JPS6021054A - Pressure fixable magnetic toner - Google Patents

Abstract

PURPOSE:To enhance fixability at low pressure and to improve storage stability at high temp. and resistance to blocking due to vibration by using a specified resin compsn. as a resin component. CONSTITUTION:A resin compsn. used as a resin component is composed of oxidized polyolefin wax (POW) having an oxygen content of >=0.05wt% and higher fatty acid amide, and it has >=80 deg.C softening point and <=500kg/cm<2> compression yielding value. POW of such oxidized POW used for this compsn. may be homopolymers of ethylene and propylene and copolymers of >=2 kinds of olefin monomers, and addition of oxygen to >=0.005wt% enhances transfer efficiency. The used higher fatty acid amide is in the range of 6-50C, and the used fatty acid is of >=12C, such as lauric acid, and it is, preferably, palmitic acid, etc. The use of such a resin compsn. forms a pressure fixable magnetic toner good in fixability at low pressure and storage stability at high temps. and resistance to blocking due to vibration.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic toner for pressure fixing used in electrophotography, magnetic printing, etc.

"jQ, as a copying method using child photos, for example, Se
.

An electrostatic latent image is formed on a photoreceptor such as ZnO or an organic photoconductor, and developed by a magnetic brush method using a magnetic developer.
2. Description of the Related Art A method is generally known in which a final image is obtained by transferring an image onto a transfer sheet such as plain paper and then fixing the image. The magnetic developer used in this copying method has traditionally been a two-component developer, which is a mixed powder of a magnetic carrier and a non-magnetic toner in which coloring pigments, dyes, etc. are added to a fixing resin. .

However, when using this two-component developer, it is necessary to provide a means for keeping the toner concentration in the developer constant and a means for uniformly mixing toner and carrier in the developing device, which makes the developing device large. There is a problem of complication. In addition, since the carrier particles are mixed and stirred with the toner for a long time, a toner film is formed on the surface of the carrier particles, and the triboelectric properties of the carrier deteriorate by 1 degree, so it is necessary to replace the carrier regularly. was there.

Therefore, it has been proposed to develop electrostatic latent images using a one-component magnetic toner mainly composed of resin and magnetic powder without using carrier particles as a magnetic developer. It has been put into practical use in a system in which special recording paper such as recording paper is used to directly fix after development, and then it has also been put into practical use in an electrophotographic copying system that includes the above-mentioned transfer process. Furthermore, magnetic toner is used not only in copying systems using electrophotography and electrostatic recording, but also in magnetic recording systems using magnetic drums.

In each of the above copying methods, there are known toner image fixing methods such as a heating fixing method using an oven or heated roll, and a pressure fixing method using only pressure at room temperature, but there is no need for preheating time, that is, a quick start method. The pressure fixing method is becoming popular because it has advantages such as being able to perform the following steps and consume less power.

As a toner used in this pressure fixing method, for example, a toner which is modified by blending a thermoplastic resin with an aliphatic component such as wax as a main component is known (% Publication No. 44-9880). For example, Japanese Patent Publication No. 49-17739
A capsule type pressure fixing toner having a core of a viscous resin as described in the above publication is also known. Further, JP-A-50-50042 describes a magnetic toner using wax and an ethylene-vinyl acetate copolymer as resin components. Furthermore, JP-A-51-36947 describes a magnetic toner using a heat-reactive resin or epoxy resin and an ethylene-vinyl acetate copolymer as resin components. In addition, special public service No. 54-3373
3 to 300 kg/c as stated in the publication.
A magnetic toner using a resin obtained by modifying a waxy compound having a yield value of rn 2 with an ethylene-vinyl acetate copolymer having a clear yield value has also been put into practical use.

Magnetic toner for pressure fixing is required to have good fixing properties, good storage stability at high temperatures, and excellent offset resistance, but conventional toners meet all of these requirements. It was difficult to meet. For example, the toner described in Japanese Patent Publication No. 44-9880 requires pressure for fixing, and has the problem of being prone to agglomeration during storage.

In addition, the adjustment method for microcapsule type toner is glued.

It is difficult and impractical to obtain toner with stable characteristics. Furthermore, toners using 4!1 fat, which is a wax modified with ethylene-vinyl acetate copolymer, have superior fixing properties, storage stability, and fluidity compared to conventional ones, and have been put into practical use. Since wax has poor compatibility with other resins, there are some difficulties in storage stability and adhesion to photoreceptors.

An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, and to provide a magnetic toner for pressure fixing that exhibits good fixing properties especially at low pressure, has good storage stability at high temperatures, and has good anti-blocking properties due to vibration. O The magnetic toner for pressure fixing of the present invention has an oxygen content of 0.05
Made of oxidized polyolefin wax and higher fatty acid amide of polyamine with a softening point of 80°C
Is it above and the compressive yield value is 500kl? /Cm2 or less and magnetic powder as its main components 〇Generally, resins can be roughly classified based on their mechanical properties into those that undergo elastic deformation, those that cause brittle fracture, and those that undergo plastic deformation. Among them, toners that undergo plastic deformation under a predetermined pressure (approximately 3 to 300 k19/crn) are used for pressure fixing toners, specifically polyethylene wax, polyolefin wax, and amide wax. Waxes such as wax are used.However, among the above waxes, those with a high softening point (approximately 90°C or higher) have good storage stability, but have a high compression yield value, so they have poor fixability. Waxes with a low softening point have a low compression yield value and exhibit good fixing properties, but they have problems with storage stability at high temperatures. Therefore, waxes are usually used in combination with other resins, but as described above, waxes have poor compatibility with other resins, which causes various problems.

As a result of various studies conducted by the present inventors, we have developed a resin composition consisting of an oxidized polyolefin wax and a higher fatty acid amide, which have a softening point of 80°C or higher and a compressive yield value of 500 kg/c or lower, among those belonging to the polyolefin category. It has been found that a magnetic toner for pressure fixing which can achieve the above object can be obtained by using the present invention as a toner resin.

In the present invention, it is essential that the softening point of the resin composition consisting of oxidized polyolefin wax and higher fatty acid amide used as a resin component is in the range of 80°C or higher, and more preferably in the range of 100 to 160°C. It is preferable that there be. If the softening point of the polymer is lower than 80°C, the storage stability at high temperatures will be poor. Is the compressive yield value of the resin composition 500 kl? /cm,” and must be within the range of 30 to 500.
7 cm, particularly preferably in the range of 40 to 400 kg 7 cm. Compressive yield value is 500k177c
If it is larger than m2, the fixing properties of the magnetic toner will be poor.

The content of the oxidized polyolefin wax constituting the resin composition must be in the range of 0.05 Ji or more, and more preferably in the range of 0.05 to 10% by weight. Further, the intrinsic viscosity [η] (value measured at 135°C in a decalin solvent) of the oxidized polyolefin wax is usually 0.06 to 0, s d4/y
, preferably 0.08 to 0.4 dt/r (7
) range, and its confidentiality is usually between 0.91 and 0.98
f/, □3, its softening point is usually in the range of 80 to 130°C, preferably 90 to 130°C, and its compressive yield value is usually in the range of 30 to 500 kg/cm.
If the oxygen content of the oxidized polyolefin is less than 0.05 m/crr, preferably in the range of 40 to 400 m/crr, the transfer efficiency will be significantly reduced.

The polyolefin waxes constituting the oxidized polyolefin wax include ethylene, propylene, 1-butene,
3-methyl-1-pude/, ■-pente/, 4-methyl-
It is a homopolymer of 1-bencane, 1-octene, 1-decene, 1-dodecene, etc., or a copolymer of two or more of these components.

Further, the higher fatty acid amide constituting the resin composition usually has a carbon atom number in the range of 6 to 50, a molecular weight in the 8.1Σ range of 120 to 1500, and a softening point usually in the range of 40 to 150°C. Preferably, it is within this range. Specifically, the higher fatty acids constituting the higher fatty acid amide include fatty acids having carbon atoms of 12 or more, preferably 16 or more, such as lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, and linuric acid. I can give an example.

In addition, the amine component constituting the higher fatty acid amide includes primary amines such as ammonia, methylamine, ethylamine, butylamine, caprylamine, laurylamine, myristylamine, palmitelamine, and stearylamine, ethylenediamine, trimethylenediamine,
Examples include tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, diethylenetriamine, and triethylenetetramine.

The oxidized polyolefin and higher fatty acid amide constituting the resin composition may be a simple blend, or both may further react. The proportion of fatty amide in the oxidized polyolefin wax ranges from 50 to 95%, preferably 6%.
The higher fatty acid amide is usually 50 to 5% by weight, preferably 40 to 10% by weight.
It is within the range of M quantity.

The physical properties of the oxidized polyolefin wax used as a resin component in the present invention and the resin composition consisting of the oxidized polyolefin wax and higher fatty acid amide were measured by the following method.

(1) Softening point measured by constant load penetration method (TMA method). That is, a plate-like sheet with a thickness of 1 mrn was created from the polymer by compression molding, and this small piece sheet (3 mm x 3 mm) was molded into a du Pont.
CompanyN Thermal Mechan-ical An
Load it into aLijer and set the needle load to 49 f and chamber τ'.

The temperature was increased at a rate of 5° C./min, and the temperature was read when the button entered 0.1 mm.

(2) Compressive yield value 10mm
A 10 mm x 10 mm square sample was prepared, and this sample was deformed at a compression modification speed of 2 mm/min using a compression jig manufactured by Instron, and its compression yield value was read.

However, the intrinsic viscosity [η] of each oxidized polyolefin wax, which is a constituent component of the resin composition, is 13 in decalin solvent.
Measured at 5°C.

However, the molecular weight (number average molecular weight) of higher fatty acid amide is
It was measured by mass spectrometry using field desorption ionization method in toluene at 100°C.

The magnetic toner of the present invention contains magnetic powder as an essential component along with the above resin. Examples of magnetic powders that can be used include iron,
Metals such as nickel, chromium, cobalt and their alloys,
Examples include various substances exhibiting ferromagnetism, such as iron oxides such as ferrite, hematite, and magnetite. These magnetic powders preferably have an average particle size of 0.1 to 3 μm (more preferably 0.5 to 1 μm) in order to be included in the toner particles. Among the above-mentioned magnetic powders, magnetite (FesO4) is preferred in terms of magnetic properties and metal phase.

The magnetic properties of toner are determined by the type of magnetic powder and its content, but if the coercive force (zHc) is too low, the toner will tend to aggregate during use, while if it is too high, the content of acicular particles will increase. Therefore, the volume of magnetite increases, so it is usually 80 to 4000e (preferably 100 to aooOe).
) is used.

In addition, the saturation magnetization (O8) of the toner is determined by the content of magnetic powder, but if it is too low, the conveyance on the magnet roll will decrease, while if it is too high, the fixing performance will decrease, so it is 50 to 65 tmn/gr. Adjusted to range. Commercially available magnetite has engineering Ha of 1000e and 2000e.
and 4000e, so in order to obtain x Hc between these, magnetite of 24Φ class or higher may be mixed and used. The content of the magnetic powder may be selected within the range of 30 to 80% by weight based on the total weight of the toner. This is because if the content of the magnetic powder is too small, it will not easily scatter from the magnet roll, while if the content of the magnetic powder is too large, the fixing properties will be reduced.

Further, the magnetic toner of the present invention may contain one or more of a color tone pigment, a charge control agent, a resistance modifier, and a fluidity modifier blue. Examples of pigments that can be used include black pigments such as carbon black, lamp black, and aniline black, as well as various other pigments. Examples of charge control agents include nigrosine dyes having positive triboelectric properties, nigrosine dyes modified with higher fatty acids, and metal-containing M4 (Cr) azo dyes having negative triboelectric properties.

Conductive fine particles such as carbon black can still be used as the resistance modifier. St 0 as a fluidity regulator
Two particles are commonly used. This SiO2 is effective in imparting negative chargeability to the toner since it has a polar group. Depending on the manufacturing method, carbon black can also have the functionality of the seven gods, and in that case, it can also be used as a charge control agent. However, the amount of the various additives mentioned above is preferably less than 10% by weight based on the total amount of the toner.

The magnetic toner of the present invention can be manufactured by a known method using the various materials mentioned above. That is, the so-called pulverization method involves premixing the raw materials, heating, kneading, cooling, assimilating, and pulverizing the pulverized powder, spheroidizing the pulverized powder, adding carbon black if necessary, and then classifying the powder, or using magnetic powder in an organic solvent solution of resin. It can be produced by the so-called spray drying method, which involves dispersing it in water, spray drying it, and then classifying it.

The magnetic toner of the present invention has a so-called C
It can be used in the PC method or the PPC method including a transfer process, but when used in the CPC method, the volume resistivity of the toner is preferably 10 Q-crn or less (preferably lO~11). -cm), while PPC
When used in this method, the volume resistivity of the toner is preferably 10 8 Ω·cm or more from the viewpoint of transferability.

Plain paper (volume resistance 1 (112 Ω cm)
(below), it is common to use a magnetic toner with a volume resistivity of 1014 Ω·cm or more; however, according to the magnetic toner using the above-mentioned polymer of the present invention, the toner has a resistance of 10' to 1011 ΩΦcm. There is no smearing of the letters even in the case of IA, and the transfer rate is about 85% or more.1
,.

It is possible to transfer to plain paper at a high rate.

The volume resistance value of the toner is V with an inner diameter of 3.05 mrnφ.
The value is measured in a DC electric field of /cm.

The particle size of the toner may be in the range of 5 to 50 μm, especially when used in the PPC method,
It may be in the range of μm.

Examples of the present invention will be shown below.

[Example 1] Oxidized polyethylene wax with [η] of 0.13 di/f, softening point of 100°C, compressive yield value of 180 kg/bacteria, and oxygen content of 0.5% by weight, and molecular weight of 600, softening point is 103℃ of ethylene bisstearic acid amide at 8℃:2
Mix at a weight ratio of 0 and 180°C in a flask.
Melting and mixing was performed under hr conditions, the softening point was 138℃, and the compressive yield value was 130kl? /Cl71 resin composition was obtained.

40 parts by weight of the above resin composition and 60 parts by weight of magnetite (Toda Kogyo's EPT 500) were premixed in a dry manner, then heated in a kneader at a temperature of about 180°C, and then cooled and solidified. Next, the cooled solidified product is pulverized with a jet mill, the pulverized powder is introduced into a hot air stream at 100°C for heat treatment, carbon black (Mitsubishi Kasei 44) is added and mixed, and the particle size is 5. A magnetic toner of ~25 μm was prepared. Five types of magnetic toners shown in Table 1 were prepared by varying the heat treatment temperature of this composition and the amount of carbon black added.

Table 1 [Example 2] Volume resistivity was 109 under the same conditions as in Example 1, except that the amount of polymer and magnetite added was 50 parts by weight each, and the amount of carbon black added was 0.3 parts.・
A magnetic toner (Na6) was prepared.

[Example 3] [η] is 0.134 dt/l, softening point is 102°C, pressure! +iii polyethylene wax with a yield value of 2001<g/crl, [η] of 0.13 di/l, a softening point of 95°C, a compressive yield value of t5okg/c++t, and an oxygen content of 0.6% by weight Oxidized polyethylene wax with a molecular weight of 520 and N stearyl stearic acid amide with a softening point of 74°C were mixed at a weight ratio of 60:40:40, and melt-mixed in a flask at a temperature of 180°C and 1 hour. , softening point is 95℃, compressive stress is 140kg/
(Resin composition d was obtained.

40 parts by weight of the above resin composition and magnetite (EPT50)
0 and MAT-230 at a weight ratio of 50:50) (adjusted to 02000e) were axially mixed for 5 minutes in a super mixer, and then mixed in a kneader for about 17
After heating and cross-wiring at a temperature of 0°C, the mixture was cooled and solidified. Next, the cooled solidified product is pulverized with a jet mill, and the pulverized powder is introduced into a hot air stream at 140°C to perform a spheroidization heat treatment, and carbon black (
0.8 parts by weight of Na44) manufactured by Mitsubishi Kasei was added and mixed, and the mixture was classified to prepare a magnetic toner having a particle size of 5 to 25 μm.

The volume resistance of this magnetic toner (Nα7) is 1011Ω・
cm, and the yield energy is 7.4 kg・Cm/CI
It was f.

[Example 4] Volume resistivity was 10 under the same conditions as in Example 3 except that the resin composition and magnetite were each mixed in an amount of 50 parts by weight.
A magnetic toner (Na8) with a diameter of 119 cm was prepared.

[Comparative Example 1] Wax (manufactured by Mitsui Petrochemical Industries, Ltd.) was used as the resin component.
HI WAX 400P) and ethylene/vinyl acetate copolymer (Allied Chemical mP CP 400) at 7=3
A magnetic toner was prepared under the same conditions as in Example 1 (however, no carbon black was added) except that the composition was mixed at a weight ratio of .

[Comparative Example 2] Wax (manufactured by Mitsui Petrochemical Industries, Ltd.,
A magnetic toner was prepared under the same conditions as in Example 3 except that HIWAX II OP) was used.

Using the magnetic toners of the above Tanifu Example and Comparative Example,
℃, 60% R, H- environment using a commercially available electrophotographic copying machine (SC120 made by Copia), using plain paper (volume resistance 10"Q @ cm) as transfer paper, 40X 40
Imaging and fixing of solid black image of mm (linear pressure 181v/
i) was performed. Fixability was determined by (A) performing a peeling test using cellophane tape (product name) on the image area, and determining the ratio of the copy density after peeling off to the copy density before peeling off (100%).
and (B) a gauze test was performed, and the ratio (100 percent) of the copy density after rubbing and the copy density before rubbing was calculated and evaluated. The storage stability was evaluated by leaving the magnetic toner on a petri dish at a temperature of 55° C. for 100 hours.

In addition, the anti-blocking property due to vibration is confirmed by holding a non-magnetic cylindrical container (outer diameter 60 mmφ, inner diameter 58 mmφ, length 100 mm) vertically with one end sealed, filling the inside with 1002 magnetic toner, and then capping the other end. Then, the cylindrical container was vibrated up and down for 2 minutes at a frequency of 20 times/min and an amplitude of 2 mm, and the toner agglomeration state before and after vibration was observed and evaluated. As shown in Table 2.

As is clear from Table 2, the magnetic toner of the present invention (Nα1
-8) are preferred for their fixing properties, storage stability at high temperatures, and vibration-blocking properties compared to conventional magnetic toners. However, although the magnetic toner of Comparative Example 2 is better than the others in terms of rotational properties, it has the drawbacks of poor storage stability and easy filming phenomenon, so it is difficult to use in practical applications.
j, (No.

Further, the magnetic toner of the present invention has a particle size of 1()7 to 10"Q a
It is also superior to conventional magnetic toners in that high transfer efficiency is obtained even with a volume resistivity in the range 1i1J of C.

Agent: Patent Attorney Takashi Honma

Claims (1)

[Claims] 1. In a magnetic toner for pressure fixing whose main components are at least resin and magnetic powder, the oxygen content as the resin component is 0.0.
Pressure characterized by using a &J fat composition consisting of an oxidized polyolefin wax of 5-fold Jjf% or more and a higher fatty acid amide, and having a softening point of 80°C or more and a compression yield value of 500 kg/cm" or less Magnetic toner for fixing.