JPH07319208A - Positive charge type developing toner - Google Patents

Abstract

PURPOSE:To produce a toner which hardly causes a toner spent due to generation of particulates and is usable most suitably for an electrophotographic copying machine having a toner recycling mechanism. CONSTITUTION:This toner is composed of at least binder resin component, colorant and positive charge type additive, and this binder resin component is composed of 60-90wt.% polyester component and 40-10wt.% styren-acryl component, and in the polyester component, hydroxy value (OHV) is 10-50, acid value (AV) is 10-50, ratio of the hydroxy value to the acid value OHV/AV is more than 0.5 and less than 2.0, and in a mol.wt. distribution calculated by a gel permeation chromatography, wt. average mol.wt. is 20,000 80,000, and in the styren-acryl component, the component has carboxyl group in a side chain of high polymer, and at least one peak or shoulder at a region of mol.wt. of 2-5 million in the mol.wt. distribution calculated by the gel permeation chromatography.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic charge image developing toner for electrophotography and the like.

[0002]

2. Description of the Related Art Conventionally, in the electrophotographic process, which is the most common electrostatic image developing method, an electrostatic latent image is formed on the surface of a photoconductor by charging and exposing, and then toner is electrostatically adhered to the latent image. And develop. The obtained toner image is electrostatically transferred again to an image carrier such as paper and finally fixed on the image carrier as a permanent image by a heat roll. Further, the toner remaining on the photoconductor in the toner transfer step is removed from the photoconductor by the cleaning blade after the charge removal of the photoconductor and collected.
In recent years, from the viewpoint of environmental protection, a toner recycling mechanism has been adopted in which the transfer residual toner is directly put into a toner supply box and reused for image formation.

In recent years, the copying machine performance has been remarkably improved, and a copying machine having higher image quality, higher speed, and higher durability has been required. In order to meet these requirements, it is necessary to drastically improve the toner performance not only as a machine but also as a developer.

In a copying machine having a toner recycling mechanism, it is required that the charge amount of the toner as a developer does not change and that the toner is hardly ground in the developing machine. The toner whose charge amount has decreased in the developing, transferring and recycling steps is mixed with the developer, which causes toner scattering and image fogging in the developing machine. In order to prevent a decrease in the amount of charge, it is necessary to use a toner that does not easily release the external additive. It is also possible to add a charge control agent directly to the inside of the toner to reduce the change in toner charge amount before and after recycling, but such internal additives often contain harmful substances such as nigrosine, which is environmentally friendly. Not preferable from a viewpoint. Further, there is a problem that many toners are very expensive, which causes an increase in toner cost.

When the toner is ground in the developing device to generate so-called toner fine powder, the toner fine powder is hard to be transferred as compared with the toner having a normal particle size because of its large physical adhesion to the photoconductor in the toner transfer process. . Therefore, the toner fine powder is selectively recycled, and the toner fine powder in the developing machine increases. The toner fine powder serves as an attractant for carrier spent in the two-component developer, and serves as an attractant for sleeve contamination and the like in the one-component developer. As a result, the increase in the amount of fine powder toner causes fogging and toner scattering.

Conventionally, many toners using styrene-acrylic resin as a binder resin have been proposed as means for preventing the toner from being ground in the developing machine. Certainly, some of these toners have good charging performance and abrasion resistance. However, when combined with a positively chargeable external additive, the triboelectric charging sequence between the toner base and the positively chargeable external additive is close, so the electrostatic attraction between the toner surface and the external additive is small, and the external additive does not come off. Cause Although many toners using a polyester resin as a binder resin have been proposed, the polyester resin has a low positive charging property, and a good charging property cannot be obtained only with the polyester resin.

[0007] Therefore, a toner which is not ground in the developing machine, does not cause toner spent or sleeve contamination due to generation of fine powder, has good chargeability, has a small amount of external additive detachment, and is excellent in recycling property is provided. To obtain it, it is conceivable to use a composite of styrene-acrylic resin and polyester resin as the binder resin.

Japanese Unexamined Patent Publication No. 54-114245 discloses a molecular weight of 1,000 to
A mixture of 4,000 low melting polyester polymers and a macromolecular vinyl polymer with a weight average molecular weight of 500,000 or more has been proposed. However, the technology described in this publication does not take recycling characteristics into consideration, and after dry blending a styrene-acrylic polymer having no reaction points with the polyester polymer, it is only melt-kneaded. Since the dispersion of the styrene-acrylic polymer is poor and the content ratios of both polymers are different among the toners, the chargeability is not uniform among the toners. Further, the portion of the toner where only the polyester polymer is present serves as a crushing point in the developing machine, and toner fine powder is produced.

Japanese Patent Application Laid-Open No. 4-69666 discloses a toner in which a binder resin has peaks at molecular weights of less than 30,000, 30,000 to 1,000,000, and more than 1,000,000 in the molecular weight distribution measured by gel permeation chromatography. Is proposed. However, the technique of this publication also does not take recycling characteristics into consideration, and in addition, since it is a mixture of polyester resin and styrene-acrylic resin having no reaction point, a problem of poor dispersion of both resins occurs.

JP-A-2-29664 discloses a uniform dispersion obtained by copolymerizing vinyl monomer (C) and polyester (A) copolymerizable with (C) in polyester (B). Binder resins have been proposed. The technique of this publication also does not take recycling characteristics into consideration, and since the vinyl monomer is polymerized in the presence of saturated polyester and unsaturated polyester, the molecular weight and the reactivity of unsaturated polyester and vinyl resin and the dispersion state It is not preferable in terms of manufacturing stability because it is difficult to control.

Japanese Patent Laid-Open No. 5-880403 discloses that a binder resin is composed of polyester and a vinyl polymer, has no tetrahydrofuran (THF) insoluble matter, and has a molecular weight measured by gel permeation chromatography of a THF soluble matter. In distribution, weight average molecular weight 10,000 to 20
A toner having a number average molecular weight of 0.00000, a number average molecular weight of 1,000 to 10,000, and containing 5 to 15% by weight of a component in the molecular region of 1 × 10 ⁷ or more has been proposed. However, when such a toner is used as a normal-electricity toner, since the polyester and the vinyl polymer are compatible with each other, the external additive holding ability is weak and the external additive is dislocated, resulting in poor recycling characteristics.

[0012]

A mixture of polyester resin and styrene-acrylic resin can be preferably used for a copying machine having a toner recycling mechanism from the viewpoint of recycling characteristics. However, in the case of blending resins having no reaction points, there arises a problem of uneven charging between toners due to poor resin dispersion. In the method of polymerizing vinyl monomer in the presence of saturated polyester resin and unsaturated polyester resin, it is difficult to control the reactivity, molecular weight and dispersion state of polyester resin and vinyl resin, so that toner with good abrasion resistance can be stabilized. There is a problem that you can not get it. Therefore, the object of the present invention is to solve the above-mentioned problems, in which the chargeability between the toners is uniform, there is no weakly charged toner, the external additive does not come off before and after the toner recycling, and it is not ground in the developing machine and fine powder. It is an object of the present invention to provide a toner that can be optimally used in an electrophotographic copying machine having a toner recycling mechanism without generating a toner spent due to generation.

[0013]

As a result of intensive studies, the inventors of the present invention have reached the present invention as a toner that solves the above problems. That is, the present invention has the following configurations.

In a positively chargeable developing toner used in an electrophotographic copying machine having a toner recycling mechanism, the toner comprises at least a binder resin component, a colorant and a positively chargeable external additive, and the binder resin component is a polyester component. It is composed of 60 to 90% by weight and 40 to 10% by weight of styrene-acrylic component, and has a hydroxyl value (O
HV) is 10 to 50, acid value (AV) is 10 to 50, the ratio of hydroxyl value to acid value, OHV / AV is 0.5 or more and less than 2.0, and molecular weight distribution measured by gel permeation chromatography. Has a weight average molecular weight of 20,000 to 80,0
00, the styrene-acryl component has a carboxyl group in the polymer side chain, at least one peak or shoulder in the region of molecular weight 2 million to 5 million in the molecular weight distribution measured by gel permeation chromatography. A positively-chargeable developing toner, which has three characteristics.

An example of the toner recycling system according to the present invention is shown in FIGS.

In this example, 1 is a developing device, 2 is a developing sleeve, 3 is a photoconductor, 4 is a cleaning device, 5 is a toner carrying screw 1, 6 is a toner carrying screw 2, 7 is a toner carrying screw 3 and 9 is toner. It is a supply box. In the apparatus of this example, the toners collected in the cleaning section are sequentially conveyed by the toner conveying screws 1, 2, and 3 to a distributor 8 (separate from the New toner supply port) dedicated to the collected toners provided in the developing device. It is designed to be supplied.
That is, the toner transport screw 1 of 5, the toner transport screw 2 of 6 and the toner transport screw 3 of 7 each have a rotating shaft inside and a blade spirally provided along the rotating shaft, and the toner rotates. The toner is sequentially conveyed by the blades as the shaft rotates, is supplied to the distributor 8, and the collected toner is used again for latent image development on the photoconductor 3.

On the other hand, 1 to 7 and 9 in FIG. 2 are the same as in FIG.
In the apparatus of this example, toner collected by the cleaning section is successively conveyed by the toner conveying screws 1, 2 and 3 and supplied to the toner supply box. This example is different from FIG. 1 in that the new toner and the recycled toner collected in the toner supply box are agitated and mixed in advance and then supplied to the developing device.

In the binder resin of the toner of the present invention, it is preferable that the polyester component has a --OH group at the terminal and the styrene-acrylic component has a --COOH group in the side chain. Since the two components have the above-mentioned polar group, the polar groups partially react with each other when these components are mixed,
Since the compatibility of the two components is improved, the dispersibility is improved.

In the present invention, the mixing of the styrene-acrylic component and the polyester component is preferably carried out in a solution or after dry blending with another toner composition and at the time of melt kneading. In particular, it is more preferable that they are mixed in a solution to obtain a desired dispersion diameter.

As the polyester component in the present invention, a polyester obtained by polycondensing a polyhydric alcohol and a polybasic acid can be used. Polyhydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,
Saturated aliphatic glycols such as 6-hexanediol and their alkylene oxides (ethylene oxide,
Propylene oxide, etc.) adducts, hydroquinone, catechol, resorcin, pyrogallol, bisphenols (bisphenol A, bisphenol F, bisphenol sulfone, etc.) and hydrogenated bisphenols such as alkylene oxide (ethylene oxide, propylene oxide, etc.) adducts and other phenolic compounds Glycerol, glycerin, trimethylolpropane, trimethylolethane, hexanetriol, pentaerythritol, diglycerin, α-methylglucoside, sorbitol, xylit, mannitol, glucose, fructose, sucrose, and other saturated trivalent to octavalent fatty acids Alcohols and their alkylene oxide (ethylene oxide, propylene oxide, etc.) adducts, alkanolamines (triethanolamine) Tripropanolamine, etc.), alkylenediamine (ethylenediamine, hexamethylenediamine, etc.), polyalkylenepolyamine (diethylenetriamine, triethylenetetraamine, etc.), aromatic amine (aniline, phenylenediamine, etc.), alicyclic amine (isophoronediamine, cyclohexyl) Examples thereof include methanediamine and the like), heterocyclic amine (biperazine, aminoethylbiperazine, and the like) and the like, and an amino group-containing polyhydric alcohol in which an alkylene oxide is added, and a mixture of two or more thereof. Among these, ethylene glycol, neopentyl glycol, alkylene oxide adducts of bisphenols, and mixtures thereof are preferably used.

As the polybasic acid, malonic acid, succinic acid,
Saturated aliphatic dibasic acids such as adipic acid, azelaic acid, sebacic acid, octylsuccinic acid and cyclohexanedicarboxylic acid, and aromatic dibasic acids such as phthalic acid, isophthalic acid and terephthalic acid, trimellitic acid, 1,2,4 -Cyclohexanedicarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,
Polybasic acids such as 2,5-hexanetricarboxylic acid, pyromellitic acid and benzophenonetetracarboxylic acid, and their anhydrides and lower alkyl esters can also be used. Among these, succinic acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, alkylsuccinic acid and the like are preferably used.

The polyester component used in the present invention has an acid value of 10 to 50 and a hydroxyl value of 10 to 50, and it is preferable that the acid value and the hydroxyl value satisfy the following formula.

0.5 <OHV / AV <2.0 (AV; acid value of polyester component, OHV; hydroxyl value of polyester component) If OHV / AV is 0.5 or less, the number of reaction points with -COOH groups in the styrene-acrylic component decreases, OHV / which causes poor dispersion of styrene-acrylic component and polyester component
When AV is 2.0 or more, a large amount of --OH groups remain in the toner, and the toner charging property becomes unstable.

Here, the acid value means the number of milligrams of potassium hydroxide necessary for neutralizing the acid contained in 1 g of the sample. Further, the hydroxyl value means the number of milligrams of potassium hydroxide necessary for neutralizing acetic acid bound to a hydroxyl group when acetylating 1 g of a sample according to the standard method for analyzing fats and oils (edited by Japan Oil and Fat Science Association).

The polyester component in the present invention preferably has a weight average molecular weight of 20,000 to 80,000 in the molecular weight distribution measured by gel permeation chromatography. Weight average molecular weight of polyester component
If it is less than 20,000, the mobility of the molecular chain of the polyester component becomes too large, resulting in poor dispersion. Also, the aggregation resistance of the toner is deteriorated. Grinding performance of 80,000 or more,
Fixing performance deteriorates.

The styrene-acrylic resin in the present invention includes a styrene monomer and / or an acrylic acid ester or a methacrylic acid ester monomer, and acrylic acid or methacrylic acid as a component having a --COOH group in the side chain. Copolymers of acid monomers can be used.

Examples of the styrene-based monomer include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-ethylstyrene and 2,3
-Dimethylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene,
pn-decylstyrene, pn-dodecylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene,
Mention may be made of 3,4-dichlorostyrene and the like. Of these, styrene is preferable.

Examples of acrylic acid ester or methacrylic acid ester monomers include methyl acrylate,
Ethyl acrylate, propyl acrylate, acrylic acid-n
-Butyl, isobutyl acrylate, -n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, methacrylic acid
-n-butyl, isobutyl methacrylate, methacrylic acid -n-
Acrylic acid or alkyl esters of methacrylic acid such as octyl, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, acrylic acid-2
-Chloroethyl, phenyl acrylate, methyl α-chloroacrylate, phenyl methacrylate, dimethylaminophenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate and the like can be mentioned. Among these, ethyl acrylate, propyl acrylate-n-butyl acrylate, ethyl methacrylate, propyl methacrylate, methacrylic acid-n-butyl, and the like are preferable acrylic acids or alkyl esters of methacrylic acid, and particularly acrylic acid-n. -Butyl, methyl methacrylate,
Preferred is n-butyl methacrylate.

Acrylic acid and methacrylic acid are preferred as the acrylic acid and methacrylic acid type monomers.

Solution polymerization, suspension polymerization, emulsion polymerization and bulk polymerization are used for the polymerization of the styrene-acrylic component. Among these, suspension polymerization is most preferably used in order to obtain a high molecular weight component with high reproducibility.

As the polymerization initiator of the styrene-acrylic component, acetyl peroxide, lauroyl peroxide, benzoyl peroxide, and other diacyl peroxides, cumene hydroperoxide, and other hydroperoxides, di-tert-butyl peroxide, and the like are used. Azo compounds such as alkyl peroxides and 2,2-azobisisobutylisobutyronitrile can be used. Among these, benzoyl peroxide and 2,2-azobisisobutyronitrile are preferably used.

The addition amount of these polymerization initiators is preferably 0.01 to 10 parts by weight with respect to 100 parts by weight of the monomer.

In the present invention, the monomer having a --COOH group contained in the styrene-acrylic resin component is preferably contained in the styrene-acrylic component monomer in an amount of 1 to 10% by weight. If the content of the --COOH group-containing monomer is less than 1% by weight, the dispersibility with the polyester component is deteriorated. If it exceeds 10%, the functional separation structure due to the polyester component and the styrene-acrylic component will not appear.

The styrene-acrylic component of the binder resin component in the present invention preferably has at least one peak or shoulder in the range of 2 to 5 million gel permeation chromatography. When the peak or shoulder of the styrene-acrylic component is less than 2 million, it is impossible to prevent the toner from being ground in the developing device. If it is present in excess of 5 million, the viscosity of the styrene-acrylic component becomes too high, resulting in poor dispersion with the polyester component and colorant.

In the binder resin component of the present invention, the weight ratio of styrene-acrylic component is 4 based on the binder resin.
It is preferably from 0 to 10% by weight. When the weight ratio of the styrene-acrylic component exceeds 40% by weight, the polyester as the external additive holding component is decreased, so that it is impossible to prevent the positively chargeable external additive from coming off during toner recycling. If the amount is less than 10% by weight, it is impossible to prevent the toner from being ground in the developing machine, and it is not possible to obtain a sufficient positive charging property.

In the present invention, the molecular weight is measured as follows.

The resin and tetrahydrofuran (THF) are mixed at a concentration of about 0.5 to 5 mg / ml (for example, 5 mg / ml) and stirred sufficiently to mix the THF and the resin well (until the solid resin disappears) at room temperature. Let stand for 1 hour. After that, the solution passed through a sample processing filter (pore size 0.45 micron, Tosoh GC-Chromatodisc) was used as a sample, and was measured by gel permeation chromatography (Tosoh "GC-8020"), and its integration was performed. The value is the molecular weight of the resin.

In the toner of the present invention, the polyester component and the styrene-acrylic component are mixed in a solvent in which both components are soluble. Or with other toner compositions,
It may be performed during melt-kneading after dry blending. From the viewpoint of production stability, it is particularly preferable to mix them in a soluble solvent for both components.

In the toner of the present invention, it is preferable that the styrene-acrylic component is uniformly dispersed in a stripe pattern with respect to the polyester component. This is because the two components are uniformly dispersed to form microdomains, so that a function-separated structure of a styrene-acrylic component as a positive chargeability imparting component and a polyester component as an external additive holding component is developed.

In the toner of the present invention, the dispersion diameter of the polyester component with respect to the styrene-acrylic component is 0.01 to 0.3 μm.
It is preferably m or less. If it exceeds 0.3 μm, the amount of the polyester component present on the toner surface becomes uneven between the toners, and the chargeability between the toners becomes uneven, resulting in a weakly charged toner. In addition, the recycling characteristics are also adversely affected. If it is less than 0.01 μm, the function-separated structure of the styrene-acrylic component as the positive charging property imparting component and the polyester component as the external additive holding component will not be exhibited.

[0041]

The other additives contained in the toner of the present invention will be described. As the wax, a low molecular weight polyolefin such as polypropylene or polyethylene and its derivative, an alkylenebisfatty acid amide compound, a paraffin wax or a combination of two or more of them. Those used are preferably used. The content of this wax is preferably 1 to 20 parts by weight, and particularly preferably 2 to 15 parts by weight, based on 100 parts by weight of the binder resin.

Examples of the colorant used in the toner of the present invention include carbon black, nigrosine dye, aniline blue, chalco oil blue, chrome yellow, ultramarine blue, DuPont oil red, Orient oil red, quinoline yellow, methylene blue chloride, and phthalocyanine. Examples include blue, malachite green oxalate, lamp black, and rose bengal.

In the present invention, the positively chargeable external additive has a blow-off charge amount of 10 to 1000 μC after mixing and stirring with iron powder.
/ G. More preferably 20-600 μC / g
Is.

As the positively chargeable external additive used in the toner of the present invention, hydrophobized metal oxides such as silica, alumina and titania, or a combination of two or more of these is preferably used. .

As the hydrophobic treatment agent for these metal oxides, an amino-modified silane coupling agent is preferably used in order to enhance the positive chargeability.

Preferred examples include γ- (2-aminoethyl) aminopropyltrimethoxysilane and γ- (2
-Aminoethyl) aminopropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, N
Examples include -β- (N-vinylbenzylaminoethyl) γ-aminopropyltrimethoxysilane hydrochloride and aminopropyltriethoxysilane.

The number average primary particle diameter of the positively chargeable external additive used in the toner of the present invention is preferably 0.01 to 0.5 μm. If it exceeds 0.5 μm, the exfoliation of the external additive in toner recycling deteriorates, and if it is less than 0.01 μm, the external additive easily forms aggregates and exfoliation of the external additive worsens. The number average primary particle size of the external additive is the number average primary particle size observed by an excess type or photographic electron microscope.

Further, for the purpose of further improving the cleaning property, fatty acid metal salts such as zinc stearate, calcium stearate and stearic acid, for example, polymer particles such as methyl methacrylate particles and styrene particles are added to the toner of the present invention. It may be mixed.

As the carrier constituting the two-component developer, either an uncoated carrier composed only of magnetic material particles such as iron and ferrite, or a resin coated carrier in which the magnetic material particle surfaces are coated with a resin or the like can be used. Good. The volume average particle diameter of the carrier is preferably 30 to 150 μm.

The toner of the present invention is manufactured as follows.

The binder resin component, the colorant, the wax and, if necessary, the magnetic powder are dry blended, melt-kneaded by an extruder, kneader, kneading roll machine, closed mixer, etc., and after cooling, finely kneaded by a jet mill, turbo mill or the like. Crush,
It can be obtained by dry-blending a classified toner having a predetermined particle size after classification, a positively chargeable external additive and, if necessary, a cleaning aid.

[0052]

The present invention will be described in detail below with reference to examples, but the embodiments of the present invention are not limited thereto.

(Production of External Additive) <Production of Positively Chargeable External Additive 1> Hydrophilic silica having a number average particle diameter of 12 nm is treated with aminopropyltriethoxysilane to give a positive chargeability of a number average particle diameter of 12 nm. External additive 1 was obtained. The charge amount of this positively chargeable external additive was measured with a blow-off type charge amount measuring device and was found to be 500 μC / g.

<Production of Positively Chargeable External Additive 2> Number average particle size
16 nm hydrophilic aluminum oxide was treated with aminopropyltriethoxysilane to obtain a positively chargeable external additive 2 having a number average particle diameter of 12 nm. In addition, the amount of charge of this positively chargeable external additive was measured with a blow-off type charge amount measuring device and found to be 50 μm.
It was C / g.

<Production of Negatively Chargeable External Additive 1> Number Average Particle Size
12 nm hydrophilic silica was treated with dimethyldichlorosilane to obtain a negatively chargeable external additive 1 having a number average particle diameter of 12 nm. The charge amount of this positively chargeable external additive was measured by a blow-off type charge amount measuring device and found to be -500 μC / g.

(Synthesis of Polyester Component) <Synthesis of Polyester 1> 160 parts by weight of terephthalic acid, 32 parts by weight of succinic acid, 289 parts by weight of bisphenol A / propylene oxide, 114 parts by weight of bisphenol A / ethylene oxide are thermometers, stainless steel. Stirrer,
Add to a 4-neck round bottom flask equipped with a glass nitrogen gas inlet tube and a flow-down condenser, set this flask in the mantle heater, and introduce nitrogen gas from the nitrogen gas inlet tube to create an inert atmosphere inside the flask. The temperature was raised while maintaining the temperature, then 0.05 part by weight of dibutyltin oxide was added and reacted at a temperature of 200 ° C, then 25 parts by weight of trimellitic acid was added and further reacted, and measured by gel permeation chromatography. Weight average molecular weight
The reaction is terminated when it reaches 32,000, and polyester 1
(A-1) was obtained.

With respect to the obtained resin, AV (acid value), OH
When the V (hydroxyl value) was measured, the OHV / AV was 1.2.

<Synthesis of Polyesters 2 and 3 and Comparative Polyesters 1 to 4> Polyesters 2 and 3 (A-2, 3) and Comparative Polyesters 1 to 4 were prepared in the same manner as Polyester 1.
(A-4 to 7) were synthesized. Table 1 shows the monomer composition,
The weight average molecular weight measured by gel permeation chromatography and OHV / AV are described.

[0059]

[Table 1]

(Synthesis of styrene-acrylic component) <Synthesis of styrene-acrylic 1 (B-1)> 68 parts by weight of styrene monomer, 28 parts by weight of butyl acrylate monomer, 4 parts by weight of methacrylic acid monomer, 0.3 parts by weight of polyvinyl alcohol, 200 parts by weight of degassed water and 0.09 parts by weight of benzoyl peroxide are mixed and suspended to heat the suspension dispersion, and the temperature is 78 ° C. in a nitrogen atmosphere.
Was reacted for 30 hours to carry out suspension polymerization to obtain styrene-acrylic 1 (B-1).

When the molecular weight distribution of the obtained resin was measured by gel permeation chromatography, it had one peak at a molecular weight of 3.5 million.

<Styrene-Acrylic 2 to 4 (B-2 to
4) and Synthesis of Comparative Styrene-Acrylic 1 (B-5)>
Similar to Styrene-Acrylic 1, Styrene-Acrylic 2-4 (B-2-4), Comparative Styrene-Acrylic 1 (B
-5) was synthesized. Table 2 shows the monomer composition and the peak molecular weight measured by gel permeation chromatography.

<Synthesis of Comparative Styrene-Acrylic 2 (B-6)> 68 parts by weight of styrene monomer, 28 parts by weight of butyl acrylate monomer, 4 parts by weight of methacrylic acid monomer, 0.3 parts by weight of polyvinyl alcohol, degassed water 200 Parts by weight and 0.15 parts by weight of benzoyl peroxide are mixed and suspended, and the suspension dispersion is heated and reacted at a temperature of 78 ° C. for 20 hours under a nitrogen atmosphere to carry out suspension polymerization. -6) was obtained.

When the molecular weight distribution of the obtained resin was measured by gel permeation chromatography, it had one peak at a molecular weight of 1.5 million.

<Synthesis of Comparative Styrene-Acrylic 3 (B-7)> 74.5 parts by weight of styrene monomer, 21 parts by weight of butyl acrylate monomer, 0.5 parts by weight of divinylbenzene, 4 parts by weight of acrylic acid monomer, 0.3 parts of polyvinyl alcohol.
Parts by weight, 200 parts by weight of degassed water and 0.05 parts by weight of benzoyl peroxide are mixed and suspended, and the suspension is heated and reacted under a nitrogen atmosphere at a temperature of 78 ° C. for 40 hours to carry out suspension polymerization. Then, a comparative styrene-acrylic 3 (B-7) was obtained.

When the molecular weight distribution of the obtained resin was measured by gel permeation chromatography, it had one peak at a molecular weight of 5.5 million.

[0067]

[Table 2]

(Production of Toner) <Production of Toner 1> 60 parts by weight of Resin A-1, Resin B-2
40 parts by weight and 100 parts by weight of toluene were added to a three-necked flask equipped with a falling condenser, a steel stirrer, and a thermometer, and the mixture was stirred for 1 hour while maintaining the temperature at 120 ° C.
100 parts by weight of the blended resin that had been cooled and desolvated and then pulverized, 5 parts by weight of low molecular weight polypropylene wax, and 10 parts by weight of carbon black were dry blended in a V-type mixer. This mixture was hot melt kneaded, cooled, and then made to have a volume average particle diameter of 8.5 μm by a jet mill. The obtained crushed toner 10
0 parts by weight, positively chargeable external additive 1: 1.0 part by weight, and zinc stearate 0.1 part by weight were dry blended by a turbula to obtain a positively chargeable toner 1.

<Production of Toners 2 to 9> In the same manner as Toner 1, positively chargeable toners (Toners 2 to 9) were obtained. In Table 3,
Polyester component used, styrene-acrylic component,
The mixing ratio wax formulation and external additive formulation are shown.

[0070]

[Table 3]

<Production of Toner 10> Resins A-1 and B-2
Each of them was made to have a particle diameter of 15 μm by a jet mill. 80 parts by weight of the obtained resin A-1 pulverized product, 20 parts by weight of resin B-2 pulverized product, 5 parts by weight of low molecular weight polypropylene wax, and 10 parts by weight of carbon black were dry blended for 30 minutes in a Henschel mixer. This mixture was melt-kneaded by heat, cooled, and then made to have a volume average particle diameter of 8.5 μm by a jet mill. 100 parts by weight of the obtained pulverized completed toner, 1: 1.0 part by weight of the positively chargeable external additive, and 0.1 part by weight of zinc stearate were dry blended with a turbuler to obtain a positively chargeable toner.

<Production of Toner 11> Toner 11 was produced in the same manner as Toner 10. Table 3 shows the polyester component, styrene-acrylic component, wax formulation, and external additive formulation used.

<Production of Comparative Toners 1 to 14> Comparative Toners 1 to 14 were produced in the same manner as Toner 1. Table 1 shows the used polyester component, styrene-acrylic component, their mixing ratio wax formulation, and external additive formulation.

Incidentally, Comparative Toner 11 was not able to obtain a predetermined volume average particle diameter (8.5 μm) because the pulverizability was significantly deteriorated.

[0075]

[Table 4]

<Preparation of two-component developer> Volume average particle size 80 μ
95 parts by weight of m ferrite carrier and the toners 1 to 11 and comparative toners 1 to 14 were dry blended to prepare a two-component developer. Note that the comparative toner 14 could not be used for the real image evaluation because the charge amount was too low.

(Evaluation) Toners 1 to 11, Comparative Toners 1 to 14
Was evaluated as follows. The evaluation results are listed in Tables 5 and 6.

(1) Dispersion A toner kneading plate stretched by a cooling roller after kneading is
An ultrathin section of 15 nm was made perpendicular to the ejection direction of the toner kneaded material. This ultrathin section was observed with a transmission electron microscope to determine the dispersion state of the polyester component and the styrene-acrylic component.

The evaluation is “◯” when the styrene-acrylic component forms microdomains having a dispersion diameter of 0.3 μm or less with respect to the polyester component, “x” when the dispersion diameter exceeds 0.3 μm, and “s” when the styrene-acrylic component is When it existed in a "river" shape, it was designated as "XX".

(2) Positive charging property 1 g of toner, ferrite carrier 1 having a volume average particle size of 80 μm
9 g was weighed into a 20 ml sample tube, the toner and carrier were shaken in the sample tube for 20 minutes, and the toner charge amount was measured by a blow-off type charge amount measuring device.

Further, in order to confirm the charging uniformity of the toner, it was measured by "Espart Analyzer" manufactured by Hosokawa Micron Co., Ltd. whether or not there is a weakly charged toner of +5 μC / g or less.

(3) Attrition resistance As a copying machine for evaluation, a copying machine modified for toner recycling was used for actual copying using a modified Konica 3035 machine manufactured by Konica Corporation, and the developer was sampled at 10,000 copies. The toner fine powder amount (number%) in the toner was measured using "Coulter Counter TA-II" manufactured by Coulter.

(4) External additive dislodge As a copying machine for evaluation, "Konica 3035" manufactured by Konica Corporation, which was modified for toner recycling, was used for actual copying to obtain 10,0
The toner present in the recycle pipe at 00 copy was collected. The surface of the recycled toner was analyzed by "ESCA1000" manufactured by Shimadzu Corporation, and the reduction rate of the toner surface amount of the positively chargeable external additive with respect to the toner not used for copying (unused toner) was measured. As an evaluation,
Binder resin component, wax, carbon-C1s due to colorant, oxygen-O1s, nitrogen-N1s and silicon-Si2p due to positively chargeable external additive, aluminum-Al2p peaks are detected and caused by external additive. Change in the peak intensity of silicon-Si2p and aluminum-Al2p (percentage of the total peak area; atomic number%), that is, Si2p of the unused toner
Or, for recycled Al2p peak intensity,
Si2p or Al2p peak intensity was calculated as a percentage and Si-
Al residual rate (%) was used.

(4) Toner Spent As an evaluation copying machine, "Konica 3035" manufactured by Konica Corporation, which was modified for toner recycling, was used for actual copying to obtain 10,0
The developer at 00 copies was sampled and washed with neutral detergent to remove the toner. 4 g of the obtained carrier was washed with 200 ml of 2-butanone, the washing was collected in a 200 ml measuring flask, shaken well, and then treated with an ultrasonic vibration device for 10 minutes. The transmittance of this solution was measured by Hitachi's "Autograph U-3500 type spectrophotometer"
It was measured with the transmittance of butanone alone as 100%.

(5) As a copying machine for fogging evaluation, a Konica 3035 manufactured by Konica Corporation, which was modified for toner recycling, was used for actual copying, and a "Sakura densitometer" manufactured by Konica Corporation was used. , 10,000
The copied image in the copy was measured as the relative density of the white background.

(6) As a copying machine for evaluating toner scattering, a Konica 3035 manufactured by Konica Corporation, which was modified for toner recycling, was used for actual copying, and a "Sakura Densitometer" manufactured by Konica Corporation was used. Used, 10,000
The state of toner scattering in the copying machine during copying was visually determined. The evaluation was "O" when no toner scattering was observed, "X" when toner scattering was recognized, and "XX" when toner scattering was considerably large.

[0087]

[Table 5]

[0088]

[Table 6]

As can be understood from the results of the above examples, according to the present invention, toner fine particles are less likely to be generated without being ground in the developing machine, and the positively chargeable external additive is less likely to be electrostatically removed. As a result, it is possible to provide a positively chargeable toner that does not cause fogging and toner scattering even during long-term copying.

[0090]

According to the present invention, the chargeability between toner particles is uniform, there is no weakly charged toner, the external additive does not come off before and after toner recycling, and the toner is not ground in the developing machine.
It is possible to provide a toner that does not generate toner spent due to generation of fine powder and can be optimally used in an electrophotographic copying machine having a toner recycling mechanism.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a toner recycling system used in the present invention.

FIG. 2 is a diagram illustrating a toner recycling system used in the present invention.

[Explanation of symbols]

 1 Developing Device 3 Photoconductor 4 Cleaning Device 6 Toner Conveying Screw 1 7 Toner Conveying Screw 2 9 Toner Supply Box

Claims (2)

[Claims] 1. A positively chargeable developing toner used in an electrophotographic copying machine having a toner recycling mechanism, wherein the toner comprises at least a binder resin component, a colorant and a positively chargeable external additive, and the binder resin component is Polyester component 60 to 90% by weight and styrene-acrylic component 40 to 10% by weight. In the polyester component, hydroxyl value (OHV) is 10 to 50, acid value (AV) is 10 to 50, and hydroxyl value and acid value are OHV / AV is 0.5 or more and less than 2.0,
The weight average molecular weight in the molecular weight distribution measured by gel permeation chromatography is 20,000-
80,000, the styrene-acrylic component has a carboxyl group in the polymer side chain, and in the molecular weight distribution measured by gel permeation chromatography, at least one peak or shoulder is present in the molecular weight range of 2 to 5 million. A positively chargeable developing toner characterized by having three. 2. The positively chargeable developing toner according to claim 1, wherein the positively chargeable developing toner contains a positively chargeable external additive having a number average primary particle diameter of 0.01 to 0.3 μm.