JPS59218459A - Toner for developing electrostatic charge image - Google Patents

Abstract

PURPOSE:To improve the sharpness of an image by using styrenes and acrylic acid esters or methacrylic acid esters as essential resin components. CONSTITUTION:The number average grain size of a toner of which Wadell practical spheroidicity psiW is 9.95-1.00 is 5-25mum. Such toner has the crosslinking structure of 0.05-90wt% gel content and contains 60-95pts. styrene and 5-40pts.wt. acrylic acid ester or methacrylic acid ester as essential resin components. if the Wadell practical spheroidicity is <=0.95, the spheroidicity is equal to shapeless, thus resulting in nonuniform frictional electrostatic charging and deteriorated fluidity. If the number average grain size is <=5mum, the fluidity is poor, thus having an easy tendency to a photographic fog and deteriorated developability. If said size is >=25mum, the square reproducibility of the fine lines of the image is deteriorated. When the gel content or styrene exceeds the above- mentioned range, the elevation of a fixing temp., etc. arise. The sharpness of the image is improved by using the toner compounded in the above-mentioned way.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a toner for developing electrostatic images used in electrophotography, electrostatic printing, magnetic recording, and the like.

Conventionally, toners have generally been melt-mixed in thermoplastic resins, uniformly dispersed, cooled, and then passed through a pulverizer and classifier to produce toners having a desired particle size. Although this manufacturing method can produce fairly good toners, it does have certain limitations.

That is, the toner obtained using the pulverization method must have some brittleness so that the material is somewhat susceptible to pulverization. However, those that are highly brittle are
The toner becomes too fine and the fine powder must be cut in order to obtain a toner with an appropriate particle size distribution, which increases costs. Further, it may be further pulverized in the developing device of a copying machine. Furthermore, when a material with a low melting point or a material with pressure fixing properties is used to improve heat fixability, a fusion phenomenon occurs in a crushing device or a classification device, and continuous production may not be possible.

Other requirements for the toner are that it has triboelectric properties suitable for development, that it forms an excellent image, that there is no change in performance when left unused, that it does not solidify (blocking, etc.), and that it has suitable heat or pressure fixation. Examples include having physical properties and not contaminating the surface of the photoreceptor. Particularly in fixing, an offset phenomenon occurs in which toner adheres to the fixing roller during fixing and is retransferred onto the next copy paper.

The roller that comes into contact with the toner image usually has at least a surface layer formed of silicone rubber or fluororesin, which has good releasability, but in order to prevent offset and prevent fatigue on the roller surface, There is also a method of applying mold release oil such as silicone oil. However, the method of applying oil has problems such as the provision of an oil application system which complicates the fixing device and the evaporation of the oil causing discomfort to the user. Therefore, it is not preferable to try to prevent offset by applying oil; rather, it is currently desired to develop a toner with good offset resistance over a wide fixing temperature range.

In order to solve the fixing offset problem mentioned above,
It is conceivable to use a resin with a cylindrical molecular weight or a cross-linked resin, but in the conventional method, first, when coloring materials and other additives are heat-kneaded into the resin, very high heat is applied. Rather than requiring a large amount of energy9, even if you manage to heat knead it, a very large share is required, which causes the resin molecules to break, resulting in a phenomenon in which the molecules are reduced or the crosslinks are broken. These toners will not be able to exhibit sufficient FNM offset properties.Dad, these hot kneaded materials are extremely hard and require high energy to pulverize them and make them into toner sizes. .

Furthermore, toner produced by the conventional pulverization method is
Since the grains have different shapes and are amorphous, it is thought that the triboelectrification characteristics of each grain are different, and the fluidity is also poor, which is thought to cause variations in developability.

Spherical toners have been proposed in order to overcome the various defects that occur in toners obtained by these pulverization methods. For example, the spray method has been known for a long time.

However, this method involves melting the resin with heat or dissolving it in a solvent, spraying it out in a mist form from a nozzle, and then cooling or drying it to obtain toner. Dissolved in 1'J'l; L
Therefore, it is impossible to obtain a toner that satisfies the above-mentioned drawback of fixing offset property.

Among the various spheroidization methods, suspension polymerization is a method for obtaining particles that contain a dull component and have a particle size suitable as a donor. With this method, it is possible to create a toner that is practically spherical and also contains a chelate component, which satisfies both developability and fixing properties. However, if the degree of crosslinking of the toner is simply increased, the offset property improves, but the fixing temperature tends to be low, making it difficult to fix9. There has to be a balance.

Alternatively, it may be possible to obtain a toner by copolymerizing a monomer with a lower glass transition temperature Tg to lower the fixing temperature, but in this case, blocking may occur. But 1. L, energy saving constant, that is, for example, J
9. It fixes at temperatures as low as 9, and furthermore, it does not cause an offset phenomenon over a wide operating temperature range from low to high temperatures.

Furthermore, it is becoming increasingly necessary to have even better blocking characteristics.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a toner for developing electrostatic images that has better fixing characteristics, that is, has a low fixing temperature and does not cause an offset phenomenon over a wide temperature range.

A further object of the present invention is to provide a toner for developing electrostatic images with excellent developability.

A further object of the present invention is to provide a toner for developing electrostatic images with excellent blocking properties.

A further object of the present invention is to provide an electrostatic image developing toner with excellent fluidity.

That is, the present invention provides a toner having a practically spherical shape with Wadell's practical sphericity vw of 0.95 to 1.00 and a number average particle size of 5 to 25 μm, and a glu content of 0.05 wt% to 9. The toner for developing an electrostatic image as described above is characterized in that it has a crosslinked structure of Q wt candy, and contains 5 to 40 parts by weight of Sunalene 660 to 95 and acrylic acid or methacrylic acid ester as the main resin component. The chain is one that can achieve the purpose.

According to a preferred embodiment of the present invention, suspension M is a toner for developing electrostatic images produced by a method.

The Wardell's practical sphericity 1w mentioned here is the value expressed by the Wardell's practical sphericity γ7.

In addition, the number average diameter is determined by Coulter Counter Tyzo (Typ.
e) II. It is verified and measured by calibration of a styrene standard sample using an aperture diameter of 100μ.

Furthermore, the glu content is the proportion of a portion of a polymer that has been crosslinked and is insoluble in a solvent, and can be used as a type of indicator to express the degree of crosslinking of a highly crosslinked polymer. Glue content is defined by the value measured as follows. That is, a certain weight (Wlg) of the polymer was weighed out, and the soluble IjC content in the nail shaft was removed with a solvent using a Soxhlet extractor using a G-3 glass filter. After drying, weigh the remaining sample (W2.). Real content is W2//W1×
Calculated as 100 (chi). As such a solvent, a nonpolar solvent such as benzene, toluene and tetrahydrofuran is preferable.

Suspension polymerization is a method in which, for example, heavy monomers, colorants, initiators, and other additives are suspended in water and polymerized in the presence of a dispersion stabilizer to obtain particles with uniform diameters. It is something.

In the case of the present invention, a crosslinking agent may be added during polymerization to obtain a crosslinked polymer, or the crosslinked polymer may be dispersed and mixed in a heavy single mass.

In the present invention, if the Wardell practical sphericity is 0.95 or less, the shape is substantially amorphous, triboelectric charging becomes uneven, fluidity decreases, and developability deteriorates. It's not small.

Furthermore, if the number average particle diameter is less than 5 μm, the fluidity becomes poor and capriulation is likely to occur, resulting in poor developability, which is not preferable. Moreover, if it is 25 μm or more, the image performance during development such as poor image reproducibility in fine lines is undesirable.

Further, if the glu content is less than 0.05 wt%, an offset phenomenon occurs, and if it is more than 90 wt%, the fixing temperature becomes high, which is a practical problem. However, it is preferably 5 to 85 wt91i.

Furthermore, if styrene is less than 60 wt% in the binder resin, an offset phenomenon tends to occur in the fixing temperature range.
If it is 5 wt% or more, it is difficult to lower the fixing amount. Furthermore, if the amount of acrylic ester or methacrylic ester in the binder resin is less than 5 wt%, it is difficult to lower the fixing temperature, and if it is more than 40 wt%, offset phenomenon tends to occur and the blocking performance deteriorates. This problem arises.

As the styrene used in the present invention, styrene derivatives can also be used. For example, styrene, 0-methylstyrene, P-methylstyrene, 2,4-methylstyrene, P-n-butylstyrene, P-tert-butylstyrene, P-n-dodecylstyrene, P-chlorostyrene, P-7 Styrenes such as enylstyrene.

Examples of acrylic esters include methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, and n-acrylate.
- Acrylic acid rust conductors such as octyl, dodecyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, and methyl α-chloroacrylate.

Examples of methacrylic esters include methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, and methacrylate. α-Methylene aliphatic monocarboxylic acid such as stearyl acid, phenyl methacrylate, zomethylaminoethyl methacrylate, ethyl aminoethyl methacrylate, etc. Examples include phosphoric acid esters, methacrylic acid derivatives, and the like.

As a crosslinking agent, - a compound having two or more double bonds in the molecule, such as divinylbenzene, zovinylnaphthalene, divinyl ether, divinyl sulfonate, zoethylene glycol some methacrylate, triethylene glycol dimethacrylate, ethylene glycol; Dimethacrylate, polyethylene glycol dimethacrylate, diethylene glycol noacrylate, triethylene glycol diacrylate, 1.3 butylene glycol dimethacrylate, 1.6 hexane glycol dimethacrylate, neopentyl glycol dimethacrylate, zozolobylene glycol dimethacrylate, polyethylene glycol Dimethacrylate, 212'his(4-methacryloxysoethoxyphenyl)propane, 2,2'bis(
4-Acryloxyshedoxyphenyl)propane, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, tetramethylolmethanetetraacrylate, cybromneopentyl glycol dimethacrylate, allyl phthalate, 2,6-noacrylphenol, sialylcarbyl Nor, etc. can be used as appropriate.

Polymerization initiators are generally compounds that generate radicals when decomposed by heat or light, such as 2-2'-azobisisobutyronitrile, 2-
Examples include 2'-azobispropionitrile, 2-2'-azobisvaleronitrile, and 2,2'-7sobis-(2,4-trimethylvaleronitrile).

Examples of organic peroxides include benzoyl peroxide, nuclear-substituted benzoyl peroxide, lauroyl peroxide, acetyl peroxide, keymen hydroperoxide, and the like.

Examples of azo and noazo compounds include diazoaminobenzene and azothioether.

Examples of sulfins include aromatic sulfinic acids.

The suspension stabilizer used in the present invention includes a poorly soluble inorganic compound in the form of fine powder, such as BaSO41CaSO4゜Mg
cos 1BaCOs l c&co3. ” ca5(
po4)z, poorly soluble salts, diatomaceous earth, talc,
Inorganic polymers such as silicic acid, clay, talc, metal oxide powders, water-soluble polymers such as polyvinyl alcohol, gelatin, starch, methyl cellulose, ethyl cellulose,
Examples include oxymethyl cellulose, polyacrylic acid and their salts, alginates, etc. These suspension stabilizers are usually used in an amount of 0.1 to 10% by weight.

Further, a surfactant may be used in an amount of 0.00 to 0.1% by weight for fine dispersion of the resolvable fine powder inorganic compound.

Surfactants used for such purposes include, for example, sodium dodecylbenzene sulfonate, sodium allyl-alkyl polyether sulfonate,
Anionic activators such as sodium oleate, nonionic activators such as polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, etc. are commonly used.Also, as dyes and pigments used in the present invention, commonly known dyes and pigments are used. can be used. Furthermore, carbon black magnetic material can also be used.

Furthermore, generally known crosslinked polymers can be used in the present invention. For example, polyester obtained by crosslinking a vinyl polymer, a styrene-butadiene crosslinked polymer, an ionomer, and the like can be used as appropriate. In this case, it is particularly preferable to use it after pulverizing it.

Further, the polymerizable monomer used in the present invention may contain an uncrosslinked M polymer or copolymer.

In addition, monomers that are easily soluble in water cause emulsion polymerization in water at the same time, and the resulting suspension polymer is contaminated with small emulsion polymer particles, so water-soluble inhibitors such as copper salts are added to prevent emulsion polymerization in the aqueous phase. It's also good.

Additionally, glycerin, glycol, etc. may be added to the water in order to increase the viscosity of the medium and prevent particles from coalescing.

Also, to reduce the solubility of easily soluble monomers in water, N
It is also effective to use salts such as a(J*KCI*Na2SO4.

The suspension method involves adding a monomer system in which the polymerization initiator, monomers, and if necessary colorants and additives are uniformly dissolved or dispersed, into an aqueous phase containing a suspended stabilizer, that is, a continuous phase, as usual. Disperse in a stirrer, homomixer, homogenizer, etc. The agitation speed is such that the monomer droplets have the desired toner particle size, typically 30 μm or less in size;
After adjusting the time, stirring may be carried out to such an extent that sedimentation of the particles is prevented, so that the action of the dispersion stabilizer is maintained.

The polymerization temperature is 50°C or higher, generally 70°C to 90°C. After the reaction is completed, the produced toner particles are recovered by C9 using a suitable method such as washing, filtration, decantation, centrifugation, etc., and dried.

All known methods can be used to develop this toner. For example, two-component development methods such as cascade method, magnetic brush method, and microtoning method; one-component development methods containing magnetic materials such as conductive component development method, insulating component development method, jumping development method, and imaging method. Powder cloud method and fur brush method; Non-magnetic component development method in which toner is held on a toner carrier by electrostatic force and transported to a developing section for development.

Example 1 The mixture was mixed uniformly for about 5 minutes in a container equipped with a high shear mixing device such as Homomixer (manufactured by Tokushu Kogyo Co., Ltd.). During this time, the temperature was maintained at 70°C. Disperse 2g of polyvinyl alcohol in 800g of water using the homomixer described above,
It was kept at 70°C. The above slurry was added to this system under stirring using a homomixer, and the slurry was stirred at about 400 rpm for about 40 minutes. Thereafter, this reaction mixture system was stirred with paddle blade stirring to complete the polymerization. Washed with water, filtered, dried, Coulter counter type ■, aperture diameter 100μ
When the particle size was measured, the number average particle size was 10.5 μm.
I got it. When the glu content of this toner was measured using tetrahydrofuran, the glu content was found to be 5.
It was 0 wt%. This toner was substantially spherical and had a Wardell practical sphericity of between 0.95 and 1.0. This toner and iron powder carrier 250/400 (Japanese iron powder) were mixed at a weight ratio of 10:100 and used as a developer.
When the image was produced using NP-8500, a good image was obtained which was sharp and free from blur. Further, during fixing, there was no offset phenomenon at all, and even if the set temperature was lowered by 10°C than before, sufficient fixing was achieved. Further, a blocking test was conducted at 50° C. for about one week, but no blocking occurred and good fluidity was exhibited.

Comparative Example 1 Novinylbenzene was removed using the recipe of Example 1, and Example 1
A toner was created in the same way. This toner is
The number average particle diameter was 10.2 μm as measured by a counter.

It can be considered that the particle size is the same as in Example 1. Glue content is 0wt%. This toner was substantially spherical and had a Wardell practical sphericity of between 0.95 and 1.0.

When image printing was performed using this toner in the same manner as in Example 1,
An image similar to that of Example 1 was obtained. However, during fixing, an offset phenomenon occurred at all temperatures from 100° C. to 200° C., making it completely impractical.

Example 2 was mixed in the same manner as in Example 1 to obtain a slurry. In the same manner as in Example 1, 1 (l) of CaC05 was added to 80011 of water and stirred at about 4000 rpm for about 50 minutes.

This time series was kept at 60°C. Thereafter, the temperature was maintained at about 60° C. with paddle blade stirring, and the polymerization was completed by stirring.

CaC05 was removed by dilute acid using a conventional method, followed by washing with water, filtering, and drying to obtain a toner. When this was measured in the same manner as in Example 1, the number average particle size was 9.5 μm (1 glucontin).
62 wt% Wardell's practical sphericity is 0.95-1.
It was between 0. This toner and iron powder Gearia 250
/400 (Japanese Iron Powder) was mixed at an M ratio of 10:100 to prepare a developer, and a J rainbow image was created on NP-5500. The image was sharp and good. In addition, there was no offset phenomenon at all during fixing, and even when the set temperature was lowered by 10 degrees Celsius, the fixing was sufficient.Furthermore, a blocking test was conducted at 50 degrees Celsius for about a week, but there were no problems and good flow was observed. Show your sexuality.

Comparative Example 2 A toner was prepared in the same manner as in Example 2 except that trimethylolpropane triacrylate was adjusted to 51% according to the formulation of Example 2. This toner had a number average particle size of 9.8 μm.

Glue content was 95 wt%, and Wardell's practical sphericity was between 0.95 and 1.0. Image printing was performed using this toner in the same manner as in Example 2. The resulting image was the same as in Example 2, but even though the set temperature was raised by 30° C., it was hardly fixed and could not be put to practical use at all.

Claims (1)

[Claims] 1 17-tel cQ practical sphericity 'w is 0.95 to 1.0
In a toner with a practical spherical shape and a number average particle size of 5 to 25 μm, the dull content is 0.05 wt% to 90 wt.
% crosslinked structure, 60 to 95 parts by weight of styrene and 5 parts of acrylic ester or methacrylic ester.
A toner for developing an electrostatic image, characterized in that the main resin component is ~40 fi parts. 2. The toner for developing an electrostatic image according to claim 1, which is produced by a suspension polymerization method.