JPH08272153A - Liquid toner - Google Patents

Abstract

PURPOSE: To provide a liquid toner which can be laid in a stack even when a high quality paper having a high surface flatness/smoothness is used, two-sided printing is conducted, and under high temp. in summer and which ensures stability in preservation by determining specifically the mix proportion of the binder resin for toner particles and the fat having a specific iodine value. CONSTITUTION: A liquid toner for development of electrostatic latent image of such a structure that toner particles at least containing a binder resin and pigment are dispersed in a dispersion medium. wherein the composition of the toner particles consists of 100 parts by wt. binder resin and 5-50 parts by wt. fat having an iodine value of 130 or more. At least toner particles containing a coloring agent such as pigment or dye and fat having an iodine value of 130 or more in the binder resin are dispersed in a solvent of insulative nature. The quantity of this sort of fat will be 5-50 parts by wt., more favorably between 10-40 parts by wt., relative to 100 parts by wt. binder resin. A smaller quantity of fat decreases the improving effect of the stacking characteristic, while a greater quantity of fat worsens the stability in preservation to lead to drop of the easiness in works of crushing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid toner used in an image forming method for developing an electrostatic latent image on an electrostatic latent image carrier with a liquid toner, such as a copying machine or a laser. -Used for beam printers.

[0002]

2. Description of the Related Art For example, in U.S. Pat. No. 3,257,322, a pigment is dispersed in a varnish prepared by heat-kneading 1 part by weight of hydrogenated rosin and 4 parts by weight of polymerized linseed oil (phosphorus seed oil). Furthermore, a liquid toner prepared by dispersing it in a hydrocarbon solvent is disclosed.

[0003]

Generally, printed matters prepared by using a copying machine or a laser beam printer may adhere to each other due to their own weight when placed one on top of the other, impairing the printed surface. . This is particularly likely to cause a problem when using high-quality paper having high surface smoothness, when performing double-sided printing, or when the temperature is high in summer. The inability to stack the sheets on top of each other is a fatal drawback for printers and the like that are intended for use in the field of small-lot printing.

In the composition containing linseed oil as the main component as in the above-mentioned conventional example, the viscosity of the varnish itself is too high, and the printed matters tend to adhere to each other. In addition, there is a problem in storage stability as a liquid toner, and the toner particles once settled are solidified and difficult to redisperse.

The object of the present invention is to solve the above-mentioned problems, and even when high quality paper having a high surface smoothness is used, double-sided printing is performed, and even when the temperature is high in the summer, the sheets can be stacked.
Another object of the present invention is to provide a liquid toner for electrostatic latent image development which has good storage stability.

[0006]

DISCLOSURE OF THE INVENTION As a result of intensive investigations by the present inventors in order to achieve the above-mentioned liquid toner, an iodine value of 130 is added to 100 parts by weight of the binder resin component in the toner particles. The present invention has been completed by finding that the above objects can be achieved by containing 5 to 50 parts by weight of the above fats and oils.

That is, the present invention provides a liquid toner for developing an electrostatic latent image in which toner particles containing at least a binder resin and a colorant are dispersed in a dispersion medium, wherein the toner particles are the binder resin component. A liquid toner for developing an electrostatic latent image, comprising 5 to 50 parts by weight of an oil or fat having an iodine value of 130 or more based on 100 parts by weight.

The present invention will be described in detail below.

The liquid toner of the present invention contains at least a coloring agent such as a pigment or a dye and an iodine value of 13 in the binder resin.
Toner particles containing 0 or more oil and fat are dispersed in an insulating solvent.

Examples of the binder resin used in the toner of the present invention include polyester resin, styrene resin, acrylic resin, epoxy resin, rosin, rosin modified resin, styrene-acrylic copolymer resin, styrene-butadiene copolymer resin. And so on. Further, these resins may be mixed and used. Of these, a rosin-modified resin and a mixture containing a rosin-modified resin are preferable from the viewpoint of compatibility with fats and oils and pulverizability of a kneaded product. As a rosin,
Gum rosin, toluoyl rosin, polymerized rosin and the like can be used, and as the rosin modified resin, for example, disproportionated rosin such as Longis R, Longis K-80 (manufactured by Arakawa Chemical Industry Co., Ltd.), ester gum H, HP (Arakawa Chemical Industry Co., Ltd. (Made by the company)
Hydrogenated rosin ester such as Tamanor 135, 14
5,350 (manufactured by Arakawa Chemical Industry Co., Ltd.) and the like, phenol-modified rosin, Uniletz 709 (manufactured by Union Camp Co., Ltd.) and other rosin-modified maleic acid resins, Uniretz 8112
Examples include rosin-modified fumaric acid resins such as (made by Union Camp). In the case of a mixture containing a rosin-modified resin, the proportion of the rosin-modified resin in the binder resin component is preferably 70% by weight or more. If the proportion of the rosin-modified resin is too low, the good pulverizability of the rosin-modified resin will decrease. Further, the mixed resins may cause phase separation.

Examples of fats and oils having an iodine value of 130 or more used in the toner of the present invention include natural fats and oils such as linseed oil, eno oil, and tung oil, but are not limited thereto and synthetic fats and oils. I don't care. The fats and oils having an iodine value of 130 or more contained in the toner are fixed on a support such as paper and then exposed to the air to be solidified in a relatively short time to form an oxide polymerized film on the surface layer of the visible image. . This makes it possible to prevent the printed matter from adhering to each other even when the printed matter is placed on top of each other.

The iodine value is the number of grams of iodine absorbed in 100 g of fat. The larger this value is, the higher the degree of unsaturation of the fatty acid in the sample is, and it is oxidatively polymerized when left in the air. It becomes easy to solidify. Although the upper limit of the iodine value is not particularly limited for the purpose of the present invention, the iodine value is preferably 300 or less from the viewpoint of stability during heat kneading.

The amount of the oil having an iodine value of 130 or more is preferably 5 to 50 parts by weight, more preferably 10 to 40 parts by weight, based on 100 parts by weight of the binder resin component. If the amount of fats and oils having an iodine value of 130 or more is too small, the effect of improving the stackability is reduced. Further, if the amount of the oil / fat is too large, the storage stability becomes poor and the pulverizability also deteriorates.

Examples of the colorant used in the toner of the present invention include black colorants such as carbon black and alkali blue pigments, and Sudan black and other dyes.
Examples of magenta colorants include C.I. I. Pigment 122,
C. I. Pigment Violet 19 and other quinacridone-based pigments, Rhodamin 6G lake, Rhodamin B-lake and other rotamine-based pigments, C.I. I. Pigment Red 5
7: 1 (Brilliant Carmine 6B), azo pigments such as lysol rubin GK, lionol red and lake red, C.I. I. Solvent Red 49, C.I. I. Solvent Red 19, C.I. I. Examples of dyes such as Solvent Red 52 and cyan colorants include C.I. I. Pigment Blue 15 (Phthalocyan Nimble), Heliogen Bull-G,
Phthalocyanine-based pigments such as fast sky blue,
C. I. Solvent Bull-25, C.I. I. Solvent Bull-70, C.I. I. Dyes such as Solvent Bull-40,
As a yellow colorant, a disazo pigment (C.I. Pigment Yellow 12, 13, 14, 15, 16, 1
7, 55, 81, 83, 87, 93, 94, 95), azo pigments (CI pigment yellow 1, 3, 4,
5, 6, 65, 73, 97, 98, 74) nitro-based pigments such as Naphth-Ruiello-S, C.I. I. Solvent Yellow-14, C.I. I. Solvent Yellow-15, C.I. I.
Examples include dyes such as solvent yellow-16.

As the dispersion medium, it is preferable to use a non-polar, highly insulating carrier solvent such as hexane,
Octane, isoparaffin-based solvent Isopar E, G,
H, L, M (manufactured by Exxon), normal paraffinic solvent norpar 13 (manufactured by Exxon), Christol 5
2, liquid paraffin such as Cristol 70 and the like can be mentioned, but the invention is not limited thereto.

The average particle diameter of the toner particles contained in the liquid toner of the present invention is preferably 0.5 to 5 μm, more preferably 1 to 3 μm (the Shimadzu centrifugal sedimentation type particle size distribution measuring device SA-CP3 type is used. Measured using). If the particle size is too small, charge control becomes unstable and the white background tends to become defective. On the other hand, if the particle size is too large, the moving speed in the carrier solvent may slow down, and a sufficient developing concentration may not be obtained.

In the present invention, the content of the colorant in the toner particles is not particularly limited, but is usually about 0.5 to 5 parts by weight, preferably 1 to 3 parts by weight with respect to 10 parts by weight of the binder resin. . The content of the toner particles in the liquid toner of the present invention is not particularly limited, but is usually 0.5 to 10% by weight.
It is about 1 to 5% by weight, and preferably about 1 to 5% by weight.

The toner of the present invention is obtained by pulverizing a kneaded product containing at least a coloring agent such as a pigment or a dye and a fat or oil having an iodine value of 130 or more in a binder resin and dispersing the pulverized product in an insulating solvent. it can. In addition, at least the binder, a coloring agent such as a pigment or a dye, and an iodine value of 1
A kneaded product containing 30 or more fats and oils may be roughly pulverized, dispersed in an insulating solvent, and then pulverized by a suitable means together with the solvent until a desired particle size is obtained. In any case, the method for crushing is not particularly limited.

In the present invention, as an example of the method of kneading at least the binder resin, the colorant, and the oil having an iodine value of 130 or more, the binder resin, the colorant, and the iodine value of 1
A method of preliminarily mixing 30 or more fats and oils with a mixer and thermally kneading this mixture with a twin-screw extruder can be mentioned.
If necessary, a plasticizer, charge control agent, offset preventive agent, etc. (these are commonly used in this field)
You may add and knead.

As one method of crushing this kneaded material and dispersing it in a highly insulating solvent to form a liquid toner, first, the kneaded material is roughly crushed to a particle size of about 50 μm by a sample mill,
This is a method in which the coarse powder and a highly insulating solvent are mixed and pulverized by a vibration mill until a desired particle size of an average particle size of about 0.5 to 5 μm is reached. A ball mill or an attritor may be used instead of the vibration mill. Further, in this wet pulverization step, a charge control agent, wax, fine silica powder, etc. (these are commonly used in this field) may be added if necessary.

The toner of the present invention can be charged to both positively charged toner and negatively charged toner by appropriately selecting a charge control agent. In this case, any charge control agent conventionally used can be used. The content of the charge control agent in the toner particles is not particularly limited, but is usually about 0.1 to 2 parts by weight with respect to 10 parts by weight of the binder resin component.

The toner of the present invention is used to develop and visualize an electrostatic latent image on an electrostatic latent image bearing member. The electrostatic latent image bearing member may be, for example, an electrostatic recording medium. Examples include paper, selenium-based photoconductors, organic photoconductors, and amorphous silicon photoconductors. When a photoconductor is used as the electrostatic latent image carrier, the visualized image on the photoconductor developed by development is transferred and fixed on a support such as paper or film. Alternatively, electrostatically transfer the developed image on the photoconductor to the intermediate transfer body, and then retransfer the developed image on the intermediate transfer body onto a transfer material such as paper or film. The liquid toner of the present invention exerts a particularly excellent effect when used in this system.

In the image forming method of re-transferring the developed image on the intermediate transfer member onto the transfer material, the transferred material is brought into close contact with the intermediate transfer member with a pressure roller to re-image the transferred image on the transfer material. It is preferably used in an image forming method for transferring. The pressure roller used here has high heat resistance such as silicone rubber or fluororubber on the surface of the metal roller in order to enhance the adhesion with the metal roller or the intermediate transfer member. Rollers covered with rubber are preferably used.

Further, the pressure roller is preferably used in an image forming method in which the pressure roller is a heat roller including a heat source. As such a pressure roller, one having a cylindrical structure and containing a heat source such as a ceramic heater or a halogen lamp is preferably used.

[0025]

EXAMPLES The present invention will be described more specifically below based on Examples and Comparative Examples. However, the present invention is not limited to the following examples.

Method of Measuring Iodine Value In the following Examples and Comparative Examples, the iodine value is
It was measured as described in "Paint Handbook" (edited by Shinji Iwai, published by Sangyo Tosho in 1929), page 636.

Example 1 Rosin-modified maleic acid resin (Uniletz-709, acid value 110, softening point 120 ° C., manufactured by Union Camp) 14
00 g, carbon black (MOGUL-L, manufactured by Cabot) 400 g, polyethylene glycol (PEG6)
000, manufactured by Sanyo Kasei Co., Ltd.), and linseed oil (iodine value about 180, Wako Pure Chemicals Reagent 1st grade) 140 g were premixed with a mixer, and then melt-kneaded using a twin-screw extruder (feed amount 2 kg). / Hr, temperature 100 ° C). After the obtained melt-kneaded product is cooled, the particle size is about 50 using a sample mill.
It was a coarse powder of μm. 200 g of this coarse powder and 110 g of an acrylic polymer type charge control agent solution (US Pat. No. 3,900,
412, made by the method described in Example XI,
Solid content 14%), carnauba wax 15 g, isopa
M (isoparaffin solvent, 2 cp, exxon) 1
250 g was mixed and pulverized in a vibration mill for 5 hours to obtain a negatively charged liquid toner stock solution having an average particle size of about 1 μm. This stock solution was diluted with Isopa-M so that the solid content concentration was 2% to obtain a developer. Using this developer, double-sided printing was performed on a mirror-coated paper at a printing rate of 50% by a laser beam printer equipped with a heat fixing roller using an organic photoconductor. . In this laser beam printer, the electrostatic latent image on the electrostatic latent image carrier is developed with a liquid toner, and the developed image visualized by this development is electrostatically transferred to an intermediate transfer body. The image forming method of re-transferring the visible image on the intermediate transfer member onto the transfer material is adopted.

The printed matter thus obtained was allowed to stand at 25 ° C. for 2 days, then 1,000 sheets were piled up and left at 40 ° C. for one week, but no sticking or adhesion of the printed matter was observed. Further, the liquid toner stock solution could be easily redispersed even after being stored at 40 ° C. for one week.

Example 2 Using the developer prepared in the same manner as in Example 1, double-sided printing was carried out at a printing rate of 50% on a thermal transfer paper (smoothness TKP-50) in the same manner as in Example 1, and 25 After being left at 2 ° C for 2 days, 1000 sheets were piled up and left at 40 ° C for 1 week, but no sticking of the printed matter was observed.

Comparative Example 1 Rosin-modified maleic acid resin (Uniletz-709, acid value 110, softening point 120 ° C., manufactured by Union Camp Co.) 14
00g, Carbon Black (MOGUL-L) 400
g, polyethylene glycol (PEG6000, manufactured by Sanyo Kasei Co., Ltd.) 200 g were premixed 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 product, a sample mill was used to obtain a coarse powder having a particle size of about 50 μm. 200 g of this coarse powder and 110 g of an acrylic polymer type charge control agent solution (Example XI of US Pat. No. 3,900,412)
Produced by the method described in (14% solid content), 15 g of carnauba wax, and 1250 g of Isopa-H (isoparaffinic solvent, 1 cp, exxon),
The toner was pulverized for 6 hours with a vibration mill to obtain a negatively charged liquid toner stock solution having an average particle size of about 1 μm. This stock solution has a solid content of 2%
Was diluted with Isopar-H to obtain a developer. When this developer was used and evaluated in the same manner as in Example 1, a part of the printed matter was stuck and adhered.

Comparative Example 2 Rosin-modified maleic acid resin (Uniletz-709, acid value 110, softening point 120 ° C., manufactured by Union Camp) 14
00g, Carbon Black (MOGUL-L) 400
g, polyethylene glycol (PEG6000, manufactured by Sanyo Kasei Co., Ltd.) 160 g, and linseed oil (iodine value about 180, Wako Pure Chemicals reagent first grade) 40 g were premixed 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 product, a sample mill was used to obtain a coarse powder having a particle size of about 50 μm. 200 g of this coarse powder and 110 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)
%), Carnauba wax 15 g, ISOPA-M1250
g and pulverized in a vibration mill for 5 hours to obtain a negatively charged liquid toner stock solution having an average particle size of about 1 μm. This stock solution was diluted with Isopa-M so that the solid content concentration was 2% to obtain a developer. When this developer was used and evaluated in the same manner as in Example 1, a part of the printed matter was stuck and adhered.

Comparative Example 3 Rosin-modified maleic acid resin (Uniletz-709, acid value 110, softening point 120 ° C., manufactured by Union Camp) 11
00g, Carbon Black (MOGUL-L) 200
g and 700 g of eno oil (iodine value of about 200) were premixed 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 product, a particle size of about 5 is obtained using a sample mill.
It was a coarse powder of 0 μm. 200 g of this coarse powder, 7 g of cobalt naphthenate, 15 g of carnauba wax, Isopar-H
1250g was mixed and crushed with a vibration mill for 5 hours,
A positively charged liquid toner stock solution having an average particle size of about 1 μm was obtained.

When this liquid toner stock solution was stored at 40 ° C. for one week, a coagulated product was produced and redispersion was difficult.

Comparative Example 4 The same evaluation as in Example 1 was carried out using a toner prepared in exactly the same manner as in Example 1 except that cottonseed oil (iodine value of about 120) was used instead of linseed oil. , The prints stuck to each other, and part of the paper was damaged when peeled off.

Example 3 Frosin-modified fumaric acid resin (Unilet's 8112, acid value 1
15, softening point 130 ℃, made by Union Camp) 160
0 g, carbon black (MOGUL-L) 200 g,
100 g of polyethylene glycol (PEG6000, manufactured by Sanyo Kasei Co., Ltd.) and 100 g of linseed oil (iodine value of about 180, Wako Pure Chemicals reagent first grade) were premixed with a mixer, and then melt-kneaded using a twin-screw extruder ( Feed rate 3kg / h
r, temperature 120 ° C). After cooling the obtained melt-kneaded product, a sample mill was used to obtain a coarse powder having a particle size of about 50 μm. 200 g of this coarse powder and 110 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)
%), Carnauba wax 15 g, ISOPA-M1250
g and pulverized with a vibration mill for 3 hours to obtain a negatively charged liquid toner stock solution having an average particle size of about 2 μm. This stock solution was diluted with Isopa-M so that the solid content concentration was 2% to obtain a developer.

When the same test as in Example 2 was conducted using this developer, no sticking or sticking of the printed matter was observed. Further, the liquid toner stock solution could be easily redispersed even after being stored at 40 ° C. for one week.

Example 4 Frosin-modified fumaric acid resin (Uniletz 8112, acid value 1
15, softening point 130 ℃, manufactured by Union Camp) 120
0 g, C.I. I. Pigment 122 quinacridone magenta pigment 200g, tung oil (iodine value about 190) 600g
Was pre-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 product, a sample mill was used to obtain a coarse powder having a particle size of about 50 μm. This coarse powder 20
0g and 110g of acrylic polymer charge control agent solution
(Manufactured by the method described in Example XI of US Pat. No. 3,900,412, solid content: 14%), carnauba wax (15 g), and Isopa-G (isoparaffin solvent, manufactured by Exxon) 1250 g are mixed, The toner was pulverized for 3 hours with a vibration mill to obtain a negatively charged liquid toner stock solution having an average particle size of about 2 μm. This stock solution was diluted with Isopar-G to a solid content concentration of 2% to obtain a developer.

When the same test as in Example 2 was conducted using this developer, no sticking or sticking of the printed matter was observed. Moreover, the liquid toner stock solution could be easily redispersed even after being stored at 40 ° C. for 3 days.

[0039]

As described above, the liquid toner of the present invention is used.
Is a liquid toner suitable for use in the field of small-lot printing and the like, because printed matter does not adhere to each other, has excellent stackability, and has excellent storage stability.

Claims (3)

[Claims] 1. A liquid toner for developing an electrostatic latent image, comprising toner particles containing at least a binder resin and a colorant dispersed in a dispersion medium, wherein the toner particles are contained in 100 parts by weight of the binder resin component. On the other hand, an electrostatic latent image developing liquid toner containing 5 to 50 parts by weight of an oil or fat having an iodine value of 130 or more. 2. The liquid toner for developing an electrostatic latent image according to claim 1, wherein the binder resin contains a rosin-modified resin. 3. An electrostatic latent image on an electrostatic latent image carrier is developed with a liquid toner, the developed image visualized by this development is electrostatically transferred to an intermediate transfer body, and then the intermediate transfer is carried out. The liquid toner for developing an electrostatic latent image according to claim 1, which is used in an image forming method for retransferring a visible image on a body onto a transfer material.