JPS59126545A - Manufacture of magnetic toner - Google Patents

Abstract

PURPOSE:To obtain a magnetic toner consisting of magnetic powder and an org. polymer united firmly to one body by polymerizing a vinyl monomer in a polymn. system contg. dispersed magnetic powder in the presence of a sulfonic acid or sulfonate monomer. CONSTITUTION:One or more kinds of radical polymerizable vinyl monomers are polymerized in a polymn. system contg. dispersed magnetic powder such as ferrite powder in the presence of a sulfonic acid or sulfonate monomer represented by formula I (where R1 is H, 1-20C alkyl, phenyl, a deriv. thereof or halogen; X is a group represented by formula II, III, IV or V; each of R2 and R3 is H or 1-15C alkyl; R4 is 1-15C alkylene; (m) is 1-20; (n) is 0-20; and Y is H, NH4 or an alkali metallic atom), e.g., 2-acrylamido-2-methylpropanesulfonic acid or sodium 2-methacrylethanesulfonate. A magnetic toner consisting of magnetic powder and an org. polymer united firmly to one body is manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic toner used for developing an electrostatic latent image formed in electrophotography or electrostatic recording, and a method for producing the same.

As is generally known, electrophotography is a photographic method that uses photoconductive substances, and reduces or eliminates static charges on a charged developing object using light or other various means. 2) This latent image is made visible using a developer such as a toner. 2 The toner is transferred to a transfer material such as paper or polymer film, and then heated, solvent, or applied. This is a method of obtaining copies by fixing using pressure or the like.

By the way, the toners used in these developing methods are divided into two-component toners and one-component toners. Two-component toners are used together with a carrier, while one-component toners contain magnetic powder themselves. This is extremely advantageous because it is not subject to changes over time such as changes in toner concentration in the developer.

On the other hand, in the production of the above-mentioned magnetic toner, conventionally magnetic powder, resin, and if necessary, a solvent and a dispersant are used.

After adding auxiliary agents such as pigments, they are mixed uniformly using a tumbler mixer, bow mill, etc., and the composition is dispersed and shaped into magnetic powder using a thermal mixer such as a heated roll, kneader, or extruder. The resulting magnetic powder-resin composite is pulverized using a high-performance pulverizer such as a jet mill, and then classified into two to obtain a magnetic toner.

However, in conventional magnetic toners, the properties of magnetic powder and resin as composite materials are significantly different from each other, resulting in poor interfacial compatibility such as compatibility and adhesion, and when melting and mixing, magnetic powder and resin are uniformly mixed. Because it is difficult to disperse, the component composition of the magnetic toner becomes non-uniform, and the resulting magnetic powder-resin composite becomes mechanically fragile, resulting in the generation of a large amount of fine toner particles with a particle size of 1 μm or less during the pulverization and classification steps. 2. This results in deterioration of the working environment and deterioration of toner quality.

Further pulverization exposes magnetic powder aggregates on the toner surface.

This method has various drawbacks such as a decrease in the resistance of the magnetic toner.

In view of the above-mentioned current situation, as a result of intensive studies, the present inventors have provided a magnetic toner and a method for producing the same, which have significantly improved dispersibility of magnetic powder and improved mechanical and electrical properties, which cannot be obtained by conventional methods. It is something to do.

That is, the present invention relates to the following general formula [I]R.

H2C=C-X-8o, Y... [l](
In the formula, R is an alkyl group having 1 to 20 H2 carbon atoms.

Phenyl group and its derivatives or halogen atom.

2 X is C0NH, C0NH-C-R,,Coo(CH,)
m.

3 or (CH,)n, IRNpRm is H or an alkyl group having 1 to 15 carbon atoms, and R4 is an alkyl group having 1 to 15 carbon atoms, respectively.
The alkylene group 9m of 15 is a sulfonic acid monomer represented by xi of 1 to 20, n is an integer of 0 to 20, and Y is H, Nl (or represents an alkali metal atom), or 7L has/l/
A magnetic powder and an organic polymer characterized in that at least one radically polymerizable vinyl monomer is polymerized in the presence of a phonate monomer in a polymerization system in which magnetic powder is dispersed. The present invention provides a method for producing a strongly integrated magnetic toner.

In general, when monomerization of monovinyl monomers is simply carried out in the presence of an acid under temperature conditions that do not cause thermal reaction, the polymerization rate remains low even after several days of polymerization time. On the other hand, according to the present invention, by adding magnetic powder as a third component, a very specific polymerization activity is brought about, and a polymer with a high polymerization rate of practical value can be produced in a few hours. In addition, it provides an extremely clean polymerization form without current generation due to gas phase polymerization.

Furthermore, the present invention is characterized in that the interaction between the surface of the magnetic powder and the polymer formed by the method of the present invention exceeds simple adhesion in the sense of adhesion. The polymer has a significantly high molecular weight. In other words, when compositing magnetic powder with a material 2 with a significantly different modulus of elasticity, such as a normal thermoplastic resin, the presence of a high molecular weight polymer with a modulus of elasticity intermediate to that of the image material at the interface facilitates stress transmission. Training,
Provides a magnetic toner that exhibits excellent mechanical properties.

To give an example of an embodiment for carrying out the present invention, an organic vinyl monomer and magnetic powder are suspended and dispersed in an aqueous medium under temperature conditions that do not cause a thermal polymerization reaction, and then sulfonic acid The monomer matrix t,- causes an aqueous independent polymerization reaction by adding and stirring a sulfonate monomer, and uniformly coats the vinyl monomer on the surface of the magnetic powder at a high polymerization rate over a predetermined polymerization time. It can be firmly fixed.

At this time, it is an essential condition that the three components mentioned above are brought into contact while coexisting, but it is not necessarily necessary to bring them into contact at the same time.

That is, 9 For example, even if a magnetic powder pretreated with a sulfonic acid monomer is used for the sulfonic acid monomer f1, a new sulfonic acid monomer or sulfonic acid salt will be added during the polymerization of the seven polymers according to the method of the present invention. Similar magnetic toners can be obtained without adding monomers.

Conventionally, a method for obtaining a similar polymer composition in the presence of hydrogen sulfite ions is known, but since a large amount of current from gas phase polymerization adheres and the product is extremely fine particles, it requires washing, 2 collection, etc. It has a fatal drawback regarding industrial Amagawa properties that post-processing is not easy. On the other hand, the method of the present invention uses a specific sulfonic acid monomer or sulfonate monomer, thereby resulting in a clean polymerization form with almost no current formation, and more surprisingly, the resulting magnetic powder-X coalescence Since the composition has excellent secondary flocculation performance, it provides a method for obtaining a product with extremely easy post-processes such as washing and recovery.

Certain sulfonic acid or sulfonate monomers used in the present invention have sulfonic acid groups as active sites that provide N6 activity.

In addition, the presence of double bonds as active sites is essential for developing strong bonding properties between the produced polymer and the magnetic powder. Any compound having a structural formula containing these functional groups can be used as the sulfonate monomer or sulfonate monomer of the present invention, but specifically, 2-acryla, ')--2-methylpropane sulfonate, yv<more.

AMPS), sodium 2-methacrylethanesulfonate (hereinafter abbreviated as SEM-Na)
, 3-methacrylicpropa/sodium sulfonate (hereinafter abbreviated as sps), sodium 2-glopenesulfonate (hereinafter abbreviated as N a S ), 2-mef
Sodium Ru-2-propenesulfone (hereinafter referred to as NaM
S (abbreviated as j), etc., and A containing 2% amide bond
MPS, SEM-Na and s containing ester bonds
It is preferable because it exhibits remarkable secondary aggregation performance such as PS and has extremely high polymerization activity.

Magnetic powder used in the present invention includes magnetite,
Ferrite, iron, chromium, manganese and their alloys and compounds, triiron tetroxide.

Ferromagnetic powder of iron sesquioxide, cobalt-γ-ferromagnetic oxide powder of chromium oxide (cahinyl%/-r-0) activation and strong coalescence effect with the polymer are particularly remarkable. preferable.

The vinyl monomer used in the present invention includes:

Although all vinyl monomers that can be radically polymerized are used, methyl methacrylate has a particularly high polymerization activity and has good compatibility between the produced polymer and the magnetic powder. When using a mixture of two or more monomers, methyl methacrylate is one of the components and is particularly preferred.
According to the present invention, the concentration of the sulfonic acid monomer or the sulfonate monomer is about 0,000,000 or less based on the total weight of the magnetic powder and the monomer. 05-1001 amount, preferably 0.1-5
It is used in an amount of 0% by weight, particularly preferably from 0.5 to 3% by weight. In most cases, it is preferred to increase the amount of sulfonic acid or sulfonate monomer as the monomer component increases. The ratio of M of the monomer or monomer mixture to the magnetic powder used can be varied over a wide range and range from about 500:1 to 1:5. Preferably about 50:1
1 to about 1=1. The amount of water is about 1% to several hundred times, preferably about 10%, based on the total M amount of magnetic powder and monomer.
~10 times. The reaction is preferably carried out at a temperature of about 10 to 100°C, under an atmosphere of an inert gas, such as nitrogen, for example.
Preferably it is carried out at 20 to 80°C. The specific reaction temperature here is selected as appropriate depending on the vinyl monomer used, but it is necessary to conduct the reaction at a temperature at which thermal polymerization is suppressed to a negligible extent, and at a high temperature at which thermal polymerization occurs extremely. In this case, the compatibility and uniformity of the resulting magnetic powder-resin composite are impaired. Reaction time is 30 minutes to about 15 hours. The temperature of the generated magnetic powder-resin composite is approximately 10 to 3.00°C.
, preferably at a temperature range of about 50 to 200°C. Note that the interaction between the surface of the magnetic powder and the electrolyte formed by the method of the present invention goes beyond adhesion in a physical sense due to simple adsorption or van der Waals forces.

This fact is clear from the fact that a large amount of unextracted polymer is observed even when the vinyl polymer is extracted with a good solvent.

Since the magnetic powder-resin composite obtained by the present invention has a high polymer content, it can meet the required performance as a magnetic toner by itself, but in some cases, it may be used by heat kneading with a thermoplastic resin. You can also do it. Examples of the thermoplastic resin to be kneaded include acrylic resin, polyester resin, polyamide resin, polyethylene resin, polystyrene resin, and polyvinyl chloride resin.

EBOKI 7 resin, polyvinyl acetate, vinyl resin, polyvinylpyrrolidone resin, polyvinyl alcohol resin.

Cellulose polyacetate resin, poly-N-vinyl carba/
Examples thereof include polyvinyl resin, silicone resin, polyvinyl acetate resin, vinyl butyral resin, melamine resin, and copolymers thereof.

As the thermal mixing means in the method of the present invention, methods using commonly used mixing machines such as heated rolls, kneaders, mixers, screw extruders, etc. can be employed.

The magnetic powder-resin composite obtained by the present invention or the kneaded product after thermal kneading with a thermoplastic resin is processed by a conventionally known pulverization and two-classification method to obtain a magnetic toner.

In the method of the present invention, if necessary, in the presence of magnetic powder,
At some point during the reaction of vinyl monomers with specific sulfonic acid monomers and sulfonate monomers or during the thermal kneading of the resulting magnetic powder-resin composite and thermoplastic resin, carbon black, hytetane diacid, valve Coloring agents such as pigments for patterns, azo dyes, phthalocyanine dyes, etc. may be blended t7.

In the magnetic toner according to the present invention, the surface of the magnetic powder is not only simply coated with vinyl monomer, but also in a strongly unified state that goes beyond adhesion in the sense of simple adsorption. .

It has excellent electrical properties showing high insulating properties, has extremely good compatibility with resin, significantly improves the dispersibility of magnetic powder, and has a strong bond with resin, making it mechanically stable even when the magnetic powder content is increased. It has various excellent properties such as no decrease in strength.

Next, the present invention will be explained in more detail with reference to Examples.

Example 1. Comparative Examples 1 to 6 In a 500 ml four-bottle flask equipped with a cooling tube, a nitrogen introduction tube, a stirring rod, and a thermocouple for detecting internal temperature, 38.7 J' of magneta and ion fine powder as magnetic powder were added to 270 g of deionized water.
The mixture was suspended and dispersed in m1, and the mixture was replaced with nitrogen for 30 minutes. Next, methyl methacrylate 30 was used as a vinyl monomer.
．． 07' was added with vigorous stirring under a stream of nitrogen.

Next, the temperature of the reaction solution was raised to 50° C. in a hot water bath, and a uniform dispersion state of the added monomer was confirmed.

SEM-Na as sulfonate monomer 6.
A solution of 5J' dissolved in 10 ynl of deionized water was gradually added, and a polymerization reaction was carried out at the same temperature for 8 hours. After the polymerization was completed, about 2 samples were taken from the 2 reaction solutions.

The amount of remaining unreacted monomer was determined by gas chromatography using dioxane as an internal standard reagent to determine the polymerization rate.

For comparison, when no magnetic powder is added, when no sulfonic acid monomer or sulfo/acid monomer is added,
The polymerization behavior when ethanesulfonic acid, which is a saturated organic sulfonic acid, was added and when sulfurous acid water was added were also investigated by performing the same polymerization operation and evaluation after the first reaction.

The results are shown in Table 1. All two parts indicate the vehicle quantity part.

*1 6-chi H2S03 aqueous solution
*4 *2 BL-500 manufactured by Titan Kogyo Co., Ltd. *3 MMA: Methyl methacrylate ox current adhesion ◎ ... Almost no.

×...It sticks quite a bit.

XX... A large amount adheres.

Secondary aggregation property ◎... Good, and cleaning and recovery are very easy.

XX... It is defective, and cleaning and recovery are extremely difficult.

As is clear from Table 1, the system shown in Comparative Example 4 without the addition of sulfonic acid monomer or sulfonate monomer shows no polymerization activity, and the combination of sulfonic acid monomer or sulfonate monomer and vinyl monomer shows no polymerization activity. Whereas a simple two-component system has extremely low polymerization activity, the method of the present invention in which magnetic powder is added as a third component significantly increases the monomer polymerization rate. Although the monomer polymerization rate is high, the polymerization conditions such as current adhesion and secondary aggregation performance are significantly inferior to the method of the present invention.2 The method of the present invention shows that the practicality is dramatically improved. There is.

Further, as determined by weight measurement after drying, the polymer content in the magnetic powder-resin composite produced by the method of the present invention was 37%.

Examples 2 to 5 In Example 1, SPS, AM and SEM-Na Kashi9 were used as the sulfonic acid monomer and Matahas sulfonate monomer.
Polymerization was carried out in the same manner as in Example 1 except that PS, NaAS, and NaMS were used, and the monomer 1 ratio was measured and evaluated. The results were compared with Example 1 and are shown in Table 2.

Table 2 As is clear from Table 2, the monopolymerization activity is SEM・Na, S
NaAS has extremely high PS and AMP S.

Na M S showed a slightly low level.

Polymer composition obtained by the method of Examples 1 to 5 about 1
Weighed 0P together with a cylindrical opening paper, and performed a 24-hour Soxhlet extraction test using benzene, which is a good solvent for methyl methacrylate polymer, as an extraction solvent. [η] was measured. For comparison, a composition coated with polymethyl methacrylate prepared by dispersing magnetic powder (magnetite fine powder) in a methichloride solution of polymethyl methacrylate and then evaporating the solvent was prepared (Comparative Example 7). and a composition produced using a normal radical polymerization medium (Table 3 shows the O-bonds that were evaluated and examined in the same way for Comparative Examples 8 and 9. was completely extracted in the extraction test between 24 samurai, whereas the extraction rate of the polymer component of the composite obtained by the method of the present invention is small, and the fraction is not extracted and is strongly combined with magnetite. Furthermore, it can be seen that the polymer has a significantly higher temperature [η] than the polymer obtained by the conventional method.

3rd surface extraction and mixing)) )) 〉X *1...Magnetic powder uses magnetite fine powder *2...25℃, 0.5% chloroform solution Measured value *3: Mitsubishi Rayon Co., Ltd., Acrybella) (VH
) Used AIBN: Azobisisobutyronitrile KPS: Potassium persulfate Example 6 Styrene-acrylonitrile was added to a composition in which the monopolymer obtained by the method of Examples 1 to 5 was coated and unified on the surface of magnetic powder. Add the polymer in the same proportion as the magnetic powder,
After mixing and heat kneading in a single-screw extruder, the mixture was crushed and classified into two parts to obtain a magnetic toner having a particle size of 10 μm.

Comparative Example 10 Using the compositions obtained by the methods of Comparative Examples 7 to 9, a mixed wire similar to Example 6 was prepared.

In the cross-wire operation process, it was very difficult to mix the composition into the resin, and the state of dispersion of the magnetic powder was extremely non-uniform. Next, the mixed wire material was crushed and classified into two parts, but a large amount of over-pulverized particles were generated, and the workability was significantly worse than in Example 6.

Next, the magnetic toners of Example 6 and Comparative Example 10 were electrostatically coated on a stainless steel plate, and the surface potential decay rate of the coated layer was measured. In contrast, all nine magnetic toners of Comparative Example 10 exhibited a fast decay rate of 65%/hour or more.

Example 7 The reaction was carried out in the same manner as in Example 1 except that the type of magnetic powder was changed, and the results of evaluating the obtained composition are shown in Table 4.

Table 4 As is clear from Table 4, in the method of the present invention, almost no magnetic powder selectivity with respect to 1-polymerization activity was observed, the monomer polymerization rate was generally good, and the polymer content in the produced composite was The ratio also showed a high level. Furthermore, the surface potential decay rate of 1 m of coating electrostatically coated by the above method was 10%/hour or less in all cases.

Example 8 In place of methyl methacrylate as the vinyl monomer,
The same procedure as in Example 1 was carried out except that 1 m of the vinyl monomers shown in the table or a mixture of the two types were used, and the results of evaluating the obtained composition are shown in Table 5. ...The charging weight ratio of the mixed system is 5015QST: styrene, /BuA n-butyl acrylate, /M
MA: Methyl methacrylate Example 9 In a Henschel mixer for powder kneading, magnetite 38
．． Add 7P and SEM-Na 6.5P.

After stirring thoroughly for 10 minutes, using a reactor set in the same manner as in Example 1, the entire amount of the magnetic powder subjected to the above treatment was suspended in 280 ml of deionized water.

The mixture was dispersed and replaced with nitrogen for 30 minutes. Next, methyl methacrylate 30, OJ' was added as a vinyl monomer with vigorous stirring under nitrogen flow. Next, the temperature of the reaction solution was raised to 50° C. in a hot water bath, and a polymerization reaction was carried out at the same temperature for 8 hours. After the polymerization was completed, the same evaluation as in Example 1 revealed that the monomer polymerization rate was 73.0%, and the obtained composite had a magnetic powder surface uniformly covered with the polymer of the vinyl monomer. It was a strongly fixed composition.

The composition was made into a toner and electrostatically coated in the same manner as in Example 6, and the surface potential decay rate of the coating layer was 9%/hour.

Claims (1)

[Claims] 1. The following general formula [Ia 1 H2C=C-X-8o, Y... [Ia(
In the formula, R1 is H9 an alkyl group having 1 to 20 carbon atoms. Ferrous group and its derivatives or...loge/atom. R. 3 or (CH2)n, where HR,, R:l is H or an alkyl group having 1 to 15 carbon atoms, and R4 is an alkyl group having 1 to 1 carbon atoms.
5's alkylene y group 2m is an integer of 1 to 20, n is 0 to 20
in the presence of a sulfo/acid monomer or a sulfonate monomer represented by (integer number of Y represents H, NH, or an alkali metal atom), and in a polymerization system in which magnetic powder is dispersed, at least one kind of A method for producing a magnetic toner in which a magnetic powder and an organic polymer are strongly integrated, characterized by polymerizing a radically polymerizable vinyl monomer. 2. The sulfonic acid monomer or sulfonate monomer is 2-acrylamido-2-methylpropanesulfonic acid, sodium 2-methacrylethanesulfonate or sodium 3-methacrylpropanesulfonate, according to claim 1. Method of manufacturing magnetic toner. 3. The method for producing a magnetic toner according to claim 1 or 2, wherein the main component of the vinyl monomer is methyl methacrylate. 4. Magnetic powder is magnetite, ferrite, cobalt,
A patent claim of at least one type of ferromagnetic powder selected from chromium, manganese, alloys and compounds thereof, triiron tetroxide, iron sesquioxide, cobalt-γ-iron sesquioxide powder, and chromium oxide powder. A method for producing a magnetic toner according to item 1, item 2, or item 3.