JPS59200254A - Magnetic toner - Google Patents

Abstract

PURPOSE:To improve dispersibility and to increase bonding strength to a resin by incorporating the magnetic powder coated with the resultant product of reaction between a silane coupling agent having an amino group and specific compd. having a group reactive with said amino acid in a toner. CONSTITUTION:The magnetic powder having, as its coating layer, the resultant product of reaction between a silane coupling agent having an amino group and 1 or >=2 kinds of compds. among ( I ) a compd. contg. a carboxyl group having 100mol.wt., (II) an acid anhydride having >=100mol.wt., (III) an isocyanate compd. having >=100mol.wt., and (IV) a ketene dye, etc. having 12-52 carbon atoms having a functional group reactive with said amino group is incorporated in a toner. A magnetic toner is prepd. by using such magnetic powder and using, for example, a methyl methacrylate/styrene copolymer, etc. as a binder resin, by which the excellent dispersibility of the magnetic powder is obtd. and the good bonding strength between the magnetic powder and the resin or wax is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic toner used to develop an electrical latent image or a magnetic latent image in electrophotography, electrostatic printing, or the like. As a law, for example, the Journal of the Image Electronics Engineers of Japan (published in 1976, Volume 5, No. 4, 17
Although a number of methods are known, such as those described on page 5), in general, a pixel latent image is formed on a photoreceptor using a photoconductive substance by various means, and then The latent image is developed using toner, and if necessary, a powder image made of toner is transferred to a transfer material such as paper, and then fixed by heat, pressure, solvent vapor, etc. to obtain a copy. It is something.

The developer is a two-component toner developer consisting of a toner in which dyes or pigments are dispersed in synthetic resin, wax, or natural resin, and a carrier of Eigen iron or ferrite granules; There is a one-component toner developer consisting of a magnetic toner in which magnetic powder such as magnetite is dispersed.

One-component development method does not use a carrier in the developer, so
It is not necessary to adjust the heating ratio of the carrier and toner, and there is no need for a stirring operation to mix the carrier and toner sufficiently uniformly, so it has the advantage that the entire developing device can be configured simply and compactly. have

Furthermore, there is no problem such as deterioration of developed image quality due to deterioration of the carrier over time.
It is necessary to uniformly disperse it in a resin or wax having a small surface energy, and it is not easy to uniformly disperse it because magnetic powder has poor affinity with such resins. Therefore, the process of kneading both takes a long time,
Attempts have been made to achieve uniform dispersion using mixers with high crosstalk energy, but magnetic powder is still often unevenly distributed. In addition, even if the magnetic powder is dispersed uniformly, the adhesive energy between the two is small, so the magnetic powder may be separated from the toner when the heated mixture is crushed to form a toner, or when the toner is actually used in a copying machine. Sometimes. This free magnetic powder may damage the photoreceptor or have an unfavorable effect on the characteristics of the photoreceptor, making it impossible to obtain stable images.

Various methods have been considered to overcome these drawbacks regarding magnetic toners. For example, melting point 40-200℃
By coating the surface of magnetic powder with an aliphatic compound,
An attempt was made to improve the physical and chemical stability of the toner (Japanese Patent Laid-Open No. 5O-139745), and by coating the surface of magnetic powder with acrylic resin or styrene resin, the transfer efficiency decreased in a high humidity atmosphere. An attempt was made to prevent this by dispersing magnetic powder treated with a reactive silane compound in a copolymerizable monomer (Japanese Unexamined Patent Publication No. 54-130J30). An attempt was made to increase the dispersibility of magnetic powder in resin by polymerizing it by 7i turbidity polymerization, and to further prevent the magnetic powder from being released from toner (Japanese Patent Laid-Open No. 58-764).
6) etc. have been proposed. However, even with such attempts, it is still difficult to easily and uniformly disperse magnetic powder such as magnetite into resin or wax, and there are also problems in terms of bonding strength between magnetic powder and resin or wax. It is difficult to say that the present inventors
In view of the above-mentioned current situation regarding magnetic toners, as a result of further intensive research, it was found that when magnetic powder is de-centered with a reaction product of a silane coupling agent having an amine group and a compound that can react with the amine group, the dispersion of the magnetic powder can be improved. The present inventors have discovered that it is possible to obtain a magnetic toner that has excellent properties and a high bonding strength between magnetic powder and resin or wax, and has completed the present invention.

That is, the present invention provides a silane coupling agent having an amine group and a silane coupling agent having a functional group capable of reacting with the amine group (
The present invention provides a magnetic toner containing magnetic powder having a layer covered with a reaction product with one or more compounds selected from the group consisting of I) to (5) (r) Molecular weight Compound containing a carboxyl group of 100 or more (IT) Acid anhydride (2) with a molecular weight of 100 or more Incyanate compound with a molecular weight of 100 or more ■ C12 or more
Examples of the silane coupling agent having an amine group that can be used in the present invention include H
2N C2H, NHO H65i (OCH, l, , H
2NC! 2H, 1tTHO, H65ifOH, 1(OO
H, 12°H2NC, H65ifOC! ,,H91,,
H2N0ONHC! , H65i (002H9l, .

can.

The compounds (I) to (2) above according to the present invention are not particularly limited as long as they are other than compounds that do not substantially react with the silane coupling agent having an amino group due to steric hindrance, etc. The compound groups and specific compound names are illustrated below (however, for isocyanate compounds, only specific compound names are illustrated).

(■) Carboxyl group-containing compounds with a molecular weight of 100 or more> 0 Higher fatty acids having 8 to 22 carbon atoms 0 Homopolymers or copolymers consisting of α,β-unsaturated carboxylic acids 0 α,β-unsaturated carboxylic acids Containing copolymers (specific compound names): lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, polyacrylic acid, polymethacrylic acid,
Polymaleic acid, copolymer of acrylic acid and tomaleic acid, copolymer of maleic acid and α-olefin, copolymer of methacrylic acid and styrene, etc. 0 Polymer consisting of maleic anhydride 0 Specific compound names such as copolymers containing maleic anhydride) Octadecanyl succinic anhydride, dodecenyl succinic anhydride, polymaleic anhydride, copolymer of maleic anhydride and methacrylic acid, maleic anhydride Copolymers of acids and α-olefins, etc.

(To) Incyanate compounds with a molecular weight of 100 or more (Specific compound name) The terminal of the molecule derived from diphenylmethane diisocyanate, tolylene diisocyanate, hexamethine/diisocyanate, polytetramethylene glycol and diphenylmethane diincyanate is an incyanate group. A certain compound, a compound whose molecular terminal is an isocyanate group derived from 1 mol of an ester obtained from 1,4-butanediol and adipic acid and whose molecular terminal is an isocyanate group derived from 2 moles of rutotolylene diisocyanate, trimethyl-proha71 A compound having 6 isocyanate groups derived from 1 mole of pentaerythritol and 6 moles of tolylene diincyanate, a compound having 4 incyanato groups derived from 1 mole of pentaerythritol and 4 moles of tolylene diincyanate, etc.

■ Ketene dimer with 12 to 52 carbon atoms
7 Compound Group> A ketene dimer represented by the following formula: R,-(1'-0,,=01H (in the formula, R and R2 each represent a hydrocarbon group having 4 to 24 carbon atoms).

Specific compound names) Octyl ketene dimer, octadecyl ketene dimer, eicosyl ketene dimer, octenyl ketene dimer, octadecenyl ketene/dimer, dodecyl phenyl ketene/dimer, etc.

In the present invention, the method for obtaining the magnetic powder coated with the reaction product of the silica/coupling agent having an amine group and the compound selected from (I) to (E) above is not particularly limited, and for example, the method is as follows. An example of a method for showing this is given below.

b) First heat-treat the magnetic powder (1) with the amino group-containing silane coupling agent (11) in an inert organic solvent, and then apply one or more selected from the group consisting of (I) to (ii) above. A method of heat treating compound (iii).

(1) and (11) and (fi) in an inert organic solvent.
t) is mixed all at once and heat treated.

C] First, in an inert organic solvent, the above (11) and (iiD
A method in which (1) is reacted, and then (1) is added and heat treated.

The amount of the amine group-containing silane cupping agent according to the present invention used is approximately 0.1 to 5 parts by weight, preferably 0.5 to 1.5 parts by weight, based on the magnetic powder. Also,
1 or 2 ponds selected from the group consisting of (r) to (5) above
The appropriate amount of the compound or more to be used is 2 to 4 times as much (based on the amount of M) as the silane coupling agent having an amine group.

Examples of inert solvents that can be used in the treatment of magnetic powder include benzene, toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, diethyl ketone, and cyclohexanone. The amount of the solvent to be used is not particularly limited, and may be adjusted so that the viscosity when the reactants are charged is appropriate.

As the magnetic powder that can be used in the magnetic toner of the present invention, all magnetic materials conventionally used in magnetic toners can be used, such as magnetite, ferrite, iron, and nickel.

Examples include powders such as cobalt.

In the present invention, a silane coupling agent having an amino group and the above-mentioned (
It is important to coat the magnetic powder with a reaction product with a compound selected from the group consisting of It is not possible to obtain a magnetic toner that is

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples. In addition,
All parts in Examples and Comparative Examples refer to M foot parts.

Example 1 100 parts of magnetite (EPT-500 manufactured by Toda Kogyo), 600 parts of toluene, and a silane coupling agent H21. H651 (002H9)
.

Take 1 part of and 3 parts of stearic acid, stir at 80°C for 2 hours, then wash the magnetite with a large amount of toluene,
It was then dried.

Production of magnetic toner■) 55 parts of surface-coated magnetite obtained by the above method and 45 parts of bisphenol-based polyester resin (Nutrack 382A manufactured by Kao Soap Co., Ltd.) were mixed, and the wet metal material was twin-screw extruded. The mixture was kneaded once in a gentle and loose manner, then coarsely pulverized with a pulverizer (registered trademark name: Pulverizer) manufactured by Honkawa Micron Co., Ltd., and further finely pulverized with an air jet mill. The finely pulverized material was spheroidized with hot air at 230°C, classified using a cyclone, and the average particle size was 12 to 13μ.
A magnetic toner of m was obtained.

Manufacture of magnetic toner ■〉 60 parts of the above surface-coated magnetite and one point at 108℃
A magnetic toner [1] having an average particle size of 12 to 16 .mu.m was obtained by mixing 40 parts of polyethylene wax with 40 parts of polyethylene wax and applying the method described in Magnetic Toner Production (1).

80 parts of the above-mentioned surface-coated magnetite and methyl methacrylate + MMA + /styrene fStl copolymer (copolymerization molar ratio MMA/S t = 511,150, molecular weight 20,000) were mixed, and the magnetic toner production described in ■ A finely ground product was obtained by the method described above. The finely ground material was spheroidized with hot air at 250°C, and classified using a cyclone to give an average particle size of 25μ.
A magnetic toner of m was obtained.

Evaluation of Dispersibility of Magnetic Powder> A certain amount of the magnetic toner obtained in the above-mentioned magnetic toner production (1) and (2) was separately placed on white paper, and the dispersion of the magnetic powder was observed under a microscope.

A state where no uneven distribution of magnetite can be confirmed is rated 5 (good dispersion), a state where uneven distribution of magnetite is clearly confirmed and the amount of uneven distribution is large is rated 1 (poor dispersion),
It was expressed as a numerical value from 1 to 6. The results are shown in Table-1.

Evaluation of Magnetic Powder 1; II Evaluation The magnetic toner obtained in the above-mentioned magnetic toner production ① was stirred for 8 hours in a magnetic brush unit for testing, and the release of magnetite Flj K from the magnetic toner was investigated. . The case where no magnetite was found to be liberated was rated 5 (good), and the case where almost all the magnetite was liberated was rated 1C (poor) and expressed as a value from 1 to 5. The results are shown in Table-1.

Example 2 Instead of stearic acid used in Example 1, maleic acid (
A surface-coated magnetite was obtained in the same manner as in Example 1, except that 3 parts of MA)/methacrylic acid (MEA) copolymer (copolymerization molar ratio MA/MEA=5o/so, molecular weight 950) was used. Next, five types of magnetic toners were produced using the surface nuclide magnetite according to the method of Example 1, and the dispersibility and release properties of the magnetite were evaluated using the same method as in Example 1. These results are shown in Table-
Shown in 1.

Example 6 Surface-nucleated magnetite was obtained in the same manner as in Example 1 except that 3 parts of dodecenylsuccinic anhydride was used in place of the stearic acid used in Example 1. Three types of magnetic toners were produced using the same method as in Example 1, and the dispersibility and release properties of magnetite were evaluated in the same manner as in Example 1.

These results are shown in Table-1.

Example 4 Instead of the stearic acid used in Example 1, Diacarna 60 (a copolymer of α-olefin, maleic anhydride, and phosphoric acid,
A surface-coated magnetite was obtained in the same manner as in Example 1, except that 3 parts of the compound (manufactured by Mitsubishi Kasei C Co., Ltd.) were used. Then,
Three types of magnetic toners were produced using the surface-coated magnetite according to the method of Example 1, and the dispersibility and release properties of magnetite were evaluated using the same method as in Example 1. Example 5 H2N was used instead of the silane coupling agent used in Example 1 as shown in Table 1.
The procedure was the same as in Example 1, except that 1 part of the silane coupling agent represented by o2H,NH(!, H65i(OOH,l, Then, the surface-coated magnetite was used to produce three types of magnetic toner according to the method of Example 1, and the magnetite was dispersed using the same method as Example 1. The properties and release properties were evaluated.The results are shown in Table-1.

Example 6 100 parts of Terracol 1000 (polytetramethylene glycol manufactured by DuPont, molecule i 1'000), and 4
．． 50 parts of 4'-diphenylmethane diisocyanate was reacted to produce a compound having an isocyanate group at the end of the molecule. Then, in place of the stearic acid used in Example 1, 4 parts of this incyanato group-containing compound was used to obtain surface-grained magnetite in the same manner as in Example 1. Next, three types of magnetic toners were produced using the surface aQ magnetite according to the method of Example 1,
The dispersibility and release properties of magnetite were evaluated by the same method as in Example 1. These results are shown in Table-1.

Example 7 Surface-coated magnetite was obtained in the same manner as in Example 1, except that 3.5 parts of octylketene dimer was used in place of the stearic acid used in Example 1. Three types of magnetic toners were produced using magnetite according to the method of Example 1, and the dispersibility and release properties of magnetite were evaluated using the same method as in Example 1. These results are shown in Table-1.

Comparative Example 1 Using the magnetite used in Example 1 as it is without any surface coating, six types of magnetic toners were manufactured according to the method of Example 1, and by the same method as Example 1,
The dispersibility and release properties of magnetite were evaluated. These results are shown in Table 1. Comparative Example 2 Silane was prepared in the same manner as in Example 1 using the magnetite and silane coupling agent used in Example 1. Then, using the surface-treated magnetite obtained to obtain magnetite whose surface was coated only with a coupling agent, three types of magnetic toners were manufactured according to the method of Example 1, and magnetite was The dispersibility and release properties were evaluated. These results are shown in Table 1.0 Comparative Example 3 In place of the stearic acid used in Example 1, methyl methacrylate (MMA)/styrene (St), a compound that does not react with the amino group-containing silane coupling agent, was used. The same procedure as in Example 1 was carried out, except that 3 parts of the polymer (copolymerization molar ratio MMA/St2 30/70, molecular weight 100,000) was used.
Magnetite surface coated with a silane coupling agent and the above copolymer. Next, three types of magnetic toners were produced using the surface-coated magnetite according to the method of Example 1, and the dispersibility and release properties of the magnetite were evaluated using the same method as in Example 1. These results are shown in Table-1.

Claims (1)

[Claims] A reaction between a silane coupling agent having an amino group and one or more compounds selected from the group consisting of (■) to (■) below having a functional group that can react with the amino group. Magnetic toner 0 (I) characterized by containing magnetic powder having a layer coated with a product. Carboxyl group-containing compound (n) having a molecular weight of 100 or more. Acid anhydride (down to) molecular weight 1 having a molecular weight of 100 or more.
Isocyanate compound with 00 or more carbon number 12. ~5
2 Stingy/Dimer