JPH02187768A - Toner and manufacture of same - Google Patents

Abstract

PURPOSE:To enable amorphous toner particles rugged on the surface to be manufactured and to enhance cleaning performance by adding a substantial amount of fine solid particles specified in diameter at the time of manufacturing a polymer toner by the suspension polymerization method. CONSTITUTION:The amorphous toner having a rugged surface to many protuberances formed on the surface is obtained by adding fine solid particles of 0.5 - 5mum size in an amount of 10 - 100wt.%, preferably, 20 - 60wt.% of the monomer at the time of manufacturing the toner by the suspension polymerization method, and the protuberances of >=0.1mum height have an average frequency of 0.5 - 5mum, and the height and frequency of the protuberances on the surface of the toner can be changed by controlling the kind, particle diameter, and addition amount, thus permitting the obtained amorphous toner to be remarkably enhanced in cleaning performance, as compared with the conventional spherical toner.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an electrophotographic toner using a suspension polymerization method and a method for producing the same.

(Prior art) A method for producing an electrophotographic toner, which involves mixing and dispersing a monomer having an ethylenically unsaturated double bond with a pigment and a charge control agent, and then suspension-polymerizing the dispersion in an aqueous suspension bath. Many patents and miscellaneous papers related to this have been published so far (for example, Japanese Patent Publication No. 55-50964, Japanese Patent Publication No. 55-50883, Japanese Unexamined Patent Publication No. 56-110945, etc.). This is a method of producing desired polymer particles by suspension polymerization using polymers and various inorganic fine powders, and the obtained polymer particles were spherical.

(Problem to be Solved by the Invention) These spherical polymer particles can be classified into a desired particle size and used as an electrophotographic toner, but the spherical toner particles obtained by such a method are sometimes It has been found that the problem of poor cleaning performance occurs when 5,000 to ioooo copies are made. The reason for this is that during the cleaning process of the copying machine, when the remaining toner adhering to the drum is scraped off with a brake V, since the toner is spherical, it rolls and the frictional force is small. It has been found that the particles get stuck between the blade and the photosensitive drum, making it impossible to clean them.

(Means for Solving the Problems) The present inventors focused on this point and, as a result of extensive studies, discovered that by adding an appropriate amount of a certain type of solid fine particles during suspension polymerization, polymerization with an uneven surface can be achieved. They succeeded in producing a toner and found that when these particles were used as a toner, the cleaning performance was significantly improved compared to the case of using a conventional spherical toner, and the present invention was achieved.

That is, in the present invention, when producing a polymerized toner by suspension polymerization, a substantial amount of solid fine particles of 0.5 to 5 μm is added to form an uneven shape based on convex ridges on the toner surface. The present invention relates to an amorphous polymerized toner and a method for producing the same.

The object is a toner in which a large number of solid fine particles with a particle size of 0.5-5 μm adhere to the surface to form convex ridges, and between the convex ridges with a height of 0.1 μm or more. A uniform dispersion of a toner characterized by an average period of 0.5-5 μm, a monomer having an ethylenically unsaturated double bond, a pigment, and an additive is suspended in an aqueous suspension bath. A method for producing a polymerized toner by turbid polymerization, characterized in that a sufficient amount of solid fine particles of 0.5 to 5 μm is present to produce convex ridges on the surface of at least the resulting toner particles. This can be easily achieved by the toner manufacturing method.

The present invention will be explained in detail below.

The polymerized toner of the present invention has a novel shape obtained mainly by using a suspension polymerization method.

That is, it is a toner having convex ridges on the surface formed by a large number of fine solid particles having a particle size of 0.5 to 5 μm, preferably 1 to 5 μm, and having a diameter of 0.1 μm or more. It is a polymerized toner in which the average period of convex ridges with a height of 0.5-5 μm.

Here, solid fine particles are solid fine particles that are newly added in addition to the minimum necessary components for toner obtained by suspension polymerization method, which will be described in detail in explaining the manufacturing method of the present invention. be. In the polymerized toner of the present invention, a large number of such solid particles adhere to the surface and have convex ridges on the surface, and the height of the ridges is 0.1 μm or more, and if it is too low, the uneven surface becomes ineffective. Its height is usually 3μ
Ugly or worse is preferable. Also, the average period of convex ridges is 0.5-
It is in the range of 5μ-. If the cycle exceeds 5 μm, the number of particles fixed on the toner surface will decrease, resulting in a decrease in performance, which is not preferable.

Furthermore, the height of the convex ridges on the surface is the maximum height from the surface assuming that the toner surface is spherical, and the average period is the distance between the vertices between adjacent ridges on the toner surface. Say the average value. Note that these are analyzed based on the shape ascertained by a cross-sectional shape scanning electron microscope, which will be described later.

Next, the manufacturing method of the present invention will be explained.

The monomer having an ethylenically unsaturated double bond used in the present invention is not particularly limited as long as it is used in producing toner, and specifically, styrene monomer, Alternatively, an acrylic acid ester monomer may be used.

Examples of the styrene monomer include styrene, vinyltoluene, ethylstyrene, p-chlorostyrene, p-n butylstyrene, etc., and preferably styrene or vinyltoluene is used.

Examples of acrylic ester monomers include ethyl acrylate, ethyl methacrylate, n-butyl acrylate, n-butyl methacrylate, methyl acrylate, methyl methacrylate, propyl acrylate, propyl methacrylate, etc. Preferably n-butyl acrylate, 11-butyl methacrylate or methyl methacrylate is used. These monomers may be used alone or in combination, and if necessary, cationic monomers such as N,N-dimethylaminoethyl methacrylate, N,N-diethylaminoethyl methacrylate, and vinylibiridine may be used. or unsaturated fatty acids such as acrylic acid, methacrylic acid, maleic acid, heptamalic acid and maleic anhydride, and heptanionic monomers such as unsaturated fatty acid anhydrides.

The pigment is not particularly limited as long as it is used in conventional toners, and specifically, carbon black, iron oxide, zinc oxide, titanium oxide, etc. can be used. It is commonly used in regular toners such as 1-Stone 7Reblack or 7T-Nesblack, and has a particle size of 115-80n.
A moderate amount is sufficient. The amount added may be 1-10% by weight, preferably 3-7% by weight based on the polymerizable monomer; if it is less than 1% by weight, black scale will not be produced sufficiently, and if it exceeds 10% by weight. However, it is not economical because no significant improvement in blackness can be obtained. As additives, charge control agents and waxes are usually used.

The charge control agent may be one that is commonly used, and includes, for example, chlorine, chrome yellow, aniline blue 7, talocyanine blue, and azo alloy dyes.

When using nigrosine as a charge control agent, it is preferable to use a small particle size in order to shorten the dispersion time, and specifically, a particle size of about 3 to 30 μm is advantageous, and the amount added is determined by the amount of the polymerizable monomer. 1-5% by weight, preferably
The content is preferably 2-3% by weight. If it is less than 1% by weight, the toner charge controllability is insufficient and stable images cannot be obtained. Moreover, even if it exceeds 5% by weight, no significant improvement in properties is observed, which is not preferable.

The wax is not particularly limited as long as it imparts releasability to the toner, and includes waxes commonly used in toners, such as polypropylene wax, polyethylene wax, and microcrystalline wax. The amount added is preferably 1-5% by weight, preferably 2-3% by weight based on the polymerized monomer. If it is less than 1% by weight, the mold releasability will be insufficient and offset will easily occur. Moreover, even if it exceeds 5% by weight, the mold releasability is not significantly improved, which is not preferable.

Furthermore, in the present invention, in addition to the above-mentioned components commonly used in toners, solid particles having a particle size of 0.5 to 5 μm, preferably 1 to 5 μm are used to make the surface uneven. The solid fine particles may be inorganic or organic. Examples of inorganic substances include oxides such as iron oxide and titanium oxide. Examples of organic substances include benzoguanamine resin. In this case, it is preferable that the resin does not soften at the polymerization temperature described below. The amount added is at least a sufficient amount to produce convex bumps on the surface of the toner particles obtained, and specifically, it is 10-10,000% by weight or 15-80% by weight based on the polymerizable monomer, and Preferably 20-60% by weight is desirable. By adjusting the type, particle size, and amount of these solid fine particles, the height and period of the convex shapes on the F-toner surface can be adjusted. Although solid fine particles have been added as pigments or antistatic agents in the past, they are not sufficient to produce convex ridges on the surface of the resulting toner particles, and in this respect, the addition of 0.5-5μ A feature of the present invention is that a large amount of solid particles having a specific particle size of - is present.

In the present invention, suspension polymerization is carried out by uniformly dispersing the various components described above. At this time, the crosslinking agent is added at a ratio of 0.1 to the polymerizable monomer so that the polymer has a desired gelation rate. -2% by weight may be added.

As for gelation rate, tetrahydro7 is based on the total amount of resin.
The content of the resin insoluble in the orchid is preferably 50% by weight or less, preferably 45% by weight or less.

If the gelation rate exceeds 50% by weight, the softening point of the resulting toner will become too high and a large amount of thermal energy will be required for fixing the toner when it is used, which is not preferable.

Any commonly used crosslinking agent may be used as such a crosslinking agent, such as compounds having two vinyl groups such as divinylbenzene, divinyl ether, ethylene glycol dimethacrylate, and divinyl ether, each of which may be used alone. It is used in combination with or in combination.

Furthermore, a polymerization initiator is further added to the dispersion of the present invention.

Any commonly used polymerization initiator may be used, such as azobisisobutyronitrile, azobis-2,
4-dimethylvaleroni) +fur, etc. are used.

In the present invention, it is important to uniformly disperse these various components, and in order to prepare such a uniform dispersion, the polymerizable monomers, pigments, and additives are mixed and then heated with an inert gas. under an atmosphere of strong stirrer or disperser, e.g.
Using a homomixer, homogenizer, disperser, etc., at a rotation speed of 4000-10000 rpm, 10-60
This is achieved by intensive dispersion for minutes. The order in which the various components are added when preparing the dispersion is not particularly limited, and may be added all at once or one by one. The temperature during dispersion may be at room temperature, while being slightly heated, or while being cooled, but when heating, only the polymerization initiator should be cooled to below the decomposition temperature after dispersion, and then added again. Dispersion is preferred. Furthermore, if heat is generated during dispersion, it is preferable to disperse while cooling, and in this case as well, it is desirable to add the polymerization initiator just before the dispersion is completed.

The dispersion thus obtained is subjected to suspension polymerization in an aqueous suspension bath. An aqueous suspension bath is usually used for suspension polymerization. Suspension stabilizers such as silica powder, bentonite, calcium phosphate, polyvinyl alcohol, hydroxyethylcellulose, methylhydroxyethylcellulose, gelatin, etc.0.0
01-5 parts by weight were uniformly dispersed in 100 parts by weight of water. Each of these suspension stabilizers can be used alone or as a mixture of two or more kinds. Furthermore, surfactants such as sodium lauryl sulfate, sodium dodecylbenzenesulfonate, etc. can be added to 100 parts by weight of water at o, o o 1
-0.5 parts by weight may be used together.

The amount of bath should preferably be 1 to 10 times the amount of dispersion used. For the formation of suspended particles, a homomixer,
Using a homogenizer or a dispersion machine with strong shearing force such as a disperser, the rotation speed is 4000-10000.
Disperse by rotation for 10-60 minutes. At this time, occasionally observe it with a microscope.
The dispersion time and rotational speed are adjusted so that the number of suspended particles is 100. However, the stirrer or disperser used at that time may be used as is, or the suspension polymerization may be carried out by replacing it with a blade-type or anchor-type stirrer.

The suspended particles thus prepared have an irregular surface shape.

After the polymerization reaction is completed, the toner particles are cooled, filtered, washed, dried, and further classified into desired toner particle sizes to obtain the desired toner particles.

(Effects of the Invention) According to the present invention, amorphous toner particles having an uneven surface can be produced, and the amorphous toner particles have significantly improved cleaning properties compared to spherical toner.

(Examples) The present invention will be specifically explained in Examples below, but the present invention is not limited to the following Examples unless it exceeds the gist thereof.

Example 1 79.5 parts of styrene, 20 parts of 11-butyl 7-acrylate, 0.5 parts of divinylbenzene, 2 parts of polypropylene wax, 2 parts of nigrosine, 5 parts of carbon black, and
10 parts of iron oxide powder (average particle size: 1 μm) was dispersed in a nitrogen atmosphere using a homogenizer at 6500 rpm for 30 minutes.

Next, the degree of saponification was 86, which was 3 times the amount of the obtained dispersion 1.
．． The particles were placed in an aqueous suspension bath containing a 1% aqueous solution of 5% polyvinyl alcohol, and then dispersed in a nitrogen atmosphere using a homogenizer at 5000 rpm for 20 minutes to form suspended particles. Next, the stirrer was replaced with a flat blade stirrer, 3 parts of 2,21-7 zobisisobutyronitrile was added as a polymerization initiator, and the mixture was stirred at 600 rpm under a nitrogen atmosphere at 65°C.
Polymerization was carried out for 3 hours. After cooling, filtering and drying, toner particles of 5-25 μm size were obtained using a classifier.

The surface shape of the toner particles was measured using a cross-sectional scanning electron microscope (hereinafter abbreviated as cross-sectional SEM) (Elionix EM-30).
00) at a magnification of 15,000 times, approximately one-third of the toner surface for multiple toner particles (as a section of the toner surface)
When measured, the average height of convex ridges with a height of 0.1 μm or more was 0.2 μm, and the average period was 1.0 μm.
It was μm.

At this time, the toner was assumed to be a true sphere and the correction was made.

A developer was prepared by mixing these toner particles with iron powder, and it was evaluated using a copying machine using an organic photoconductor (hereinafter abbreviated as OPc) photoreceptor. After 20,000 copies were made, good copied images were obtained. Ta.

Example 2 A toner was polymerized and formed in the same manner as in Example 1 except that the amount of iron oxide powder as an additive was increased from 10 parts to 60 parts, and then the surface shape of the toner particles was measured by cross-sectional SEM. However, the average height of the convex ridges having a height of 0.1 μm or more was 0.2 μm, and the average period was 0.8 μm.

A developer is prepared by mixing these toner particles with iron powder, and OP
When evaluated using a copying machine using a C photoreceptor, good copied images were obtained after 20,000 copies were made.

Example 3 Benzoguanamine resin (average particle size 3 μm) as an additive
The toner was polymerized and formed in the same manner as in Example 1 except that 20 parts of the toner was used.
As measured by M, the average height of the convex ridges with a height of 0.1 μm or more was 0.4 μm, and the average period was 2.4 μm.

A developer is prepared by mixing these toner particles with iron powder, and OP
When evaluated using a copying machine using a C photoreceptor, good copied images were obtained after 20,000 copies were made.

Comparative Example 1 After polymerizing and forming a toner in the same manner as in Example 1 except that 10 parts of iron oxide powder was not included in the composition of Example 1,
When the shape of the surface of the toner particles was measured by cross-sectional SEM, there were no convex protuberances with a height of 0.1 μm or more, and the height of the slight surface irregularities observed was 0.05 μm or less. A developer was prepared by mixing these toner particles with iron powder, and it was evaluated using a copying machine using an OPC photoreceptor.
At the stage of copying 6 sheets, poor cleaning had already occurred and good copied images could not be obtained.

Comparative Example 2 In the composition of Example 1, micro titanium oxide (average particle size 0.05 μv) was used instead of 10 parts of iron oxide powder as an additive.
h) After polymerizing and forming toner in the same manner as in Example 1 except that 40 parts were used, the shape of the surface of the toner particles was determined by cross section S.
As measured by EM, there were no convex protuberances with a height of 0.1 μm or more, and the highest height of surface irregularities observed was 0.05 μm. A developer was prepared by mixing toner particles with iron powder, and when it was evaluated in a copying machine using an OPC photoreceptor, cleaning defects had already occurred after 5-6 copies had been made, and good copied images could not be obtained. Ta.

Claims (2)

[Claims] (1) A toner in which a large number of solid fine particles with a particle size of 0.5 to 5 μm adhere to the surface to form convex ridges, and the height is 0.
．． The average period between the convex ridges of 1 μm to 5 μm is 0.5
- A toner characterized by having a particle size of 5 μm. (2) A method for producing a polymerized toner by suspension polymerizing a homogeneous dispersion of a monomer having an ethylenically unsaturated double bond, a pigment, and an additive in an aqueous suspension bath,
A method for producing a polymerized toner, characterized in that suspension polymerization is carried out in the presence of solid fine particles of 0.5 to 5 μm in an amount sufficient to produce at least convex ridges on the surface of the resulting toner particles.