JP3407417B2 - Spherical composite particle powder and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spherical composite particle powder having a high strength, a large saturation magnetization value and an appropriate electric conductivity, and a method for producing the same.

The main uses of the spherical composite particle powder according to the present invention are materials for electrostatic latent image developers such as magnetic carriers and magnetic toners, materials for electromagnetic wave absorbers, materials for electromagnetic wave shields, brake shoes and polishing. Materials, Lubricating materials, Magnetic separation materials, Magnet materials, Ion conversion resin materials, Immobilized enzyme carrier materials, Display materials for displays, Damping materials, Paint materials, Coloring materials for rubber / plastics, Filling Materials, reinforcing materials, etc.

[0003]

2. Description of the Related Art In recent years, development of new products and development of new applications have been vigorous, and therefore research and development of materials having high performance and new functions are active.

In the various fields mentioned above, there are no exceptions, and various attempts have been made to combine different kinds of materials with each other and to combine different kinds of characteristics. A spherical composite having both a large saturation magnetization value and an appropriate conductivity. Body particle powders are currently strongly demanded.

Further, in order to sufficiently maintain and exhibit the various properties of the spherical composite particle powder during processing, treatment, use, etc., it is required that the spherical particles have a high strength, a high packing property and a high fluidity. Has been done.

Conventionally, metal particles such as iron and metal oxide powders such as ferrite have been known as particles having both properties of magnetism and conductivity.

As a method of imparting conductivity to various particles, a method of coating the surface of particles of metal particles, ceramic particles or plastic particles with metal by sputtering or CVD method (Japanese Patent Laid-Open No. 62-250172).
A method of coating a metal surface of a ceramic particle or a ceramic particle or a plastic particle with a metal by an electroless plating method (Japanese Patent Application Laid-Open No. HEI 6-242242)
3-18096).

[0008] Further, a method of applying mechanical impact to fix and fix resin particles to which carbon black is fixed onto the surface of magnetic particles (Japanese Patent Laid-Open No. 13969/1990), a composite of magnetic powder and binder resin There is a method of attaching conductive fine particles to the surface of particles.

[0009]

A spherical composite particle powder having high strength and having both a large saturation magnetization value and an appropriate conductivity is currently most demanded. By the known method, particles having such characteristics have not been obtained yet.

That is, the metal powder such as iron is difficult to fill at the time of use because its shape is indefinite.
Since it is not sufficiently dispersed in the vehicle, its function cannot be fully exerted, and it is easily oxidized, which makes it extremely difficult to handle. Some of the metal oxide powders such as the above-mentioned ferrite are spherical and stable in the air, but the conductivity is not sufficient.

In the case of the methods described in the above and the above, the conductive layer coated on the surface of the particles is easily peeled off due to mechanical shear, and the conductivity is lowered with time. In particular, the method (2) has a high treatment cost and requires a special device, and the method (3) has a problem of treating the plating waste liquid.

Also in the above-mentioned methods and the methods described above, the surface conductive layer coated on the surface of the particles is easily peeled off due to mechanical shear. The further method has a small saturation magnetization value because the content of magnetic particles is small.

Therefore, according to the present invention, spherical composite particle powder having a high strength, a large saturation magnetization value and an appropriate conductivity is obtained so that the conductive magnetic particles are not peeled or separated. This is a technical issue.

[0014]

The above technical problems can be achieved by the present invention as described below.

That is, the present invention provides a spherical composite particle comprising magnetic particle powder, a thermosetting resin, and carbon produced by carbonizing a part of the thermosetting resin.
Spherical composite particles consisting of spherical composite particles having an average particle diameter of 1 to 1000 μm and spherical particles having an average particle diameter of 1 to 1000 μm formed by binding magnetic particle powder with a thermosetting resin as a binder. It is a method for producing the spherical composite particle powder, which comprises heating the composite particles in an inert atmosphere at a temperature of 350 ° C. or higher to carbonize the thermosetting resin.

The structure of the present invention will be described in detail below.

First, the spherical composite particle powder according to the present invention will be described.

As the magnetic particle powder, magnetic iron oxides such as magnetite and gamma iron oxide, and metals other than iron (Mn, N
(i, Zn, Mg, Cu, etc.), magnetoplumbite type ferrites such as spinel ferrite, barium ferrite, etc., containing fine particles of iron or alloy having an oxide layer on the surface can be used. Its shape is
It may be granular, spherical or acicular. In particular, when high saturation magnetization is required, magnetic particle powder such as iron can be used, but considering chemical stability, spinel ferrite and barium ferrite containing magnetic iron oxide such as magnetite and gamma iron oxide, etc. It is preferable to use the magnetic particle powder of magnetoplumbite type ferrite.

The content of the magnetic particle powder is preferably 80 to 98% by weight. If it is less than 80% by weight, the saturation magnetization value tends to be insufficient, and if it exceeds 98% by weight,
The binding between the ferromagnetic particles is weak and the strength tends to be low. 80-95% by weight considering saturation magnetization and strength
Is preferred.

As the thermosetting resin according to the present invention, commonly used phenol resin, epoxy resin, melamine resin, urea resin, urethane resin and the like can be used. Considering the particle strength, a phenol resin or an epoxy resin is preferable.

The content of the thermosetting resin according to the present invention is 1
It is preferably 3% by weight or less. If it exceeds 13% by weight, the desired conductivity cannot be obtained. Considering the conductivity, it is preferably 10% by weight or less.

The carbon content in the present invention is 2 to 15% by weight based on the thermosetting resin. If it is less than 2% by weight, the conductivity tends to be insufficient and the strength of the particles tends to be small. If it exceeds 15% by weight, the saturation magnetization value tends to decrease. Considering the conductivity and the saturation magnetization value, 2 to 11% by weight is preferable.

The average particle size of the spherical composite particles according to the present invention is 1 to 1000 μm. Particles having an average particle diameter of less than 1 μm are likely to secondary agglomerate, and particles having an average particle diameter of more than 1000 μm are liable to have insufficient mechanical strength. The average particle size may be appropriately selected depending on each application. For example, as a developer such as a carrier and a toner, those having an average particle diameter of 1 to 300 μm, preferably 2 to 200 μm can be used.

The spherical composite particles according to the present invention have a substantially spherical shape. Therefore, it has excellent dispersibility and fluidity, and also has excellent mechanical strength.

In the present invention, spherical composite particles having a sphericity of 0.7 to 1.4 in the ratio of the minimum diameter l to the maximum diameter w can be obtained. The sphericity is preferably 0.8 to 1.3.
When the sphericity is less than 0.7 or exceeds 1.4, it is difficult to obtain composite particles having sufficient dispersibility and fluidity.

Next, a method for producing the spherical composite particle powder according to the present invention as described above will be described.

The spherical composite particles according to the present invention are spherical composite particles having an average particle size of 1 to 1000 μm formed by binding magnetic particle powder with a thermosetting resin as a binder in an inert atmosphere at a temperature of 350 ° C. or higher. It is obtained by carbonizing a part of the thermosetting resin by heat treatment with.

The spherical composite particles obtained by binding the magnetic particle powder with a phenol resin which is a thermosetting resin as a binder are obtained by mixing phenols and aldehydes in an aqueous medium in the presence of the magnetic particle powder and a basic catalyst. It can be produced by reacting and curing.

The spherical composite particles obtained by binding the magnetic particle powder with an epoxy resin, which is a thermosetting resin, as a binder reacts bisphenols with epihalohydrin in an alkaline aqueous medium in the presence of magnetic particles. In the case of curing or curing an uncured epoxy resin in an aqueous medium to produce a composite granular material composed of magnetic particles and a cured epoxy resin, the surface of the magnetic particles is subjected to a lipophilic treatment. It is obtained by using magnetic particles that are present.

First, the case where the former thermosetting resin is a phenol resin will be described.

The type of the magnetic particle powder in the present invention is as described above, and the particle diameter is preferably 0.01 to 10 μm, and the spherical composite particles are formed by dispersing the magnetic particle powder in the aqueous medium. Considering the strength of
It is preferably 0.05 to 5 μm.

It is desirable that the magnetic particles have been subjected to lipophilicity treatment in advance, and if magnetic particles that have not been subjected to lipophilicity treatment are used, it may be difficult to obtain spherical composite particles. is there.

The lipophilic treatment is carried out by a method of treating with a coupling agent such as a silane coupling agent or a titanate coupling agent, or by dispersing magnetic particles in an aqueous solvent containing a surfactant to obtain surface-active particles. There is a method of adsorbing the agent.

The silane coupling agents include those having a hydrophobic group, an amino group and an epoxy group, and the silane coupling agents having a hydrophobic group include vinyltrichlorosilane, vinyltriethoxysilane and vinyl.
There are tris (β-methoxy) silane and the like, and as titanate coupling agents, there are isopropyl triisostearoyl titanate, isopropyl tridodecylbenzenesulfonyl titanate, isopropyl tris (dioctyl pyrophosphate) titanate and the like.

As the silane coupling agent having an amino group, γ-aminopropyltriethoxysilane, N
Examples include -β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane and N-phenyl-γ-aminopropyltrimethoxysilane.

As the silane coupling agent having an epoxy group, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) trimethoxysilane, etc. There is.

As the surface active agent, commercially available surface active agents can be used, and those having a functional group capable of binding to a hydroxyl group present on the magnetic particles or the surface of the particles are desirable, and in terms of ionicity, a cationic group is used. Alternatively, anionic ones are preferable.

Although the object of the present invention can be achieved by any of the above-mentioned treatment methods, the treatment with a silane coupling agent having an amino group or an epoxy group is preferable in consideration of the adhesiveness with a phenol resin.

The amount of the magnetic particle powder is preferably 0.5 to 200 times the weight of the phenols, and more preferably 4 to 100 times the weight of the spherical composite particles produced.

As the basic catalyst, a basic catalyst used in the usual production of resole resins is used. Examples thereof include aqueous ammonia, hexamethylenetetramine, and alkylamines such as dimethylamine, diethyltriamine, and polyethyleneimine. The molar ratio of these basic catalysts to phenols is preferably 0.02 to 0.3.

As phenols, in addition to phenol,
m-cresol, p-tert-butylphenol, o
-Propylphenol, resorcinol, alkylphenols such as bisphenol A, and a compound having a phenolic hydroxyl group such as halogenated phenols in which a part or all of the benzene nucleus or the alkyl group is substituted with a chlorine atom or a bromine atom, Of these, phenol is the most preferable. When a compound other than phenol is used as the phenol, particles may be difficult to form, or even if particles are formed, the particles may have an irregular shape. Therefore, phenol is most preferable in consideration of the shape property.

Examples of aldehydes include formaldehyde and furfural in the form of either formalin or paraaldehyde, and formaldehyde is particularly preferable. The molar ratio of aldehydes to phenols is preferably 1-2, and particularly preferably 1.1-1.
It is 6. When the molar ratio of aldehydes to phenols is less than 1, particles are difficult to be generated, or even if they are generated, curing of the resin is difficult to proceed, so that the strength of the particles to be generated tends to be weak. If the molar ratio of aldehydes to phenols is greater than 2,
Unreacted aldehydes remaining in the aqueous medium after the reaction tend to increase.

The spherical composite particles are allowed to undergo a curing reaction at the same time as a reaction in the temperature range of 70 to 90 ° C. and then cooled to 40 ° C. or lower to obtain an aqueous dispersion containing the spherical composite particles.

Next, the aqueous dispersion is separated into solid and liquid by a conventional method such as filtration and centrifugation, and then washed and dried to obtain spherical composite particles.

In the reaction, a suspension stabilizer may be present if necessary.

Examples of the suspension stabilizer include hydrophilic organic compounds such as carboxymethyl cellulose and polyvinyl alcohol, fluorine compounds such as calcium fluoride, and water-insoluble inorganic salts such as calcium sulfate.

Next, the case where the latter thermosetting resin is an epoxy resin will be described.

The magnetic particles whose surface has been subjected to lipophilic treatment are
Either a method of simply mixing the magnetic particles and the lipophilic treatment agent, or a method of mixing the magnetic particles and the lipophilic treatment agent in an aqueous solvent to adsorb the lipophilic treatment agent on the particle surface It can also be obtained by the method of.

As the lipophilic treatment agent, a titanate-based or silane-based coupling agent having a lipophilic group, a silylating agent, a silicone oil or the like can be used.
In particular, those having a functional group reactive with the epoxy resin (-NH _2, Formula 1, etc.) are preferable because an effect of such increase the strength of the composite granules themselves.

[0050]

[Chemical 1]

Examples of titanate coupling agents having a lipophilic group include isopropyl triisostearoyl titanate, isopropyl tridodecylbenzenesulfonyl titanate, isopropyl tris (dioctyl pyrophosphate) titanate, bis (dioctyl pyrophosphate) oxyacetate titanate, bis ( Dioctylpyrophosphate) ethylene titanate and the like are silane coupling agents having a lipophilic group, such as N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-
β (aminoethyl) γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, N
-Phenyl-γ-aminopropyltrimethoxysilane,
γ-glycidoxypropylmethyldiethoxysilane, β
-(3,4 epoxycyclohexyl) ethyltrimethoxysilane (the above are silane coupling agents having a functional group capable of reacting with an epoxy resin), vinyltrichlorosilane, vinyltriethoxysilane, vinyltris (β-methoxy). Examples include ethoxy) silane, silylating agents such as hexamethyldisilazane, trialkylalkoxysilane and trimethylethoxysilane, and examples of silicone oils such as dimethyl silicone oil and methyl hydrogen silicone oil.

The treatment amount with the lipophilic treatment agent is 0.1 to 5.0% by weight based on the magnetic particles. If it is less than 0.1% by weight, the lipophilic treatment is insufficient, and it becomes difficult to obtain a composite granular material having a high content of magnetic particles. 5.
When it exceeds 0% by weight, the degree of lipophilicity is too large, and thus the adhesiveness of the produced composite granules increases and the composite granules agglomerate to form a large lump. Therefore, it becomes difficult to control the particle size of the composite granular material.

As the bisphenols, compounds having two or more phenolic hydrogen groups such as bisphenol A, bisphenol F, bisphenol S and resorcin can be used. Bisphenol A is preferable from the economical point of view.

The amount of bisphenols used is 0.5 to 25% by weight based on the magnetic particles. If it is less than 0.5% by weight, the amount of the epoxy resin produced is insufficient with respect to the magnetic particles, so that it becomes difficult to obtain composite particles. If it exceeds 25% by weight, the amount of the epoxy resin produced becomes excessive with respect to the magnetic particles, and it is not possible to obtain a composite granular material having a high content of magnetic particles. Also,
Aggregation of the composite granules easily occurs, and it becomes difficult to control the particle size of the composite granules.

As epihalohydrin, epichlorohydrin, epibromhydrin, epiiodohydrin and the like can be used, and epichlorohydrin is preferred.

The amount of epihalohydrin used is 0.3 to 20% by weight based on the magnetic particles. If it is less than 0.3% by weight, the amount of the epoxy resin produced becomes insufficient with respect to the magnetic particles, so that it becomes difficult to obtain composite particles. If it exceeds 20% by weight, the amount of the epoxy resin produced becomes excessive with respect to the magnetic particles, and it is not possible to obtain a composite granular material having a high content of magnetic particles. Also,
Aggregation of the composite granules easily occurs, and it becomes difficult to control the particle size of the composite granules.

The molar ratio of bisphenols to epihalohydrin is 0.5 to 1.0: 1.0.
If it is less than 0.5, it becomes difficult to granulate due to the influence of reaction by-products and the like caused by excess epihalohydrin.
If it exceeds 1.0, the curing rate will be high, and it will be difficult to obtain composite granules, and even if obtained, the spread of the particle size distribution will be large.

The alkaline aqueous medium can be obtained by adding an alkali such as sodium hydroxide or potassium hydroxide to water.

The reaction is carried out by heating an alkaline aqueous medium containing magnetic particles, bisphenols and epihalohydrin to a temperature in the range of 60 to 90 ° C. with stirring in the presence of a curing agent, and carrying out the polymerization reaction for about 1 to 5 hours. To proceed, or
While stirring in an aqueous medium containing magnetic particles and an uncured epoxy resin in the presence of a curing agent, the temperature is raised to a temperature in the range of 60 to 90 ° C. and the curing reaction is allowed to proceed for about 1 to 8 hours. Be done.

The curing agent is generally widely known as a curing agent for epoxy resins. For example, acid anhydrides and amines can be used.

As the uncured epoxy resin, epoxy compounds having two or more epoxy groups in the molecule such as bisphenol A glycidyl ether at both terminals and polyethylene glycol glycidyl ether at both terminals can be used.

The composite particles formed in the alkaline aqueous medium or in the aqueous medium may be subjected to solid-liquid separation by a usual method such as filtration and centrifugation, then washed with water and dried by heating.

The heat treatment of the spherical composite particles in the present invention is carried out at a temperature of 350 ° C. or higher in an inert atmosphere.

The heat treatment furnace may be either a fixed type or a rotary type, but a rotary type is preferable in order to prevent aggregation of particles.

As the inert atmosphere in the present invention, an inert gas such as helium, argon or nitrogen may be passed through the heat treatment furnace, and nitrogen gas is sufficient in terms of cost.

It is important that the flow rate of the inert gas is 1 l / min or more in order to prevent the oxidation that is a concern when using magnetic particle powder, particularly iron or magnetite.

The heating in the present invention may be carried out at a temperature required to decompose and carbonize a part of the phenol resin or epoxy resin, that is, 350 ° C. or higher. When the treatment temperature is lower than 350 ° C, carbonization of the resin is difficult to proceed and it takes a long time. If the temperature is 350 ° C or higher, the temperature is sufficient to carbonize a part of the phenol resin or epoxy resin, but a temperature that considers the degree of carbonization of the resin component and the decrease of the saturation magnetization value due to the composition change of the magnetic particle powder. ,
It is important to set the time. The upper limit value is preferably 450 ° C. in consideration of controlling the saturation magnetization value of the magnetic particle powder and the degree of carbonization of the resin component. 450 ° C
When the temperature is higher than 100 ° C., the electric conductivity becomes too high due to the complete carbonization of the resin component, and when the temperature is higher than 800 ° C., the reduction of the magnetic particle powder is facilitated by the resin. For example, in the case of magnetite, The reduction proceeds and part or all becomes wustite or iron, which are easily oxidized, and when oxidized, the saturation magnetization value decreases.

The heat treatment time varies depending on the heating temperature, but a treatment of 0.5 to 3 hours is sufficient.

[0069]

First, the most important point in the present invention is that spherical composite particles having an average particle diameter of 1 to 1000 μm formed by binding magnetic particle powder with a thermosetting resin as a binder are heated to 350 ° C. or more in an inert atmosphere. When a part of the thermosetting resin is carbonized by heat treatment at a temperature, from the magnetic particle powder, the thermosetting resin, and carbon generated by carbonizing a part of the thermosetting resin It is possible to obtain a spherical composite particle having an average particle diameter of 1 to 1000 μm, and the spherical composite particle has a high strength and a large saturation magnetization value and an appropriate conductivity. It is a fact of having.

The reason why the spherical composite particles according to the present invention have a large saturation magnetization value and an appropriate conductivity is that the resin constituting the spherical composite particles is a thermosetting resin having a high residual carbon rate. And the content of the magnetic particle powder contained in the spherical composite particles is as high as 80 to 98% by weight.

The reason why the spherical composite particles according to the present invention have high strength is that the magnetic particle powders are bonded uniformly and firmly by a thermosetting resin so as to form a close-packed structure. It is considered that the obtained spherical composite particles themselves have a close-packed structure due to the use of the spherical composite particles as the particles to be heat-treated. In the present invention, spherical composite particles having a high strength of 0.08 or less by Method II described later are obtained.

In the present invention, the saturation magnetization value is 40 to 1
Large spherical composite particles of 50 emu / g, especially 65 to 150 emu / g are obtained.

In the present invention, spherical composite particles having an appropriate conductivity of 10 ⁻⁶ to 10 ⁻⁴ S / cm in a direct current electric field of applied voltage of 15 V can be obtained.

[0074]

EXAMPLES Next, the present invention will be described with reference to Examples and Comparative Examples.

The average particle size in the following examples and comparative examples is shown by a value measured by a laser diffraction type particle size distribution meter (manufactured by Horiba Ltd.), and the particle morphology of the particles is determined by a scanning electron microscope. (JMS, JMS
-5300).

The carbon content was measured using a carbon / sulfur analyzer EMIA 2200 (manufactured by Horiba Ltd.).

The saturation magnetization is measured by a vibrating sample magnetometer VSM-3.
External magnetic field 10K using S-15 (manufactured by Toei Industry Co., Ltd.)
It is shown by the value measured under Oe.

The conductivity of the Wheatstone bridge 276
8 (manufactured by Yokogawa Electric Corp.).

The sphericity is S in which 200 or more particles are photographed.
From the EM photograph, the major axis diameter (l) and the minor axis diameter (w) of one particle were measured and expressed as a 1 / w ratio.

The strength was measured as follows. 50 g of the particles were placed in a 100 ml glass bottle, the lid was closed, and the mixture was shaken for 60 minutes in a paint conditioner. The particle size distribution of the sample particles before shaking treatment and after 60 minutes of shaking treatment is measured by a laser diffraction type particle size distribution meter,
Strength was determined by comparing the resulting particle size distributions. (Method I) A: No change or almost no change. B: There is some change. C: There is a change. The strength of the present invention is preferably "A".

The average particle diameters (a) (before shaking) and (b) (after shaking) of the particles before and after shaking were measured with a laser diffraction type particle size distribution analyzer, and the average before shaking treatment was measured. Ratio of difference between particle diameter (a) and average particle diameter (b) after shaking treatment and average particle diameter (a) before shaking treatment: (a-
The strength is indicated by b) / a. (Method II) The strength of the present invention is preferably (ab) / a <0.1.

Whether or not the phenol resin remains was confirmed by the following method. The spherical composite particles are used as a sample, and the sample is crushed. Then, 1 g of the crushed product is put into a test tube and heated by an open flame. After confirming that the decomposition product gas has condensed on the upper part of the test tube, it is cooled once, 3 ml of distilled water is added and boiled to dissolve the condensate in water, and then filtered. 1 ml of this liquid
It is possible to confirm that the phenol resin remains in the spherical composite particles by adding a small amount of the miron reagent to and giving a red color. The Miron reagent is prepared by dissolving 5 g of mercury in 5 g of fuming nitric acid and diluting it with 100 ml of distilled water.

Whether or not the epoxy resin remained was confirmed by the following method. Spherical composite particles are used as a sample, the sample is crushed, 1 g of the crushed product is dissolved in 100 ml of concentrated sulfuric acid in the cold, the mixture is stirred at room temperature, and 1 to 2 drops of 37% formalin is added to 1 ml of the solution obtained by filtration. Becomes orange. When this is poured into water and diluted, it immediately turns blue, and it can be confirmed that the epoxy resin remains in the spherical composite particles.

The residual amount of the thermosetting resin in the spherical composite particles can be determined by the following method.

The amount of thermosetting resin in the spherical composite particles is
From the measured value d of the specific gravity of the spherical composite particles, the measured value of the saturation magnetization of the spherical composite particles and the content of the ferromagnetic substance calculated from the measured value of the saturation magnetization of the ferromagnetic particles, the following is obtained. You can ask.

First, assuming that the specific gravity of the ferromagnetic particles is p, the specific gravity of the thermosetting resin is q, the specific gravity of carbon is r, and the contents in the spherical composite particles are x, y, and z% by weight, respectively. The specific gravity (d) of the spherical composite particles is represented by the following formula. d = (x + y + z) / [(x / p) + (y / q) + (z
/ R)] ... Then, since x + y + z = 100, z = 100−x
Together represented by -y, the saturation magnetization of the ferromagnetic particles as a sigma _1, whereas, when the saturation magnetization of the spherical composite particles and sigma _p, the content x of the ferromagnetic body, sigma _p / sigma _Since it is represented by ₁ × 100 , d = 100 / [(x / p) + (y / q) + (100−x
-Y) / r] ... In the above formula, the measured value d of the specific gravity of the spherical composite particles,
Inserting the specific gravity p of the ferromagnetic particles, the specific gravity q of the thermosetting resin, the specific gravity r of carbon, and the content x of the ferromagnetic material,
The content y (% by weight) of the thermosetting resin can be determined.

<Production of Spherical Composite Particles of Magnetic Particle Powder and Cured Phenolic Resin> Examples 1 to 3;

Example 1 400 g of spherical magnetite particles having an average particle diameter of 0.24 μm were charged in a Henschel mixer and stirred well, and then 2.0 g of a silane coupling agent (KBM-403; manufactured by Shin-Etsu Chemical Co., Ltd.) was added. And raise the temperature to about 100 ° C. 3
The spherical magnetite particles coated with the coupling agent were obtained by thoroughly mixing and stirring for 0 minutes.

Separately, in a 1-liter four-necked flask, 40 g of phenol, 60 g of 37% formalin, 400 g of magnetite subjected to lipophilic treatment, 12 g of 28% ammonia water, and 40 g of water were heated to 85 ° C. for 40 minutes while stirring. Then, the mixture was reacted and cured at the same temperature for 180 minutes to form a composite of magnetite particles and cured phenol resin.

Next, the content in the flask was cooled to 30 ° C., 0.5 l of water was added, the supernatant liquid was removed, and the lower layer precipitate was washed with water and air-dried. Next, this was dried under reduced pressure (50 mmHg or less) at 50 to 60 ° C. to obtain composite particles (hereinafter referred to as composite particles a).

The composite particles a thus obtained had an average particle diameter of 35 μm, and the scanning electron micrograph (×
2000), it had a spherical shape close to a true sphere.
Table 1 shows the main production conditions and various characteristics of the spherical composite particles.

Example 2 Composite particles (hereinafter referred to as composite particles b) were prepared in the same manner as in Example 1 except that the lipophilic treatment was not performed and the amount of phenol and the amount of water were changed. Got Table 1 shows the main production conditions and various characteristics of the obtained composite particles.

Example 3 Composite particles (hereinafter referred to as composite particles c) were obtained in the same manner as in Example 1 except that the kind and amount of the lipophilic treatment agent and the amount of water were changed. Table 1 shows the main production conditions and various characteristics of the obtained composite particles.

[0094]

[Table 1]

<Production of Spherical Composite Particles of Magnetic Particle Powder and Cured Epoxy Resin> Examples 4 to 6;

Example 4 In a 500 ml four-necked flask, 50 ml of water, 5.50 g of sodium hydroxide, 20 g of bisphenol A, 10 g of epichlorohydrin, 2.0 g of phthalic anhydride and a silane coupling agent having a particle surface of 0.5% by weight. KBM602
200 g of magnetite particles (particle size: 0.24 μm) coated with (manufactured by Shin-Etsu Chemical Co., Ltd.) were added and stirred.

After the temperature was raised to 80 ° C. at a rate of 1.0 to 1.5 / min, the mixture was continuously stirred at 80 ° C. for 1.5 hours to form a composite of magnetic particles and an epoxy resin. .

The product obtained was filtered off, washed with water and dried to obtain composite particles. The obtained composite particles had an average particle diameter of 37.0 μm and had a spherical shape close to a true sphere as shown in the scanning electron micrograph (× 2000) of FIG.

Main manufacturing conditions and various characteristics of the obtained composite particles are shown in Tables 2 and 3.

Examples 5 and 6 Examples 5 and 6 except that the type of magnetic particles, the type and amount of bisphenol, the type and amount of epichlorohydrin, the amount of sodium hydroxide, the type and amount of curing agent, and the amount of water were variously changed. Composite particles were produced in the same manner as in 4.

Main production conditions and various characteristics of the obtained composite particles are shown in Tables 2 and 3. In addition, Example 5 and Example 6
The toner charge amount in (1) could not be measured because the average particle size was small.

[0102]

[Table 2]

[0103]

[Table 3]

<Heat Treatment of Composite Particles> Examples 7 to 11, Comparative Example 1;

Example 7 1 kg of the spherical composite particle a obtained in Example 1 was used as the internal content of 10 kg.
1 l / min with nitrogen gas in a rotary heat treatment furnace
The temperature inside the heat treatment furnace was raised to 370 ° C., and the treatment was performed for 2 hours. After cooling to room temperature, it was taken out to obtain heat-treated spherical composite particles g.

As a result of analysis, phenol was detected in the obtained heat-treated spherical composite particles g, and since it exhibited conductivity, it was confirmed that the phenol was partially carbonized.

Heat-treated spherical composite particles g obtained here
A scanning electron micrograph (× 2000) of the above is shown in FIG. 3, and main manufacturing conditions and various characteristics are shown in Table 4.

In a 100 cc glass bottle, 50 g of heat-treated spherical composite particles were placed, and a paint conditioner (RE
When the saturation magnetization value and the conductivity were measured after shaking for 3 hours using D DEVIL), the initial values were almost maintained. From this, it was confirmed that the heat-treated spherical composite particles were hardly broken and had extremely high strength.

Examples 8 to 9 Heat treatment was carried out in the same manner as in Example 7 except that the type of composite and the heat treatment conditions were changed, and heat treated spherical composite particles h.
And i were produced. Table 4 shows the main manufacturing conditions and various characteristics at this time.

[0110]

[Table 4]

As a result of the analysis, each of the particles of the heat-treated spherical composite particles h and i obtained in Examples 8 to 9 was found to have phenol and exhibited conductivity. It was confirmed that it was partially carbonized.

After the heat-treated spherical composite particles obtained in Examples 8 to 9 were shaken in the same manner as in Example 7, the saturation magnetization value and the conductivity were measured, and the initial values were almost maintained. Was there. From this, it was confirmed that the heat-treated spherical composite particles were hardly broken and had extremely high strength.

Comparative Example 1 The magnetic particle powder used in Example 1 and a commercially available polyethylene resin (Admer NS101; manufactured by Mitsui Petrochemical Co., Ltd.) were kneaded in an extruder, pulverized and classified to obtain composite particles. Manufactured. The obtained composite particles were amorphous particles, had an average particle diameter of 33 μm, and had a magnetic particle powder content of 80 wt%. The composite particles are
The particles 1 obtained by heating at 1 ° C. for 1 hour showed no conductivity. Then, the particles 1 were easily broken when touched with a hand.

Example 10 1 kg of the composite particles obtained in Example 4 was placed in a rotary heat treatment furnace having an internal volume of 10 l, and the temperature in the heat treatment furnace was raised to 400 ° C. while flowing nitrogen gas at a flow rate of 1 l / min. It heat-processed for 1 hour. After cooling the inside of the heat treatment furnace to room temperature, the product was taken out to obtain heat treated spherical composite particles j.

The obtained heat-treated spherical composite particles j had an average particle diameter of 36 μm and had a spherical shape close to a true sphere (sphericity: 1.
1) was exhibited. Obtained heat-treated spherical composite particles j
Table 4 shows the manufacturing conditions and various characteristics.

The obtained heat-treated spherical composite particle powder j
It was confirmed that the epoxy resin was partially carbonized because the epoxy resin was detected and showed conductivity.

Example 11 Heat-treated spherical composite particles were produced in the same manner as in Example 10 except that the type of composite particles and the heat treatment conditions were variously changed.

Table 4 shows the production conditions and various properties of the heat-treated spherical composite particles.

A scanning electron micrograph (× 3500) of the obtained heat-treated spherical composite particles k is shown in FIG.

Epoxy was detected in the particles of the heat-treated spherical composite particles k obtained in Example 11 and showed conductivity, which confirmed that the epoxy resin was partially carbonized. .

[0121]

EFFECT OF THE INVENTION The spherical composite particle powder according to the present invention has a high strength, a large saturation magnetization value and an appropriate electric conductivity, so that it develops an electrostatic latent image such as a magnetic carrier or a magnetic toner. Material, electromagnetic wave absorber material, electromagnetic wave shield material, brake shoe and polishing material, lubrication material, magnetic separation material, magnet material, ion conversion resin material, immobilized enzyme carrier material, display It is suitable as a material for display materials, vibration damping materials, paint materials, rubber / plastic coloring materials, filling materials, reinforcing materials, and the like.

Further, since the spherical composite particle powder according to the present invention has high strength, it can maintain a large saturation magnetization value and an appropriate electric conductivity for a long period of time, and has a spherical shape. By virtue of this, there is an effect that the filling property is good and the dispersibility is excellent when kneading with the resin and mixing with the vehicle.

[Brief description of drawings]

FIG. 1 is a scanning electron micrograph (× 2000) showing the particle structure of the spherical composite particle powder obtained in Example 1.

2 is a scanning electron micrograph (× 2000) showing the particle structure of the spherical composite particle powder obtained in Example 4. FIG.

FIG. 3 is a scanning electron micrograph (× 2000) showing the particle structure of the spherical composite particle powder obtained in Example 7.

4 is a scanning electron micrograph (× 3500) showing the particle structure of the spherical composite particle powder obtained in Example 11. FIG.

Claims (4)

(57) [Claims] 1. A spherical composite particle comprising magnetic particle powder, a thermosetting resin, and carbon produced by carbonizing a part of the thermosetting resin, and having an average particle diameter of 1
Spherical composite particle powder consisting of spherical composite particles characterized by having a particle size of ˜1000 μm. 2. A magnetic particle powder content of 80 to 98% by weight, a thermosetting resin content of 13% by weight or less, and a carbon content of 2 to 15 produced by carbonizing the thermosetting resin. The spherical composite particle powder according to claim 1, which is in a weight percentage. 3. The spherical composite particle powder according to claim 1, wherein the thermosetting resin is a phenol resin or an epoxy resin. 4. Spherical composite particles having an average particle size of 1 to 1000 μm formed by binding magnetic particle powder with a thermosetting resin as a binder are heat-treated at a temperature of 350 ° C. or higher in an inert atmosphere to perform the thermosetting. The method for producing a spherical composite particle powder according to any one of claims 1 to 3, wherein a part of the functional resin is carbonized.