JPS60112052A - Toner composition for electrophotographic developer - Google Patents

Abstract

PURPOSE:To shorten the rise time of quantity of electrostatic charge of a toner and to prevent image deterioration in making a large number of copies by using a binder resin composed essentially of a specified polyester resin, and incorporating a specified amt. of anatase type TiO2. CONSTITUTION:A polyester resin used for the binder resin for a toner is obtained by polymerizing an acid component consisting of bi-valent or higher valent carboxylic acid, its anhydride, or its lower alkyl ester, and an diol component represented by formula I in which R is ethylene or propylene group, x, y are each an integer of >=1, and the average value of the sum of them is 2-7. An anatase type TiO2 is contained in an amt. of 0.01-5wt%. Such a polyester resin has a softening point of 100-180 deg.C measured by the ring and ball method. Said TiO2 has an average particle diameter of <=500mum. The use of the toner of such a compsn. permits the toner to rapidly reach a satd. charge amt. and the rise time to be shortened, and a sharp copy free from background stains to be obtained, and it prevents deterioration of images, such as background stains, and whitened solid black parts, in making a large number of copies.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a toner composition for a developer for developing electrostatic images in electrophotography, electrostatic recording, electrostatic printing, and the like. More specifically, the present invention relates to a toner composition for a developer that can provide clear images without fogging in high-speed electrophotography.

As a conventional electrophotographic method, as described in U.S. Patent Nos. 2,297,691 and 2,357,809, etc.
Step 1: Uniformly charging a photoconductive insulating layer, then exposing the layer to light, and dissipating the charge on the exposed portions of the layer.
to form an electrical latent image, and then make it visible by depositing a colored, electrically charged fine powder called toner on the latent image (developing process), and transfer the resulting visible image to transfer paper, etc. After the image is transferred onto a transfer material (transfer step), it is permanently fixed by heating, pressure or other suitable fixing method (fixing step).

Two-component development is a common method for visualizing an a-image using toner. The developing method is U.S. Patent No. 2518.
The cascade development method described in US Pat. No. 551, and the magnetic brush method described in US Pat. No. 2,786,459 and US Pat.
A mixture of carriers that has the function of triboelectrically charging the toner and causing the toner to adhere to the latent image surface depending on the charge is used as the developer. - In the case of Kono, the toner is made by mixing a resin such as polystyrene, styrene acrylic resin, phenol resin, or polyester resin with a pigment such as carbon black, and optionally a dye to control lume load in an appropriate ratio, and then heat-melting the mixture.
Use the one that has been solidified and pulverized to a size of 10 to 15 μm. On the other hand, conductive metal coarse particles having a size of several tens of micrometers to several hundreds of micrometers/jm are used as carriers.

When a large number of sheets are continuously copied using the above-mentioned developer, image deterioration occurs as a result of the continuous copying.

Regarding the phenomenon of image deterioration, there is a decrease in image density, ground cover,
In addition to general deterioration phenomena such as the occurrence of spent toner and an increase in the amount of toner charge, image deterioration is also observed when the amount of charge of toner increases slowly.
Toner scattering occurs.

The purpose of the present invention is to improve the deterioration phenomenon of the developer during copying of a large number of sheets as described above, and more specifically, to speed up the rise time of toner static electricity, thereby improving the image quality during copying of a large number of sheets. The goal is to improve the deterioration of

Another object of the present invention is to provide a developer with good fixing properties and non-setting properties in a heat roller fixing system.

In order to achieve the above object, the present inventors have arrived at the present invention as a result of intensive research.

That is, the present invention provides a toner composition for a developer comprising a binder resin and a colorant, in which the main components of the H binder resin are a diol component represented by the following general formula (II) and a carboxylic acid having a divalent value of 4 or more. or an acid component consisting of its acid anhydride or its lower alkyl ester. This relates to a toner composition for X developer.

Examples of the diol component represented by the above general formula (I) in the present invention include polyoxybupyrene (2,2) -
2,2-bis(4-hydroxyphenyl)propane, polyoxypropylene (5,5) -2-,2-bis(4
-hydroxyphenyl)propane, polyoxyethylene(2,0) -2,2-bis(4-hydroxyphenyl)propane-polyoxypropylene(2,0)-polyoxyethylene(2,0) -2 , 2-bis(4-hydroxyphenyl)propylene, polyoxypropylene f6)
-2,2-bis(4-hydroxyphenyl) hydrogen and the like can be mentioned.

Examples of divalent or higher carboxylic acids that can be used in the present invention include nmaric acid, maleic acid, phthalic acid, n-dodecenyl succinic acid, indodecenyl succinic acid, n-dodecyl succinic acid, indodecyl succinic acid, and n-octyl succinic acid. acid, n
-Octenyl and alkyl or alkenyl succinic acids such as citric acid, n-butylsuccinic acid, trimellitic acid, pyromellitic acid, 3-methyl-4-hegetyl-5-methyl-1
, 2,6,7-hegutene(4)-tetracarboxylic acid and the like, preferably used in a mixed system.

Ring and ball softening point (ASTM) of the polyester resin of the present invention
E28-51T) is preferably 100 to 180C.

As the binder resin in the present invention, there is no problem in using the above-mentioned polyester resin in combination with a known binder resin, if necessary.

The anatase type titanium oxide used in the present invention has a lattice constant (Ta) of 3.78A and a lattice constant (b) of 9.
49A, dielectric constant 50 or less and average particle diameter 500mμ or more1
A fine powder of is preferred, and examples thereof include A-+oo, A-220 (manufactured by Ishihara Sangyo Co., Ltd.), #110, +200 (manufactured by Teikoku Kako Co., Ltd.), and P-25 (manufactured by Degussa Corporation).

Examples of the coloring agent used in the present invention include carbon black, acetylene black, phthalocyanine blue, rhodamine B pace, Solvent Red 49, Solvent Red 146, etc., and usually 1 to 1
5% by weight is used.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example-1 Polyoxypropylene (2,2) -2,2-bis(4
-Hydroxyphenyl)propane 7709, 170 g of ummaric acid, 87 g of trimellitic anhydride, 1 J34 of hydride tetraquinone (polymerization inhibitor) O, S, and V were placed in a flask, and a dehydration tube, an 8 element introduction tube, and a cooling device were attached. 85 parts by weight of a polyester resin placed in a heating mantle and reacted at 220C in a nitrogen stream and extracted when the softening point reached 125CK, and a commercially available styrene-butyl acrylate copolymer (softening point +53r) 15 '4
Amount BB and carbon black (Zigal 400R manufactured by Cabot Co., Ltd.) lOffi:kt were mixed in a ball mill, melted and kneaded in a kneader, and finely pulverized in a jet mill to obtain a toner having an average particle size of 12 μm. 130 parts by weight of the toner and 1 part of anatase titanium oxide 1200 (manufactured by Teikoku Kako Co., Ltd.)
6 parts by weight were added and stirred vigorously. This titanium oxide treated toner was further added to iron powder E'FV (manufactured by Nippon Tetsuko Co., Ltd.) 1170I.
In addition, the developer was adjusted.

When the developer was put into the developing device of a copying machine 5F850 (manufactured by Sharp Corporation) and toner which had been similarly treated with titanium oxide was put into the toner supply device and an image was produced, a clear copy with no background stains was obtained. Even after copying 10,000 copies, no image deterioration such as smudging or fading of black areas was observed. Iron powder 460I was placed in a 500 cc poly bottle, titanium oxide treated toner 409 was added, and the bottle was placed on a ball mill stand and stirred at a rotational speed of 90 rpm.The charge amount of the toner was measured over time, and the charge amount after 5 minutes was 2.
There was no difference at all from the change in the amount of charge after stirring for hours.

On the other hand, when we performed the same evaluation using a toner that was not treated with titanium oxide, there was severe background smudge from the beginning of the image output (fading of the black areas had already occurred on the 2000th sheet.) The change was that the amount of charge 5 minutes after stirring reached only 60% of the amount of charge after 2 hours of stirring.

Evaluation was performed in exactly the same manner except that hydrophobic silica (R-972; manufactured by Nippon Aerosil Co., Ltd.) was used as a substitute for titanium oxide, and the initial image was clear with no background stains, but after 5,000 sheets. I have already noticed an increase in smudges and dark patches on my eyes. When the change in the amount of charge was measured using a ball mill, it was found that the amount of charge after stirring for 5 minutes reached only 70% of the amount of charge after stirring for 2 hours.

Example-2 Polyoxypropylene (2,2) -2,2-bis(4
-hydroxyphenyl)propane 318511 polyoxyethylene(2)-2,2-bis(4-hydroxyphenyl)propane 126BIi, (sophthalic acid 1327.
! i' was placed in a 514-ml flask and reacted sufficiently at J220t:' using the same apparatus as in Example 1, and 512 g of trimellitic anhydride was added thereto and reacted at 220C. When the softening point reached +60 CVC, the reaction was stopped and a pale yellow polyester resin was obtained.

The resin 960I and carbon black Neo Spectra Mark 70.9 (manufactured by Columbian Carbon) were mixed in a ball mill, kneaded in a kneader, and pulverized in a jet mill to obtain a toner having an average particle size of 12 μm. o, s to the toner
H-% anatase type titanium oxide (manufactured by Degussa, average particle size 30 mμ) was added and vigorously stirred to obtain a titanium oxide treated toner. Mix with iron powder, adjust the developer to ff, M, and copy machine PC
When the titanium oxide treated toner was put into a +32 (Sanda Kogyo Co., Ltd.) developing device and a toner supply device was put into it, a clear image was obtained. Continuous copying was performed up to 50,000 sheets, but clear images that were completely unchanged from the initial images were obtained, and no deterioration phenomenon was observed.

In place of anatase titanium oxide, rutile titanium oxide (
When we processed the toner using Teikoku Kako Co., Ltd. (average particle size 30i0μ) and performed a similar evaluation, the initial image was clear, but when continuous copying was performed, toner scattered from inside the developing device. After copying 20,000 copies, toner inside the copying machine became smudged, and the images also became more smudged. Example-1
Similarly, when measuring changes in the charging cap, the toner treated with anatase type titanium oxide reached a sufficient saturated charge amount after 5 minutes of stirring in a ball mill, while the toner treated with rutile type titanium oxide reached a sufficiently saturated charge amount after 5 minutes of stirring and 2 hours of stirring. The amount of charge reached only 80% of the amount of charge.

Comparative Example 1 The toner prototyped in Example-2 was subjected to the same operations as in Example-2 without surface treatment, and image evaluation was performed. During continuous copying, toner scattering was already observed at the 5000th mark.

In addition, instead of anatase-type titanium oxide, hydrophobic silica (average particle size 20 mμ), which is known as a fluidity improver, was used.
．． When 3% or 0.5% was added and the same evaluation as in Example 2 was performed, the fluidity of the toner improved and the initial image was clear with no background fog, but after the 10,000th print, Toner scattering was observed, and pond fungus was occurring.

Furthermore, instead of anatase titanium oxide, aluminum oxide, tin oxide, calcium carbonate fine powder (average particle size 5
Although the same evaluation as in Example 2 was carried out using silica (00 mμ or less), no material having an effect superior to that of hydrophobic silica was found.

Applicant's agent Kaoru Furutani

Claims (1)

[Claims] 1. In a toner composition for a developer comprising a binder resin and a colorant, the main component of the binder M resin is a diol component represented by the following general formula (1) and a diol component or more. A polyester resin H3 obtained by polymerizing a carboxylic acid, its acid anhydride, or its lower alkyl ester with an acid component consisting of a carboxylic acid, its acid anhydride, or its lower alkyl ester. Toner composition 2 for electrophotographic developer, ring and ball softening point of polyester resin (ASTME2
Claim F in which B-51T) is 100 to 180C
The toner composition according to IJJ item 1 & the toner composition according to claim 1, wherein the average particle size of the anatase titanium oxide is 500 mμ or less