JPS6045261A - Production of magnetic toner - Google Patents

Abstract

PURPOSE:To enable simultaneous solution of fixability and resistance to offsetting by mixing three kinds of resins having respectively specific values of weight average mol.wt. and glass transition point and magnetic powder thereby preparing a magneic toner. CONSTITUTION:A resin A having <100,000 weight average mol.wt. and 50- 100 deg.C glass transition point, a resin B having 100,000-200,000 weight average mol.wt. and 35-60 deg.C glass transition point and a resin C having >200,000 weight average mol.wt. and 35-50 deg.C glass transition point as well as magnetic powder are compounded and mixed in such a way that the components A, B, C are incorporated at 60-70wt% the component A, 5-15wt% the component B and 20-30wt% the component C by the total weight thereof so as to make the entire part 100wt%. Copolymers of monomers selected from styrene, styrene deriv., acrylate and methacrylate are used for the resins of the components A, B, C.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing magnetic toner suitable for heat roll fixing in the field.

Toners for developing electrostatic images include toners for two-component developers containing a resin and a colorant, and magnetic toners having a composition in which magnetic powder is further added to the resin and the colorant. To apply these toners to, for example, the magnetic brush development method, the toner for the two-component developer is mixed with a carrier such as iron powder and used in the form of a brush using a magnetic field, and the magnetic toner is applied to a doctor blade or container wall. It is used in the form of a brush by being charged by friction with a magnetic field and used as a brush.

Compared to developing systems using toner for two-component developers, developing systems using magnetic toner do not require a mechanism to adjust the mixing ratio with the carrier, making the device more compact, and the toner adheres to the surface of the carrier. It has the advantage that it does not cause any inconvenience such as deterioration of image quality.

The heat roll fixing method is one of the fixing methods.

A method in which paper or a photoreceptor carrying a toner image is passed between heated thermal rolls, and the toner image is melted by heat and pressure between the rolls, thereby firmly adhering the toner image to the paper or photoreceptor. Ruru.

In the heat roll method, the heating temperature, the speed at which the pressure between the rolls is maintained at an appropriate level, the roll material, the toner material, etc. are related to the quality of the final toner image, that is, the quality of fixing, the presence or absence of offset, etc. A part of the toner image on the paper or photoreceptor is transferred to the roll side during fixing, and after one rotation of the roll, the toner transferred to the roll is transferred again to the paper or photoreceptor, staining the paper or photoreceptor. In the field of photography, this is called offset.

As a method for improving fixing properties by modifying toner materials, a toner using a styrene-methacrylic acid ester copolymer containing a long-chain alkyl group in the side chain as a toner resin (Japanese Patent Application Laid-Open No. 49-901.32 Toners containing plasticizers such as phthalate esters
12679) is known. The former is nonyl methacrylate.

Both methods are problematic because they require the use of expensive monomers such as decyl methacrylate, and the latter because the added plasticizer separates and migrates. Furthermore, it is difficult to say that these toners solve the problem of offset at the same time. One way to improve offset resistance by modifying toner materials is to use α, β-unsaturated ethylene polymers with a wide molecular weight distribution (!: i average molecular weight/number average molecular weight = 3.5 to 40). Toner used as resin for toner (Special Publications 1984
Japanese Patent Publication No. 52-3304) and the like are known. With these toners, offset resistance can be slightly improved, but fixing performance cannot be improved. In other words, there is no prior art that can solve fixing properties and anti-offset properties at the same time.

The present invention solves all of the drawbacks of the prior art.

That is, the present invention.

The weight average molecular weight is less than 100,000 and the glass transition point is 5.
Resin fBl at 0 to 100°C Resin with a weight average molecular weight of 100,000 to 20,000 and a glass transition point of 35 to 60'C and Fe2 Resin with a weight average molecular weight of over 200,000 and a glass transition point of 35 to 50'C and (Jun magnetic powder) component A, component (B) and component (C) are (Al component is 60 to 70) j amount % based on the total amount of these.
, (Bl component is 5 to 15% by weight and (C) component is 2% by weight)
0-30% by weight makes the whole 100! The present invention relates to a method for producing a magnetic toner characterized by blending and mixing so that the i.sub.i is 1%.

The resin used in the present invention is obtained by polymerizing or copolymerizing α,β-unsaturated ethylenically monomers.

As the polymerization method, all conventionally known polymerization methods such as emulsion polymerization, suspension polymerization, solution polymerization, and bulk polymerization can be used.

The polymerization temperature is preferably about 50 to 100°C.9 Polymerization catalysts commonly used include peroxides such as benzoyl peroxide, a/bis compounds such as azobisisobutyronitrile, sodium persulfate, potassium persulfate, etc. can be used.

The polymerization catalyst is preferably used in an amount of 0.1 to 5 times the amount of monomer.

Examples of α,β-unsaturated ethylenic monomers include:

Styrene, α-methylstyrene, p-methylstyrene,
Styrene or its derivatives such as pt-butylstyrene, p-chlorostyrene, divinylbenzene, methacrylic acid, methyl methacrylate, ethyl methacrylate, globyl methacrylate, butyl methacrylate, pentyl methacrylate, hexyl methacrylate, Hegtylated methacrylate, octyl methacrylate, nonyl methacrylate, decyl methacrylate, undecyl methacrylate, dodecyl methacrylate, β-hydroxyethyl methacrylate.

Methacrylic acid or its esters such as glycidyl methacrylate, acrylic acid, methyl acrylate.

Ethyl acrylate, propyl acrylate, butyl acrylate, pentyl acrylate, hexyl acrylate, hebutyl acrylate, octyl acrylate, nonyl acrylate, decyl acrylate, undecyl acrylate, dodecyl acrylate, β-hydroxy acrylate Acrylic acid or its esters such as ethyl, glycidyl acrylate,
Examples include vinyl acetate, vinyl chloride, acrylonitrile, methacrylonitrile, and butyl vinyl ether. Preferred examples include styrene, styrene derivatives, methacrylic esters, acrylic esters, etc. Especially preferred as methacrylic esters and acrylic esters are alkyl esters having an alkyl group having 1 to 5 carbon atoms.

The weight average molecular weight of the resin can be adjusted by appropriately selecting the polymerization method exemplified above, by increasing or decreasing the amount of polymerization initiator, or by using a chain transfer agent. The weight average molecular weight can be measured by gel permeation chromatography, light scattering, or the like. What is the glass transition temperature of the resin?

It can be adjusted by polymerizing or copolymerizing a suitable one from among the α,β-unsaturated ethylenically monomers exemplified above.

For example, on pages 16-32 of "Mechanical Properties of Polymers" by E. Nelsen, translated by Shigeharu Onoki (Kagaku Doujin), α
, the glass transition temperature of β-unsaturated ethylene polymers, and the calculation method of the glass transition temperature of copolymers are shown on page 26. system monomers can be selected. The glass transition temperature of a polymer or copolymer is determined by the differential
Thermo Ana 7; 5 lysis method, thermo mechanical
It can be measured by analysis method.

In the present invention, one or more resins having a weight average molecular weight of less than 100,000 (component (A)) 60 to 70% by weight.

One or more resins with a weight average molecular weight of 100,000 to 200,000 ((B
(component) 5 to 15% by weight and one or more resins having a weight average molecular weight exceeding 200,000 (component (C)) 20 to 30% by weight. If the composition ratio of the constituent components is less than this range, the fixing properties will be poor.

On the other hand, if the amount is too large, the offset resistance will be poor. On the other hand, if the amount of component (B) or component (C) is small, the offset resistance will be poor.

If it is too large, the fixing properties will be poor.

The resin used in the present invention has a glass transition temperature (T1) of the component (5) of 50 to 100°C, a glass transition temperature (T2) of the component (B) of 35 to 60°C, and a glass transition temperature of the component (C). (T3) is configured to be 35 to 50°C.

If the TI is less than 50°C, the offset resistance and thermal stability of the toner will be poor. On the other hand, when T1 exceeds 100° C., fixing performance is poor. If T2 or T3 is less than 35° C., not only the offset resistance is poor but also the storage stability and thermal stability of the toner are poor. on the other hand.

If T2 exceeds 60°C or T3 exceeds 50°C, the fixing properties are poor.

In the present invention, magnetic powder and, if necessary, colorants, charge control agents, and other additives are added at the time of manufacture.

Examples of magnetic powder include fine metal powders such as iron, manganese, nickel, and cobalt, as well as iron and manganese.

The thickness is preferably 1 μm or less.

The magnetic powder and the magnetic powder, the component (B), and the component (C) are calculated by the amount of magnetic powder divided by the total amount of the component (A), component (B), and component (C).

It is preferably used in a range of 5/95 to 70/30 (weight ratio), particularly preferably 20/80 to 60/40 (weight ratio).

When the above ratio is less than 5/95, the magnetism decreases.

If it exceeds 7 o,'a O, it becomes difficult to produce a magnetic toner and the fixability tends to decrease.

Carbon black and iron oxide pigments are used as coloring agents.

Phthalocyanine blue, phthalocyanine green.

Known pigments such as azo, anthraquinoy, and triallyl meta/dyes can be used.

As the charging a1η moderating agent, nigrosine dyes, fatty acid-modified nigrosine dyes, metal-containing nigrosine dyes, metal-containing fatty acid-modified nigrosine dyes, chromium complexes of 3,5-di-tert-butylsalicylic acid, and the like can be used.

Other additives that can be used include silica powder, hydrophobic silica powder, polyolefin, paraffin wax, fluorocarbon compounds, fatty acid esters, partially saponified fatty acid esters, fatty acid amides, fatty acid metals, and the like.

These materials are mixed, for example, by the following method to produce a magnetic toner.

The weighed materials are premixed using a W cone, a blender, a Henschel mixer, etc., and then kneaded using a pressure kneader, a Banbury mixer 9 hot roll, an extruder, etc. at a temperature at which the resin melts. After cooling, it is coarsely ground using a feather mill, bottle mill, valveizer, hammer mill, etc., and then finely ground using jet air. Next, use an AccuCut, Alpine classifier, etc. to divide the size, preferably 5 to 3
The particle size is adjusted to 0 μm.

Next, examples of the present invention will be shown. Hereinafter, "part" means "part by weight"
means.

Example 1 (1) Production water 4 of copolymers (a-1) and (a-2)
7 parts, 1.25 parts of tricalcium phosphate, 0.03 parts of sodium dodecylbenzenesulfonate, and 0.015 parts of sodium chloride to which were added 40 parts of styrene, 10 parts of butyl acrylate, and benzoyl peroxide. A homogeneous solution consisting of 1.4 parts was added and, under stirring, 90
Suspension polymerization was carried out at ℃ for 6 hours. After the polymerization is completed, the copolymer (
a-1) was isolated and dried. Copolymer (a-1) had a weight average molecular weight of 48,000 and a glass transition temperature of 58°C.

In addition, in the above, a copolymer (a-2
) was obtained. Copolymer (a-2) has a weight average molecular weight of 3.7
However, the glass transition temperature was 57°C.

(2) Production of copolymer (b-IJ) In the production of the copolymer (a-1) of (11) above.

The amounts of styrene, butyl acrylate and benzoyl peroxide used were 37.5 parts each.

Same procedure except that 12.5 parts and 0.4 parts were used.

A copolymer (b-1) was obtained. Copolymer (b-1) is 1M
The t-average molecular weight was 110,000, and the glass transition temperature was 46°C.

(3) Production of copolymer (C-1) Add polyvinyl alcohol to 51.2 parts of water! 1 aqueous solution 8 parts, sodium laurate 0.4 part and sodium persulfate 0
, 28 parts of styrene, 12 parts of butyl acrylate and 0.004 parts of divinylbenzene in an aqueous medium in which 4 parts of divinylbenzene were dissolved.
Add a homogeneous solution consisting of 50%.

The reaction was carried out at 90° C. for 6 hours while stirring. During the reaction, the emulsification shifted to suspension. After the reaction was completed, the obtained copolymer (C-1) was isolated and dried. The copolymer (C-1) had a weight average molecular weight of 1.3 million and a glass transition temperature of 37°C.

In addition, in the above, the weight average molecule 1 was measured by creating a calibration curve using monodisperse standard polystyrene using a gel perminium-7 chromatograph, and the glass transition temperature was measured according to the thermomechanical analysis method (hereinafter did the same). Copolymer (C-1) Contains 15% by weight of a component insoluble in tetrahydrofuran, a solvent measured by Hakken Vermeation Chromatography. Therefore, copolymer (C-1)!
! The weight average molecular weight of 300,000 is the value of only the soluble components (the same applies below).

(4) Production of magnetic toner Copolymer (a-1) 9% by weight, copolymer (a・2) 18% by weight
．． 9% by weight, and 4.5% by weight of copolymer (b-1).

Copolymer (C-1) 12.6% by weight, iron ferrite (MG-WS manufactured by Mitsui Mining & Co., Ltd., particle size 0.1-0.3 μm)
) 45% by weight, carbon black (carbon black $44 manufactured by Mitsubishi Chemical Corporation) 7% by weight, fatty acid-modified nigrosine dye (oil black BY manufactured by Orient Chemical Industries, Ltd.)
After melting and mixing triple IU, crush and classify into 5-30μIn
A magnetic toner A having a particle size of .

(5) Evaluation Using Canon NP2O0-J (a copying machine manufactured by Canon Co., Ltd.), charging, exposure, development, and transfer to paper were performed to create an unfixed toner image. Next, the unfixed toner image was fixed at a linear speed of 70 mm/sec and a pressure between the rolls of 0.5 using a fixing device consisting of a Teflon-coated heat roll on the upper side and a silicone rubber-coated roll on the lower side, in which the temperature of the upper roll can be changed.
The offset resistance and fixing properties were evaluated by passing the film at Kgf/cm. The results are summarized in Table 1.

Comparative Example 1 A copolymer (a-3) was produced by suspension polymerizing 35 parts of styrene and 15 parts of butyl acrylate in the same manner as the copolymer (a-1) of Example 1. , copolymer (
Copolymer (a-3) instead of a-1) and (a-2)
) was used to prepare magnetic toner B. Copolymer (a-
The molecular weight of 3) was 40,000, and the glass transition temperature was 35°C. The offset resistance and fixing properties were evaluated in the same manner as in Example 1.

The results are summarized in Table 1.

Comparative Example 2 32 parts of styrene, 8 parts of butyl acrylate and 0.004 parts of divinylbenzene were added to the copolymer (c-1) of Example 1.
The copolymer (
c-2) was obtained. In Example 1, copolymer (c-1
Magnetic toner C was prepared by using copolymer (c-2) in place of ).

The copolymer (c-2) had a molecular weight of 320,000 and a glass transition temperature of 60°C. The copolymer (c-2) contained 16% by weight of tetrahydrofuran-insoluble matter. The offset resistance and fixing properties were evaluated in the same manner as in Example 1, and the results are summarized in Table 1.

Comparative Example 3 35 parts of styrene and 15 parts of butyl methacrylate were added to Example 1.
A copolymer (b-2) was obtained by suspension polymerization in the same manner as in the production of the copolymer (b-1).

Magnetic toner D was produced in exactly the same manner as in Example 1 except that copolymer (b-2) was used instead of copolymer (b-1).
was prepared. The copolymer (b-2) had a molecular weight of 150,000 and a glass transition temperature of 70°C. The offset resistance and fixing properties were evaluated in the same manner as in Example 1, and the results are summarized in Table 1.

Comparative Example 4 In Example 1, the copolymer (a-1) was 18% by weight, the copolymer (a-2) was 18% by weight, and the copolymer (b-1) was 4% by weight.
．． Magnetic toner B was prepared in exactly the same manner except that 5% by weight and 4.5% by weight of copolymer (c-1) were used. The offset resistance and fixing properties were evaluated in the same manner as in Example 1, and the results are summarized in Table 1.

Comparative Example 5 In Example 1, 9% by weight of copolymer (a-1), 13.5% by weight of copolymer (a-2), and 13.5% by weight of copolymer (b-1)
Magnetic toner F was prepared in exactly the same manner except that 4.5% by weight of the copolymer (c-1) and 18% by weight of the copolymer (c-1) were used. Anti-offset properties and fixing properties were evaluated in the same manner as in Example 1,
The results are summarized in Table 1.

Comparative Example 6 In Example 1, 2.3% by weight of copolymer (a-1),
18.9% by weight of copolymer (a-2), 18.9% by weight of copolymer (b-
1) and 12% by weight of copolymer (c-1).
．． Magnetic toner G was prepared in exactly the same manner except that 6% by weight was used. The offset resistance and fixing properties were evaluated in the same manner as in Example 1, and the results are summarized in Table 1.

Comparative Example 7 In Example 1, the copolymer (b-1) was not used, but the copolymer (a-1) was 9% by weight, and the copolymer (a-2) was 23.4% by weight.
The offset resistance and fixing properties were evaluated in exactly the same manner except that 12.6% by weight and copolymer (c-1) were used, and the results are summarized in Table 1.

Example 2 A copolymer (a-4) was produced by suspension polymerizing 35 parts of styrene and 15 parts of butyl methacrylate in the same manner as in the production of (a-1) of Example 1.

Copolymer (a-4) had a weight average molecular weight of 40,000 and a glass transition temperature of 70°C.

20 parts of styrene and 30 parts of butyl methacrylate were subjected to suspension polymerization in the same manner as in Example 1 (b-1) to obtain a copolymer (b-3). The copolymer (b-3) had a weight average molecular weight of 120,000 and a glass transition temperature of 49°C.

The copolymer of Example 1 (C-
Emulsion-suspension polymerization was carried out in the same manner as in the production of 1) to obtain a copolymer (C-3). The copolymer (C-3) has a weight average molecular weight of 400,000 [However.

The copolymer (ca) contained 17% by weight of a component insoluble in tetrahydrofuran, a measurement solvent for gel permeation chromatography, and was heated at a glass transition temperature of 42°C.

Next, in Example 1, copolymer (a-1).

In place of (a-2), (b-1) and (C-1) (7), 29.2% by weight of copolymer (a-4) and copolymer (
b-3) at 4.5% by weight and copolymer (C-3) at 1% by weight.
Magnetic toner I was prepared in exactly the same manner except that 1.3% by weight was used. The offset resistance and fixing properties were evaluated in the same manner as in Example 1, and the results are summarized in Table 1.

Margin 1-) The magnetic powder toner obtained by the present invention has a fixing temperature of 15
Both offset resistance and fixing properties are excellent in the temperature range of 0 to 190°C.

Claims (1)

[Claims] 1. (A) Resin CB1 with a weight average molecular weight of less than 10,000 yen and a glass transition point of 50 to 100°C. A resin CB1 with a weight average molecular weight of 100,000 to 20,000 yen and a glass transition point of 35 to 60° C. Component (A), component (B) and component (C) are the total amount of the resin and fc) resin with a weight average molecular weight exceeding 200,000 and the glass transition point of 35 to 50'C, and ■) magnetic powder. , the prisoner component is 60 to 70% by weight, (B
) component is 5 to 15% by weight [C) component 7 > f20 ~
30fi, it% is 100. 1. A method for producing a magnetic toner, which comprises blending and mixing the toner so that the amount is equal to or more than 1. 2. The resins of the (Al component, (B) component and (C1 component) are made of a polymer of at least one monomer selected from the group consisting of styrene, styrene derivatives, acrylic esters and methacrylic esters. A method for producing a magnetic toner according to claim 1. 3. Amount of magnetic powder and component (A). (Bl component and (
C) The total amount of ingredients is 5/95 to 70/30 for the former/latter
(weight ratio).