KR20060083718A - Preparation of the liquid 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 into a third carrier liquid to prepare a toner composition, wherein the second polymerization initiator is involved in the polymerization reaction in the second carrier liquid. It contains a polymerization initiator whose half life is 10 hours or more at high temperature more than degreeC. According to the present invention, an organosol is prepared at a high temperature of 80 ° C. or higher to prepare a liquid toner composition in which residual monomers are significantly lowered, thereby providing an effect of improving mass productivity of the liquid toner composition.

Organosol, toner

Description

Process for preparing liquid toner composition {Preparation of the liquid toner composition}

The present invention relates to a method for producing a liquid toner composition. More specifically, the present invention relates to a method for producing a liquid toner composition, which can reduce manufacturing costs by preparing an organosol using a polymerization initiator having a high reaction temperature region to prepare a liquid toner composition.

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 used by electric force to form and print a desired image on the recording medium.

The electrophotographic image forming apparatus can be roughly classified into a dry electrophotographic image forming apparatus using a dry toner and a liquid electrophotographic image forming apparatus using a liquid toner, that is, a liquid toner, according to the type of toner used. have.

Liquid toner has advantages of relatively high resolution, faster printing speed, and use of a smaller amount of toner, because the toner particles are dispersed and used on a liquid carrier as compared to dry toner. .

Liquid toners are often composed of toner particles composed of a colorant that realizes color and a polymer resin as a binder, a charge control agent that controls the amount of charge charged on the toner particles, and a carrier liquid in which they are dispersed. In addition, additives may be further included to improve the functionality of the toner.

The liquid toner used in the wet electrophotographic image forming apparatus may be classified into a liquid toner using a common commercial resin and an organosol liquid toner using an organosol, depending on the binder resin used.

Organosol liquid toner has a merit that high-resolution images can be realized because the toner particles have a diameter of several micrometers and are charged stably.

Conventional methods for preparing organosol liquid toner include a graft stabilizer including a grafting functional group, a core monomer and a polymerization initiator, together with a carrier liquid, stir at room temperature, raise the polymerization temperature, and polymerize by a free radical reaction for a predetermined time. The reaction was allowed to occur. Next, a core-shell structured organosol was finally prepared through a stripping process for removing residual monomer. This organosol was then dispersed with a colorant and a charge control agent to prepare a liquid toner composition having a volume average particle size of finally less than 5 micrometers.

When the residual monomer is present in the preparation of the organosol, the concentration affects the charge characteristics of the prepared liquid toner. Thus, when the organosol is prepared by a polymerization reaction in a dispersed phase, the residual monomer is less than or equal to a certain concentration. In order to ensure this, the stripping process must be carried out.

Stripping is a process of removing residual monomers by reducing the pressure at a high temperature above the polymerization temperature, so it must be carried out at a high vacuum temperature of 100 ° C. or higher and 10 torr or less, so that expensive equipment must be installed and the process is complicated.

In addition, the organosol particles are agglomerated during the stripping process to increase the particle size. In order to adjust the final liquid toner particle size to the required size, it is necessary to manufacture the liquid toner by changing the milling conditions or the milling time. It is also difficult to secure reproducibility of organosol.

The present invention has been made to solve the above problems, and an object of the present invention is to simplify the organosol manufacturing process of the organosol toner and reduce the process cost during mass production without impairing the physical properties of the toner itself. It is to provide a method of preparing the composition.

According to an aspect of the present invention, there is provided a method of preparing a liquid toner composition, comprising: 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, the thermoplastic (co) polymer core forming monomer, and the second polymerization initiator in a second carrier liquid; And

Milling the prepared organosol, colorant and charge control agent into a third carrier liquid to prepare a toner composition;

The second polymerization initiator includes a polymerization initiator having a half-life of 10 hours or more at a high temperature of 80 ° C. or higher when involved in the polymerization reaction in the second carrier liquid.

The second polymerization initiator is 1,1'-azobis (cyclohexane-1-carbonitrile) (1,1'-azobis (cyclohexane-1-carbonitrile)) or 2,2'-azobis (N-butyl- 2-methylpropionamide) (2,2'-azobis (N-butyl-2-methylpropionamide)).

It is preferred that the second carrier liquid is an aliphatic hydrocarbon or an aromatic hydrocarbon.

The second polymerization initiator may further include the same kind as the first polymerization initiator.

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

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 of these monomers can be selected and mixed. However, the monomer which can be used is not limited to this.

The first and second carrier liquids that can be used in the preparation of graft stabilizers and in the preparation of organosols are aliphatic hydrocarbon solvents, cyclic hydrocarbon solvents, aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, silicone oils and waxes, polyethylene waxes, stearates, respectively. Acid amides or mixtures thereof, but the carrier liquids that can be used are not limited thereto.

In particular, the second carrier liquid that can be used for the preparation of the organosol is selected from aliphatic hydrocarbons such as n-pentane, hexane and heptane, cyclohydrocarbons such as cyclopentane and cyclohexane, and aromatic hydrocarbons such as benzene, toluene and xylene. It is desirable to. Commercially available examples include Isopar G, Isopar H, Isopar K, Isopar L, Isopar M, Isopar V, and Nopa 12 from Exxon Corporation. ), And the old woman 15.

The first and second polymerization initiators which can be used for the preparation of the graft stabilizer and the organosol include water-soluble or fat-soluble persulfates, peroxides and azobis compounds, respectively, It can mix and use species.

In particular, it is preferable that the half life of the 2nd polymerization initiator which can be used for manufacture of an organosol is a high temperature area | region. Since the reaction temperature range becomes high temperature, the polymerization initiator whose half life is high temperature can accelerate the speed | rate of the polymerization reaction of a monomer, and improve the efficiency of a polymerization reaction so that a monomer may not exist in an unreacted state after completion | finish of reaction.

Since the temperature range of the half-life of the polymerization initiator depends on the degree of dissolution in the solvent of the polymerization initiator to be used and the type of monomer to be involved in the reaction, the selection of the polymerization initiator may vary depending on the type of monomer and the carrier liquid used.

In the method for producing a liquid toner composition according to the present invention, it is preferable that the carrier liquid used in the preparation of the organosol is a hydrocarbon, and therefore, the second polymerization initiator is preferably an azobis compound. In particular, the second polymerization initiator is 1,1'-azobis (cyclohexane-1-carbonitrile) (1,1'-azobis (cyclohexane-1-carbonitrile)) or 2,2'-azobis (N-butyl -2-methylpropionamide) (2,2'-azobis (N-butyl-2-methylpropionamide)).

In addition, the 2nd polymerization initiator used at the time of manufacture of an organosol can be used together with the thing other than the polymerization initiator mentioned above, In particular, the thing of the same kind as a 1st polymerization initiator can be used together. The use together here does not mean using "simultaneously" but rather means that they can be used together for the polymerization reaction for the preparation of the organosol.

Therefore, an organosol can be manufactured by carrying out a 1st polymerization reaction as a polymerization initiator whose half life is not high temperature area | region, and then raising reaction temperature and performing a secondary polymerization reaction as a polymerization initiator whose half life is high temperature region.

The content of the polymerization initiator used in the preparation of the organosol is within 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 volume average particle size of the prepared organosol is less than a few micrometers, and unreacted monomers remaining in the carrier liquid are significantly suppressed so that no stripping process is required.

Preparation of the final toner composition is made by milling the organosol, colorant and charge control agent in a third carrier liquid.

Examples of the material that can be used as the third carrier liquid include 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, Halogenated hydrocarbon solvents such as fluorinated 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. Commercially available examples include Isopar G, Isopar H, Isopar K, Isopar L, Isopar M, Isopar V, and Nopa 12 from Exxon Corporation. ), And the old woman 15.

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 high, so that the viscosity of the liquid toner is high, which makes it difficult to control the liquid toner, resulting in a problem of printing an image even in the non-image area. This is because the larger the content of the colorant is, the lower the concentration of the colorant is, the lower the OD of the image area of the printed image, the liquid toner is easily consumed, and frequent replacement is inevitable.

The coloring agent of a toner composition can use either a dye type coloring agent or a pigment type coloring agent. However, it is preferable to use the pigment type coloring agent which shows the superiority 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. , Sulfates, silicates, carbonates, phosphates, metal powders, carbon black, and the like, and the pigments described above can be used alone or in combination of two or more thereof. However, the pigment which can be used is not limited to this.

When the pigment-based colorant that can be used in the present invention is classified by color, there are the following.

Blue and / or green pigments include copper phthalocyanine, Pigment Blue (PB) 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 16, and metal-free 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, 155, 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 the pigments that can be used are not limited thereto.

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, lecithin, polyvinylpyrrolidone, basic barium petronates and calcium Petronates and the like. However, the charge control agent which can be used is not limited to this. An example of a commercially available charge control agent is Zirconium HEX-CEM from Patterned Chemical, Inc. of Cleveland, Ohio.

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 functions as a binder and a dispersant in the liquid toner. When the content is less than 10 parts by weight, it is difficult to expect the function as a dispersant. When the content of the organosol is more than 50 parts by weight, the content of the colorant is relatively high. There is a problem that it becomes smaller and the sharpness of the printed image is lowered.

In the preparation of the liquid toner composition according to the present invention, the content of the charge control agent 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 is difficult to control the amount of charge charged to the toner particles, and thus, it is difficult to obtain a clear image because the OD (Optical Density) of the image area is not obtained and the image density is lowered. to be.

The liquid toner composition is prepared by putting a polymerization initiator in a state in which a colorant and a charge control agent are dispersed in an organosol, and milling together with beads in a milling vessel. Milling equipment that can be used for milling is a ball mill, Dino mill, EIGER MILL 250, or Dispermat. Preferably, milling is carried out at a speed of 1000 to 10000 rpm with zirconium beads in an atliter dispermet.

The volume average particle size of the toner particles of the toner composition thus prepared is within the range of 0.1 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 particles are too fine, problems may occur in the transfer or fixing step in the environment where the toner composition is used. It is desirable to be in range.

The method of manufacturing the liquid toner composition as described above has the advantage of simplifying the process and reducing the cost since the complicated and difficult stripping process can be omitted in the preparation of the organosol.

A specific method for preparing the liquid toner composition according to the present invention will be described through the following examples and compared with the 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 rate 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 added to 250 g of old woman 12. The dissolved 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.

To the reaction mixture was added 14 g of dibutyltin dilaurate (DBTDL, manufactured by Aldrich Chem Corporation) and 41 g of 3-isopropenyl dimethylbenzyl isocyanate (Cytec), which were then heated under a nitrogen gas atmosphere at a temperature of 70 ° C. A graft stabilizer was prepared by reacting for 6 hours while stirring at 250 rpm.

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

Preparation of Organosol

The reaction temperature was raised to 75 ° C. while stirring 187 g of the graft stabilizer prepared above in a nitrogen gas atmosphere at 250 rpm in a nitrogen gas atmosphere, and then 374 g of ethyl methacrylate (EMA) 374 g and 12.6 g of V601 were previously added to 120 g of hapa 12. The dissolved solution was added dropwise using a dropping funnel and reacted for 2 hours.

Then, the reaction temperature was raised to 95 ° C., and a solution of 6 g of V40 (1,1′-azobis (cyclohexane-1-carbonitrile) manufactured by Wakochem Co., Ltd.) was added dropwise to 20 g of old woman 12 using a dropping funnel. Reaction was carried out for 3 hours to prepare an organosol.

The resulting mixture was then cooled to room temperature.

Preparation of Liquid Toner Composition

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

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

Zirconium HEX-CEM (2.4%) 2.75g

Old woman 12 (made by Exxon) 139.5 g

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

In this way, a liquid toner composition was finally prepared.

Example 2

Preparation of Organosol

The reaction temperature was raised to 95 ° C. while stirring 187 g of the graft stabilizer prepared in Example 1 together with 2814 g of NOPA 12 at a rate of 250 rpm in a nitrogen gas atmosphere, and 374 g of ethyl methacrylate (EMA) was added to 120 g of NOPA 12 in advance. Organosol was prepared by dropping a solution of 12.6 g of V40 using a dropping funnel and reacting for 5 hours.

The mixture was then cooled to room temperature.

Preparation of Liquid Toner Composition

A liquid toner composition was prepared in the same manner as in Example 1 except for using the prepared organosol.

Comparative example

Preparation of Organosol

The reaction temperature was raised to 75 ° C. while stirring 187 g of the graft stabilizer prepared in Example 1 at 250 rpm under a nitrogen gas atmosphere together with 2814 g of hapa 12, and then 374 g of ethyl methacrylate and 12.6 g of V601 in 120 g of hapa 12 in advance. The dissolved solution was reacted for 5 hours to prepare an organosol.

The organosol prepared above was then cooled to room temperature. The final organosol was removed by adding 350 g of n-heptane to the cooled organosol and removing the residual monomers using a rotary evaporator equipped with a dry ice / acetone condenser and operated at 97 ° C. and 15 mmHg vacuum. Prepared.

Preparation of Liquid Toner Composition

A liquid toner composition was prepared in the same manner as in Example 1 except for using the prepared organosol.

{Test}

Immediately after the preparation of the organosol prepared in Examples 1, 2 and Comparative Examples, the supernatant was taken through centrifugation, and the residual monomer was measured by measuring the concentration of ethyl methacrylate by GC-MSD. Measured.

In the organosol suitable for the preparation of the liquid toner composition, the residual monomer tolerance of ethyl methacrylate is 100 ppm or less.

The test results are shown in Table 1 below.

result Organosol Liquid toner composition Volume average particle diameter (㎛) Remaining monomers Volume average particle diameter (µm) / Number average particle diameter (µm) Charge amount Q / M of liquid toner Before stripping After stripping Example 1 0.75 ± 0.08 78 ± 8 - 0.76 / 0.38 102 ± 10 Example 2 0.82 ± 0.06 82 ± 10 - 0.78 / 0.42 105 ± 7 Comparative example 0.45 ± 0.25 2600 ± 152 68 ± 20 0.59 / 0.30 113 ± 10

As can be seen from Table 1, the organosol prepared according to Example 1 and Example 2, the remaining monomer is within the allowable value without performing the stripping process, while in the comparative example the remaining monomer is within the allowable value after performing the stripping process Became.

Therefore, when the liquid toner was prepared using the organosol prepared according to the present invention, the characteristics of the liquid toner similar to those obtained through the conventional stripping process could be obtained. It is possible to prepare the organosol by using an initiator having a high half-life alone or in combination with an initiator whose half-life is not high, thereby eliminating the stripping process for removing residual monomers, and accelerating the polymerization reaction, thereby efficiently preparing liquid toner. That means you can.

According to the present invention as described above, by preparing the organosol using a polymerization initiator having a half-life in a high temperature region, it is possible to simplify the manufacturing process of the liquid toner by eliminating the stripping process for the removal of the residual monomer, and also the polymerization reaction There is an effect that can be accelerated to provide a method for producing a liquid toner having improved efficiency.

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 into a third carrier liquid to prepare a toner composition; And the second polymerization initiator comprises a polymerization initiator having a half-life of 10 hours or more at a high temperature of 80 ° C or higher when engaging in a polymerization reaction in the second carrier liquid. The method of claim 1, The second polymerization initiator is 1,1'-azobis (cyclohexane-1-carbonitrile) (1,1'-azobis (cyclohexane-1-carbonitrile)) or 2,2'-azobis (N-butyl- 2-methylpropionamide) (2,2'-azobis (N-butyl-2-methylpropionamide)). The method of claim 1, And said second carrier liquid is a hydrocarbon selected from the group consisting of aliphatic hydrocarbons, cyclic hydrocarbons and aromatic hydrocarbons. The method of claim 2, And the second polymerization initiator further comprises the same kind as the first polymerization initiator. The method of claim 1, The volume average particle size of the prepared toner particles is in the range of 0.1 μm to 5 μm.