JPH04225367A - Nonmagnetic one component developing method - Google Patents

Abstract

PURPOSE:To exhibit high printing quality and prevent the occurrence of image change even when continuously printing in the nonmagnetic one component developing method used to such as an electrophotographic copying machine or electrophotographic printer. CONSTITUTION:Stylene-acryl-butadien, polyester or urethane modified polyester resin is used as the binder resin of the developer and is mixed with 0.3-3wt.% particulates having >=100m<2>/g BET specific surface area to the developer.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nonmagnetic one-component developing method used in electrophotographic copying machines, electrophotographic printers, and the like.

0002

[Prior Art] Conventionally, in electrophotographic copying machines and electrophotographic printers, the surface of a uniformly charged photoreceptor is generally exposed to light according to image information using a laser or the like to form an electrostatic latent image. Thereafter, the charged developer is conveyed by the developer carrier to the contact portion with the photoreceptor and is attached thereto by electric force, thereby converting the electrostatic latent image into a visible image, that is, developing it. After the visible image of this toner is transferred onto recording paper using electrical force, it is fixed using heat, pressure, light, etc. to obtain copies or prints.

Conventionally, in a one-component type developer, the amount of developer deposited on the developer carrier 3 is regulated using a layer thickness regulating member 6 as shown in FIG. Acrylic or polyester resin was used.

0004

However, as shown in FIG. 2, in the conventional non-magnetic one-component developing method, since the layer thickness regulating member 6, which imparts a charge as a developer, and the developer are strongly triboelectrically charged, The toner 1 is worn out, causing toner fusion 15 on the layer thickness regulating member 6. For this reason, with continuous printing,
The amount of this fusion increases in some parts, and there are parts on the layer thickness regulating member 6 where the toner 1 is difficult to be charged, resulting in uneven printing on the image (
There was a problem in that ``black streaks'' and ``white streaks'' were produced.

An object of the present invention is to provide a non-magnetic one-component developing method that provides high print quality and does not cause image changes even when continuous printing is performed.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a method for triboelectrically charging a developer conveyed by a developer carrier to a latent image carrier using a layer thickness regulating member, and In a non-magnetic one-component development method in which development is carried out by regulating 0.3 to 3% by weight of fine particles with a particle size of 100 m2/g or more are mixed.

Continuous printing can be achieved by using tough styrene-acrylic-butadiene, polyester, or urethane-modified polyester as the toner binder resin, and by externally adding fine particles that act as a cushion between the toner and the layer thickness regulating member. The accompanying fusion of toner to the layer thickness regulating member is eliminated. On the other hand, styrene is commonly used as a binder resin for toner.
When using acrylic resin, even if fine particles are externally added, the resin is soft and will be finely pulverized when it rubs against the layer thickness regulating member, making it unsuitable for continuous printing. Furthermore, even when a stronger styrene-acrylic-butadiene, polyester, or urethane-modified polyester toner is used as a toner, if fine particles are not externally added or the amount is 0.3% by weight or less,
Because there is a high percentage of direct contact between the toner and the layer thickness regulating member,
Printing unevenness is likely to occur. Furthermore, if 3% by weight or more is externally added, the external additive will scatter during continuous printing, reducing print quality. Further, when the BET specific surface area is 100 m2/g or less, the particles are large and tend to be non-uniform on the toner, resulting in less effect.

The binder resin for styrene-acrylic-butadiene toner that can be used herein refers to a resin obtained by radical polymerization of styrene monomer, acrylic monomer and butadiene monomer. Styrene monomers and acrylic monomers include styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, chlorostyrene, bromostyrene, dichlorostyrene, dibromo styrene, p-phenylstyrene, te
rt-butylstyrene, methyl methacrylate, n-
Butyl methacrylate, n-octyl methacrylate,
Methyl acrylate, divinylbenzene, diallyl phthalate, maleic acid, maleic acid half ester, acrylonitrile, ethylene glycol dimethacrylate,
Examples include ethylene glycol diacrylate and trimethylolpropane trimethacrylate. Examples of butadiene monomers include 1,3-butadiene, chloroprene, and isobutylene.

[0009] As the binder resin for polyester toner, any ordinary commercially available resin may be used, and either a crosslinked polyester resin or a non-crosslinked resin may be used. Alcohol components of polyester include ethylene oxide of bisphenol A, ethylene glycol, propylene glycol, neopentyl glycol, etc., and acid components include phthalic acid, succinic acid, isophthalic acid, trimellitic acid, maleic acid, etc. obtained by condensation polymerization. Refers to resin that has been

[0010] There are also the following two methods for obtaining urethane-modified polyester toner. 1. A method of urethane modification by reacting a hydroxyl group which is a reactive residue in a general-purpose crosslinked polyester resin having a hydroxyl value of 1 mgKOH/g or more (JP-A-62-295068, JP-A-02-989) with a monofunctional isocyanate. Specifically, the crosslinked polyester resin other than the gel portion is dissolved in trichlene or the like and reacted with a monofunctional isocyanate. The crosslinked polyester resin having a hydroxyl value of 1 mgKOH/g or more used herein is one obtained by condensing a divalent or trivalent or higher polyhydric alcohol with a difunctional or trivalent or higher polyfunctional acid component.

2. A polyester in the form of an oligomer is produced by containing several percent of a trifunctional or higher polyfunctional alcohol component in advance, and the hydroxyl group, which is the reaction residue, is reacted with a bifunctional isocyanate to elongate the polyester, resulting in a cross-linked urethane-modified polyester resin. There is a method to
49768, 63-56659, JP 1-15406
8 Publication).

In either case, toughness is improved compared to general-purpose polyester resins. Examples of bifunctional alcohol components that can be used as monomers for producing polyester that can be used here include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, and 1,2-propylene glycol.
-butanediol, 1,3-butanediol, 1,4-
Examples include butanediol, neopentyl glycol, diethylene glycol, an ethylene oxide adduct of bisphenol A, and a propylene oxide adduct of bisphenol A.

Examples of the trifunctional or higher polyfunctional alcohol component include glycerin, trimethylolpropane, trimethylolethane, pentaerythritol, and the like. Bifunctional acid components include malonic acid, succinic acid, azelaic acid,
maleic acid, fumaric acid, itaconic acid, citraconic acid,
Examples include phthalic acid and isophthalic acid. Examples of the trifunctional or higher polyfunctional acid component include trimellitic acid and naphthalenetricarboxylic acid.

[0014] As the monofunctional isocyanate, parabromophenyl isocyanate, n-butyl isocyanate,
tert-butyl isocyanate, tert-butyl isocyanate acetate, β-chloroethyl isocyanate, m-chlorophenylisocyanate, o-chlorophenylisocyanate, p-chlorophenylisocyanate, chlorosulfonyl isocyanate, cyclohexyl isocyanate, 2,5-dichlorophenylisocyanate, 3, 4-Dichlorophenyl isocyanate, ethyl isocyanate, ethyl isocyanate acetate, o-fluorophenyl isocyanate, p-
Fluorophenyl isocyanate, isopropylisocyanate, (R)-(+)-α-methylbenzyl isocyanate, (s)-(-)-α-methylbenzyl isocyanate, (R)-(+)-1-(1-naphthyl) Ethyl isocyanate, (s)-(-)-1-(1-naphthyl)ethyl isocyanate, α-naphthyl isocyanate, m-nitropropylisocyanate, p-nitropropylisocyanate, n-octadecyl isocyanate, phenyl isocyanate, n-propylisocyanate , p-toluenesulfonyl isisoanate, m
-tolyl isocyanate, p-tolyl isocyanate,
Examples include trichloroacetyl isocyanate, trifluoromethylphenyl isocyanate, trimethylsilyl isocyanate, and the like.

[0015] As the difunctional isocyanate, 3,3'
-dichlorophenyl-4,4'-diisocyanate, 4
, 4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 1,5-naphthylene diisocyanate, 2,2'
, 5,5'-tetrachlorodiphenyl 4,4' diisocyanate, toluene diisocyanate, toluene 2,4
-diisocyanate, toluene 2,6-diisocyanate, trimethylhexamethylene diisocyanate, m-
Examples include xylene diisocyanate and tolylene diisocyanate.

Furthermore, the BET specific surface area is 100 m2 /g
Examples of the above-mentioned fine particles include hydrophobic silica, titanium oxide, and alumina. As a commercially available hydrophobic silica, R
972D (Japan Aerosil, BET specific surface area: 110m
2 /g), R805 (Nippon Aerosil, BET specific surface area: 150m2 /g), R974 (Nippon Aerosil, BET specific surface area: 170m2 /g), F1
00 (Toray Silicone, BET specific surface area: 140m2
/g), F101 (Toray Silicone, BET specific surface area: 190 m2 /g), N-70TS (Cabot, BET specific surface area: 100 m2 /g), TS-
530 (Cabot, BET specific surface area: 200m2
/g), H-2000 (Hoechst, BET specific surface area: 140m2 /g), H30D (Hoechst, BE
T specific surface area: 250 m2 /g), for titanium oxide,
SST95S (Titan Kogyo, BET specific surface area: 100
m2 /g), for alumina, ALMINIUM O
XIDE C (Japan Aerosil, BET specific surface area: 10
0m2/g) etc.

Next, a non-magnetic one-component developing method will be explained using the apparatus shown in FIG. In FIG. 1, a movable agent is coated on the surface between a storage means 2 that stores the developer 1 and a developer carrier 3 that transports the developer 1 along a predetermined circulation path including the development area. The developer collecting means 4 in the form of a roller is provided so as to be in contact with the developer carrier 3, and between the developer carrier 3 and the developer collecting means 4, the developer 1 is removed from the developer carrier 3. A bias voltage (hereinafter referred to as recovery bias) is applied in the direction from the developer recovery means 4 to the developer recovery means 4, and stable and reliable development is achieved by not only mechanical recovery by contact but also electrical cancellation by the recovery bias. Mechanical and electrical history on the agent carrier 3 is eliminated. So, a new
The developer 1 stored in the storage means 2 while in contact with the developer carrier 3 is supplied to the developer carrier 3 by the developer supply means 5, and the developer is removed by mechanical friction by the layer thickness regulating member 6. It is charged to form a charged toner layer on the developer carrier 3, and after regulating the layer thickness to a desired thickness, it is transported to a developing area and developed.

Reference numeral 7 denotes a latent image carrier, which conveys the latent image formed on its surface to a developing section, and conveys the formed image of the developer 1 to a position where it is transferred onto the recording paper 14. As the latent image carrier 7, a photoconductive material such as an insulator (organic photoconductor, selenium photoconductor, amorphous silicon photoconductor, etc.), which is a photoconductive material, can be used depending on the latent image forming method. In the figure, 8 is an exposure device, 9 is a pre-charger, 10 is a cleaner unit, 11 is a static elimination lamp, 12 is a fixing device, and 13 is a transfer device.

The developer carrier 3 used here is made of porous polyurethane with pores of 3 to 20 μm.
Toner with a diameter of around 0 μm was prevented from entering. It was confirmed that even when the porous state is in a continuous open cell state, when the size of the pores is set to 20 μm or less, the toner supports each other within the pores and does not invade. Also, 20μ
If the pores are larger than m, it is possible to prevent toner from entering by using a single cell, but the distance between the latent image and the conductor (in this case, the sponge itself) becomes large in the recessed part, and the toner in that part is subject to development bias. The print will no longer be coated, and a low-density area corresponding to the concave portion of the sponge will appear on the print. Therefore, the pore area is 20
A size of μm or less is desirable. The volume resistivity value of the sponge is preferably in the range of 104 to 1010 Ωcm.If the electrical resistance value is high, the potential difference between the surface of the carrier and the surface of the latent image carrier will be large, causing background fog, and if the electrical resistance value is low, the layer A large current flows into the thickness regulating member 6, generating Joule heat, and the developer carrier 3 is burnt out. Further, the surface hardness of the developer carrier was 50° or less using an Asker C hardness meter.

[0020]

EXAMPLES The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited thereto. Example 1 90 parts by weight of styrene-acrylic-butadiene resin (styrene:butyl acrylate:1,3-butadiene=8:2:1) was used as a binder resin, and carbon black (Black Pearls L; average particle size: 2.0 parts by weight) was used as a coloring agent. 3μ
m, specific surface area 138 m2/g; Cabot Corporation) 5 parts by weight, azo dye (Bontron S-34 Orient Chemical) 1 part by weight, propylene wax (Viscol)
550P (manufactured by Sanyo Chemical) was added thereto, and melt-kneaded at 160° C. for 30 minutes using a pressure kneader to obtain a toner mass. The cooled toner mass was reduced to approximately 2 mm coarse toner using a rotoplex mill. Next, the coarse toner was pulverized using a jet mill (PJM pulverizer, manufactured by Nippon Pneumatic Industries), and the pulverized product was classified using an air classifier (manufactured by Alpine) to form toner A with a particle size of 5 to 20 μm. Obtained. Titanium oxide, SST9 based on 100% by weight of toner A
5S (Titan Kogyo, BET specific surface area: 100m2 /g
)0.3% by weight was mixed in a Henschel mixer. Loading 200g of this toner into the device (20 sheets/min), a continuous printing test was conducted to examine the printing quality, presence or absence of filming on the layer thickness regulating member, and changes in the particle size distribution of the toner on the developer carrier. Ta.

[0021] As a result, even after 100,000 sheets of continuous printing, the print quality
The particle size distribution of the toner did not change at all. Furthermore, there was no problem with the filming of the triboelectric charging member, and no white streaks or black streaks appeared on the prints or images. Example 2 In Example 1, titanium oxide and SST were used for toner A.
95S (Titan Kogyo, BET specific surface area: 100m2 /
g), hydrophobic silica R972D (Nippon Aerosil, BET specific surface area: 110 m2 /g) was added,
A similar experiment was conducted.

[0022] As a result, even after 100,000 sheets of continuous printing, the print quality
The particle size distribution of the toner did not change at all. Furthermore, there was no problem with the filming of the triboelectric charging member, and no white streaks or black streaks appeared on the prints or images. Example 3 In Example 1, titanium oxide and SST were used for toner A.
95S (Titan Kogyo, BET specific surface area: 100m2 /
g) instead of alumina ALMINUM OXID
E C (Japan Aerosil, BET specific surface area: 100m2
/g) and the same experiment was conducted.

[0023] As a result, even after 100,000 sheets of continuous printing, the print quality
The particle size distribution of the toner did not change at all. Furthermore, there was no problem with the filming of the triboelectric charging member, and no white streaks or black streaks appeared on the prints or images. Example 4 General-purpose polyester resin (ER-101,
Toner B was produced in the same manner as in Example 1 using Hydrophobic Silica H30D (Hoechst, BET).
Specific surface area: 250 m2 /g) 0.3% by weight of toner B
Using this toner, the above device (20 sheets/min)
A continuous printing test was conducted to examine the printing quality, the presence or absence of filming on the layer thickness regulating member, and changes in the particle size distribution of the toner on the developer carrier.

[0024] As a result, even after 100,000 sheets of continuous printing, the print quality
The particle size distribution of the toner did not change at all. Furthermore, there was no problem with the filming of the triboelectric charging member, and no white streaks or black streaks appeared on the prints or images. Example 5 In Example 1, titanium oxide and SST were used for toner A.
95S (Titan Kogyo, BET specific surface area: 100m2 /
g), hydrophobic silica R972D (Nippon Aerosil, BET specific surface area: 110 m2 /g) was added,
A similar experiment was conducted.

[0025] As a result, even after 100,000 sheets of continuous printing, the print quality
The particle size distribution of the toner did not change at all. Furthermore, there was no problem with the filming of the triboelectric charging member, and no white streaks or black streaks appeared on the prints or images. Example 6 In Example 1, titanium oxide and SST were used for toner A.
95S (Titan Kogyo, BET specific surface area: 100m2 /
g) instead of alumina ALMINUM OXID
E C (Japan Aerosil, BET specific surface area: 100m2
/g) and the same experiment was conducted.

[0026] As a result, even after 100,000 sheets of continuous printing, the print quality
The particle size distribution of the toner did not change at all. Furthermore, there was no problem with the filming of the triboelectric charging member, and no white streaks or black streaks appeared on the prints or images. Example 7 General-purpose polyester resin (ER-101,
Mitsubishi Rayon) and hexamethylene diisocyanate were reacted and a urethane-modified polyester resin was used to produce toner C in the same manner as in Example 1.
INIUMOXIDE C (Japan Aerosil, BET
Specific surface area: 100m2/g) toner C0.3% by weight
Using this toner, the above device (20 sheets/min)
A continuous printing test was conducted to examine the printing quality, the presence or absence of filming on the layer thickness regulating member, and changes in the particle size distribution of the toner on the developer carrier.

[0027] As a result, even after 100,000 sheets of continuous printing, the print quality
The particle size distribution of the toner did not change at all. Furthermore, there was no problem with the filming of the triboelectric charging member, and no white streaks or black streaks appeared on the prints or images. Example 8 Ethylene glycol, succinic acid and trimethylolpropane were placed in a 10 L flask and reacted at 200°C to obtain a polyester oligomer with an average molecular weight Mw of 2000. A xylene solution was poured into this polyester oligomer to obtain a xylene solution of polyester oligomer. To 100 parts by weight of this polyester oligomer, 3 parts by weight of xylylene diisocyanate was added to simplify the reaction, and then the xylene was distilled off. Oxidation = 10
, 11% by weight of ethyl acetate insoluble matter) was obtained.

Toner D was produced in the same manner as in Example 1 using a cross-linked urethane-modified polyester resin, and hydrophobic silica H30D (Hoechst, BET specific surface area: 250 m2
/g) 0.3% by weight was externally added to D, and using this toner, it was installed in the above device (20 sheets/min) and a continuous printing test was conducted to check the printing quality and the presence or absence of filming of the layer thickness regulating member. And changes in the particle size distribution of the toner on the developer carrier were investigated.

[0029] As a result, even after 100,000 sheets of continuous printing, the print quality
The particle size distribution of the toner did not change at all. Furthermore, there was no problem with the filming of the triboelectric charging member, and no white streaks or black streaks appeared on the prints or images. Examples 9 to 16 The BET specific surface area of each of Examples 1 to 8 is 100 m2
The same evaluation was performed with the amount of fine particles added of /g or more being 3% by weight.

[0030] As a result, even after 100,000 sheets of continuous printing, the print quality
The particle size distribution of the toner did not change at all. Furthermore, there was no problem with the filming of the triboelectric charging member, and no white streaks or black streaks appeared on the prints or images. Comparative Examples 1-8 Each BET specific surface area of Examples 1-8 is 100 m2
The same evaluation was performed with the amount of fine particles added of /g or more being 0.1% by weight.

[0031] As a result, in all samples, 2000~
Continuous printing of about 5,000 sheets caused filming due to fusion on the frictional charging member, and white streaks and black streaks appeared in the print. Further, the amount of fine powder toner (toner of 5 μm or less) was less than 1% at the initial stage, but it increased to more than 5% after 10,000 sheets were printed. Comparative Examples 9 to 16 BET specific surface area of each of Examples 1 to 8 is 100 m2
The same evaluation was performed with the amount of fine particles added of /g or more being 5% by weight.

As a result, there was a lot of scattering of hydrophobic silica from the beginning, resulting in poor print quality. Comparative Example 17 Toner D was produced in the same manner as in Example 1 using a general-purpose styrene-acrylic resin (TB1000, Sanyo Chemical) as a binder,
For 100% by weight of this toner, hydrophobic silica H30
D (Hoechst, BET specific surface area: 250 m2 /g) 1
% by weight, and using this toner, the above device (20 sheets/
A continuous printing test was conducted to examine the printing quality, presence or absence of filming on the layer thickness regulating member, and changes in the particle size distribution of the toner on the developer carrier.

[0033] As a result, by continuous printing of about 2000 sheets,
Filming occurred due to fusion on the frictional charging member, and white streaks and black streaks appeared in the print. Also, the initial fine powder toner (
The amount of toner (with a diameter of 5 μm or less) was less than 1%, but it increased to more than 5% after 10,000 sheets were printed.

[0034]

As explained above, according to the present invention, styrene-acrylic-
By using butadiene, polyester, or urethane-modified polyester and mixing 0.5 to 3% by weight of fine particles with a BET specific surface area of 100 m2 /g or more to the toner, printing quality can be maintained even during continuous printing. is high, and screen changes do not occur.

[Brief explanation of the drawing]

[Figure 1] Diagram showing an electrophotographic recording device

[Figure 2] Explanatory diagram explaining conventional problems

[Explanation of symbols]

1: Developer
2: Storage means 3: Developer carrier
4: Developer recovery means 5: Developer supply means
6: Layer thickness regulating member 7: Latent image carrier
8: Exposure device 9: Pre-charger
10: Cleaner unit

Claims (1)

[Claims] 1. A non-magnetic one-component developing method in which a developer conveyed by a developer carrier to a latent image carrier is triboelectrically charged by a layer thickness regulating member and development is carried out by regulating the layer thickness. As the binder resin of the developer, styrene-acrylic-butadiene, polyester, or
A non-magnetic one-component developing method using urethane-modified polyester and comprising mixing 0.3 to 3% by weight of fine particles having a BET specific surface area of 100 m2/g or more with respect to the developer.