Toner and Two-Component Developer Containing the Same

Abstract

To provide a toner capable of obtaining both low-temperature fixability and heat-resistant storage stability, and a two-component developer containing the same.SOLUTION: A toner contains at least a binder resin and a release agent. The binder resin contains a side chain type liquid crystalline polyester resin having a liquid crystalline site in a side chain.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a toner capable of achieving both low-temperature fixability and heat-resistant storage stability, and a two-component developer containing the same.

Background Art

[0002] In recent years, with the remarkable development of OA equipment, image forming apparatuses such as copiers, printers, and facsimile machines using the electrophotographic method have been widely spread, and various image forming methods have been proposed and put into practical use. For example, in a heat fixing method in which toner is heated and melted to fix a toner image on a recording paper, in order to achieve energy saving, it is necessary to fix the toner image at as low a temperature as possible, and a toner with good low-temperature fixability is required. In order to improve the low-temperature fixability of toner, for example, a technique of adding a trace amount of crystalline polyester to amorphous polyester as a binder resin has been proposed. By adding crystalline polyester, the viscosity of the toner can be sharply reduced, and the melting temperature can be reduced. However, as the addition amount of crystalline polyester increases, the crystallinity in the toner increases, and the domain diameter of the sharp melt of crystalline polyester increases, thereby deteriorating the heat-resistant storage stability and the fixing characteristics on the high-temperature side of the toner. Therefore, there is a limit to the addition amount of crystalline polyester, and it has been difficult to expand the low-temperature fixing region.

[0003] Various techniques have been proposed to improve the problems of the toner as described above. For example, Japanese Patent Publication No. 6-56503 (Patent Document 1) proposes a toner composition comprising resin particles selected from the group consisting of thermotropic liquid crystalline polycarbonate, copolycarbonate, polyurethane, polyester, and copolyester, and a pigment resin.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0005] The toner resin composition described in Patent Document 1 contains a thermotropic liquid crystal polymer having a liquid crystal expressing site arranged in the main chain as a main component, has a high softening point, and is difficult to use as a binder resin for toner.

[0006] Therefore, an object of the present invention is to provide a toner capable of achieving both low-temperature fixability and heat-resistant storage stability, and a two-component developer containing the same.

MEANS FOR SOLVING THE PROBLEMS

[0007] As a result of intensive studies to solve the above problems, the present inventor has found that by using a liquid crystalline polyester having a liquid crystal expressing site in the side chain as a binder resin, an increase in the sharp melt domain diameter of the toner can be suppressed, heat-resistant storage stability can be maintained, and due to a sharp decrease in viscosity around the phase transition temperature, the low-temperature side of the fixable region can be expanded. It has been found that the softening point can be controlled by the number of liquid crystal expressing sites on the side chain side, that is, the resin can be easily made to have a low melting point, and the resin design for low-temperature fixing is easy, and the present invention has been completed.

[0008] Thus, according to the present invention, there is provided a toner containing at least a binder resin and a release agent, wherein the binder resin contains a side-chain type liquid crystalline polyester resin having a liquid crystal expressing site in the side chain.

[0009] Further, according to the present invention, there is provided a two-component developer containing the above toner and a carrier.

EFFECTS OF THE INVENTION

[0010] According to the present invention, it is possible to provide a toner capable of achieving both low-temperature fixability and heat-resistant storage stability, and a two-component developer containing the same.

MODE FOR CARRYING OUT THE INVENTION

[0011] (1) Toner The toner of the present invention at least contains a binder resin and a release agent, and is characterized in that the binder resin contains a side-chain type liquid crystalline polyester resin having a liquid crystalline expressing site in the side chain. The side-chain type liquid crystalline polyester resin changes its crystallinity due to temperature changes. At low temperatures, the liquid crystalline expressing sites are oriented, showing properties similar to those of a crystalline polyester resin. When the temperature exceeds the threshold temperature, i.e., the liquid crystal isotropic phase transition temperature Tni, the orientation of the molecules collapses, the viscosity sharply decreases, and the same effects as those of a crystalline polyester resin can be obtained. On the other hand, since the crystalline domains of the side-chain type liquid crystalline polyester resin are dispersed at the molecular level, an increase in the domain diameter does not occur with an increase in the addition amount, and the heat-resistant storage property and the fixing property on the high-temperature side do not deteriorate. Therefore, it is possible to replace all of the binder resin with a liquid crystalline polyester resin without using a combination of high-molecular-weight and low-molecular-weight polyester resins as in the prior art. Hereinafter, the binder resin, which is a characteristic part of the toner of the present invention, will be described, and the toner (also referred to as "toner mother particles"), which is the basis of the toner, the manufacturing method of the toner, and the two-component developer containing the toner will be described.

[0012] (1-1) Binder resin In the toner of the present invention, the side-chain liquid crystalline polyester resin contained as a binder resin, unlike ordinary polyester resins, assumes a glass state, a liquid crystal phase state, and an isotropic phase state as the temperature rises. Below the glass transition temperature Tg, it becomes a glass state and does not show fluidity, similar to ordinary polyester resins. On the other hand, when the temperature exceeds the glass transition temperature Tg, it undergoes a phase transition from the glass state to the liquid crystal phase state, and the flexible parts of the liquid crystalline polyester resin start molecular motion and show slight fluidity, but the molecules are oriented like those of a crystalline polyester resin, having blocking resistance and offset resistance. Further, when the temperature exceeds the liquid crystal isotropic phase transition temperature Tni, it undergoes a phase transition to the isotropic phase state, becomes a molten state like ordinary polyester resins, and fixing becomes possible. In the present invention, by using such a liquid crystalline polyester in a specific temperature range, low-temperature fixing can be realized while maintaining sufficient thermal properties.

[0013] (Glass transition temperature Tg) According to an embodiment of the present invention, the side-chain liquid crystalline polyester resin preferably has a glass transition temperature Tg of 50°C or higher and 70°C or lower. If the glass transition temperature Tg is less than 50°C, the heat storage stability and the high-temperature region side of fixing may deteriorate. On the other hand, if the glass transition temperature Tg exceeds 70°C, the low-temperature fixability may deteriorate. A more preferable glass transition temperature Tg is 60°C or higher and 70°C or lower. The method for measuring the glass transition temperature Tg will be described in the examples.

[0014] (Liquid crystal isotropic phase transition temperature Tni) According to an embodiment of the present invention, the side-chain liquid crystalline polyester resin preferably has a liquid crystal isotropic phase transition temperature Tni of 100°C or higher and 140°C or lower. The liquid crystal isotropic phase transition temperature Tni means the temperature at which the phase transition occurs from the liquid crystal phase in which the molecules are oriented to the isotropic phase in which the molecules are not oriented. If the liquid crystal isotropic phase transition temperature Tni is less than 100°C, the heat storage stability and the high-temperature region side of fixing may deteriorate. On the other hand, if the liquid crystal isotropic phase transition temperature Tni exceeds 140°C, the low-temperature fixability may deteriorate. A more preferable liquid crystal isotropic phase transition temperature Tni is 120°C or higher and 130°C or lower. The method for measuring the liquid crystal isotropic phase transition temperature Tni will be described in the examples.

[0015] (Peak top molecular weight Mp) According to an embodiment of the present invention, the side-chain liquid crystalline polyester resin preferably has a peak top molecular weight Mp of 4,000 or more and 15,000 or less in GPC measurement. When the peak top molecular weight Mp is less than 4,000, the heat-resistant storage property and the high-temperature region side of fixing may deteriorate. On the other hand, when the peak top molecular weight Mp exceeds 15,000, the low-temperature fixing property may deteriorate. A more preferable peak top molecular weight Mp is 8,000 or more and 15,000 or less. The method for measuring the peak top molecular weight Mp will be described in the examples.

[0016] (Resin structure) The side-chain liquid crystalline polyester resin is a side-chain liquid crystalline polymer and has a polymer backbone in the main chain and a liquid crystal-forming site in the side chain. Compared with the main-chain liquid crystalline polyester resin, the side-chain liquid crystalline polyester resin shows a lower glass transition temperature Tg and liquid crystal isotropic phase transition temperature Tni, and the thermal properties can be controlled by the type and introduction rate of the main-chain backbone and the side chain to be introduced, which is preferable.

[0017] According to an embodiment of the present invention, the side-chain liquid crystalline polyester resin preferably has any one selected from siloxane, acrylic, and methacrylic in the main-chain backbone. These main-chain backbones are generally used in liquid crystalline polyesters. In addition to the ease of introducing side chains, the glass transition temperature Tg can be adjusted by selecting the main-chain backbone, which is preferable.

[0018] Also, according to an embodiment of the present invention, the side-chain liquid crystalline polyester resin has the following structural formula as a liquid crystal-forming site: [Chemistry] It preferably has a side chain having as a basic skeleton any one selected from p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, and biphenyl represented by . In addition to being commonly used, these skeletal structures exhibit a low melting point, low viscosity in a high-temperature state, and are suitable for low-temperature fixing.

[0019] (Liquid crystal phase) The liquid crystal phase has different names depending on the order of the oriented molecular orientation, and there are a nematic phase, a smectic phase, a cholesteric phase, etc. In the toner of the present invention, any phase form may be used. Among these phase forms, the nematic phase has the lowest order, the collapse and formation of the molecular orientation are carried out rapidly, and the viscosity decrease accompanying the temperature rise is sharper than that of other phases. Therefore, an effect equivalent to that of a crystalline polyester resin can be obtained. Also, regarding the viscosity, the nematic phase has a lower viscosity than other phases. From these facts, by using a liquid crystalline polyester resin that forms a nematic phase, the low-temperature fixability of the toner can be improved. Therefore, according to an embodiment of the present invention, the side-chain liquid crystalline polyester resin preferably has a nematic phase as the liquid crystal phase.

[0020] (Content) According to an embodiment of the present invention, the side-chain liquid crystalline polyester resin is preferably contained in the toner at a ratio of 50% by mass or more and 85% by mass or less. If the content of the side-chain liquid crystalline polyester resin in the toner is less than 50% by mass, the liquid crystallinity of the side-chain liquid crystalline polyester resin in the toner may not be exhibited. On the other hand, if the content in the toner exceeds 85% by mass, the resin ratio in the toner increases and the ratio of the additive decreases, so the properties of the toner may deteriorate significantly. A more preferable content of the side-chain liquid crystalline polyester resin in the toner is 70% by mass or more and 85% by mass or less.

[0021] (Other binder resins) The toner of the present invention may contain, as a binder resin, crystalline and amorphous polyester resins commonly used in the art, in addition to the above side-chain type liquid crystalline polyester resin, as long as the effects of the present invention are not inhibited. In the case of combined use with a side-chain type liquid crystalline polyester resin, an amorphous polyester resin is preferred. The content of the preferred amorphous polyester resin in the toner is 0% by mass or more and 30% by mass or less, more preferably 0% by mass or more and 15% by mass or less.

[0022] (1-2) Release agent The release agent contained in the toner of the present invention has a function of imparting releasability to the toner when the toner is fixed to a recording medium, and release agents commonly used in the art can be used. Examples of the release agent include petroleum waxes such as paraffin wax and microcrystalline wax and their derivatives; hydrocarbon synthetic waxes such as Fischer-Tropsch wax, polyolefin waxes (such as polyethylene wax and polypropylene wax), low molecular weight polypropylene wax, and polyolefin polymer waxes (such as low molecular weight polyethylene wax) and their derivatives; plant waxes such as carnauba wax, rice wax, and candelilla wax and their derivatives, and wood wax; animal waxes such as beeswax and whale wax; oil and fat synthetic waxes such as fatty acid amide and phenol fatty acid ester; long-chain carboxylic acids and their derivatives; long-chain alcohols and their derivatives; silicone polymers; higher fatty acids, etc. Among these, hydrocarbon waxes are preferred. The above derivatives include oxides, block copolymers of vinyl monomers and waxes, graft-modified products of vinyl monomers and waxes, etc. In the present invention, one of the above release agents can be used alone or in combination of two or more.

[0023] The content of the release agent in the toner of the present invention is not particularly limited, but is preferably 0.5 to 5% by mass, more preferably 2 to 4% by mass. If the content of the release agent is within the above range, a toner capable of achieving both low-temperature fixability and heat-resistant storage stability can be obtained without impairing various physical properties of the toner. Also, in order to improve the dispersibility of the release agent in the toner, a release agent dispersant such as a styrene-acrylic copolymer resin may be used in combination.

[0024] (1-3) Colorant The toner of the present invention may contain a colorant as necessary, within a range that does not inhibit the effects of the present invention, and various types and colors of pigments and dyes, organic and inorganic, commonly used in the art can be used. Examples include colorants such as black, white, yellow, orange, red, purple, blue, and green.

[0025] Examples of black colorants include carbon black, copper oxide, manganese dioxide, aniline black, activated carbon, non-magnetic ferrite, magnetic ferrite, and magnetite. Examples of white colorants include zinc white, titanium oxide, antimony white, and zinc sulfide.

[0026] Examples of yellow colorants include lead yellow, zinc yellow, cadmium yellow, yellow iron oxide, mineral fast yellow, nickel titanium yellow, naphthol yellow S, hansa yellow G, hansa yellow 10G, benzidine yellow G, benzidine yellow GR, quinoline yellow lake, permanent yellow NCG, tartrazine lake, C.I. Pigment Yellow 12, C.I. Pigment Yellow 13, C.I. Pigment Yellow 14, C.I. Pigment Yellow 15, C.I. Pigment Yellow 17, C.I. Pigment Yellow 93, C.I. Pigment Yellow 94, C.I. Pigment Yellow 138, etc.

[0027] Examples of orange colorants include red lead, molybdenum orange, permanent orange GTR, pyrazolone orange, vulcan orange, indanthrene brilliant orange RK, benzidine orange G, indanthrene brilliant orange GK, C.I. Pigment Orange 31, C.I. Pigment Orange 43, etc.

[0028] Examples of red colorants include red iron oxide, cadmium red, red lead, mercury sulfide, cadmium, permanent red 4R, rhodamine red, pyrazolone red, watching red, calcium salt, lake red C, lake red D, brilliant carmine 6B, eosin lake, rhodamine lake B, alizarin lake, brilliant carmine 3B, C.I. Pigment Red 2, C.I. Pigment Red 3, C.I. Pigment Red 5, C.I. Pigment Red 6, C.I. Pigment Red 7, C.I. Pigment Red 15, C.I. Pigment Red 16, C.I. Pigment Red 48:1, C.I. Pigment Red 53:1, C.I. Pigment Red 57:1, C.I. Pigment Red 122, C.I. Pigment Red 123, C.I. Pigment Red 139, C.I. Pigment Red 144, C.I. Pigment Red 149, C.I. Pigment Red 166, C.I. Pigment Red 177, C.I. Pigment Red 178, C.I. Pigment Red 222, etc.

[0029] Examples of purple colorants include manganese violet, fast violet B, methyl violet lake, etc. Examples of blue colorants include ultramarine, cobalt blue, alkali blue lake, victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, phthalocyanine blue partial chloride, first sky blue, indanthrene blue BC, C.I. Pigment Blue 15, C.I. Pigment Blue 15:2, C.I. Pigment Blue 15:3, C.I. Pigment Blue 16, C.I. Pigment Blue 60, etc. Examples of the green colorant include chrome green, chromium oxide, pigment green B, mica green lake, final yellow green G, C.I. pigment green 7, and the like.

[0030] In the toner of the present invention, one of the above colorants can be used alone or in combination of two, and the combination may be of different colors or the same color. Alternatively, two or more colorants may be used after being made into composite particles. The composite particles can be produced, for example, by adding an appropriate amount of water, lower alcohol, etc. to two or more colorants, granulating with a general granulator such as a high-speed mill, and drying. Further, in order to uniformly disperse the colorant in the binder resin, it may be used in the form of a masterbatch. The composite particles and the masterbatch are mixed into the toner composition during dry mixing.

[0031] The content of the colorant in the toner of the present invention is not particularly limited, but is preferably 2 to 10% by mass, more preferably 3 to 10% by mass. If the content of the colorant is within the above range, a toner capable of achieving both low-temperature fixability and heat-resistant storage stability can be obtained without impairing various physical properties of the toner.

[0032] (1-4) Charge control agent (charge control agent) The toner of the present invention may contain a charge control agent as necessary within a range that does not inhibit the effects of the present invention, and charge control agents for positive charge control and negative charge control commonly used in the art can be used. Examples of the charge control agent for positive charge control include nigrosine dyes, basic dyes, quaternary ammonium salts, quaternary phosphonium salts, aminopyrine, pyrimidine compounds, polynuclear polyamino compounds, aminosilanes, nigrosine dyes and their derivatives, triphenylmethane derivatives, guanidine salts, amidine salts, and the like. Examples of the charge control agent for negative charge control include oil-soluble dyes such as oil black and spiron black, metal-containing azo compounds, azo complex dyes, metal salts of naphthenic acid, metal complexes and metal salts of salicylic acid and its derivatives (the metal is chromium, zinc, zirconium, etc.), boron compounds, fatty acid soaps, long-chain alkyl carboxylates, resin soaps, and the like. In the toner of the present invention, one of the above charge control agents can be used alone or in combination of two or more. In the toner of the present invention, one of the above charge control agents can be used alone or in combination of two or more.

[0033] The content of the charge control agent in the toner of the present invention is not particularly limited, but is preferably 0.5 to 5% by mass, more preferably 1 to 4% by mass. If the content of the charge control agent is within the above range, a toner can be obtained that can achieve both low-temperature fixability and heat-resistant storage stability without impairing various physical properties of the toner.

[0034] (1-5) Externally added agent The toner may contain an externally added agent in order to improve its transportability, chargeability, and agitation property with the carrier in the two-component developer. As the externally added agent, externally added agents commonly used in the art can be used. Examples include inorganic fine particles such as silica and titanium oxide. Those surface-treated (hydrophobicized) with silicone resin, silane coupling agent, etc. are preferred. In terms of imparting chargeability to the toner, silica particles are particularly preferred. Also, the externally added agent is preferably inorganic fine particles having an average primary particle diameter of 6 to 200 nm. The addition amount of the externally added agent is not particularly limited, but is preferably 0.2 to 5.0 parts by mass, more preferably 0.5 to 2.5 parts by mass, based on 100 parts by mass of the toner.

[0035] (1-6) Method for producing toner The toner used in the present invention can be manufactured by known methods using known apparatuses commonly used in the art, for example, a mixing and kneading step of mixing and kneading a material containing at least a binder resin and a release agent, a coarse pulverization step of coarsely pulverizing the obtained melt-kneaded product to obtain a coarsely pulverized product, a fine pulverization step of finely pulverizing the obtained coarsely pulverized product to obtain a finely pulverized product, a classification step of classifying the obtained finely pulverized product to obtain toner mother particles, and an external addition step of adding an external additive to the toner mother particles and mixing them to obtain an externally added toner. The dry method is preferred in that it has fewer process steps and does not require high equipment costs compared to the wet method. Among them, the pulverization method is particularly preferred. The conditions in each of the following steps may be appropriately set according to the target material and desired physical properties.

[0036] (2) Two-component developer The two-component developer of the present invention is characterized by containing the toner of the present invention and a carrier. (Carrier) The toner of the present invention can be used in either the form of a one-component developer or a two-component developer. When used as a two-component developer, it further contains a carrier in addition to the external additive. As the carrier, carriers commonly used in the art can be used, for example, single or composite ferrites composed of iron, copper, zinc, nickel, cobalt, manganese, chromium, etc., and those in which the surface of carrier core particles is coated with a known coating material. The average particle size of the carrier is preferably 10 to 100 μm, more preferably 20 to 50 μm. The content of the carrier is not particularly limited, but is preferably 85 to 97% by mass, more preferably 90 to 95% by mass, based on the total amount of the developer.

Examples

[0037] Hereinafter, the present invention will be specifically described by synthesis examples, examples and comparative examples. However, the present invention is not limited to the following examples as long as the gist thereof is not exceeded. In the examples and comparative examples, each physical property value was measured by the methods shown below.

[0038] [Measurement of Tg and Tni of Liquid Crystal Polyester] Using a differential scanning calorimeter (manufactured by Seiko Instruments Inc. (currently Hitachi High-Tech Science Corporation), model: DSC220), 1 g of the toner sample was heated to 200°C at a heating rate of 10°C / min, then held at 200°C for 2 minutes, and cooled to 30°C at a cooling rate of 10°C / min to measure the DSC curve. The endothermic peak temperature (glass transition temperature) Tg (°C) on the low-temperature side and the endothermic peak temperature (liquid crystal isotropic phase transition temperature) Tni (°C) on the high-temperature side of the obtained DSC curve were determined.

[0039] [Measurement of Tg and Tm of Amorphous Polyester] In the same manner as the above DSC measurement, the DSC curve of the amorphous polyester was measured. The endothermic peak temperature (glass transition temperature) Tg (°C) on the low-temperature side and the endothermic peak temperature (melting temperature) Tm (°C) on the high-temperature side of the obtained DSC curve were determined.

[0040] [Measurement of Outflow Start Temperature and Softening Temperature of Toner] Using a flow property evaluation apparatus (manufactured by Shimadzu Corporation, Flow Tester, model number: CFT-100C), while heating 1 g of the sample from an initial temperature of 40°C at a heating rate of 6°C / min, a load of 20 kgf / cm 2 (9.8×105 Pa) was applied, and the sample was made to flow out from a die (nozzle diameter 1 mm, length 1 mm). The temperature at which the sample began to flow out was defined as the outflow start temperature "Ti", and the temperature at which half of the sample had flowed out was defined as the softening temperature "Tm".

[0041] [GPC Measurement (Peak Top Molecular Weight: Mp)] The peak top molecular weight (Mp) of the binder resin and the toner was measured under the following conditions using gel permeation chromatography (GPC). The peak top molecular weight refers to the molecular weight indicating the maximum peak height in the chromatogram obtained by GPC measurement. In the measurement of molecular weight, a polyester resin is dissolved in tetrahydrofuran (THF), and the undissolved portion is filtered off with a glass filter and used as a sample solution. (Apparatus and Conditions) Apparatus: Manufactured by Tosoh Corporation, Model: HLC-8120 Column: Two TSK GEL GMH6 columns manufactured by Tosoh Corporation Measurement temperature: 40 °C Sample solution: 0.25 mass% THF solution Solution injection volume: 100 μl Detector: Refractive index detector Reference substance: Twelve standard polystyrenes (TSKstandard POLYSTYRENE) manufactured by Tosoh Corporation (molecular weights 500, 1050, 2800, 5970, 9100, 18100, 37900, 96400, 190000, 355000, 1090000, and 2890000)

[0042] (Synthesis Example 1: Synthesis of Liquid Crystal Polyester A) 90 mL of methanol was added to a 300 mL glass flask equipped with a stirrer, a reflux condenser, and a dropping funnel, and 27.7 g of p-hydroxybenzoic acid was dissolved therein. 34.2 g of potassium hydroxide was dissolved in 220 mL of methanol, and this was added dropwise to the p-hydroxybenzoic acid solution, followed by stirring at room temperature (25 °C) for 2 hours. 26 mL of allyl chloride was added to the resulting solution, and the mixture was stirred at 70 °C for 6 hours. Thereafter, the solvent was distilled off under reduced pressure, and the resulting reaction product was washed with 160 mL of water and 160 mL of diethyl ether. Thereafter, hydrochloric acid was added to the resulting aqueous solution for neutralization, and the precipitated precipitate was recrystallized with isopropanol to obtain Compound A.

[0043] 4.93 g of Compound A and 70 mL of thionyl chloride were added to a 300 mL glass flask equipped with a stirrer, and the mixture was stirred for 2 hours. Thereafter, the solvent was distilled off under reduced pressure, and 30 mL of dichloromethane was added to prepare a Compound A solution. To 17 mL of dichloromethane, 5.21 g of p-methoxyphenol and 8.66 mL of triethylamine were added. After dropping them into the solution of Compound A under an ice bath, the mixture was stirred for 6 hours. Then, the solvent was distilled off under reduced pressure, and the obtained reaction product was washed with ethyl acetate and an aqueous sodium hydroxide solution, and recrystallized from ethanol to obtain a mesogen which is a liquid crystal exhibiting site.

[0044] To a 50 mL glass flask equipped with a stirring device and a reflux condenser, 0.501 g of mesogen, 0.139 g of polymethylsiloxane and 5 mL of toluene were added, and the inside of the flask was made into a nitrogen atmosphere. Then, a catalytic amount of hexachloroplatinic(IV) acid hexahydrate was added, and the reaction was carried out at a temperature of 110 °C for 24 hours. The solvent was distilled off under reduced pressure, and the obtained reaction product was purified by a reprecipitation method using methanol as a poor solvent and toluene as a good solvent to obtain 0.309 g of liquid crystalline polyester A (Resin A) as a side-chain liquid crystalline polyester resin. By NMR analysis, it was confirmed that the obtained resin is Resin A having siloxane in the main chain skeleton and p-hydroxybenzoic acid in the side chain skeleton, and by polarized light microscope observation, the obtained resin is in a liquid crystal state having a nematic phase as a liquid crystal phase. Also, by the above measurement method, the glass transition temperature Tg, the liquid crystal isotropic phase transition temperature Tni and the peak top molecular weight Mp of Resin A were measured.

[0045] (Synthesis Examples 2 to 10: Synthesis of Liquid Crystalline Polyesters B to J) Instead of the siloxane in the main chain skeleton and p-hydroxybenzoic acid in the side chain skeleton, acrylic or methacrylic shown in Table 1 and 6-hydroxy-2-naphthoic acid or biphenyl were used respectively, and in the same manner as in Synthesis Example 1, liquid crystalline polyesters B to J (Resins B to J) were obtained as side-chain liquid crystalline polyester resins.

[0046] (Synthesis Example 11: Synthesis of Amorphous Polyester K) In a reaction vessel with a capacity of 5 L, 440 g (2.7 mol) of terephthalic acid, 235 g (1.4 mol) of isophthalic acid, 7 g (0.05 mol) of adipic acid, 554 g (8.9 mol) of ethylene glycol, and 0.5 g of tetrabutoxytitanate as a polymerization catalyst were added, and the reaction was carried out for 5 hours while distilling off the water and ethylene glycol generated at 210°C under a nitrogen stream. Then, the reaction was carried out for 1 hour under a reduced pressure of 5 to 20 mmHg. Next, 103 g (0.54 mol) of trimellitic anhydride was added, and after reacting for 1 hour under normal pressure, the reaction was carried out under a reduced pressure of 20 to 40 mmHg, and the resin was taken out at a predetermined softening point. The recovered ethylene glycol was 219 g (3.5 mol). After cooling the obtained resin to room temperature, it was granulated by grinding and used as amorphous polyester resin K. The amorphous polyester resin K had a Tm of 145°C and a peak top molecular weight Mp of 12,000.

[0047] (Synthesis Example 12: Synthesis of Amorphous Polyester L) An amorphous polyester L having a predetermined softening point was obtained in the same manner as in Synthesis Example 11.

[0048] (Example 1) <Material Mixing, Kneading, Grinding, and Classification Process> Binder Resin: 84% by mass of Resin A (glass transition temperature Tg 50°C, liquid crystal isotropic phase transition temperature Tni 140°C, peak top molecular weight Mp 15,000, see Synthesis Example 1) Colorant: Carbon Black (manufactured by Cabot Corporation, product name: Regal1330) 6% by mass Release Agent: 3% by mass of an ester wax (manufactured by NOF Corporation, product name: WEP8) Release Agent Dispersant: 5% by weight of a styrene-acrylic copolymer resin (manufactured by Mitsui Chemicals, Inc., product name: SA800) Charge Control Agent: 2% by mass of a salicylic acid-based compound (Orient Chemical Industries Co., Ltd., product name: Bontron E-84)

[0049] Using an airflow mixer (Henschel mixer, manufactured by Mitsui Mining Co., Ltd. (currently Nippon Coke & Engineering Co., Ltd.), model: FM20C), the above materials were premixed for 5 minutes. Then, using a twin-screw extruder (manufactured by Ikegai Corporation, model: PCM30), melt-kneading was carried out under the conditions of a cylinder set temperature of 110 °C, a barrel rotation speed of 300 rpm, and a raw material supply rate of 20 kg / hour to obtain a melt-kneaded product [Mixing and kneading process]. After cooling the obtained melt-kneaded product with a cooling belt, it was roughly pulverized using a cutting mill (manufactured by Orient Corporation, model: VM-16) to obtain a roughly pulverized product [Rough pulverization process]. Next, the obtained roughly pulverized product was finely pulverized using a jet mill (manufactured by Nippon Pneumatic Mfg. Co., Ltd., model: IDS-2) to obtain a finely pulverized product [Fine pulverization process]. The obtained finely pulverized product was classified using an air classifier (manufactured by Nippon Steel Mining Co., Ltd., model: EJ-LABO) to obtain toner mother particles with an average primary particle diameter of 6.5 μm [Classification process].

[0050] <External addition process> To 100 parts by mass of the obtained toner mother particles, 1.0 part by mass of commercially available silica fine particles (average primary particle diameter 7 nm, manufactured by Aerosil Co., Ltd., product name: R976S) was added, and the obtained mixture was mixed for 2 minutes using an airflow mixer (Henschel mixer, manufactured by Mitsui Mining Co., Ltd. (currently Nippon Coke & Engineering Co., Ltd.), model: FM20C) under the set condition of a tip speed of the stirring blade of 40 m / s to obtain an externally added toner [External addition process].

[0051] <Manufacturing process of resin-coated carrier> 0.375 parts by weight of coating resin (1) (silicone-based, trade name: KR240, manufactured by Shin-Etsu Chemical Co., Ltd.) and 0.375 parts by weight of coating resin (2) (trade name: KR251, manufactured by Shin-Etsu Chemical Co., Ltd.) were dissolved in 12 parts by weight of toluene. To this solution, 0.0375 parts by weight of conductive particles (trade name: VULCAN XC-72, manufactured by Cabot Corporation) and 0.0225 parts by weight of a coupling agent (trade name: AY43-059, manufactured by Toray Dow Corning Co., Ltd.) were added and dispersed to prepare a coating resin solution. By the dipping method, 12.8 parts by weight of the coating resin solution was used to coat the surface of 100 parts by weight of a ferrite carrier core material having a volume average diameter of 40 μm. Thereafter, through a curing process at a curing temperature of 200 °C and a curing time of 1 hour, the carrier was produced by sieving through a sieve with an opening of 150 μm.

[0052] <Manufacturing process of developer> The obtained externally added toner and the resin-coated carrier were put into a V-type mixer (manufactured by Tokuju Kousakusho Co., Ltd., trade name: V-5) so that the externally added toner concentration with respect to the total amount of the two-component developer was 7% by mass, and mixed for 30 minutes to obtain a two-component developer with a toner concentration of 7%.

[0053] (Examples 2 to 12) Except for using the binder resin shown in Table 1, externally added toner and developer were obtained in the same manner as in Example 1. For the binder resin of Example 5, 50% by mass of resin B of the liquid crystalline polyester resin and 34% by mass of resin K of the amorphous polyester resin were used. For resin K, an amorphous polyester resin synthesized using PO-BPA (propoxylated bisphenol A) and EO-BPA (ethoxylated bisphenol A) as aromatic alcohol components and fumaric acid and maleic anhydride as acid components, having an outflow start temperature Ti of 105 °C, a melting temperature Tm of 145 °C, and a peak top molecular weight Mp of 12,000 in the flow tester measurement, was used.

[0054] Also, for the binder resin of Example 6, 45% by mass of resin B of the liquid crystalline polyester resin and 39% by mass of resin L of the amorphous polyester resin were used. For the resin L, PO-BPA and EO-BP were used as aromatic alcohol components A and an amorphous polyester resin synthesized using fumaric acid and maleic anhydride as acid components, having an outflow start temperature Ti of 104 °C, a melting temperature Tm of 112 °C, and a peak top molecular weight Mp of 5,500 in the flow tester measurement was used.

[0055] (Comparative Examples 1 - 2) External additive toners and developers were obtained in the same manner as in Example 1, except that the binder resins shown in Table 1 were used. For the binder resin of Comparative Example 1, 84% by mass of the resin L of the amorphous polyester resin was used instead of the liquid crystalline polyester resin.

[0056] For the binder resin of Comparative Example 2, 84% by mass of the resin M of the main-chain liquid crystalline polyester resin was used instead of the liquid crystalline polyester resin. For the resin M, a commercially available main-chain liquid crystalline polyester resin having a main chain with p-hydroxybenzoic acid as a basic skeleton, a glass transition temperature Tg of 45 °C, a liquid crystal isotropic phase transition temperature Tni of 210 °C, and a peak top molecular weight Mp of 10,000 was used.

[0057] [Evaluation] The toners and two-component developers prepared in Examples 1 - 12 and Comparative Examples 1 - 2 were evaluated for the following items, and a comprehensive evaluation was performed based on the results. The obtained results are shown in Table 2.

[0058] [Evaluation 1: Fixing property (low-temperature fixing property and high-temperature fixing property)] Using a commercially available copying machine (manufactured by Sharp Corporation, model: MX-M5100FN) modified for evaluation, the fixing property of the two-component developer was evaluated. First, a sample image including a solid image (a rectangle 20 mm long and 50 mm wide) was formed as an unfixed image on recording paper (manufactured by Sharp Corporation, PPC paper, model: SF-4AM3). At this time, the amount of toner adhered to the recording paper in the solid image was adjusted to be 0.5 mg / cm 2 to be. Next, a fixed image was produced using a hard roller fixing device. The fixing process speed was set at 120 mm / second, and the temperature of the fixing roller was increased in 5°C increments from 110°C to determine the minimum and maximum temperatures at which low-temperature offset and high-temperature offset did not occur, respectively. "Low-temperature offset" and "high-temperature offset" are defined as the toner not being fixed to the recording paper during fixing, but instead adhering to the recording paper after the fixing belt has made one full rotation while remaining attached to the fixing belt.

[0059] From the results obtained, the "low-temperature fixability" was determined according to the following criteria. A: The minimum temperature is less than 110°C B: The minimum temperature is 110°C or higher and less than 120°C C: The minimum temperature is 120°C or higher and less than 125°C D: The minimum temperature is 125°C or higher and less than 130°C E: The minimum temperature is 130°C or higher Also, from the results obtained, the "high-temperature fixability" was determined according to the following criteria. A: The maximum temperature is 195°C or higher B: The maximum temperature is 185°C or higher and less than 195°C C: The maximum temperature is 180°C or higher and less than 185°C D: The maximum temperature is 175°C or higher and less than 180°C E: The maximum temperature is less than 175°C

[0060] [Evaluation 2: Heat-resistant storage stability] The heat-resistant storage stability was evaluated based on the presence or absence of aggregates after high-temperature storage. 5 g of the prepared externally added toner was weighed (total toner weight: g), placed in a 50 mL plastic container, sealed, and left at a temperature of 50°C for 48 hours. After that, the toner was taken out, classified using a 200-mesh sieve, and the toner remaining on the sieve was weighed (toner weight on the sieve: g). The ratio of the toner weight on the sieve to the total toner weight, which was weighed in advance, was determined as the remaining amount (%) and the heat-resistant storage stability was evaluated according to the following evaluation criteria. A: The remaining amount is less than 0.5% B: The remaining amount is 0.5% or higher and less than 7% C: The remaining amount is 7% or higher and less than 10% D: The remaining amount is 10% or more and less than 12% E: The remaining amount is 12% or more) The lower the numerical value of the remaining amount, the less likely the toner is to cause blocking, which means that the toner mother particles are sufficiently coated with the coating layer.

[0061] [Comprehensive Judgment] Based on the above evaluation results, a comprehensive judgment was made according to the following criteria. A: All evaluation items are A (usable) B: There is a B in even one evaluation item (usable) C: There is a C in even one evaluation item (usable) D: There is a D in even one evaluation item (usable) E: There is an E in even one evaluation item (unusable)

[0062]

Table 1

[0063]

Table 2

[0064] It can be seen from Tables 1 and 2 as follows. (1) The two-component developer (Examples 1 to 12) containing the toner having the requirements of the present invention can achieve both low-temperature fixability and heat-resistant storage stability (2) On the other hand, the two-component developer (Comparative Examples 1 and 2) containing the toner not having the requirements of the present invention cannot achieve both low-temperature fixability and heat-resistant storage stability (3) The two-component developer (Example 9) containing a toner using a resin with a low glass transition temperature Tg is excellent in low-temperature fixing property but inferior in high-temperature fixing property. The two-component developer (Example 10) containing a toner using a resin with a high glass transition temperature Tg is excellent in high-temperature fixing property but inferior in low-temperature fixing property. From this, within the suitable range of the glass transition temperature Tg, the high-temperature and low-temperature fixing properties can be maintained at a certain level or higher. However, by adjusting the glass transition temperature Tg to a more optimal range, the high-temperature and low-temperature fixing properties can be brought to a level that is more than sufficient (4) The two-component developers (Examples 5 and 6) containing a toner obtained by mixing a side-chain liquid crystalline polyester and an amorphous polyester are both inferior in high-temperature and low-temperature fixing properties. From this, it is preferable to use the side-chain liquid crystalline polyester alone, and adding an amorphous polyester may inhibit the expression of the properties of the side-chain liquid crystalline polyester

Claims

1. Comprising at least a binder resin and a release agent, wherein the binder resin contains a side-chain type liquid crystalline polyester resin having a liquid crystalline moiety in the side chain, The side-chain type liquid crystalline polyester resin has a peak top molecular weight Mp of 8,000 or more and 15,000 or less in GPC measurement, The side-chain type liquid crystalline polyester resin has, as a liquid crystalline moiety, the following structural formula: 【Chemical 1】 It has a side chain having as a basic skeleton any one selected from 6-hydroxy-2-naphthoic acid and biphenyl represented by A toner characterized by the above.

2. The toner according to claim 1, wherein the side-chain type liquid crystalline polyester resin has a glass transition temperature Tg of 50°C or more and 70°C or less.

3. The toner according to claim 1 or 2, wherein the side-chain type liquid crystalline polyester resin has any one selected from siloxane, acrylic, and methacrylic in the main chain skeleton.

4. The toner according to any one of claims 1 to 3, wherein the side-chain type liquid crystalline polyester resin has a nematic phase as a liquid crystal phase.

5. The toner according to any one of claims 1 to 4, wherein the side-chain type liquid crystalline polyester resin is contained in the toner in a proportion of 50% by mass or more and 85% by mass or less.

6. A two-component developer comprising the toner according to any one of claims 1 to 5 and a carrier.

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