is used repeatedly while replenishing the toner consumed by the development.

Therefore, the carrier must be triboelectrically charged to a desired polarity and to a sufficient charge amount at all times during use for a long period of time. However, in a conventional developer, a toner film is formed on the carrier surface by mechanical collisions such as collisions between particles or collisions between particles and a developing device or heat generated by these collisions, so-called spent occurs, and further, toner particles are formed. When the external additives such as silica added to the surface of the toner are separated or buried, the charging characteristics and the flow characteristics of the toner and the carrier deteriorate with the use time, and it is necessary to replace the entire developer. Occurs.

In order to prevent such deterioration of the developer and to always obtain a stable charge amount during use for a long period of time, a method of coating the carrier surface with various resins has been proposed, but it is still satisfactory. Nothing to go for.

Particularly, in a toner for an electrophotographic copying machine intended for high-speed copying, a large amount of a low-molecular-weight polymer is used so as to achieve a reliable fixing property, and it is stronger in a high-speed developing apparatus. The developer is liable to be degraded due to spent and toner surface changes due to mechanical collision or the like.

Furthermore, in high-speed copying, the number of copies increases and the toner consumption per machine increases. Therefore, it is desirable to prevent the deterioration of the developer and to reduce the number of maintenance operations for replacing the entire developer. Mareta.

Even if the required properties are only the fixing property and the non-offset property, it is not sufficient that the binder resin simply contains a high molecular weight polymer and a low molecular weight polymer. In addition, it is necessary that these polymers be compatible with each other and be contained in the binder resin in a state of being completely integrated with each other. For example, when the toner is manufactured, stored, or image-formed. It is required that they are not separated.

This is because the fixing property of the low molecular weight polymer and the non-offset property of the high molecular weight polymer are simultaneously exhibited only in such a state. This is because the intended effect cannot be obtained as a toner because the individual effects are exhibited.

[0013]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and aims at non-offset properties, fixing properties, pulverizability during production, and resistance to storage. An electrostatic image developing toner having good properties in blocking properties (non-aggregating properties) and developability during image formation.
To provide.

Another object of the present invention is to provide a developer containing a carrier, the surface of which is coated with a resin, while keeping the toner spent on the carrier and maintaining a high effect of preventing the developer from deteriorating due to a change in the surface of the toner. Even when used for a long time, the charge amount distribution is narrow, and the occurrence of reverse charging toner, image quality deterioration,
The purpose of the present invention is to provide a developer for electrostatic latent images free from background contamination.

Another object of the present invention is to provide a developer capable of always forming a stable image by suppressing a change in toner charge due to an environmental change, for example, a humidity change. Generally, the charge amount is high when the humidity is low and becomes low when the humidity is high, thereby changing the quality of the image. However, the developer of the present invention has improved such disadvantages.

[0016]

According to the present invention, there is provided a toner for developing an electrostatic image mainly comprising a binder resin and a colorant, wherein the binder resin is

(A) GPC molecular weight peak Lp is 1.5 × 10 ³ to 4 × 1
0 ³ and its weight average molecular weight (Mw) / number average molecular weight (M
n) is a styrene homopolymer of less than 4.0, a low molecular weight polymer

(B) GPC molecular weight peak Mp is 3 × 10 ^{4 to} 5 × 10 ⁵
And a medium molecular weight polymer which is a styrene-alkyl (meth) acrylate copolymer.

(C) An insoluble infusible high molecular weight polymer which is a crosslinked styrene homopolymer or a crosslinked styrene-alkyl (meth) acrylate copolymer.

(A) per 100 parts by weight of the total of the low molecular weight polymer (a) and the insoluble infusible high molecular weight polymer (c)
Is more than 60 and less than 80 parts by weight, (c) is more than 20 parts by weight and less than 40 parts by weight,

The insoluble infusible high molecular weight polymer (c) 100
A toner for developing an electrostatic image, wherein the content of the medium molecular weight polymer (b) is 5 to 60 parts by weight with respect to parts by weight, and the THF-insoluble content of the binder resin is more than 70 and 98% or less.

A toner for developing an electrostatic image, wherein the acid value of the binding resin is 0.1 to 2.0 KOH mg / g, is preferable.
The particle size of the insoluble infusible polymer (c) is 0.03 μm to 1 μm
It is more preferable that the low molecular weight polymer (a) is a low molecular weight polymer obtained by bulk polymerization in a system substantially free of a solvent.
(a) is preferred.

Further, a toner for developing an electrostatic image, wherein the toner for developing an electrostatic image is suitable for a developer using a carrier having a resin coating layer, is preferable.

As described above, the toner for developing an electrostatic image according to the present invention has a lower minimum temperature at which the toner can be fixed and good fixability as compared with the conventional toner, and has excellent non-offset without impairing the toner. With good resistance to blocking, good pulverizability during production, good triboelectricity, and excellent developability.Moreover, the developer using a carrier having a resin coating layer is less likely to deteriorate the developer. It has excellent performance that is unlikely to occur and has great durability when used repeatedly.

The styrene-based component for obtaining the styrene-based homopolymer (a) serving as the structural unit of the binder resin is a so-called styrene-based monomer, and specific examples thereof include styrene and o-methyl. Styrene, m-methylstyrene, p-methylstyrene, α-methylstyrene,
p-ethylstyrene, 2,4-dimethylstyrene, pn
-Butylstyrene, p-tert-butylstyrene, pn
-Hexylstyrene, pn-octylstyrene, p-
n-nonylstyrene, pn-decylstyrene, pn
-Dodecylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene and the like can be mentioned, among which styrene is most preferred. A styrene homopolymer is obtained by using the above styrene monomers alone or as a mixture.

In order to obtain the styrene-alkyl (meth) acrylate copolymer (b), the styrene-based monomer can be used. What gives the first acrylic component and the second acrylic component constituting the binding resin together with the styrene component is a so-called acrylic monomer, and specific examples thereof include alkyl acrylate and methacrylic acid. Examples of the alkyl ester include methyl acrylate, ethyl acrylate,
N-butyl acrylate, isobutyl acrylate, ethyl hexyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, lauryl methacrylate, stearyl methacrylate, and the like, and particularly n-butyl acrylate, acrylic Ethylhexyl acrylate, n-butyl methacrylate and lauryl methacrylate are preferred.

The acrylic component may have a glass transition temperature in the range of 40 ° C. to 80 ° C. of a copolymer obtained by polymerizing the acrylic component with the monomer of the styrene component under ordinary conditions. Preferably, and more preferably, the glass transition temperature is in the range of 50C to 70C. However, the glass transition temperature of the medium molecular weight polymer (b) is not limited to this.

The “insoluble and infusible” of the insoluble and infusible high molecular weight polymer (c) as a preferred example of the binder resin is “insoluble” and refers to “infusible”. Here, "insoluble" refers to AFTM-407-02 (automotive paint test method in the United States). A resin press-molded test piece is wrapped in a 300-mesh wire net and heated in acetone for 7 hours under reflux to remove the insoluble resin. Is initially 90% or more per weight, preferably
95% or more. On the other hand, "infusible" means that the acetone-insoluble resin component has a diameter of 0.5% when a load of 10 kg is applied at 200 ° C. with a descending flow tester (manufactured by Shimadzu Corporation). × 1m
/ m nozzle means that the amount melted for the first minute is less than 1 mm.

The insoluble and infusible high molecular weight polymer (c) has a crosslinking agent as a component, and such a crosslinking agent is a compound mainly having two or more polymerizable double bonds. Aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, aryl methacrylate Diethylenic carboxylate, N, N-divinylaniline,
Examples include divinyl ether and divinyl sulfide. Divinylbenzene, ethylene glycol dimethacrylate
And 1,6-hexanediol diacrylate are preferably used.

The amount of the crosslinking agent is preferably from 0.01 to 2% by weight of the monomers constituting the insoluble infusible high molecular weight polymer (c), more preferably from 0.02 to 1% by weight, particularly preferably from 0.02 to 1% by weight. Preferably, those having a content of 0.04 to 0.8% by weight are suitably used.

The low molecular weight polymer (a) used in the present invention
Is a styrene-based homopolymer containing 100% by weight of a styrene-based monomer.
100% by weight styrene homopolymer.

The medium molecular weight polymer (b) is preferably a styrene containing 30 to 90% by weight of styrene and 70 to 10% by weight of alkyl acrylate and / or alkyl methacrylate as monomer units. -(Meth) acrylic acid alkyl ester copolymers, particularly preferred examples being those of 50-90% by weight of styrene and 50-20% by weight of n-butyl acrylate.

The insoluble infusible high molecular weight polymer (c) is preferably 50 to 100% by weight of styrene, 50 to 0% by weight of an alkyl acrylate and / or alkyl methacrylate, and 0.01 to 2% of a crosslinking agent. Weight% (the sum of the three
A styrene homopolymer or a styrene- (meth) acrylic acid alkyl ester copolymer containing 100% by weight) as a monomer unit. Particularly preferable examples are 60 to 90% by weight of styrene. %, Methacrylic acid n
5 to 20% by weight of butyl, 30 to 10% by weight of n-butyl acrylate and 0.01 to 2% by weight of a crosslinking agent (the sum of the four becomes 100% by weight).

Further, those having more than 60 parts by weight of the low molecular weight polymer (a) and more than 20 parts by weight and less than 40 parts by weight of the insoluble infusible high molecular weight polymer (c) are preferably used (however, The total of the molecular weight polymer (a) and the insoluble infusible high molecular weight polymer (c) is
100 parts by weight) and insoluble and infusible high molecular weight polymer
(c) 100 parts by weight, the medium molecular weight polymer (b) is preferably in the range of 5 to 50 parts by weight, more preferably the medium molecular weight polymer (b) is 10 to 40 parts by weight. It is preferably used.

When the amount of the low molecular weight polymer (a) is 60 parts by weight or less (the amount of the insoluble infusible high molecular weight polymer (c) is 40 parts by weight or more), the offset resistance is good, but the fixing property in the low temperature region is good. Is unsatisfactory and the minimum fixing temperature increases. When the amount of the low molecular weight polymer (a) is more than 80 parts by weight (the amount of the insoluble infusible high molecular weight polymer (c) is less than 20 parts by weight), the fixing property is good, but hot offset tends to occur, The fixing temperature range becomes narrow, which is not preferable.

It is difficult to obtain the desired effect only by satisfying the preferred ranges of the low molecular weight polymer (a) and the insoluble infusible high molecular weight polymer (c). It is more preferable that the polymer is filled with a mixed resin in which the molecular weight polymer (a), the medium molecular weight polymer (b), and the insoluble infusible high molecular weight polymer (c) are uniformly compatible and dispersed.

When the amount of the medium-molecular-weight polymer (b) is less than 5 parts by weight based on 100 parts by weight of the insoluble and infusible high-molecular-weight polymer (c), the fixing property is good but hot offset occurs. This is not preferable because the fixing temperature range is narrowed.
Further, the obtained toner becomes brittle, and tends to be spent on the carrier and miniaturize the toner. When the toner is used for a long period of time, toner scattering from the carrier and toner fogging in a blank space increase.

When the amount of the medium-molecular-weight polymer (b) is more than 50 parts by weight based on 100 parts by weight of the insoluble and infusible high-molecular-weight polymer (c), the offset resistance is good but the fixing in the low-temperature region is good. The property becomes poor, and the minimum fixing temperature rises, which is not preferable.

The GPC molecular weight peak Lp of the low molecular weight polymer (a) is
1.5 × 10 ³ to less than 4 × 10 ³ , preferably 2 × 10 ^{3 to} 3.5 × 10 ³
The low-molecular-weight polymer (a) having a weight average molecular weight (Mw) / number average molecular weight (Mn) of less than 4.0 is preferably used.

The GPC molecular weight peak Lp of the low molecular weight polymer (a) is
When it is lower than 1.5 × 10 ³ , the fixability is good, but the toner easily aggregates in the developing machine, and the life of the developer is short. Further, the storage stability of the toner is poor, and the toner hardens during high-temperature storage. On the other hand, when the molecular weight peak Lp is higher than 4 × 10 ³ , spent and miniaturization are unlikely to occur, but the fixability in a low temperature region becomes poor, the minimum fixing temperature rises, and the cold offset temperature also increases. It is not preferable because it is defective.

The GPC molecular weight peak Mp of the medium molecular weight polymer (b) is
3 × 10 ^{4 to} 5 × 10 ^5, preferably 5 × 10 ^{4 to} 5 × 10 ⁵ , more preferably 8 × 10 ⁴ to 4 × 10 ⁵ are suitably used.

The GPC molecular weight peak Mp of the medium molecular weight polymer (b) is
If it is lower than 3 × 10 ⁴ , the fixing property is good, but hot offset is apt to occur, and the fixing temperature range is undesirably narrow. Further, it is considered that the compatibility effect between the low molecular weight polymer (a) and the insoluble infusible high molecular weight polymer (c) is due to the joining effect of the medium molecular weight polymer to the low molecular weight polymer (a). Since each polymer of the fusible high molecular weight polymer (c) exerts an individual action, the obtained toner becomes brittle, and tends to be spent on a carrier and to be refined, and it is difficult to use the toner for a long time. When used, toner scattering from the carrier and toner fogging in the margins increase. If the GPC molecular weight peak Mp of the medium molecular weight polymer (b) is higher than 50 × 10 ⁴ , the offset resistance is good, but the fixability in the low temperature region becomes poor, and the fixing lower limit temperature is undesirably increased.

[0043]

Further, those having a glass transition temperature (Tg) of the medium molecular weight polymer (b) of 0 ° C. to 70 ° C. and a softening point of the falling type flow tester of 80 ° C. to 160 ° C. are preferably used. It is more preferable that the Tg is 20 ° C to 55 ° C and the softening point is 90 ° C to 150 ° C.
Are preferably used.

When the Tg is higher than 70 ° C. and the softening point is higher than 160 ° C., the anti-offset property is good, but the fixability in a low temperature region tends to be poor, and the fixing lower limit temperature tends to increase, which is not preferable. There is. When the Tg is lower than 0 ° C. and the softening point is lower than 80 ° C., the fixing property is good, but hot offset tends to occur easily, and the fixing temperature range tends to be narrow. Further, the preservability of the toner tends to deteriorate.

If the acid value is lower than 0.05 KOH mg / g, it is considered that the resistance of the resin which is the main component of the toner is high. However, the charging characteristics of the carrier and the toner change with the use time, and stable development is achieved. There is a tendency that the agent cannot be obtained. Also, the acid value
If it is more than 2.0 KOHmg / g, the polarity of the resin becomes large, and it tends to be difficult to obtain a desired charge amount of the carrier and the toner. Preferably, the acid value is 0.1 to 2.0 KOHmg
/ G is preferably used.

The toner for developing an electrostatic image obtained according to the present invention is obtained by a developing method using a so-called two-component developer in which a carrier made of iron powder or glass beads is mixed with the toner. It is suitably used for a developer using a carrier having the following formula.

Further, the toner of the present invention is not limited to a two-component developer, but may be a one-component developer using no carrier, for example, a magnetic one-component toner containing magnetic powder in the toner. Also, the present invention can be applied to a non-magnetic one-component toner containing no magnetic powder in the toner.

A typical carrier having a resin coating layer is a carrier in which the surface of core particles made of iron, nickel, ferrite, or glass beads is coated with a coating layer of an insulating resin. As a resin material, generally, a fluorine resin, a silicone resin, an acrylic resin,
Styrene acrylic copolymer resins, polyester resins, and polybutadiene resins are typical.

When a developer containing the toner for developing an electrostatic image obtained according to the present invention and a carrier having a resin coating layer is used, the spent particles adhere to the surface of the carrier particles and become contaminated. It is particularly suitable for a high-speed electrophotographic machine in that the frictional charge characteristics between the carrier and the toner can be controlled and the durability is excellent and the service life is long.

The main component resin of the binder resin of the present invention can be synthesized, for example, by the following method. That is, a low molecular weight polymer (a) and a medium molecular weight polymer (b) are synthesized by generally known polymerization methods, that is, bulk polymerization, suspension polymerization, solution polymerization, etc. It can be obtained by melt-mixing the insoluble and infusible high molecular weight polymer (c) synthesized by a synthetic method, a suspension polymerization method, a solution polymerization method or the like.

The low molecular weight polymer (a) is preferably obtained by bulk polymerization in a system substantially free of a solvent, a dispersant, an emulsifier, etc., since the toner has a particularly high charge retention property.

The insoluble infusible high molecular weight polymer (c) preferably has a particle diameter in the range of 0.03 μm to 1 μm,
It is excellent in compatibility and dispersibility with (a) and the medium-molecular-weight polymer (b), and particles obtained by emulsion polymerization are preferably used.

The feature of the above synthesis method is that in the synthesis process, the low molecular weight polymer (a), the medium molecular weight polymer (b) and the insoluble infusible high molecular weight polymer (c) are uniformly mixed, Due to the presence of the medium molecular weight polymer (b), the low molecular weight polymer (a)
And insoluble and infusible high molecular weight polymer (c).

The mixed resin in which three polymers of the low molecular weight polymer (a), the medium molecular weight polymer (b), and the insoluble infusible high molecular weight polymer (c) are uniformly compatible and dispersed is It can be confirmed by "Method for estimating gel content".

The "method of estimating the gel content" means that a polymer component which has been crosslinked into a solvent (for example, insoluble and infusible) in a resin composition has a low molecular weight polymer in a mixed resin. When a matrix is combined with a medium-molecular-weight polymer and affects the dissolution rate of the soluble component, the polymerization rate of the polymer component that has become soluble in the solvent by extraction for a certain period of time is determined, so that the three polymers can be dissolved. It can be used as a parameter indicating the degree of the state of uniform miscible dispersion. The value measured by the following method is defined as tetrahydrofuran (hereinafter abbreviated as THF) insoluble matter.

That is, about 1 g of the resin was weighed (W
₁ [g]), put in a thimble filter paper (No. 86R made by Toyo Roshi Kaisha), apply to a Soxhlet extractor, extract with 100 to 200 ml of THF as a solvent for 6 hours, and concentrate the soluble components extracted by the solvent. After drying at 100 ° C. for several hours, the amount of the soluble resin component is weighed (W ₂ [g]) and calculated according to the following equation.

THF insoluble content = (W ₁ −W ₂ ) / W ₁ × 10
0 [%] In the mixed resin obtained by uniformly dispersing the three polymers obtained in the present invention, the THF-insoluble content is preferably more than 70 to 9%.
8%, more preferably 75-95% is suitably used.

When the THF-insoluble content is 70% or less, the homogeneously compatible dispersion state is poor, hot offset is likely to occur, and the fixing temperature range is undesirably narrow. On the other hand, if the THF-insoluble content is higher than 98%, the crosslinking density becomes too high, and the fixability becomes poor, which is not preferable.

The toner for developing an electrostatic image according to the present invention is also provided.
In addition, a suitable pigment or dye is blended as a colorant, and if necessary, a charge control agent and other types of toner additives such as a releasing agent and a magnetic substance can be blended to improve fluidity. An external additive such as a cleansing agent or a cleaning aid can be applied to the toner surface.

In addition to the main binder resin, other styrene resins, polyester resins, etc. may be blended and used as an auxiliary resin.
% By weight or less is preferred.

The toner is prepared by mixing the above-mentioned additives with the main resin component, uniformly mixing and melting the mixture, cooling the mixture, crushing the mixture if necessary, pulverizing the mixture with a jet mill or the like, and then classifying the mixture with a classifier. Thereby, a final product (toner) having a desired particle size distribution having an average particle size of 3 to 30 μm can be obtained.

Each test method used in the present specification is described below. [Molecular Weight Measurement Method] The molecular weight at the peak position of the molecular weight distribution was determined by using a gel permeation chromatography (GPC) equipped with a column (3 GMHs manufactured by Tosoh Corporation) using tetrahydrofuran (THF). ) Was dissolved at a concentration of 0.2 wt%, and measurement was performed at a temperature of 20 ° C. at a flow rate of 1 ml / min. When measuring the molecular weight of the sample, a measurement condition was selected in which the logarithm of the molecular weight and the count number of the calibration curve prepared from several types of monodisperse polystyrene standard samples were linear.

[Acid Value Measurement Method] A resin sample (400 mg) was weighed, acetone (50 ml) was added thereto, and dissolved in an N ₂ gas atmosphere. Then, a phenolphthalene indicator solution (1% ethyl alcohol solution) was added to the solution.
Two drops were added, and titration was performed with 1 / 100N N ₂ OH in an N ₂ gas atmosphere, and the acid value was calculated from the following equation.

Acid value [KOHmg / g] = [(x−B) × f × 56.11
× 0.01] ÷ Sample collection amount f: Factor of 1 / 100N N ₂ OH specified solution-x: Sample titer [ml] B: Blank test titer [ml]

[Measurement Method of Softening Point] 1 g of a resin sample was weighed and measured with a Shimadzu Flow Tester CFT500 under the conditions of a nozzle 1 × 10 mm, a load of 30 kg, and a heating rate of 3 ° C./min. The temperature at the midpoint of the distance from to the end was taken as the softening point.

[Glass Transition Point (Tg)] The measurement was carried out in a differential scanning calorimeter, Shimadzu DSC-30, in a N ₂ gas atmosphere at a temperature rising rate of 10 ° C./min, and the shoulder was defined as Tg.

[Copy Test] Fixability Test (Offset Property and Minimum Fixing Temperature) A commercially available electrophotographic copying machine was modified (the photoconductor was an OPC photoconductor, the rotation speed of the fixing roller was 450 mm / sec, The image formation was performed using a heater in which the heat roller temperature in the fixing device was made variable and the oil coating device was removed. Fixing temperature 120 ℃
The temperature was controlled to about 230 ° C., and the fixing property and offset property of the image were evaluated.

Here, the minimum fixing temperature means that the bottom surface is swept.
A load of 500 g was placed on the fastness tester covered with the cover, and the image fixed through the fixing device was rubbed five times back and forth, and before and after rubbing, the optical reflection density was measured with a Macbeth reflection densitometer. Means the temperature of the fixing roller when the fixing rate exceeds 70%.

Fixing ratio = (image density after rubbing / image density before rubbing) × 100% Further, as a finger rubbing test, a halftone fixed image portion is bent, and the edge portion thereof is touched with a finger. This refers to the temperature of the fixing roller when there is no rubbing or stain on the fixed image.

The term "offset" refers to the evaluation of the presence or absence of image fouling on the fixing roll at a fixing temperature of 230 ° C.

Fogging on Paper In the copying test, the fogging of the toner on the background (margin) was measured using a Minolta CR-200 colorimeter. When the fog is small, the value is 0.5% or less, and when the fog is large, the value is 1% or more.

Storage stability Regarding the storage stability, the degree of occurrence of aggregation when each toner was allowed to stand in a constant temperature bath at 50 ° C. for 24 hours was evaluated.

[Medium molecular weight polymer (b), Production Example-1] styrene (st) 7.3 kg butyl acrylate (BA) 2.7
kg, 22 g of benzoyl peroxide and mixed and dissolved.
20 kg of an aqueous solution of deionized water in which 10 g of polyvinyl alcohol (gothanol KH-17) was dissolved was added, and the inside of the polymerization machine was heated to 85 ° C. with stirring and the polymerization reaction was carried out for 10 hours to obtain a molecular weight peak. A medium molecular weight polymer having a glass transition point (hereinafter, abbreviated as Tg) of 54 ° C and a softening point of 142 ° C was obtained at 26 × 10 ⁴ .

[Medium molecular weight polymer (b), Production Example-2] 7.0 kg of styrene, 3.0 kg of butyl acrylate and 65 g of benzoyl peroxide were charged into a 50-liter polymerization machine, mixed and dissolved, and then polyvinyl alcohol (go). 20 kg of an aqueous solution of deionized water in which 10 g of phenol KH-17 was dissolved, and the inside of the polymerization machine was heated to 90 ° C. with stirring to carry out a polymerization reaction for 10 hours to give a molecular weight peak of 12 × 10
^{In 4} , a medium molecular weight polymer having a Tg of 47 ° C and a softening point of 123 ° C was obtained.

[Medium molecular weight polymer (b), Production Example-3] 6.8 kg of styrene, 3.2 kg of butyl acrylate and 31 g of benzoyl peroxide were charged into a 50-liter polymerization machine, mixed and dissolved, and then polyvinyl alcohol (go). -Kenol KH-17) was added with 20 kg of an aqueous solution of deionized water in which 10 g was dissolved, and the inside of the polymerization machine was heated to 90 ° C. with stirring to carry out a polymerization reaction for 10 hours to give a molecular weight peak of 19 × 10 5
^{In 4} , a medium molecular weight polymer having a Tg of 41 ° C. and a softening point of 122 ° C. was obtained.

[Example 1] [Preparation of low molecular weight polymer (a)] 100 parts of styrene (St) 0.3 part of di-t-butyl peroxide were stirred in an autoclave at 220 ° C for 6 hours. After the polymerization, the unreacted monomer was recovered under reduced pressure to obtain a low molecular weight polymer having a molecular weight peak of 3,600 and Mw / Mn of 2.7.

[Preparation of Insoluble and Infusible High Molecular Weight Polymer (c)] Styrene (St) 77 parts Butyl acrylate (BA) 23 parts Divinylbenzene 0.1 part At least 100 parts of water A nonionic emulsifier (Emulgen 950) 1 part Anion emulsifier (Neogen R) 1.5 parts Potassium persulfate 0.2 part

And stirred at 80 ° C. for 8 hours.
After polymerizing for an hour, it was dried at 45 ° C. to obtain a fine particle resin powder having a particle diameter of 0.2 μm. The obtained polymer had an insoluble content of 96% in the test of AFTM-407-02 and an insoluble infusible high molecular weight of 0.9 mm in the descending flow tester test. It was united.

Subsequently, the finely pulverized low molecular weight polymer
(a) 64.2 parts and the medium molecular weight polymer (b) 10.2 obtained in Production Example-1
Was mixed with 25.6 parts of the insoluble infusible high molecular weight polymer (c) fine powder, and the mixture was melt-kneaded at 200 ° C. with a twin-screw extruder to obtain a mixed resin which was uniformly compatible and dispersed.

(Preparation of Toner) 100 parts by weight of the mixed resin homogeneously dispersed and dispersed above, 6 parts by weight of carbon black (MA-100), 2 parts by weight of polypropylene wax (550P), and a nigrosine dye (N -01) 2 parts by weight were pulverized and mixed in a ball mill, and then kneaded well with a hot roll at 140 ° C for 30 minutes.

After cooling, the mixture was roughly crushed by a hammer mill and then finely crushed by a jet mill. Further, the obtained finely pulverized powder is classified with an air classifier to obtain particles of 5 to 20 μm, and then 0.2 parts by weight of hydrophobic silica (R-972) is added and mixed, and toner having an average particle diameter of 10 μm is added. -Was obtained.

A copy test was conducted with a commercially available copying machine using the toner and the silicon resin-coated carrier. As a result, the image could be fixed from 145.degree. C., and even at 230.degree. There was no stain and even after copying 100,000 sheets, no toner spent on the carrier, and a clear image free of stain and fog was obtained as in the initial stage. Other test results are shown in Table 1. All parts are by weight.

(Measurement of THF-Insoluble Content) The THF-insoluble content of the mixed resin obtained in Example 1 was 78.1%, and the mixed resin was uniformly compatible and dispersed.

[0085]

[0086]

[0087]

Example 2 In the same manner as in the preparation of the low molecular weight polymer (a) of Example 1, 100 parts of styrene (St) and 0.4 part of di-tert-butyl peroxide were polymerized to give a polymer having a molecular weight peak of 3,200. A low molecular weight polymer having Mw / Mn of 2.9 was obtained.

Insoluble infusible high molecular weight polymer of Example-1
In the same manner as in the preparation of (C), styrene (St) 77 parts Butyl acrylate (BA) 13 parts Butyl methacrylate (BMA) 10 parts Ethylene glycol dimethacrylate 0.2 part of a monomer mixture was polymerized, and the AFTM test was insoluble. An insoluble and infusible high molecular weight polymer having a melting point of 96% and a melt amount of 0.4 mm was obtained.

Subsequently, the above-mentioned low molecular weight polymer pulverized
(a) 59.0 parts, and the medium-molecular-weight polymer obtained in Production Example-3 (b) 5.7
Part and 35.3 parts of the high-molecular-weight polymer (c) fine powder were melt-mixed to obtain a mixed resin which was uniformly compatible and dispersed. Example-1
In the same manner as in the above, toner was obtained using the above mixed resin, and the test results are shown in Table 1.

Example 3 In the same manner as in the preparation of the low molecular weight polymer (a) of Example 1, 100 parts of styrene (St) and 0.4 part of di-tert-butyl peroxide were polymerized to give a polymer having a molecular weight peak of 3,200. A low molecular weight polymer having Mw / Mn of 2.9 was obtained.

The following monomers and initiator were added to the polymerization machine: Styrene (St) 77 parts Butyl acrylate (BA) 18 parts Butyl methacrylate (BMA) 5 parts 1-6 Hexanediol diacrylate 0.12 parts Kayaester HTP 0.24 parts

After mixing and dissolving, gosenol was added.
200 parts of an aqueous solution of deionized water in which 0.57 parts of KH was dissolved was added, and the inside of the polymerization machine was heated to 85 ° C. with stirring to carry out a polymerization reaction for 12 hours. After cooling, dehydration and drying were performed. From the obtained polymer, an insoluble infusible polymer having an insoluble content of 98% in the AFTM test and a leached amount of 0.4 mm was obtained.

Subsequently, the finely pulverized low molecular weight polymer
(a) 62.9 parts, medium-molecular-weight polymer obtained in Production Example-2 (b) 6.1
And 31.0 parts of the insoluble infusible high molecular weight polymer (c) were melt-mixed to obtain a mixed resin which was uniformly compatible and dispersed. Toner was obtained by using the above mixed resin in the same manner as in Example 1, and the test results are shown in Table 1.

Comparative Example 1 36.4 parts of the low molecular weight polymer (a) obtained in the preparation of the low molecular weight polymer of Example 2 and the medium molecular weight polymer (b) 9.
1 part and 54.5 parts of the insoluble infusible high molecular weight polymer (c) obtained in the preparation of the insoluble infusible high molecular weight polymer of Example 1 were melt-mixed, and a mixed resin uniformly mixed and dispersed was obtained. Obtained. Example-1
In the same manner as in the above, toner was obtained by using the above mixed resin, and the test results are shown in Table 2.

Comparative Example 2 In the same manner as in the preparation of the low molecular weight polymer (a) of Example 1, 100 parts of styrene (St) and 0.5 part of di-tert-butyl peroxide were polymerized to give a molecular weight peak of 2,900. A low molecular weight polymer having Mw / Mn of 3.6 was obtained. Also, the high molecular weight polymer of Example-1
In the same manner as in the preparation of (C), a monomer mixture of styrene (St) 75 parts butyl acrylate (BA) 15 parts butyl methacrylate (BMA) 10 parts 1-6 hexanediol diacrylate 0.2 parts was polymerized and AFTM An insoluble and infusible high molecular weight polymer having a test insoluble content of 97% and a leached amount of 0.6 mm was obtained. 87.8 parts of the low molecular weight polymer (a), 4.6 parts of the medium molecular weight polymer (b) obtained in Production Example 1, and the insoluble infusible high molecular weight polymer
(c) 7.6 parts were melt-mixed to obtain a mixed resin which was uniformly compatible and dispersed. A toner was obtained by using the above mixed resin in the same manner as in Example 1, and the test results are shown in Table 2.

Comparative Example 3 100 parts of styrene (St) and 3 parts of di-tert-butyl peroxide were polymerized in the same manner as in the preparation of the low-molecular-weight polymer (a) of Example 1, and the molecular weight was reduced. A low molecular weight polymer having a peak of 1,000 and Mw / Mn of 3.1 was obtained.

80 parts of the above low molecular weight polymer (a) and Comparative Example-2
20 parts of the insoluble infusible high molecular weight polymer (c) obtained by preparing the insoluble infusible polymer was melt-mixed to obtain a mixed resin which was uniformly compatible and dispersed. A toner was obtained by using the above mixed resin in the same manner as in Example 1, and the test results are shown in Table 2.

Comparative Example 4 In the same manner as in the preparation of the low molecular weight polymer (a) of Example 1, 100 parts of styrene (St) and 0.02 part of di-tert-butyl peroxide were polymerized to give a molecular weight of A low molecular weight polymer having a peak of 8,000 and Mw / Mn of 2.8 was obtained.

55.7 parts of the above low molecular weight polymer (a) and Production Example
23.2 parts of the medium molecular weight polymer (b) obtained in Example 3 and Comparative Example 2 above
21.2 parts of the insoluble infusible high molecular weight polymer (c) obtained in the above was melt-mixed to obtain a mixed resin which was uniformly compatible and dispersed. Example-1
In the same manner as in the above, toner was obtained by using the above mixed resin, and the test results are shown in Table 2.

[0101]

Comparative Example -5 6.5 kg of styrene, 3.5 kg of butyl acrylate and 600 g of benzoyl peroxide were charged and mixed and dissolved in a 50 liter polymerization machine, and then polyvinyl alcohol (Gothenol KH) was added.
-17) Add 20 kg of an aqueous solution of 10 g of deionized water,
The inside of the polymerization machine was heated to 140 ° C. with stirring to carry out a polymerization reaction for 10 hours to obtain a polymer having an average molecular weight of 12,000.

In another polymerization machine, 6.5 kg of styrene and 3.5 kg of butyl acrylate were reacted to obtain a polymer having an average molecular weight of 210,000. Further, 6.5 kg of styrene and 3.5 kg of butyl acrylate were reacted in another polymerization machine to obtain a polymer having an average molecular weight of 1,150,000. 60 parts of a polymer having an average molecular weight of 12,000 obtained by the above reaction, 30 parts of a polymer having an average molecular weight of 210,000, and an average molecular weight of 1,1
Using 100 parts of a polymer mixture obtained by mixing 10 parts of a polymer of 50,000, a toner was obtained in the same manner as in Example 1, and the test results are shown in Table 2.

[0103]

Comparative Example -6 8.0 g of styrene, 2.0 g of butyl acrylate, 50 g of divinylbenzene, and 500 g of benzoyl peroxide were charged into a 50-liter polymerization machine and mixed and dissolved. Then, polyvinyl alcohol (Gothenol KH-17) was added. ) 20 kg of an aqueous solution of deionized water in which 10 g was dissolved was added, and the inside of the polymerization machine was heated to 85 ° C with stirring to carry out a reaction for 10 hours to obtain a crosslinked polymer. A toner was obtained using the above crosslinked resin in the same manner as in Example 1, and the test results are shown in Table 2.

[0104]

[Table 1]

[0105]

[Table 2]

[0106]

The present invention relates to a toner for developing an electrostatic image formed in an electrophotographic method, an electrostatic printing method, an electrostatic recording method or the like. The toner obtained in the present invention has excellent non-offset properties, fixing properties, pulverizability during production, blocking resistance during storage (non-aggregation), developability during image formation, and its surface is coated with a resin. In a developer containing a carrier, the charge amount distribution is narrow even when used for a long time while maintaining a high effect of preventing the toner from being spent on the toner, and the generation of the oppositely charged toner, the deterioration of the image quality, and the contamination of the background are prevented. It shows excellent physical properties of no.

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03G 9/08

Claims (4)

(57) [Claims] 1. A toner for developing an electrostatic image comprising a binder resin and a colorant as main components, wherein the binder resin has (a) a GPC molecular weight peak Lp of 1.5 × 10 ³ to less than 4 × 10 ³ . And a low molecular weight polymer of a styrene homopolymer having a weight average molecular weight (Mw) / number average molecular weight (Mn) of less than 4.0 (b) GPC molecular weight peak Mp is 3 × 10 ^{4 to} 5 × 10 ⁵ Styrene-
Medium molecular weight polymer which is a (meth) acrylic acid alkyl ester copolymer (c) Highly insoluble, infusible polymer which is a crosslinked styrene homopolymer or a crosslinked styrene- (meth) acrylic acid alkyl ester copolymer Consisting of a low molecular weight polymer (a) and the insoluble infusible high molecular weight polymer (c), (a) is more than 60 and 80 parts by weight or less, and (c) is 20 Not less than 40 parts by weight and less than 40 parts by weight, and the insoluble infusible high molecular weight polymer (c) is 100 parts by weight of the medium molecular weight polymer (b) is 5 to 60 parts by weight, the binding resin Wherein the THF-insoluble content of the toner is more than 70 and 98% or less. 2. The toner for developing an electrostatic image according to claim 1, wherein the acid value of the binding resin is 0.05 to 2.0 KOH mg / g. 3. The particle size of the insoluble infusible polymer (c) is
The toner for developing an electrostatic image according to claim 1, wherein the toner has a thickness of 0.03 µm to 1 µm. 4. The toner according to claim 1, wherein the low molecular weight polymer (a) is a low molecular weight polymer (a) obtained by bulk polymerization in a system substantially free of a solvent. -.