JPS6032061A - Magnetic toner - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic toner for developing electrostatic images formed in electrophotography. More specifically, the present invention relates to a magnetic toner that provides good image density.

Conventional Shizuka 1! As a method for developing a charged image, a one-component developing method using a so-called magnetic toner in which fine magnetic powder or the like is dispersed in a resin is widely known. This one-component development method using magnetic toner differs from the two-component development method in that it does not require a special carrier, so there is no need to adjust the toner concentration, and it has the advantage that the entire developing device can be made compact. have

However, when this was used in a copying device for developing image transfer, there were the following layers.

In other words, there are conductive and insulating toners, but when conductive magnetic toner is used in the above-mentioned copying apparatus, charges with the opposite polarity to the electrostatic charge image are induced in the toner. Although development is possible, in the transfer process, the transfer paper is charged to the opposite polarity to the toner using corona discharge, etc. At that time, the charge passes through the transfer paper and changes the polarity of the toner. Transfer efficiency decreases. Also,
The resulting image itself is also likely to be blurred or uneven.

On the other hand, when an insulating magnetic toner is used in the above-mentioned copying apparatus, the problems during transfer are solved and a good transferred image can be obtained.

However, it becomes difficult to inject charge into the toner due to the electrostatic charge image formed on the photoreceptor, or the friction between the toner particles and the friction between the toner particles and the developing sleeve etc. is not sufficient. Since the amount of triboelectrification of the particles becomes low, developability deteriorates and sufficient image density cannot be obtained.

The inventors of the present invention have kept this in mind and as a result of intensive study,
The present inventors have discovered that the intended purpose can be achieved by a magnetic toner using hatsumode having an electron-donating group and an electron-withdrawing group, and have completed the present invention.

'As the magnetic toner as a component of the magnetic toner of the present invention, various known magnetic toners can be used. Example Lir! ,
Fine powder of metals such as iron, manganese, nickel, konorut, chromium, etc., alloys and oxides of iron such as ferrite, magnetite, cobalt, nickel, manganese, etc., garnets such as yttrium-iron, etc., aluminum-manganese Ferromagnetic alloys such as alloys can be used alone or in combination.

The particle size of these magnetic powders is FiO,/-1μ, preferably 0
．． ．． Preferably, it is in the range of 2 to lμ.

The resin used in the present invention has an electron donating group and an electron withdrawing group. In the present invention, a resin having an electron-donating group and an electron-withdrawing group in seven resin molecules may be used, or a mixture of a resin having an electron-donating group and a resin having an electron-withdrawing group may be used.

A resin having an electron-donating group and an electron-withdrawing group is a compound having an electron-donating group and an unsaturated double bond that can undergo addition polymerization. It is possible to copolymerize with these compounds by copolymerizing both with a compound having a possible unsaturated double bond, or by polymerizing each alone, and furthermore, when carrying out the above copolymerization or Fi polymerization. It can be easily obtained by copolymerizing another compound having an unsaturated double bond according to a known method.

Examples of the compound having an electron-donating group and an unsaturated double bond capable of addition polymerization include propyl 3-aminoacrylate 1. ? -N,N-diethylaminopropyl acrylate, J-kl, H-dimethylaminoethyl methacrylate, vinylpyrrolidine, vinylpyridine, etc., compounds having a 7' to tertiary amine group, or acrylamide, H, N-diethylacrylamide, N-vinylpyrrolidone, N-methylmethacrylamide, etc.; 1-1
Compounds having a tertiary to tertiary amide group, preferably compounds having a tertiary to 1' tertiary amino group, particularly preferably j-4,N-diethylaminopropyl acrylate, J-N,N-dimethyl Examples include ethyl aminomethacrylate and vinylpyridine.

Examples of compounds having an electron-withdrawing group and an unsaturated double bond capable of addition polymerization include compounds having a nitro group such as nitro-substituted styrene, nitro-substituted vinyltoluene, and nitro-substituted vinylnaphthalene, chlorostyrene, and fluorostyrene. , compounds with a norogen atom such as chloroprene, compounds with a carboxyl group such as acrylic acid, methacrylic acid, maleic acid, acrylonitrile,
A compound having a nitrile group such as methacrylonitrile i, or an acid anhydride such as maleic anhydride, preferably a compound having a nitro group, a compound having a halogen atom,
Compounds having a carboxyl group, particularly preferably mononitro-substituted styrene, poly-rorostyrene, chloroprene, acrylic acid, and methacrylic acid.

Other compounds having an unsaturated double bond that can be copolymerized with the above-mentioned electron-donating or electron-withdrawing group include styrene, α-methylstyrene, divinylbenzene, vinylnaphthalene, and vinylnaphthalene. Vinyl aromatic compounds such as.

Alkyl esters of acrylic acid or methacrylic acid such as methyl acrylate, methyl methacrylate, butyl methacrylate, hexyl acrylate, citalohexyl acrylate, phenyl acrylate, and phenyl methacrylate, preferably styrene and α-methylstyrene. I get kicked.

The weight ratio of the compound component having an electron-donating group and the compound component having an electron-withdrawing group is 0. It is preferable to use them in a ratio ranging from t to 10:l. Depending on the balance between the electron-donating group and the electron-withdrawing group in the resin Φ, the toner as a whole has a positive or negative polarity. The number of compound components having groups is relatively increased. Specifically, the weight ratio of the compound component having an electron-withdrawing group to the compound component having an electron-donating group is 0.35 to 1, t:l.

Preferably, it is used in a ratio of Fi/-3:l. When developing a negative latent image on a photoreceptor such as zinc oxide, a relatively large amount of a compound component having an electron donating group is used. Specifically, a compound component having an electron donating group and a compound having an electron withdrawing group are used. It is preferred to use the components in a weight ratio in the range /-10:i.

In addition, when using other copolymerizable compounds, the compound component having an electron-donating group and the compound component having an electron-withdrawing group are 0 to 90 parts by weight, preferably 50 to 90 parts by weight of the other copolymerizable compound. g.

The total amount thereof is preferably 4 (7-10" parts) per part dose, preferably in the range of Sθ to -0 parts by weight.

Such an invention? Tree-〇 molecular weight is usually Mt average molecular weight to:oo'o to 10. ooσ〜3θo, oo
In particular, those in the range of δ0θ to 3θ4θOθ can be suitably used.

In the present invention, the above-mentioned resin may be a known resin.

For example, homopolymers such as EVA, styrene, vinyl ester, α-, methylstyrene, α-chlorostyrene, and vinyl 7-talene, or combinations of these with butyl acrylate, butyl methacrylate, divinylbenzene, etc. A copolymer or the like may also be used in combination.

At that time, the total amount of the compound having an electron-donating group and the compound having an electron-withdrawing group is A O-/
It is preferable to use them in combination in such a range that ON'Ik%, preferably Sθ to −0XIk%.

The ratio of the resin and magnetic powder used is usually 73 to 50% resin.
The magnetic powder is selected from a range of -40 parts by weight based on the magnetic powder 2.

The magnetic toner system of the present invention may be made of, for example, well-known carbon black, 7-thalocyanine pigments, indolrenine pigments, xanthine pigments, aminotriazoline pigments, ann, tracetic pigments, etc., in order to change the color tone of the toner. Organic pigments, θ, /−/μ and inorganic pigments may be added. Further, in order to improve the fluidity of the toner, several tens of micrometers of titania, alumina, silica, etc. may be added as an aerosol.

1. To widen the fixing temperature during roll fixing 1.
Various low molecular weight p-waxes such as low molecular weight polyethylene, low molecular weight polypropylene, etc. may be added.

The total amount of these additives, resin and magnetic powder ioθ
It is used in a ratio of 10 parts by weight or less to parts by weight.

The magnetic toner can be obtained by a known method such as a pulverization method in which the above-mentioned components are kneaded in a kneader or the like, cooled, and then pulverized and classified, a spray dryer method, a microcapsule method, and the like.

The average particle size of the magnetic toner particles is usually preferably j~-〇μ''.The electric resistance is determined by placing the toner in a cylinder made of acrylic resin with a diameter of 1.6 cIIL to a thickness of about 0.2 mm. When measured by injecting and applying a load of 7 da Og and applying a DC voltage of 10,000 v/cIrL to the upper and lower TFj and poles of the cylinder, it is approximately /,!714 Ωcr
It is preferable that it is above IL.

The magnetic toner of the present invention provides good image density. For example, even if a magnetic toner is prepared with a resin containing only electron-donating groups and a negative latent image on a photoreceptor such as ZnO is developed, a very low image density cannot be obtained; However, when a certain amount of electron-withdrawing group is contained, the image density is significantly improved. This is probably because, compared to the case where only electron-donating groups are present on the surface of the toner, the coexistence of some electron-withdrawing groups sharply increases the triboelectricity between the toner particles.

EXAMPLES The present invention will be explained in more detail with reference to Examples below.

Example 1 Copolymer consisting of the copolymerization components shown in Table 1 (weight average molecular weight: approx. /4 (10,000 to 150,000) 60% 31 yen, magnetite (manufactured by Toda Kogyo Co., Ltd., "EPT/000") 37% by weight and carbon black (manufactured by Mitsubishi Chemical Industries, Ltd., “#
After dry mixing 3% by weight of 30''), cross-mixing was carried out using a Ni-Goo.Next, this mixed substance was cooled and solidified, and then pulverized using a pulverizer, and then magnetic toner having a particle size of 1o-20μ was further mixed using an air classifier. Obtained.

Using the 4T magnetic toner, development was carried out using a commercially available electrophotographic copying machine using zinc oxide as a photoreceptor, using a magnetic film 1+ air brush development method, and the resulting copy was developed using a commercially available electrophotographic copying machine using zinc oxide. The image evaluation of the magnetic toner was performed by measuring the hardness of the non-image area (ground) using a reflection densitometer. The results are shown in Table 1.

Table 1 This is an example of developing a negative latent image on the actual flow side Fi, a zinc oxide photoreceptor. Therefore, is toner correct? #F The easier it is to conduct electricity, the higher the image density is expected to be.

However, as is clear from Table 1, Toner A, which uses a resin that also has electron-withdrawing groups, is actually more positively charged than Toner 16, which uses a resin that only has electron-donating groups, and which is the most positively charged. , 2 to A7 give higher image density.

Example 1 A magnetic toner was obtained in the same manner as in Example 1 except that the copolymers shown in the table below (weight average molecular weight: about /f - 130,000) were used as resins.

Using the obtained 7c magnetic toner, development was carried out by a magnetic brush development method in a commercially available electrophotographic copying machine using selenium as a photoreceptor, and image evaluation was performed in the same manner as in Example 1. The results are shown in Table.

This example is an example of developing a positive latent image on a selenium photoreceptor. Therefore, toner that is more likely to be negatively charged is expected to have a higher image density.

However, as is clear from the table, in reality, even the toner JftAt, which uses a resin that only has electron-withdrawing groups and is most likely to be negatively charged, the toner At~ which uses a resin that also has electron-donating groups. It can be seen that Jf6/ri gives a higher image density.

Example J In Example J, a magnetic toner was prepared in the same manner as in Example 1, except that the copolymers shown in Table 3 below (weight average molecular weight: approximately 10,000 to 1,000) were used as resins. It was.

Using the obtained magnetic toner, development was carried out by a magnetic brush development method in a commercially available electrophotographic copying machine using an organic photoconductor as a photoreceptor, and image evaluation was performed in the same manner as in Example. The results are shown in Table 3.

Table 3: Both f! It can be seen that it gives the concentration.

In Examples 1 and 2, #1, in which a mixture of the polymers shown in Table 1 (M weight average molecular weight: approximately /4e0,000 to /!0000) was used as the copolymer, was similarly magnetic. After obtaining the toner, image evaluation was performed in the same manner as in Example. The results are shown in Table DA.

A polymer mixture '4r containing a Z polymer having 4 groups and a polymer having an electron-withdrawing group as seen from the table.
- It can be seen that the magnetic toner used gives good image density.

Claims (1)

[Claims] (1) A magnetic toner comprising at least magnetic powder and a resin, wherein the resin has four electron groups and an electron-attracting group.