JPH0153788B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a toner for developing electrostatic images, and more specifically, the present invention relates to a method for producing a toner for developing electrostatic images, and more particularly, the present invention relates to a method for producing a toner for developing electrostatic images, and more particularly, the present invention relates to a method for producing a toner for developing an electrostatic image. The present invention relates to a method for producing a toner for developing electrostatic images, characterized in that a polymer obtained by suspension polymerization in a medium is treated with a silane coupling agent or a titanate coupling agent.

Conventional toners generally contain colorants and thermoplastic resins.
After melt-mixing and uniformly dispersing other additives,
Toner having a desired particle size has been manufactured using a pulverizer and a classifier. Although this manufacturing method can produce fairly good toners, it does have certain limitations.
That is, the toner obtained using the pulverization method must have some brittleness so that the material is somewhat susceptible to pulverization. However, if the toner is too brittle, it will be pulverized too much, and in order to obtain a toner with an appropriate particle size distribution, it will be necessary to cut the toner into fine powder which is not economical, which will increase the cost. Furthermore, in some cases, the toner is further pulverized in the developing device of a copying machine.
In addition, if a low melting point material or a pressure fixing material is used to improve heat fixing properties, a crushing device,
Alternatively, a fusion phenomenon may occur in the classification device, and continuous production may not be possible.

Other requirements for the toner are that it has triboelectric properties suitable for development, that it forms an excellent image;
The characteristics include no change in performance when left standing, no solidification (blocking, etc.), appropriate heat or pressure fixing properties, and no contamination of the surface of the photoreceptor.

In order to overcome the drawbacks of the pulverization method, a method for producing toner using a suspension polymerization method was proposed. That is, since this method does not involve any pulverization process, brittleness is not required, and the spherical shape provides excellent fluidity, resulting in uniform triboelectrification. Furthermore, by appropriately controlling polymerization, using a crosslinking agent, or incorporating some kind of additive, a toner with excellent heat or pressure fixing properties can be obtained. However, it is necessary to carry out the polymerization in a stable suspension system without coalescence, and
It is technically difficult to obtain fine polymer particles with a uniform particle size distribution by polymerization. Therefore, when suspension polymerizing a polymerizable monomer system in water, a suspension stabilizer is used to prevent coalescence of polymer particles as the polymerization progresses.

Generally, suspension stabilizers include poorly soluble finely powdered inorganic compounds such as BaSO ₄ , CaSO ₄ , MgCO ₃ ,
Slightly soluble salts such as BaCO ₃ , CaCO ₃ , Ca ₃ (PO ₄ ) ₂ , inorganic polymers such as diatomaceous earth, talc, silicic acid, clay, metal oxide powders, water-soluble polymers such as polyvinyl alcohol, Contains gelatin and starch.

Furthermore, stirring also affects the stability of polymerization and particle size. High-speed stirring stabilizes polymerization, but the particles become smaller than necessary. On the other hand, if the mixture is stirred at low speed, it may gel and particles may not be obtained. Therefore, it is necessary to choose appropriate conditions.

However, even with these methods, the particle size that satisfies the toner, that is, the number average diameter of 10μ~
It is difficult to obtain fine particles of about 20μ. This is because, in the end, there is no sufficient way to prevent union. Therefore, in the combination of a polymerizable monomer and an inorganic dispersant, the interface of the polymerizable monomer particles is anionically charged by the anionic polymerizable monomer, while the inorganic dispersant The inorganic dispersant completely and uniformly covers the surface of the polymerizable monomer particles with strong ionic bonds to prevent coalescence, resulting in a number average diameter of 10 to 20μ. A method has been proposed to obtain particles of approximately

However, even with this method, the particle size cannot be said to be sufficiently satisfactory as a toner. This is because it is more preferable that the toner particle size distribution is narrower. In other words, as the particle size becomes uniform, the amount of charge on each particle becomes almost the same,
Therefore, stable images can be obtained. The narrower the particle size distribution, the more stable the image, the better the reproducibility of fine lines, and the less fog there will be.

Furthermore, it is extremely difficult for toner produced by this method to satisfy the conflicting properties of heat fixability, blocking property, and developability. In order to improve heat fixability, it is necessary to lower the melting temperature of the polymerized resin. For example, it is necessary to lower Tg (glass transition temperature). However, this is disadvantageous for blocking properties. In order to improve blocking properties, Tg must be at least higher than the required blocking temperature, and the higher it is, the more advantageous it is. However, the toner produced by this method has anionic groups gathered on the particle surface, but is a homogeneous polymer as a whole, so in order to improve heat fixability, the molecular weight is reduced.
When Tg is lowered, blocking properties deteriorate,
Moreover, it is also reflected in development, resulting in poor image quality. On the other hand, if the polymer is made to have a high molecular weight or crosslinked in order to improve the blocking property, then the heat fixing property deteriorates, resulting in a vicious cycle.

Therefore, the present inventors created a system containing one or more types of polymerizable monomers, dyes and pigments, polymers, and other additives as necessary, in a dispersion medium in which a cationic dispersant was dispersed. In a suspension and polymerization system, the purpose can be achieved by incorporating an anionic stainless steel copolymer into the polymerizable monomer and polymerizing it. Without being bound by theory, when an anionic polymerizable monomer is added to the monomer system in the method described above, these substances collect on the surface of the suspended particles, and a small amount of the material flows from the monomer system into the dispersion medium. It is thought that the particle size distribution is not quite narrow because the interface between the particles and the dispersion medium becomes uncertain and the suspended particles become somewhat unstable. When this is done by incorporating the anionic styrenic copolymer into the monomer system, the anionic styrenic copolymer collected on the surface of the suspended particles is transferred from the monomer system into the dispersion medium system. It is not distributed properly. This is because it has a high molecular weight. Therefore, the interface between the suspended particles becomes firm and stable, making it easier for the particle sizes to be uniform.

Furthermore, since the anionic styrenic copolymer collects on the surface of the suspended particles, the resulting particles take on a kind of shell-like form and become pseudo-capsules. That is, irrespective of the initial polymerization of the polymerizable monomer, a resin having a desired degree of polymerization can be used as the anionic styrenic copolymer for the shell. Therefore, the interior is polymerized to a relatively low molecular weight material with excellent heat or pressure fixing properties, and the anionic styrene copolymer that forms the shell is relatively high molecular weight and has good blocking properties, developability, and resistance. A resin with excellent abrasion properties can be used.

Such toner has excellent fixing properties, blocking properties, and charging properties, and provides good images.

However, the toner produced by this method has some hygroscopicity because the hydrophilic dispersant is attached to the surface. Although this toner can be used practically, it was desired to further improve the developability.

Therefore, the purpose of the present invention is to provide a method with better developability.
Furthermore, the aim is to obtain a toner that is extremely stable against changes due to humidity. In other words, by treating the suspension polymer obtained by the above production method with a silane coupling agent or a titanate coupling agent, the developability is improved. , is a method of improving moisture resistance. Specifically, in the present invention, an anionic styrenic copolymer is dissolved in a monomer system containing styrene as a polymerizable monomer, mixed while heating, and the anionic styrenic copolymer is dissolved. The heated monomer system is suspended in a heated dispersion medium containing cationic colloidal silica treated with a nitrogen-containing silanizing agent and polymerized to form polymer particles. The present invention relates to a method for producing a toner for electrostatic charge development, characterized in that the toner is produced by treating polymer particles with a silane coupling agent or a titanate coupling agent. Since a small amount of hygroscopic inorganic dispersant is attached to the surface of the above polymer, it is added at least 0.5% by weight based on the weight of the polymer.
Desirably, the hydrophilic groups in the dispersant are coupled with 1% or more of a silane coupling agent or a titanium coupling agent to prevent the hydrophilic groups from bonding with water and improve moisture absorption resistance. If the amount of silane coupling agent or titanium coupling agent used in the treatment is 0.5% or less, sufficient moisture absorption resistance cannot be obtained because a large number of uncoupled hydrophilic groups remain.

Examples of the silane coupling agent used in the present invention include vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, vinyltriacetoxysilane, N-β(aminoethyl)-
γ-aminopropylmethoxysilane, N-β(aminoethyl)-γ-aminopropylmethyldimethoxysilane, N-β-(N, vinylbenzylaminoethyl)-γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxy silane,
γ-(2-aminoethyl)aminopropyltrimethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, methyltrichlorosilane γ-methacrylocypropyltrimethoxysilane,
γ-glycidoxypropyltrimethoxysilane,
γ-mercaptopropyltritoxysilane, vinyltriacetoxysilane, γ-chloropropyltrimethoxysilane, hexamethyldisilane, vinyltris(methoxyethoxy)silane, γ-anilinopropyltrimethoxysilane, octadecyldimethyl [3-(trimethoxysilyl) ) propyl] ammonium chloride, γ-mercaptopropylmethyldimethoxysilane, etc.

Further, titanate coupling agents that can be used in the present invention include isopropyl triisostearoyl titanate, isopropyl tridodecylbenzenesulfonyl titanate, isopropyl tris(dioctylpyrophosphate) titanate,
Tetraisopropylbis(dioctylphosphite) titanate, Tetraoctylbis(ditridecylphosphite) titanate, Tetra(2,2
-diallyloxymethyl-1-butyl)bis(di-tridecyl)phosphite titanate, bis(dioctylpyrophosphate)oxyacetate titanate, bis(dioctylpyrophosphate)ethylene titanate, isopropyltrioctinonortitanate, isopropyldimethacryliso Examples include stearoyl titanate and isopropyl isostearoyl diacryl titanate.

These coupling agents can be treated by dissolving and dispersing them in an aqueous solution and immersing them in a conventional manner, dissolving them in an organic solvent containing a small amount of water and a hydrolysis catalyst, and treating them by immersing them in an aqueous solution.
Methods such as spraying an organic solvent solution for treatment can be used, but the method is not limited thereto.

It is also possible to remove the silica from the polymer particles with an alkali and then treat them using the above method.

Examples of the anionic styrenic copolymer used in the present invention include copolymers of the following anionic polymerizable monomers and the following styrenes or styrene derivatives. Specifically, the anionic styrenic copolymers include 2-acrylamide-2-methylpropanesulfonic acid, N-natylolacrylamide, methacrylic acid, acrylic acid, 2-hydroxyethyl methacrylate, and methacrylic acid. Hydroxyl groups, carboxyl groups, sulfonic acid groups such as 2-hydroxypropyl, glycidyl methacrylate, polypropylene glycol monomethacrylate, polyethylene glycol monomethacrylate, tetrahydrofurfuryl methacrylate, acid phosphooxyethyl methacrylate, maleic anhydride,
Anionic vinyl monomers having phosphoric acid groups and acid anhydride groups, styrene, o-methylstyrene, p-
Methylstyrene, 2,4-dimethylstyrene, p
Examples include copolymers with styrene or styrene derivatives such as -n, butylstyrene, p-tert-butylstyrene, p-n, dodecylstyrene, p-chlorostyrene, and p-phenylstyrene. Preferably, as shown in the examples below, the anionic styrenic copolymer has a weight average molecular weight of
The one having 30,000 to 150,000 is good. Other copolymer monomers that may be used in the cationic styrenic copolymer of the present invention include vinylnaphthalenes, ethylenically unsaturated monoolefins such as ethylene, propylene, and isobutylene; vinyl chloride, acetic acid Vinyl esters such as vinyl, vinyl butyrate, vinyl benzoate; 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, methacryl Methyl acid, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl ethacrylate, dodecyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, methacrylate α-methylene aliphatic monocarboxylic acid esters such as dimethylaminoethyl acid and diethylaminoethyl methacrylate; acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, and acrylamide;
vinyl methyl ether, vinyl ethyl ether,
Vinyl ethers such as vinyl isobutyl ether; Vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, methyl isoprovinyl ketone; N-vinyl pyrrole, N-vinyl carbazole, N-vinylindole, N-vinylpyrrolidene, etc. Examples include compounds. One or more of these may be used. Further, one or more of these polymers may be contained in the polymerizable monomer.

In the present invention, styrene is used as a polymerizable monomer, and as shown in the examples below, a vinyl monomer such as butyl acrylate monomer may also be used.

Examples of the polymerization initiator used in the present invention include azobisisobutyronitrile (AIBM), benzoyl peroxide, methyl ethyl ketone peroxide, isopropyl peroxy carbonate,
It can be carried out using cymene hydroperoxide, 2,4-dichlorylbenzoyl peroxide, lauroyl peroxide, etc.

In the present invention, a crosslinking agent may be used to form a crosslinked polymer. For example, divinylbenzene, divinylnaphthalene and their derivatives, diethylene glycol methacrylate, diethylene glycol methacrylate, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, etc., 1,2-propylene glycol, 1,3
- A general crosslinking agent such as butanediol can be used as appropriate.

Examples of the cationic dispersant used in the present invention include hydrophilic positively charged colloidal silica treated with a silane treatment agent containing nitrogen such as an amino group.

As dyes and pigments used in the present invention, commonly known dyes and pigments can be used as appropriate. Furthermore, carbon black and magnetic materials can also be used. In particular, magnetic materials should be surface-treated.

The suspension method uses a monomer system in which a polymerization initiator, anionic styrene copolymer, styrene monomer, additives, dyes and pigments, crosslinking agents, etc. are uniformly dissolved or dispersed as a suspension stabilizer, and a cationic colloidal It is dispersed in a dispersed phase, ie, a continuous phase, containing silica using a conventional stirrer, homomixer, homogenizer, or the like. Preferably, the stirring speed and time are adjusted so that the monomer droplets have the desired toner particle size, generally 30μ or less, and thereafter, the stirring is performed so that this state is maintained approximately by the action of the dispersion stabilizer. It is only necessary to carry out this process to the extent that sedimentation of the particles is prevented.

Polymerization is carried out by setting the polymerization temperature appropriately. The toner particles generated after the reaction is 0.5wt% to the toner.
Stir in a silane coupling agent aqueous solution or titanate coupling agent aqueous solution with the above concentration at room temperature for 1 to 3 hours at a speed that does not allow particles to settle,
After filtering and thoroughly washing with water, collect and dry by an appropriate method.

All known methods can be used to develop this toner. For example, two-component development methods such as the cascade method, magnetic brush method, and microtoning method; one-component development methods containing magnetic materials such as conductive one-component development method, insulating one-component development method, and jumping development method; powder Examples include cloud method and fur brush method; non-magnetic component development method in which toner is held on a toner carrier by electrostatic force and transported to a developing section for development.

Example 1 Styrene monomer 200g Styrene-maleic anhydride copolymer (8:2
Mw: 30000) 10g was heated to 60℃ and dissolved. After that, 10g of phthalocyanine blue was added and mixed for about 5 minutes in a container equipped with a high shear force mixing device such as TK Homomixer (manufactured by Tokushu Kika Kogyo). Mixed.

Next, 10 g of azobisisobutyronitrile was added. Separately add H ₂ N―CONH― to water 1000c.c.
4g of hydrophilic positively charged silica treated with CH ₂ CH ₂ CH ₂ -Si-(OC ₂ H ₅ ) ₃ was dispersed, and the above was added to the dispersion medium heated to 60°C while stirring with a TK homomixer. The slurry was added and stirred at 4000 rpm for about 1 hour.
Thereafter, this mixed system was stirred with a paddle blade to complete the polymerization, and N-β-(N-vinylbenzylaminoethyl)-γ-aminopropyltrimethoxysilane hydrochloride (SZ manufactured by Toray Silicone) was added to this suspension.
-6032) (this concentration is 2 of the polymer weight)
%) and stirred at room temperature for 1 hour to couple the dispersant on the surface of the polymer, followed by filtration, washing with water and drying to obtain a toner having a pseudo capsule structure.

The obtained toner had a number average diameter of 8.95 μm, a number distribution of 18% of particles of 6.35 μm or less, and a volume distribution of 1% of particles of 20.2 μm or more (Coulter counter aperture of 100 μm).

Also, as a result of mixing iron powder carrier-EFV250/400 with toner content of 10wt% and measuring the triboelectric charge,
It was +12.4 μcoul/g. This developer is used in a copying machine.
As a result of reversal development using an NP-5500 machine, a good image could be obtained, and stable and good images were obtained even after continuous image printing of 50,000 sheets. Furthermore, as a result of a 50°C blocking test, this toner did not cause any blocking even after more than one week. or
There is no change in image quality even at a high temperature of 32 degrees Celsius (90%).
The dispersant on the polymer surface, which had sufficient image density,
In SZ-6032, the uncoupled toner had the same image density, but fogging occurred and the triboelectric charge was lower at +6.3 μc/g. Furthermore, under high humidity conditions, fogging was noticeable and the image density was low.

Example 2 Styrene monomer 200g Copolymer of styrene and dihydroxyethyl methacrylate (w: 50000) (9:1 monomer ratio)
10 g of azobisisobutyloberonitrile, 10 g of phthalocyanine green, and 10 g of phthalocyanine green were polymerized in the same manner as in Example 1. To this was added an aqueous solution of isopropyl triisostearoyl titanate (Ajinomoto KR-TTS) in an amount of 1 wt % based on the polymer weight, and the mixture was stirred at room temperature for 2 hours, filtered, washed with water, and dried to obtain a toner.

The obtained toner had a number average diameter of 8.2 μm, 19% of the particles were 6.35 μm or less in the number distribution, and 20.2 μm or more in the volume distribution.
It was 0.5% (Coulter counter, Apatya 100μ). This was imaged in the same manner as in Example 1. The tribocharge was +14.2 μc/g, and continuous imaging was performed. Continuous image output is stable up to 10,000 images,
There was no fogging. There were also no problems in the 50°C blocking test. Furthermore, images equivalent to those obtained at room temperature and humidity were obtained even under high humidity conditions of 32°C and 90% RH.

On the other hand, the toner that was not subjected to coupling treatment with SH-6020 after polymerization had a low image density and caused fogging. Also, under high humidity conditions, fogging became noticeable and worsened.

Example 3 Styrene monomer 180g Butyl acrylate monomer 20g Styrene-methacrylic acid copolymer (9:1
w: 100000) 10g Azobisisobutyronitrile 10g BL-250 (manufactured by Titanium Industries) 60g ASA-30 (manufactured by Mitsubishi Kasei) 1g Water 1000c.c. H ₂ N-CONH-CH ₂ CH ₂ CH ₂ -Si ( 4 g of colloidal silica treated with OC ₂ H ₅ ) ₃ was polymerized in the same manner as in Example 1. Vinyltris(2-methoxyethoxy)silane (manufactured by Chitsuso Corporation, VTS-
2 g of ME) was added and stirred at room temperature for 3 hours, filtered, washed with water, and dried to obtain a toner.

The obtained toner had a number average diameter of 8.8 μm, a number distribution of 20% of particles of 6.35 μm or less, and a volume distribution of 0% of particles of 20.2 μm or more (Coulter counter, Apatya 100 μm). The tribocharge was -11.0 μc/g.
When this toner was put into a copying machine NP-400RE and an image was printed, a good image was obtained. Furthermore, the images remained good even after 2000 consecutive images were output. Also, this toner
In the 50°C blocking test, the eyelids did not block for more than one week. Also, 32℃, 90%
Even under high humidity conditions of RH, images equivalent to those obtained at room temperature and humidity were obtained.

On the other hand, the toner that was not subjected to coupling processing using VTS-ME had a low image density and caused fogging.

Furthermore, under high humidity conditions, the image density was noticeably reduced.

Example 4 Styrene monomer 200g Styrene-maleic anhydride copolymer (8.5:1.5
A toner was prepared in the same manner as in Example 1 using 10 g of V-65 (manufactured by Wako Pure Chemical Industries, Ltd.) (monomer ratio w=150000), 10 g of phthalocyanine blue, and 1.0 g of divinylbenzene. The obtained toner had a number average diameter of 8.7μm and a number distribution.
17% below 6.35μm, 1% above 20.2μm in volume distribution
(Coulter counter, 100μ aperture).

The toner is held on a toner carrier by electrostatic force and conveyed to a developing section where it is developed. A toner that is not mixed with carrier particles and does not contain a magnetic substance is developed. Image printing was performed using this method. As a result, a good image was obtained. or,
I performed continuous image output, and was able to obtain stable images up to 20,000 images. Further, this toner had no problem with blocking properties at 50°C, was well fixed in a silicone oil coating system of a fixing device at 160°C, and had no offset. In addition, good images were obtained even under high humidity conditions of 32°C and 90% RH.

Toner that was not subjected to coupling processing had poor image quality, and fog was particularly severe. Furthermore, the image density decreased at high temperatures.

Example 5 Styrene monomer 200g Styrene-maleic anhydride copolymer (8:2
Mw: 30000) 10g was heated to 60℃ and dissolved. Thereafter, 10 g of phthalocyanine blue was added and mixed for about 5 minutes in a container equipped with a high shear mixing device such as TK Homo Mixer (manufactured by Tokushu Kika Kogyo).

Next, 10 g of azobisisobutyronitrile was added. Separately add H ₂ N―CONH― to water 1000c.c.
4g of hydrophilic positively charged silica treated with CH ₂ CH ₂ CH ₂ -Si-(OC ₂ H ₅ ) ₃ was dispersed, and the above was added to a dispersion medium heated to 60°C while stirring with a TK homomixer. The slurry was added and stirred at 4000 rpm for about 1 hour.
After that, this mixed system is stirred with paddle blade stirring to complete the polymerization, and this suspension contains 1wt% of the polymer particles.
of sodium hydroxide was added, stirred at room temperature for 6 hours, filtered and washed with water to remove most of the silica. Thereafter, 200 g of a 1 wt % aqueous solution of SZ-6032 was added, stirred at room temperature for 1 hour, filtered, washed with water, and dried to obtain a toner. The obtained toner had a number average diameter of 8.95 μm, 18% of the particles were 6.35 μm or less in number distribution, and 20.2 μm in volume distribution.
The ratio was 1% (Coulter counter, aperture 100μ).

Further, the toner content was mixed with iron powder carrier EFV250/400 at 10 wt%, and the triboelectric charge was measured, and the result was +18.4 μcoul/g. As a result of reversal development of this developer using a copying machine NP-5500, a good image could be obtained, and stable and good images were obtained even after continuous printing of 50,000 sheets.

Furthermore, as a result of a 50°C blocking test, this toner did not cause any blocking even after more than one week. In addition, good images were obtained even under high humidity conditions of 32°C and 90% RH. In addition, the toner without coupling had slightly inferior image quality and caused fogging under high humidity conditions.

Claims (1)

[Claims] 1 An anionic styrenic copolymer is dissolved in a monomer system containing styrene as a polymerizable monomer, and mixed while heating to dissolve the anionic styrene copolymer. The heated monomer system is suspended in a heated dispersion medium containing cationic colloidal silica treated with a nitrogen-containing silanizing agent and polymerized to produce polymer particles, and the resulting polymer 1. A method for producing a toner for electrostatic charge development, characterized in that the toner is produced by treating particles with a silane coupling agent or a titanate coupling agent. 2. The method for producing a toner according to claim 1, wherein the anionic styrenic copolymer has a weight average molecular weight of 30,000 to 150,000. 3. The method for producing a toner according to claim 1 or 2, wherein the monomer system contains a crosslinking agent. 4. The anionic styrenic copolymer is a copolymer of styrene and an anionic vinyl monomer having a hydroxyl group, a carboxyl group, or an acid anhydride group. Toner manufacturing method.