JPH037954A - Manufacture of polymer toner and polymer toner - Google Patents

Abstract

PURPOSE:To enhance humidity resistance, fluidity, storage stability by suspension polymerizing a monomer composition containing a polymerizable monomer and a colorant and then processing it with tetraalkyl-o-titanate. CONSTITUTION:The polymer toner is obtained by suspension polymerizing the monomer composition containing the polymerizable monomer and the colorant, filtering the suspension liquid, washing the filter cake with water or the like, adding an organic solvent, again filtering it to substitute the solvent for the water, adding the tetraalkyl-o-titanate represented by Ti(OR)4, R being a monovalent 1 - 10C hydrocarbon group optionally same or different, further subjecting them to filtration or centrifugal filtration treatment or the like to easily react the Ti(OR)4 with the part of the hydrophilic group on the surface of each polymer toner particle and to execute surface treatment of the polymer toner, thus permitting humidity resistance, fluidity, storage stability, and the like to be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing a polymerized toner having excellent moisture resistance, storage stability, and triboelectric chargeability.

[Conventional technology]

Conventionally, toner used for electrophotography, etc. is generally made by kneading additives such as colorants such as carbon blank and charge control agents in thermoplastic resin, uniformly dispersing the resin, and then pulverizing it with a pulverizer and then passing it through a classifier. It is manufactured using the so-called pulverization method, in which the toner is classified into particle sizes suitable for toner. Toner produced by this pulverization method has several problems.

In other words, in the toner manufactured using this pulverization method, the material must be brittle to some extent so that it can be easily pulverized. However, if a material that is too brittle is used, the toner may become too finely powdered. , in order to finally obtain a toner with an appropriate particle size distribution, fine powder must be removed, which increases the manufacturing cost.
Furthermore, such toner may be further pulverized in the developing device of a copying machine during the process of continuous copying. Also,
If a low-melting point material or a pressure-fixable material is used for the toner to improve heat fixability, the toner may fuse in the crusher or classifier, making continuous production impossible. arise.

In order to solve the problems of the pulverization method, it has been proposed to produce polymerized toner from polymerizable monomers by a suspension polymerization method (Japanese Patent Publication No. 14895/1989, Japanese Patent Publication No. 51-14895,
7-53756 etc.).

When a developing toner is obtained by a conventional general suspension polymerization method, a monomer composition containing at least a colorant consisting of a polymerizable monomer and a carbon blank is mixed with a suspension stabilizer. It is granulated to the particle size of the toner using an appropriate stirrer in an aqueous medium etc., and the radicals generated when the polymerization initiator added in advance or the newly added polymerization initiator is decomposed by heat. , a polymerizable monomer is polymerized to form a polymer to produce a polymerized toner. In other words, since this suspension polymerization method does not include a pulverization process, there is no need to select brittle materials for the polymerized toner, and since the polymerized toner has a spherical shape, the polymerized toner has excellent fluidity and triboelectric charging properties. It has characteristics such as being uniform. However, since polymerized toner is manufactured in an aqueous medium containing a suspension stabilizer, after suspension polymerization,
A washing step is required to remove suspension stabilizers and the like.

The washing process is usually carried out using a solvent that dissolves the suspension stabilizer, such as water, but since the particle size of the polymerized toner is small at 10 μm or less, methods such as filtration and centrifugation are difficult to operate, and from a cost standpoint. It is also difficult to perform the cleaning process sufficiently.

That is, after the completion of polymerization, excess suspension stabilizer present in the aqueous phase can be easily removed by washing with a solvent such as water, but Q33 that coats the surface of the polymer particles
Stabilizers are very difficult to remove due to their strong affinity with particle surfaces. Further, since some of the suspension stabilizer molecules may be embedded in the particles and physically fixed to the particle surface, it is considered nearly impossible to remove such suspension stabilizers by washing.

If these suspension stabilizers remain attached to the surface of the polymerized toner particles, the hydrophilic group portions of the suspension stabilizers in particular absorb moisture in the air, which may affect the moisture resistance and fluidity of the polymerized toner. , storage stability, etc. are significantly deteriorated, and other physical properties of the toner, such as triboelectric charging properties, development characteristics, and durability, are also adversely affected.

[Problem to be solved by the invention]

An object of the present invention is to provide a method for producing a polymerized toner and a polymerized toner that solves the above-mentioned problems.

Another object of the present invention is to improve moisture resistance, fluidity, storage stability, triboelectric chargeability, etc. by treating the surface of polymerized toner particles to which suspension stabilizers and the like remain attached with a tetraalkyl orthotitanate. The object of the present invention is to provide a polymerized toner with good development characteristics, durability, etc., and to provide a method for producing the same.

[Means to solve the problem]

In order to solve the problems faced by the conventional techniques, the present inventors, as a result of intensive research, carried out suspension polymerization of a monomer composition containing at least a polymerizable monomer and a colorant. By treating the surface of polymerized toner particles to which the stabilizer remains attached with a tetraalkyl orthotitanate, moisture resistance, fluidity, storage stability, etc. are improved, and it has been found that this is extremely effective in achieving the above objectives. It started. That is, in the present invention, a polymerized toner is produced by suspension polymerizing a monomer composition containing at least a polymerizable monomer and a colorant, and after the polymerization is completed, the toner is treated with a tetraalkylorthotitanate ester. The present invention relates to a method for producing a polymerized toner characterized by the above features, and a toner obtained in this manner.

The surface-treated polymerized toner obtained in the present invention is preferably surface-treated by the following method, but is not limited to the following method.

After the suspension polymerization is completed, the suspension is filtered and washed briefly with water to obtain a slurry of polymerized toner. An organic solvent such as ethanol is added to this and filtered again to replace the water and organic solvent.

By adding tetraalkyl orthotitanate to this and further processing using filtration or a centrifugal filter, the tetraalkyl orthotitanate easily reacts with the hydrophilic group on the surface of the polymerized toner particles. , a surface-treated polymerized toner is obtained.

Alternatively, the same treatment as above may be performed by adding a tetraalkyl orthotitanate ester to an organic solvent such as ethanol in advance, and then substituting it with water.

Further, in order to improve the hydrophobicity of the surface of the polymerized toner, an organic solvent or the like that can swell the particles may be used in combination.

Generally, the reactivity of a chemical reaction increases as the temperature increases, so heating increases the reaction rate and the hydrolysis reaction progresses in a short time, so the treatment time can be shortened.

Furthermore, after the above treatment, it is more preferable to remove the free tetraalkyl orthotitanate by washing with an organic solvent such as ethanol.

In addition, as another treatment method, after the suspension polymerization is completed, the suspension is filtered, washed simply with water, etc., and dried to obtain an untreated polymerized toner. By spraying a solution of a suitable amount of tetraalkyl orthotitanate dissolved in a solvent onto the untreated polymerized toner and stirring and mixing, the tetraalkyl orthotitanate easily interacts with the hydrophilic group on the surface of the polymerized toner particles. Through the reaction, a surface-treated polymerized toner can be obtained.

The tetraalkyl orthotitanate used in the present invention is represented by -maximum Ti(OR)4 and has at least one titanium atom in the center, and in this titanium atom,
It has four hydrolyzable functional groups that can react with the hydrophilic group site on the surface of the polymerized toner particles.

This organic titanate ester absorbs moisture from the atmosphere at or near room temperature and undergoes hydrolysis and polycondensation reactions, forming a titanium oxide film.

Therefore, the polymerized toner is provided with a particle surface having excellent moisture resistance, storage stability, and triboelectric chargeability.

On the other hand, organic titanium compounds have the general formula (R' 0), %
There is a titanate coupling agent represented by Ti(OR')a--. Here, R'0 is a hydrolyzable alkoxy group having 1 to 10 carbon atoms, R# is a lipophilic monovalent hydrocarbon functional group such as a stearyl group having 10 or more carbon atoms, and n is 1 or an integer of 2 or 3. This titanate coupling agent has both a hydrolyzable functional group and a non-hydrolyzable organophilic functional group, so it is effectively used in compounds that connect inorganic and organic materials, but it is difficult to use for polymerization after suspension polymerization. When the toner particle surface is treated with the titanate coupling agent, the surface of the polymerized toner is coated with lipophilic properties, resulting in poor storage stability, moisture resistance, and triboelectric charging properties, and therefore, the use of the titanate coupling agent is not appropriate.

That is, the toner obtained in the present invention is made of, for example, Ti(OR3
) When treated with (a), the following results, and the toner particles are coated with a strong titanium oxide film in the form of a wire having a portion chemically bonded to the surface of the toner particles, exhibiting favorable characteristics.

Surface hydrophilic group Hydrophilic group and chemical reaction 0 -Ti-0-Ti -0 00 0Ti-0-Ti-0 Toner surface In contrast, for example, a titanate coupling agent (R1: hydrolyzed easy functional group,
When R2: an organophilic functional group that does not hydrolyze) is used, the structure is such that an inorganic substance and an organic substance are connected by a coupling agent, so there is no film formation by titanium oxide, and the effects as in the present invention are not exhibited.

As the tetraalkyl orthotitanate used in the present invention, commercially available ones can be used as they are, and specifically, for example, tetramethoxytitanium, tetraethoxytitanium, jetoxydiisopropoxytitanium, dimethoxydiisopropoxytitanium, Butoxytitanium, tetraisopropoxytitanium, tetra-n-butoxytitanium, tetra(
Titanium having the same or different alkoxy group, such as 2-ethylhexoxy) titanium, is preferably used.

The amount of tetraalkyl orthotitanate added to the polymerized toner varies depending on the particle size of the polymerized toner, the type of surface hydrophilic group, the content, etc.
0.05 to 10 parts by weight, preferably 0.1 parts by weight
~3 parts by weight.

If the amount of the organic titanium compound added is less than 0.05 parts by weight, it is not sufficient to deactivate the hydrophilic group portion of the suspension stabilizer that remains attached to the particle surface, and if it exceeds 10 parts by weight, the suspension stabilizer This means that there are many free organic titanium compounds that do not bond to the hydrophilic group sites of .

Next, the suspension stabilizer used in the present invention will be explained.

Suspension stabilizers generally used in suspension polymerization are often surfactants having a hydrophilic group and a hydrophobic group in their molecules. Suspension stabilizers are composed of polar groups such as hydroxyl groups, carboxyl groups and their salts, sulfonic groups and their salts as hydrophilic groups, and nonpolar groups such as aliphatic and aromatic groups as hydrophobic groups, It is a compound that has the ability to prevent coalescence and stabilize the monomer composition particles formed by the granulation process.

Such Qi stabilizers include polyvinyl alcohol, casein, gelatin, cellulose derivatives such as methyl cellulose, methyl hydroxypropyl cellulose, and ethyl cellulose, starch and its derivatives, poly(meth)acrylic acid and its salts, polystyrene sulfonic acid and their salts. These suspension stabilizers coat the surface of the droplets during polymerization and function to prevent coalescence and agglomeration of the droplets.

As the suspension stabilizer used in the present invention, a suspension stabilizer having a carboxyl group, a hydroxyl group, etc. that has relatively high reactivity with an organic titanium compound is preferably used.

Next, materials constituting the monomer composition for producing the polymerized toner of the present invention other than those mentioned above will be explained.

Polymerizable monomer: As the main component of the monomer composition used in the polymerized toner of the present invention, for example, the following polymerizable monomers can be used.

Examples of such polymerizable monomers include styrene, O
-Methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p
-ethylstyrene, 2,4-dimethylstyrene, p-n
-butylstyrene, p-tert-butylstyrene, p
-n-hexylstyrene, p-n-octylstyrene,
Styrene and its derivatives such as p-n-nonylstyrene and p-n-decylstyrene, ethylenically unsaturated monoolefins such as ethylene, propylene, butylene and isobutylene, vinyl chloride, hnylidene chloride, vinyl bromide, vinyl fluoride, etc. /% Logenyl vinyl esters Organic acid vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate, methacrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, methacrylate n
- Methacrylic acid and its derivatives such as butyl, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, acrylic acid, acrylic acid Methyl, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, etc. acrylic acid and its derivatives, vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether, vinyl methyl ketone, vinyl hexyl ketone,
Vinyl ketones such as vinyl isopropenyl ketone, N-
Examples include N-vinyl compounds such as vinylpyrrole, N-vinylcarbazole, N-vinylindole, and N-vinylpyrrolidone, and polymerizable monomers such as vinylnaphthalenes, acrylonitrile, methacrylonitrile, and acrylamide.

These monomers may be used alone or in combination of two or more in various compositions as required.

Among the above seven monomers, it is preferable to use styrene or a styrene derivative alone or in combination with other monomers as a polymerizable monomer in order to improve the development characteristics and durability of the toner.

Next, the coloring agent constituting the present invention will be explained.

Carbon black is suitable as the colorant in the present invention.

That is, the carbon black used in the present invention can be used without any restrictions on number average particle size, oil absorption, pl+, etc., and commercially available products include the following.

For example, RIEGAL manufactured by Cabot, USA
400.660.330.300.5RF-5, STERLING So, ■, N5SR, Columbia Carbon Japan-made 't-hair (RAVEN)
H2OSMT-P.

410, 420.430.450.500.760
, 780.

1000.1035.1060.1080, Mitsubishi Chemical Corporation 1110B, 115B, #40.12400
BSMA-100, etc. These carbon blacks may be used alone or in combination of two or more in various compositions.

As the colorant other than carbon black, a colorant that can be dispersed in the monomer composition and exhibits a clear color and excellent stability over time when used as a toner is used.

Examples of such colorants include phthalocyanine pigments, rhodamine lake pigments, azo lake pigments, iron oxide, titanium oxide, alumina, barium sulfate, and the like.

The amount of the colorant added is 1 to 40 parts by weight, preferably 5 to 20 parts by weight, based on 100 parts by weight of the polymerizable monomer.

In addition, in the present invention, in order to improve heat fixability and offset resistance, waxes such as paraffin wax,
Low softening point compounds having mold release properties, such as low molecular weight polyolefins such as low molecular weight polyethylene and low molecular weight polypropylene, may be added to the monomer composition.

Furthermore, in the present invention, a crosslinking agent may be added and suspension polymerization may be carried out in order to improve blocking resistance and durability. As such a crosslinking agent, a known crosslinking agent such as divinylbenzene can be added to the monomer composition.

Furthermore, in the present invention, a known charge control agent may be added to the monomer composition if necessary. Such charge control agents include metal complexes of organic compounds having carboxyl group ζ sulfonic acid esters or nitrogen-containing groups, metal-containing dyes, and the like.

The polymerization initiator used in the present invention is preferably soluble in the polymerizable monomer.

Such polymerization initiators include 2,2'-azobisisobutyronitrile, 2,2'-azobis-(2,4-dimethylvaleronitrile), 2,2'-azobis-4-methoxy-2, Examples include 4-dimethylvaleronitrile and other azo or diazo polymerization initiators; benzoyl peroxide, methyl ethyl ketone peroxide, isopropyl peroxy carbonate, and other peroxide polymerization initiators.

However, benzoyl peroxide-based polymerization initiators decompose and produce carboxylic acids such as benzoic acid as by-products, which may have an adverse effect on toner storage stability, and may also produce aromatic odors. Since there are drawbacks, it is preferable to use an azo polymerization initiator.

In the present invention, it is preferable to use two or more of the above polymerization initiators in combination in various compositions for the purpose of controlling the molecular weight and molecular weight distribution or for the purpose of controlling the reaction time. Furthermore, a water-soluble initiator such as ammonium persulfate or potassium persulfate may be used in combination, if necessary.

The amount of the polymerization initiator used is usually 0.1 to 20 parts by weight, preferably 1 to 10 parts by weight, per 100 parts by weight of the polymerizable monomer. If the amount of the polymerization initiator is less than 0.1 part by weight, the degree of polymerization of the polymer composition will become too high and the polymerization time will become long, which is not preferable.

On the other hand, if the polymerization initiator exceeds 20 parts by weight, the molecular weight of the polymerization product becomes too low, which is not preferable.

In the present invention, the suspension polymerization reaction is usually carried out at a polymerization temperature of 5
The temperature is set at 0° C. or higher, taking into consideration the decomposition temperature of the polymerization initiator. If the set temperature is too high, the polymerization initiator will rapidly decompose, which will affect the molecular weight, etc., which is not preferable.

Further, a neutral salt such as sodium chloride or sodium sulfate may be added to the continuous phase (aqueous phase) for the purpose of preventing emulsification. Also,
Furthermore, a thickener such as glycerin or ethylene glycol may be added for the purpose of preventing coalescence of the monomer composition particles formed in the granulation process.

〔Example〕

Hereinafter, the present invention will be specifically explained based on Examples.

<Example 1> 90 g of styrene, 10 g of n-butyl acrylate, and 20 g of carbon black (manufactured by Mitsubishi Kasei Corporation, 1140) were placed in a separable flask, and after purging with nitrogen gas for about 30 minutes, the carbon black was heated to 100°C or higher. The surface was treated with a polymerizable monomer to obtain surface-treated carbon black.

After mixing and dispersing the surface-treated carbon black obtained above using a paint conditioner at room temperature for about 1 hour, 5 g of 2,2'-azobisisobutyronitrile was added and dissolved. A monomer composition was prepared.

Next, a polyacrylic acid aqueous solution (manufactured by Wako Pure Chemical Industries, Ltd., approximately 25%
, 8,000-12,000 c P) and 4 g of sodium sulfate were dissolved in 500 g of distilled water to a volume of ff.
Add the above-prepared monomer composition to a 1 liter separable flask, and mix at 60°C with a TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) at 10,000 rpm for approx.
After that, the temperature was 60°C using a turbine with a flat plate.
, for 6 hours, and then at 80° C. for 1 hour.

The polymer composition obtained above was cooled and filtered, and then thoroughly washed with water until the washing liquid became neutral, and then ethanol was added to replace the water and ethanol to obtain a slurry of polymerized toner.

The surface of the polymerized toner was treated by adding 2 g of tetra-n-butoxytitanium to the slurry of the polymerized toner and stirring. After the treatment, free organic titanium compounds were washed away with ethanol and dried to obtain the polymerized toner of the present invention.

When the particle size of the obtained polymerized toner was measured using a Coulter counter (aperture 100 μm), the volume average particle size of the toner was 8.2 μm.

When this polymerized toner was observed under an optical microscope (magnification: 450 times), each particle of the toner had a completely black spherical shape, and no uneven distribution of carbon black was observed within the toner particles. Further, the fluidity of this polymerized toner was superior to that of the polymerized toner obtained in the comparative example.

Furthermore, using this toner, a commercially available copying machine (manufactured by Sharp Corporation, 5P-8260) was used at a room temperature of 30°C and a humidity of 80% RH.
When an image formation test was conducted under these conditions, images with good density and image quality were obtained.

<Example 2> After the above monomer mixture was mixed and dispersed at room temperature for about 1 hour using a paint conditioner, 5 g of 2.2''-azobisisobutyronitrile was added and dissolved to obtain the monomer composition. Adjusted things.

A polymerized toner slurry was obtained from the monomer composition in the same manner as in Example 1.

The surface of the polymerized toner was treated by adding 2 g of tetraisopropoxy titanium to the polymerized toner slurry and stirring. After the treatment, free organic titanium compounds were washed away with ethanol and dried to obtain the polymerized toner of the present invention.

When the particle size of the obtained polymerized toner was measured using a Coulter counter (aperture 100 μm), the volume average particle size of the toner was 8.5 μm.

When this polymerized toner was observed under an optical microscope (magnification: 450 times), each particle of the toner had a spherical shape, and the phthalocyanine pigment within the toner particles was uniformly dispersed, with no uneven distribution observed. Further, the fluidity of this polymerized toner was superior to that of the polymerized toner obtained in the comparative example.

Furthermore, using this toner, a commercially available copying machine (manufactured by Sharp Corporation, 5F-8260) was used at a room temperature of 30°C and a humidity of 80% RH.
When an image formation test was conducted under these conditions, images with good density and image quality were obtained.

<Comparative Example> A polymerized toner was obtained by performing suspension polymerization in the same manner as in Example I, except that the slurry of the polymerized toner was not treated with tetraisopropoxy titanium.

The particle size of the obtained polymerized toner was measured using a Coulter counter (Aperture 10100II), and the volume average particle size of the toner was 8.2 μm.

When this polymerized toner was observed under an optical microscope (450x magnification), each particle of the toner was almost completely black and spherical, and no uneven distribution of carbon black was observed within the toner particles. (Manufactured by Sharp Corporation,
5F-8260) at a room temperature of 30°C and a humidity of 80% R) I
When an image formation test was conducted under the following conditions, it was found that the density and image quality decreased as the number of copies increased.

〔Effect of the invention〕

Since the polymerized toner of the present invention is treated with a tetraalkyl orthotitanate after polymerization, it has excellent fluidity, exhibits uniform triboelectric charging properties, and can provide stable images with high image density. Furthermore, since the hydrophilic group sites on the particle surface are deactivated, a toner with improved storage stability and offset resistance can be obtained.

Claims (1)

[Claims] 1) A polymerized toner is produced by suspension polymerizing a monomer composition containing at least a polymerizable monomer and a colorant, and after the polymerization is completed, a polymerized toner of the general formula Ti(OR)_4 is produced. (Here, R has 1 to 10 carbon atoms.
represents different or similar monovalent hydrocarbon groups. ) A method for producing a polymerized toner, comprising treating it with a tetraalkyl orthotitanate represented by: 2) The method for producing a polymerized toner according to claim 1, characterized in that the amount of the tetraalkyl orthotitanate added to 100 parts by weight of the polymerized toner is 0.05 to 10 parts by weight. 3) A polymerized toner characterized in that the surface of polymerized toner particles produced by a suspension polymerization method is coated with a reticulated titanium oxide film having a portion chemically bonded to the surface of the toner particles.