JP4361466B2 - Yellow toner - Google Patents

Description

  The present invention relates to a yellow toner used for developing a latent image formed in an electrophotographic method, an electrostatic recording method, an electrostatic printing method, and the like, and an image forming method using the yellow toner.

  Conventionally, as a yellow toner for color electrophotography, a toner containing a dichlorobenzidine pigment such as C.I. Pigment Yellow 17 as a colorant has been used. However, since dichlorobenzidine pigments are listed as one of the regulations of Blue Angel, the German Eco Mark, development of yellow toners using colorants that do not have a dichlorobenzidine skeleton is expected. .

  Thus, a toner containing C.I. Pigment Yellow 180 has been reported (see Patent Documents 1 and 2), but the pigment has a great influence on the chargeability, and a sufficient charge amount cannot be obtained. Also, a toner using C.I. Pigment Yellow 180 in combination with a specific charge control agent has been reported (see Patent Document 3).

  Further, there is a growing demand for on-demand printing, and there is a demand for toner that can cope with high image quality and high speed. In particular, from the viewpoint of improving image quality, the conventional contact fixing method using a fixing roll is shifting to a non-contact fixing method using flash fixing or oven fixing.

Therefore, from the viewpoint of improving the fixability and the like in the non-contact fixing method, as a flash fixing toner that is one of the non-contact fixing methods, a toner having a melt viscosity adjusted at the softening point (see Patent Document 4) has been reported. Yes.

JP-A-6-230607 (Claim 1) JP-A-6-266163 (Claim 1) JP-A-8-209017 (Claim 1) JP 58-215660 (Claims 1 and 6)

  SUMMARY OF THE INVENTION An object of the present invention is to provide a yellow toner having a high saturation and a good yellow color, which does not impair the fixing strength even in a non-contact fixing type printing machine, and an image forming method using the yellow toner. There is.

The present invention
[1] A yellow toner containing a binder resin and a colorant, wherein the colorant contains CI pigment yellow 214 and CI pigment yellow 139, and [2] the [1] And an image forming method for fixing an image by a non-contact fixing method.

  The yellow toner of the present invention and the image forming method using the yellow toner have an excellent effect of having a good yellow color with high saturation and not impairing the fixing strength even in a non-contact fixing type printing press. It plays.

  The toner of the present invention contains at least a binder resin and a colorant, and has one feature in that the colorant contains C.I. Pigment Yellow 214 and C.I. Pigment Yellow 139.

  C.I. Pigment Yellow 214 is particularly suitable for an image forming method using a non-contact fixing method because it has excellent heat resistance. In the non-contact fixing method, since heat is indirectly applied to the toner transferred to the printing medium, the toner image is not crushed and high image quality can be provided. However, since it is not a heating method using a hot roll or the like, the thermal conductivity is poor and high heat is required. However, conventional yellow pigments are inferior in heat resistance and cannot maintain a sufficient fixing strength, and color development is also inferior.

  However, the present inventors have found that a combination of C.I. Pigment Yellow 214 and C.I. Pigment Yellow 139 can provide a toner having excellent fixing properties and color developability. Although the details of the reason why the color development is improved by the combined use of CI Pigment Yellow 214 and CI Pigment Yellow 139 are not clear, the dispersion diameter of the colorant may be reduced from a fused photograph of the toner. It has been confirmed that it is presumed that the interaction between the amino group of CI Pigment Yellow 214 and the carbonyl group of CI Pigment Yellow 139 is involved.

  Compounds classified as C.I. Pigment Yellow 214 have the formula (Ia):

It is represented by

  Examples of commercially available C.I. Pigment Yellow 214 include “PV Fast Yellow H9G VP2430” (manufactured by Clariant).

  Compounds classified as C.I. Pigment Yellow 139 have the formula (Ib):

It is represented by

  Examples of commercially available C.I. Pigment Yellow 139 include “Paliotol Yellow D1819” (manufactured by BASF).

  The weight ratio of CI Pigment Yellow 214 to CI Pigment Yellow 139 (CI Pigment Yellow 214 / CI Pigment Yellow 139) is preferably 99/1 to 70/30 from the viewpoint of fixing property and color reproducibility. / 1 to 80/20 is more preferable, and 99/1 to 90/10 is more preferable.

  The total content of CI Pigment Yellow 214 and CI Pigment Yellow 139 is preferably 1 to 15 parts by weight, more preferably 1 to 10 parts by weight, and 1 to 6 parts by weight with respect to 100 parts by weight of the binder resin. Further preferred.

  In the colorant, a colorant other than CI Pigment Yellow 214 and CI Pigment Yellow 139 may be appropriately contained as long as the effects of the present invention are not impaired, but CI Pigment Yellow 214 in the colorant may be contained. And CI Pigment Yellow 139 is preferably 80% by weight or more, and more preferably 90% by weight or more.

  Examples of the binder resin in the present invention include known resins used for toners, such as polyester, styrene-acrylic resin, epoxy resin, polycarbonate, polyurethane, and the like. Among them, polyester and styrene-acrylic copolymer are used. Preferably, polyester is more preferable from the viewpoints of colorant dispersibility, fixability, and durability. The content of the polyester is preferably 50% by weight or more, more preferably 80% by weight or more, and further preferably 100% by weight in the binder resin.

  As a raw material monomer for polyester, a known divalent or higher valent alcohol component and a known carboxylic acid component such as a divalent or higher carboxylic acid, carboxylic acid anhydride, or carboxylic acid ester are used.

  As the alcohol component, the formula (II):

(Wherein R ¹ is an alkylene group having 2 or 3 carbon atoms, x and y are positive numbers, and the sum of x and y is 1 to 16, preferably 1.5 to 5.0) It is preferably contained.

  Compounds represented by formula (II) include polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) Examples include bisphenol A alkylene (2 to 3 carbon) oxide (average added mole number 1 to 16) adducts such as propane. Other alcohol components include ethylene glycol, propylene glycol, glycerin, pentaerythritol, trimethyloglycol propane, hydrogenated bisphenol A, sorbitol, or their alkylene (2 to 4 carbon atoms) oxide (average added mole number 1 -16) Additives etc. are mentioned, and it is preferable to contain one or more of these.

  The content of the compound represented by the formula (II) is preferably 5 mol% or more, more preferably 50 mol% or more, further preferably 80 mol% or more, and particularly preferably 100 mol% in the alcohol component.

  As the carboxylic acid component, dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, fumaric acid and maleic acid, alkyl groups having 1 to 20 carbon atoms such as dodecenyl succinic acid and octyl succinic acid, or those having 2 to 20 carbon atoms. Examples thereof include succinic acid, trimellitic acid, pyromellitic acid substituted with an alkenyl group, anhydrides of these acids, and alkyl (1 to 3 carbon atoms) esters of these acids, which contain one or more of these. Those are preferred.

  Further, the alcohol component and the carboxylic acid component may appropriately contain a monovalent alcohol or a monovalent carboxylic acid compound from the viewpoint of adjusting the molecular weight.

  The polyester can be produced, for example, by subjecting an alcohol component and a carboxylic acid component to condensation polymerization at a temperature of 180 to 250 ° C. in an inert gas atmosphere, if necessary, using an esterification catalyst.

  It is preferable that the softening point of the polyester is 95 to 160 ° C., the glass transition point is 50 to 75 ° C., the acid value is 1 to 40 mgKOH / g, and the hydroxyl value is 3 to 60 mgKOH / g.

  Further, the toner of the present invention includes a charge control agent, a release agent, a fluidity improver, a conductivity modifier, an extender, a reinforcing filler such as a fibrous substance, an antioxidant, an anti-aging agent, and an improved cleaning property. An additive such as an agent may be appropriately contained.

  A known charge control agent can be used as the charge control agent. For example, chromium / azo complex dyes; iron azo complex dyes; cobalt / azo complex dyes; metal compounds of salicylic acid or derivatives thereof; chromium / zinc / aluminum / boron complexes or salt compounds of naphtholic acid or derivatives thereof; benzylic acids or derivatives thereof Chromium / zinc / aluminum / boron complexes or salt compounds; surfactants such as long chain alkyl / carboxylates, long chain alkyl / sulfonates, nigrosine dyes and derivatives thereof, triphenylmethane derivatives, quaternary ammonium salts And derivatives of quaternary phosphonium salts, quaternary biridinium salts, guanidine salts, amidine salts, and the like.

  Among the charge control agents, since the toner of the present invention is a yellow toner, a white charge control agent is preferable. From the viewpoint of the hue and chargeability of the charge control agent, the formula (III):

Wherein R ² , R ³ and R ⁴ are each independently a hydrogen atom, a linear or branched alkyl group or alkenyl group having 1 to 10 carbon atoms, M is zinc, zirconium, chromium, aluminum, Copper, nickel or cobalt, m is an integer of 2 or more, and n is an integer of 1 or more)
A metal compound of a salicylic acid derivative represented by The metal compound of the salicylic acid derivative may be either a metal salt or a metal complex, or may be a single compound or two or more compounds may be used in combination.

In the formula (III), R ³ is preferably a hydrogen atom, and R ² and R ⁴ are preferably a branched alkyl group, more preferably a tert-butyl group.

  As M, zinc and chromium are preferable because of their high electronegativity and good charging effect.

As a commercially available product suitably used in the present invention, wherein R ³ is a hydrogen atom and R ² and R ⁴ are tert-butyl groups, “Bontron E-84” (M: zinc, manufactured by Orient Chemical Industries, Ltd.) "TN-105" (M: Zirconium, manufactured by Hodogaya Chemical Co., Ltd.), "Bontron E-81" (M: Chrome, manufactured by Orient Chemical Industry Co., Ltd.), "Bontron E-88" (M: Aluminum, manufactured by Orient Chemical Co., Ltd.) and the like.

  The content of the charge control agent is preferably 0.1 to 10 parts by weight and more preferably 0.1 to 5 parts by weight with respect to 100 parts by weight of the binder resin. In particular, from the viewpoint of charge amount and stability, the weight ratio (charge control agent / yellow pigment) of the charge control agent and the yellow pigment (CI pigment yellow 214 and CI pigment yellow 139) is 99/1 to 30/70. Is preferable, and 99/1 to 50/50 is more preferable.

  As the release agent, low molecular weight polypropylene, low molecular weight polyethylene, low molecular weight polypropylene polyethylene copolymer, aliphatic hydrocarbon waxes such as microcrystalline wax, paraffin wax, and Fischer-Tropsch wax and their oxides, carnauba wax, Examples include ester waxes such as montan wax, sasol wax and their deoxidized wax, fatty acid amides, fatty acids, higher alcohols, fatty acid metal salts and the like. The content of the release agent is preferably 0.1 to 20 parts by weight and more preferably 1 to 10 parts by weight with respect to 100 parts by weight of the binder resin.

  Among these, paraffin wax is preferable from the viewpoint of fixability. The paraffin wax that is preferably used in the present invention is a wax that is solid at room temperature and separated and purified from vacuum distilled distillate.

  Commercially available paraffin wax products include “HNP-9” (manufactured by Nippon Seiwa Co., Ltd., melting point: 79 ° C.), “HNP-5” (manufactured by Nippon Seiwa Co., Ltd., melting point: 66 ° C.), “HNP-10” ( Nippon Seiwa Co., Ltd., melting point: 82 ° C.), “SP-3040” (Nippon Seiwa Co., Ltd., melting point: 65 ° C.) and the like.

  The content of the paraffin wax is preferably 0.5 to 6 parts by weight and more preferably 1.5 to 3 parts by weight with respect to 100 parts by weight of the binder resin.

The toner of the present invention may be any toner such as pulverized toner, polymerized toner, and capsule toner. For example, as a general method for producing a pulverized toner, a binder resin, a colorant, and an additive such as a charge control agent are uniformly mixed with a mixer such as a Henschel mixer or a ball mill, and then a sealed kneader or a single screw. Or the method of melt-kneading with a biaxial extruder etc., cooling, grind | pulverizing, and classifying is mentioned. The toner of the present invention preferably has a volume-median particle size (D ₅₀ ) of 3 to 10 μm. In the present invention, the volume-median particle size (D ₅₀ ) means a particle size at which the cumulative volume frequency calculated by the volume fraction is 50% when calculated from the smaller particle size.

  Further, the toner and the external additive are stirred and mixed with a high-speed stirrer such as a super mixer or a Henschel mixer, and the external additive is added to the toner surface of the present invention by a method such as attaching the external additive to the toner surface. It may be added.

  Examples of the external additive in the present invention include inorganic fine particles such as silicon dioxide (silica), titanium dioxide, aluminum oxide, zinc oxide, magnesium oxide, cerium oxide, iron oxide, copper oxide, and tin oxide. From the viewpoint of imparting chargeability, silica and titanium dioxide are preferable, and silica is more preferable. The inorganic fine particles can be used alone or in combination of two or more. In the present invention, at least one of the inorganic fine particles used as an external additive is an organic silicon having an organic group such as a trimethyl group. What was hydrophobized with the compound is preferable.

  The average particle diameter of the inorganic fine particles is preferably 1 to 200 nm, more preferably 5 to 100 nm, and further preferably 5 to 80 nm from the viewpoints of chargeability and fluidity. In the present invention, the particle size of the inorganic fine particles is determined using a scanning electron microscope or a transmission electron microscope. Examples of such commercially available inorganic fine particles include “AEROSIL R972” (Nippon Aerosil, hydrophobic silica, average particle size: 16 nm), “AEROSIL R974” (Nippon Aerosil, hydrophobic silica, average particle size: 12 nm), “H2000 / 4” (manufactured by Hoechst, hydrophobic silica, average particle size: 16 nm), and the like.

  The yellow toner of the present invention has a particularly excellent effect on the fixing strength. Therefore, the present invention further provides an image forming method for fixing an image by a non-contact fixing method using the yellow toner of the present invention. The non-contact fixing method is a fixing method in which a heat source is heated without directly contacting the toner, and heat energy is transmitted by radiation or convection, and there are flash fixing by an infrared lamp and oven fixing by a surface heater. From the viewpoint of high image quality, the oven fixing method is preferable.

  In the contact fixing method using the fixing roll, when the toner is crushed due to the pressure of the fixing roll, the image quality is deteriorated. Further, since the toner and the fixing roll are in contact with each other, offset is likely to occur. On the other hand, in the non-contact fixing method, the transferred toner is fixed without applying external force from a fixing roll or the like, so that it is easy to improve the image quality, while heat is transferred to the toner through a medium such as a fixing roll. Since the toner is not transmitted, the toner is likely to be insufficiently melted, and has the disadvantage that it is inferior in color development particularly required for the color toner. However, since the toner of the present invention contains CI Pigment Yellow 214 and CI Pigment Yellow 139, which are excellent in heat resistance, as colorants, it can be suitably used in a non-contact fixing system at higher temperatures. Excellent fixability and color development.

The image forming method of the present invention preferably includes at least the following steps. Note that the image forming method of the present invention can be used in combination with other toners such as magenta toner, cyan toner, black toner, etc. An image may be formed.
(Step 1) Step of forming a latent image on the latent image carrier (Step 2) Step of forming a toner image on the latent image carrier (Step 3) Step of transferring the toner image onto the transfer member (Step) 4) The process of fixing the transferred image by a non-contact fixing method.

  The yellow toner of the present invention is a two-component developer as a developer alone when containing a magnetic fine powder, or as a non-magnetic one-component developer when not containing a magnetic fine powder, or mixed with a carrier. In the present invention, it is preferably used as a two-component developer from the viewpoint of excellent durability.

  As the carrier used when the yellow toner of the present invention is used as a two-component developer, a carrier having a low saturation magnetization that makes the magnetic brush weak is preferable from the viewpoint of image characteristics.

In the present invention, from the viewpoint of image characteristics, it is preferable to use a carrier with low saturation magnetization that weakens the area around the magnetic brush. Saturation magnetization of the carrier is preferably ^{40~100Am 2 / kg, 50~90Am 2 /} kg is more preferable. The saturation magnetization is preferably 100 Am ² / kg or less from the viewpoint of adjusting the hardness of the magnetic brush and maintaining gradation reproducibility, and preferably 40 Am ² / kg or more from the viewpoint of preventing carrier adhesion and toner scattering.

  As the core material of the carrier, those made of known materials can be used without particular limitation, for example, ferromagnetic metals such as iron, cobalt, nickel, magnetite, hematite, ferrite, copper-zinc-magnesium ferrite, Examples include alloys and compounds such as manganese ferrite and magnesium ferrite, and glass beads. Among these, iron powder, magnetite, ferrite, copper-zinc-magnesium ferrite, manganese ferrite, and magnesium ferrite are preferable from the viewpoint of chargeability. From the viewpoint of image quality, ferrite, copper-zinc-magnesium ferrite, manganese ferrite and magnesium ferrite are more preferable.

  The surface of the carrier is preferably coated with a resin from the viewpoint of reducing carrier contamination. The resin that coats the carrier surface varies depending on the toner material. For example, fluororesin such as polytetrafluoroethylene, monochlorotrifluoroethylene polymer, polyvinylidene fluoride, silicone resin such as polydimethylsiloxane, polyester, styrenic resin, Acrylic resins, polyamides, polyvinyl butyral, amino acrylate resins, and the like can be used, and these can be used alone or in combination of two or more. However, when the toner is negatively charged, the chargeability and surface From the viewpoint of energy, a silicone resin is preferable. The method for coating the core material with the resin is not particularly limited, for example, a method in which a coating material such as a resin is dissolved or suspended in a solvent and applied to the core material, or a method of simply mixing with a powder.

  In the two-component developer of the present invention obtained by mixing the toner and the carrier, the toner to carrier weight ratio (toner / carrier) is preferably 1/99 to 10/90, and 2/98 to 8/92. More preferred.

  The yellow toner of the present invention and the two-component developer containing the yellow toner are effective in scattering toner even in a high-speed developing device having a linear speed of preferably 200 mm / sec or more, more preferably 200 mm / sec or more. Therefore, it can be suitably used. The linear speed of the developing device referred to in the present invention refers to the peripheral speed of the magnet roller.

[Softening point of resin]
Using a Koka type flow tester (CFT-500D, manufactured by Shimadzu Corporation), a 1 g sample was heated at a heating rate of 6 ° C / min. A nozzle with a thickness of 1 mm is pushed out, thereby drawing a plunger tester drop amount (flow value) -temperature curve of the flow tester, and when the height of the S-shaped curve is h, the temperature corresponding to h / 2 (resin The temperature at which half flows out) is taken as the softening point.

[Glass transition point of resin]
Using a differential scanning calorimeter (Seiko Denshi Kogyo Co., Ltd., DSC210) to raise the temperature to 200 ° C, and when the sample was cooled from that temperature to a temperature drop rate of 10 ° C / min. The temperature at the intersection of the extension of the baseline below the maximum peak temperature of the heat of fusion and the tangent showing the maximum slope from the peak rising portion to the peak apex is defined as the glass transition point of the resin.

[Resin acid value]
Measured by the method of JIS K0070.

[Carrier saturation magnetization]
(1) Fill a plastic case with a lid with an outer diameter of 7 mm (inner diameter of 6 mm) and a height of 5 mm while tapping the carrier, and calculate the mass of the carrier from the difference between the weight of the plastic case and the weight of the plastic case filled with the carrier. .
(2) Set the plastic case filled with the carrier in the sample holder of the magnetic property measurement device “BHV-50H” (VSMAGNETOMETER) of RIKEN ELECTRONICS CO., LTD., While vibrating the plastic case using the vibration function, Saturation magnetization is measured by applying a magnetic field of 79.6 kA / m. The obtained value is converted into saturation magnetization per unit mass in consideration of the mass of the filled carrier.

Resin production example 1
Polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane 1705g, terephthalic acid 328g, fumaric acid 1050g and dibutyltin oxide 2.5g equipped with nitrogen introduction tube, dehydration tube, stirrer and thermocouple The mixture was placed in a 5-liter four-necked flask, reacted at 230 ° C. for 8 hours, and further reacted at 8.3 kPa until a predetermined softening point was reached. The obtained resin had an acid value of 19 mgKOH / g, a hydroxyl value of 23 mgKOH / g, a softening point of 108 ° C., and a glass transition point of 60 ° C. The obtained resin is designated as polyester A.

Examples 1 and 2 and Comparative Examples 1 to 3
100 parts by weight of polyester A, colorant and charge control agent “Bontron E-81” (manufactured by Orient Chemical Co., Ltd.) and paraffin wax “HNP-9” (manufactured by Nippon Seiwa Co., Ltd., melting point: 79 ° C.) 2 parts by weight are mixed with a Henschel mixer, melt-kneaded with a twin screw extruder, cooled, and then crushed and classified using a collision plate type pulverizer “Dispersion Separator” (manufactured by Nippon Pneumatic Industry Co., Ltd.). The toner having the volume-median particle size (D ₅₀ ) shown in Table 1 was obtained.

  To 100 parts by weight of the obtained toner, 0.6 parts by weight of hydrophobic silica “H2000 / 4” (manufactured by Hoechst, average particle size: 16 nm) was added, and the mixture was stirred for 3 seconds at 3200 r / min with a 10 liter Henschel mixer for 180 seconds. The yellow toner was obtained by sieving with a mesh of 100 μm mesh.

Test Example 1 [Hue]
Toner 48g coated ferrite carrier (average particle size: 65 .mu.m, saturation magnetization: 68Am ² / kg) 56g were placed in cylindrical polybottle of 1L volume, to secure the container in a tumbler shaker mixer, the speed of 90r / min And rotated for 10 minutes to obtain a two-component developer.

The obtained two-component developer was mounted on a commercially available electrophotographic recording apparatus, and an unfixed image having a toner adhesion amount of 0.6 mg / cm ² was obtained. The obtained unfixed image was held in an oven set at 150 ° C. for 15 seconds and fixed by a non-contact fixing method. Using a color meter “SPM50” (manufactured by Gretag), L ^* value, a ^* value, b ^* value, saturation (C ^* value), hue under measurement conditions where the measurement light is D ₅₀ and the viewing angle is 2 ° The hab was measured. The results are shown in Table 1.

Test Example 2 [Fixability]
In the same manner as in Test Example 1, an unfixed image having a toner adhesion amount of 0.6 mg / cm ² was obtained and heat-fixed in an oven at 150 ° C. for 15 seconds. The image was rubbed 3 times on the image with a white paper with a load of 1 kg applied to an area of 1.5 cm × 1 cm. The image density before and after rubbing was measured using a color meter “SPM50” (manufactured by Gretag), and the fixing ratio was calculated from (image density after rubbing) / (image density before rubbing) × 100. The results are shown in Table 1.

  From the above results, the toners of Examples 1 and 2 have a hue angle close to an ideal yellow color, a high saturation value, and a high fixing rate. On the other hand, the toner of Comparative Example 1 using only C.I. Pigment Yellow 214 has a large hue angle (green as a hue), is not an ideal yellow color, and has low saturation. The toner of Comparative Example 2 using only C.I. Pigment Yellow 139 has high saturation, but has a small hue angle (red hue) and is not an ideal yellow color. The toner of Comparative Example 3 using C.I. Pigment Yellow 180 has a large hue angle, is not an ideal yellow color, and has low saturation. Further, it can be seen that the toners of Comparative Examples 1 to 3 are inferior to the toners of Examples 1 and 2 and are difficult to use in the non-contact fixing method.

  The yellow toner of the present invention is suitably used for developing a latent image formed in electrophotography, electrostatic recording method, electrostatic printing method and the like.

Claims (6)

  A yellow toner comprising a binder resin and a colorant, wherein the colorant comprises C.I. Pigment Yellow 214 and C.I. Pigment Yellow 139.   The yellow toner according to claim 1, wherein the weight ratio of C.I. Pigment Yellow 214 to C.I. Pigment Yellow 139 (C.I. Pigment Yellow 214 / C.I. Pigment Yellow 139) is 99/1 to 70/30.   The yellow toner according to claim 1 or 2, wherein the total content of C.I. Pigment Yellow 214 and C.I. Pigment Yellow 139 is 1 to 15 parts by weight with respect to 100 parts by weight of the binder resin.   The yellow toner according to claim 1, wherein the binder resin contains polyester.   The yellow toner according to claim 1, comprising paraffin wax as a release agent.   An image forming method for fixing an image by a non-contact fixing method using the yellow toner according to claim 1.