JPH083649B2 - Electrostatic latent image developer - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an electrostatic latent image developer used for developing an electrostatic latent image.

2. Description of the Related Art Development of an electrostatic latent image electrostatically attracts negatively or positively triboelectrically charged toner to an electrostatic latent image having a positive or negative charge formed on a photoconductor by various methods. Then, transfer the toner image onto the transfer paper,
The fixed image fixes the developed image.

At that time, it is known to add fine powder of silica, titanium oxide or the like in order to impart fluidity and good chargeability to the toner and to enhance transfer efficiency (this fine powder is generally used as a fluidizing agent. I call it). When the fine powder is used by adding it to the toner without any treatment, the toner does not have a sufficient charge, and the developing efficiency tends to be poor, and toner scattering and image blurring tend to occur. It was remarkable when wet.

Therefore, for the purpose of eliminating the above drawbacks, a technique has been proposed in which a fluidizing agent is subjected to a hydrophobic treatment with an aluminum-based coupling agent (JP-A-60-140360). However, this product has weak hydrolysis resistance, and the toner charge amount is reduced by long-term storage, and this tendency is large especially under high temperature and high humidity, and fog or the like occurs in image quality.

Further, a fluidizing agent which has been hydrophobized with a silane coupling agent has also been proposed (JP-A-59-34539). With this type, as the copying is repeated, the charge amount of the toner rises extremely, and between the toner and the toner carrier,
Alternatively, the two-component developer has a drawback that electrostatic attraction between the toner and the carrier is increased, the amount of the toner moving to the photoconductor is reduced, and the image density is lowered.

Problems to be Solved by the Invention In a conventional toner to which a fluidizing agent subjected to a hydrophobic treatment is added, the toner charge amount decreases at high humidity, and the toner charge amount becomes unstable with repeated copying. There is a drawback that the image density decreases.

The present inventors have found that the above problems can be solved by hydrophobizing the fluidizing agent with a zirco aluminum-based coupling agent that has not been used conventionally.
Succeeded in obtaining a fluidizing agent for an electrostatic latent image developer that maintains a proper amount of charge even after being left in high humidity for a long period of time and can obtain a clear image without fog even when repeatedly copying. did.

Means for Solving the Problems That is, an electrostatic latent image obtained by externally adding titanium oxide or aluminum oxide hydrophobized with a zirco aluminum-based coupling agent to a toner containing at least a thermoplastic resin and a colorant. Regarding the developer.

As the fluidizing agent that can be used in the present invention, titanium oxide,
Examples thereof include aluminum oxide, silica / titanium oxide mixture, and silica / aluminum oxide mixture.

In the present invention, the above fluidizing agent is used after being hydrophobized with a zirco aluminum-based coupling agent.

Zirco aluminum coupling agent [In the formula, X and Y may be the same or different and each represents an amino group, a carboxyl group, a mercapto group, a carboxyl group-containing higher alkyl group or a methacryloxy group, and n is a number of 1 or more] A compound represented by the following formula, which is sold under the following trade names, can be obtained.

Cabco Mod A, Cabco Mod C, Cabco Mod S, Cabco Mod FPN, Cabco Mod MPG, Cabco Mod C-1, Cabco Mod F, Cabco Mod M, Cabco Mod M -1, Cabco Mod APG, Cabco Mod CPG, Cabco Mod CP
M, Cabco Mod MPM (both of which are manufactured by Cabedon Chemical).

All of the above zirco aluminum-based coupling agents can be used.

The amount of the zirco aluminum-based coupling agent used is 0.1 wt% to 30 wt%, preferably 1 wt% based on the amount of the fluidizing agent.
Used in the range of 20% to 20% by weight. If it is less than 0.1 wt%, the desired effect of the present invention cannot be sufficiently obtained, and if it exceeds 30 wt%, the fluidity is lowered.

The zirco aluminum-based coupling agent may be used in combination with another coupling agent such as a silane-based coupling agent, a titanium-based coupling agent or an aluminum-based coupling agent.

The fluidizing agent hydrophobized with a zirco aluminum-based coupling agent is added to the toner in which the thermoplastic resin and the colorant are dispersed, and it is used by externally adding it to the toner. In addition to these, the toner may contain a chromium-containing oil-soluble dye, a nigrosine-based oil-soluble dye, and the like as a charge control agent, if necessary.

The fluidizing agent hydrophobized with a zirco aluminum-based coupling agent is used by adding to the toner in an amount of 0.1 wt% to 1 wt%, preferably 0.1 wt% to 0.5 wt%. If it is 0.1 wt%, the desired effect of the present invention cannot be sufficiently obtained, and if it exceeds 1 wt%, the fluidity becomes unnecessarily high and the toner scattering becomes large.

Examples of the thermoplastic resin include homopolymers of styrene such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene and substitution products thereof, styrene-p-chlorostyrene copolymers, styrene-propylene copolymers, styrene-
Vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, Styrene-methyl methacrylate copolymer, styrene- (methacrylic acid) ethyl copolymer, styrene-butyl methacrylate copolymer, styrene-d methyl chloromethacrylate copolymer, styrene-acrylonitrile copolymer, styrene- Vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene- Maleic acid copolymer, styrene Down - styrene copolymer and maleic acid ester copolymer, polymethyl methacrylate,
Polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, polyurethane, polyamide, epoxy resin, polyvinyl butyral, polyamide, polyacrylic acid resin,
Rosin, modified rosin, terpene resin, phenolic resin,
Aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, paraffin wax and the like can be used alone or in combination.

Further, in order to use the toner of the present invention as a magnetic toner, magnetic powder may be contained. As such magnetic powder, a substance that is magnetized when placed in a magnetic field is used.
There are powders of ferromagnetic metals such as iron, cobalt and nickel, or alloys and compounds such as magnetite, hematite and ferrite.

The content of this magnetic powder is 15 ~ 70wt% to the toner weight.
It is preferred that

[Synthesis Example 1] 5 g of a zirco aluminum-based coupling agent, CAVCO MODA (manufactured by CAVEDON CHEMICAL), was mixed with 250 ml of ethyl alcohol, and TK homogenizer (manufactured by Tokushu Koki Co., Ltd.). Stir for about 10 minutes to disperse evenly.

There, hydrophilic titanium dioxide (Aerosil P-25)
Add 100 g of fine powder (made by Degussa) and slowly add about 1
Stir for hours. After that, pass through a decompressor, 50-60 ℃
After drying with hot air for 3 hours and vacuum drying at 50-60 ° C. for 5 hours, it is dispersed with a TK homogenizer at 2000 rpm for 5 minutes to obtain hydrophobized titanium oxide fine powder (average particle size 30 mμm) as a fluidizing agent according to the present invention.

[Synthesis Example 2] 20 g of a zirco aluminum-based coupling agent, Cabco Mod C (Cabdon.
(Manufactured by Chemical Co., Ltd.) and mixed with a TK homogenizer for about 10 minutes to uniformly disperse.

Then, 100 g of fine powder of hydrophilic silica (Aerosil 300) (manufactured by Nippon Aerosil Co., Ltd.) is added, and the mixture is slowly stirred for 1 hour.

Then, the mixture was passed through a decompressor, dried with hot air at 50-60 ° C for 3 hours, then vacuum dried at 50-60 ° C for 5 hours, and then dispersed with a homogenizer at 2000 rpm for 5 minutes to give a hydrophobicity as a fluidizing agent according to the present invention. A fine silica powder (average particle size 7 mμm) is obtained.

[Synthesis Example 3] 7 g of a zirco aluminum-based coupling agent Cabco Mod S (manufactured by Cabdon Chemical Co.) was mixed in a mixed solvent of 200 ml of methanol and 50 ml of water, and a TK homogenizer was used.
Stir for 10 minutes to evenly disperse.

100 g of fine powder of hydrophilic aluminum oxide C (manufactured by Nippon Aerosil Co., Ltd.) is put therein and stirred slowly for 1 hour.

Then, the mixture was passed through a decompressor, dried with hot air at 50 to 60 ° C for 3 hours and then vacuum dried at 50 to 60 ° C for 5 hours, and then stirred with a homogenizer at 2000 rpm for 5 minutes to obtain a fluidizing agent according to the present invention. A hydrophobic aluminum oxide fine powder (average particle size 7 mμm) is obtained.

[Synthesis Example 4] 300 g of n-hexane was mixed with 10 g of a zirco aluminum-based coupling agent, Cabco Mod FPM (manufactured by Cabdon Chemical Co.), and the mixture was uniformly stirred by stirring for about 10 minutes with a TK homogenizer.

Thereto, 30 g of hydrophilic silica (Aerosil 300) and 70 g of hydrophilic titanium dioxide (Aerosil P-25) were added, and the mixture was slowly stirred for 1 hour.

Then, the mixture was passed through a decompressor, dried with hot air at 50 to 60 ° C. for 3 hours and then vacuum dried at 50 to 60 ° C. for 5 hours, and then dispersed with a homogenizer at 2000 rpm for 5 minutes to obtain a fluidizing agent according to the present invention. A fine powder of a mixture of hydrophobic silica (average particle size 7 mμm) and hydrophobic titanium oxide (average particle size 30 mμm) is obtained.

[Synthesis Example 5] To 300 ml of toluene, 1 g of the zirco aluminum-based coupling agent Cabco Mod MPG (manufactured by Cabdon Chemical Co., Ltd.) was mixed, and stirred for about 10 minutes with a TK homogenizer to uniformly disperse.

100 g of fine powder of hydrophilic silica / aluminum oxide mixture (Aerosil MOX170) (manufactured by Nippon Aerosil Co., Ltd.) (hydrophilic silica: aluminum oxide = 99: 1) was added thereto,
Stir slowly for 1 hour.

Then, the mixture was passed through a decompressor, dried with hot air at 50 to 60 ° C. for 3 hours and then vacuum dried at 50 to 60 ° C. for 5 hours, and then dispersed with a homogenizer at 2000 rpm for 5 minutes to obtain a fluidizing agent according to the present invention. , A mixture of hydrophobic silica and hydrophobic aluminum oxide (average particle size 15 mμm) is obtained.

[Synthesis Example 6] To 250 ml of toluene, 5 g of acetoalkoxyaluminum diisopropylate was mixed, and mixed with a stirrer for about 20-30.
Stir for a minute to evenly disperse.

100 g of fine powder of hydrophilic titanium dioxide Aerosil P-25 (manufactured by Degussa) is added thereto and slowly stirred for about 1 hour.

After that, it was passed through a decompressor, dried with hot air at 80 to 85 ° C for 5 hours, and then vacuum dried at 100 ° C for 7 to 8 hours, and then dispersed at 2,000 rpm for 5 minutes with a TK homogenizer to obtain a fluidizing agent for comparison. Hydrophobized titanium oxide fine powder (average particle size 30m
μm) is obtained.

Example 1 Polyester resin (softening point 118 ° C., glass transition point 64
C.) 100 parts by weight and carbon black (Special Black 250) (manufactured by Degussa) 5 parts by weight are thoroughly mixed with a Henschel mixer. The mixture is kneaded with a twin-screw extruder, cooled, and coarsely crushed. The crushed product is crushed and classified by a jet crusher and an air classifier. An insulating toner having an average particle size of 13.0 μm and exhibiting a negative charging property is obtained.

Separately, 100 parts by weight of styrene-acrylic copolymer resin (Pryolite ACL) (made by Goodyear), 200 parts by weight of magnetic powder (Mapico Black 500) (made by Methane Industry Co., Ltd.), carbon black (MA # 8) (Mitsubishi Kasei) Manufactured by Kogyo Co., Ltd.) 4 parts by weight,
2 parts by weight of silica (# 200) (manufactured by Nippon Aerosil Co., Ltd.) are mixed by a ball mill and kneaded by a three-roll mill. The kneaded material is finely pulverized with a pin mill and classified with an air classifier. Average particle size
A positively chargeable microcarrier having a volume resistivity of 40 μm and a volume resistivity of 10 ¹⁴ Ω · cm is obtained.

Next, 0.5 wt% of hydrophobized titanium oxide fine powder (Synthesis example 1) was added to the insulating toner and mixed by a Henschel mixer for 1 minute at 1300 rpm, 50 parts by weight, and 450 parts by weight of the microcarrier. Are mixed to obtain a two-component developer A.

Using a developer A, a copier equipped with a positively chargeable Se-based photoreceptor and a Teflon-coated heat-fixing roll was used to develop a positive electrostatic image with a magnetic brush, and at the same time 60,000 sheets were continuously developed. Copying was performed, and changes in toner charge amount and image density were measured. The image density was measured using a reflection densitometer. The image portion potential of the electrostatic latent image is 600V, and the non-image portion potential is 150V.

Further, in the initial stage, the prepared developer was left under high temperature and high humidity (35 ° C., 85%) for 2 days, and the changes in the toner charge amount and the image density after that were measured.

Example 2 In place of the hydrophobized titanium oxide (Synthesis example 1), 0.3 w of fine powder of a mixture of hydrophobized silica and titanium hydrophobized (Synthesis example 4) was used.
A two-component developer B was prepared in the same manner as in Example 1 except that t% was added, and continuous copying was performed in the same manner as in Example 1 to measure changes in toner charge amount and image density.

Example 3 Two components were prepared in the same manner as in Example 1 except that 0.5 wt% of fine powder of a mixture of hydrophobized silica and hydrophobized aluminum oxide (Synthesis Example 5) was added in place of the hydrophobized titanium oxide (Synthesis Example 1). A system developer C was prepared and continuous copying was carried out in the same manner as in Example 1 to measure changes in toner charge amount and image density.

Example 4 Two components were prepared in the same manner as in Example 1 except that 0.3 wt% of fine powder of a mixture of hydrophobized silica and hydrophobized aluminum oxide (Synthesis Example 5) was added instead of hydrophobized titanium oxide (Synthesis Example 1). A system developer D was prepared and continuous copying was carried out in the same manner as in Example 1 to measure changes in toner charge amount and image density.

Example 5 Styrene-n-butyl methacrylate copolymer (softening point
120 ° C., glass transition point 60 ° C.) 100 parts by weight, carbon black (MA # 8) (manufactured by Mitsubishi Kasei Co., Ltd.) 5 parts by weight, charge control agent (Bontron N-01) (manufactured by Orient Chemical Co., Ltd.) 2 parts by weight, 2.5 parts by weight of Viscole 330p (manufactured by Sanyo Kasei Co., Ltd.) are thoroughly mixed with a Henschel mixer. The mixture is kneaded with a twin-screw extruder, cooled, and coarsely crushed. The crushed product is crushed and classified by a jet crusher and an air classifier. A toner having an average particle size of 13.0 μm and having a positive charging property is obtained. 0.2 w of a mixture of hydrophobized silica and hydrophobized aluminum (Synthesis Example 5) was added to this toner.
Two-component developer E is obtained in the same manner as in Example 1 except that t% is added and the mixture is mixed for 1 minute at 1300 rpm by a Henschel mixer.

Using a developer F, a copier equipped with a negatively chargeable CdS-based photoreceptor and a Teflon-coated heat-fixing roll was used to develop a negative electrostatic charge image by a magnetic brush development method, and 60,000 continuous sheets were developed. Copying was performed, and changes in toner charge amount and image density were measured. The image density was measured using a reflection densitometer. The image portion potential of the electrostatic latent image is -600V, and the non-image portion potential is -300V.

Example 6 A two-component system was used in the same manner as in Example 5 except that 0.5 wt% of fine powder of hydrophobized titanium oxide (Synthesis Example 1) was added instead of the mixture of hydrophobized silica and hydrophobized aluminum (Synthesis Example 5). Developer F was prepared and continuous copying was carried out in the same manner as in Example 5 to measure changes in toner charge amount and image density.

Example 7 A two-component developer in the same manner as in Example 5 except that 0.1 wt% of hydrophobized silica fine powder (Synthesis example 2) and 0.3 wt% of hydrophobized titanium oxide fine powder (Synthesis example 1) were added and mixed. G was prepared and continuous copying was carried out in the same manner as in Example 5 to measure changes in toner charge amount and image density.

Example 8 100 parts by weight of styrene-2 ethylhexyl acrylate copolymer (softening point 121 ° C., glass transition point 59 ° C.), magnetic component (EPT-500) (manufactured by Toda Kogyo Co., Ltd.) 40 parts by weight, negative charge control system (Bonitron) By using 3 parts by weight of R-04) (manufactured by Orient Chemical Co., Ltd.) and in the same manner as in Example 1, an insulating magnetic toner having an average particle diameter of 10 μm and exhibiting a negative charging property is obtained. 0.3 wt% of hydrophobized aluminum oxide fine powder (Synthesis Example 3) is mixed with this for 1 minute at 1300 rpm by a Henschel mixer to obtain a one-component developer H.

Using a copying machine equipped with a positively chargeable Se-based photoreceptor using the developer H and a Teflon-coated heat fixing roll, a positive electrostatic image is developed by a magnetic brush developing method, and 60,000 continuous copies are made. Then, the changes in the toner charge amount and the image density were measured.

Comparative Example 1 Instead of hydrophobized titanium oxide (Synthesis Example 1), a fine powder (average particle size) of hydrophobic silica (Aerosil R972) (manufactured by Nippon Aerosil Co., Ltd.) that was hydrophobized with a silane coupling agent (dimethyldichlorosilane). 16 mμm) was added in an amount of 0.2 wt% to prepare a two-component developer A ′ in the same manner as in Example 1, and continuous copying was performed in the same manner as in Example 1 to change the toner charge amount and the image density. It was measured.

Comparative Example 2 In place of the hydrophobized titanium oxide (Synthesis Example 1), 0.2 wt% of fine powder (average particle size 12 mμm) of hydrophilic silica (Aerosil 200) (manufactured by Nippon Aerosil Co., Ltd.) was added, except that in Example 1 A two-component developer B'was prepared in the same manner as in Example 1 and continuous copying was carried out in the same manner as in Example 1 to measure changes in toner charge amount and image density.

Comparative Example 3 Instead of the hydrophobized silica and hydrophobized aluminum mixture (Synthesis Example 5), hydrophilic titanium oxide (Aerosil P-25) was used.
A two-component developer C'was prepared in the same manner as in Example 5 except that 0.5% by weight of fine powder (average particle size: 30 mμm) was added, and continuous copying was carried out in the same manner as in Example 5 to obtain the toner charge amount. And the change in image density was measured.

Comparative Example 4 Instead of the hydrophobic silica and the hydrophobic aluminum mixture (Synthesis Example 5), a hydrophobic silica (Aerosil RX-170) (manufactured by Nippon Aerosil Co., Ltd.) which was hydrophobized with a silane coupling agent (dimethyldichlorosilane) was used. A two-component developer D'was prepared in the same manner as in Example 5 except that 0.2 wt% of fine powder (average particle size: 15 mμm) was added, and continuous copying was carried out in the same manner as in Example 5 to obtain the toner charge amount. And the change in image density was measured.

Comparative Example 5 Instead of the hydrophobized titanium oxide (Synthesis Example 1), silica.
A two-component developer E ′ was prepared in the same manner as in Example 1 except that 0.5 wt% of fine powder (average particle size: 5 mμm) of an aluminum oxide mixture (RX-C) (manufactured by Nippon Aerosil Co., Ltd.) was added. Further, continuous copying was performed in the same manner as in Example 1 to measure changes in toner charge amount and image density.

Comparative Example 6 Two-component developer F was prepared in the same manner as in Example 1 except that 0.5 wt% of fine powder of hydrophobized titanium oxide (Synthesis Example 6) was added instead of hydrophobized titanium oxide (Synthesis Example 1). ′ Was prepared and continuous copying was carried out in the same manner as in Example 1 to measure changes in toner charge amount and image density. In the initial stage, the prepared developer was exposed to high temperature and high humidity (35 ° C, 85%).
After leaving for one day, changes in the toner charge amount and the image density after that were measured.

In the case of Example 1, even after being left under high temperature and high humidity for 2 days, there is almost no change from the initial charge amount of −11.2 μc / g to −10.9 μc / g. 11.5μ
After being left under high temperature and high humidity for 2 days, the amount of charge was largely decreased to -8.1 μc / g, although the amount was substantially the same as that of Example 1, which was due to the hydrolyzability of the aluminum coupling agent. Yes because it is due to weakness in environmental changes.

Tables 1 and 2 show the results of the toner charge amounts and the image densities of Examples 1 to 8 and Comparative Examples 1 to 5 after copying 30,000 sheets and after copying 60,000 sheets, respectively. In addition, Table 3 shows a comparison of changes in the charge amount under high temperature and high humidity.

In the comparative example, in the initial stage, there was no fog and the resolution was high and the image was good, but as the copying was repeated, the toner charge amount and the image density changed greatly, and toner scattering or remarkable unevenness occurred in the image quality. There was a drawback.

EFFECTS OF THE INVENTION According to the present invention, a toner to which titanium oxide or aluminum oxide hydrophobized with a zirco aluminum-based coupling agent is externally added has an appropriate charge amount even after the toner is stored in a high humidity environment for a long time. In addition, even if the copying is repeated, the change in the toner charge amount is small and stable, the image density can be maintained at a high level, there is no problem in terms of fog resolution, and a copy image with good image quality can be obtained.

Claims (1)

[Claims] 1. An electrostatic latent image developer obtained by externally adding to a toner containing at least a thermoplastic resin and a colorant, titanium oxide or aluminum oxide that has been hydrophobized with a zirco aluminum coupling agent.