JPH04345169A - Toner for developing electrostatic charge image - Google Patents

Abstract

PURPOSE:To provide a toner having excellent electrification stability and not causing scattering, fog, etc. CONSTITUTION:This toner for developing an electrostatic charge image consists essentially of a thermoplastic resin, a colorant and a post-treating agent. The post-treating agent is hydrophilic silica and hydrophobic titania or hydrophilic silica and hydrophobic alumina.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is applicable to electrophotography, electrostatic recording,
The present invention relates to toner for developing electrostatic images in electrostatic printing and the like.

0002

[Prior Art] In electrophotography, a cascade development method using a mixed developer of toner and carrier (United States Patent (USP) No. 2297691, USP No.
No. 618,552) or magnetic brush development (USP No. 2,832,311), or touchdown development using a toner-only developer (USP No. 412).
No. 1931), non-magnetic component development method (USP No. 3731)
No. 146), etc., or by visualizing the electrostatic charge image by reversal development to obtain a high-quality stable image.

[0003] Toners used for electrophotography generally have post-processing agents such as silica (silicon dioxide), titania (titanium dioxide), or alumina (aluminum oxide) added to improve toner fluidity and cleaning properties. is used. Since silica is the most easily available, it is mainly added as a general-purpose post-treatment agent, but silica alone has problems such as high initial charge level, environmental instability, and reduced fluidity due to embedding. In order to prevent these problems, toners have been proposed in which a combination of titania or alumina is added in addition to silica (for example, Japanese Patent Laid-Open No. 60-1367
Publication No. 55)

0004

[Problems to be Solved by the Invention] However, even with such toners, problems such as toner charge-up, environmental instability, toner scattering, fogging, and texture still exist, and improvements in these problems are not yet possible. desired. The purpose of the present invention was made in view of the above circumstances, and
It is an object of the present invention to provide a toner for developing electrostatic images that can form images with excellent image quality such as texture, without causing problems such as environmental stability, toner scattering, and fogging.

[0005]

[Means for Solving the Problems] The present invention provides a toner comprising at least a thermoplastic resin, a colorant, and a post-processing agent, in which the post-processing agent includes hydrophilic silica and hydrophobic titania, or hydrophilic silica and hydrophobic oxidized The present invention relates to an electrostatic charge developing toner characterized by being made of alumina.

[0006] In the present invention, hydrophilic silica refers to silica that has not been subjected to hydrophobization treatment. Furthermore, hydrophobic titania or hydrophobic alumina refers to titania or alumina treated with a hydrophobizing agent.

When silica, alumina, titania, etc. are added as a toner post-treatment agent, a combination of hydrophilic silica and hydrophobic titania or hydrophilic silica and hydrophobic alumina is used. By doing so, the electrical resistance values of the two become similar, and accordingly, the charge levels also become the same. Therefore, silica and titania or silica and alumina are less likely to coagulate due to Coulomb force, so each post-processing agent such as silica and titania adheres uniformly to the toner. As a result, not only sufficient toner fluidity is ensured, but also uniform charging is obtained, toner scattering is less likely to occur, and background fogging and the like are prevented. Furthermore, image defects due to silica/titania or silica/alumina aggregates (
There is no occurrence of white spots, etc., and a high-quality image with good texture is formed.

Hydrophilic silica has a size that is usually added to toner, that is, a primary particle size of 5 to 20
Silica T-30 (manufactured by Wacker Co., Ltd.), #200 (manufactured by Nippon Aerosil Co., Ltd.) and the like are commercially available. By adding silica, the fluidity of the developer can be improved and the toner charge amount can be increased.

Hydrophilic silica is used in an amount of 0.1 to 1.0% by weight, preferably 0.1% by weight based on the toner, although it depends on the type of toner.
Add ~0.5% by weight. If the amount is less than 0.1% by weight, there will be no effect of adding silica, and if it exceeds 1.0% by weight, environmental fluctuations will increase, charge-up phenomenon will occur under low humidity, and image density will be insufficient. arise.

In addition to hydrophilic silica, the present invention adds hydrophobic titania or hydrophobic alumina particles. The addition of titania or alumina causes problems, especially in low-viscosity polyester toners, such as embedding of silica in the toner, which reduces fluidity during printing, and problems that the amount of charge caused by the addition of silica becomes too high, and the environment. Can improve stability issues.

Titania or alumina is preferably 1
The particle size used is 10 to 100 mμm.

The amount of titania and alumina added to the toner is 0.2 to 3.0% by weight, preferably 0.3 to 2.0% by weight.
It is 0% by weight. If it is less than 0.3% by weight, the effect of adding these fine particles cannot be obtained, and if it is more than 3.0% by weight, the charging level becomes too low, causing problems such as fogging and further worsening the texture of the image. This problem arises.

[0013] Titania or alumina added to the toner is hydrophobized to improve environmental stability. As the hydrophobizing agent, various coupling agents such as silane type, titanate type, aluminum type, zircoaluminate type, silicone oil, etc. are used. Examples of silanes include chlorosilane, alkylsilane, alkoxysilane, and silazane.

Specifically, for example,

[Chemical formula 1]

[Case 2] etc. can be mentioned.

[0015] For titanate series, for example,

[Chemical formula 3]

[C4]

[C5] etc. can be mentioned.

[0016] For silicone oil systems, for example,

[C6]

[C7]

[Chemical formula 8] etc., and is not particularly limited.

The following method is used to treat the surface of the post-treatment agent powder using a hydrophobizing agent. First, a hydrophobizing agent alone or tetrahydrofuran (THF), toluene,
Mix and dilute with a solvent such as ethyl acetate, methyl ethyl ketone, or acetone, and while forcibly stirring the post-treatment agent powder with a blender or the like, add the diluted solution of the coupling agent dropwise or by spraying and mix thoroughly. Next, the obtained mixture is transferred to a vat or the like and placed in an oven to heat and dry. Then, stir again in a blender to thoroughly crush the mixture. In such a method, each hydrophobizing agent may be used simultaneously. In addition to such a dry method, there is also a wet treatment method in which a post-treatment agent is immersed in a solution of a hydrophobizing agent dissolved in an organic solvent, dried, and crushed. Further, it is preferable that the post-treatment agent is heat-treated at 100° C. or higher before the hydrophobization treatment described above.

[0018] The amount of the hydrophobizing agent to be used needs to be adjusted depending on the type of post-treatment agent, etc.
5% by weight, preferably 0.2-3% by weight. 0.
If it is less than 1% by weight, there is no hydrophobizing effect, and if it is more than 5% by weight, many aggregates of post-processing agents will occur, and the original effects of the post-processing agent, such as improving the fluidity of the developer, will be inhibited.

In order to incorporate the surface-treated post-processing agent of the present invention into the toner, the toner and the post-processing agent are mixed and stirred in a normal ratio in a blender or mixer to uniformly apply the post-processing agent on the toner surface. A known method may be applied, such as attaching it to the surface. Further, the post-processing agent may be mixed in at the same time when the toner is kneaded to uniformly disperse it inside the toner (internal addition). When a toner is prepared by a polymerization method, a method can also be used in which a post-processing agent is added during polymerization so that the post-processing agent is incorporated simultaneously with the formation of the toner. Furthermore, it is also possible to use a method in which a post-treatment agent is fixed to the toner surface by mechanical shearing force using a hybridization system, mechanofusion system, or the like.

The toner to which the post-processing agent of the present invention is added is generally fine particles consisting of at least a binder resin such as acrylic resin, polystyrene resin, polyester resin, styrene-acrylic copolymer resin or epoxy resin, and a colorant, and a magnetic carrier. There are toners that are used as two components together with particles, toners that are used as a non-magnetic component, and toners that are used as a toner that contains a magnetic agent inside the toner (magnetic toner), but the present invention does not apply to any of them. It can also be applied to the toner used in the method. In particular, the present invention is effectively applied to a translucent toner made of a resin with low viscosity, and such a toner is made of at least a polyester resin and a colorant.

Examples of the polyester resin include polyols such as bisphenols, ethylene glycol, triethylene glycol, 1,2-propylene glycol, and 1,4-butanediol, and maleic acid,
Examples include those obtained by polycondensing aliphatic unsaturated dibasic acids such as itaconic acid, dibasic acids such as phthalic acid, terephthalic acid, isophthalic acid, malonic acid, and succinic acid. In particular, from the viewpoint of improving environmental stability, it is preferable to use a modified polyester resin in which an unsaturated polyester is present in a polyester resin and an aromatic vinyl monomer is graft-polymerized to the unsaturated polyester. The proportion of polyester in this modified polyester is 50% by weight or more, preferably 60 to 90% by weight.

[0022] Examples of the aromatic vinyl monomer include styrene, α-methylstyrene, vinyltoluene, p-ethylstyrene, and the like. Other vinyl monomers can also be used in conjunction with aromatic vinyl monomers, e.g.
Methacrylic acid alkyl esters such as methyl methacrylate, butyl methacrylate, octyl methacrylate, and styryl methacrylate; Acrylic acid alkyl esters such as ethyl acrylate, propyl acrylate, butyl acrylate, and octyl acrylate; Acrylonitrile, acrylamide; Alternatively, amino group-containing vinyl monomers such as dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl acrylate, and dimethylaminopropylmethacrylamide can be used.

In the present invention, the polyester resin constituting the toner has a number average molecular weight (Mn) of 250.
0-12000, dispersity (Mw/Mn) 2-6, glass transition point (Tg) 50-70°C, melting point (Tm) 8
A temperature of 0°C to 120°C is suitable. When these physical properties are not satisfied, the toner cannot have sufficient light transmittance, and its fixing properties and heat resistance are reduced.

As the coloring agent, for example, as a yellow coloring agent, C.I. I. Pigment Yellow 12, C. I. Pigment Yellow 13 etc. as a red colorant. I. Pigment Red 122, C. I. Pigment Red 57:1, C.I. as a blue colorant. I. Pigment Blue 15 and the like can be mentioned, but the colorant is not limited to these, and pigments, dyes, etc. of various colors conventionally used in translucent color toners can be used.

In addition to the colorant, desired additives such as a charge control agent may be added to the toner of the present invention. The toner of the present invention uses colorants and other necessary additives in amounts conventionally used in toners, and is usually processed by kneading, pulverizing, etc.
The toner is prepared as a toner having an average particle size of 4 to 25 μm. The present invention will be explained below using examples.

[0026]

【Example】

Manufacturing example of thermoplastic resin for toner (binder resin:
Production of vinyl modified polyester resin) 68 parts by weight of polyoxyethylene (2)-2,2-bis(4-hydroxyphenyl)propane, 16 parts by weight of isophthalic acid
parts by weight, 16 parts by weight of terephthalic acid, 0.0 parts by weight of maleic anhydride.
A flask was charged with 3 parts by weight and 0.06 parts by weight of dibutyltin oxide, and the reaction was continued at 230° C. for 24 hours under a nitrogen atmosphere and then taken out. The weight average molecular weight of the obtained unsaturated polyester resin was 10,600.

50 parts by weight of this unsaturated polyester resin,
50 parts by weight of xylene was charged into a flask and dissolved. The temperature was raised until the xylene refluxed, and a solution of 13 parts by weight of styrene, 0.4 parts by weight of azobisisobutyronitrile dissolved in 2 parts by weight of methyl methacrylate was added dropwise under nitrogen atmosphere over about 30 minutes while the xylene was refluxing. . Keep warm for 3 hours after dropping.
After distilling xylene under reduced pressure, the resin was taken out, and the weight average molecular weight was 13,100, and the melt viscosity at 100°C was 6x.
A binder resin having 104 poise and a glass transition temperature of 63°C was obtained.

However, the melt viscosity is a value measured using a Shimadzu flow tester CFT-500 under the conditions of a nozzle diameter of 1 mm, a nozzle length of 1 mm, a load of 30 kg, and a temperature increase rate of 3° C./min.

Example of manufacturing carrier Styrene consisting of styrene, methyl methacrylate, 2-hydroxyethyl acrylate, and methacrylic acid
Acrylic copolymer (1.5:7:1.0:0.5)8
0 parts by weight of butylated melamine resin was diluted with toluene to prepare a styrene acrylic resin solution having a solid ratio of 2%.

[0030] Calcined ferrite powder (F-300
; Average particle size: 50 μm, bulk density: 2.53 g/cm3;
The styrene acrylic resin solution was applied using a spiller coater (manufactured by Okada Seiko Co., Ltd.) and dried. The obtained carrier was baked at 140° C. for 2 hours in a hot air circulation oven. After cooling, the ferrite powder bulk was crushed using a sieve shaker equipped with screen meshes with openings of 210 μm and 90 μm to obtain resin-coated ferrite powder. This ferrite powder was subjected to the above coating, firing, and crushing process three more times to obtain a resin-coated carrier. The average particle size of the obtained carrier was 52 μm, and the electrical resistance was about 3×10 10 Ωcm.

Example 1

Part by weight: Styrene acrylic modified polyester resin obtained above 100
・Carbon black MA #8 (manufactured by Mitsubishi Chemical Corporation)
3. Charge control agent (Bontron E-84, manufactured by Orient Chemical Co., Ltd.)
3 The above materials were thoroughly mixed using a Henschel mixer, kneaded using a twin-screw extruder, and then cooled. The mixture is roughly pulverized with a feather mill, and then a jet pulverizer and an air classifier are used to reduce the particle size to 5 to 25 μm (average particle size 10.
5 μm) toner particles were obtained.

Next, 0.2% by weight of hydrophilic silica T-30 (manufactured by Wacker) and 1.0% by weight of hydrophobic titania MT-600BS (manufactured by Teika) were added and mixed in a Henschel mixer to obtain toner (2). Ta.

Example 2 A toner was obtained in the same manner as in Example 1, except that the carbon black used in Example 1 was changed to a cyan pigment, Lionol Blue FG-7350 (manufactured by Toyo Ink Manufacturing Co., Ltd.). The obtained toner is referred to as toner (■).

Example 3 Thermoplastic polyester resin
100 parts by weight Molecular weight (Mn: about 6100, Mw: about 202500) Carbon black MA100 (manufactured by Mitsubishi Chemical Industries, Ltd.)
4 parts by weight Spiron black TOH (manufactured by Hodogaya Chemical Co., Ltd.) 3 parts by weight - Viscol 550P (manufactured by Sanyo Chemical Industries, Ltd.)
Toner particles were produced in the same manner as in Example 1 using 5 parts by weight of the above materials, and post-treated. The obtained toner is referred to as toner (■).

Example 4 A toner was obtained in the same manner as in Example 2, except that the hydrophobic titania used in Example 2 was replaced with hydrophobic alumina RXC (manufactured by Nippon Aerosil Co., Ltd.). The obtained toner is referred to as toner (■).

Comparative Example 1 The hydrophilic silica used in Example 1 was replaced with hydrophobic silica R.
A toner was obtained in the same manner as in Example 1 except that -812 (manufactured by Nippon Aerosil Co., Ltd.) was used. The obtained toner is referred to as toner (■).

Comparative Example 2 A toner was obtained in the same manner as in Example 1 except that the amount of hydrophilic silica used in Example 1 was changed to 1.2% by weight. The obtained toner is referred to as toner (■).

Comparative Example 3 A toner was obtained in the same manner as in Example 2, except that the hydrophobic titania used in Example 2 was replaced with hydrophilic titania MT-600B (manufactured by Teika). The obtained toner is referred to as toner (■).

Evaluation Toner samples ① to ① and carrier were mixed at a weight ratio of 8/92 to prepare a developer. This developer is used as toner■,
■、■、■～■ is CF-70 (manufactured by Minolta Camera Co., Ltd.),
Toner ■ was used with an EP-5400 (manufactured by Minolta Camera Co., Ltd.) copying machine.
), HH (30° C., 85%) and subjected to a printing durability test of 5,000 sheets, and image evaluation (fogging on the image, texture on the image, image density) was performed and the amount of charge was measured. The fluidity of the toner itself was also measured.

- Fog on images As described above, images were produced using the above-mentioned copying machine using various toner and carrier combinations. Regarding fog on images, toner fog on white background images was evaluated and ranked. A rank of △ or higher is practically usable, but a rank of ○ or higher is desirable.

- Texture on images As described above, images were printed using the above-mentioned copying machine using various toner and carrier combinations. Regarding the texture on the image, the texture on the half image was evaluated and ranked. A rank of △ or higher is practically usable, but a rank of ○ or higher is desirable.

- Image density (I.D.) Copying is performed under the same conditions as above under appropriate exposure conditions, and the I.D. D
．． We conducted an evaluation. The image density of the solid area was measured using a Sakura densitometer and ranked. A rank of △ or above is practically usable, but a rank of ○ or above is desirable.

-Evaluation of toner fluidity Ranking was done as follows based on apparent bulk specific gravity [g/cc]. 0.360 or more ○0.
340-0.360 △0.340 or less × △ rank or higher is practical, but ◯ rank is preferable. The above results are shown in Table 1 below.

[0044]

[Table 1]

[0045]

Effects of the Invention: By adding hydrophilic silica and hydrophobic titania, or hydrophilic silica and hydrophobic alumina to toner according to the present invention, charging properties are stabilized, toner scattering is prevented, and an excellent fog-free product is obtained. An image can be formed.

Claims (1)

[Claims] 1. A toner comprising at least a thermoplastic resin, a colorant, and a post-processing agent, characterized in that the post-processing agent is hydrophilic silica and hydrophobic titania, or hydrophilic silica and hydrophobic alumina oxide. Toner for developing electrostatic images.