JPS60117253A - Electrostatic charge image developing toner - Google Patents

Abstract

PURPOSE: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 rendering the carbon black hydrophobic. 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. When carbon black is made hydrophobic by treating the surface with a Ti coupling agent or silane coupling agent or the like, polymerization is executed stably, and since the carbon black is located in the inside of the polymer, good insulating property is 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 compressed and pressurized conditions 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 it, and then using a pulverizer and a classifier to produce a toner having a desired particle size. Although this manufacturing method can produce fairly good toners, it does have certain limitations, namely the range of toner material selection. For example, for resin colorants, the 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 particle size are likely to be formed, especially when a relatively large amount of fine particles are included. . Furthermore, such highly brittle materials are often subjected to pulverization or powdering 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.

Further, 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 carbon black in addition to the magnetic material. However, since these magnetic materials and carbon blanks are both conductors, I
・When manufacturing -No- by crushing V, the carbon blank is also exposed on the fracture surface, resulting in a 11 with even lower insulation properties.
1〈.

An object of the present invention is to provide a magnetic toner for electrostatic image development that can overcome the drawbacks of the magnetic I-toner due to the pulverized state described in -1- and can also meet the ever-increasing demand for high-quality imaging. There is a particular thing.

A more specific object of the present invention is to provide a toner for developing static images that does not become pulverized in the imager when viewed from a copying machine.

A further object of the present invention is to provide a toner for developing electrostatic images that has high insulation properties and has no conductor exposed on the surface of the toner particles.

Furthermore, in addition to the above, it is an object of the present invention to provide a toner for developing electrostatic images that can provide high-quality, pure black, reproduced images.

The toner for developing electrostatic images of the present invention was developed to achieve the 1-1 objective of -1-\.More specifically, it contains a magnetic material and carbon black, and has Wardell's practical sphericity. is 0.95 to 1.00 and has a spherical shape and a number average diameter of 5 to 25. The carbon blank is hydrophobized carbon black. be.

In other words, in order to eliminate the drawbacks of the magnetic toner produced by the pulverization method described in "-6," it is better to use a magnetic toner with a spherical shape and uniform particle size obtained by a wet method such as the suspension polymerization method. According to Meiji Suekan et al., such spherical toner has a Wardell practical sphericity of 0.95 to 1.00.
This is satisfied when the number average diameter is 5 to 25 mm. However, when trying to obtain a toner containing carbon black in addition to a magnetic material by, for example, a suspension polymerization method, polymerization stability t1 cannot be obtained, and desired physical properties and development +1 cannot be obtained in many cases. According to the research of Mizo et al., the main cause is carbon black, 1,'I
was found to be due to its hydrophilic properties. That is, ordinary carbon black leaves many wood-loving groups such as oxygen-containing acidic functional groups on its surface and is hydrophilic. When such hydrophilic carphone black is used, the stability of polymerization is inhibited. Also, the carbon black of parent wood 1 tends to collect on the surface of the polymer, which reduces the insulating properties of the toner. On the other hand, when using a carbon blank whose surface has been hydrophobized using a titanium coupling agent, a silane coupling agent, etc., the polymerization is stabilized and the carbon black enters the inside of the polymer, resulting in good insulation properties. I・ner who also has 111.

The present invention will be explained in more detail below. In the following description, "1%" and "part" expressing a quantitative ratio are based on the dose unless otherwise specified.

The electrostatic image developing toner of the present invention is generally obtained by a suspension polymerization method. From r+T L <, the magnetic material and carbon black are mixed or dispersed with a monomer containing a suitable polymerization initiator, and the resulting slurry is dispersed in an aqueous dispersion medium, without involving suspension polymerization. It will be done.

According to the present invention, hydrophobically treated carbon black is used as the carbon black. The hydrophobization treatment is performed by treating carbon black with a coupling agent. As the coupling agent, a coupling agent that reacts with an oxygen-containing group, particularly a phenolic hydroxyl group, on the surface of carbon black can be optionally used, but well-known silane coupling agents and titanium coupling agents are preferably used. Specific examples thereof include methyltrimethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltris(2-methoxyethoxy)silane, γ-methacryloxypropyltrimethoxysilane, γ-aminopropyltrimethoxysilane,
N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γglycidoxypropyltrimethoxysilane; isopropyl Triisostearoyl titanate, isopropyl tridodecylbenzenesulfonyl titanate, isopropyl tris(dioctyl pyrophosphate) titanate I, tetraisopropyl bis(dioctyl phosphite) rapeseed-1, tetraoctyl bis(ditridecyl phosphite) ticnate, isopropyl trioctanoyl titanate I, isopropyl dimethacrylylisostearoyl natane I, isopropyl isostearoyl diacryl titanate, isoprobyl (dioctyl phosphate) titanate 1, isoprobyl (N-aminoethyl-aminoethyl) titanate I., dicumyl phenyloxyacetate I. titanate I., diisostearoyl ethylene titanate, His(dioctylpyrophosphini I.) ethylene natanate, His(dioctylpyrophosphini I.) oxyacetate titanate, Tet( 2,2
Examples include diallyloxymethyl-1-butyl)bis(di-I.lysosyl)phosphite-I.titanate.

The carbon black that should be treated with the above-mentioned cambling agent is a basic carbon black that is considered to be an aggregate of carbonaceous crystals obtained by burning or thermally decomposing hydrocarbons or carbon-containing substances in an oxygen-deficient condition. Specifically, any carbon black can be used. Examples of preferred commercially available products include MA-8 and M manufactured by Mitsubishi Kasei Corporation.
A-11, MA-100, 50, 55, 40 (B), 4
5(B); Made by Columbia Fist Carbon, Royal 5p
ectra, Neo 5pectra Mark
III, Raven 50, Raven150,
Raven 15, etc.

As a method for treating carbon black with a coupling agent, either a dry method or a wet method can be adopted, and a wide range of treatment methods can be used. For example, carbon black and an appropriate amount (preferably 0.1
-10%) of a camping agent and dry mixing, or a method is used in which a coupling agent is dissolved in a suitable solvent, carbon black is added and mixed, and the solvent is removed.

The content of hydrophobized carbon black in the toner is preferably in the range of 0.05 to 10 parts.

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 grain sizes of alloys and compounds such as magnetite, hematite, and ferrite I. is 0.1 to 211. Those within the range of are preferably used. The initial content of such magnetic 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 surface of the toner, it is preferable to use fatty acids, fatty acid metal soaps, oxidized wax, metal wax, etc. together with the magnetic powder.

Fatty acid metal soaps are generally represented by M (OOCR)n (where M is a metal, R is an organic group, and ■ is an integer representing the value of the metal M). As fatty acid It COOII,
For example, caproic acid, enane I acid, caprylic acid, pelargonic acid, capric acid, undecylenic acid, lauric acid, I
・Lysosylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, hehenic acid, lignoceric acid, cerotic acid, heftacosane, montanic acid, melisic acid, lafcelic acid, oleic acid, stearic acid Examples include roll acid and arachidonic acid, and salts of these fatty acids with metals such as barium, zinc, calcium, aluminum, cadmium, and magnesium are preferably used as fatty acid metal soaps.

An example of an oxidized wax is an acid value of 8 (mgKOH).
/g) Examples of petrolactam oxides containing metal oxides include calcium, barium j1, and the like.

These metal soaps or waxes are preferably used in an amount of 0.2 to 10 parts, particularly 0.5 to 5 parts, per 100 parts of the magnetic material.

Furthermore, instead of or in addition to the combination with these fatty acid metal soaps, it is also preferable to graft the magnetic powder with a vinyl monomer such as styrene in advance in order to encapsulate the magnetic powder in the toner particles. .

%m together with the above-mentioned magnetic material and carbon black
The following seven tools can be applied to the present invention.

Styrene, 0-methylstyrene, l-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3.4-dichlorostyrene, P-ethylstyrene, 2.4- Dimethylstyrene, p-n-butylstyrene, p-n-butylstyrene, p-n-hexylstyrene, p-11-offnalstyrene, p-n-7nylstyrene, p-n-
Styrene and its derivatives such as decylstyrene and p-n-dodecylstyrene; ethylenically unsaturated monoj''lefins such as ethylene, brocobylene, butylene and isobutylene; vinyl chloride, vinylithine II, odorized vinyl, magnetization /\Lokenized vinyls such as vinyl; vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzate; mebule methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, Methafurylumi n-octyl, methacryl norllltA1 decyl, methacryl ugly-2
- ethylhexyl, stearyl methacrylate, methacrylic butylene, dimethylamine ethyl methacrylate,
α-methylene aliphatic monocarboxylic esters such as diethylaminoethyl methacrylate; methyl acrylate;
Acrylic acids such as ethyl acrylate, mn-butyl acrylate, isobutyl acrylate, propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, and phenyl acrylate. Esters; 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 impropenyl ketone; ~N-vinyl compounds such as rubinylindole N-vinylpyrrolidone; vinylnaphthalenes; acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, and acrylamide;

During polymerization, a crosslinking agent such as a primary one may be present together with the above-mentioned monomers to form a crosslinked polymer.

That is, divinylbenzene, dichlorostyrene, divinyl ether, divinyl sulpon, diethylene glycol dimethacrylate-1, triethylene glycol diacrylamicol dimethacrylate, polyethylene glycol dimethacrylate, diethylene glycol diacrylate,
Triethylene glycol diacrylate, 1. ．． 3-butylene glycol dimethacrylate, 1.6 hexane glycol dimethacrylate I, neopentyl glycol dimethacrylate I, dibropylene glycol dimethacrylate I, polypropylene glycol dimethacrylate I/
-1,2,2'bis(4-methacryloxyjethoxyphenyl)propane, 2,2'his(4-acryloxyjethoxyphenyl)propane, 1rimedylolpropane trimethacrylate, trimethylolpropane triacrylate -), tetramethylolmethanetetraacrylate, dibromneobentylglycoldimethacrylate, and phthalate diallyl, etc., can be used as appropriate.

When these crosslinking agents are used in large amounts, the fixing properties are poor. Also, if the amount used 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 f11 of these crosslinking agents is 0.001 per thousand
It is preferable to use it at ~15% (more preferably 0.1~10%).

As the polymerization initiator, any suitable polymerization initiator may be used, such as azobisisobutyronitrile (AIBN), benzoyl peroxytite, methyl ethyl ketone peroxide,
Monomer polymerization can be carried out using inpropyl peroxycarbonate, cumene hydroperoxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide, and the like. Generally, it is about 0.1-10% (more preferably 0.1-10% of the total weight of the nanatsuma).
5-5%) of initiator is sufficient.

The suspension 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, sodium salt of carboxymethyl cellulose, polyacrylic acid and their 431, starch, gum algin M
IJJ, sein, casein, tricalcium phosphate, talc, sulfur helium J1, bentonite, aluminum hydroxide 1, ferric hydroxide, titanium hydroxide, hydroxide 1 liu 1
1, etc. can be used by incorporating them into the water↑11 phase.

These stabilizers are li! l! 1, 1, iff stabilizes the dispersion of a mixture of -1, ligands, etc. during the continuation phase.
Preferably, it is used within the range of about 0.1-10%.

To carry out suspension polymerization, first a Togane initiator, a magnetic material,
Carbon black, carbon black, and other additives are uniformly dissolved or made into one molecule by adding a single product into an aqueous phase containing a suspension stabilizer, that is, a continuous phase, using a conventional stirrer, homomixer, or homogenizer. etc. to disperse it.

Preferably, the medium droplets have a desired toner particle size,
In general, the stirring speed and time are adjusted so that the particles have a size of 30 mm or less, and after that, the stirring is controlled to an extent that prevents sedimentation of the particles so that the dispersion stabilizer maintains the same state of f&i. Just do it. The polymerization temperature is set at 50 DEG C. or higher, generally 70 to 90'O. After the reaction is completed, the i.ner particles produced are recovered by washing, filtration, decantation, appropriate fogging such as centrifugation, and dried.

In this way, the I-ner for electrostatic image development of the present invention can be prepared by:
The toner can be 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. Here, Wardell's practical sphericity is a value expressed as the ratio of the diameter of a circle with an area equal to the projected area of the target particle to the diameter of the smallest circle circumscribing the projected image of the target particle, and is more specifically Specifically, it was measured by the following method. That is, an appropriate amount of toner is placed on a slide glass and dispersed so that individual toner particles do not come into contact with each other or overlap. These I-ner particles are transformed into Luzenkus 4
50CIJ wood leggi, made by Rater), CRT screen-
1-: Image is taken using a microscope (J2 ratio: 500x). Here, Luzex 450 allows you to freely select any particle and measure its projected area, as long as each particle exists separately. From this, the diameter of a circle with an equal area can be calculated by 1.Meanwhile, take a photograph of this CRT screen as it is and find the diameter of the smallest circle circumscribing the projected image of the particle by drawing.Here, 1- For 100 toner particles whose distribution is chosen as rung I, +l 'fly,
L, the average value was calculated as [Wardell's practical sphericity], and the number average diameter was determined by Coulter counter TV.
The fill was determined using p e II with aperch + f*l (10 g) and assayed with a polystyrene standard sample.

Since the L-ner produced by the suspension polymerization method of the present invention can be obtained without any pulverization process, 1-brittleness is not inevitable, and it is generally spherical in shape and has a narrow particle size distribution. In particular, toners with a Wardell practical sphericity of 0°95 to 1.00 and a number average diameter of 5 to 25° have excellent fluidity, are almost pearl-like, and have little fine powder and coarse powder. , images with uniform triboelectric charging and no fogging or blurring can be obtained. In fact, if the sphericity is less than 0.95, there will be fog in the image obtained.If the particle size is less than 5 IL, there will be a lot of fine powder, and if the fog is 1.1 or more, and if it exceeds 25 IL, it will be coarse powder. Because of the large number of images, there are 11 irregularities, making it difficult to say that it is a high-quality image.

According to a preferred embodiment of the present invention, the toner has a specific resistance value of 10 13 Ωcm or more under pressure compression. Such a high specific resistance value is obtained because the magnetic material and carbon blank, 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 requirements. On the other hand, if the resistivity value is less than 1013 Ωcm, charging will not be sufficient under high humidity conditions, and only one low-density image will be printed, and fogging will easily occur under low humidity conditions. In addition, the specific resistance Ida 1 under pressure compression specified in this specification is obtained by inserting an amount of I.na into a hard glass cell with an inner diameter of 31 mm so that the height after compression is approximately 5 mm, and then forming a stainless steel cell. A pressure of 57.6 kg/cm2 was applied between a steel push rod and a brass stand, and the material was compressed.
The specific resistance value between the push rod and the gap was measured.

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

20g of carbon black (manufactured by Mitsubishi Kasei, MA-8),
100 m of 1% aqueous solution of methyltrime I xysilane
After mixing and stirring at room temperature for 6 hours, the product was filtered, washed with water, and dried to obtain hydrophobized carbon black. Using this hydrophobized carbon black, a toner having the following composition was produced.

The mixture was poured into a container equipped with a TK-Homo mixer (manufactured by Tokushu Kogyo Co., Ltd.) and mixed uniformly for about 20 minutes, during which time the temperature was raised to 50°C. During this time, the magnetite was uniformly dispersed in the styrene monomer.

30 g of lauroyl peroxide was stirred into the 2E-1 gnetite-containing styrene monomer. 9
600 g of water in which 0 g of polyvinyl alcohol was dissolved was maintained at 70°C, and the slurry described above was added to the homomixer while stirring, and the slurry was stirred at 4000 rpm for 30 minutes.
particles were obtained. This reaction mixture system was stirred with a paddle stirring blade to complete the polymerization.

The toner was washed with water, filtered, and dried to obtain a toner having a number average diameter of 9.6 JL (using a Coulter counter with a 1007 t aperture), a sphericity of 0.99, and a specific resistance value of 4 x 10100 cm.

This i-ner can be used with a commercially available dry type electrophotographic copying machine NP-400.
Images were created using RH. As a result, I was able to get a clear, pitch-black image with no flickering or fog. The image density was 1.6 in the solid black area based on the reflection density. Furthermore, the toner properties were satisfied, and the fluidity and continuous image formation 1 durability were particularly excellent. Also, even under high humidity conditions, images almost as good as those under normal humidity conditions were obtained.

This factory 1” Graph I treated magnetite with styrene (BL-
200), 240g and 9 carbon black (manufactured by Niuryo Kasei, MA-11) which was hydrophobized in the same manner as in Example 1.
In the same manner as in Example 1, using 5 g of styrene, 320 g of styrene, and 8.0 g of ethyl methacrylate I.
Number of pieces -) i average diameter 9.4 end (Coulter counter, l
A toner with a sphericity of 0.98 and a specific resistance value of 6 X l O 1000 m was obtained.

This toner was transferred to a commercially available dry electronic printer, KK Copy NP-40.
Image extraction was performed using 0RH. As a result, a clear, pure black image was obtained with no blur or fog.

Furthermore, excellent image quality was obtained without any problems even under high humidity conditions. Image density is 1 due to reflection density + l in solid black area.
．． I got 56.

Length i [Carbon black MA-11 (manufactured by Mitsubishi Kasei, MA-11
) was put into 100 mL of a 2% aqueous solution of isopropyl triisostearoyl rapeseed 1. After mixing and stirring at room temperature for 6 hours, the product was filtered, washed with water, and dried in vacuum to make it hydrophobic. Carbon black was obtained.

10g of this hydrophobized carbon black and magnetite (
BL-250) 60g, alpha-olefin maleic acid additive (manufactured by Mitsubishi Kasei) 1g, styrene 80g, n-butyl methacrylate 20g, trimethylolpropane triacrylate 2g, and acetylsalicylic acid chromium complex 2g. The mixture was added and uniformly dispersed and mixed using a ball mill.

Thereafter, 3 g of 2,2-7 sobisu(2,4-dimethylvaleronitrile) was added and dissolved. The above slurry was poured into an aqueous phase of 300 g of water to which 3 g of Rin Uzo Caljoux 1 and 0.05 g of F-Tesylbenzenesulfonate I.Lium were added while stirring at a stirring speed of TK-Pomosinizer-5000 rpm + w. . Then at 60°C 7
1+: Polymerization occurred during the time period, and the polymerization reaction was completed. After cooling,
1 filtration, dried, average number of pieces 9.2 l (Coulter counter, io.

k aperture), sphericity 0,995, specific resistance value 2 x 10 IsΩcmcy) l·ner was 111.

I applied this toner to Ichilli's dry electronics "Q Shinsosha 4% N"
Images were extracted using F-400RE. That mu1. A pure black image with clear surface quality and no fog was obtained. Also high v
Even under U, the image was the same as under normal humidity.

Claims (1)

[Scope of Claims] 1. A toner containing a magnetic substance and carbon black, having a commercially purchased spherical shape with a Wardell practical sphericity of 0.95 to 1°oo, and a number average diameter of 5 to 25 l, 4. The carbon black is hydrophobized carbon black. A toner for developing electrostatic images having +r characteristics. 2. Specific resistance under pressure compression is l Q 13ΩCm
Claim 11 Claim 1 is characterized in that:
The toner for developing an electrostatic image described in jf+. 3. The toner for developing an electrostatic image as set forth in Claim 1JJ1 or 2"fl, which is produced by a suspension polymerization method.