KR100560713B1 - Liquid toner composition for electrophotography and recording medium using the same - Google Patents

Abstract

The present invention relates to an electrophotographic liquid toner and a recording medium using the same, comprising: carbon black having an average particle diameter of 20 to 35 nm, a DBP oil absorption of 30 to 90 ml / 100 g, and a surface area of 100 m 2 / g or less; Organosol; And by providing a liquid electrostatic toner composition for electrophotographic, characterized in that it comprises a charge control agent, it is possible to provide a recording medium having excellent transfer characteristics by having excellent mobility characteristics due to electrostatic attraction.

Electronic photography, liquid toner, laser transfer

Description

LIQUID TONER COMPOSITION FOR ELECTROPHOTOGRAPHY AND RECORDING MEDIUM USING THE SAME}

1A and 1B are diagrams showing that a black liquid toner moves by a voltage difference in a state where electric charge is applied to test the mobility of the electrophotographic liquid toner.

The present invention relates to an electrophotographic liquid toner and a recording medium using the same. More particularly, the present invention relates to an electrophotographic liquid toner and an recording medium using the same.

In general, the electrophotographic method forms an electric latent image on a photoconductor composed of a photoconductor material such as selenium, zinc oxide, cadmium sulfide, etc., develops it into a powder phosphor, transfers it to paper, and fixes it.

The electrophotographic method includes a dry type electrophotographic printing method and a wet type electrophotographic printing method.

Among them, the wet electrophotographic method has the same resolution as the photograph, and in the wet electrophotographic method, image development can be formed by using a liquid toner.

The liquid toner first contains an electrically insulating liquid and a pigment, which is a fine particle dispersed in the liquid.

That is, the liquid toner is an electrically insulating carrier liquid having an electrical resistance of 10 ⁹ to 10 ¹⁵ μs / cm, color embodying fine particles dispersed in the carrier liquid, an electrically insulating carrier liquid soluble resin, and a color. It includes a charge control agent for charging the embodiment particles to + or-.

Conventionally, carbon black and various non-blackbody pigments have been used as the fine particle pigments. On the other hand, the resin was used to disperse or fix the color realizing particles.

On the other hand, particle size, dibutyl phthalate (DBP) oil absorption amount, surface area, etc. are used to show the characteristics of the carbon black pigment according to the particle size and the degree of development of the structure. The above characteristic values are different and their use is different accordingly.

Therefore, even carbon black pigments have different characteristics due to the different degree of development of particle size and structure depending on the product group and grade name, which may affect the electrical properties and image quality of carbon black pigments. It is expected.

U.S. Patent 6,087,434 discloses an electrophotographic liquid toner, and the patent discloses carbon black having a specific average particle diameter, DBP oil absorption, surface area, and pH range, and is used for a positive charging liquid toner. In addition, the patent allows to fix the pigment using a common resin (resin).

In such a transfer photographing method, the characteristics of the carbon black pigment that can be used according to the charge control agent, the resin, etc. which are added together with the carbon black pigment are changed, thereby changing the characteristics of the liquid toner for electrophotography.

Therefore, in order for an electrophotographic liquid toner to have suitable electrical properties and thereby exhibit excellent image quality, it is necessary to use a carbon black pigment having the most suitable characteristic value.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a liquid toner composition and a recording medium using the same, in which the electrical properties of the liquid toner used in the electrophotographic are optimized to achieve the best image quality.

In order to achieve the above technical problem, the present invention provides a carbon black having an average particle diameter of 20 to 35 nm, a DBP oil absorption of 30 to 90 ml / 100 g, and a surface area of 100 m 2 / g or less; Organosol; And it provides an electrophotographic liquid toner composition comprising a charge control agent.

The present invention also provides a carbon black having an average particle diameter of 20 to 35 nm, a dibutyl phthalate (DBP) oil absorption of 30 to 90 ml / 100 g, and a surface area of 100 m 2 / g or less; Organosol; And milling at room temperature after the charge control agent is added together to provide a method for producing an electrophotographic liquid toner composition.

The present invention also provides a recording medium such as a laser printer or copier using the liquid toner composition.

Hereinafter, the present invention will be described in detail.

1A and 1B show the movement of the black liquid toner by the voltage difference in the state where electric charge is applied to test the mobility of the electrophotographic liquid toner composition.

First, in FIG. 1A, a black liquid toner is operated because a voltage of + 400 V is applied to the development roll 20, so that about 400 V or more is higher than an operating belt 10. All will be laid in (10).

On the other hand, in FIG. 1B, since the voltage of the development roll 20 is -400 V lower than that of the operation belt 10, the black liquid toner moves to the development roll 20 and no ink remains in the operation belt.

Therefore, in order for the ink to move from the toner cartridge to the paper, the value of the optical density OD of the operation belt must be different. That is, the optical density 40 of the area where the ink is printed should be large, and the optical density (background OD) 50 of the non-image area where the ink is not printed should be small.

That is, considering that the toner is moved from the toner cartridge to the paper by the electrostatic attraction due to the voltage difference in the recording medium, the conditions as the liquid toner should be excellent in charging characteristics, and if the toner can be used in the recording medium, Figs. Even if the operation of FIG. 1B is repeated several times, all toner particles must be able to move back and forth between the developer roll and the actuation belt.

In the present invention, carbon black having an average particle diameter of 20 to 35 nm, a dibutyl phthalate (DBP) oil absorption of 30 to 90 ml / 100 g, and a surface area of 100 m 2 / g or less in order to optimize the electrical properties as described above; Organosol; And it provides an electrophotographic liquid toner comprising a charge control agent.

If the average particle diameter of the carbon black is 20 nm or less or 35 nm or more, the particles of the wet toner made using the carbon black do not have proper positive charge (+) characteristics, and thus the toner mobility due to electrostatic attraction becomes very poor. Not desirable

In addition, the dibutyl phthalate oil absorption of the carbon black is a factor that greatly affects the mobility of the ink. If the amount of the liquid toner is 30 ml / 100 g or less or 90 ml / 100 g or more, the toner particles do not have proper positive charge (+) characteristics. It is not preferable because the toner mobility due to electrostatic attraction becomes very poor.

In addition, when the surface area of the carbon black is 100 m 2 / g or more, the particles of the liquid toner do not have proper positive charge (+) characteristics, so that the optical density of the non-image area is increased and the ink mobility due to electrostatic attraction is increased. It is not desirable because it will fall out.

On the other hand, the pH indicates the acid and basicity of the toner, but the influence on the toner mobility due to electrostatic attraction is considered to be insignificant, but since it affects the mobility to some extent, it is preferably between 2 and 10.

The electrophotographic liquid toner composition of the present invention also contains an organosol and a charge control agent as well as carbon black.

Organosols serve as binders and dispersion agents of colorants and charge control agents.

Organosols include graft copolymers comprising a (co) polymer steric stabilizer covalently bonded to a thermoplastic (co) polymer core insoluble in a carrier liquid, wherein the thermoplastic (co) polymer core has an aliphatic amino radical (meth) At least one polymerizable monomer selected from the group consisting of an acrylate monomer, a nitrogen-containing heterocyclic vinyl monomer, an N-vinyl substituted ring-like amide monomer, an aromatic substituted ethylene monomer comprising an amino radical, and a nitrogen-containing vinyl ether monomer It is preferable to include units derived from.

The graft stabilizer includes a repeating unit derived from a (meth) acrylic monomer having 6 to 30 carbon atoms. The said C6-C30 (meth) acrylic-type monomer is hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 2-hydroxyethyl methacrylate, decyl (meth) acrylate, and dodecyl acrylate. , Lauryl acrylate, octadecyl acrylate, stearyl acrylate, (biphenyl) acrylate, trimethyl cyclohexyl methacrylate, and the like.

The thermoplastic (co) polymer core includes a repeating unit derived from a (meth) acrylic monomer having 4 to 30 carbon atoms. Wherein the (meth) acrylic monomer having 4 to 30 carbon atoms is methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, trimethyl cyclohexyl methacrylate, octadecyl It is preferably at least one selected from the group consisting of acrylate, biphenyl acrylate and the like.

The organosol is used in 1 to 10 parts by weight based on 1 part by weight of the carbon black, the charge control agent is used in 0.001 to 1 parts by weight, more preferably the organosol comprises 5 to 8 parts by weight, It is preferable to use 0.01-0.1 weight part of charge control agents.

Non-limiting examples of such carrier fluids include aliphatic hydrocarbons (n-pentane, hexane, heptane, etc.), alicyclic hydrocarbons (cyclopentane, cyclohexane, etc.), aromatic hydrocarbons (benzene, toluene, xylene, etc.), halogenated hydrocarbon solvents. (Chlorinated alkanes, fluorinated alkanes, chlorofluorocarbons, etc.), silicone oils, and mixtures thereof. Carrier fluids include, in particular, trade names Isopar G, Isopar H, Isopar K, Isopar L, Isopar M, Isopar V (Exxon Corporation), and Norpar 12 (Exxon Corporation). Preferred is a branched paraffin solvent mixture such as Norpar 15 (Exxon Corporation).

In addition, a charge control agent (CCA) is a method of chemically reacting a charge control agent with developer particles by imparting charge characteristics to toner particles, and a method in which developer particles adsorb the charge control agent chemically or physically. Alternatively, the charge control agent is introduced into the developer particles by various methods such as the method of chelating the functional groups introduced into the toner particles. The charge control agent serves to impart a predetermined polarity charge on the developer particles, and any charge control agent known in the art can be used.

For example, the charge control agent may be introduced in the form of a metal salt composed of polyvalent metal ions and organic anions as counter ions. Examples of such metal ions include Ba (II), Ca (II), Mn (II), Zn (II), Cu (II), Al (III), Cr (III), Fe (II), Fe ( III), Sb (III), Bi (III), Co (II), La (III), Pb (II), Mg (II), Mo (III), Ni (II), Ag (I), Sr ( II), Sn (IV), V (V), Y (III), Ti (IV) and the like are suitable. Organic anions include carboxylates or sulfonates derived from aliphatic or aromatic carboxylic acids or sulfonic acids. Among them, zirconium-2-ethylhexanoate is preferably used to impart (+) charge to the liquid toner particles.

A method of manufacturing an electrophotographic liquid toner having the composition as described above is as follows.

First, LMA-EMA organosol with 18% solids content, carbon black, and Norpar 12 as a carrier fluid are added.Then, the charging agent is applied so that the wet black toner has an appropriate charge to mass ratio (Q / M) according to the carbon black type. Yesterday (solid content 2.4%) and Zr beads. The electrophotographic liquid toner of the present invention is produced by milling at a milling speed of 4,500 rpm and a milling temperature of 42 ° C. for 3 hours and then collecting the same.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited only to the following Examples.

Examples 1-6

71.4 g of LMA-EMA organosol with 18% solids content, 1.6 g of carbon black, and 26 g of Norpar12 as a carrier fluid were used, followed by Q / M. 1.5-3.0 g of a charge control agent (solid content 2.4%) and 200 g of Zr beads were added thereto. The electrophotographic liquid toner of the present invention was produced by milling at a milling speed of 4500 rpm and a milling temperature of 42 ° C. for 3 hours and then collecting the same. Carbon black of Example 1 is Special Black 350 (manufactured by Degussa), Example 2 is Nipex35 (manufactured by Degussa), Example 3 is Raven 1080 (manufactured by Columbia), Example 4 is Raven860 (manufactured by Columbia), Example 5 used Regal 1500R (made by Cabot), and Example 6 used EK8200 (made by Aztech).

Comparative Examples 1 to 4

A liquid toner for electrophotography was prepared in the same manner as in Example 1 except that the carbon black shown in Table 1 was used instead of the carbon black used in Example 1.

In Comparative Example 1, Nipex150 (manufactured by Degussa), Nipex70 (manufactured by Degussa), Comparative Example 3, Raven1040 (manufactured by Columbia), and Monarch1400 (manufactured by Cabot) were used as carbon black.

Relationship between pH, DBP oil absorption, surface area, particle size and optical density of the image area, optical density and non-image area of the electrostatic liquid toner of Examples 1 to 6 and Comparative Examples 1 to 4 described above Is shown in Table 1.

pH DBP oil absorption Surface area (㎡ / g) Particle size (nm) Optical density of printing area Optical density in non-image areas Mobility Example 1 3.5 45 65 31 1.90 0.02 Great Example 2 9 42 65 31 1.81 0.02 Great Example 3 3-3.5 60 77 28 1.88 0.01 Great Example 4 3-3.5 50 48 39 1.85 0.01 Great Example 5 7.0-9.0 65 86 25 1,71 0.01 Great Example 6 3 56 - - 1.91 0.01 Great Comparative Example 1 4 122 110 25 1.71 0.04 Bad Comparative Example 2 9 123 145 18 1.54 1.51 Bad Comparative Example 3 6.5-8 100 82 28 1.81 0.40 Bad Comparative Example 4 1.5-3.5 90 560 13 1.17 0.92 Bad

As can be seen from Table 1, when the DBP oil absorption is 90 or less, the surface area is 100 or less, and the particle size is between 20 and 35 nm, the optical density of the print area is 1.71 to 1.91, and the optical of the non-image area It can be seen that the density is 0.01 to 0.02.

On the contrary, in the case of Comparative Examples 1 to 4, first, the DBP oil absorption amount is 90 or more, which is larger than any of Examples 1 to 6, except that Comparative Example 3 has a surface area of 100 or more than that of Examples 1 to 6. It is very large. Accordingly, looking at the mobility of the liquid toner, it can be seen that the case of Examples 1 to 6 is superior to that of Comparative Examples 1 to 4. This means that the mobility of the electrostatic attraction is excellent in Examples 1 to 6.

On the other hand, when looking at the particle size, it can be seen that in the case of Examples 1 to 6 is 25 to 39 nm larger than the comparative example, in the case of Comparative Examples 1 and 3 it can be seen that the particle size is 25 and 28 nm but Looking at the mobility it can be seen that the mobility is not good.

Therefore, the carbon black capable of satisfying the charging characteristics in the present invention is not said to satisfy only one of the above conditions, but for electrophotographic having excellent electrostatic charging characteristics when all three requirements of oil absorption amount, particle size and surface area are satisfied. The liquid toner composition can be prepared.

Therefore, the electrophotographic liquid toner of the present invention can be used for a recording medium such as an electrophotographic transfer apparatus, and the electrophotographic transfer apparatus may be a laser printer or a copier.

As described above, when the liquid toner is manufactured using carbon black that satisfies three conditions of oil absorption, particle size and surface area as in the present invention, it is used in an electrophotographic transfer apparatus due to its excellent mobility due to electrostatic attraction. Can provide excellent liquid toner.

Claims (12)

Carbon black having an average particle diameter of 20 to 35 nm, dibutyl phthalate (DBP) oil absorption of 30 to 90 ml / 100 g, and a surface area of 100 m 2 / g or less; An electrophotographic liquid toner composition comprising an organosol and a charge control agent. The method of claim 1, The organosol is 1 to 10 parts by weight and the charge control agent is 0.001 to 1 part by weight based on 1 part by weight of the carbon black. The method of claim 2, The organosol comprises 5 to 8 parts by weight and the charge control agent comprises 0.01 to 0.1 parts by weight based on 1 part by weight of the carbon black. The method of claim 1, The charge control agent is in the form of a metal salt composed of a polyvalent metal ion and an organic anion as a counter ion, and the metal ion is Ba (II), Ca (II), Mn (II), Zn (II), Cu (II), Al (III), Cr (III), Fe (II), Fe (III), Sb (III), Bi (III), Co (II), La (III), Pb (II), Mg (II), Mo One kind of metal selected from the group consisting of (III), Ni (II), Ag (I), Sr (II), Sn (IV), V (V), Y (III), and Ti (IV); Wherein the organic anion is a carboxylate or sulfonate derived from an aliphatic, aromatic carboxylic acid or sulfonic acid. The method of claim 4, wherein The charge control agent is zirconium-2-ethylhexanoate (zirconium-2-ethylhexanoate) liquid electrophotographic toner composition. The method of claim 1, The carbon black has a pH of 2 to 10 electrophotographic liquid toner composition. The method of claim 1, The organosol includes a graft copolymer comprising a (co) polymer steric stabilizer covalently bonded to a thermoplastic (co) polymer core that is insoluble in a carrier liquid, wherein the graft copolymer comprises (meth) of 6 to 30 carbon atoms (Meth) acrylic monomers including repeating units derived from acrylic monomers include hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 2-hydroxyethyl methacrylate, decyl (meth) acrylate, At least one selected from the group consisting of dodecyl acrylate, lauryl acrylate, octadecyl acrylate, stearyl acrylate, (biphenyl) acrylate, trimethyl cyclohexyl methacrylate, and the like, and the thermoplastic (co) polymer core Is a (meth) acrylic system containing a repeating unit derived from a (meth) acrylic monomer having 4 to 30 carbon atoms The monomer is selected from the group consisting of methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, trimethyl cyclohexyl methacrylate, octadecyl acrylate, biphenyl acrylate One or more electrophotographic liquid toner compositions. Carbon black having an average particle diameter of 20 to 35 nm, dibutyl phthalate (DBP) oil absorption of 30 to 90 ml / 100 g, and a surface area of 100 m 2 / g or less; Organosol; And milling at room temperature after the charge control agent is added together. The method of claim 8, The organosol is 1 to 10 parts by weight and the charge control agent is 0.001 to 1 part by weight based on 1 part by weight of the carbon black. The method of claim 9, The organosol comprises 5 to 8 parts by weight and the charge control agent comprises 0.01 to 0.1 parts by weight based on 1 part by weight of the carbon black. A recording medium using the liquid toner composition of claim 1. The method of claim 11, And the recording medium is a laser printer or a copying machine.

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