JP2007316164A - Method for producing toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To produce a toner in which the amount of the bleed out of waxes is remarkably reduced, which has offset resistance, a wide non-offset region and an excellent fixability to a recording medium, whose flocculation upon preservation is hard to occur, and which can form a high resolution image with a high image density. <P>SOLUTION: In a melt emulsification process where a molten kneaded matter of a toner raw material and an aqueous medium comprising a dispersant are mixed under heating, so as to produce toner particles, two or more kinds of waxes each having a melting point of 60 to 100°C are incorporated into the toner raw material, thus the dispersibility of the waxes in the obtained toner particles is improved, so as to prevent the bleed out of the waxes to the toner particle surfaces. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a toner manufacturing method.

  An electrophotographic image forming apparatus includes a photosensitive member, a charging unit that charges the surface of the photosensitive member, and an exposure that irradiates signal light onto the charged photosensitive member surface to form an electrostatic latent image corresponding to image information. Means, a developing means for supplying a toner in the developer to the electrostatic latent image on the surface of the photosensitive member to form a toner image, a transfer means comprising a transfer roller for transferring the toner image on the photosensitive member surface to a recording medium, A one-component developer or toner that includes an image forming process such as a fixing unit that includes a fixing roller that fixes a toner image on a recording medium and a cleaning unit that cleans the surface of the photoconductor after the toner image is transferred. The electrostatic latent image is developed using a two-component developer containing particles and a carrier to form an image. General toner particles are resin particles in which a colorant, a wax as a release agent, and the like are dispersed in a binder resin. The toner particles are melted by heating in a fixing unit and exhibit pressure. By being received, the image is formed by fixing on the surface of the recording medium. Wax as a release agent has an effect of preventing the toner image from remaining on the surface of the photosensitive member when the toner image is transferred from the surface of the photosensitive member to the recording medium by the transfer unit. In addition, when the toner image is fixed on the recording medium by the fixing unit, the toner constituting the toner image is prevented from adhering to the fixing roller, and the fixing property of the toner image to the recording medium is improved. However, the wax has the property of agglomerating in the toner particles and bleeding out on the surface of the toner particles. The bleed-out wax melts and exhibits adhesiveness. For example, the bleed-out wax adheres to the surface of the photosensitive member in a film form, causes filming, and causes image defects. In addition, the toner particles are aggregated to cause image defects. In addition, since the amount of wax in the toner decreases due to the bleed-out of the wax, when the toner image is fixed on the recording medium, an offset phenomenon in which the toner adheres not to the recording medium but to the fixing roller is very likely to occur. Fixability of the image to the recording medium is reduced.

  Conventionally, a toner is manufactured by melt-kneading a binder resin, a colorant and a wax as a release agent to disperse the colorant and the release agent in the binder resin. In general, it is produced by cooling and solidifying, and mechanically pulverizing the obtained solidified product. On the other hand, recently, the chemical method has attracted attention as a method for producing toner capable of reducing the diameter of the toner, making the toner shape and the toner diameter uniform, and various proposals have been made. Typical examples of the chemical method include a melt emulsification method and a dissolution suspension method. According to the melt emulsification method, for example, a melt kneaded product of a binder resin, a colorant and a release agent and an aqueous dispersion of calcium carbonate are mixed under heating and pressure, and the melt kneaded product is emulsified in an aqueous dispersion. To obtain resin particles (toner), and by adhering calcium carbonate to the surface of the resin particles, preventing coarsening due to adhesion between the resin particles, and removing calcium carbonate on the surface after the resin particles solidify A toner manufacturing method has been proposed (see, for example, Patent Document 1). Even in the toner obtained by the melt emulsification method, the aggregation of the wax as the release agent in the toner particles and the bleed-out of the wax to the toner particle surface cannot be suppressed almost completely. As a result, filming, offset phenomenon, etc. may occur, and the fixability of toner to the recording medium may be reduced.

  Further, according to the dissolution suspension method, the toner particles are obtained by dissolving a binder resin, a colorant, a wax as a release agent, etc. in an organic solvent and suspending the obtained organic solvent solution in an aqueous medium. Manufactured. In the dissolution suspension method, a technique has been proposed in which two types of waxes having different acid values and saponification values and having melting points of 60 to 130 ° C. are used in combination as release agents (see, for example, Patent Document 2). In Example 1 described in paragraph [0073] of Patent Document 2, when a toner is produced by a dissolution suspension method, carnauba wax (melting point: 83 ° C.) and paraffin wax (melting point: 75 ° C.) are used as release agents. Are used together. However, also in the toner of Example 1, bleed out of the wax occurs. This is also clear from the fact that in Table 1 described in paragraph [0084], the toner of Example 1 is slightly wound around the fixing roller. Further, Patent Document 2 discloses that the amount ratio of the two types of wax is set in a range of 1: 4 to 7 (weight ratio), and toner offset (winding around the fixing roller) occurs outside this range. . For example, in Comparative Example 1 described in paragraph [0080], when carnauba wax and paraffin wax are used in a ratio of 1: 1 (weight ratio), the toner is wound around the fixing roller. Further, in the storability test, toner aggregation, which is considered to be accompanied by the bleed out of the wax, occurs. Thus, even if two types of waxes are used in combination in the dissolution suspension method, the bleed-out of the wax to the toner particle surface cannot be prevented. Therefore, in the technique of Patent Document 2, it is difficult to obtain a toner that hardly aggregates during storage and has excellent offset resistance, and it is inevitable that the fixing property of a toner image to a recording medium is lowered.

JP 2005-148406 A JP 2005-115186 A

  The object of the present invention is a non-temperature region in which the amount of bleed out of the wax is remarkably reduced, it has a good offset resistance, is excellent in an offset resistance particularly in a high temperature range, and prevents the occurrence of an offset phenomenon. It is an object of the present invention to provide a toner manufacturing method capable of forming a high-quality image with a high image density, having a wide offset region, excellent fixability to a recording medium, and hardly causing aggregation during storage.

  The present invention relates to a melt kneaded product of a toner material containing a binder resin, a colorant and two or more kinds of melting points of 60 to 100 ° C. (60 ° C. or more and 100 ° C. or less) and an aqueous medium containing a dispersant and water. A method for producing a toner, comprising a granulation step of preparing toner particles by mixing the mixture under heating or heating and pressurizing to form a melt kneaded product of the toner raw material.

  In the toner production method of the present invention, the wax content of two or more melting points of 60 to 100 ° C. in the melt kneaded material of the toner raw material is 1 to 10 wt% (1 wt% or more and 10 wt% or more of the total amount of the melt kneaded product). % By weight or less).

  Furthermore, the toner manufacturing method of the present invention is characterized in that the binder resin is polyester.

  Further, in the toner production method of the present invention, two or more kinds of waxes having a melting point of 60 to 100 ° C. include a wax having a polar group having a melting point of 60 to 100 ° C. and a wax having no polar group having a melting point of 60 to 100 ° C. It is characterized by doing.

  Further, in the method for producing the toner of the present invention, the wax having a polar group having a melting point of 60 to 100 ° C. has a melting point of 60 to 100 ° C. and one or more polar groups selected from an ester group, a hydroxyl group and a carboxyl group. It is characterized by being a wax having.

  Further, the toner production method of the present invention includes a wax obtained by subjecting a wax having a polar group having a melting point of 60 to 100 ° C. to a plant wax, a synthetic fatty acid ester wax, a petroleum wax, an air oxidation, a polyolefin polyol wax, and a paraffin polyol. It is characterized by being one or more selected from waxes.

  Furthermore, the toner production method of the present invention is characterized in that the wax having a polar group having a melting point of 60 to 100 ° C. is one or more selected from vegetable waxes and synthetic fatty acid ester waxes.

  Furthermore, the toner production method of the present invention is characterized in that the wax having no polar group having a melting point of 60 to 100 ° C. is one or more selected from synthetic polyolefin wax and petroleum wax.

  Furthermore, the toner production method of the present invention is characterized in that the dispersant is one or more selected from water-soluble polymer compounds.

  According to the present invention, in a melt emulsification method in which toner particles are produced by mixing a melt kneaded product of a toner raw material containing a binder resin, a colorant, a release agent and the like with an aqueous medium under heating or pressurization. By using two or more kinds of waxes having a melting point of 60 to 100 ° C. as the release agent, the wax toner particles are less likely to aggregate in the toner particles even if the total wax content is large. The amount of bleed out to the surface is significantly reduced. For this reason, it has good offset resistance, excellent offset resistance in a high temperature range, a wide non-offset area, which is a temperature range in which the occurrence of an offset phenomenon is prevented, and excellent fixability to a recording medium. Aggregation during storage hardly occurs, and a toner capable of forming a high-quality image with a high image density can be obtained. As in the present invention, the above-described remarkable effect can be obtained for the first time by the combination of the two techniques of producing the toner by the melt emulsification method and using two or more kinds of waxes having a melting point of 60 to 100 ° C. As described in the prior art, no remarkable effect can be obtained even if the dissolution suspension method is employed instead of the melt emulsification method.

  According to the present invention, the wax content on the surface of the toner particles is adjusted by setting the wax content of two or more melting points of 60 to 100 ° C. in the melt kneaded material of the toner raw material to 1 to 10% by weight of the total amount of the melt kneaded product. Since the bleed-out is kept in a small amount within a range that does not substantially impair the toner fixability, the offset resistance hardly deteriorates even in a high temperature range, and a toner with further improved fixability can be obtained.

  According to the present invention, by using polyester as the binder resin, it is possible to obtain a toner that is further excellent in offset resistance and fixability, and has extremely good color reproducibility particularly when a color toner is used.

  According to the present invention, two or more kinds of waxes having a melting point of 60 to 100 ° C are used in combination with a wax having a polar group having a melting point of 60 to 100 ° C and a wax having no polar group having a melting point of 60 to 100 ° C. Wax agglomeration in the toner particles is further prevented, and the uniform dispersion state of the wax in the toner particles is more reliably maintained, so that the amount of bleed out of the wax to the toner particle surface is further reduced, and the toner fixability Is further improved.

  According to the present invention, the wax having a melting point of 60 to 100 ° C. and having one or more polar groups selected from an ester group, a hydroxyl group and a carboxyl group is excellent in compatibility with the binder resin for toner, Since it is uniformly dispersed in the binder resin, it can be suitably used. Among these waxes, in consideration of dispersibility in the binder resin, availability, handleability and the like, vegetable wax, synthetic fatty acid ester wax, wax obtained by air oxidation of petroleum wax, polyolefin polyol wax and Those selected from paraffinic polyol waxes are preferred, and those selected from plant waxes and synthetic fatty acid ester waxes are particularly preferred.

  According to the present invention, the wax having no melting point and a polar group having a melting point of 60 to 100 ° C. selected from synthetic polyolefin wax and petroleum wax is used in combination with the aforementioned wax having a melting point of 60 to 100 ° C. and having a polar group. Are preferred. By using a specific type of wax in combination, the dispersion state of the wax in the toner particles can be improved, the aggregation of the wax can be further prevented, and the bleed-out amount can be further reduced.

  According to the present invention, by using a water-soluble polymer compound as a dispersant, the concentration of the dispersant in the aqueous medium can be easily adjusted, the dispersibility of the melt kneaded material of the toner raw material in the aqueous medium is improved, and the particle shape In addition, a toner having a uniform particle diameter can be obtained. Further, since the water-soluble polymer compound can be removed from the toner surface by a simple method such as washing with water, the process is not burdened.

  The toner production method of the present invention comprises mixing a toner raw material melt-kneaded material containing a binder resin, a colorant and two or more kinds of waxes with an aqueous solution of a dispersant under heating or heating and pressurizing to prepare a toner raw material. It includes a granulation step for generating melt-kneaded particles (toner particles). That is, the production method of the present invention is characterized in that, in the granulation step, the melt kneaded product of the toner raw material contains two or more kinds of waxes, and the other processes can be carried out in the same manner as the conventional melt emulsification method. Here, the two or more kinds of waxes are two or more kinds of waxes having different melting points of 60 to 100 ° C. This wax is used as a release agent in a conventional toner. The production method of the present invention includes, for example, a melt-kneaded material preparation step, an aqueous medium preparation step, a mixing / granulating step, a cooling drying step, and the like. In the melt-kneaded material preparation step, a melt-kneaded material of the toner raw material is prepared. In the aqueous medium preparation step, an aqueous dispersion of the dispersant is prepared. In the mixing and granulating process, the melt kneaded product of the toner raw material and an aqueous medium (aqueous dispersion of dispersant) are mixed under heating or heating and pressurization, and the molten kneaded product of the toner raw material is granulated to granulate fine particles. To do. In the cooling and drying step, the fine particles obtained in the granulation step are cooled and dried to obtain the toner of the present invention.

[Melt-kneaded preparation process]
In this step, a melt kneaded product of the toner raw material is prepared. As the toner material, a binder resin, a colorant, and two kinds of waxes (release agents) may be used, and a general toner additive such as a charge control agent may be used. The binder resin is not particularly limited as long as it can be granulated in a molten state, and binder resins commonly used in this field can be used, and examples thereof include polyester, acrylic resin, polyurethane, and epoxy resin. Known polyesters can be used, and examples thereof include polycondensates of polybasic acids and polyhydric alcohols. As the polybasic acid, those known as polyester monomers can be used, for example, terephthalic acid, isophthalic acid, phthalic anhydride, trimellitic anhydride, pyromellitic acid, naphthalenedicarboxylic acid and other aromatic carboxylic acids, maleic anhydride Examples thereof include aliphatic carboxylic acids such as acid, fumaric acid, succinic acid, alkenyl succinic anhydride, and adipic acid, and methyl esterified products of these polybasic acids. A polybasic acid can be used individually by 1 type, or can use 2 or more types together. As the polyhydric alcohol, those known as polyester monomers can be used. For example, aliphatic polyhydric alcohols such as ethylene glycol, propylene glycol, butanediol, hexanediol, neopentylglycol, glycerin, cyclohexanediol, cyclohexanedimethanol And aromatic diols such as alicyclic polyhydric alcohols such as hydrogenated bisphenol A, ethylene oxide adducts of bisphenol A, propylene oxide adducts of bisphenol A, and the like. A polyhydric alcohol can be used individually by 1 type, or can use 2 or more types together. The polycondensation reaction between the polybasic acid and the polyhydric alcohol can be carried out according to a conventional method. For example, the polybasic acid and the polyhydric alcohol are contacted in the presence or absence of an organic solvent and in the presence of a polycondensation catalyst. The process is terminated when the acid value, softening point, etc. of the polyester to be produced reach a predetermined value. Thereby, polyester is obtained. When a methyl esterified product of a polybasic acid is used as a part of the polybasic acid, a demethanol polycondensation reaction is performed. In this polycondensation reaction, for example, the carboxyl group content at the end of the polyester can be adjusted by appropriately changing the mixing ratio of polybasic acid and polyhydric alcohol, the reaction rate, etc., and thus the properties of the resulting polyester are modified. it can. Further, when trimellitic anhydride is used as the polybasic acid, a modified polyester can be obtained also by easily introducing a carboxyl group into the main chain of the polyester. Although it does not restrict | limit especially as an acrylic resin, An acidic group containing acrylic resin can be used preferably. The acidic group-containing acrylic resin is, for example, an acrylic resin monomer or an acrylic resin monomer containing an acidic group or a hydrophilic group and / or a vinyl having an acidic group or a hydrophilic group when an acrylic resin monomer or an acrylic resin monomer and a vinyl monomer are polymerized. It can manufacture by using a system monomer together. Known acrylic resin monomers can be used, for example, acrylic acid that may have a substituent, methacrylic acid that may have a substituent, acrylic ester that may have a substituent, and a substituent. Methacrylic acid ester and the like. Acrylic resin monomers can be used alone or in combination of two or more. As the vinyl monomer, known monomers can be used, and examples thereof include styrene, α-methylstyrene, vinyl bromide, vinyl chloride, vinyl acetate, acrylonitrile and methacrylonitrile. A vinyl monomer can be used individually by 1 type, or can use 2 or more types together. The polymerization is performed by solution polymerization, suspension polymerization, emulsion polymerization, or the like using a general radical initiator. Although it does not restrict | limit especially as a polyurethane, For example, an acidic group or a basic group containing polyurethane can be used preferably. The acidic group or basic group-containing polyurethane can be produced according to a known method. For example, an acid group or basic group-containing diol, polyol and polyisocyanate may be subjected to addition polymerization. Examples of the acidic group or basic group-containing diol include dimethylolpropionic acid and N-methyldiethanolamine. Examples of the polyol include polyether polyols such as polyethylene glycol, polyester polyols, acrylic polyols, and polybutadiene polyols. Examples of the polyisocyanate include tolylene diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate. Each of these components can be used alone or in combination of two or more. Although it does not restrict | limit especially as an epoxy resin, An acidic group or a basic group containing epoxy resin can be used preferably. An acidic group or basic group-containing epoxy resin is produced, for example, by adding or addition polymerizing a base epoxy resin with a polycarboxylic acid such as adipic acid and trimellitic anhydride or an amine such as dibutylamine or ethylenediamine. be able to. Among these binder resins, polyester is preferable. Polyester is excellent in transparency, and can impart good powder fluidity, low-temperature fixability, secondary color reproducibility and the like to the obtained toner particles, and is therefore suitable as a binder resin for color toners. Further, polyester and acrylic resin may be grafted. Among these binder resins, the softening point is 150 ° C. or lower in consideration of easy granulation operation, kneadability with a colorant, and uniform shape and size of the toner particles obtained. The binder resin having a softening point of 60 to 150 ° C. is particularly preferable. Among them, a binder resin having a weight average molecular weight of 5,000 to 500,000 is preferable. Binder resins can be used alone or in combination of two or more different types. Furthermore, even if it is the same resin, multiple types which are different in any or all of molecular weight, monomer composition, etc. can be used.

  As the colorant, organic dyes, organic pigments, inorganic dyes, inorganic pigments and the like commonly used in the electrophotographic field can be used. Examples of the black colorant include carbon black, copper oxide, manganese dioxide, aniline black, activated carbon, nonmagnetic ferrite, magnetic ferrite, and magnetite. Examples of yellow colorants include chrome lead, zinc yellow, cadmium yellow, yellow iron oxide, mineral fast yellow, nickel titanium yellow, navel yellow, naphthol yellow S, Hansa yellow G, Hansa yellow 10G, benzidine yellow G, and benzidine. Yellow GR, Quinoline Yellow Lake, Permanent Yellow NCG, Tartrazine Lake, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94 and C.I. I. Pigment yellow 138, and the like. Examples of the orange colorant include red chrome yellow, molybdenum orange, permanent orange GTR, pyrazolone orange, vulcan orange, indanthrene brilliant orange RK, benzidine orange G, indanthrene brilliant orange GK, C.I. I. Pigment orange 31 and C.I. I. And CI Pigment Orange 43. Examples of red colorants include bengara, cadmium red, red lead, mercury sulfide, cadmium, permanent red 4R, risol red, pyrazolone red, watching red, calcium salt, lake red C, lake red D, and brilliant carmine 6B. Eosin Lake, Rhodamine Lake B, Alizarin Lake, Brilliant Carmine 3B, C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 178 and C.I. I. And CI Pigment Red 222. Examples of purple colorants include manganese purple, fast violet B, and methyl violet lake. Examples of blue colorants include bitumen, cobalt blue, alkali blue lake, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, phthalocyanine blue partially chlorinated products, first sky blue, induslen blue BC, C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 16 and C.I. I. And CI Pigment Blue 60. Examples of the green colorant include chrome green, chromium oxide, pigment green B, micalite green lake, final yellow green G, and C.I. I. And CI Pigment Green 7. Examples of the white colorant include compounds such as zinc white, titanium oxide, antimony white, and zinc sulfide. One colorant can be used alone, or two or more different colorants can be used in combination. Moreover, even if it is the same color, 2 or more types can be used together. The content of the colorant in the melt kneaded product of the toner raw material is not particularly limited, but is preferably 0.1 to 20% by weight, more preferably 0.2 to 10% by weight of the total amount of the melt kneaded product.

  As the wax, two or more kinds of waxes having a melting point of 60 to 100 ° C., preferably 70 to 100 ° C., are selected and used. It is preferable to use two or more waxes having melting points in the above range and different melting points. When the melting point of the wax is within the above range, the resulting toner can be provided with good storage stability and resistance to offset on the low temperature side. When the melting point is less than 60 ° C., the storage stability of the obtained toner is lowered, and toner particles may aggregate in the image forming apparatus, particularly in the developing tank, which may cause image defects. When the melting point exceeds 100 ° C., when the toner image is fixed on the recording medium under heating in the fixing unit, the wax may not be sufficiently melted and low temperature offset may occur. Two or more kinds of waxes having a melting point of 60 to 100 ° C. are a wax having a polar group having a melting point of 60 to 100 ° C. (hereinafter referred to as “polar wax” unless otherwise specified), and a melting point of 60 to 100 ° C. It is preferable to include a wax having no polar group (hereinafter referred to as “non-polar wax” unless otherwise specified). “Non-polar wax” means not having polarity at all, but having no polar group. Although it will not restrict | limit especially if it is a functional group which has polarity as a polar group in polar wax, For example, an ester group, a carboxy group, a hydroxyl group etc. are preferable. Polar waxes can have one or more polar groups. As specific examples of polar waxes having ester groups, known ones can be used. For example, plant waxes such as carnauba wax, rice wax, candelilla wax, reaction of linear saturated fatty acids with monohydric or polyhydric alcohols Examples thereof include synthetic fatty acid ester waxes. Known polar waxes having a carboxy group can be used, for example, wax obtained by air oxidation of low molecular weight polyolefin wax (polypropylene wax, polyethylene wax, etc.), wax obtained by air oxidation of paraffin wax, and the like. Can be mentioned. Known polar waxes having a hydroxyl group can be used, and examples thereof include low molecular weight polyolefin polyols and paraffin polyols. Among these, polar waxes having ester groups are preferred. A polar wax can be used individually by 1 type, or can use 2 or more types together. Known non-polar waxes can be used, and examples thereof include synthetic polyolefin waxes such as polyethylene wax and polypropylene wax, and petroleum waxes such as paraffin wax. A nonpolar wax can be used individually by 1 type, or can use 2 or more types together. Preferable combinations of polar wax and nonpolar wax include plant wax and synthetic polyolefin wax, plant wax and petroleum wax, synthetic fatty acid ester wax and synthetic polyolefin wax, synthetic fatty acid ester wax and petroleum wax. More preferable combinations of polar wax and nonpolar wax include carnauba wax and paraffin wax, carnauba wax and polyethylene wax, linear saturated fatty acid ester and paraffin wax, linear saturated fatty acid ester and polyethylene wax, and the like. The use ratio of the polar wax and the nonpolar wax is not particularly limited and can be appropriately selected from a wide range. However, the use amount of the polar wax is preferably 20 to 80% by weight, more preferably 40 to 60% by weight based on the total amount of the wax. Yes, the balance being nonpolar wax. The wax content that is the total amount of two or more kinds of waxes in the melt kneaded material of the toner raw material is not particularly limited and can be appropriately selected from a wide range, but is preferably 1 to 10% by weight of the total amount of the melt kneaded material, more preferably Is 5 to 8% by weight. When the wax content is within the above range, a toner having good offset resistance, excellent fixability, and no filming or aggregation between toners can be obtained. When the wax content is less than 1% by weight, the properties as a release agent are not sufficiently exhibited, and an offset phenomenon on the high temperature side may occur. If the wax content exceeds 10% by weight, filming may occur in which the wax bleed out on the surface of the toner particles adheres to the surface of the photoreceptor in a film form.

  As the charge control agent, those for positive charge control and negative charge control commonly used in this field can be used. Examples of charge control agents for controlling positive charge include nigrosine dyes, basic dyes, quaternary ammonium salts, quaternary phosphonium salts, aminopyrines, pyrimidine compounds, polynuclear polyamino compounds, aminosilanes, nigrosine dyes and derivatives thereof, and triphenylmethane. Derivatives, guanidine salts, amidine salts and the like can be mentioned. Charge control agents for controlling negative charges include oil-soluble dyes such as oil black and spiron black, metal-containing azo compounds, azo complex dyes, metal salts of naphthenic acid, metal salts of salicylic acid and its derivatives (metals are metal Chromium, zinc, zirconium, etc.), fatty acid soaps, long-chain alkyl carboxylates, resin acid soaps, and the like. A charge control agent can be used individually by 1 type, or can use 2 or more types together as needed. The content of the charge control agent in the melt kneaded material of the toner material is not particularly limited and can be appropriately selected from a wide range, but is preferably 0.5 to 3% by weight of the total amount of the melt kneaded material.

  A preferable form of the melt-kneaded material of the toner raw material includes 0.1 to 20% by weight of a colorant and 1 to 10% by weight of a wax, the balance being a binder resin, 0.1 to 20% by weight of a colorant, and a wax Examples include a form containing 1 to 10% by weight and charge control agent 0.5 to 3% by weight, with the balance being a binder resin. The toner raw material is melt-kneaded, for example, by dry-mixing the toner raw material with a mixer and melt-kneading the resulting mixture with a kneader. The melt kneading is performed while heating to a temperature equal to or higher than the melting temperature of the binder resin (usually about 80 to 200 ° C., preferably about 100 to 150 ° C.). Here, a known mixer can be used. For example, Henschel mixer (trade name, manufactured by Mitsui Mining Co., Ltd.), super mixer (trade name, manufactured by Kawata Co., Ltd.), Mechano Mill (trade name, Okada Seiko (trade name) Henschel type mixing devices such as HONSHELL type (trade name, manufactured by Hosokawa Micron Co., Ltd.), hybridization system (trade name, manufactured by Nara Machinery Co., Ltd.), Cosmo system (trade name, Kawasaki Heavy Industries, Ltd.) ))). A well-known thing can be used also as a kneading machine, for example, common kneading machines, such as a twin-screw extruder, a 3 roll, a laboratory blast mill, can be used. More specifically, for example, a uniaxial or biaxial extruder such as TEM-100B (trade name, manufactured by Toshiba Machine Co., Ltd.), PCM-65 / 87 (trade name, manufactured by Ikegai Co., Ltd.), knee An open roll type such as Dix (trade name, manufactured by Mitsui Mining Co., Ltd.) can be used. Of the toner raw materials, a coloring agent, wax, etc. are granulated to form composite particles having a desired particle diameter, and the composite particles, a binder resin, a charge control agent, and the like are dry-mixed with a mixer to obtain a toner raw material. May be prepared. The composite particles can be obtained, for example, by adding an appropriate amount of water, lower alcohol or the like to a colorant, wax, etc., granulating with a general granulator such as a high speed mill, and drying.

[Aqueous medium preparation step]
In this step, an aqueous medium that is an aqueous dispersion or aqueous solution of a dispersant is prepared. The aqueous medium is prepared, for example, by dissolving or dispersing the dispersant in water. As the dispersant, those commonly used in this field can be used, and examples thereof include metal hydroxides and water-soluble polymer compounds. Examples of the metal hydroxide include aluminum hydroxide, magnesium hydroxide, and ferric hydroxide. Examples of the water-soluble polymer compound include acrylic monomers such as (meth) acrylic acid, α-cyanoacrylic acid, α-cyanomethacrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid, and maleic anhydride. , Β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate, β-hydroxypropyl acrylate, β-hydroxypropyl methacrylate, γ-hydroxypropyl acrylate, γ-hydroxypropyl methacrylate, 3-chloro-2 acrylate -Hydroxypropyl-containing acrylic monomers such as hydroxypropyl and 3-chloro-2-hydroxypropyl methacrylate, diethylene glycol monoacrylate, diethylene glycol monomethacrylate, glycerol monoacrylate, glycerol monomethacrylate Ester monomers such as esters, vinyl alcohol monomers such as N-methylol acrylamide and N-methylol methacrylamide, ethers with vinyl alcohol, vinyl alkyl such as vinyl methyl ether, vinyl ethyl ether, and vinyl propyl ether Ether monomers, vinyl alkyl ester monomers such as vinyl acetate, vinyl propionate and vinyl butyrate, aromatic vinyl monomers such as styrene, α-methyl styrene and vinyl toluene, acrylamide, methacrylamide, di Acetone acrylamide, amide monomers such as these methylol compounds, nitrile monomers such as acrylonitrile and methacrylonitrile, acid chloride monomers such as acrylic acid chloride and methacrylic acid chloride, vinyl pyridine, One or two selected from vinyl nitrogen-containing heterocyclic monomers such as nylpyrrolidone, vinylimidazole and ethyleneimine, and crosslinkable monomers such as ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, allyl methacrylate and divinylbenzene (Meth) acrylic polymers containing various hydrophilic monomers, polyvinyl alcohol, methylcellulose, gelatin, polyoxyethylene, polyoxypropylene, polyoxyethylene alkylamine, polyoxypropylene alkylamine, polyoxyethylene alkylamide, poly Oxypropylene alkylamide, polyoxyethylene nonylphenyl ether, polyoxyethylene lauryl phenyl ether, polyoxyethylene stearyl phenyl ester, polyoxy Polyoxyethylene polymers such as ethylene nonyl phenyl ester, cellulose polymers such as methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, polyoxyethylene lauryl phenyl ether sodium sulfate, polyoxyethylene lauryl phenyl ether potassium sulfate, polyoxyethylene nonyl phenyl ether Polyoxyalkylene alkyl such as sodium sulfate, sodium polyoxyethylene oleyl phenyl ether sulfate, sodium polyoxyethylene cetyl phenyl ether sulfate, polyoxyethylene lauryl phenyl ether ammonium sulfate, polyoxyethylene nonylphenyl ether ammonium sulfate, polyoxyethylene oleyl phenyl ether ammonium sulfate Ant Ruether sulfate, sodium polyoxyethylene lauryl ether sulfate, potassium polyoxyethylene lauryl ether sulfate, sodium polyoxyethylene oleyl ether sulfate, sodium polyoxyethylene cetyl ether sulfate, ammonium polyoxyethylene lauryl ether sulfate, ammonium polyoxyethylene oleyl ether sulfate And polyoxyalkylene alkyl ether sulfates. Among these dispersants, water-soluble polymer compounds are preferable, and anionic water-soluble polymer compounds are particularly preferable. The anionic water-soluble polymer compound has a particularly high solubility in water among water-soluble polymer compounds, so that it is easy to adjust the concentration of the polymer compound in the aqueous medium, and the dispersion of the melt-kneaded material in the aqueous medium is facilitated. The toner is further improved in the properties and the shape and particle diameter are uniform. A dispersing agent can be used individually by 1 type, or can use 2 or more types together. The amount of the dispersant used is not particularly limited, but is preferably 0.05 to 10% by weight, more preferably 0.1 to 5% by weight based on the total amount of water and the dispersant.

  The water in which the dispersant is dissolved or dispersed preferably has a conductivity of 20 μS / cm or less, and particularly preferably 10 μS / cm. Such water can be obtained, for example, by an activated carbon method, an ion exchange method, a distillation method, a reverse osmosis method, or the like. Of course, water may be prepared by combining two or more of these methods. Equipment for producing water with low electrical conductivity is commercially available, and examples include ultrapure water production equipment (trade name: Minipure TW-300RU, manufactured by Nomura Micro Science Co., Ltd.). The conductivity of water can be measured using, for example, a Lacom tester conductivity meter CON110 (trade name, manufactured by AS ONE Corporation). Dissolution or dispersion of the dispersant in water is performed, for example, by mixing a predetermined amount of the dispersant with water. For the mixing, the same mixer as that used for mixing the toner raw materials can be used.

[Mixing and granulation process]
In this step, the melt kneaded product of the toner raw material and an aqueous medium are mixed and stirred under heating or heating and pressurization to granulate the melt kneaded product to obtain an aqueous dispersion of melt kneaded product particles. The heating temperature at the time of stirring and mixing the melt-kneaded product and the aqueous medium is not particularly limited, and the type and characteristics (weight average molecular weight, softening point) of the binder resin contained in the melt-kneaded product are finally obtained. The temperature can be appropriately selected from a wide range depending on the particle size of the toner particles to be processed, but preferably is a temperature higher than the softening point of the binder resin contained in the melt-kneaded product, more preferably the softening point of the binder resin to the binder. This is the range of the thermal decomposition temperature of the resin. Further, the stirring speed at the time of heating is not particularly limited, and the stirring operation can be smoothly carried out according to the kind and content of the binder resin, colorant and other additives in the melt-kneaded product, and desired particles. What is necessary is just to select suitably the stirring speed which can obtain the melt-kneaded particle | grains which have a diameter, a particle size distribution, and a shape. Also, the stirring time during heating is not particularly limited, and a wide range depending on various conditions such as the type and content of the binder resin, the colorant and other additives, the type and concentration of the dispersant in the melt-kneaded product. Can be selected as appropriate. Mixing of the melt-kneaded product and the aqueous medium is preferably performed under pressure. By performing mixing under pressure, the melt-kneaded particles can be further reduced in diameter. The pressurization is performed, for example, in a pressure-resistant sealed container. The mixing ratio of the melt-kneaded material and the aqueous medium is not particularly limited, and can be appropriately selected from a wide range according to various conditions such as the content of the binder resin and the content of the dispersant in the melt-kneaded material. From the viewpoint of efficiently carrying out the subsequent washing operation of the melt-kneaded particles, the isolation operation of the melt-kneaded particles and the like, the aqueous medium is added in an amount of 100 to 500 wt. It is preferable to use about parts.

  Specifically, mixing of the melt-kneaded material and the aqueous medium is performed using a mixer such as a general emulsifier and a disperser. As such a mixer, the melt-kneaded product and the aqueous medium can be received in a batch type or a continuous type, and have a heating means and, if necessary, a pressurizing means. It is preferable to use an apparatus capable of producing melt-kneaded particles by mixing under heating or heating and pressurizing, and discharging the mixture containing the melt-kneaded particles in a batch or continuous manner. The mixer is required to have a stirring means and be capable of mixing the melt-kneaded product and the aqueous medium with stirring. Moreover, it is preferable that a mixer has a container for mixing a melt-kneaded material and an aqueous medium, and this container has a temperature adjustment means with a heating means. The container preferably has pressure resistance, and more preferably has pressure resistance and is provided with a pressure adjusting means (such as a pressure adjusting valve). If such a container is used, the temperature of the mixture in the container is kept substantially constant, and the pressure in the container is controlled to be substantially constant in consideration of the softening point of the binder resin and the vapor pressure of the aqueous medium. Moreover, when mixing a melt-kneaded material and an aqueous medium under the temperature of 100 degreeC or more, it is preferable to use the mixer which is equipped with a mechanical seal and is a pressure-resistant container which can seal a container. Such mixers are commercially available. Specific examples thereof include Ultra Tarrax (trade name, manufactured by IKA Japan), Polytron Homogenizer (trade name, manufactured by KINEMATICA), T. K. Batch type emulsifiers such as auto homomixer (trade name, manufactured by Special Machine Industries Co., Ltd.), Ebara Milder (trade name, manufactured by Ebara Corporation), T. K. Pipeline homomixer, T.W. K. Homomic line flow, T.W. K. Filmix (trade name, manufactured by Tokushu Kika Kogyo Co., Ltd.), colloid mill (trade name, manufactured by Shinko Pantech Co., Ltd.), slasher, trigonal wet pulverizer (trade name, manufactured by Mitsui Miike Chemical Co., Ltd.) ), Continuous emulsifiers such as Cavitron (trade name, manufactured by Eurotech Co., Ltd.), Fine Flow Mill (trade name, manufactured by Taiheiyo Kiko Co., Ltd.), Claremix (trade name, manufactured by M Technique Co., Ltd.) , Fillmix (trade name, manufactured by Tokushu Kika Kogyo Co., Ltd.) and the like.

  When melt-kneaded particles are produced in this step, this step is performed under heating, and the produced melt-kneaded particles are in a molten state and exhibit adhesiveness. Are likely to adhere to each other and become coarse. However, since a dispersant is present in the mixture and the melt-kneaded particles are stabilized by the dispersant, coarsening due to reaggregation of the melt-kneaded particles does not occur. The same applies to the next cooling and drying step.

[Cooling drying process]
In this step, the slurry containing the melt-kneaded particles (hereinafter referred to as “melt-kneaded particle-containing slurry”) is cooled, the melt-kneaded particles are taken out from the melt-kneaded particle-containing slurry, washed, and then melt-kneaded. The toner of the present invention is obtained by drying the product particles. Cooling of the melt-kneaded product particle-containing slurry is performed by forcibly cooling using a refrigerant or the like or by natural cooling (cooling) after stopping heating in the granulation step. Cooling is preferably performed with stirring. Thereby, the stabilizing effect of the melt-kneaded particles by the dispersant is sufficiently exhibited, and coarsening due to re-aggregation of the melt-kneaded particles in the cooling step can be prevented. Further, when the granulation step is performed under pressure, it is preferable to continue the pressure even in the cooling step. When the granulation step is performed under pressure and the pressurization is stopped in the cooling step and released to atmospheric pressure, the melt-kneaded particle-containing slurry bumps and bubbles are generated, and the melt-kneaded particles become coarse, The subsequent operations such as washing and drying cannot be performed efficiently. The pressure in the mixing system is preferably returned to atmospheric pressure when the temperature of the slurry containing the melt-kneaded particles is 50 ° C. or lower, preferably room temperature (about 25 ° C.) by forced cooling or natural cooling. By cooling, the melt-kneaded particles are solidified to produce toner particles, and a slurry containing toner particles (hereinafter referred to as “toner particle-containing slurry”) is obtained. Next, washing is performed to remove impurities derived from the dispersant. The washing is performed, for example, by repeatedly performing a water washing operation of isolating the toner particles from the toner particle-containing slurry and mixing the toner particles with water to isolate the toner particles. In isolating the toner particles from the toner particle-containing slurry and the mixture of the toner particles and water, general solid-liquid separation means such as filtration, suction filtration, and centrifugal separation can be employed. The water mixed with the toner particles is preferably washing water having a conductivity of 20 μS / cm or less. Such washing water can be prepared, for example, by an activated carbon method, an ion exchange method, a distillation method, a reverse osmosis method, or the like. Moreover, you may prepare washing water combining 2 or more types among these methods. The temperature of the washing water is not particularly limited, but is preferably about 10 to 80 ° C. The washing operation may be carried out either batchwise or continuously. The washing operation is repeated until the conductivity of the washing water after the toner particles are mixed and the toner particles are isolated is preferably 100 μS / cm or less, more preferably 10 μS / cm or less. . Although the number of washings and the amount of washing water to be used vary depending on the concentration of the dispersing agent and the amount of treatment before washing, the amount of the dispersing agent to be used can be reduced according to the present invention, so that the washing operation can be reduced. After the cleaning, the toner particles of the present invention are obtained by drying the toner particles. Any general drying means can be employed for drying, and examples thereof include an airflow drying method, a vacuum drying method, and a natural drying method. According to the present invention, it is possible to reduce the particle diameter to about 5 μm, and it is possible to easily manufacture a toner having a uniform particle size distribution narrower than that of a conventional toner.

  The toner of the present invention is used by mixing with a general external additive as necessary. Known external additives can be used, and examples thereof include fluidity improvers such as silicon oxide, titanium oxide, silicon carbide, aluminum oxide, and barium titanate. A fluidity improver can be used individually by 1 type, or can use 2 or more types together. The amount of the fluidity improver used is not particularly limited, but is preferably 0.1 to 3.0 parts by weight with respect to 100 parts by weight of the toner of the present invention.

The toner of the present invention can be used as it is as a one-component developer or as a two-component developer mixed with a carrier. As the carrier, known magnetic particles can be used. Specific examples of the magnetic particles include metals such as iron, ferrite and magnetite, and alloys of these metals with metals such as aluminum and lead. Among these, ferrite is preferable. A resin layer may be provided on the surface of the carrier. Examples of the synthetic resin used for the resin layer include olefin resins, styrene resins, styrene / acrylic resins, silicone resins, ester resins, fluorine-containing polymer resins, and the like. Although the particle size of the carrier is not particularly limited, it is preferably 30 to 50 μm in consideration of high image quality. The use ratio of the toner and the carrier in the two-component developer is not particularly limited and can be appropriately selected according to the type of the toner and the carrier. However, if the resin-coated carrier (density 5 to 8 g / cm ² ) is taken as an example, The toner may be used so that the developer contains 2 to 30% by weight, preferably 2 to 20% by weight of the total amount of the developer.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. In the following, “parts” and “%” respectively represent “parts by weight” and “% by weight” unless otherwise specified.

[Preparation of water]
In the following Examples and Comparative Examples, water having an electrical conductivity of 0.5 μS / cm was used as water for preparing an aqueous medium and water for cleaning toner particles. This washing water was prepared from tap water using an ultrapure water production apparatus (trade name: Minipure TW-300RU, manufactured by Nomura Micro Science Co., Ltd.). The conductivity of water was measured using a Lacom Tester conductivity meter CON110 (trade name, manufactured by AS ONE Corporation).

[Volume average particle size and coefficient of variation]
The volume average particle diameter of the toner particles was calculated from the measured values with a measurement particle number of 50000 count and an aperture diameter of 100 μm using Coulter Multisizer II (trade name, manufactured by Beckman Coulter, Inc.). The coefficient of variation was calculated from the following formula (1) based on the volume average particle diameter and its standard deviation.
Coefficient of variation = standard deviation / volume average particle diameter (1)

[Softening point of binder resin]
The softening point of the binder resin is obtained by extruding a sample 1g from a die (nozzle) having a diameter of 1 mm and a length of 1 mm using a flow characteristic evaluation apparatus (trade name: Flow Tester CFT-100C, manufactured by Shimadzu Corporation). In this way, while applying a load of 10 kgf / cm ² (9.8 × 10 ⁵ Pa), heating was performed at a temperature rising rate of 6 ° C. per minute, and the temperature when half of the sample flowed out from the die was obtained.

[Glass transition point of binder resin (Tg)]
The glass transition point (Tg) of the binder resin was measured using a differential scanning calorimeter (trade name: DSC220, manufactured by Seiko Denshi Kogyo Co., Ltd.) according to Japanese Industrial Standard (JIS) K7121-1987. The DSC curve is measured by heating at a rate of 10 ° C. per minute, and a straight line obtained by extending the base line on the high temperature side of the endothermic peak corresponding to the glass transition of the obtained DSC curve to the low temperature side, from the peak rising part to the peak The temperature at the point of intersection with the tangent drawn at the point where the slope is maximum with respect to the curve is obtained.

[Melting point of wax]
The melting point of the wax was measured by using a differential scanning calorimeter (DSC220) and heating the sample 1 g from 20 ° C. to 150 ° C. at a heating rate of 10 ° C. per minute and then rapidly cooling from 150 ° C. to 20 ° C. twice. Repeatedly, it was determined as the temperature at the apex of the endothermic peak corresponding to the melting of the DSC curve obtained by the second operation.

[Residual ratio of wax]
The residual ratio of the wax was determined as a percentage (%) of the wax content in the toner particles with respect to the wax content in the raw material. The wax content in the toner particles is determined by using a differential scanning calorimeter (DSC220) to determine the endothermic peak area attributed to the wax, that is, the endothermic amount of the wax in the toner particles, and the content of the wax and the toner as the measurement sample. It was determined by comparing the amount.

Example 1
[Melting and kneading process]
220 parts of polyoxypropylene (2.0) -2,2-bis (4-hydroxyphenyl) propane, 90 parts of polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane and terephthalic acid Polyester resin synthesized using 200 parts as a raw material monomer and 3 parts of dibutyltin oxide as a catalyst (glass transition point (Tg) 62 ° C., softening point 120 ° C., binder resin, acid value 15 mg / KOH) and copper phthalocyanine (C.I. Pigment Blue 15: 3, colorant) was melt-kneaded in a kneader at a temperature of 140 ° C. for 40 minutes to prepare a master batch having a colorant concentration of 40%. Here, polyoxypropylene (2.0) -2,2-bis (4-hydroxyphenyl) propane refers to propylene oxide with respect to 1.0 mol of 2,2-bis (4-hydroxyphenyl) propane. It is a compound added with an average of 2.0 moles. Polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane is an average of 2 ethylene oxides per 1.0 mol of 2,2-bis (4-hydroxyphenyl) propane. This is a compound added with 0.0 mol.

  Next, 79.5 parts of the same polyester resin used for the preparation of the masterbatch, 12.5 parts of the masterbatch (colorant concentration 40%) obtained above, 3 parts of paraffin wax (melting point 72 ° C.), carnauba 3 parts of wax (melting point: 85 ° C.) and 2 parts of a charge control agent (trade name: TN105, Hodogaya Chemical Co., Ltd.) were mixed and dispersed for 3 minutes with a Henschel mixer to obtain a toner raw material. Using the obtained toner raw material, a twin-screw extruder (trade name: PCM-30, manufactured by Ikegai Co., Ltd.), a cylinder set temperature of 110 ° C., a barrel rotation speed of 300 rotations per minute (300 rpm), a raw material supply speed of 20 kg / The mixture was melt kneaded and dispersed under operating conditions for a time to prepare a melt kneaded product.

[Aqueous medium preparation step]
Ammonium salt of styrene-α-methylstyrene-acrylic acid copolymer (dispersing agent, water-soluble polymer compound, trade name: Jonkrill 61J, manufactured by Johnson Polymer Co., Ltd.) 100 parts and water 900 parts are mixed and dispersed. An aqueous medium having an agent concentration of 10% was prepared.

[Granulation process]
100 parts of the melt-kneaded product obtained above and 550 parts of an aqueous medium (dispersant concentration 10%) are put into a metal mixing vessel equipped with a pressure regulating valve, heating means and rotor-stator stirring means (diameter 30 mm). The mixture was stirred and mixed for 10 minutes under a pressure of 5 atm and heated at 120 ° C. to produce toner particles. The rotor rotation speed of the rotor-stator stirring means was 14000 rotations per minute.

[Cooling drying process]
After the toner particles were generated, heating was stopped, and the slurry containing the generated toner particles was cooled with stirring until the liquid temperature reached 20 ° C. The stirring speed (rotor rotational speed) was 14,000 revolutions per minute. To this slurry, water having a conductivity of 0.5 μS / cm (water temperature 20 ° C.) was added to wash the toner particles. To clean the toner particles, water (conductivity 0.5 μS / cm) is added to the slurry, the solid content is adjusted to 10% depending on the amount of water added, and the stirring blade is rotated using a turbine-type stirring blade. It was performed by stirring for 30 minutes at a speed of 300 revolutions per minute. This washing operation was repeated until the conductivity of the supernatant liquid separated from the stirred slurry by centrifugation was 10 μS / cm or less. A solid content including toner particles was separated from the washed slurry by centrifugation. The collected solid content was lyophilized to obtain toner particles. The obtained toner particles had a volume average particle size of 6.8 μm and a coefficient of variation of 32. 100 parts of the obtained toner particles were mixed with 0.7 part of silica particles having an average primary particle diameter of 20 nm that had been hydrophobized with a silane coupling agent and 1 part of titanium oxide to produce the toner of the present invention.

(Example 2)
A toner of Example 2 was prepared in the same manner as in Example 1 except that 3 parts of polyethylene wax (melting point: 99 ° C.) and 3 parts of carnauba wax (melting point: 85 ° C.) were used. The toner particles of Example 2 had a volume average particle diameter of 7.0 μm and a coefficient of variation of 32.

(Example 3)
A toner of Example 3 was prepared in the same manner as in Example 1 except that 3 parts of paraffin wax (melting point: 72 ° C.) and 3 parts of fatty acid ester (melting point: 80 ° C.) were used. The toner particles of Example 3 had a volume average particle size of 6.8 μm and a coefficient of variation of 33.

Example 4
A toner of Example 3 was prepared in the same manner as in Example 1 except that 3 parts of polyethylene wax (melting point: 99 ° C.) and 3 parts of fatty acid ester (melting point: 80 ° C.) were used. The volume average particle diameter of the toner particles of Example 3 is 7.0 μm, and the coefficient of variation is 32.

(Comparative Example 1)
A toner of Comparative Example 1 was produced in the same manner as in Example 1 except that 6 parts of paraffin wax (melting point: 72 ° C.) was used as the wax. The volume average particle diameter of the toner particles of Comparative Example 1 was 6.5 μm, and the coefficient of variation was 31.

(Comparative Example 2)
A toner of Comparative Example 2 was produced in the same manner as in Example 1 except that 6 parts of carnauba wax (melting point: 85 ° C.) was used as the wax. The volume average particle size of the toner particles of Comparative Example 2 was 6.3 μm, and the coefficient of variation was 33.

(Comparative Example 3)
A toner of Comparative Example 3 was produced in the same manner as in Example 1 except that 6 parts of fatty acid ester wax (melting point: 80 ° C.) was used as the wax. The toner particles of Comparative Example 3 had a volume average particle size of 6.5 μm and a coefficient of variation of 32.

(Comparative Example 4)
A toner of Comparative Example 4 was produced in the same manner as in Example 1 except that 6 parts of polyethylene wax (melting point: 99 ° C.) was used as the wax. The volume average particle size of the toner particles of Comparative Example 4 was 7.0 μm, and the coefficient of variation was 33.

(Test Example 1)
For the toners obtained in Examples 1 to 4 and Comparative Examples 1 to 4, a ferrite core carrier having a volume average particle size of 60 μm was adjusted as a carrier so that the toner concentration was 4% of the total amount of the toner and the carrier. To prepare a two-component developer having a toner concentration of 4%. The following evaluation was performed on the obtained two-component developer.

[Formation of image for evaluation]
The obtained two-component developer was put into a developing device of a test printer obtained by removing a fixing device from a commercially available printer (trade name: LIBRE AR-S505, manufactured by Sharp Corporation). JIS) Adjusted so that the toner adhesion amount is 0.6 mg / cm ² on the A4 size recording paper defined in P0138, and the rectangular solid image portion of 20 mm in length and 50 mm in width is unfixed. Formed with. An unfixed toner image formed was fixed by using an external fixing machine at a recording paper passing speed of 120 mm / sec (120 mm / sec) to form an evaluation image. For the external fixing machine, an oilless type fixing device taken out from a commercially available full-color copying machine (trade name: LIBRE AR-C260, manufactured by Sharp Corporation) can be set to an arbitrary value for the surface temperature of the heating roller. I used a modified version. Here, the oilless type fixing device is a fixing device that performs fixing without applying wax such as silicone oil to the heating roller.

[High temperature offset resistance evaluation]
Whether or not the high temperature offset phenomenon occurred was determined by visually observing whether or not the toner image was re-transferred from the heating roller to the white background portion of the recording paper that should be the white background of the recording paper. This operation is repeated by sequentially increasing the surface temperature of the heating roller from 100 ° C. to 210 ° C. in increments of 5 ° C., and the maximum temperature of the heating roller surface temperature (hereinafter referred to as the maximum fixing temperature) at which no high temperature offset phenomenon occurs. Asked. In the evaluation of the high temperature offset resistance, the case where the maximum fixing temperature was 200 ° C. or higher was evaluated as good (◯), and the case where the maximum fixing temperature was less than 200 ° C. was evaluated as defective (×).

[Non-offset evaluation]
Similarly to the evaluation of the high temperature offset resistance, the surface temperature of the heating roller is sequentially increased from 100 ° C. to 210 ° C. by 5 ° C. to form an image, and the low temperature offset phenomenon in which the toner image is not fixed on the recording paper, A non-offset region where no high temperature offset phenomenon in which the toner image is retransferred from the heating roller to the white background portion to be white background was examined to evaluate the offset resistance. The non-offset range is the minimum fixing temperature (° C) that is the minimum temperature of the superheated roller that does not cause the low temperature offset phenomenon, and the maximum fixing temperature (° C) that is the maximum temperature of the surface of the heating roller that does not cause the high temperature offset phenomenon. It is obtained from the temperature difference. In the evaluation of the non-offset region, the case where the non-offset region was 40 ° C. or higher was evaluated as good (◯), and the case where the non-offset region was less than 40 ° C. was evaluated as defective (×).

[Image density]
For the image formed when the surface temperature of the heating roller is 180 ° C., the reflection density meter (trade name: RD918, manufactured by Macbeth Co., Ltd.) is used to measure the optical reflection density of the solid image portion. did. A case where the image density was 1.40 or more was evaluated as good (◯), and a case where the image density was less than 1.40 was evaluated as defective (×).

  The results are shown in Table 1. In Table 1, the volume average particle diameter of the toner particles is expressed as “D50”. In Table 1, the melting point (° C) of the wax is paraffin: 72 ° C, carnauba: 85 ° C, polyethylene: 99 ° C, and fatty acid ester: 80 ° C.

  From Table 1, the toners of Examples 1 to 4 manufactured by the melt emulsification method using a polar wax and a non-polar wax as waxes have a very high wax residual ratio in the toner particles. It can be seen that the softening point of is shifted in the low temperature direction and a wide non-offset region of 40 ° C. or higher can be secured. The toners of Examples 1 to 4 have a small coefficient of variation of 33 or less, a narrow particle size distribution and a uniform particle size, and a volume average particle size of 7.0 μm or less. It can be seen that the toners of Examples 1 to 4 have uniform charging performance, excellent transferability, and can form an image having a high image density of 1.40 or more in terms of optical reflection density. On the other hand, the toners of Comparative Examples 1 to 4 manufactured by the melt emulsification method using only one kind of wax are examples in terms of the coefficient of variation and the reduction in toner diameter due to granulation in an aqueous medium. Although it is not inferior to the toners 1 to 4 and can form an image having a high image density, the toners of Comparative Examples 1 to 4 have a wax residual ratio after production of toner particles as compared with the toners of Examples 1 to 4 It can be seen that the toner of Examples 1 to 4 is inferior in terms of the low temperature offset and the non-offset area.

  As described above, according to the toner production method of the present invention, the wax dispersibility in the toner particles can be maintained, so that the residual wax ratio after the production of the toner particles can be increased, and a wide non-offset region is ensured. And a toner having a narrow particle size distribution.

Claims (9)

  A toner raw material is prepared by mixing a melt kneaded material of a toner raw material containing a binder resin, a colorant and two or more kinds of waxes having a melting point of 60 to 100 ° C. with an aqueous medium containing a dispersant and water under heating or heating and pressurization. A method for producing a toner, comprising a granulation step of preparing toner particles by granulating the melt-kneaded product.   2. The method for producing a toner according to claim 1, wherein the content of the two or more melting point waxes in the melt kneaded product of the toner raw material is 1 to 10% by weight of the total amount of the melt kneaded product.   3. The toner manufacturing method according to claim 1, wherein the binder resin is polyester.   The two or more kinds of waxes having a melting point of 60 to 100 ° C include a wax having a polar group having a melting point of 60 to 100 ° C and a wax having no polar group having a melting point of 60 to 100 ° C. 4. The method for producing a toner according to any one of 3 above.   The wax having a polar group having a melting point of 60 to 100 ° C. is a wax having a melting point of 60 to 100 ° C. and having one or more polar groups selected from an ester group, a hydroxyl group and a carboxyl group. Toner manufacturing method.   The wax having a polar group having a melting point of 60 to 100 ° C. is one or more selected from plant wax, synthetic fatty acid ester wax, wax obtained by air oxidation of petroleum wax, polyolefin polyol wax and paraffin polyol wax 6. The method for producing a toner according to claim 4, wherein the toner is a toner.   7. The wax according to claim 4, wherein the wax having a polar group having a melting point of 60 to 100 ° C. is one or more selected from plant waxes and synthetic fatty acid ester waxes. Toner manufacturing method.   The toner according to claim 4, wherein the wax having no polar group having a melting point of 60 to 100 ° C. is one or more selected from synthetic polyolefin wax and petroleum wax. Manufacturing method.   The method for producing a toner according to claim 1, wherein the dispersant is one or more selected from water-soluble polymer compounds.