JP2008089829A - Electrophotographic toner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic toner excellent in both of crushing performance and oilless performance. <P>SOLUTION: The electrophotographic toner is prepared by melt-kneading and crushing a raw material mixture which comprises a binder resin containing polyester resin, a colorant, a releasing agent containing polar wax and a crushing assistant containing cellulose or its derivative. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electrophotographic toner, and more particularly, to an electrophotographic toner having excellent pulverization properties and oilless properties.

  2. Description of the Related Art In recent years, image forming apparatuses such as printers used in offices have been desired to increase in speed with networking. In addition, a low-temperature fixing technique is desired in order to reduce the burden on the environment and to provide a quick start. As a characteristic required for toner for speeding up image forming apparatuses, it has a high durability capable of withstanding strong stress, and for low-temperature fixing, a characteristic required for toner is that it is melted at a low temperature. In order to improve the fixing property and the releasability, it is possible to include a release agent having a lower melting point than conventional ones.

  Here, in order to give the toner high toughness, when a polyester resin is used as the binder resin, when a polar wax such as carnauba wax is added to the polyester resin as a low melting point release agent, the wax is not dispersed. Since it was relatively good, there was a problem that the pulverization breaking point was reduced and the pulverization property was deteriorated.

  In order to solve this problem, measures such as lowering the supply amount at the time of pulverization are taken, but this leads to a decrease in productivity. Moreover, the to-be-crushed material which will be over-pulverized also increased, As a result, there existed a tendency for a fine powder to increase and for a yield to worsen.

  As a grinding aid for improving toner productivity, a toner containing an aliphatic hydrocarbon-aromatic hydrocarbon copolymer petroleum resin having 9 or more carbon atoms has been proposed (for example, see Patent Document 1). However, according to this toner, although the pulverization is improved, there is an adverse effect that the margin for durability and hot offset is lowered.

In addition, a toner to which a cellulose derivative is added is known (for example, see Patent Document 2). This is because a cellulose derivative is added to increase the cohesive force of the toner, and a low molecular weight component in the toner is added to a sleeve roller. This does not improve the pulverization property and oil-less property of the toner containing a predetermined binder resin and a release agent.
JP-A-11-72956 JP-A-62-94853

  The present invention has been made under the circumstances as described above, and an object thereof is to provide an electrophotographic toner excellent in both pulverization properties and oil-less properties.

  In order to solve the above problems, one embodiment of the present invention provides a raw material mixture containing a binder resin containing a polyester resin, a colorant, a release agent containing a polar wax, and a grinding aid containing cellulose or a derivative thereof. An electrophotographic toner characterized by being melt-kneaded and pulverized is provided.

  In such an electrophotographic toner, at least one selected from the group consisting of fatty acid cellulose, ethyl cellulose, and cellulose acetate can be used as the cellulose derivative.

  It is preferable that the compounding quantity of a cellulose or its derivative (s) is 5-10 mass%.

  According to the present invention, since a polar wax is used as a release agent and a grinding aid containing cellulose or a derivative thereof is used, an electrophotographic toner exhibiting excellent grinding properties and oil-less properties is provided.

  The best mode for carrying out the invention will be described below.

  An electrophotographic toner according to an embodiment of the present invention includes a polyester resin, a colorant, a polar wax, and cellulose or a derivative thereof.

  As the cellulose derivative, at least one selected from the group consisting of fatty acid cellulose, ethyl cellulose, and cellulose acetate can be used.

  Cellulose or a derivative thereof plays a role as a grinding aid in a grinding step in the toner production process described later. Cellulose or its derivatives are inferior in compatibility with the polyester resin as a binder resin, but do not affect the properties of the toner and increase the breaking point during pulverization. It becomes.

  The content of cellulose or a derivative thereof in the toner is preferably 5 to 10% by mass. If the content of cellulose or a derivative thereof in the toner is too large, fogging due to poor charging occurs frequently. If it is too small, the effect of addition is difficult to obtain.

  Examples of polar waxes include oxides of aliphatic hydrocarbon waxes such as oxidized polyethylene wax, and alcohols obtained by hydrolyzing these oxides, or block copolymers of these oxides; candelilla wax, carnauba wax, wood Plant waxes such as wax, rice wax and jojoba wax; animal waxes such as beeswax, lanolin and whale wax; mineral waxes such as ozokerite, ceresin and petrolactam; fatty acid esters such as montanic acid ester and caster wax Waxes obtained by deoxidizing a part or all of a fatty acid ester such as deoxidized carnauba wax.

  In addition, saturated linear fatty acids such as palmitic acid, stearic acid, montanic acid, or long-chain alkyl carboxylic acids having a long-chain alkyl group; unsaturated fatty acids such as brassic acid, eleostearic acid, and valinal acid; stearyl alcohol Saturated alcohols such as eicosyl alcohol, behenyl alcohol, carnauvir alcohol, seryl alcohol, melyl alcohol, or long chain alkyl alcohols having a long chain alkyl group; polyhydric alcohols such as sorbitol; linoleic acid amide, oleic acid Fatty acid amides such as amides and lauric acid amides; Saturated fatty acid bisamides such as methylene bisstearic acid amides, ethylene biscapric acid amides, ethylene bislauric acid amides and hexamethylene bisstearic acid amides; Unsaturated fatty acid amides such as N bis oleic acid amide, hexamethylene bis oleic acid amide, N, N′-dioleyl adipic acid amide, N, N′-dioleyl sebacic acid amide; Aromatic bisamides such as N'-distearylisophthalamide; fatty acid metal salts such as calcium stearate, calcium laurate, zinc stearate and magnesium stearate (generally referred to as metal soap); aliphatic hydrocarbon waxes Wax grafted with vinyl monomers such as styrene and acrylic acid; Partially esterified products of aliphatic and polyhydric alcohols such as behenic monoglyceride; Hydroxyl groups obtained by hydrogenating vegetable oils and fats Methyl ester Mention may also be made of the compound.

  The polar wax functions as a release agent and imparts excellent oil-less properties to the toner.

  The content of the polar wax in the toner is preferably 1 to 10% by mass. If the toner contains too much polar wax, the durability and storage stability will be adversely affected. If it is too little, oil-less properties will be reduced, and hot offset and paper wrapping around the fixing roller will likely occur. .

  The toner according to an embodiment of the present invention can be manufactured as follows using the components described above.

  First, a raw material mixture containing a polyester resin, a colorant, a polar wax, and cellulose or a derivative thereof is mixed with a mixer. As a mixing machine, arbitrary things, such as a Henschel mixer, a super mixer, a V-type blender, and a Nauta mixer, can be used.

  The raw material mixture is then fed to a kneader where it is melt kneaded. As the kneading machine, any type of extrusion kneading machine such as a twin-screw extrusion kneading machine and a single-screw extrusion kneading machine, an open roll type kneading machine such as a continuous two-roll mill, a continuous three-roll mill, and a batch roll mill can be used. Things can be used.

  The melt-kneaded product discharged from the kneader is usually cooled, pulverized, and classified to a predetermined particle size according to a method used for producing a toner to obtain a toner particle matrix. The cooling means, the pulverizing means, and the classification means are not particularly limited, and those usually used for toner production can be employed. For example, a cooling means by rolling or blowing an air flow can be used for cooling, and an airflow pulverizer such as a collision plate pulverizer can be used for pulverization, and various airflow classifiers can be used for classification. Can be used.

  Cellulose or a derivative thereof is contained in the melt-kneaded product, and this cellulose or a derivative thereof functions as a grinding aid during grinding. An electrophotographic toner can be obtained by adding an external additive such as silica to the toner particle matrix thus obtained, followed by mixing and stirring.

  Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples.

Example 1
A polyester resin (softening point 133 ° C., glass transition point 62 ° C.) 81% by mass as a binder resin, and C.I. 4 parts by weight of I Pigment Red 57: 1, 1% by mass of “E-84” (manufactured by Orient Chemical Co., Ltd .: salicylic acid metal complex) as a charge control agent, and “Carnauba wax No. 1 powder” as a release agent (Made by Kato Yoko Co., Ltd.) 4% by mass, after mixing 10% by mass of cellulose (manufactured by Chisso Co., Ltd .: celluflow C-25) as a grinding aid using a Henschel mixer (manufactured by Mitsui Mining Co., Ltd.) The mixture was melt-kneaded with a twin-screw extruder, pulverized with an impact plate pulverizer (IDS10), and classified with a gas stream classifier (DSX10) to obtain colored fine particles having a mass average particle diameter of about 6 μm.

  As an external additive, 1 part by mass of “R972” (manufactured by Nippon Aerosil Co., Ltd .: hydrophobic silica) was added to 100 parts by mass of the obtained colored fine particles and mixed with a Henschel mixer to obtain a toner.

Example 2
A toner was obtained in the same manner as in Example 1 except that the amount of cellulose (manufactured by Chisso Corporation: celluflow C-25) was changed to 5% by mass.

Comparative Example 1
A polyester resin (softening point 133 ° C., glass transition point 62 ° C.) 91% by mass as a binder resin, and C.I. I Pigment Red 57: 1: 4% by mass, “E-84” (manufactured by Orient Chemical Co., Ltd .: salicylic acid-based metal complex) as a charge control agent, 1% by mass, “Carnauba wax No. 1 powder” as a release agent 4% by mass (imported by Kato Yoko Co., Ltd.) was mixed using a Henschel mixer (Mitsui Mining Co., Ltd.), then melt-kneaded with a twin screw extruder, and pulverized and classified with a collision plate pulverizer. Thereafter, colored fine particles having a mass average particle diameter of about 6 μm were obtained.

  1 part by mass of “R972” (manufactured by Nippon Aerosil Co., Ltd .: hydrophobic silica) as an external additive was added to 100 parts by mass of the obtained colored fine particles and mixed with a Henschel mixer to obtain a toner.

Comparative Example 2
A toner was obtained in the same manner as in Example 1 except that polypropylene was used instead of carnauba wax as a release agent.

  The test methods and evaluation criteria for each performance of the toner are shown below.

1. Grindability When pulverizing a kneaded crushed product with a pulverizer (IDS10: air pressure 0.6 MPa) and a classifier (DSX10), the particle size of 6.0 μm, the number ratio of 4 μm or less is 25% or less, and the volume ratio of 16 μm or more The amount of feed of the coarsely crushed product when producing a toner base having a toner content of 1% or less is determined, and the following criteria are used to evaluate the feed amount. As the particle size distribution analyzer, Multisizer II (aperture size 100 μm) manufactured by Coulter Co., Ltd. was used.

Feed amount is 20kg / hr or more: ○
Feed amount less than 20 kg / hr: x
2. Oil-less property An image is printed by mounting it on “Page Presto N5” (manufactured by Casio Computer Co., Ltd.) from which the oil application unit has been removed, and evaluation is performed based on whether or not hot offset or paper wraps around the fixing roller.

No hot offset or paper wrapping around the fixing roller: ○
Hot offset or paper wrapping around the fixing roller occurs: ×
Table 1 below shows the results of measuring and evaluating the above characteristics of the toners according to Examples and Comparative Examples.

  From Table 1 above, the following can be understood. That is, when using a polar wax as a mold release agent and using a grinding aid made of cellulose or a derivative thereof (Examples 1 and 2), both the grindability and oilless property are good, In the case where a grinding aid made of cellulose or a derivative thereof is not used (Comparative Example 1), both the grindability and the oilless property are inferior, and in the case where polypropylene having a low polarity is used (Comparative Example 2) The oillessness is inferior.

  From the above results, it is clear that in order to obtain excellent pulverizability and oil-less properties, it is necessary to use a polar wax as a mold release agent and a pulverization aid made of cellulose or a derivative thereof.

Claims (3)

  An electron produced by melting and kneading a raw material mixture containing a binder resin containing a polyester resin, a colorant, a release agent containing a polar wax, and a grinding aid containing cellulose or a derivative thereof. Toner for photography.   2. The electrophotographic toner according to claim 1, wherein the cellulose derivative is at least one selected from the group consisting of fatty acid cellulose, ethyl cellulose, and cellulose acetate.   The toner for electrophotography according to claim 1 or 2, wherein the blending amount of the cellulose or a derivative thereof is 5 to 10% by mass.