JPH04184348A - Electrostatic image development toner and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain an image superior in electrification stability and durability and high in resolution by specifying the difference of solubility parameters of a binder resin and a releasing agent to <=0.9, the volume average particle size of the polymerized particle to <=6mum and the diameter B of the releasing agent in the particle against a particle size A of the particle in a specific range. CONSTITUTION:At the toner f polymerized particles in which a styrene-acrylic resin is a binder rein, the difference of solubility parameters of the binder resin and the releasing agent is <=0.9, the volume average particle size of the particle is <=6mum and the domain diameter B of the releasing agent in the particle against the diameter A of the particle is in a range of 0.03<B/A<0.15. As the compatibility of the releasing agent and the binder resin is high, so the releasing agent is dispersed uniformly in the polymerized particles and the electrification stability is obtained. Simultaneously the domain diameter B of the releasing agent is present on the surface of the polymerized particles in a specified range, so that the adhesion of the toner to the photosensitive body is reduced and the durability is also obtained. Also when the releasing agent is taken in a monomer liquid drop during suspension polymerization, the additive incorporated in the liquid drop is not repelled and the toner being superior in the dispersibility of the additive is obtained. As a result, the unevenness of the density is reduced and the image of higher image density is obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electrostatic image developing device used for developing an electrostatic latent image in electrophotography, electrostatic recording, electrostatic printing, etc. This invention relates to toner and its manufacturing method.

[Conventional technology]

In an example of electrophotography, an electrostatic charge image is formed on an image carrier by charging and exposure, this electrostatic charge image is developed with a developer containing toner to form a toner image, and then this toner image is The image is transferred to a transfer material and fixed to form a visible image.

On the other hand, toner remaining on the image carrier without being transferred to the transfer material is preferably cleaned by a cleaning member such as a blade that is placed in pressure contact with the surface of the image carrier.

The toner constituting the developer and its manufacturing method are as follows:
Conventionally, the following techniques have been proposed.

■ JP-A No. 61-62045 proposes a technology in which a binder resin and a mold release agent with a solubility parameter difference of 1.0 or more are combined to produce a mold release effect. has been done.

■ JP-A No. 63-50858 uses two types of polymers A and B with a difference in solubility parameters in the range of 1.0 to 15.0, and as polymer B having the smaller solubility parameter. A technique has been proposed in which fine particles having a volume average particle size of 100 μm or less are used.

■ Unexamined Japanese Patent Publication No. 60-230663 states! ! This is a technology that produces toner with a particle size of 5 to 30 μm through turbidity polymerization, and localizes a mold release agent of a certain size or more to improve mold release properties, resistance to offset/separation, and one-rolling property. Proposed.

(2) Japanese Unexamined Patent Publication No. 60-238844 proposes a technique in which the mold release effect is enhanced by regulating the particle size ratio of polyolefin wax and toner to a range of 0.4 to 2.

■ JP-A No. 62-295073 discloses that the monomer composition obtained by heating the monomer composition above the melting point of the mold release agent and then cooling it below the melting point is granulated in an aqueous dispersion medium. , a technique has been proposed for obtaining a toner having a particle size of 12 μm, in which the releasing agent is uniformly dispersed, and having good fixing properties and anti-offset properties by polymerizing at a temperature below the melting point of the releasing agent. There is.

[Problem to be solved by the invention]

Generally, it is considered effective to form release agent domains with a certain diameter or more in the toner in order to improve the release properties of the toner.

Therefore, as in the above-mentioned known example, a mold release agent having low compatibility with the binder resin is mainly used to form domains of an effective size.

However, when such a mold release agent with low compatibility is used, the dispersibility of additives other than the mold release agent, such as pigments and charge control agents, decreases, which tends to cause concentration unevenness, and reduces charge stability and durability. It also has a negative impact on sexuality.

Furthermore, when a step of precipitating a release agent is included, the solvents that can be used are limited to those with a high boiling point, and therefore, the release agent remains on the surface of the produced toner, which tends to deteriorate the performance of the toner.

Even when this precipitation step is not included, since a release agent of a certain diameter or more that is difficult to dissolve in each other must be included, the toner particle size tends to be large, making it impossible to obtain a toner that can form a high-quality image.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a toner that has excellent charging stability and durability and is capable of forming high-resolution images.

[Means to solve the problem]

The electrostatic image developing toner of the present invention is a styrene-acrylic resin obtained by suspension polymerization using a polymerization composition containing at least a styrene monomer, an acrylic monomer, and a release agent. A toner for electrostatic image development comprising polymer particles having a binder resin, wherein the difference in solubility parameters between the binder resin and the release agent is 0.9 or less, and the volume average particle diameter of the polymer particles is 6 μm or less. It is characterized in that the domain diameter B of the release agent in the polymer particles is in the range of 0.03<B/A<0.15 with respect to the particle size A of the polymer particles.

The method for producing an electrostatic image developing toner of the present invention includes a method for producing a styrene-acrylic toner by a suspension polymerization method using a polymerization composition containing at least a styrene monomer, an acrylic monomer, and a release agent. A method for producing an electrostatic image developing toner comprising polymer particles using a resin as a binder resin, wherein the difference in solubility parameters between the binder resin and the release agent is 0.9 or less, and the volume of the polymer particles is Average particle size is 6μ
m or less, and 0.03 with respect to the domain diameter B of the release agent in the polymer particles or the particle diameter A of the polymer particles.
It is characterized by being in the range of <B/A<0.15.

[Effect]

The high compatibility between the release agent and the binder resin allows the release agent to be uniformly dispersed in the polymer particles, resulting in a uniform surface composition for each toner and improved charging stability. You will get an excellent toner. At the same time, since the release agent has a domain diameter B within a specific range on the surface of the polymer particles, adhesion of toner to the photoreceptor is reduced and durability is also improved.

In addition, because the compatibility between the mold release agent and the binder resin is high, when the mold release agent is incorporated into the monomer droplets during suspension polymerization, the pigments and charge control agents contained in the droplets may be removed. additives are not expelled. Therefore, a toner with excellent dispersibility of additives such as pigments can be obtained. As a result, an image with high image density and less density unevenness can be obtained.

Furthermore, since the monomer and the release agent are compatible, the particle size is less likely to increase, making it possible to efficiently obtain toner with a small particle size of 6 μm or less, which has been difficult to produce in the past.

[Specific explanation of configuration]

Hereinafter, the configuration of the present invention will be specifically explained.

The toner of the present invention is a toner obtained by suspension polymerization, and is composed of polymer particles using a styrene-acrylic resin as a binder resin.

When performing suspension polymerization, a polymerization composition containing at least a styrene monomer, an acrylic monomer, and a mold release agent is used.

Styrene monomers include styrene, 0-methylstyrene, m-methylstyrene, p-methylstyrene, α-
Methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-n-butylstyrene, p-tert
-butylstyrene, p-n-hexylstyrene, p-n
-octylstyrene, p-n-nonylstyrene, p-n
-decylstyrene, p-n-dodecylstyrene, p-methkinstyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene and the like.

Examples of acrylic monomers include methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-octyl acrylate,
Dodecyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, methyl α-chloroacrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n methacrylate α- of butyl, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, etc.
Examples include methylene aliphatic monocarboxylic acid esters, acrylonitrile, methacrylonitrile, acrylic acid or methacrylic acid derivatives such as acrylamide, and the like.

Two or more of the above styrene monomers and acrylic monomers may be used in combination as appropriate.

When carrying out suspension polymerization of the polymerization composition, a common polymerization initiator used in suspension polymerization methods is used.

Specifically, azo initiators such as azobisisobutyronitrile, benzoyl peroxide, methyl ethyl ketone peroxide, isopropyl peroxy carbonate, cumene hydroperoxide, 2,4-dichlorylbenzoyl peroxide, lauroyl peroxide, etc. is selected from the peroxide-based starting side.

As the mold release agent, one whose solubility parameter difference ΔSP with the binder resin is 0.9 or less is used.

Here, the "solubility parameter" is Hi 1debra
It is defined by the following formula in the dissolution theory of nd-Scat-chard.

However, ΔEma represents evaporation energy, V represents molecular volume, and ΔEv/V represents cohesive energy density. The unit of solubility parameter is (cal/cm").

There are various methods for measuring solubility parameters.
r, Eng.

Sci,, 14. (2) 147 (1974)
This value was determined in accordance with the method described in J. In this method, the solubility parameter is calculated from the data of the evaporation energy and molar volume of atoms and atomic groups using the following formula in the structural formula of the object to be measured.

Furthermore, Δel and ΔV each represent the evaporation energy per volume of an atom or an atomic group.

If a release agent with a solubility parameter difference ΔSP of more than 0.9 with the binder resin is used, the compatibility between the two will be low, resulting in poor dispersibility of additives such as pigments and charge control agents. As a result, the charging stability and durability of the toner decrease.

Specific examples of such mold release agents include fatty acid ester waxes such as carnauba wax and montan wax, fatty acid amide waxes such as capric acid amide and stearic acid amide, and bisamide waxes.

The polymerization composition may contain other additives as necessary. Examples of such additives include coloring agents, charge-control fittings, and the like.

Various dyes and pigments are used as colorants, specifically carbon black, nigrosine dye, aniline blue, calco oil blue, chrome yellow, ultramarine blue, DuPont oil red, orient oil red #330, quinoline. Yellow, methylene blue chloride, phthalocyanine blue, malachite green offsalate, lamp black, rose bengal, oil black, azo oil black, etc. are used.

As the charge control agent, a conventional charge control agent can be used.

During suspension polymerization, a suspension stabilizer may be used to prevent the dispersed particles from coalescing. Such suspension stabilizers include water-soluble polymer substances such as gelatin, starch, and polyvinyl alcohol, poorly water-soluble salts such as barium sulfate, calcium sulfate, barium carbonate, calcium carbonate, and calcium phosphate, and these poorly water-soluble salts. Examples include combinations with surfactants such as sodium dodecylbenzenesulfonate and sodium dodecyl sulfate, inorganic polymeric substances such as talc, clay, silicic acid, and diatomaceous earth, and poorly water-soluble inorganic compounds such as metal oxides.

The polymer particles constituting the toner of the present invention have a volume average particle diameter of 6 μm or less. With such small-diameter polymer particles, images with high resolution can be obtained. However, when the volume average particle diameter exceeds 6 μm, the resolution decreases.

Here, the "volume average particle diameter" of the polymer particles is "Coulter
Counter” (aperture 100μm.

(manufactured by Coulter Electronics).

Furthermore, the polymer particles constituting the toner of the present invention have a domain diameter B of the release agent in the polymer particles or a particle size A of the polymer particles in the range of 0, oa < B/A < 0.15. It is something that is in . When the domain diameter B of the release agent is within such a range, a toner can be obtained that has excellent low-temperature fixing properties and offset resistance, as well as excellent filming resistance on photoreceptors and the like. However, when the ratio B/A is less than 0.03, low-temperature fixing properties and offset resistance decrease, and conversely,
．． When it is 15 or more, it is easy to film on the photoconductor, etc.
Durability decreases.

Here, the "domain diameter B" of the mold release agent was measured as follows.

Photograph the cross section of the polymer particles using a transmission electron microscope (TEM), and based on the photograph, measure the major axis of the domain of the release agent and the longest axis (minor axis) in the direction orthogonal to it. The average value was taken as the domain diameter of the mold release agent. This measurement was performed for about 100 domains of the mold release agent, and the average value thereof was taken as the domain diameter B of the mold release agent.

Next, a case in which the toner of the present invention is manufactured by applying the suspension polymerization method will be specifically described.

Thoroughly mix a polymerization composition containing at least a styrene monomer, an acrylic monomer, a mold release agent, and a polymerization initiator, coloring agent, etc. added as necessary using a Santo Starr, etc. do. This polymerization composition is added to a dispersion medium containing a suspension stabilizer added as necessary, and this is suspended and dispersed using a high-speed stirrer such as a homogenizer, and maintained at a predetermined temperature condition to undergo a polymerization reaction. I do.

The particle size of the polymer particles thus obtained can be adjusted by adjusting the suspension and dispersion state of the polymerization composition. By adjusting the dispersion conditions, polymer particles having a volume average particle diameter of 6 μm or less can be easily obtained.

In the present invention, the toner may be composed only of the polymer particles obtained as described above, but the toner may also be composed by adding and mixing a fluidizing agent to the polymer particles from the outside.

Such fluidizing agents include silica, aluminum oxide,
Examples include fine particles such as titanium oxide.

〔Example〕

Hereinafter, the present invention will be described in detail, but the embodiments of the present invention are not limited to these Examples. In addition, in the following, "part" represents "part by weight".

<Example 1> 85 parts of styrene, 15 parts of butyl acrylate, 10 parts of carbon black, 0.2 parts of 2,2'-azobisisobutyronitrile (polymerization initiator), carnauba wax (mold release A composition for polymerization is prepared by mixing and dispersing 10 parts of a colloid containing 3% by weight of calcium phosphate and 0.03% by weight of sodium dodecylbenzenesulfonate in a stainless steel beaker with a capacity of 1 liter. In addition to the aqueous solution, a high-pressure homogenizer is used to
The mixture was stirred at a stirring speed of 00 rpm.

Thereafter, the temperature was raised to 80° C., and the polymerization reaction was continued for 8 hours while stirring at a stirring speed of 500 rpm using a conventional stirrer to complete the polymerization. After the polymerization was completed, the solid matter was filtered off and dried to obtain a toner made of polymerized particles.

<Example 2> Example 1 except that 10 parts of stearamide (mold release agent) was used instead of carnauba wax.
A toner was obtained in the same manner.

Comparative example! > 85 parts of styrene, 15 parts of (n)butyl methacrylate, 0.4 parts of ethylene glycol dimethacrylate, 197,210 parts of carbon, 3 parts of 2,2'-azobis(2,2°-dimethylvaleronitrile) Polypropylene, which had previously been ground in methanol with a sand stirrer, was added to the mixture and dispersed with a sand stirrer, and the polypropylene was uniformly dispersed to obtain a polymerization composition.

Add this to 20% by weight of water containing 1% by weight of calcium phosphate and 0.01% by weight of sodium dodecylbenzenesulfonate, and disperse using a regular TK homojetter so that the particle size is 7 to 15 μm. A suspension was obtained.

This suspension was heated at 60°C for 20 hours to polymerize, then treated with hydrochloric acid, the solid content was filtered, washed, and dried.
A toner consisting of polymer particles was obtained.

Comparative Example 2 A toner was obtained in the same manner as in Example 1 except that carnauba wax (release agent) was not used.

For each toner obtained in the above Examples and Comparative Examples, the difference ΔS in the solubility parameters of the binder resin and the release agent
P, the volume average particle size and particle size range of the polymer particles, the ratio B/A of the domain diameter B of the mold release agent to the particle size A of the polymer particles;
The values are shown in Table 1.

However, the spread of particle size was evaluated by measuring the number average molecular weight M1 and the volume average molecular weight M, and by the value of the ratio M, /M1. The closer to a single variance, the closer the value of this ratio is to 1 (.

A spherical carrier 9 coated with 4 parts of each of the above toners and a styrene-methyl methacrylate copolymer (composition ratio 3)
6 parts to prepare a developer, and this developer is used in an electrophotographic copying machine [Konica U-Bix 3042J (
A live-action test was conducted using Konica (side part), and the following evaluations were made.

Charging Stability〉 Actual copying in which copied images are formed 10,000 times using each developer under high-temperature environmental conditions of 30°C and 80% relative humidity, with a 5-hour pause after every 5,000 copies. We conducted a test and measured the toner charge amount at the start and at the end of 10,000 copies using the blow-off method.
The difference is displayed. - For boat fishing, if the difference is 5 μC/g or less, the charging stability is considered to be good, and if the difference is 15 μC/g or more, the charging stability is considered to be poor.

Resolution> 1m as a blade in accordance with JIS Z4916
Horizontal lines equally spaced per m, 4.0, 5.0, 6.3
Using a chart provided with 8.0 lines, the resolution was determined by the blades in which horizontal lines could be discerned, and measurements were taken at the start and end of 10,000 live-action tests.

<Minimum fixing temperature and offset occurrence temperature> By forming an unfixed image using the above electrophotographic copying machine and fixing it by changing the fixing temperature using a separately prepared fixing tester,
For each toner, the minimum fixing temperature and the minimum temperature at which an offset phenomenon occurs (offset occurrence temperature) were determined.

However, the "minimum fixing temperature"
This is the lowest temperature at which stains do not occur when rubbed with the K wiper, and the "offset generation temperature" is the lowest temperature at which stains occur on subsequent paper supplied to the fixing device.

Maximum image density> Indicated by the relative density of the developed image when the image density of the original image is 1.3. Measurement is done with "Sakura densitometer"
(manufactured by Konica).

The above results are shown in Table 2.

As is clear from Table 2, the toner of the present invention has a low minimum fixing temperature, a high offset generation temperature, a wide fixable temperature range, a high maximum image density, and excellent resolution.

〔Effect of the invention〕

The electrostatic image developing toner of the present invention has excellent charging stability and durability, and can provide images with high resolution.

Further, according to the method for producing a toner for developing an electrostatic image of the present invention, a toner having the above-mentioned excellent properties can be reliably produced.

Claims (1)

[Scope of Claims] (1) A styrene-acrylic resin obtained by suspension polymerization using a polymerization composition containing at least a styrene monomer, an acrylic monomer, and a mold release agent is used as a binder. An electrostatic image developing toner comprising polymer particles as a resin, wherein the difference in solubility parameters between the binder resin and the release agent is 0.9 or less, and the volume average particle diameter of the polymer particles is 6 μm or less. An electrostatic image characterized in that the domain diameter B of the release agent in the polymer particles is in the range of 0.03<B/A<0.15 with respect to the particle size A of the polymer particles. Toner for development. (2) A static polymeric particle consisting of polymer particles using a styrene-acrylic resin as a binder resin is produced by a suspension polymerization method using a polymerization composition containing at least a styrene monomer, an acrylic monomer, and a mold release agent. A method for producing a toner for electrophotographic development, wherein the difference in solubility parameters between the binder resin and the release agent is 0.9 or less, the volume average particle diameter of the polymer particles is 6 μm or less, and the polymerization An electrostatic image developing toner characterized in that the domain diameter B of the release agent in the particles is in the range of 0.03<B/A<0.15 with respect to the particle diameter A of the polymer particles. Production method.