JPS60117252A - Electrostatic charge image developing toner - Google Patents

Abstract

PURPOSE:To save labor, to speed up operation, and to form a high-quality image by enclosing a magnetic material and carbon black, forming particles having a Wadell's practical sphericity in a substantially spherical range, and controlling the content of volatile matters in the carbon black to a specified value or less. CONSTITUTION:The toner to be used is substantially spherical and uniform in particle diameter, and has a Wadell's practical sphericity of 0.95-1.00, and a number average particle diameter of 5-25mum. A carbon black reduced to <=0.3 wt% in volatile matter content is used. Polymerization is executed stably in this case, and since the carbon black is located in the inside of the polymer, good insulating property is also attained. This toner is superior in fluidity, and since the particles are of approximately true spheres, and fine and coarse particles are small in amt., the toner is uniformly triboelectrified, and an image free from fog and scattered small spots can be obtained. Since specific resistivity under conditions of being compressed with pressure is as high as >=10<13>OMEGAcm, electrifiability is stable and stable development characteristics can be obtained irrespective of temp. and humidity.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic toner used for developing electrostatic images.

Conventionally, magnetic toner has generally been produced by melt-mixing magnetic powder in a thermoplastic resin, uniformly dispersing the mixture, and then using a pulverizer and a classifier to produce a toner having a desired particle size. Although this method of manufacturing can produce fairly good toners, it does have certain limitations, namely the range of material selection for the toner. For example, the resin colorant dispersion must be sufficiently friable to be pulverized in economically viable manufacturing equipment.

This requirement makes the resin colorant dispersion brittle, so when it is actually pulverized at high speed, particles with a wide range of particle sizes are likely to be formed, and 4.v contains a relatively large proportion of fine particles. The problem is /-1. Furthermore, such highly brittle materials are often further pulverized or powdered when used for development in copying machines and the like. Furthermore, in this method, a conductor such as a magnetic material is exposed on the fractured surface, which may make it difficult to manufacture an insulating toner.

Furthermore, in order to obtain a high-quality black image, a magnetic toner having sufficient black color is required, and for this purpose, it is often desirable to add carpump thick to the toner in addition to the magnetic material. However, since these magnetic materials and carbon black are both conductors, when a toner containing them is produced by a pulverization method, more carbon black is exposed on the fractured surface, resulting in a decrease in layer insulation.

The object of the present invention is to -1- crush D by (Ji
+l: Solve the shortcomings of l・ner, further save labor, and be more versatile! In response to the ever-increasing demand for high-quality imaging with the
The purpose of the present invention is to provide a magnetic toner for developing electrostatic images.

A more specific object 1-1 of the present invention is to provide a toner for developing electrostatic images that is not pulverized in a developing device.

A further object of the present invention is to provide a toner for image development in which a conductor is not exposed on the surface and the static 11 is highly insulating.

Furthermore, the object of the present invention is that the band IIf is stable and uniform, there is no fogging, dusting, etc., and the strength is 4.
The objective is to provide 1 p of I-toner for developing electrostatic images.

In addition to the above, it is an object of the present invention to provide a toner for developing electrostatic images that can provide clear, RF black, and high quality reproduced images.

The toner for developing an electrostatic image of the present invention was developed to achieve the object stated in (-).More specifically, it contains a magnetic material and carbon black, and has a Wardell practical sphericity of 0.95. A toner having a substantially spherical shape of ~i, oo and having an average number Mi of 5 to 25, characterized in that the volatile content contained in the carbon black is 0.3% by weight or less It is.

In other words, in order to eliminate the disadvantages of magnetic toner produced by the double pulverization method, it is desirable to use magnetic toner that is spherical and has a uniform particle size. According to the present inventors, such a spherical toner can be satisfied by having a Wardell practical sphericity of 0.95 to 1.00 and a number average diameter of 5 to 25 #L. It is often preferable to obtain such a spherical toner by a wet dispersion method such as a suspension polymerization method. However, when attempting to obtain a toner containing carbon blank in addition to a magnetic material by, for example, the suspended SM method, polymerization stability is not obtained, and desired physical properties and developability are often not obtained. According to the research conducted by the inventors, it was found that the main cause of this problem lies in carbon black, especially its volatile content. Contains a large amount of aromatic compounds containing oxygen acidic functional groups. If carbon black with a high volatile content is used, the stability of polymerization will be inhibited. Also, carbon black with a high volatile content tends to collect on the surface of the polymer. This decreases the insulating properties of the toner.On the other hand, when using carbon black with a volatile content of 0.3wt.1.1% or more, the carbon black becomes stable and the carbon black Since it is inside the polymer, a toner with good insulation properties can be obtained.

The present invention will be explained in more detail below. In the following description, ``1%'' and ``BRJ'', which represent quantitative ratios, refer to serious injuries unless otherwise specified.

The toner for developing electrostatic images of the present invention is generally obtained by a wet dispersion method or a spray drying method, but is particularly preferably obtained by a suspension polymerization method. For more details,
It is obtained by mixing or dispersing the magnetic material and carbon black with a monomer containing a suitable polymerization initiator, dispersing the resulting slurry in an aqueous dispersion medium, and subjecting it to suspension polymerization.

According to the present invention, the carbon black has a volatile content of 0.
3% or less is used. Here, the volatile content is about 3
It is defined as the ratio of the weight loss to the weight of the original sample when a sample of 50 g is heated at 970° C. for 7 minutes in a platinum crucible.

Such low-volatile carbon black is generally obtained by heating a conventional carbon blank to remove volatile components in an inert gas atmosphere or in vacuum. On this occasion,
Since the oxygen-containing groups on the surface are also removed and the surface is inactivated, the above-mentioned disadvantages in the toner during polymerization are eliminated. This low volatile carbon black is preferably graphitized such as so-called graphon or graphite carbon. An example of a preferred commercially available product is Carbon Black 40° OB y manufactured by Mitsubishi Kasei Corporation. Carbon blank included in i-chi 4, +Ii, ha, 0, 05~l
O%c7) Fjlj enclosure 11 I't Ll'.

The magnetic material may be any material that is magnetized when placed in a magnetic field, such as ferromagnetic metals such as iron, cobalt, and nickel, or alloys and compounds such as macnetite I, hematite, and ferrite I. The particle size is 0.1~2jL
The sieves and enclosures are often used. m like this
The content of 11,1 in the M body powder is preferably 15 to 70% of the toner.

In order to encapsulate the magnetic powder inside the toner and prevent it from being exposed on the toner surface, it is preferable to use fatty acid, fatty acid metal soap, oxidized wax, metal 11 (wax, etc.) together with the m++ powder.

Fatty acid metal soaps are generally represented by M (OOCR)n (where M is a metal, R is an organic group, and n is an integer representing the valence of the metal M). Examples of fatty acid HCOOH include capronic acid, enane l-M, caprylic acid, pelargonic acid, capric acid, undecylenic acid, lauric acid, tridecylic acid, myristic acid, pentadecyl acid, palmitic acid,
Heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lychnoceric acid, cerotic acid, heptacosane, montan, melisinbutyro, lafuselic acid, oleic acid, stearolic acid, arachidonic acid, etc., and fatty acid metal soaps include Preferably, 11 is a combination of these fatty acids and metals such as barium, zinc, calcilyl, aluminum, cadmium, and magnesium.

Examples of oxidized waxes include those with an acid value of 8 (mg K
Examples of metal salt waxes include petrolactam oxides with OH/g) and above, such as calcium and barium 41.

These metal soaps or waxes are magnetic material 1008I
It is preferably used in an amount of 0.2 to 10 parts, particularly 0.6 to 5 parts, based on I.

In addition to or in place of the combination with these fatty acid metal stones, etc., it is also possible to pre-process the magnetic powder with monolithic vinyl such as styrene in order to encapsulate the magnetic powder in the toner particles. preferable.

] The following monomers that should be used in suspension polymerization together with the above-mentioned magnetic material and carbon black can be applied to the present invention.

Styrene, 0-methylstyrene, In-methylstyrene, p-methylstyrene, p-methyl-xystyrene, p
-Phenylstyrene, 11-chlorostyrene, 3.4-
Dichlorostyrene, l)-ethylstyrene, 2,4-dimethylstyrene, p-n-butylstyrene, p-te
Styrene and its derivatives such as rt-butylstyrene, p-11-hexylstyrene, p-n-octylstyrene, p-n-nonylstyrene, p-n-decylstyrene, p-n-dodecylstyrene; ethylene, propylene Ethylenically unsaturated olefins such as , butylene, and isobutylene; vinyl halides such as vinyl 1sueide, vinylidene pentachloride, vinyl bromide, and magnetized vinyl;
Vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate; butymethyl methacrylate, ethyl methacrylate, propyl methacrylate, n-methacrylate
α-methylene aliphatic monomers such as butyl, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylamino methacrylate, ethyl, diethylaminoethyl methacrylate, etc. Carboxylic acid esters; methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-butyl acrylate,
F-decyl acrylate, 2-ethylhexyl acrylate,
Stearyl acrylate, 2-chloroethyl acrylate,
Acrylic esters such as phenyl acrylate; Vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, and vinyl isobutyl ether; Vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, and methyl isopropenyl ketone; N-vinylpyrrole, N
- N-vinyl compounds such as vinylcarbazole, N-vinylindole, and N-vinylpyrrolidone; vinylnaphthalenes; acrylic acid or methacrylic acid derivatives such as acrylonitrile, torsion methacrylate, and acrylamide.

During polymerization, the following crosslinking agent may be present in addition to the monomers listed in -1 to form a crosslinking polymer.

That is, divinylbenzene, divinylnaphthalene, divinyl ether, divinyl sulfone, diethylene glycol dimethacrylate 1., triethylene glycol diacrylate 1., ethylene glycol dimethacrylate,
Polyethylene glycol dimethacrylate-1, diethylene glycol diacrylate, triethylene glycol diacrylate, 1.3-butylene glycol dimethacrylate, 1.6 hexane glycol dimethacrylate, neobentyl glycol dimethacrylate-1, dibropylene glycol Dimethacryle-1, polypropylene glycol dimethacrylate-1, 2.2° bis(4-methacryloxyjethoxyphenyl)propane, 2.2'
Bis(4-acryloxyjethoxyphenyl)propane, trimethylolpropylene Han I. Rimethacrylate 1.
, trimethylolpropane triacrylate tetraacrylate-1., dibromneopentyl glycol dimethacrylate, diallyl phthalate, and the like can be appropriately used.

If a large amount of these crosslinking agents is used, the fixing properties will be poor. In addition, if the number of used parts is small, properties such as blocking resistance and durability required for toner will deteriorate, and during hot roll fixing, some of the toner will not completely adhere to the paper and will stick to the roller surface and be transferred to the next paper. It becomes difficult to prevent the offset phenomenon of metastasis. Therefore, the use of these crosslinking agents is 0.001 relative to the total monomer mass.
-15% (more preferably 0.1-10%) is preferred.

As the polymerization initiator, any suitable polymerization initiator such as azobisisobutyronitrile (AIBN), benzoyl peroxide, methyl ethyl ketone peroxide,
Polymerization can be carried out using isopropyl peroxycarbonate, cumene hydroperoxide, 2,4-dibenzoyl peroxide, lauroyl peroxide, and the like. Generally, about 0.1 to 10% (more preferably 0.5 to 5%) of the total weight of initiator is sufficient.

Suspension polymerization is generally carried out in an aqueous dispersion medium. That is, any suitable stabilizer such as polyvinyl alcohol, gelatin, methyl cellulose, methyl hydroxypropyl cellulose, ethyl cellulose, the sodium salt of carboxymethyl cellulose, polyacrylic acid and their derivatives, starch, gum alginate, zein. , casein, tricalcium phosphate, talc, age. It can be used by incorporating it into a barium acid, bentonite, aluminum hydroxide, ferric hydroxide, titanium hydroxide, or triudate hydroxide phase.

These stabilizers are used in amounts ranging from about 0.1 to 10% by weight to stabilize the dispersion of the monomer mixture in the aqueous I'll phase.

To carry out suspension polymerization, first a polymerization initiator is required.

A monomer system in which magnetic substances, carbon black, monomers, and other additives are uniformly dissolved or dispersed is added to an aqueous phase or continuous phase containing a suspension stabilizer using a conventional IW stirrer or Disperse using a homomixer, homogenizer, etc. Preferably, the IW stirring speed I is such that the monomer droplets have the desired toner particle size, generally less than 30 μl.
After adjusting W and time, the state of C, ff, and Ml. In order to maintain the stability, stirring may be carried out to such an extent that sedimentation of the particles is prevented. Polymerization temperature is 50
Polymerization is carried out at a temperature of 70-90'C or above, generally 70-90'C. After the reaction is completed, the produced toner particles are collected by a suitable method such as washing, filtration, decantation, centrifugation, etc., and dried.

The toner for developing electrostatic images of the present invention is thus obtained as a substantially spherical toner having a Wardell practical sphericity of 0.95 to 1.00 and a number average diameter of 5 to 25 μm.
Here, Wardell's practical sphericity is defined as the diameter of a circle with an area equal to the projected area of the particle, and the B of the particle.
? E1 is expressed as the ratio to the diameter of the smallest circle circumscribing the image, and more specifically, it was measured by the following method. In other words, apply toner on the slide glass.
il'! The toner particles are removed and separated so that individual toner particles do not come into contact with or pile up on the phase lr. These toner particles are transferred onto a CRT screen using a Luxex 450 (1,1 Wood Reculator-9A) at a magnification of 500 using a wJ microscope.
Take a picture at double magnification. Here, in Luzex 450, if each particle exists separately, it is possible to select any particle as self 111 and determine its projected area 1111, so from this, the diameter of a circle with equal area can be calculated. . On the other hand, this CRT screen is photographed as is, and the minimum circle circumscribed to the projected image of the particle is determined by drawing.

Here, 100 toner particles with the above ratio randomly selected
About the item; it '0. L, the -+i average value was calculated and it was determined as "one practical spherical ship of Wardell".The number average diameter is Coulter counter TA-II, aperture diameter 1
00μ, polystyrene standard sample, sample was assayed and 1IllI was determined.

Since the toner produced by the FJ'llA polymerization method according to the present invention is obtained without any pulverization process, brittleness is not necessary.
Generally, the shape is spherical and the particle size distribution is narrow.

In particular, when the Wardell practical sphericity is 0°95 to 1.00,
Toners with a number average diameter of 5 to 25 have excellent motive power, are almost pearl-like, and have little fine powder and coarse powder, so
Frictional charging is uniform, and images with no fog or flicker can be obtained.

In fact, if the sphericity is less than 0.95, fog will be noticeable in the resulting image, if the particle size is less than 5mm, there will be a lot of fine powder and fog will be noticeable, and if it exceeds 25 hiro, there will be a lot of coarse powder and it will cause a lot of dust. The ratio is 1-1, and it is difficult to say that it is a high-quality image.

According to a preferred embodiment of the present invention, the toner is obtained as having a specific resistance value of l Q 100 cm or more under pressure compression. Such a high electrical resistance value is obtained because the magnetic material and carbon black, which are conductors, are contained inside the toner and are not exposed on the surface of the toner particles. Stable development characteristics can be obtained regardless of environmental factors such as humidity. On the other hand, specific resistance ((If i is less than 1Q13Ωcm, it will not be sufficiently charged under high humidity and only a low density image will result11).
Furthermore, fogging is more likely to occur under low humidity conditions. In addition, the specific resistance value in the pressurized compression mode specified in this specification is for an inner diameter of 31 m.
Miyako's toner is inserted into a hard glass cell with a height of approximately 5 mm after compression, and compressed by applying a pressure of 576 kg/cm2 between a stainless steel push rod and a brass base. This is the measurement of the electrical resistance value between and.

Hereinafter, the unreleased 1 will be explained in more detail with reference to Examples.

The mixture was uniformly mixed for about 20 minutes in a container equipped with a homo mixer (manufactured by Tokushu Kogyo Co., Ltd.). During that time, the temperature dropped to 50℃.
It was warm. During this time, the magnetite was uniformly dispersed in the styrene monomer.

30 g of lauroyl peroxide was stirred and mixed into the magnetite-containing styrene monomer. 600g of water with 9.0g of polyvinyl alcohol dissolved at 70℃
and put the above slurry into a homomixer while stirring.
Stirring was carried out at 4000 rpm for 30 minutes to obtain particles of about 10p. This reaction mixture system was stirred with a paddle stirring blade to complete the polymerization. Washed with water, sieved, dried, number average diameter 9.6
(Coulter counter, 100. aperture used), sphericity 0.99, specific resistance () 4 x 10"
A toner of Ωcm was obtained.

This toner can be used on commercially available dry type electronic copying machines. NP-400
Images were created using RH. As a result, it was possible to obtain clear, pure black images with no blur or fog. The image density was 1.6 in solid black areas using a reflection densitometer. Furthermore, toner 1. It satisfied II properties, and was particularly excellent in fluidity and continuous image output IEA durability. In addition, images almost equivalent to those under normal humidity were obtained even under high humidity conditions.

240 g of magnetite (BL-250) grafted with 12 g of styrene, 5 g of carbon black (Mitsubishi Kasei 64000B, volatile content 0.3%), 320
By the same method as in Example I using 8.0 g of styrene and 8.0 g of ethyl methacrylate I, a number average diameter of 9.0 g was obtained.
4g (Coulter counter, ioo, using aperture), sphericity 0.98. Specific resistance if46 x 10”
A toner of Ωcm was obtained.

Apply this toner to a commercially available dry electrophotographic copying machine NP-400RE.
The image output was 91. As a result, a clear, f(black) image was obtained without any dust or fog.

In addition, even under high humidity conditions, no problems were obtained and the image quality was 0.0 image density was determined by a reflection densitometer to be 1.
I got 56.

Support 1” Malein butyroadduct of magnetite (BL-250) 60g and α-o’lz fin (manufactured by Mitsubishi Kasei) 1. .

g and carbon black (Mitsubishi Kasei #4000B)
10g and 80g of styrene, n-butyl methacrylate)・
20g, l-limethylolpropane triacrylate 0
．． 2 g and 2 g of chromium acetylsalicylate 211 were added and uniformly dispersed and mixed using a ball mill.

Thereafter, 3 g of 2,2'-azobis-(2,4-dimethylvaleronitrile) was added and dissolved. In an aqueous phase of 300 g of water to which 3 g of tricalcium phosphate and 5 g of F-decylbenzenesulfonate sodium were added,
The slurry was heated at 5000 r using a TK-homogenizer.
The mixture was added while stirring at a stirring speed of pm+. Thereafter, polymerization was carried out at 60''C for 7 hours to complete the polymerization reaction.

After cooling, filter.

After drying, a toner having a number average diameter of 9.2 μm (using a coulter counter with a 100-diameter aperture), a sphericity of 0°995, and a specific resistance (ri 2 X l' 0 ''ΩCIll) was obtained.

This toner was prepared using a commercially available dry type ('!/true copy aNP-
The images were imaged using 400RH. As a result, a clear, high-quality image with no fog was obtained. In addition, 11 images were obtained even under high humidity conditions, which were the same as under normal humidity conditions.

Claims (1)

[Claims] 1. Substantially bispherical with a Wardell practical sphericity of 0.95 to 1.00, containing a magnetic material and carbon black;
A toner for developing an electrostatic image, wherein the toner has a number average diameter of 5 to 25 pL, and the volatile content contained in the carbon black is 0.3% by weight or less. 2. The persimmon of the patent claim, characterized in that the specific resistance Ida 1 under pressure compression is 101:1Ωcm or more.
The electrostatic image developing toner described in . 3. The toner for developing an electrostatic image according to claim 1 or 2, which is produced by a suspension polymerization method.