JPH0810343B2 - Toner for electrostatic image development - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a toner for developing an electrostatic charge image in electrophotography or the like, and more particularly to a toner having improved heat roller fixing performance and electrostatic charge image development performance.

[Background of the Invention]

Conventionally, as the electrophotographic method, a number of methods are known as described in U.S. Pat.No. 2,297,691, Japanese Patent Publication No. 42-23910 and Japanese Patent Publication No. 43-24748. An electric latent image is formed on the photoconductor by various means using a conductive substance, then the latent image is developed with toner, and the toner image is transferred to a transfer material such as paper as necessary. After that, the toner is fixed by heating, pressure, heating and pressurizing, solvent vapor or the like to obtain a copy, and the toner remaining on the photoreceptor without being transferred is cleaned by various methods, and the above steps are repeated.

In recent years, such a copying apparatus is used not only as a general purpose copying machine for copying original documents but also for copying high-definition images such as digital printers or graphic designs as the output of a computer. I started.

Therefore, higher reliability has been rigorously pursued, and accordingly, the performance required for the toner has become higher, and if the performance improvement of the toner cannot be achieved, a better machine cannot be established.

By the way, the most important performances required for toners in digital printers and copying of high-definition images are fine line fixing performance and development reproducibility.

Regarding the fixing process, various methods and devices have been developed, but the most popular method at present is a pressure heating method using a heat roller.

The pressure heating method using a heating roller performs fixing by allowing the toner image surface of a sheet to be fixed to pass through the surface of a heat roller having a surface formed of a material having releasability with respect to toner while contacting the surface under pressure. . In this method, since the surface of the heat roller and the toner image on the sheet to be fixed are brought into contact with each other under pressure, the thermal efficiency at the time of fusing the toner image on the sheet to be fixed is extremely good, and quick fixing is possible. It is possible and very effective in a high speed electrophotographic copying machine. However, in the above method, since the surface of the heat roller and the toner image are in contact with each other in a molten state under pressure, a part of the toner image is attached to and transferred to the surface of the fixing roller, and this is transferred again to the next sheet to be fixed, so-called. Offset development may occur and stain the fixed sheet. Preventing toner from adhering to the surface of the heat fixing roller is one of the essential conditions of the heat roller fixing method.

On the other hand, in the latent image portion of the precision image, the lines of electric force are concentrated at the boundary between the exposed portion and the non-exposed portion, and the surface potential of the photoconductor apparently rises. Especially in digital printers, the latent image is composed of binary basic pixels that are ON-OFF.
The concentration of electric lines of force is large at the boundary between the exposed portion and the non-exposed portion, and the toner amount per unit area developed into a line latent image composed of basic pixels in the developing step is the toner on a normal analog image. More than quantity. Therefore, in the fixing of such an image, the present situation is that a toner having a good fixing property and a good offset property is required more than ever.

Further, it is used as a printer with a copy amount 3 to 5 times that of a copying machine of the same level, and at the same time, high durability of development and high image stability are required.

As a technique relating to the improvement of the binder resin of a toner, for example, a toner using a crosslinked polymer as a binder resin has been proposed in, for example, Japanese Patent Publication No. 51-23354.
If this method is followed, it will be effective in improving the offset resistance and anti-sticking property, but on the other hand, if the cross-linking degree is increased, the fixing point will rise, and the fixing temperature will be low enough to provide good offset and anti-sticking properties. However, the one having sufficient fixing characteristics has not been obtained. Generally, in order to improve the fixing property, it is necessary to lower the softening point by lowering the molecular weight of the binder resin, which is contrary to the measures for improving the offset resistance, and in order to achieve the low softening point. Inevitably, the glass transition point of the resin is lowered and the toner is blocked during storage, which is not preferable.

Further, regarding a toner blended with a low molecular weight polymer and a crosslinked polymer, for example, JP-A-58-86558 proposes a toner containing a low molecular weight polymer and an infusible high molecular weight polymer as main resin components. There is. According to this method, the fixability tends to be improved, but the weight average molecular weight / number average molecular weight (Mw / Mn) of the low molecular weight polymer is as small as 3.5 or less, and the insoluble infusible high molecular weight polymer Content 40-90
With a large amount of wt%, it is difficult to satisfy the offset resistance with high performance. In practice, the fixing property (especially high-speed fixing) and offset resistance are required unless the fixing device has a liquid supply device for preventing offset. It is extremely difficult to produce a toner that fully satisfies the properties.

Further, in JP-A-60-166958, the number average molecular weight (Mn)
A toner composed of a resin composition obtained by polymerization in the presence of low molecular weight poly α-methylstyrene having a molecular weight of 500 to 1,500 has been proposed.

Particularly, in the publication, the number average molecular weight (Mn) is 9,000 to 30,00.
Although the range of 0 is preferable, the fixing property becomes a practical problem when Mn is increased in order to further improve the offset resistance, and therefore it is difficult to satisfy the offset resistance with high performance.

Further, in JP-A-56-16144, a binder resin component having at least one local maximum value is contained in each region of the molecular weight of 10 ³ to 8 × 10 ⁴ and the molecular weight of 10 ⁵ to 2 × 10 ^{6 in} the molecular weight distribution by GPC. Toners have been proposed. In this case, the offset resistance, the fixing property, the filming and fusion to the photoconductor, the image property, etc. are excellent, but further improvement in the offset resistance and the fixing property of the toner is demanded. In particular, it is difficult for the resin to further improve the fixing property to maintain various other performances or to improve the fixing property to meet today's severe requirements.

In terms of development reproducibility as described above, particularly when a digital copying machine is used, when a conventionally used developer is diverted due to the peculiarity of the line latent image, toner is not used in the development process. Deterioration of the image quality due to the scattering of particles and thinning of the line image under high humidity conditions are often problems. In addition, the reversal development method that is usually used in OPC digital copiers has a very small latent image charge in the image area compared to the non-image area, and if toner with unstable charge is present on the photoconductor. The so-called reversal fog occurs, in which the toner is developed on the non-image portion having a large charge.

This is one of the major causes of the deterioration of the development reproducibility.
As one of the problems, it is considered that the additives constituting the toner are poorly dispersed. Especially, in the case of a one-component magnetic toner containing a magnetic substance, it is considered that the dispersibility of the added magnetic substance affects the developing characteristics of the toner. Has been.

Heretofore, as a technique relating to the improvement of the magnetic material used for toner, JP-A-58-9153 discloses that the surface of the magnetic material is treated with a titanium coupling agent, a silane coupling agent, or the like.
A method for improving the dispersibility of the magnetic substance in the toner has been proposed. In this case, although the dispersion of the magnetic material in the toner is improved, there arises a problem that the surface resistance of the magnetic material becomes too high, and the environmental stability of the toner tends to decrease. Further, JP-A-59-27901 discloses that a cubic magnetic material has a bulk density / coercive force ratio in the range of 0.0054 to 0.0129 g / ml-elstead, and thus development efficiency and image density are improved. Although it is said that the negative chargeability of the toner is improved, the dispersibility is not so taken into consideration. Therefore, it cannot be said to be sufficient in long-term durability, and it cannot be said to be effective for a negative charge latent image such as the OPC photoconductor widely used today.

Further, JP-A-56-91242 proposes to improve image density and image quality by using a magnetic substance having a bulk density of 0.45 g / ml or more and an aliphatic carboxylic acid or a metal salt thereof. However, it is considered that the aliphatic carboxylic acid or its metal salt selectively adheres to the surface of the magnetic material to increase the resistance of the magnetic material. Therefore, it is insufficient in environmental stability and especially in a high-speed machine.

As described above, there is a demand for a toner that can satisfy both the fixing performance and the development reproducibility, and particularly a toner that can favorably develop a digital latent image.

[Object of the Invention]

The present invention has been made to solve the above-mentioned problems, and an object thereof is to provide a toner having excellent fixing property and offset property, good image reproducibility, and no reversal fog. .

A further object of the present invention is to provide a toner that does not cause image deterioration even when used for a long period of time.

A further object of the present invention is to provide a toner which can be fixed at a low temperature and has excellent blocking resistance, and which can be sufficiently used even in a high temperature atmosphere in a small copying machine.

Further, it is an object of the present invention to provide a toner having excellent offset resistance, and further to provide a toner having high production efficiency.

In order to achieve the above-mentioned objects at the same time, various materials have been earnestly studied from various angles. As a result, they have found that the proportion of THF-insoluble matter in the binder resin and the molecular weight distribution of THF-soluble matter have a specific constitution and can be achieved by combining a magnetic material having a specified bulk density and shape.

That is, the present invention is based on the binder resin THF for toner.
Contains 10 to 70% by weight of insoluble matter, and the molecular weight distribution of THF soluble matter of binder resin by GPC is weight average molecular weight /
Number average molecular weight (Mw / Mn) ≧ 5, having a peak in the range of 2000 to 8000 and having a peak or shoulder in the range of 20000 to 70000, and having a molecular weight of 10000 or less in the binder resin 10 to 50 The present invention relates to a toner for electrostatic charge development, which comprises a resin composition contained by weight% and a spherical magnetic material having a bulk density of 0.6 g / ml or more.

Furthermore, the present invention relates to a toner for developing an electrostatic charge image, which contains an azo-based negatively chargeable control agent.

Furthermore, the present invention relates to an electrostatic charge image developing toner for reversal development of a digital latent image.

Specifically, the present invention is a toner for developing an electrostatic charge image having at least a binder resin and a magnetic substance, wherein the binder resin contains 10 to 70% by weight of the THF insoluble matter, and the THF soluble matter of the binder resin is contained. The molecular weight distribution by GPC is weight average molecular weight / number average molecular weight (Mw / Mn) ≧ 5, has a peak in the region of molecular weight 2,000 to 8,000, and has a peak or shoulder in the region of molecular weight 20,000 to 70,000, Contains 10 to 50 wt% of a component with a molecular weight of 10,000 or less relative to the binder resin, and has a bulk density of 0.6 g / m as a magnetic material.
The present invention relates to a toner for developing an electrostatic charge image, which contains a spherical magnetic substance having a size of 1 or more.

[Detailed Description of the Invention]

In order to achieve the above-mentioned objects at the same time, various materials have been studied, and their constitution and performance have been earnestly studied from various angles. As a result, in the binder resin, the THF insoluble matter basically affects the offset resistance and the sticking property, and the THF soluble matter having a molecular weight of 10,000 or less mainly causes the blocking property and the fusion to the photoreceptor. It has been found that the effect on the fixing properties and filming properties, and that the THF-soluble component with a molecular weight of 10,000 or more mainly affects the fixing property.
The ratio of the component having a molecular weight of 10,000 or less is preferably 10 to 50 wt%, preferably 20 to 39 wt%. In order to obtain sufficient performance, it is necessary to have a peak in the molecular weight range of 2,000 to 8,000 and a peak or shoulder in the molecular weight range of 20,000 to 70,000. No peak at 2,000-8,000, molecular weight 2,000
Although there is a peak at 0 or less, if the proportion of the component having a molecular weight of 10,000 or less is 50 wt% or more, blocking resistance, fusion to the photoreceptor, filming and the like become somewhat problematic. Molecular weight 8,
There is no peak at 000 or less and there is a peak at 8,000 or more, but if the proportion of the component having a molecular weight of 10,000 or less is 10 wt% or less, formation of coarse particles also poses a problem.

If there is no peak or shoulder in the region where the molecular weight is 20,000 or more and there is a peak only in the region where the molecular weight is 20,000 or less, the offset resistance becomes a problem. If there is no peak or shoulder in the molecular weight range of 20,000 to 70,000 and there is a main peak peak at 70,000 or more, pulverizability becomes a problem.

Further, the THF-soluble content needs to be Mw / Mn ≧ 5, and when Mw / Mn is 5 or less, the offset resistance tends to be lowered, which becomes a problem.

Preferably Mw / Mn is 80 or less, more preferably 1
0 ≦ Mw / Mn ≦ 60 is preferable.

Particularly, when Mw / Mn is 10 ≦ Mw / Mn ≦ 60, excellent performance is exhibited in various properties such as crushability, fixing property, offset resistance, and imageability.

Here, Mw is a weight average molecular weight measured by GPC described below, and Mn is a number average molecular weight measured by the same method.

And the THF insoluble content of the binder resin is 10 ~ 70w
t% is required. If the THF insoluble content is 10 wt% or less, the offset resistance becomes a problem, and if it exceeds 70 wt%, deterioration such as molecular chain breakage due to thermal kneading during toner production occurs. Preferably, the THF insoluble content is 15 to 49 wt% in terms of offset resistance.

The THF-insoluble matter in the present invention refers to the weight ratio of the polymer component (substantially crosslinked polymer) that becomes insoluble in the THF solvent in the resin composition in the toner, and the resin composition containing the crosslinking component. It can be used as a parameter indicating the degree of crosslinking. The THF-insoluble matter is defined as a value measured as follows.

That is, 0.5 to 1.0 g of a toner sample is weighed (W ₁ g), put in a cylindrical filter paper (for example, No.86R manufactured by Toyo Roshi Kaisha, Ltd.), put on a Soxhlet extractor, and 100 to 200 ml of THF is used as a solvent.
After time-extracting, the soluble component extracted with the solvent was evaporated, and then vacuum-dried at 100 ° C for several hours, and the THF-insoluble resin component amount was weighed (W ₂ g). The weight of the components other than the resin component such as the magnetic substance or pigment in the toner is (W ₃ g). THF
The insoluble content is calculated from the following formula.

In the present invention, the molecular weight of the chromatographic peak or / and the shoulder of GPC (gel permeation chromatography) is measured under the following conditions.

That is, the column was stabilized in a heat chamber at 40 ° C, THF (tetrahydrofuran) as a solvent was flown through the column at a flow rate of 1 ml per minute at this temperature, and the THF concentration of the resin was adjusted to 0.05 to 0.6% by weight as a sample concentration. Sample solution
Inject 50 to 200 μl and measure. In measuring the molecular weight of the sample, the molecular weight distribution of the sample was calculated from the relationship between the logarithmic value and the count number of a calibration curve prepared using several kinds of monodisperse polystyrene standard samples. As a standard polystyrene sample for creating a calibration curve, for example, Pressure Chemical C
o. or the molecular weight of Toyo Soda Kogyo Co., Ltd. is 6 × 10 ² , 2.1
× 10 ³ , 4 × 10 ³ , 1.75 × 10 ⁴ , 5.1 × 10 ⁴ , 1.1 × 10 ⁵ , 3.9 × 10 ⁵ ,
Use 8.6 × 10 ⁵ , 2 × 10 ⁶ , 4.48 × 10 ⁶ and at least 1
It is appropriate to use a standard polystyrene sample of about 0 points. An RI (refractive index) detector is used as the detector.

As the column, a plurality of commercially available polystyrene gel columns are preferably combined in order to accurately measure the molecular weight region of 10 ³ to 4 × 10 ⁶ , for example, μ-styr manufactured by Waters.
agel 500,10 ³ , 10 ⁴ , 10 ⁵ combination, Showa Denko Shodex KF-80M, KF-802,803,804,805 combination, or Toyo Soda TSKgel G1000H, G2000H, G2500H, G300
A combination of 0H, G4000H, G5000H, G6000H, G7000H, GMH is preferable.

The weight% of the binder resin having a molecular weight of 10,000 or less of the present invention cuts out the molecular weight of 10,000 or less of the chromatogram by GPC, and calculates the weight ratio with the cutout having a molecular weight of 10,000 or more. The weight% with respect to the binder resin is calculated.

On the other hand, for the magnetic material, it is necessary to select a material that has good dispersion with respect to the binder resin containing the gel component.
The value of the bulk density is preferably 0.6 g / ml or more, preferably 0.7 g / ml or more, preferably 0.8 g / ml or more, and more preferably 0.9 g / ml to 1.5 g / ml. When the bulk density is less than 0.6 g / ml, the magnetic substance is not sufficiently dispersed in the toner, the magnetic substance is unevenly distributed, and sufficient development reproducibility cannot be obtained.
In particular, the cubic magnetic substance has a bulk density up treatment effect, but has a problem as compared with the spherical magnetic substance. These series of phenomena are considered as follows.

The so-called corners in the cubic magnetic substance are very easily broken by stress, and are broken during the treatment for increasing the bulk density to produce fine magnetic powder. When such a magnetic material is used as a toner, the fine magnetic powder is not uniformly dispersed in the toner, so that it is difficult to obtain a toner having excellent developability.

In addition, since the cubic magnetic material has a particularly large remanence (hereinafter referred to as σ _r ) among the magnetic properties, the magnetic cohesive force of the toner using the magnetic material is large, and therefore the toner is independent for each particle. May not behave as a result, and this may reduce the image quality. This is particularly noticeable in the case of a digital latent image by a laser or the like, which is a serious problem.

Here, as a process of increasing the bulk density, a technique such as a fret mill can be used.

In addition, in this specification, the bulk density (g / cc) is JIS
(Japanese Industrial Standard) The value measured by K≡5101.

The resin composition having a high fixing performance as described above has a structure in which low-molecular components are microscopically present between the networks of the cross-linking components, so that the bulk density is small and air is present between the magnetic particles. In the case of a magnetic substance containing a large amount, the wettability is poor, and it is difficult to sufficiently wet the low molecular component and the magnetic substance. Also. Originally, the bulk density is 0.
A cubic magnetic substance as small as 3 g / ml is still insufficient, even if the bulk density is increased by using a fret mill or the like, it reaches only about 0.5 g / ml. However, since the spherical magnetic material has a bulk density of about 0.45 g / ml, it can be easily increased to 0.6 g / ml or more by a treatment for increasing the bulk density. High durability can be realized.

In particular, in reversal development of a digital latent image using an OPC photoreceptor, a toner having high durability satisfying reversal fog is first obtained at a bulk density of 0.6 g / ml or more. This is probably because the dispersibility is clearly improved. Further, the direction in which the bulk density is higher is the direction in which the dispersion is better.

The residual magnetism (σ _r ) of the spherical magnetic substance is 5 emu / g or less,
The coercive force (Hc) is generally as small as 600e or less.

Further, it was further found that the dispersibility is further improved and the image quality is also improved particularly when a monoazo negative-charge controlling agent is used in combination. The reason for this is not clear, but the decomposition product of the polymerization initiator or the group attached to the end of the polymer and the monazo compound have some kind of interaction, and the magnetic substance with the charge control agent attached to the surface is well dispersed. It is presumed that it will be done.

The resin composition in the toner of the present invention is styrene,
Those obtained by polymerizing one or more kinds of monomers selected from acrylic acids, methacrylic acids and their derivatives are preferable from the viewpoint of developing characteristics and charging characteristics. Examples of monomers that can be used include styrenes such as styrene, α-methylstyrene, vinyltoluene, and chlorostyrene. Acrylic acids, methacrylic acids and their derivatives include acrylic acid, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, n-tetradecyl acrylate, n-acrylic acid. Hexadecyl, lauryl acrylate, cyclohexyl acrylate,
Acrylic acid esters such as diethylaminoethyl acrylate and dimethylaminoethyl acrylate are listed,
Similarly, methacrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, amyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate,
Methacryl such as decyl methacrylate, dodecyl methacrylate, lauryl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, dimethylaminoethyl methacrylate, glycidyl methacrylate, stearyl methacrylate. Examples thereof include acid esters. In addition to the above-mentioned monomers, a small amount of other monomers within a range that can achieve the object of the present invention, such as acrylonitrile, 2-vinylpyridine, 4-vinylpyridine, vinylcarbazole, vinylmethyl ether, butadiene, isoprene, maleic anhydride, Maleic acid, maleic acid monoesters, maleic acid diesters, vinyl acetate and the like may be used.

Examples of the cross-linking agent used in the toner of the present invention include divinylbenzene, bis (4-acryloxypolyethoxyphenyl) propane, ethylene glycol diacrylate, 1,3-butylene glycol diacrylate, and 1-functional cross-linking agents. , 4-butanediol diacrylate, 1,5
-Pentanediol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, diethylene glycol diacrylate, triethylene glycol acrylate, tetraethylene glycol diacrylate, polyethylene glycol # 200,
Examples include # 400 and # 600 diacrylates, dipropylene glycol diacrylate, polypropylene glycol diacrylate, polyester type diacrylate (MANDA Nippon Kayaku), and those obtained by replacing the above acrylates with methacrylates.

Pentaerythritol triacrylate, trimethylolethane triacrylate, trimethylol propane triacrylate, tetramethylol methane tetraacrylate, oligoester acrylate and its methacrylate, 2,2-bis (4-methacryloxy, polyethoxyphenyl) ) Propane, diallyl phthalate, trial cyanurate, triallyl socyanurate, triallyl isocyanurate, triallyl trimellitate, and diaryl chlorendate.

As a method of synthesizing the binder resin according to the present invention, a method of synthesizing basically two or more kinds of polymers is preferable.

That is, it is a method of obtaining a resin composition by dissolving a first polymer that is soluble in THF and soluble in a polymerization monomer in the polymerization monomer, and polymerizing the monomer. In this case, a composition is formed in which the former and latter polymers are uniformly mixed.

The first polymer soluble in THF is preferably solution-polymerized or ionic polymerized, and the second polymer for producing a component insoluble in THF is dissolved under the condition that the first polymer is dissolved. It is preferable to synthesize by suspension polymerization or bulk polymerization in the presence of a crosslinkable monomer. The first polymer is 10 parts by weight per 100 parts by weight of the polymerizable monomer for forming the second polymer.
It is preferable to use ˜120 (preferably 20 to 100 parts by weight) parts by weight.

Examples of the magnetic substance contained in the magnetic toner of the present invention include iron oxide such as magnetite, hematite, and ferrite, or a compound of a divalent metal and iron oxide; a metal such as iron, cobalt, nickel, or aluminum of these metals; Cobalt, copper, lead, magnesium, tin, zinc, antimony,
Examples thereof include alloys of metals such as beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten and vanadium, and mixtures thereof.

The following substances control the chargeability of the toner.

Nitrohumic acid and its salts or dyes and pigments such as CI14645 described in JP-A-50-133338, JP-B-55-4
Metals such as salicylic acid, naphthoic acid and dicarboxylic acids such as Zn, Al, Co, Cr and Fe described in No. 2752, Japanese Patent Publication No. 58-41508, Japanese Patent Publication No. 58-7384, Japanese Patent Publication No. 59-7384. Complex,
Sulfonated copper phthalocyanine pigments, nitri groups, halogen-introduced styrene oligomers, chlorinated paraffins, etc. Particularly, from the viewpoint of dispersibility, metal complex salts of monoazo dyes, metal complexes of salicylic acid, alkylsalicylic acid, naphthoic acid, and dicarboxylic acid are preferable.

The following compounds are exemplified as particularly preferable monoazo substances.

[In the above formula, M represents Cr, Fe, Co or Al. With the toner of the present invention, good results are obtained even when an additive is mixed if necessary. As the additive, for example, a lubricant such as Teflon, zinc stearate, polyvinylidene fluoride, or the like, and polyvinylidene fluoride is preferable. Alternatively, abrasives such as cerium oxide, silicon carbide, and strontium titanate, among which strontium titanate is preferable.
Alternatively, for example, fluidity-imparting agents such as colloidal silica and aluminum oxide, among which hydrophobic colloidal silica is particularly preferable. There are anti-caking agents, conductivity-imparting agents such as carbon black, zinc oxide, antimony oxide, tin oxide, etc., fixing aids such as low molecular weight polyethylene, low molecular weight polypropylene, various waxes, etc. or anti-offset agents. Also, a small amount of reverse polarity white fine particles and black fine particles can be used as a developing property improver.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited thereto. The parts in the following formulations are parts by weight.

Synthesis Example 1 200 parts by weight of cumene was placed in a reactor and heated to the reflux temperature. Add 100 parts by weight of styrene monomer and di-tert.
A mixture of 8.5 parts by weight of -butyl peroxide was added dropwise under a cumene reflux for 4 hours. Under cumene reflux (14
Solution polymerization was completed at 6 ° C to 156 ° C) to remove cumene.
The polystyrene obtained is soluble in THF, Mw = 3,500,
Mw / Mn = 2.52, the molecular weight of the main peak of GPC is 3,
It was 300 and Tg = 56 ° C.

30 parts by weight of the above polystyrene was dissolved in the following monomer mixture to obtain a mixed solution.

Partially saponified polyvinyl alcohol in the above mixed solution.
170 parts by weight of water in which 1 part by weight was dissolved was added to obtain a suspension dispersion liquid. The above suspension dispersion was added to a reactor in which 15 parts by weight of water was charged and the atmosphere was replaced with nitrogen, and a suspension polymerization reaction was carried out at a reaction temperature of 70 to 95 ° C. for 6 hours. After the reaction was completed, it was filtered off, dehydrated and dried to obtain a composition of polystyrene and a styrene-n-butyl acrylate copolymer. In the composition, the THF insoluble matter and the THF soluble matter were uniformly mixed, and the polystyrene and the styrene-n-butyl acrylate copolymer were uniformly mixed. The THF insoluble content (measured with a powder of 24 mesh paths and 60 mesh particles) of the obtained resin composition was 36 wt%. Also, when the molecular weight distribution of the THF-soluble component was measured, the GPC chart had peaks at positions of about 377,000 and about 33,000, and Mn = 0.5.
30,000, Mw = 126,000, Mw / Mn = 23.8, molecular weight less than 10,000 is 25wt
%Met. Furthermore, the Tg of the resin is 58 ° C, and the glass transition point Tg ₁ of less than 10,000 components separated by GPC is 56 ° C.
Met.

The properties of each resin and resin composition relating to the molecular weight were measured by the following methods.

Using Shodex KF-80M as a column for GPC measurement, the GPC measuring device (150C ALC / GPC manufactured by Waters Co., Ltd.) was installed in the heat chamber at 40 ° C., and the THF flow rate was 1 ml / min. Soluble concentration of about 0.1% by weight) 200μ
GPC was measured by injecting 1 l. As a calibration curve for molecular weight measurement, the molecular weight is 0.5 × 10 ³ , 2.35 × 10 ³ , 10.2 × 10 ³ , 35 ×
10 ³ , 110 x 10 ³ , 200 x 10 ³ , 470 x 10 ³ , 1200 x 10 ³ , 2700
A THF solution of 10 points of a monodisperse polystyrene reference substance (manufactured by Waters Co.) of × 10 ³ and 8420 × 10 ³ was used.

Synthesis Example 2 150 parts by weight of cumene was placed in a reactor and heated to the reflux temperature. The following mixture was added dropwise under cumene reflux for 4 hours.

Polymerization was completed under cumene reflux (146-156 ° C),
The cumene was removed. Obtained styrene-acrylic acid n-
Butyl copolymer has Mw = 6,800, Mw / Mn = 2.24, molecular weight 7,
It had a main peak at position 000 and had Tg of 63 ° C.

40 parts by weight of the styrene-n-butyl acrylate copolymer was dissolved in the following monomer mixture to obtain a mixture.

Partially saponified polyvinyl alcohol in the above mixture 0.1
170 parts by weight of water in which 1 part by weight was dissolved was added to obtain a suspension dispersion liquid.

The above dispersion liquid was added to a reactor in which 15 parts by weight of water was charged and the atmosphere was replaced with nitrogen, and the reaction was carried out at a reaction temperature of 70 to 95 ° C. for 6 hours. After completion of the reaction, it is filtered, dehydrated and dried to give styrene-acrylic acid n-
A composition of a butyl copolymer and a styrene-n-butyl methacrylic acid copolymer was obtained.

Comparative Synthesis Example 1 30 parts by weight of the polystyrene obtained in Synthesis Example 1 was dissolved in the following monomer mixture to give a mixed solution.

The above mixture was subjected to suspension polymerization in the same manner as in Synthesis Example 1,
A composition of polystyrene and a styrene-n-butyl acrylate copolymer was obtained. In GPC of the THF-soluble component of this composition, there were peaks at the molecular weights of about 4000 and 150,000.

Example 1 After the above materials were mixed, they were kneaded for 20 minutes with a two-roll mill heated to 150 ° C. The kneaded product was cooled, coarsely pulverized, pulverized using a fine pulverizer using a jet air flow, and further classified using an air classifier to obtain a black fine powder having a volume average particle diameter of 12.0 μm. Further, 0.6 part by weight of the colloidal silica fine powder was dry-mixed with 100 parts by weight of the black fine powder obtained here to obtain a toner (developer).

Next, an image production test was conducted using the toner obtained here. The test was equipped with an OPC photoconductor and a thermal roll fuser, 3
A laser beam printer that forms a latent image with a 00 dpi laser beam and performs reversal development was used. During the test, the temperature of the hot roll fixing device was set to 170 ° C. Further, the image used for the image development test was a so-called 1-dot 2-space image in which the ratio of the latent image band to the blank band was 1: 2.

As a result of the image output test, a good image without scattering and reversal fog was continuously produced until the toner was used up, and a problem such as filming did not occur.

Further, the cleaning mechanism of the fixing device was removed and the above-mentioned image forming test was conducted, but there was no problem in fixing property and offset did not occur.

Example 2 After mixing the above materials, a toner was obtained in the same manner as in Example 1.

Next, an image production test was conducted using the toner obtained here. The image formation test was performed in the same manner as in Example 1 except that a laser beam of 400 dpi was used and the temperature of the heat roll fixing device was set to 160 ° C.

As a result of the image output test, a good image without scattering and reversal fog was obtained until the toner was used up, and there was no problem in fixing property and offset property at all.

Comparative Example 1 After mixing the above materials, a toner was obtained in the same manner as in Example 1.

Next, an image forming test was conducted in the same manner as in Example 1 using the toner obtained here.

As a result of the image output test, some scattering occurred and the durability was 500.
The image at the time of printing was not at a practical level, but was clearly inferior to that of Example 1.

Further, the image density tended to be lowered as it was durable, and the dispersibility was inferior to Example 1 and not good, as inferred from the gloss of the kneaded product.

Comparative Example 2 After mixing the above materials, a toner was obtained in the same manner as in Example 1.

Next, an image formation test was conducted in the same manner as in Example 2 using the toner obtained here.

As a result of the image output test, an image without scattering was obtained until the toner was used up, but the image density was rather low and it could not be said to be good. The fixability was very poor and was a serious problem in practical use.

Example 3 A toner was prepared using the resin composition of Synthesis Example 1.

After the above materials were mixed, they were heat kneaded using an extruder set at 150 ° C. The kneaded product had a glossy surface and had a feel that the magnetic substance was well dispersed.

This was coarsely pulverized, finely pulverized, and further classified by air force to obtain toner powder having a volume average diameter of 9.5 μm.

To this, colloidal silica was added in the same manner as in Example 1 to obtain a toner (developer). This is a Canon high-speed copying machine NP
Tested with -8570 (70 sheets / min, 100V).

An image output durability test of about 100,000 sheets was conducted, and the image density was 1.45 from the beginning, and it was stable. In addition, the image had good fine line reproducibility and excellent dot reproducibility.

Regarding fixing, the cleaning device of the fixing machine was removed and tested, but the offset phenomenon was not observed, winding was good, and the set temperature of the fixing roller was lowered by 10 ° C., but fixing was sufficient.

In addition, there was no fusion of the photoconductor, and no fusion in the crushing device during toner production.

Example 4 A toner was prepared in the same manner as in Example 1 except that the spherical magnetic substance having a bulk density of 1.0 g / ml was used.

The obtained toner has a volume average diameter of 11.5 μm, which is almost the same. Colloidal silica was added to this as in Example 1 to obtain a developer. This was evaluated in the same manner as in Example 1.

As a result, the fixing-related performance was the same, but the image forming test showed a tendency better than that of Example 1. That is,
Regarding the reversal fog, when the machine was remodeled to make the non-image portion apparently have a more severe potential, it was found that the reversal fog of 60V had more room than in Example 1.

Example 5 A toner was prepared in the same manner as in Example 1 except that the spherical magnetic material having a bulk density of 0.6 was used. In the image output test, a good image without scatter and fog was obtained, but the overall evaluation was inferior to that of Example 1.

Example 6 In Example 1 as well, a toner was prepared in the same manner as in Example 1 except that a chromium dialkylsalicylate complex was used instead of the monoazo negative charge control agent. When a digital image output test was performed in the same manner as in Example 1, a slight deterioration in image quality was observed as compared with the image obtained in Example 1.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location G03G 9/08 346 (56) References JP-A 61-155223 (JP, A) JP-A 59 -107359 (JP, A) JP 61-163347 (JP, A) JP 59-29254 (JP, A) JP 62-294260 (JP, A)

Claims (3)

[Claims] 1. A toner for developing an electrostatic image comprising at least a binder resin and a magnetic material, comprising:
The THF insoluble content is 10 to 70% by weight, and the molecular weight distribution of the THF soluble content of the binder resin by GPC is weight average molecular weight / number average molecular weight (Mw / Mn) ≧ 5, and the molecular weight is 2,000.
It has a peak in the region of ~ 8,000 and has a molecular weight of 20,000-70,
A spherical magnetic material having a peak or shoulder in the area of 000, containing 10 to 50% by weight of a component having a molecular weight of 10,000 or less with respect to the binder resin, and having a bulk density of 0.6 g / ml or more as a magnetic material. A toner for developing an electrostatic charge image, which comprises: 2. A charge control agent comprising a monoazo negative charge control agent.
6. The toner for developing an electrostatic charge image according to the item. 3. The toner for developing an electrostatic charge image according to claim 1 or 2, which is a toner for reversal development of a digital latent image.