KR100661353B1 - Preparation method of toner composition - Google Patents

Abstract

A method of making a liquid toner composition is disclosed. The method for preparing the liquid toner composition comprises mixing and polymerizing a graft stabilizer-forming monomer and a first polymerization initiator in a first carrier liquid to prepare a graft stabilizer; Preparing a organosol by mixing and polymerizing the prepared graft stabilizer, a thermoplastic (co) polymer core forming monomer, and a second polymerization initiator to a second carrier liquid; And milling the prepared organosol, colorant and charge control agent at a high temperature in a third carrier liquid to prepare a toner composition. According to the present invention, it is possible to produce a liquid toner composition which can improve the dispersion stability without impairing the physical properties of the liquid toner itself, and also has the effect of improving the mass productivity by lowering the manufacturing cost and simplifying the manufacturing process.

Organosol, Toner, Dispersible

Description

Preparation method of liquid toner composition {Preparation method of toner composition}

The present invention relates to a method for producing a liquid toner composition. More specifically, by preparing a liquid toner using an organosol having a volume average particle size of less than or equal to micrometer, the dispersibility of the toner composition is improved, so that the dispersibility can be maintained even during long-term storage and the manufacturing process of the liquid toner composition is simple. It's about how.

The toner composition is used as a developer in electrophotographic image forming apparatuses such as copiers, laser printers, fax machines and the like.

The electrophotographic image forming apparatus operates to move the toner particles by electric force to print a desired image on the recording medium. The electrophotographic image forming apparatus may be classified into a dry electrophotographic image forming apparatus using a dry toner and a wet electrophotographic image forming apparatus using a liquid toner (or liquid toner) according to the toner used.

Since liquid toner uses smaller toner particles than dry toners, it is possible to achieve relatively high resolution, to print at a high speed, and to use a relatively small amount of toner.

A liquid toner is a structure in which toner particles are dispersed on a liquid carrier, and are generally charged with a toner particle composed of a polymer resin, which is a colorant and a binder, and a charge control agent for controlling the amount of charge charged to the toner particles, and a charge control with the toner particles. It consists of a carrier liquid in which I am dispersed. In addition, an additive for improving the functionality of the toner may be further included.

The liquid toner used in the wet electrophotographic image forming apparatus can be classified into two types according to the binder resin used in the toner. There are a liquid toner using a common commercial resin and an organosol liquid toner using an organosol.

Organosol liquid toner has a merit of achieving a high resolution image because the toner particles have a diameter of several micrometers and are charged stably.

Conventionally, a method for preparing an organosol liquid toner includes a graft stabilizer and a core monomer containing a grafting functional group, and a small amount of a polymerization initiator, together with a carrier liquid, stirred at room temperature, and then raised to a polymerization temperature, thereby free radicals. A stripping process was carried out in order to carry out the polymerization reaction by the reaction and to remove unreacted monomers.

Thus, finally, a core-shell structured organosol having a volume average particle size of 20 μm to 30 μm was prepared. This organosol was then dispersed together with a colorant and a charge control agent to prepare a liquid toner composition having a volume average particle size of 1 to 5 mu m.

The conventional method for preparing the liquid toner composition is to prepare an organosol having a volume average particle size of 20 μm to 30 μm into a liquid toner having a volume average particle size of 3 μm to 5 μm through milling.

However, the stripping process performed in organosol production uses expensive equipment, and the process itself has a complicated difficulty. In addition, the final liquid toner prepared by the method of making an organosol having an average particle size of 20 μm to 30 μm into a toner having a size of 3 μm to 5 μm through milling does not have the graft stabilizer uniformly distributed on the toner particle surface. In the state, thereby reducing the dispersibility and storage stability of the toner particles. These liquid toners are agglomerated over long periods of time or undergo harsh conditions, which makes it difficult to disperse even simple shaking during reuse, making it difficult to use.

The present invention has been made to solve the above problems, and an object of the present invention is to maintain long-term dispersion stability of the toner without impairing the properties of the toner itself, and to simplify the manufacturing process, It is an object of the present invention to provide a method for producing a liquid toner that can reduce cost.

Method for producing a liquid toner composition according to the present invention for achieving the above object comprises the steps of preparing a graft stabilizer by mixing and polymerizing the graft stabilizer forming monomer and the first polymerization initiator in the first carrier liquid;

Preparing a organosol by mixing and polymerizing the prepared graft stabilizer, a thermoplastic (co) polymer core forming monomer, and a second polymerization initiator to a second carrier liquid; And

And milling the prepared organosol, colorant and charge control agent at a high temperature into a third carrier liquid to prepare a toner composition.

In the preparing of the organosol, the content of the second polymerization initiator is preferably within the range of 0.15 to 0.3 parts by weight based on 1 part by weight of the monomer for forming the thermoplastic (co) polymer core.

The volume average particle size of the prepared organosol is preferably within the range of 0.1 ㎛ to 1.0 ㎛.

In the step of preparing the toner composition, the temperature at the time of milling is preferably within the range of 90 ℃ to 180 ℃.

The volume average particle size of the prepared toner particles is preferably in the range of 1 µm to 5 µm.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples according to the present invention.

In order to prepare the liquid toner composition according to the present invention, a graft stabilizer is prepared by first mixing and polymerizing a graft stabilizer-forming monomer and a polymerization initiator in a carrier liquid. Then, the graft stabilizer prepared in the carrier liquid, a monomer for forming a thermoplastic (co) polymer core, and a polymerization initiator are mixed and polymerized to prepare an organosol having a volume average particle size within the range of 0.1 µm to 1.0 µm.

Graft stabilizer monomer for forming is preferably a (meth) acrylic monomer of the C ₆ to C _30. For example, alkyl acrylates, alkyl methacrylates, ethylene, propylene, acrylamide, aryl acrylates, aryl methacrylates, high molecular weight alphaolefins, straight or branched alkyl vinyl ethers or vinyl esters, Long-chain alkyl isocyanates, polysiloxanes and polysilanes, and polymerizable synthetic waxes and the like, but are not limited thereto. One or two or more kinds of the above-mentioned monomers can be selected and mixed.

The core for core formation is preferably a C ₄ to C ₃₀ (meth) acrylic monomer. For example, methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, trimethyl cyclohexyl methacrylate, behenyl acrylate, octadecyl acrylate, and the like. One or two or more kinds of these monomers may be used in combination. However, the monomer which can be used is not limited to this.

Carrier liquids that can be used to prepare graft stabilizers and organosols are aliphatic hydrocarbons, cyclic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbon solvents, silicone oils and waxes, polyethylene waxes, stearic acid waxes, stearic acid amides or these And the like, but are not limited thereto.

Polymerization initiators that can be used in the preparation of the graft stabilizer and the organosol include, but are not limited to, water-soluble or fat-soluble persulfates, peroxides and azobis compounds. Any one of the compounds described above may be selected and used alone or in combination of two or more thereof.

The content of the polymerization initiator used in the preparation of the organosol is preferably in the range of 0.15 parts by weight to 0.3 parts by weight with respect to 1 part by weight of the monomer for forming a thermoplastic (co) polymer core.

The content of the polymerization initiator used in the method for producing the organosol of the present invention is 2 to 3 times or more than the content of the polymerization initiator used in the general method for preparing the organosol. As the content of the polymerization initiator is increased, the volume average particle diameter of the prepared organosol becomes small, and thus, a toner composition having improved dispersion stability can be prepared as intended in the present invention.

The content of the polymerization initiator described above is the value given in the experimental values.

According to the conventional method for preparing the organosol toner, stripping is performed as a final step in the preparation of the organosol. Stripping is the process of removing residual monomer that remains unreacted in order to adjust the volume average particle size when preparing the toner. Stripping increases the volume average particle size of the organosol.

The stripping process itself is quite complicated and difficult to remove unreacted residual monomers while maintaining a constant temperature under vacuum conditions.

In the present invention, the conventional stripping process can be omitted because milling is performed at high temperature during the preparation of the liquid toner after the preparation of the organosol.

The volume average particle size of the organosol thus prepared is within the range of 0.1 μm to 1.0 μm. When the toner composition is prepared using the organosol, the graft stabilizer is uniformly distributed on the surface of the toner particles, thereby improving the grafting efficiency. In addition, the graft stabilizer can also play a role as a stabilizer, thereby suppressing the tendency for the toner particles to aggregate together. Therefore, the toner composition produced by the production method of the present invention can improve dispersibility and maintain its dispersibility even during long term storage.

The preparation of the final toner composition is carried out by milling the organosol, colorant and charge control agent in a carrier liquid at high temperature.

Carrier liquids used in this step are, for example, aliphatic hydrocarbons such as n-pentane, hexane and heptane, cyclic hydrocarbons such as cyclopentane and cyclohexane, aromatic hydrocarbons such as benzene, toluene and xylene, chlorinated alkanes and fluorinated Halogenated hydrocarbon solvents such as alkanes and chlorofluorocarbons, silicone oils and waxes, polyethylene waxes, branched paraffinic waxes and oils, stearic acid amides, and the like, but are not limited thereto. The above-mentioned carrier liquid can be used individually or in mixture of 2 or more types. Examples of commercially available carrier liquids include Isopar G, Isopar H, Isopar K, Isopar L, Isopar M, Isopar V, and Nopa 12 from Exxon Corporation. (Norpar 12), old woman 15, and so on.

The content of the carrier liquid in the liquid toner composition is preferably within the range of 10 parts by weight to 100 parts by weight with respect to 1 part by weight of the colorant. If the content of the carrier liquid is less than 10 parts by weight, the content of the toner particles is relatively increased, so that the viscosity of the liquid toner is high, which makes it difficult to control the liquid toner and causes an image to be printed even in the non-image area. In addition, if the content is greater than 100 parts by weight, the content of the colorant is relatively low, so that the concentration of the colorant is low, so that the OD of the image area of the printed image is low, and the liquid toner is easily consumed, and frequent replacement is inevitable.

Although the coloring agent of a toner composition can use either a dye type coloring agent or a pigment type coloring agent, It is preferable to use the pigment type coloring agent which shows the outstanding thing in thermal stability or light resistance.

Examples of the pigment colorant that can be used in the present invention include azo pigments, phthalocyanine pigments, basic dye pigments, quinatridone pigments, dioxacin pigments, condensed azo pigments, chromates, ferrocyanides, and oxides. And sulfide selenides, sulfates, silicates, carbonates, phosphates, metal powders, carbon blacks, and the like, and these pigments may be used singly or in combination of two or more, but the pigments that can be used are not limited thereto.

The color pigments that can be used as the pigment of the toner composition according to the present invention are classified by color as follows.

Blue and / or green pigments include copper phthalocyanine, Pigment Blue (PB) 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 16 free metal phthalocyanine, and aluminum as the center metal. Phthalocyanine with nickel or vanadium, bridged phthalocyanine dimers / oligomers such as Si-bridged phthalocyanine and the like.

Orange pigments include P.O. (Pigment Orange) 5, 13, 43, 71, 72 and the like.

Yellow pigments include P.Y. (Pigment Yellow) 12, 13, 17, 74, 83, 93, 146, 156, 180, 185 and the like.

Red pigments include P.R. (Pigment Red) 48, 57, 122, 146, 147, 176, 184, 186, 202, 207, 238, 254, 255, 269, 270, 272 and the like.

Mixed pigments include P.V.19 / P.R.122 or P.R.146 / 147.

The pigments described above may be used in the preparation of the liquid toner composition according to the present invention, but are not limited thereto.

In the preparation of the liquid toner composition according to the present invention, the content of the organosol is preferably within the range of 10 parts by weight to 50 parts by weight with respect to 1 part by weight of the colorant. The organosol simultaneously functions as a binder and a dispersant in the liquid toner. If the content of organosol is less than 10 parts by weight, it is difficult to expect a function as a dispersant. In addition, when the content of the organosol is more than 50 parts by weight, the content of the colorant is relatively small, which causes a problem that the sharpness of the printed image is lowered.

A charge control agent is added to control the amount of charge charged to the toner particles.

The charge control agent may bind to the toner particles through various methods such as chemically reacting with the toner particles or chemically, physically adsorbing, or chelate-forming the specific functional groups of the toner particles.

In the preparation of the liquid toner composition according to the present invention, any charge control agent known in the art may be used. For example, fatty acid metal salts, sulfo-succinate metal salts, alkyl-benzenesulfonate metal salts, aromatic carboxylic acid metal salts, sulfonic acid metal salts, polyoxyethylated alkylamines, lecithins, polyvinylpyrrolidones, basic barium petronates and calcium Petronate and the like, but are not limited thereto. Commercially available charge control agents include Zirconium Chemical's zirconium HEX-CEM from Cleveland, Ohio.

The content of the charge control agent in the preparation of the liquid toner composition according to the present invention is preferably within the range of 0.001 to 1 part by weight based on 1 part by weight of the colorant. When the content of the charge control agent is out of this range, it becomes difficult to control the charge amount charged to the toner particles. Therefore, it is difficult to obtain a clear image because the OD of the image region is lowered without obtaining a desired image.

The toner composition is prepared by dispersing a colorant and a charge control agent in an organosol, placing the components in a milling vessel, and then milling the components at a high temperature at a constant speed to uniformly disperse the components on the carrier while physically bonding the components. do.

In the process of preparing the toner composition, the temperature at the time of milling is preferably within 90 ° C to 180 ° C. The milling temperature is one in which the temperature naturally rises due to the frictional force generated by milling during the manufacturing process of the toner composition.

By making the milling temperature high, it is possible to remove the unreacted monomers remaining in organosol preparation, thereby exhibiting the effects of the conventional stripping process. In addition, the particle size distribution of the components of the toner composition can be evened by the milling process.

The milling temperature is preferably determined in consideration of the melting temperature of the constituents. In particular, a hydrocarbon material is mainly used as the carrier liquid of the liquid toner composition, and the milling temperature is preferably such that it is below the boiling point of the hydrocarbon material used as the carrier liquid.

The adjustment of the milling temperature can be controlled by controlling the stirring speed during milling or by adjusting the amount of beads added together for milling.

Conventionally, in the preparation of organosol, the remaining monomers are removed by stripping, which is a complicated and difficult process. According to the present invention, the remaining monomers may be removed by milling under high temperature conditions in the process of preparing the toner composition, and at the same time, the volume of the toner particles There is an advantage to control the average particle size.

The volume average particle size of the toner particles of the toner composition thus prepared is within the range of 1 µm to 5 µm. The smaller the volume average particle size of the toner particles is, the higher the resolution can be achieved. However, if the volume average particle size is smaller than 1 µm, the volume average of the toner particles may be a problem during the transfer or fixing step in the environment where the current toner composition is used. The particle size is preferably within the range of 1 μm to 5 μm.

The preparation of the toner composition according to the present invention can be simpler and lower in cost compared to the conventional process, and by preparing the toner composition by milling at a high temperature using an organosol having a volume average particle size of the micrometer or less thus prepared. The grafting efficiency can be improved to produce a toner composition in which dispersibility is maintained for a long time.

A specific method for producing the liquid toner composition according to the present invention will be described through the following examples, and this is compared with a comparative example.

{Example}

Example 1

Preparation of Graft Stabilizers

Old woman 12 (made by Exxon) 2207 g

Trimethylcyclohexyl methacrylate (TCHMA) 849 g

27 g of 2-hydroxyethyl methacrylate (HEMA)

After stirring the material at a speed of 250 rpm under a nitrogen gas atmosphere, the reaction temperature was raised to 70 ° C., and 13 g of V601 (Dimethyl 2,2'-azobis (2-methylpropionate) manufactured by Wakocam, Japan) was previously dissolved in 250 g of old woman 12. The solution was added dropwise using a dropping funnel and reacted for 16 hours.

The reaction mixture was then heated at 90 ° C. at 250 rpm for 1 hour while removing residual V601.

14 g of dibutyltin dilaurate (DBTDL, manufactured by Aldrich Chem Corporation) and 41 g of 3-isoprophenyl dimethylbenzyl isocyanate (TMI, manufactured by Cytec) were added to the reaction mixture. The graft stabilizer was prepared by reacting for 6 hours while stirring at a rate of 250 rpm in a nitrogen gas atmosphere at a temperature of 70 ℃.

The graft stabilizer thus prepared is a copolymer of HEMA comprising a TCHMA and a TMI side chain.

Preparation of Organosol

After raising the reaction temperature to 75 ° C. while stirring 187 g of the graft stabilizer prepared above under a nitrogen gas atmosphere at 250 rpm under a nitrogen gas atmosphere, 374 g of ethyl methacrylate (EMA) 374 g and 18 g of V601 were previously dissolved in 120 g of hapa. Was reacted for 5 hours to prepare an organosol having a volume average particle size of less than micrometers.

The mixture was then cooled to room temperature.

Preparation of Liquid Toner Composition

9.43 g of P.B.15: 4 (product made from Sun Chemical Co., Ltd.)

435.2 g of the prepared organosol (% solid = 13%)

Zirconium HEX-XEM (2.4%) 2.75g

Old woman 12 (made by Exxon) 139.5 g

The material and 1200 g of zirconium beads were placed in an atliter-type milling vessel and milled at 100 ° C. for 3 hours with stirring at a speed of 5000 rpm.

The volume average particle size of the obtained toner thus obtained was about 2.41 mu m.

Example 2

Preparation of Liquid Toner Composition

A liquid toner composition was prepared in the same manner as in Example 1, except that the temperature was 130 ° C. in the milling using the organosol prepared in Example 1.

The volume average particle size of the toner thus obtained was about 3.52 탆.

Comparative example

Preparation of Organosol

Organosol was prepared in the same manner as in Example 1, except that 6 g of V601 was used to prepare an organosol, using the graft stabilizer prepared in Example 1. The volume average particle size of the organosol thus prepared was about 12.5 μm.

The mixture was then cooled to room temperature.

Preparation of Liquid Toner Composition

9.43 g of P.B.15: 4 (product made from Sun Chemical Co., Ltd.)

435.2 g of the prepared organosol (% solid = 13%)

Zirconium HEX-XEM (2.4%) 2.75g

Old woman 12 (made by Exxon) 139.5 g

The material was placed in an attritor-type milling vessel and then 1200 g of zirconium beads were milled at 42 ° C. for 2 hours with stirring at a speed of 5000 rpm to prepare a liquid toner composition.

The volume average particle size of the toner thus obtained was about 3.2 탆.

{Test}

Test method

(1) Determination of Organosol Grafting Efficiency

The grafting efficiency of the graft stabilizer was determined by measuring the% solid of the final organosol prepared in Example 1 and Comparative Example 1 and the% solid of the supernatant after centrifugation.

The grafting efficiency is calculated by centrifuging the organosol% solid two times or more, and then calculating the% solid of the undeposited supernatant RS and the core / shell ratio CS as follows.

(2) dispersion stability

Dispersion stability can be measured by calculating the solidification rate and redispersibility.

After leaving the liquid toner in an oven at 50 ° C. for 6 days, the mass of the measured mass of toner is Y, the weight of the total liquid toner is stirred at X, 600 rpm for 5 minutes, and the weight of the remaining ink mass is Z, and the solidification rate and Redispersion is calculated as follows.

Test results

The test results of Example 1, Example 2 and Comparative Example are shown in Table 1 below.

result Organosol Liquid toner Dispersion Stability of Liquid Toner Volume average particle diameter (㎛) Number average particle diameter (㎛) Grafting Efficiency (%) Volume average particle diameter (㎛) Number average particle diameter (㎛) Solidification rate Redispersion Example 1 0.56 0.29 87.2 2.41 0.67 24% 98.5% Example 2 0.45 0.22 89.2 3.52 0.72 26% 97.8% Comparative example 12.5 7.4 65.1 3.2 1.1 73% 88.0%

As can be seen in Table 1, in the case of the organosol according to Examples 1 and 2, the volume average particle size of the organosol is less than 1㎛, the grafting efficiency is 87% or more, it can be seen that the considerably high.

In addition, the liquid toners according to Examples 1 and 2 have a very small solidification rate and a very high redispersibility of 97% or more as compared with the comparative examples.

Thus, it can be seen that preparing a liquid toner using an organosol having a volume average particle size of less than micrometers preserves the characteristic structure of the core-shell of the organosol, greatly improving the dispersion stability of the liquid toner.

In particular, by milling at a high temperature using an organosol having a volume average particle size of less than micrometers without stripping, it is possible to produce a liquid toner having a desired uniform particle size distribution, thereby eliminating the organosol residual monomer removal process. The organosol process efficiency can be improved and the manufacturing cost can be lowered.

According to the present invention as described above, by producing an organosol having a volume average particle size of less than micrometers and excellent in grafting efficiency, the liquid toner composition is prepared by milling at a high temperature, without impairing the physical properties of the liquid toner itself. There is also an effect that can be produced a liquid toner composition with improved dispersion stability. In addition, the manufacturing method of the liquid toner composition according to the present invention can omit the stripping process, thereby simplifying the process, thereby lowering the manufacturing cost and improving productivity.

Although the above has been illustrated and described with respect to the preferred embodiment of the present invention, the present invention is not limited to the specific preferred embodiment described above, the present invention without departing from the gist of the invention claimed in the claims Various modifications can be made by those skilled in the art, and such changes are within the scope of the claims.

Claims (5)

Preparing a graft stabilizer by mixing and polymerizing a monomer for forming a graft stabilizer and a first polymerization initiator in a first carrier liquid; Preparing a organosol by mixing and polymerizing the prepared graft stabilizer, a thermoplastic (co) polymer core forming monomer, and a second polymerization initiator to a second carrier liquid; And Milling the prepared organosol, colorant, and charge control agent at 90 ° C to 180 ° C in a third carrier liquid to prepare a toner composition. The method of claim 1, In the preparing of the organosol, the content of the second polymerization initiator is in the range of 0.15 to 0.3 parts by weight based on 1 part by weight of the monomer for forming the thermoplastic (co) polymer core. The method of claim 1, The volume average particle size of the prepared organosol is within the range of 0.1 ㎛ to 1.0 ㎛, characterized in that the manufacturing method of the liquid toner composition. delete The method of claim 1, The volume average particle size of the prepared toner particles is in the range of 1 μm to 5 μm.