JP4821637B2 - Toner for electrophotography - Google Patents

Description

  The present invention relates to an electrophotographic toner, and more particularly to an electrophotographic toner excellent in grindability, fogging, solid followability, and durability.

  In recent years, the performance required for electrophotographic toners has become increasingly sophisticated. The main requirements for toners are to reduce the particle size, reduce oil, fix at low temperature, increase transfer efficiency, and improve image quality. In order to satisfy these requirements, various substances are internally or externally added to the toner.

For example, in order to improve the transparency and fixability of the toner, it has been proposed to internally add silica or silicone oil (see, for example, Patent Documents 1 and 2).
In addition, in order to perform production with low energy so as to reduce the environmental load, in the case of pulverized toner, it is indispensable to use a material that is easily broken from the surface of the material, and it is possible to add a pulverization aid to the toner raw material. Needed. As a grinding aid for improving toner productivity, for example, it has been proposed to use a copolymer petroleum resin of an aliphatic hydrocarbon and an aromatic hydrocarbon having 9 or more carbon atoms (see, for example, Patent Document 3). However, when such a pulverization aid is used, although the pulverization is improved, there is a problem that durability and hot offset margin are lowered.

Therefore, there is a need for a grinding aid that not only improves the grindability but also does not affect the toner characteristics.
On the other hand, various methods have been proposed for externally adding additives to the pulverized and classified toner particles to improve toner characteristics (see, for example, Patent Documents 4 and 5).

  For example, in a non-magnetic one-component pulverized toner, it is an important factor that the toner is instantaneously and uniformly charged by frictional charging. Further, when the toner forms a thin toner layer on the developing roller due to the restriction of the doctor blade, it is necessary to instantly charge the toner. In this case, if the doctor blade is too pressed against the developing roller, the toner particles are fused to the doctor blade. On the contrary, if the pressing is too weak, the charging becomes non-uniform, and image unevenness due to thin layer formation failure (solid followability failure) and fogging due to charging failure occur.

  Therefore, it is required to improve such toner fusion to the doctor blade, poor solid followability and fog by using an external additive.

JP-A-2005-17660

JP 2004-198762 A

JP-A-11-72956

Japanese Patent No. 3198367

JP-A-5-224454

  The present invention is made under the circumstances as described above, and provides an electrophotographic toner excellent in pulverization, fog characteristics and solid followability, and electrophotographic toner excellent in durability, fog characteristics and solid followability. With the goal.

To solve the above problems, a first aspect of the present invention, a resin, a toner for electrophotography obtained by pulverizing the melt-kneaded product containing a coloring agent and grinding aid, as the grinding aid, plate There is provided an electrophotographic toner using a combined product of kaolinite and massive quartz and containing 0.1 to 15% by mass in the kneaded product.
A second aspect of the present invention, the toner body including a resin and a colorant, an electrophotographic toner obtained by adding an external additive, as the external additive, the plate-like kaolinite and bulk quartz An electrophotographic toner is provided, wherein a binder is used and the amount of the binder added is 0.1 to 5% by mass relative to the toner body.
In the first and second embodiments, the conjugate is silitin.

  According to the first aspect of the present invention, an electrophotographic toner excellent in grindability, fog characteristics and solid followability is provided. Moreover, according to the second aspect of the present invention, an electrophotographic toner excellent in durability, fog characteristics, and solid followability is provided.

Hereinafter, embodiments of the present invention will be described.
The electrophotographic toner according to the first embodiment of the present invention is characterized in that a combined product of plate-like kaolinite and massive quartz is used as a grinding aid. This combined product is fragile due to its specific structure, and has a high probability of becoming a break point of pulverization due to the force applied during pulverization of the toner kneaded product. Therefore, pulverization energy in toner production can be reduced.

A specific example of this conjugate is a natural mineral called so-called silitin. Siritin is a mineral produced in the Neuburg region of Germany, and has a structure in which about 20% plate-like kaolinite and 65% or more massive quartz are combined. Silytin is known to be added to plastics in order to improve wear resistance and light resistance, but no examples have been used as an additive for toners.

In addition, what surface-treated silitin with aminosilane, epoxy silane, mercapto silane, vinyl silane, tetrasulfane, hydrophobic silane etc. shows the same property as silitin, and exhibits the same effect.
Figure 1 shows the time of pulverization of the kneaded product of the toner materials, grinding aids consisting of binders, the manner in which example Sillitin is a breaking point. That is, when the lump 11 of the toner kneaded material containing the resin, the colorant, and silytin is subjected to the pulverization step, the silitin particles 12 become break points, and easily along the line 13 connecting the break points with low grinding energy. Crushing is performed.

It is necessary that the grinding aid comprising the combined product according to the present invention is contained in an amount of 0.1 to 15% by mass in the kneaded product. If it is less than 0.1% by mass, the effect as a grinding aid, that is, good pulverization property cannot be obtained, and if it exceeds 15% by mass, the pulverization property is good but fogging occurs. This is presumably because after the pulverization, a large amount of pulverized fine particles of the pulverization aid remains on the surface of the toner particles, which adversely affects the chargeability of the toner.

The electrophotographic toner according to the first embodiment of the present invention is manufactured as follows.
First, toner materials including a binder resin, a colorant, and a grinding aid are mixed using 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 from the kneader is usually cooled, pulverized, and classified to a predetermined particle size according to the method used for producing the 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 airflow can be used for cooling, an airflow pulverizer such as a collision plate pulverizer can be used for pulverization, and various airflow classifiers can be used for classification. it can.

An external additive such as titanium oxide particles hydrophobized with silicone oil is added to the toner particle matrix thus obtained, and mixed and stirred to obtain a toner.
The toner manufacturing method according to the first embodiment described above, the kneaded product after cooling, binding of the plate-like kaolinite and bulk quartz, for example because Sillitin contains, as shown in FIG. 1 The siritin particles 12 serve as break points, and pulverization can be easily performed with low pulverization energy along the line 13 connecting the break points.

Further, the obtained toner does not cause fogging or inferior in solid followability as in the case of using a conventional grinding aid.
Toner for electrophotography according to the second embodiment of the present invention, it was used was used as a grinding aid in the first embodiment described above, the binding of the plate-like kaolinite and bulk silica as an external additive It is characterized by. Since this combined substance is an inorganic substance, it has an abrasive action and can prevent the toner on the developing roller from fusing to the doctor blade. In addition, since this combined product has good chargeability, it is possible to promote the rise of charging of the toner.

As a specific example of this conjugate, there is the natural mineral called so-called siritin described above. Silytin is known to be added to plastics in order to improve wear resistance and light resistance, but no examples have been used as an additive for toners.
FIG. 2 is a diagram for explaining the action of the binder particles on the surface of the toner particles, for example, the silitin particles, during the development of the toner. That is, siltin particles 22 are attached to the surface of the toner particles 21 as an external additive. When the toner particles 21 are conveyed by the developing roller 23 and pass through the doctor blade 24 that regulates the toner layer thickness, The toner effect of the spacer 22 and the polishing effect due to the inorganic particles 22 are prevented from fusing the toner particles 21 to the surface of the doctor blade 24. Further, the obtained toner does not cause fogging or inferior in solid followability.

The external additive comprising the combined product according to the present invention needs to be contained in an amount of 0.1 to 5% by mass with respect to the toner particles. If it is less than 0.1% by mass, the effect of addition of external additives, that is, good durability, fog characteristics, and solid followability cannot be obtained, and if it exceeds 5% by mass, durability and solid followability are Although it is good, fogging occurs. This is presumably because a large amount of an external additive such as silytin remains on the surface of the toner particles, which adversely affects the chargeability of the toner.

The toner for electrophotography according to the second embodiment of the present invention is manufactured by the same manufacturing method as that used in the first embodiment except that the external additive contains silytin.
The binder resin that can be used for the toner according to the first and second embodiments of the present invention described above can be selected from a wide range including known ones. Specific examples include styrene resins such as polystyrene, styrene-acrylic acid ester copolymers, styrene-methacrylic acid copolymers, and styrene-butadiene copolymers, saturated polyester resins, unsaturated polyester resins, and epoxy resins. Phenolic resin, coumarone resin, xylene resin, vinyl chloride resin, polyolefin resin and the like can be exemplified, and two or more of these resins may be used in combination. Of these resins, polyester resins are preferred.

The toner according to the first and second embodiments of the present invention can contain a charge control agent and a release agent in addition to the binder resin, the colorant, and the grinding aid. As the charge control agent and the release agent, any of those usually used for electrophotographic toners can be used.
Test examples including examples and comparative examples of the present invention will be shown below, and the present invention will be described more specifically.

Test example 1
The following raw materials were mixed in a Henschel mixer (manufactured by Mitsui Mining Co., Ltd.) and melt-kneaded with a twin-screw extrusion kneader.
Cross-linked polyester resin (softening point 141 ° C., glass transition point 62 ° C.) 92% by mass
Colorant (C.I Pigment Red 57: 1) 3% by mass
Mold release agent (Sanyo Chemical Co., Ltd., Biscol 660P) 3% by mass
Charge control agent (E-84, manufactured by Orient Chemical Co., Ltd.) 1% by mass
Grinding aid (Siritin) 1% by mass
Next, the melt-kneaded product is cooled, pulverized to a mass average particle size of 8.8 μm with a collision plate type pulverizer (“IDS-10” manufactured by Nippon Pneumatic Industry Co., Ltd.), and further a classifier (Nippon Pneumatic Industry ( The product was classified by “DSX-10”), and colored fine particles having an average particle size of 9.0 μm were obtained.
Next, 100 parts by mass of the colored fine particles were mixed with 1 part by mass of hydrophobic silica (“R972” manufactured by Nippon Aerosil Co., Ltd.) using a Henschel mixer to obtain a magenta toner.

The magenta toner thus obtained is mounted on a developing device, and a non-magnetic one-component developing device “Casio Page Presto N-5” (manufactured by Casio Computer Co., Ltd .: color printer (A4 side) 29 sheets per minute) Thus, an image with a printing rate of 5% was continuously printed in a normal environment (25 ° C., 50% RH) and evaluated as follows.
Evaluation 1-Grindability Index When the kneaded and crushed material is pulverized and classified with a pulverizer (IDS10: air pressure 0.6 MPa) and a classifier (DSX10), the number ratio of an average particle diameter of 9.0 μm and a particle diameter of 3 μm or less is 4. % Or less, and the volume ratio of the particle size of 16 μm or more is judged by the feed amount of the coarsely pulverized product when producing a toner base having a volume ratio of 1% or less.

A multisizer II (aperture size 100 μm) manufactured by Coulter Co., Ltd. was used as a particle size distribution measuring instrument.
Practically, there is no problem if the feed amount is 20 kg / hr or more, so evaluation was made according to the following criteria.
(Evaluation criteria)
◯: Feed amount of 20 kg / hr or more X: Feed amount of less than 20 kg / hr Evaluation 2-fogging The fog when a blank paper was printed was visually evaluated.
(Evaluation criteria)
○: Fog is not recognized.
Δ: Slightly fogged.
X: There is clearly fog.
Evaluation 3-Solid followability The solid followability when a solid image was printed in the same manner as described above was visually evaluated. The process speed was 129.23 mm / sec and the fixing temperature was 150 ° C.
(Evaluation criteria)
○: Uniform solid image.
Δ: Slightly uneven conveyance.
X: Clearly uneven conveyance.

  The results of the above evaluation are shown in Table 1 below.

上記表１から、次のことが明らかである。即ち、シリチンを０．１〜１５質量％含有する原料混合物を用いて得た実施例１〜８のトナーは、粉砕性、カブリ、ベタ追従性のいずれも良好である。また、シリチンを表面処理したアクテジルを用いた実施例９〜１２も、同様に優れた結果が得られている。これは、粉砕助剤としてシリチン又はその表面処理物を添加することにより、粉砕の破断点を増加せしめ、粉砕性の良好なトナーを得ることができたためである。なお、シリチンはトナー特性に影響を与えないため、カブリ及びベタ追従性についても良好である。

From Table 1 above, the following is clear. That is, the toners of Examples 1 to 8 obtained by using the raw material mixture containing 0.1 to 15% by mass of silytin have good pulverization properties, fogging, and solid followability. Moreover, the excellent result was similarly obtained also in Examples 9-12 using the actilil which surface-treated silytin. This is because by adding silytin or a surface-treated product thereof as a grinding aid, the breaking point of grinding can be increased and a toner having good grinding properties can be obtained. Sicilin does not affect the toner characteristics, and therefore has good fog and solid follow-up properties.

  On the other hand, the toner of Comparative Example 1 obtained by using a raw material mixture containing only 0.05% by mass of silytin is inferior in grindability, and the raw material mixture containing as much as 16% by mass of siritin is used. The resulting toner of Comparative Example 2 was found to have fog. Further, the toners of Comparative Examples 3 to 4 obtained by using a raw material mixture containing silicon carbide and alumina instead of silitin have poor pulverization properties, fogging is observed, and solid followability is also poor depending on the type of alumina. There was a case.

Test example 2
The following raw materials were mixed in a Henschel mixer (manufactured by Mitsui Mining Co., Ltd.) and melt-kneaded with a twin-screw extrusion kneader.
Cross-linked polyester resin (softening point 141 ° C., glass transition point 62 ° C.) 93% by mass
Colorant (C.I Pigment Red 57: 1) 3% by mass
Mold release agent (Sanyo Chemical Co., Ltd., Biscol 660P) 3% by mass
Charge control agent (E-84, manufactured by Orient Chemical Co., Ltd.) 1% by mass
Next, the melt-kneaded product is cooled, pulverized to a mass average particle size of 8.8 μm with a collision plate type pulverizer (“IDS-10” manufactured by Nippon Pneumatic Industry Co., Ltd.), and further a classifier (Nippon Pneumatic Industry ( The product was classified by “DSX-10”), and colored fine particles having an average particle size of 9.0 μm were obtained.
Next, 1 part by mass of hydrophobic silica (“R972” manufactured by Nippon Aerosil Co., Ltd.) and silytin having an average particle diameter of 2 μm (Silicolloid: P87, commercially available from Tesco Co., Ltd.) were added to 100 parts by mass of the colored fine particles. Were mixed to obtain a magenta toner.

  The magenta toner thus obtained is mounted on a developing device, and a non-magnetic one-component developing device “Casio Page Presto N-5” (manufactured by Casio Computer Co., Ltd .: color printer (A4 side) 29 sheets per minute) Thus, an image with a printing rate of 5% was continuously printed in a normal environment (25 ° C., 50% RH) and evaluated as follows.

Evaluation 4-Durability Non-magnetic one-component developing device "Casio Page Presto N-5" (manufactured by Casio Computer Co., Ltd .: 29 color printers per minute) mounted with toner, normal environment (25 ° C, 50% RH) In Example 2), an image having a printing rate of 5% was continuously printed, and after 10,000 sheets were printed, the occurrence of white streaks due to the fusion of toner to the doctor blade when the solid image was printed was visually evaluated. The process speed was 34.1 mm / sec, and the fixing temperature was 150 ° C.
(Evaluation criteria)
○: No white streak occurred.
Δ: Several lines can be confirmed.
X: White streaks can be confirmed instantly.

In addition, about fog and solid followability, it evaluated by the evaluation criteria mentioned above.
The results of the above evaluation are shown in Table 2 below.

上記表２から、次のことが明らかである。即ち、シリチンを０．１〜５質量％外添して得た実施例１３〜１８のトナーは、耐久性、カブリ、ベタ追従性のいずれも良好であった。また、シリチンを表面処理したアクテジルを外添して得た実施例１９〜２２も、同様に優れた結果が得られた。これは、外添剤としてシリチン又はその表面処理物を用いることにより、トナー粒子がドクターブレードを通過する際に、シリチン粒子によるスペーサ効果と研磨効果により、トナー粒子がドクターブレードの表面に融着することが防止されたためである。

From Table 2 above, the following is clear. That is, the toners of Examples 13 to 18 obtained by externally adding 0.1 to 5% by mass of silytin were excellent in durability, fogging, and solid followability. In addition, excellent results were similarly obtained in Examples 19 to 22 obtained by externally adding actilil surface-treated with silytin. This is because the toner particles are fused to the surface of the doctor blade due to the spacer effect and polishing effect of the silitin particles when the toner particles pass through the doctor blade by using silytin or a surface-treated product thereof as an external additive. This is because it was prevented.

  On the other hand, the toner of Comparative Example 6 to which only 0.05% by mass of silytin is externally added is inferior in durability, and the toner of Comparative Example 7 obtained by externally adding as much as 5.5% by mass of silytin. The fog was observed. Further, the toner of Comparative Example 8 obtained by externally adding silicon carbide instead of silytin has poor solid followability, and the toners of Comparative Examples 9 and 10 obtained by externally adding alumina instead of silytin are fogged. Was recognized.

It is a figure explaining the effect | action of the siritin at the time of the grinding | pulverization of the kneaded material of a toner raw material. It is a figure for demonstrating the effect | action of the silytin at the time of toner development.

Explanation of symbols

11 ... lump of toner kneaded material, 12, 22 ... siritine particles, 13 ... line connecting break points,
21 ... toner particles, 23 ... developing roller, 24 ... doctor blade.

Claims (3)

An electrophotographic toner obtained by pulverizing a melt-kneaded material containing a resin, a colorant, and a grinding aid, wherein a combined product of plate-shaped kaolinite and massive quartz is used as the grinding aid, Is contained in an amount of 0.1 to 15% by mass. The toner body including a resin and a colorant, an electrophotographic toner obtained by adding an external additive, as the external additive, with the coupling product of the plate-like kaolinite and bulk quartz, the amount added The toner for electrophotography, which is 0.1 to 5% by mass with respect to the toner main body. The electrophotographic toner according to claim 1, wherein the combined product is silitin.

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