JPH0483258A - Electrophotographic toner - Google Patents

Abstract

PURPOSE:To obtain the toner having excellent flowability and caking resistance by using fine powder of magnesium oxide subjected to a hydrophobing treatment on the surface as an additive. CONSTITUTION:The fine powder of the magnesium oxide subjected to the hydrophobing treatment on the surface is added and mixed to and with toner particles. The amt. of the addition is preferably in a range of 0.1 to 20wt.%, more particularly preferably 0.3 to 5wt.% of the weight of the toner. A hydrophobic layer is formed on the surface of the fine powder of the magnesium oxide subjected to the hydrophobing treatment in this case and, therefore, the water absorptivity is low and secondary flocculation hardly arises. Flocs are less formed at the time of mixing of the additive with the toner particles and, therefore, the easy dispersion is possible. The excellent flowability and caking resistance are imparted to the toner by the addition in a relatively small amt. The resulted electrophotographic toner has good electrostatic chargeability and lower environmental dependency.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a toner for developing electrostatic images used for development in electrophotography and electrostatic recording.

[Prior art and problems to be solved by the invention] In electrophotography, an electrostatic image formed on a photoreceptor is usually developed using resin powder containing pigment, and the resulting visible image is transferred onto transfer paper. The image is then transferred to the printer and fixed using a heated roller, etc. Further, the photoreceptor is cleaned in order to form an electrostatic charge image again.

In order to have excellent process compatibility, the toner used needs to have excellent fluidity, caking resistance, fixing properties, charging properties, and cleaning properties. In particular, liquidity,
Inorganic fine powders are sometimes added to toner particles to improve caking resistance.

However, these fine powders have a large effect on charging properties. For example, commonly used silica-based fine powders have strong negative polarity (which significantly reduces the charging performance of positively charged toner, resulting in a large difference in charging performance between summer and winter environments. As a result, background fog and poor density reproduction may occur.

It is also known to add fine machinenium oxide powder (Japanese Unexamined Patent Publication No. 54-14742, etc.), but there is a problem that water absorption is high at high humidity.

Further, the dispersibility of the inorganic fine powder also has a large effect on the toner properties. If the dispersion is uneven, desired characteristics such as fluidity and anti-caking properties may not be obtained, or cleaning may become insufficient, resulting in toner sticking to the photoreceptor, causing image defects in the form of black dots. There was something like that.

The present invention aims to improve the above-mentioned drawbacks in the conventional technology.

That is, an object of the present invention is to provide a toner with excellent fluidity and caking resistance. Another object of the present invention is to provide a toner with excellent charging properties and environmental stability. Still another object of the present invention is to provide a toner that is less likely to produce black dot-like image quality defects.

[Means for Solving the Problems] The above object of the present invention is to make toner particles containing a colorant in a binder resin contain magnesium oxide fine powder whose surface has been subjected to a hydrophobization treatment. achieved by.

Hereinafter, the electrophotographic toner of the present invention will be explained in detail.

In the present invention, the magnesium oxide fine powder whose surface has been subjected to a hydrophobizing treatment is obtained by treating the magnesium oxide fine powder with a hydrophobizing agent.

Any type of fine magnesium oxide powder can be used, but the primary particle size of the fine magnesium oxide powder is preferably 0.3 mm or less, particularly 0.3 mm or less.

Effective hydrophobizing agents that can be used in the present invention include titanate coupling agents, long-chain organic acids, and long-chain alcohols.

Typical titanate coupling agents include, for example, isopropyl triisostearoyl titanate, isopropyl tridecylhensensulfonyl titanate, isopropyl tris(dioctyl pyrophosphate) titanate, and tetraisopropyl bis(dioctyl phosphite). ) titanate, tetraoctyl bis(ditridecyl phosphite) titanate, tetra(2,2
-noallyloxymethyl-1-butyl)bis(didodecyl)phosphite titanate, isopropyltri(N-
Examples include aminoethyl-aminoethyl) titanate.

Typical long-chain organic acids include saturated fatty acids such as lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, valmitic acid, margaric acid, stearic acid, nonadecanoic acid, and montanic acid, nistearol. acids, normal acetylene fatty acids represented by behenolic acid - ω-phenyl fatty acids represented by Monna C6H5 (CH2) nC0OH; - ω-cyclohexyl fatty acids represented by Monna C5Hn (CH2) nC0OH, and these fatty acids Examples include alkali metal salts.

Furthermore, typical long-chain alcohols include:
Examples include pentadecanol, cetyl alcohol, heptadecanol, octadecanol, nonadecanol, and eicosanol.

These hydrophobizing agents can be used alone or in combination of two or more.

The amount of the hydrophobizing agent to be treated is 0.1 to 20% by weight, more preferably 0.3 to 1% by weight, based on the magnesium oxide fine particles.
It is appropriate to set it to 0% by weight.

Usually, magnesium oxide fine powder is prepared by seawater method, i.e.
Magnesium hydroxide obtained from seawater is mainly used by heating and calcining, and it has a problem of high water absorption in high humidity. However, in the present invention, the surface is subjected to hydrophobic treatment The fine magnesium oxide powder has a hydrophobic layer formed on its surface, so it has low water absorption and is resistant to secondary agglomeration.

In the present invention, the toner to which the hydrophobically treated magnesium oxide fine powder is added may be a known toner containing a coloring agent in a binder resin.

Binder resins include styrenes such as styrene, chlorostyrene, and vinylstyrene, monoolefins such as ethylene, propylene, butylene, and isoprene, vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate, and vinyl butyrate, and alliclic acid. Methyl, ethyl acrylate,
α-methylene aliphatic monocarphonic acid esters such as butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate, vinyl methyl ether, vinyl ethyl ether, Examples include vinyl ethers such as vinyl butyl ether, homopolymers or copolymers of vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, vinyl isopropenyl ketone, etc. Particularly representative binder resins include polystyrene, styrene, etc. - Alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyethylene, and polypropylene. Further examples include polyester, polyurethane, Epoquin resin, silicone resin, polyamide, modified cosine, and paraffins.

In addition, toner coloring agents include carbon black, magnetic powder, dyes and pigments such as nicrosine dye, aniline blue, calcoyl blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue loride, and phthalocyanine. Blue, Malachite Gnon Oxalate, Lamp Black, Loin Bengal, C, 1, Pigment Red 48:L C
,1, Pigment Let 122, C,l Pigment Red 571, C,l Pigment Yellow 97
, C] Pigment Yellow 12, C,1, Pigment Blue 15:1° CI Pigment Blue 153, etc. can be exemplified as representative examples.

These toners may contain known additives such as charge control agents and waxes, if desired.

In the present invention, the average particle size of the toner particles is preferably less than about 30 mm, particularly in the range of 3 to 20 mm.

. The electrophotographic toner of the present invention can be obtained by adding the hydrophobically treated magnesium oxide fine powder to the toner particles and mixing them. The amount of the hydrophobically treated magnesium oxide fine powder added is preferably in the range of 01 to 20% by weight, particularly 0.3 to 5% by weight, based on the toner. Further, the mixing can be performed by a known means such as a Henschel mixer or a V-type blender.

The electrophotographic toner of the present invention may be a one-component toner developer that does not use a carrier, or may be a two-component developer that uses a carrier.

However, it is preferably used as a two-component developer.

When using a carrier, there are no particular limitations as long as it is a known carrier, and iron powder carriers, ferrite carriers, surface-coated ferrite carriers, magnetic powder dispersed carriers, etc. can be used.

[Examples] Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited in any way by these Examples. Note that "part" means part by weight.

Example 1 Hydrophobization treatment of magnesium oxide fine powder.

Magnesium oxide fine particles 100 parts (average -
(particle size: 0.05-0.10 uM) Isoprobyltroidecylbenzene 20 parts Sulfonyl titanate (9S) Solvent (dehydrated toluene) 1000 parts The above materials were placed in a flask and stirred at 60°C for 2 hours. Thereafter, the solvent and unreacted isopropyltridecylbenzenesulfonyl titanate were separated by filtration, and the fine magnesium oxide powder was dried under reduced pressure at 60°C overnight, and then pulverized to obtain a fine hydrophobized magnesium oxide powder. Ta.

Production of toner particles Styrene-n-butyl acrylate 88 parts Copolymer (723) Resin Carbon black (Black 10 parts Perls L1 manufactured by Cahot) Nigrosine dye (Bontron N-03) 2 parts The above ingredients were mixed in a Banbury mixer. After kneading, the mixture was finely pulverized and classified to produce toner particles having an average particle size of 11 m+.

To 100 parts of the above toner particles, 2 parts of the hydrophobized magnesium oxide fine powder obtained as described above is added, mixed with a Henschel mixer, and adhered to the surface of the toner particles for use in electrophotography. A toner was produced.

On the other hand, styrene-n-butyl methacrylate copolymer 3
0% by weight and 70% by weight of magnetite (EPTI (1 (10) manufactured by Toda Kogyo Co., Ltd.) were kneaded, crushed, and classified to obtain a carrier having an average particle size of 35%.

An electrophotographic developer was prepared by mixing 10 parts of the above toner and 90 parts of carrier, and an electrophotographic developer was prepared using an electrophotographic copying machine (FX-507).
A running test of 50,000 sheets and an environmental test were conducted using 50,000 sheets (manufactured by Fuji Serotox). The results are shown in Table 1 below.

Example 2 Hydrophobization treatment of magnesium oxide fine powder: 100 parts of magnesium oxide fine particles (average particle size 0.5
~0.10 mochi) stearic acid
20 parts Solvent (dehydrated toluene) 1000
The above materials were placed in a flask, heated and stirred, and refluxed for 2 hours. Thereafter, the solvent and unreacted stearic acid were separated by filtration, and the magnesium oxide fine powder was dried under reduced pressure at 120° C. overnight, and then ground to obtain a hydrophobized magnesium oxide fine powder.

Manufacture of toner particles: To 100 parts of the same toner particles as in Example 1, 2 parts of the hydrophobized magnesium oxide fine powder obtained as described above was added and treated in the same manner as in Example 1. Thus, an electrophotographic toner was produced.

An evaluation test was conducted in the same manner as in Example 1 using this electrophotographic toner. The results are shown in Table 1.

Comparative Example 1 In Example 1, instead of the hydrophobized magnesium oxide fine powder, unhydrophobized magnesium oxide fine powder (average primary particle size 0.05 to 0.1 ha+) was used.
) An electrophotographic toner was produced in the same manner as in Example 1 except that 2 parts were used.

An evaluation test was conducted in the same manner as in Example 1 using this electrophotographic toner. The results are shown in Table 1. Table 1 [Effects of the Invention] The fine magnesium oxide powder of the present invention, whose surface has been subjected to hydrophobization treatment, has a hydrophobization layer formed on the surface, so it has low water absorption and It has the characteristic of being difficult to agglomerate. Therefore, when mixed with toner particles, it can be easily dispersed because there are few aggregates, and excellent fluidity and caking resistance can be imparted to the toner with a relatively small amount added. . Further, the obtained electrophotographic toner has good charging properties and has little environmental dependence.

Patent applicant Fuji Serotox Co., Ltd. Agent
Patent attorney Tsuyoshi Seibe

Claims (3)

[Claims] (1) An electrophotographic toner consisting of toner particles consisting of at least a binder resin and a colorant, and an additive, characterized in that fine magnesium oxide powder whose surface has been subjected to a hydrophobic treatment is used as the additive. Toner for electrophotography. (2) The electrophotographic toner according to claim 1, wherein the hydrophobization treatment is treatment with a titanate coupling agent. (3) The electrophotographic toner according to claim 1, wherein the hydrophobization treatment is treatment with a long-chain organic acid or a long-chain alcohol.