JP3445524B2 - Electrostatic charge developing toner and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic charge developing toner used in an electrophotographic copying machine and a method for manufacturing the same.

[0002]

2. Description of the Related Art Generally, in electrophotography, an electric latent image is formed on a photosensitive drum, the latent image is then developed with toner, and the toner image is transferred to a transfer material such as paper as required. After that, it is fixed by means of heating, pressurizing or the like to obtain a copy. Developers used in such an electrophotographic method include a two-component developer including a toner and a carrier, and a one-component developer having the functions of the toner and the carrier at the same time. The one-component developer is further classified into a magnetic one-component developer and a non-magnetic one-component developer. The two-component developer has excellent electrophotographic characteristics such as transferability, fixability, and environmental resistance, but requires a toner concentration sensor to control the mixing ratio of toner and carrier, and the life of the developer is short. However, there is a problem that the stirring mechanism of the developer becomes complicated. On the other hand, the magnetic one-component developer does not require the toner concentration sensor described above, and the developing device can be easily miniaturized. However, since it contains magnetic particles, it has a problem of poor fixability. From such a background, in order to make the apparatus compact and simple and to establish the fixing property, a method of using a non-magnetic toner as a one-component developer has been proposed and put into practical use in recent years.

The one-component developing method using non-magnetic toner includes a contact-type non-magnetic one-component developing method in which a developing roller carrying a developer is brought into contact with a photosensitive drum having an electrostatic latent image for development. There is a non-contact type non-magnetic one-component developing method in which a non-magnetic toner on the developing roller is caused to fly by developing by providing a certain space gap between the roller and the photosensitive drum. In both the contact type and non-contact type developing methods, a thin layer of the developer must be uniformly formed on the developing roller, and therefore the gap between the developer and the layer regulating member is designed to be very narrow.

As a result, in the conventional non-magnetic one-component developing method, a large mechanical load is applied to the developer, and the developer is fused to the layer regulating member by frictional heat generated by its contact and sliding. Was being generated. When the developer is fused to the layer regulating member, the triboelectric chargeability of the developer is impaired,
The developer becomes difficult to be charged, and as a result, there is a problem of so-called fogging in which the developer adheres to the non-image area and so-called scattering of the developer blown out from the developing machine.

Further, in recent years, from the viewpoint of energy saving, it has been required to set the heat energy at the time of melting and fixing the toner low, and it is necessary to select a resin capable of fixing at a lower temperature.

Conventionally, a toner containing a resin which melts at a lower temperature required for such low energy fixing is generally inferior in mechanical strength, and therefore, the nonmagnetic single component as described above is used. When applied to the developing method, the phenomenon of fusion bonding to the layer regulating member becomes remarkable. Therefore, it is an indispensable subject to prevent the fusion by maintaining the mechanical strength and to achieve the contradictory property of improving the low temperature fixing property. Further, the above-mentioned problems are not limited to the non-magnetic one-component developing method, but also the two-component developer applied to high-speed copying.

That is, the speeding up of copying strengthens the contact and impact between the toner and the carrier in the process of development, and as a result, the toner easily adheres to the surface of the carrier. or,
As the speed increases, more heat energy is required for fixing, and low-energy fixing is an essential issue. Therefore, in any of the developing methods, it is essential to improve the mechanical strength of the toner and the low temperature fixability at the same time.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above situation in the prior art, in which an electrostatic charge developing toner used in a non- magnetic one-component developing system is brought into contact with a layer regulating member. A toner for electrostatic charge development, which does not fuse to the layer regulating member, can obtain good developability without fogging or scattering, has good blade cleaning properties, and can be fixed at a lower temperature, and It is intended to provide a manufacturing method.

[0009]

As a result of intensive studies made by the present inventors to solve the above problems, the toner for electrostatic charge development which can be preferably used mainly in the non-magnetic-component developing method, and the production thereof. Created the way.

[0010] That is, the invention of claim 1, serving as the polymerizable monomer _CH 2 = CHCOO and _{(CH 2)} n CH ₃ (where n is an integer of 10 to 18), the other polymerizable monomer, a coloring A toner for electrostatic charge development, comprising a dispersed phase containing an agent and a polymer A, and a continuous phase composed of an aqueous medium, mixed at a controlled ratio, dried after polymerization , and having a glass transition point of the polymer A. A toner for electrostatic charge development, which has a Tg of 55 to 80 ° C., a flow softening temperature Tm of 95 to 155 ° C. by a Koka type flow tester, and a number average molecular weight Mn of 3000 to 8000 by GPC. The invention according to claim 2 is the toner for electrostatic charge development according to claim 1, wherein the polymer A is at least one of an epoxy resin and a polyester resin, and the invention according to claim 3 is the polymer A. Is a crosslinking component The toner for electrostatic charge development according to claim 1 or 2, characterized in that the residual amount of the polymerization initiator is 1000 ppm or less. The electrostatic charge developing toner according to claim 5, wherein the radius of the minimum circumscribed circle of the toner particles is Rl and the radius of the maximum inscribed circle of the toner particles is Rs, Ps = Rl / Rs The maximum frequency exists in the range where the degree of deformation Ps is 1.1 or more and 1.4 or less, 10% by number or more of toner particles having Ps of 1.5 or more are contained, and Ps is 2.0 or more. When the toner particles are contained in an amount of 3% by number or more, and the projected area of the toner particles is S and the peripheral length of the toner particles is 1, the projected area of the toner particles represented by Sf = (4πS) / l ² (shape coefficient ) Sf is 0.6
The electrostatic charge developing toner according to claim 1, wherein 5 ≦ Sf ≦ 1.0.

Further, regarding the method for producing the above toner,
The invention of claim 6 provides CH ₂ ═CHC as the polymerizable monomer.
_{OO (CH 2) n CH 3} ( where n is an integer of 10 to 18)
And, using other polymerizable monomers, the dispersed phase containing the colorant and the polymer A, and the continuous phase consisting of the aqueous medium are held in independent tanks, respectively, and through independent paths, Both are continuously supplied to the granulator at a controlled ratio to prepare a suspension having polymerizable droplet groups of a desired size, and then the suspension is introduced into a polymerization tank to carry out a polymerization reaction. A method for producing a toner for electrostatic charge development, which is obtainable by drying the polymer A, wherein the glass transition point Tg of the polymer A is 5
5 to 80 ° C., a flow softening temperature Tm by a Koka type flow tester is 95 to 155 ° C., and a number average molecular weight Mn by GPC is 3000 to 8000. And claim 7
7. The toner for electrostatic charge development according to claim 6, wherein the heat treatment of the toner is carried out in a temperature range not lower than the glass transition point Tg of the polymer A and not higher than Tg + 10 ° C. after the drying step. It is a manufacturing method, and the invention of claim 8 is
Polymer A is free of crosslinking components.
The method for producing a toner for electrostatic charge development according to 6 or 7 .

[0012]

1 is a schematic configuration diagram of a developing device used in a non-contact type non-magnetic one-component developing method to which the electrostatic charge developing toner of the present invention is applied. In FIG. 1, reference numeral 21 is a photosensitive drum, 22 is a hopper, 23 is an electrostatic charge developing toner, 24 is a layer regulating member, 25 is a developing roller using an elastic body carrying the electrostatic charge developing toner, and 26 is A toner leakage preventing member 27 for electrostatic charge developing is a stirrer. In this developing device, an electrostatic latent image is formed on the photosensitive drum 21 by a known electrophotographic method, and the electrostatic charge developing toner 23 is accommodated in the hopper 22. The charge developing toner 23 is carried on the developing roller by the layer regulating member 24 so as to have a constant layer thickness, and is charged by friction with the layer regulating member 24.

The developing roller 25 includes the photosensitive drums 21 and 1.
It is installed via a gap of 20 to 300 μm, or installed so as to be in direct contact. When developing in a non-contact manner, the developing roller 25 does not necessarily have to be an elastic body, and a metal roller made of aluminum or the like can be used.

A DC or AC voltage bias is applied to the developing roller 25. The electrostatic charge developing toner carried on the developing roller 25 is conveyed by the rotation of the developing roller 25, and due to the potential difference between the photosensitive drum 21 having an electrostatic latent image and the developing roller 25, the photosensitive drum 21.
Is developed on the surface of, and the electrostatic latent image is visualized in a non-contact manner.

Next, the electrostatic charge developing toner according to the present invention will be described in detail. The toner for electrostatic charge development of the present invention is prepared by adding a polymerization initiator to a dispersion liquid in which a colorant and a polymer A are dispersed in a polymerizable monomer, and then suspending the polymerizable monomer in an aqueous medium. Colored particles obtained by polymerization. Examples of the polymerizable monomer used in the present invention include the following compounds. Styrene, o-methylstyrene, m-methylstyrene, p
-Methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-ethylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-tert- Butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, and other styrenes and their derivatives; ethylene, propylene, butylene, isobutylene, and other ethylenically unsaturated monoesters. Olefins; Vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromide, vinyl fluoride; Organic acid vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate; Methacrylic acid, methyl methacrylate, methacrylic acid Ethyl, propyl methacrylate, n-butyl methacrylate, Methacrylic acid n- octyl, dodecyl methacrylate, 2-ethylhexyl methacrylate,
Methacrylic acid and its derivatives such as stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate; acrylic acid, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate. , N-octyl acrylate, dodecyl acrylate,
Acrylic acid and its derivatives such as 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether; vinyl methyl ketone, vinyl hexyl ketone , Vinyl isopropenyl ketone and other vinyl ketones; N-vinyl pyrrole, N-vinyl carbazole, N-vinyl indole, N-vinyl pyrrolidone and other N-vinyl compounds; vinyl naphthalene compounds; acrylonitrile, methacrylonitrile, acrylamide and the like. These monomers may be used alone or in combination of two or more. It is preferable to use styrene or a styrene derivative alone or in combination with other monomers in order to improve the environmental characteristics and durability of the non-magnetic toner.

Examples of the colorant include black colorants such as carbon black, acetylene black, lamp black, channel black and aniline black, and chromatic colors such as farnal blue, permanent blue, nigrosine blue and phthalocyanine. Examples thereof include cyan pigments, rose bengal, xanthene-based magenta dyes, quinacridone-based magenta color pigments, monoazo-based red pigments, and disazo-based yellow pigments, but are not limited thereto.

As the polymer A used in the present invention, an epoxy resin, a polyester resin, a polystyrene resin, a styrene-acrylic acid ester copolymer resin, a silicone resin or the like can be used, and among them, the mechanical strength of the toner is good. Therefore, it is preferable to use at least one kind of epoxy resin and polyester resin. The polymer A has a glass transition point Tg of 55 to 80 ° C. and a flow softening temperature Tm of 95 to 1 by a Koka type flow tester.
55 ° C., number average molecular weight Mn by GPC is 30
It is necessary to be 00 to 8000.

Further, the toner of the present invention in which the polymer A satisfying the above-mentioned conditions is mixed in the dispersed phase has very good mechanical strength, and there is no fusion to the layer regulating member, which is one of the problems.
It was found that good developability can be obtained. Although the cause of this is not always clear, it is considered that these polymers A are concentrated in the surface layer portion of the toner particles, and it is presumed that they are very effective in improving the mechanical strength.

According to the studies made by the present inventors, when the glass transition point Tg of the polymer A is less than 55 ° C., fusion is apt to occur.
It was found that if the temperature exceeds 0 ° C., good fixability cannot be obtained.
Similarly, it has been found that when the flow softening temperature Tm is less than 95 ° C., fusion tends to occur, and when it exceeds 155 ° C., the fixability is deteriorated. The Tg in the present invention means the temperature at the midpoint between the endothermic start temperature (shoulder value) and the peak value in the endothermic curve of DSC manufactured by Shimadzu Corporation. Similarly, the number average molecular weight Mn by GPC is 300.
It was found that when it is less than 0, fusion tends to occur, and when Mn exceeds 8000, the fixability is deteriorated. In addition,
In the present invention, the higher the acid value of the polymer A, the more
It was found that the polymer A is likely to be unevenly distributed in the surface layer portion of the toner particles, but when these values are high in the toner characteristics, the environmental characteristics are inferior. Therefore, it is desirable that the acid value of the polymer A is as low as possible. . According to the study by the present inventors, the acid value is 20 m.
It has been found that g / KOH mg or less is desirable.

Further, the polymer A in the present invention preferably contains no crosslinking component. This is because the cross-linking component is difficult to dissolve in the polymerizable monomer in the dispersed phase, so that the surface of the particles after granulation is not uniformly formed, which may adversely affect various properties of the toner. Because there is.

The term "crosslinking component" as used herein means one in which no gel component is observed when polymer A is dissolved in tetrahydrofuran (hereinafter referred to as "THF"). Specifically, 100 mg of Polymer A and 25 cc of THF were put in a centrifuge tube, stirred and left for 24 hours, and then 1 rpm at 15,000 rpm.
Centrifuge for 0 minutes, then discard 20 cc of supernatant,
20 cc of THF is added, and then 20 cc of THF is added after centrifugation under the same conditions, and 20 cc of supernatant is discarded after centrifugation under the same conditions. Then, after evaporating THF in a water bath at 80 ° C, dry it at 12 ° C in a dryer at 90 ° C.
The remaining amount after time drying is defined as the gel content. Further, the phrase "substantially free of gel content" means that the gel content is within 5% in this measurement.

In the present invention, the residue of the polymerization initiator is
It is preferably 1000 ppm or less. If the residue of the polymerization initiator exceeds 1000 ppm, not only an offensive odor may be generated from the toner but also a smoke generation phenomenon may be generated during fixing. The above smoke generation phenomenon is largely due to the residue of the polymerization initiator.

In the conventional kneading and pulverizing method, the residue of the polymerization initiator in the resin can be volatilized and removed at the time of melt kneading, and the above-mentioned smoke generation phenomenon does not pose a problem. In the polymerization toner, it is extremely difficult to introduce a step of volatilizing and removing the polymerization initiator. The amount of the polymerization initiator used is desirably as small as possible, and
In addition to optimizing the polymerization conditions to increase the polymerization rate, it is important to select a polymerization initiator with less residue.

Next, the electrostatic charge developing toner specified in claim 5 will be described with reference to FIG. First, when a particle image obtained by magnifying an electrostatic charge developing toner specified in claim 5 by an optical microscope 150 times is defined as a toner particle in the claim, 1) Ps = Rl / of the toner particle is defined. Deformation degree (Ps) represented by Rs and 2) Shape factor (S represented by Sf = (4πS) / l ²
It is preferable that f) satisfies the following conditions. However, as shown in FIG. 2, Rl is the radius of the minimum circumscribed circle of the toner particle 11,
s is the radius of the maximum inscribed circle of the toner particle 11, S is the projected area of the toner particle, and 1 is the perimeter of the toner particle 11. The sampling frequency for Ps measurement and Sf measurement is 200 or more. (1) Preferred conditions for the degree of different diameter (Ps) -The maximum frequency is in the range of 1.1 or more and 1.4 or less . -Containing 10% by number or more of 1.5 or more toner particles and 3% by number or more of 2.0 or more toner particles. (2) Preferable condition of shape factor (Sf) ・ The relation of 0.65 ≦ Sf ≦ 1.0 is satisfied.

The toner particles having a Ps in the range of 1.1 to 1.4 have a shape relatively close to a sphere, the stress that the toner particles receive in the developing device is low, and the blade cleaning property is Ps close to a true sphere. Better than toner particles of about 0 to 1.1.

However, when the toner has a high charge,
In some cases, the adhesion of toner particles to the photoconductor is increased, making blade cleaning difficult. Even in such a case, by containing 10 number% or more of toner particles having a relatively high degree of irregularity of Ps of 1.4 or more, the blade cleaning property and the toner fusion in the developing section are suppressed. You can Further, more desirably, by containing 3% by number or more of toner particles having Ps of 2.0 or more, it is possible to further improve the blade cleaning property, prevent toner fusion in the developing portion, and improve blade cleaning property. It is possible to achieve a higher level of compatibility.

The shape factor Sf value is 0.65.
It is desirable that the range is ≦ Sf ≦ 1.0. If the Sf value is less than 0.65, round-edging of particles is insufficient, and even if the irregularity degree Ps value is within a desired range, toner fusion to the layer regulating member may occur. .

By the way, as for the method of imparting a distribution to the shape itself as described above, in the case of the suspension polymerization method,
The heating temperature and heating time in the warming granulation step can be arbitrarily controlled, but the distribution state of the shape also depends on the particle size during suspension.

Next, the manufacturing method of the present invention will be described. First, a dispersion liquid containing a polymerizable monomer, a colorant, and a polymer A is prepared. At this time, it is preferable to add an organic peroxide to the dispersion liquid in order to uniformly disperse the colorant in the polymerizable monomer. Particularly preferred is an organic peroxide having an alkyl group having the longest carbon atom chain and having 13 or more carbon atoms. Examples of such organic peroxides include the following compounds. Stearyl peroxide, palmityl peroxide, behenyl peroxide, myristyl peroxide,
Stearyl peroxyphenoxyacetate, myristyl peroxyphenoxyacetate, α-cumylperoxystearate, α-cumylperoxymyristyrate, t-butylperoxystearate, t-butylperoxymyristylate, α-cumylper The amount of the above-mentioned organic peroxide such as oxybehenate, α-cumylperoxyacetylate, t-butylperoxybehenate, t-butylperoxyacetylate and the like is the polymerizable monomer 10
0.01 to 10 parts by weight relative to 0 parts by weight, preferably
It is 0.1 to 5 parts by weight.

As a method of dispersing the colorant in the polymerizable monomer, a method of heating the dispersion while stirring is used. In that case, you may use an ultrasonic disperser etc. together. The heating temperature is 40 to 140 ° C., and the heating time is 30 minutes to several hours. Then, a polymerization initiator is added to the dispersion, and the polymerizable monomer is suspension-polymerized in an aqueous medium to obtain a non-magnetic toner.

The polymerization initiator used in the present invention is preferably soluble in the polymerizable monomer. Examples of such a polymerization initiator include 2,2'-azobisisobutyronitrile, 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis-4-methoxy-2, 4-
Examples thereof include dimethyl valeronitrile, other azo or diazo polymerization initiators; benzoyl peroxide, methyl ethyl ketone peroxide, isopropyl peroxy carbonate, and other peroxide polymerization initiators.

In the present invention, it is preferable to use a combination of two or more of the above-mentioned polymerization initiators for the purpose of controlling the molecular weight and the molecular weight distribution or the reaction time. If necessary, a water-soluble polymerization initiator such as ammonium persulfate or potassium persulfate may be used together. The amount of the polymerization initiator used is usually 0.1 to 20 parts by weight, preferably 1 to 5 parts by weight, based on 100 parts by weight of the polymerizable monomer. If the amount of the polymerization initiator is less than 0.1 parts by weight, the molecular weight of the product polymer becomes so large that the properties as a non-magnetic toner are not satisfied, while if the amount of the polymerization initiator exceeds 20 parts by weight, the polymerization product is Is not preferable because the molecular weight of is too small. On the other hand, if the amount exceeds 20 parts by weight, as described above, the residue derived from the polymerization initiator increases, and an undesirable phenomenon such as smoking during fixing occurs.

The above suspension polymerization reaction is preferably carried out in the presence of a suspension stabilizer. Generally, in suspension polymerization, a surfactant having a hydrophilic group and a hydrophobic group in the molecule is often used as a suspension stabilizer. Suspension stabilizer has a hydrophilic group, a hydroxyl group, a carboxyl group and other, polar groups such as sulfonic acid and salts thereof, as a hydrophobic group, is composed of non-polar groups such as fatty acids and aromatics, It has the ability to prevent coalescence of the monomer composition particles formed by the granulation process and stabilize them. Examples of such suspension stabilizers include polyvinyl alcohol, casein, gelatin, methyl cellulose, methyl hydroxypropyl cellulose, cellulose derivatives such as ethyl cellulose, starch and derivatives thereof,
Examples thereof include poly (meth) acrylic acid and salts thereof. These suspension stabilizers function to coat the surface of the solvent during the polymerization reaction to prevent coalescence of droplets and agglomeration.

Further, in the production of the electrostatic charge developing toner of the present invention, in order to improve blocking resistance and durability,
Suspension polymerization may be carried out by adding a crosslinking agent such as divinylbenzene. Further, a charge control agent may be added if necessary. Examples of such a charge control agent include a nigrosine dye, a quaternary ammonium salt and the like if it has a positive charging property, and a metal of an organic compound having a carboxyl group, a sulfonate ester or a nitrogen-containing group if it has a negative charging property. Examples include media and metal-containing dyes. In the present invention, the suspension polymerization reaction is usually
The polymerization temperature is 50 ° C. or higher, and the temperature is set in consideration of the decomposition temperature of the polymerization initiator. If the set temperature is too high, the polymerization initiator will be rapidly decomposed and the molecular weight and the like will be affected. In addition, neutral salts such as sodium chloride and sodium sulfate may be added to the aqueous medium for the purpose of preventing emulsification. Further, a thickener such as glycerin or ethylene glycol may be added for the purpose of preventing coalescence of the monomer composition particles formed in the granulation step.

As the polymer A, various kinds of polymers described in paragraph 17 are used, and among them, it is preferable to use at least one kind of epoxy resin and polyester resin. The inventors of the present invention have found that, when these polymers A are used, the mechanical strength of the toner becomes very good.

In the usual suspension polymerization, all the droplets of the toner composition as a suspension are spherical. In the present invention, the suspension obtained in the granulation step is passed through the granulation step a plurality of times under appropriate heating conditions, which is one of the objects of the present invention. A non-spherical group of toner particles can be obtained.

At this time, above the decomposition temperature of the polymerization initiator,
It is necessary to warm the suspension. As described above, the heating condition does not cause any problem as long as it is equal to or higher than the decomposition temperature of the polymerization initiator, but it is desirable from the viewpoint of spherical control in a shorter time.
The granulation step in the present invention is not limited to a particular method, as long as the suspension is subjected to a constant stress field. Examples include "TK Homo Mixer" manufactured by Tokushu Kika Co., Ltd., "Defoaming Mixer" manufactured by Homogenizer Shinky Co., Ltd., and the like.

Further, in the present invention, the general formula CH ₂ = C
HCOO (CH ₂ ) _n CH ₃ (where n is an integer of 10 to 18) ... A compound represented by the formula (1) and a graft polymer obtained by reacting a polymerizable monomer are contained. Characterize.

The first reason for using the graft polymer is to prevent the offset phenomenon between the roller and the toner in the heat fixing roller. However, n is 10
When it is less than 1, a sufficient releasing effect is obtained, but n is 1
When it exceeds 8, the compatibility of the compound of the formula (1) of the polymerizable monomer deteriorates, and the transparency is impaired especially when applied to a color toner. The compound of formula (1) is a polymerizable monomer 10
It is desirable that 0.5 parts by weight or more and less than 10 parts by weight be blended with 0 parts by weight. More preferably, 0.5 parts by weight or more and less than 5 parts by weight is suitable. If it is less than 0.5 part by weight, the releasing effect is lowered and the offset phenomenon is likely to occur. When it is 10 parts by weight or more, the compatibility of the compound of the formula (1) with the polymerizable monomer may be deteriorated and the transparency may be impaired.

The compound of the formula (1) used in the present invention is the compound of the formula (1) in the suspension polymerization method of the present invention.
The vinyl group of the polymer reacts with the polymerizable monomer and is grafted to the polymer of the polymerizable monomer to give good releasability to the toner, and at the same time, it is developed by being detached from the toner particles. It is possible to prevent contamination of the vessel. Further, as described above, since the compatibility is easy, the wax is not phase-separated in the toner particles, and good transparency can be obtained.
Both releasability and transparency can be realized. In addition,
As the compound of the formula (1), for example, the product name “ST-100” (n = 18) marketed by Nippon Shokubai Co., Ltd. is used in the present invention.

Further, in the present invention, after completion of the drying step, “Tg of polymer A ≦ heating temperature ≦ Tg of polymer A + 1”.
It is preferable to heat-treat the toner in the range of "0 ° C". Ultrafine particles having a particle size in the submicron region may be generated in the polymerization process. Although the generation mechanism of the ultrafine particles is not always clear, it is considered that highly hydrophilic composition components migrate from the suspension droplets into the continuous phase of the water tank and are generated. If the ultrafine particles remain mixed in the toner, they may be fused to the phase regulating member or the developing roller in the case of non-magnetic one-component development.

According to the results of the study conducted by the present inventors, after the completion of the drying step, the toner is heated within a range of Tg of the polymer A and Tg + 10 ° C. for an appropriate time, whereby the ultrafine particles are fixed on the toner surface. It was found that fusion to the layer regulating member of the developing device and the developing roller is eliminated.

Further, in the production method of the present invention, as described in paragraph 20, it is preferable that the polymer A does not contain a crosslinking component. Various external additives can be used for the electrostatic charge developing toner of the present invention mainly for the purpose of improving the fluidity thereof.
Specifically, in addition to metal oxide fine particles such as silica, alumina, titanium oxide, zinc oxide and magnetite, an aliphatic metal salt, silicone oil or the like can be used as a lubricant.

In addition to these, styrene polymer, styrene acrylate copolymer, methyl methacrylate (MMA)
Organic fine particles such as can be used as an external additive. In particular, when a metal oxide such as silica or alumina is used, it is desirable to mainly use those having a small primary particle diameter and to use a plurality of kinds of external additives having a larger particle diameter in combination.

According to the knowledge of the present inventors, the smaller the particle size of the external additive is, the more the fluidity of the developer is improved.
The mechanical stress that the toner receives from the layer regulating member also increases, and the external additive is likely to be buried in the toner surface. In this case, by using the external additive having a relatively large particle size in combination with the external additive having a small particle size, the embedding of the external additive in the toner surface is suppressed, and the fluidity is improved even during continuous imaging. Good electrophotographic properties with little deterioration are maintained.

As a means for adhering the external additive to the surface of the toner, the toner and the external additive are mixed in a predetermined ratio, and an agitator such as a turbine type agitator, a Henschel mixer or a super mixer is used. And a method of stirring. In the present invention, the term “external additive is attached to the surface of the toner” means that the external additive is sprinkled and attached to the surface of the toner and at least the external additive is attached to the surface of the toner. A state in which a part is buried and fixed. In this case, in order to bury and fix the external additive, a surface modification means such as a Nara hybridization system manufactured by Nara Machinery Co., Ltd. or an Ongmill manufactured by Hosokawa Micron Co., Ltd. is effective.

The toner for electrostatic charge development of the present invention has a volume average particle diameter of 12 μm or less, preferably 3 to 9.5 μm. If the volume average particle diameter is less than 3 μm, sufficient fluidity cannot be obtained. On the other hand, 9.5
If it is larger than μm, the reproducibility of pixels such as thin lines and characters deteriorates.

[0048]

In the toner used in the non-magnetic one-component developing method, the mechanical strength of the toner surface is high in order to prevent the toner from adhering to the layer regulating member and the developing roller, and the toner is locally localized. It is required to have a shape that is less susceptible to physical stress. However, if the mechanical strength of the toner surface is simply improved, the fixing property may be deteriorated depending on the thermal characteristics of the toner surface and the molecular weight design. On the other hand, regarding the toner shape, the mechanical stress that the toner receives in the developing portion can be reduced by rounding or spheroidizing, but the blade cleaning property tends to deteriorate. The present invention has been achieved by the background of such conventional techniques, and the summary thereof can be summarized into the following two points.

First, the toner for electrostatic charge development according to the suspension polymerization method, which constitutes the present invention, contains the specific polymer A in the dispersed phase,
That is, Tg is 55 to 80 ° C., and the flow softening point T
m is 95 to 155 ° C. and the number average molecular weight Mn is 300.
By including a polymer of 0 to 8000, preferably an epoxy resin or a polyester resin, it becomes possible to prevent the fusion of the toner and improve the fixability at the same time.

Secondly, in the present invention, the distribution of the degree of irregularity Ps of the toner particles and the shape Sf are controlled, and after the drying step, the toner is subjected to a heat treatment to convert the ultrafine powder in the submicron region into toner particles. It was possible to satisfy the requirements for elimination of fusion in the developing section and good blade cleaning property at the same time. From the effects of the first and second aspects of the present invention described above, the toner constituting the present invention has no fusing in the developing portion, and therefore has no problems such as fog and scattering, and has good blade cleaning properties. In addition, it has extremely good fixing property.

[0051]

EXAMPLES The present invention will be described below based on examples.
In addition, in an Example, a part shows a weight part. Again,
3 and 4 are explanatory views for explaining the manufacturing method of the present invention. In FIG. 3, 31 is a continuous phase tank, 32 is a dispersion phase tank,
33 is a polymerization tank, 34 is a metering pump, 35 is a granulator A 3,
5'is a granulator B, 36 is a condenser, 37 is a heating jacket, the polymerizable monomer and the colorant are in the dispersion phase tank 32,
A continuous phase composed of an aqueous medium is charged into the continuous phase tank 31,
It is sent by the metering pump 34 so as to have a constant ratio by another route. At that time, it is granulated by the granulator A35 , deformed by the granulator B35 ′, and guided to the polymerization phase 33.
A condenser 36 is provided at the upper part of the dispersion phase tank 32 and the polymerization tank 33 to prevent the volatile components from escaping.

FIG. 4 shows a granulator A used in the present invention.
In a typical example of the above, the dispersion liquid obtained in FIG.
More to the outside of the device. At the center of the upper part of the device, there is a rotary shaft 38, and at the lower part of the rotary shaft 38, there are a stirring blade 40, a shearing region 41, and a discharge control gap 42, so that the inside can be stirred. A dispersed phase supply port 44 is provided in the center and a continuous phase supply port 43 is provided around the dispersed phase supply port 44, and both are stirred by the stirring blade together with the dispersion liquid, and are made into fine particles by a shearing force. Examples and comparative examples using such a device will be described below.

Example 1 As a continuous phase, polyvinyl alcohol (manufactured by Tokyo Chemical Industry Co., Ltd., polymerization degree: about 2000, saponification degree: about 80%) was added to water in an amount of 1: 1.
%, Sodium sulfate was prepared to be an aqueous solution of 3% with respect to water, and the solution was placed in the continuous phase tank 31 shown in FIG. In addition, 4000 g of styrene as a dispersed phase, and butyl acrylate 1
The glass transition point Tg is 6 in the monomer composition consisting of 000 g.
The temperature is 8 ° C, the flow softening point Tm is 103 ° C, and the non-crosslinked polyester resin having a number average molecular weight Mn of 3400 is charged and dissolved, and then 40 g of 2,2'-azobisisobutyronitrile is dissolved. The mixed solution was prepared and copper phthalocyanine blue (manufactured by Sanyo Dye Co., trade name K
RG) 400 g was dispersed. Furthermore, 100 g of a charge control agent (trade name TN-1 manufactured by Hodogaya Chemical Industry Co., Ltd. was added to this mixed solution.
05) and the compound represented by the formula (1) (n = 15 to 1)
200 g of 8) was added and dispersed for 30 minutes by an ultrasonic disperser. This mixed solution was put into the dispersion phase tank 32 shown in FIG. Next, the dispersed phase (monomer composition) was supplied to the granulator A 35 at a flow rate of 100 ml / min and the continuous phase at a flow rate of 400 ml / min for 10 minutes. A granulator A 35 having a rotating part with a diameter of 50 mm was used, and the mixed liquid of the dispersed phase and the continuous phase was stirred under the condition of 10000 rpm, and the average of 8 μm was observed by a transmission measuring microscope. Droplet groups were obtained.

The suspension obtained by the above operation was
After heating to ℃, granulator B35 ' (HX manufactured by Shinky Co.
-201) and stirred for 20 minutes. Then, the dispersion liquid,
Led into the polymerization tank 33 shown in FIG. 3, 3 in turbines type stirring blade
With stirring was allowed to react for 8 hours et at rpm. Thereafter, the polymer particles were separated by a centrifugal dehydrator, washed thoroughly with water and then dried. The obtained particles were heated at 73 ° C. for 3 hours, and then 10 g of hydrophobic silica (H-2000 / 4, manufactured by Hoechst Co., Ltd.) as a fluidity improver was added to 2000 g of the particles, and the particles were mixed with a Henschel mixer to obtain 2 After stirring for a minute, an electrostatic charge developing toner according to the present invention was obtained.

The residue derived from the polymerization initiator of the obtained toner was 35 ppm. Also, Ps showing the maximum frequency
Is 1.3, the ratio of Ps1.5 or more is 2.3%,
Ps of 2.0 or more was 4.0% by number. The shape factor Sf was 0.81. The volume average particle diameter (d50% diameter) of the obtained toner was 6.9 μm.

Example 2 As polymer A, an epoxy resin having a glass transition point Tg of 62 ° C., a flow softening temperature Tm of 110 ° C. and a number average molecular weight Mn of 3500 was used, and the heating temperature after drying was 67 ° C. In the same manner as in Example 1, an electrostatic charge developing toner of the present invention was obtained. The residue derived from the polymerization initiator of the obtained toner was 45 ppm. The maximum frequency Ps is 1.
25, the ratio of Ps1.5 or more is 19.5%, Ps
2.0% was 3.6 number%. The volume average particle diameter (d50% diameter) of the toner was 7.1 μm.

Example 3 As the polymer A, a polyester resin having Tg of 68 ° C., a flow softening point of 135 ° C. by a Koka type flow tester, and a number average molecular weight of 5500 by GPC was used. A toner for electrostatic charge development of the present invention was obtained in the same manner as in Example 1 except that the temperature was set to 75 ° C. The residue derived from the polymerization initiator of the obtained toner was 41 ppm.
The maximum frequency Ps is 1.4, the ratio of Ps1.5 or more is 24.1%, and the ratio of Ps2.0 or more is 4.7.
%Met. The volume average particle diameter of the toner (d50%
The diameter) was 7.3 μm.

Comparative Example 1 A comparative electrostatic charge developing toner was obtained in the same manner as in Example 1 except that the polymer A was not used and the heat treatment after drying was not performed.

Comparative Example 2 The same procedure as in Example 1 was carried out except that a polyester resin having a glass transition point Tg of 53 ° C., a flow softening point of 91 ° C. and a number average molecular weight Mn of 3100 was used and the heating temperature was 63 ° C. Thus, a toner for electrostatic charge development for comparison was obtained.

Comparative Example 3 Glass transition point Tg is 85 ° C. and flow softening point Tm is 162.
A comparative electrostatic charge developing toner was obtained in the same manner as in Example 1 except that a polyester resin having a temperature of 90 ° C. and a number average molecular weight Mn of 8400 was used and the heating temperature was 90 ° C.

Example 4 A toner for electrostatic charge development of the present invention was obtained in the same manner as in Example 1 except that heating after drying was not performed.
It was found from SEM confirmation that a small amount of particles in the submicron region were mixed in this, but there was no practical problem.

Comparative Example 4 CH ₂ = CHCOO (CH ₂ ) _n CH ₃ (n is 10 to 1)
Except that it does not contain the graft polymer over that obtained by reacting the 8 integer) and the polymerizable monomer in Example 1
A toner for electrostatic charge development of Comparative Example 4 was obtained in the same manner as in.

By the above operation, a commercially available laser beam printer LP1 is used by using the electrostatic charge developing toner obtained.
A print test was conducted using a 060 SP-3 machine (manufactured by Ricoh Company). None of the toners for developing electrostatic charge of Examples 1 to 4 was fused to the layer regulating member to such an extent that the developer would hinder practical use. The evaluation results are shown in Table 1 below.

[0064]

[Table 1]

Here, each evaluation item is: Image density: The solid image area was measured with a Macbeth reflection densitometer. 2. Fog: The difference in whiteness of the non-image area before and after printing was measured with a Hunter color difference meter. 3. Fusing: The state of fusing of the toner to the layer regulating member and the developing roller was observed using an optical microscope, and judged according to the following criteria. ◯: No fusion was observed after 3000 sheets were imaged. Δ: Some fusion occurred on either the layer regulating member or the developing roller after 3,000 sheets were taken, but this was not a problem for practical use. No streaks in the process direction are recognized. X: After capturing 3000 sheets, streaks in the process direction occur in the layer regulation member and the front surface image.

4. Cleanability ◯: No toner slips through the blade due to poor cleaning even after imaging 3000 sheets. X: In 3000 sheets of imaging, defective cleaning occurs, and image defects due to defective cleaning are recognized.

5. Fixability Fixability is evaluated by a commercially available copying machine (Sharp SF83
No. 00) was used, and an external fixing device obtained by modifying a fixing unit used for the fixing was used. For the unfixed test piece, commercially available two-component development was used. It was manufactured by a copying machine (trade name Z-133 manufactured by Sanyo Electric Co., Ltd.). ◎ Non-offset temperature range: 95 mm / s without oil
The peripheral speed of the fixing heat roller was fixed to ec, the temperature applied to the roller was varied between 110 ° C. and 220 ° C., and the temperature range in which offset did not occur was taken as the non-offset temperature region. The image pattern was a solid band pattern in the rear direction with respect to the fixing direction. * Fixing strength: An unfixed image was picked up using a gradation pattern and fixed under the same conditions as the fixing offset. However, the fixing temperature was 160 ° C. 1 kg of the obtained fixed image
It was rubbed 5 times with a sand eraser under a pressure of / cm ² . The image density before rubbing (X) and the image density after rubbing (Y) were measured with a Macbeth reflection densitometer, and the fixing strength was calculated from the following formula. Fixing strength (%) = (Y / X) × 100

6. Smoke emission Phenomenon was observed when confirming the fixing offset, but no smoke was emitted (○).

[0069]

According to the present invention, by blending the specific polymer in the toner by the suspension polymerization method as described above, there is no fusion to the developing member, and the blade cleaning property and the fixing property are good. It is possible to obtain excellent toner characteristics.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a non-contact type non-magnetic one-component developing device for carrying out the present invention.

FIG. 2 is an example of a sectional view of toner particles obtained by analyzing and modeling the electrostatic charge developing toner of the present invention.

FIG. 3 is an explanatory view showing an example of a polymerization apparatus used in the present invention.

FIG. 4 is an explanatory view showing an example of a granulator A used in the present invention.

[Explanation of symbols]

11 toner particles 21 photoconductor drum 22 hopper 23 electrostatic charge developing toner 24 layer control member 25 developing roller 26 leak prevention member 27 agitator 31 continuous phase tank 32 dispersion phase tank 33 polymerization tank 34 metering pump 35 granulator A 35 'granulation Granulator B 36 Condenser 37 Heating jacket 38 Rotating shaft 39 Dispersion liquid discharge port 40 Stirring blade 41 Shearing region 42 Emission control gap 43 Continuous phase supply port 44 Dispersion phase supply port 45 Heating stirrer

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masayu Kurosaki 3-1, Somune-cho, Shizuoka-shi, Shizuoka Pref., Technical Research Institute, Tomagawa Paper Mills Co., Ltd. (56) Reference JP-A-10-48885 (JP, A) JP-A-9-43896 (JP, A) JP-A-9-15900 (JP, A) JP-A-8-305074 (JP, A) JP-A-4-1766 (JP, A) JP-A-6 -128305 (JP, A) JP-A-6-128306 (JP, A) JP-A-6-157619 (JP, A) JP-A-60-123861 (JP, A) (58) Fields investigated (Int.Cl) . ⁷ , DB name) G03G 9/087

Claims (8)

(57) [Claims] 1. A polymerizable monomer _CH 2 = CHCOO
(CH ₂ ) _n CH ₃ (where n is an integer of 10 to 18),
A toner for electrostatic charge development, comprising a dispersed phase containing another polymerizable monomer, a colorant and a polymer A, and a continuous phase composed of an aqueous medium, which are mixed in a controlled ratio, and then dried after polymerization. , The glass transition point Tg of the polymer A is 55 to 80 ° C.,
The flow softening temperature Tm by the Koka type flow tester is 95.
~ 155 ° C, GPC number average molecular weight Mn of 3000
The toner for electrostatic charge development is characterized in that 2. The toner for electrostatic charge development according to claim 1, wherein the polymer A is at least one kind of epoxy resin and polyester resin. 3. The toner for electrostatic charge development according to claim 1, wherein the polymer A does not contain a crosslinking component. 4. The electrostatic charge developing toner according to claim 1, wherein the residual amount of the polymerization initiator is 1000 ppm or less. 5. The radius of the minimum circumscribed circle of the toner particles is Rl,
When the radius of the maximum inscribed circle of toner particles is Rs, Ps =
Deformation degree Ps represented by Rl / Rs is 1.1 or more 1.4
The maximum frequency exists in the following range, 10% by number or more of toner particles having Ps of 1.5 or more, 3% by number or more of toner particles having Ps of 2.0 or more, and further projection of toner particles When the area is S and the perimeter of the toner particles is 1,
5. The projected area (shape factor) Sf of the toner particles represented by Sf = (4πS) / l ² is in the range of 0.65 ≦ Sf ≦ 1.0. Toner for electrostatic charge development. 6. CH ₂ ═CHCOO as the polymerizable monomer
(CH ₂ ) _n CH ₃ (where n is an integer of 10 to 18),
The dispersed phase containing the other polymerizable monomer, the colorant, and the polymer A and the continuous phase composed of the aqueous medium were held in independent tanks, respectively, and both were controlled through independent paths. The mixture is continuously supplied to the granulator at a ratio to prepare a suspension having polymerizable droplet groups of a desired size, and the suspension is introduced into a polymerization tank to cause a polymerization reaction and then dried. And a glass transition point Tg of the polymer A is 55 to 80 ° C., and a flow softening temperature Tm by a Koka type flow tester is 95 to 155 ° C. Yes, GPC number average molecular weight Mn
Is 3000 to 8000. A method for producing a toner for electrostatic charge development, characterized in that 7. The glass transition point T of the polymer A after the drying step.
7. The method for producing an electrostatic charge developing toner according to claim 6, wherein the heat treatment of the toner is performed in a temperature range of g or more and Tg + 10 ° C. or less. 8. The method for producing an electrostatic charge developing toner according to claim 6, wherein the polymer A does not contain a crosslinking component.