JPH1184742A - Liquid developer and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a superior image without blurring an image at the time of transfer the image to a subject for transfer by dispersing toner particles consisting essentially of a resin and a colorant in an insulating liq. and incorporating a wax soluble in the insulating liq. into the resultant liq. developer. SOLUTION: Toner particles consisting essentially of a resin and a colorant such as a pigment are dispersed in an insulating liq. such as a petroleum hydrocarbon carrier preferably by 0.1-20 wt.% and a wax soluble in the insulating liq. is incorporated into the resultant liq. developer by 0.001-10 wt.% to obtain the objective liq. developer as a full-color developer. Since the wax is added, electric charges of the liq. developer are stabilized and the developing performance is improved. A tougher image is formed at the time of developing a latent image and defacing and running can be prevented at the time of transfer to a subject for transfer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid developer and an image forming method using the liquid developer, and more particularly, to a method for developing an image by supplying an electrostatic latent image on an electrostatic latent image carrier. The present invention relates to an image forming method for transferring an image to a transfer target, and more specifically, to a liquid developer suitably used for image formation used for, for example, a copying machine or a laser beam printer, and an image forming method using the liquid developer. Things.

[0002]

2. Description of the Related Art A latent image formed on an electrostatic latent image carrier such as a photoreceptor can be developed using fine toner particles dispersed in a carrier solvent. The dispersed solution is known as a liquid toner or liquid developer. This liquid developer can form finer images since the toner particles can be made finer than a dry developer. A liquid developer disclosed in Japanese Patent No. -506941 is known.

However, after supplying and developing a liquid developer for the electrostatic latent image on the electrostatic latent image carrier, a developed image (an image formed by toner) visualized by the development is transferred. In the image forming method of transferring the image to the body, there is a problem that the image is disturbed when transferring the visible image to the object to be transferred.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks, and an object of the present invention is to provide a good image without disturbing the image at the time of transferring the image to a transfer target. An object of the present invention is to provide an obtained liquid developer.

Another object of the present invention is to provide an image forming method using the above liquid developer.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above object, and a liquid developer of the present invention comprises at least toner particles comprising a resin and a colorant dispersed in an insulating liquid. The liquid developer preferably contains 0.001 to 10% by weight of a wax dissolved in the insulating liquid. The liquid developer of the present invention is particularly useful as a full-color developer. is there.

In the image forming method of the present invention, a process of developing an electrostatic latent image on an electrostatic latent image carrier, and electrostatically transferring a visualized image formed by the developing to a transfer target is repeated. When forming a full-color image on the transfer target by
An image forming method characterized by using the above liquid developer as a developer, and developing an electrostatic latent image on an electrostatic latent image carrier, thereby forming a visualized image on a transfer target body. An image forming method, wherein the above liquid developer is used as a developer when a full-color image is formed on a transferred object by contacting and fixing an image on the transferred object with a heat roller after electrotransfer. Is the way.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The liquid developer of the present invention is obtained by dispersing toner particles comprising at least a resin and a colorant such as a pigment in an insulating liquid such as a carrier liquid of petroleum hydrocarbon, preferably 0.1%.
-20% by weight, and in the present invention, the wax dissolved in the insulating liquid further contains 0.001 to 1% by weight.
The content is 0% by weight.

The type of the wax used in the present invention is not particularly limited as long as it can be dissolved in an insulating liquid used as a carrier solvent described later. Such waxes include, for example, paraffin wax,
Synthetic waxes such as microcrystalline wax, alcohol wax and urethane wax.

[0010] Specific examples of the synthetic wax include HAD5080, HAD5090, and HAD567 manufactured by Nippon Seiro.
0, NPS9210, NPS6010, HNP-019
0, FT-100, OX-1949 (all trade names), and HW1105A manufactured by Mitsui Petrochemical Co., Ltd.
HW405MP (all are trade names).
These waxes are not necessarily 100% soluble in the insulating liquid, but the soluble component can be extracted by extracting the soluble component with the insulating liquid, and the dissolved component can be added to the liquid developer.

According to the present invention, it is not clear why the disturbance of an image at the time of transfer is suppressed by adding a wax soluble in an insulating liquid, but the liquid developer is added by adding a wax soluble in the insulating liquid. This is considered to be because the electric charge of the sample is stabilized and the developability is improved. That is, it is considered that, by improving the developability, a stronger image is formed when the latent image is developed, and as a result, the collapse and the flow at the time of transfer to the transfer object are prevented.

Although the content of the wax dissolved in the insulating liquid contained in the liquid developer of the present invention is not particularly limited,
Preferably it is 0.001 to 10% by weight, more preferably 0.05 to 5% by weight. If the content of the wax is too small, the effect of preventing the disorder of the image intended in the present invention cannot be obtained, and if it is too large, the conductivity of the solution becomes too high and the print density is lowered.

In the production of the liquid developer of the present invention, these waxes may be added when the toner particles are dispersed.
Also, it may be added when diluting with an insulating liquid.

The insulating liquid used in the present invention has a volume resistivity of preferably 10 ¹⁴ Ω · cm or more, and its boiling point range is preferably 200 ° C. to 280 ° C., more preferably 210 ° C. to 260 ° C. It is below ° C. The insulating liquid preferably has a difference in kinematic viscosity between a value at 10 ° C. and a value at 50 ° C. of preferably 3 cst or less, more preferably 2 cst.
And the kinematic viscosity at 20 ° C. is preferably 1 c
It is preferable to use one having a length of st to 4 cst, more preferably 1.5 cst to 3.5 cst.

Here, when the boiling point is less than 200 ° C.,
In some cases, the solvent evaporates on the electrostatic latent image carrier, and the state of the developer at the time of transfer to the transfer target changes, resulting in unstable transfer. If the boiling point exceeds 280 ° C., the energy required for fixing the toner image on the transfer medium increases, which may be undesirable in terms of the device configuration.

If the kinematic viscosity at 20 ° C. is less than 1 cst, the developer in the non-image area on the electrostatic latent image carrier cannot be sufficiently removed, and soiling may occur. On the other hand, if it exceeds 4 cst, the time required for development becomes longer, and the printing speed of the printer may be reduced.

If the difference between the kinematic viscosity at 10 ° C. and the value at 50 ° C. exceeds 3 cst, the image forming method of supplying a liquid developer via a developing roller to develop the liquid developer. The temperature dependence of the kinematic viscosity is linked to the temperature dependence of the development density, and the print density of the printed matter changes depending on the temperature because the property depends on the mobility of the toner particles in the liquid developer and, consequently, the viscosity of the solvent. Problem may occur.

If the volume resistivity is less than 10 ¹⁴ Ω · cm, the toner particles in the liquid developer may not be electrophoresed well and the latent image may not be sufficiently developed.

As such an insulating liquid (carrier solvent) used in the present invention, a petroleum hydrocarbon-based insulating solvent is preferable, and specific examples thereof include Isopar L and M.
(Manufactured by Exxon Chemical Co., Ltd./trade name), JWS8947 (manufactured by Esso Oil Co., Ltd./trade name), Isosol 400 (manufactured by Nippon Petrochemical Co., Ltd.), NP-LC, NP-HCS, NP
-SH (manufactured by Mitsui Texaco Chemical Company / brand name) and N
AS-4 (manufactured by Nippon Yushi Co., Ltd./trade name) is preferred, and more preferably, Isopar M, JWS8947, Isosol 400, NP-LC, NP-HCS, NP-SH,
NAS-4, more preferably JWS8947, NP-
HCS.

As described above, the liquid developer of the present invention is obtained by dispersing colored toner particles containing a colorant and a resin as main components in a carrier liquid of petroleum hydrocarbon, preferably in an amount of 0.1 to 20% by weight. However, the average particle size of the colored toner particles is preferably 0.3 to 5 μm, more preferably 0.5 to 5 μm.
3 μm. If the average particle size of the toner particles is less than 0.3 μm, there arises a problem that the print density is not sufficient and the gloss of the printed matter is not sufficient, and the average particle size is 5 μm.
When m is larger than m, the particle size of the colored particles with respect to the pixel becomes large, and an image may be roughened on a thin line of a printed matter.

The average particle size of the toner particles is SHIMADZ.
It can be measured by a USA-CP3 centrifuge particle size distribution analyzer. That is, the liquid developer is diluted with a dispersion medium so as to match the absorbance measurement range of the measuring device.
Then, this sample is measured by measuring the particle distribution from the change in absorbance in the acceleration rotation mode at 2400 RPM / min, and calculating the average particle diameter by the median diameter.

The toner particles are mainly composed of a coloring agent composed of a pigment or a dye and a binder resin. In the present invention, colored toner particles in which a pigment is dispersed in a resin are preferable. The ratio of the pigment in the colored toner particles is preferably 5% by weight.
Not less than 30% by weight, more preferably not less than 10% by weight 2
5% by weight or less. When the amount is less than 5% by weight, the coloring power becomes insufficient, and when the amount exceeds 30% by weight, the fixability becomes insufficient, and there may be a problem in glossiness of printed matter.

The resin used in the present invention includes:
Examples thereof include alkyd resins, styrene resins, phenol resins, acrylic resins, styrene-acryl resins, polyester resins, rosin-modified phenol resins, and rosin-modified resins. It is preferable to use rosin-modified resins. More preferably, the resin has an acid value of 50 to 250, a softening point of 70 to 150 ° C., and a ratio of gum rosin in rosin of 20% or more.

As the rosin-modified resin, it is preferable to use rosin-modified maleic resin and rosin-modified fumaric resin, and specific examples thereof include FGM-3 manufactured by Arakawa Chemical Co., Ltd.
10, FGM-312 (all are trade names), UNION
UNIREZ 709, 710, 811 manufactured by CAP
2, 8115 (both are trade names).

If the acid value of the rosin-modified resin is less than 50, the chargeability may be poor, and if it exceeds 250, the dispersibility in an insulating liquid may be poor. The measurement of the acid value here was in accordance with the description in “Painting Handbook” (edited by Shinji Iwai, published by Sangyo Tosho 1927, p.635).

In the present invention, if the softening point of the rosin-modified resin is lower than 70 ° C., the storage stability becomes poor.
If the ratio exceeds the above range, the fixability may be poor. Further, when the ratio of gum rosin in the rosin of the rosin-modified resin is less than 20%, the stain on the white background may be poor.

As pigments and dyes which are colorants used in the present invention, general ones are used.
Carbon black (a commercially available product such as # 3 manufactured by Mitsubishi Kasei Co., Ltd.
0, # 40, # 50, MA-7, 11, 100, 220
(Trade name), MONARCH 800, 9 manufactured by Cabot Corporation
00, MOGUL-L, BLACK PEARLS13
0, REGAL 330, 400, 660R (trade name),
Columbia Carbon Co. Raven 1255, 102
It is also possible to mix an alkali blue or the like with carbon black in addition to 0, 1000 (trade name).

If it is yellowish, C.I. I. Pigment
Yellow-1,3,4,5,6,12,13,1
4,15,16,17,18,24,55,65,7
3,74,81,83,87,93,94,95,9
7, 98, 100, 101, 104, 108, 109,
110, 113, 116, 117, 120, 123, 1
28,129,133,138,139,147,15
1,153,154,155,156,168,16
9, 170, 171, 172, 173, and C.I.
I. Pigment Yellow-12, 13, 1
It is preferred to use 4, 17, 81, 95, 109, 154.

If it is reddish, C.I. I. Pigment
Red-1, 2, 3, 4, 5, 6, 7, 8, 9, 10,
12, 14, 15, 17, 18, 22, 23, 31, 3
7, 38, 41, 42, 48: 1, 48: 2, 48:
3,48: 4,49: 1,49: 2,50: 1,52:
1,52: 2,53: 1,54,57: 1,58: 4
60: 1, 63: 1, 63: 2, 64: 1, 65,6
6, 67, 68, 81, 83, 88, 90, 90: 1,
112, 114, 115, 122, 123, 133, 1
44,146,147,149,150,151,16
6,168,170,171,172,174,17
5,176,177,178,179,185,18
7,188,189,190,193,194,20
2,208,209,214,216,220,22
1,224,242,243,243: 1,245,2
46,247, and C.I. I. Pigment Re
d-31, 48: 3, 57: 1, 81, 122 are preferred.

If the color is blue, C.I. I. Pigment
Blue-1, 2, 9, 14, 15, 16, 17: 1,
19, 21, 22, 24, 25, 56, 60, 61, 6
3,64, and C.I. I. Pigment Blue
-15 is preferred.

Besides, phthalocyanine green, oil violet, methyl orange, methyl violet and the like are used.

The colored toner particles are mainly composed of a pigment, a dye or a resin, but may be added with polyethylene glycol or polypropylene glycol for adjusting the softening point.

Further, a charge control agent may be blended in the particles for charge control, or the charge control agent may be added to the surface of the particles. By appropriately selecting the charge control agent, it is possible to charge both positively and negatively. Examples of the charge control agent include, but are not limited to, low molecular weight lecithin, barium petronate, sodium alkyl succinate, cobalt naphate, aluminum stearate, cobalt octate, zirconium naphthate, quaternary ammonium salt, and tertiary amine. In addition to the above, a polymeric charge control agent can be used.

The content of the charge control agent in the liquid developer is not particularly limited, but is preferably 0.0001 to 70% by weight in the liquid developer.

In the present invention, particularly, a graft-type amphiphilic polymer having sites compatible with each of the insulating liquid and the resin is preferably used because the charge is stable. Examples of the portion that is soluble in the insulating liquid include, for example,
Higher fatty acid vinyl ester, vinyl alkyl ether,
Examples include polymers polymerized from alkyl acrylates and alkyl methacrylates.
Examples of the portion soluble in the resin include, for example, polymers polymerized from vinyl acetate, vinyl chloride, methacrylic acid, methyl acrylate, methyl methacrylate, acrylonitrile, dialkylaminoalkyl acrylate, and the like. However, the present invention is not limited to this. Another example of such an amphiphilic polymer is a polymer described in JP-B-60-15063.

In order to produce the liquid developer of the present invention, specifically, a resin and a coloring material are melt-kneaded by applying heat with a twin-screw extruder, a kneader, or the like, and after coarsely pulverized, charge control is performed. In a petroleum-based hydrocarbon-based insulating liquid together with additives such as chemicals and wax, it can be dispersed using a ball mill, vibrating mill, and attritor to obtain a conc toner having a predetermined particle size and particle distribution. The liquid developer is obtained by further diluting this with an insulating solvent.

Next, the image forming method of the present invention will be described.

The liquid developer of the present invention is used for developing an electrostatic latent image on an electrostatic latent image carrier to visualize it. Electronic recording paper,
There are a selenium-based photoconductor, an organic photoconductor, and an amorphous silicon photoconductor. When a photoreceptor is used as the electrostatic latent image carrier, a visualized image on the photoreceptor that has been visualized by development is transferred to a transfer target such as paper and fixed. When a full-color image is formed using a color toner, for example, an electrostatic latent image on an electrostatic latent image carrier is developed with a liquid toner,
By repeating the process of electrostatically transferring the visualized image visualized by the development onto the image receiving body, a full-color image is formed on the image receiving body, and the image finally formed on the image receiving body is fixed. There is a method.

The transfer material referred to in the present invention includes:
Any kind of paper, plastic film, metal, cloth, board, etc. can be used as long as it can be printed normally.

These image forming methods are suitably used, for example, in copying machines and laser beam printers.

[0041]

Next, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

Example 1 1420 g of rosin-modified maleic resin (Unilet's 709, acid value 110, softening point 120 ° C., manufactured by Union Camp Co.), Lionol Re
d6B FG4213 (manufactured by Toyo Ink Mfg. Co., Ltd.) 400
g and 180 g of polyethylene glycol (PEG 6000P, manufactured by Sanyo Kasei Co., Ltd.) were preliminarily mixed with a mixer and then melt-kneaded using a twin screw extruder (feed amount 2 kg).
/ Hr, temperature 100 ° C). After cooling the obtained melt-kneaded material, a coarse powder having a particle size of about 50 μm was obtained using a sample mill. 200 g of this coarse powder and 54 g of an acrylic polymer type charge control agent solution (produced by the method described in Example XI of US Pat. No. 3,900,412, solid content 14%)
%), 1209 g of Isopar M (manufactured by Exxon Chemical) having a volume resistivity of 1014 Ω · cm or more and paraffin wax HNP-01 extracted by Isopar M
90 (manufactured by Nippon Seiro Co., Ltd.) and 16 parts of "Isopar" M dissolved component were mixed and crushed by a vibration mill for 5 hours to obtain a liquid toner having an average particle diameter of 1.2 μm. This stock solution was diluted to a solid concentration of 2.0% to obtain a liquid developer.

Next, at a room temperature of 20 ° C., using the Se drum as a photosensitive member, the liquid developer thus obtained is developed with a developing roller at a linear speed of the photosensitive member of 120 mm / sec. An image is electrostatically transferred on art paper on which a toner image formed on a body is stuck on a transfer drum, a linear pressure of 20 kg is applied to the image, and the image is fixed at a pressure roller temperature of 200 ° C. In addition, an image having a print density of 1.4 with no white background stain and no image disturbance was obtained. further,
When these prints were enlarged and examined with a microscope, it was found that there was no disturbance in the shape of the fine halftone dots, and that a good image was obtained in which fine lines of 30 μm were smooth and free of roughness.

Comparative Example 1 HNP-0190 of Example 1
A liquid developer was obtained in the same manner as in Example 1, except that the "Isopar" M dissolved component (manufactured by Nippon Seiro) was removed. When the same evaluation as in Example 1 was performed using this liquid developer, crushing and image deletion occurred, and the image density was 0.85.
It was a low printed matter.

Example 2 1420 parts of rosin-modified maleic resin (FGM310, acid value 100, softening point 120 ° C., manufactured by Arakawa Chemical Co., Ltd.), carbon black (MOGUL-
L, manufactured by CABOT) 400 parts, polyethylene glyco-
After 180 parts of PEG 6000P (manufactured by Sanyo Chemical Co., Ltd.) was preliminarily mixed by a mixer, the mixture was melt-kneaded using a twin-screw extruder (feed amount: 2 kg / hr, temperature: 120 ° C.). After cooling the obtained melt-kneaded material, a coarse powder having a particle size of about 50 μm was obtained using a sample mill. 200 parts of this coarse powder and 108 g of an acrylic polymer type charge control agent solution (solid content 14
%) And a solvent having the following characteristics (JWS manufactured by Esso Oil Co., Ltd.)
8947) Volume specific resistance 1014 Ω · cm or more Kinematic viscosity at 20 ° C. 2.5 cst Boiling point range 225 ° C. to 242 ° C. Mix 1509 g of a difference of kinematic viscosity between 50 ° C. and 10 ° C. 1.57 cst 1209 g, and shake with a vibration mill for 5 hours This was pulverized to obtain a stock solution of toner.

The undiluted solution was diluted to a solid concentration of 1.5%, and the urethane wax HAD5080 (manufactured by Nippon Seirozu Co., Ltd.) extracted with JWS8947 was used in JWS8947.
The dissolved component was added so that the solid content concentration became 0.3% to obtain a liquid developer. The same evaluation as in Example 1 was performed using this liquid developer. As a result, it was possible to obtain a good printed matter having no image collapse and image deletion and an image density of 1.36.

(Comparative Example 2) HAD5080 of Example 1
A liquid developer was obtained in the same manner as in Example 2 except that the JWS8947 dissolved component (manufactured by Nippon Seiro) was removed. When the same evaluation as in Example 1 was performed using this liquid developer, crushing and image deletion occurred, and the printed matter had a low image density of 0.89.

[0048]

According to the present invention, by using the liquid developer of the present invention, it is possible to obtain a good image having a high image density and free from crushing or running. Further, a clear full-color image can be formed by a copying machine, a laser beam printer, or the like.

Claims (5)

[Claims] 1. A liquid developer comprising: a liquid developer in which toner particles comprising at least a resin and a colorant are dispersed in an insulating liquid; and a wax dissolved in the insulating liquid. 2. The content of the wax is 0.001 to 1
2. The liquid developer according to claim 1, wherein the amount is 0% by weight. 3. The liquid developer according to claim 1, wherein the liquid developer is a full-color developer. 4. A full-color image is formed on a transfer-receiving member by developing the electrostatic latent image on the electrostatic-latent-image-bearing member with a developer, and electrostatically transferring the visualized image formed on the electrostatic latent image onto the transfer-receiving member. An image forming method, wherein the liquid developer according to any one of claims 1 to 3 is used as a developer when forming the image. 5. An electrostatic latent image on an electrostatic latent image carrier is developed,
After electrostatically transferring the visualized image formed by this to the transfer receiving body, the image on the transfer receiving body is contacted with a heat roller and fixed to form a full-color image on the transfer receiving body. An image forming method using the liquid developer according to any one of claims 1 to 3.