Toner and image forming apparatus

Abstract

To provide a toner that reduces passing from a blade and reduces filming without impairing low temperature fixability, and an image forming apparatus.SOLUTION: The present disclosure pertains to a toner comprising toner particles and an external adhesive attached to the surface of the toner particles. The toner particle includes crystalline polyester resin and wax. The external additive contains organic-inorganic composite fine particles and associated silica. The toner has a softening point of 110°C or less.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a toner and an image forming apparatus. [Background technology]

[0002] Toners have been disclosed in the past.

[0003] For example, Patent Document 1 discloses a method for producing associated silica in which two or more primary particles having an average particle size in the range of 5 to 500 nm are associated, characterized by reacting hydrophobic spherical silica fine particles having an average primary particle size of 0.01 to 200 nm in a humidified atmosphere at a temperature of 100 to 500°C, and discloses a toner in which compound silica is externally added to the surface of the toner particles.

[0004] Patent Document 2 discloses a toner having toner particles and organic-inorganic composite fine particles on the surfaces of the toner particles, the organic-inorganic composite fine particles having resin fine particles and inorganic fine particles embedded in the surfaces of the resin fine particles, with some of the inorganic fine particles exposed on the surfaces of the organic-inorganic composite fine particles, and the organic-inorganic composite fine particles satisfy a predetermined relationship, and the organic-inorganic composite particles are externally added to the surfaces of the toner particles. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-163622 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-130843 Summary of the Invention [Problem to be solved by the invention]

[0006] However, with the toners disclosed in the above documents (1) and (2), when external additives adhering to the surface of a photoreceptor are removed with a cleaning blade, the organic-inorganic composite particles may slip through the cleaning blade or filming may occur.

[0007] In view of the above problems, the present disclosure provides a toner and an image forming apparatus that can reduce slip-through from a cleaning blade and reduce filming without impairing low-temperature fixability. [Means for solving the problem]

[0008] One aspect of the present disclosure is a toner comprising toner particles and an external additive adhered to the surfaces of the toner particles, wherein the toner particles contain a crystalline polyester resin and a wax, the external additive contains organic-inorganic composite fine particles and associated silica, and the softening point of the toner is 110°C or less.

[0009] An image forming apparatus according to another aspect of the present disclosure includes the toner, an electrophotographic photosensitive member, and an image forming unit. [Effects of the Invention]

[0010] As described above, according to the present disclosure, it is possible to provide a toner and an image forming apparatus that can reduce slip-through from the cleaning blade and reduce filming without impairing low-temperature fixability. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic cross-sectional view of a toner according to the present disclosure. [Figure 2] FIG. 2 is an enlarged view of a portion II in FIG. [Figure 3] FIG. 3 is a diagram showing how an external additive adhering to the surface of a photoreceptor is removed by a cleaning blade. [Figure 4]FIG. 4 is a diagram showing how an external additive adhering to the surface of a photoreceptor is removed by a cleaning blade, and shows a case where the external additive is only organic-inorganic composite fine particles. [Figure 5] FIG. 5 is a diagram showing how an external additive adhering to the surface of a photoreceptor is removed by a cleaning blade, and shows a case where the external additive is only associated silica. [Figure 6] FIG. 6 is a diagram showing how an external additive adhering to the surface of a photoreceptor is removed by a cleaning blade, and shows a case where the external additive contains organic-inorganic composite fine particles and associated silica. [Figure 7] FIG. 7 is a schematic side view showing the configuration of the main part of the image forming apparatus according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0012] Preferred embodiments of the present disclosure will be described in detail below with reference to the drawings. Note that the embodiments described below do not unduly limit the content of the present disclosure described in the claims, and not all of the configurations described in the embodiments are necessarily essential as means for solving the problems of the present disclosure.

[0013] <Toner> Fig. 1 is a schematic cross-sectional view of a toner 1 according to the present disclosure. Fig. 2 is an enlarged view of a portion II in Fig. 1. As shown in Figs. 1 and 2, the toner 1 according to the present disclosure includes toner particles 10 and an external additive 20 adhered to the surfaces of the toner particles 10. The softening point of the toner 1 is 110°C or lower. First, a method for producing the toner 1 will be described.

[0014] The method for producing the toner 1 includes a toner particle production step for producing the toner particles 10 (toner cores).

[0015] In the toner particle production process, toner particles 10, which form the core of toner 1, are produced. As described above, toner particles 10 are particles containing a binder resin, a release agent, and a colorant, etc., and methods for producing toner particles 10 include, for example, dry methods such as a pulverization method, and wet methods such as a suspension polymerization method, an emulsion aggregation method, a dispersion polymerization method, a solution suspension method, and a melt emulsification method. A crystalline polyester resin and a wax are added to toner particles 10. Thus, toner particles 10 contain a crystalline polyester resin and a wax. A method for producing toner particles 10 by a pulverization method will be described below.

[0016] When the toner particles 10 are produced by a pulverization method, a toner composition containing a binder resin, a release agent, and optionally a colorant and a charge control agent is dry-mixed in a mixer, and then melt-kneaded in a kneader. The kneaded product obtained by the melt-kneading is cooled and solidified, and the solidified product is pulverized in a pulverizer. Thereafter, particle size adjustment is performed by classification or the like as necessary to obtain the toner particles 10.

[0017] Examples of mixers include Henschel-type mixers such as Henschel Mixer (trade name, manufactured by Mitsui Mining Co., Ltd.), Super Mixer (trade name, manufactured by Kawata Corporation), and Mechano Mill (trade name, manufactured by Okada Seiko Co., Ltd.), as well as Ang Mill (trade name, manufactured by Hosokawa Micron Corporation), Hybridization System (trade name, manufactured by Nara Machinery Works, Ltd.), and Cosmo System (trade name, manufactured by Kawasaki Heavy Industries, Ltd.).

[0018] Examples of kneaders that can be used include common kneaders such as twin-screw extruders, triple-roll mills, and lab blast mills. Specific examples include single- or twin-screw extruders such as TEM-100B (trade name, manufactured by Toshiba Machine Co., Ltd.), PCM-65 / 87, and PCM-30 (all trade names, manufactured by Ikegai Corporation), and open-roll kneaders such as Kneadex (trade name, manufactured by Mitsui Mining Co., Ltd.). Among these, open-roll kneaders are preferred.

[0019] Examples of crushers include jet crushers that use a supersonic jet stream to crush materials, and impact crushers that introduce solidified materials into the space formed between a rotor and a stator (liner) that rotate at high speed to crush the material.

[0020] As the classifier, for example, a swirling wind classifier (rotary wind classifier) ​​can be used.

[0021] The toner 1 of the present disclosure produced as described above is mixed with an external additive 20 that has functions such as improving powder fluidity, improving frictional charging properties, heat resistance, long-term storage properties, improving cleaning properties, and controlling the surface wear properties of the photoreceptor 40, and the external additive 20 is adhered to the surface of the toner particles 10.

[0022] As the external additive 20, for example, inorganic fine particles such as silica, titanium oxide, or alumina having an average particle diameter of 7 to 200 nm can be used, and inorganic fine particles that have been made hydrophobic by surface-treating the surface of these inorganic fine particles with a silane coupling agent, a titanium coupling agent, or silicone oil are preferred because they reduce the decrease in electrical resistance and charge amount under high humidity conditions.

[0023] The amount of external additive 20 added is preferably 0.2 to 3 parts by weight relative to the toner particles 10. If it is less than 0.2% by weight, it may be difficult to improve fluidity, and conversely, if it exceeds 3% by weight, fixability may decrease. More preferably, the amount of external additive 20 added is 1.0 to 1.2 parts by weight relative to the toner particles 10. If the amount of external additive 20 is less than 1.0 part by weight relative to the toner particles 10, the spacer effect may not be expected. On the other hand, if the amount of external additive 20 is more than 1.2 parts by weight relative to the toner particles 10, the external additive 20 detached from the toner particles 10 may cause filming.

[0024] The external additive 20 is generally added by mixing the toner particles 10 and the external additive 20 in an air mixer such as a Henschel mixer.

[0025] As described above, the toner 1 to which the external additive 20 has been externally added can be used as a one-component developer as is, or can be mixed with a carrier to use as a two-component developer. When used as a one-component developer, the toner is used alone without a carrier. When used as a one-component developer, the toner is transported by frictionally charging the toner with the developing sleeve using a cleaning blade 30a and a fur brush, causing the toner to adhere to the sleeve, and an image is formed.

[0026] The external additive 20 contains organic-inorganic composite fine particles 21 and associated silica 24 .

[0027] As shown in FIG. 2, the organic-inorganic composite particles 21 contain a polymer 22 and the above-described inorganic particles (inorganic material 23). The organic-inorganic composite particles 21 added as an external additive to the toner 1 according to the present disclosure have a structure in which inorganic particles (inorganic material 23) are embedded in the polymer 22 so that multiple protrusions derived from the inorganic particles are present on the surface of the resin particles. Examples of such organic-inorganic composite particles 21 include metal oxide-polymer composite particles in which a metal oxide is covalently bonded to a polymer, as described in JP 2013-92748 A, and specifically, ATLAS (product name) manufactured by Cabot Corporation. The organic-inorganic composite particles can be used after being partially or entirely modified by surface treatment. For example, organic-inorganic composite particles surface-treated with a hydrophobizing agent, as described in JP 2013-92748 A, are suitable as external additives.

[0028] As mentioned above, the inorganic material 23 may be metal oxide particles.

[0029] The metal oxide particles are covalently bonded to the polymer 22, the surface of the metal oxide is modified with a first hydrophobizing agent, the moisture content of the metal oxide-polymer composite particles is 0 wt % to about 10 wt % as measured after equilibration at 50% relative humidity and 25°C at about 1 atmosphere, and the density of the metal oxide-polymer composite particles is about 30% to about 90% of the density of the metal oxide as measured by helium pycnometry.

[0030] The moisture content of the metal oxide-polymer composite particles can be from 0 wt % to about 5 wt % as measured after equilibration at 50% relative humidity and 25°C at about 1 atmosphere. The toner composition can include from about 0.5 to about 7 wt % of the metal oxide-polymer composite particles. The metal oxide-polymer composite particles have a diameter of from about 50 nm to about 500 nm. At least a portion of the metal oxide particles can be exposed at the surface of the metal oxide-polymer composite particles.

[0031] The polymer 22 can include a polymer 22 or copolymer of a first hydrophobizing agent. The metal oxide particles can include precipitated or colloidal metal oxide particles. The surface of the metal oxide particles can be modified with a second hydrophobizing agent. The second hydrophobizing agent can be selected from silazane compounds, siloxane compounds, silane compounds, and silicone fluids having a number average molecular weight of at most 10,000. The first hydrophobizing agent has the formula Si[H3-x(OR1)x]R2Q, where x is 1, 2, or 3, R1 is methyl or ethyl, R2 is an alkyl linker having the general formula CH2n (n is 1-10), and Q is a substituted or unsubstituted vinyl, acrylate, or methacrylate group.

[0032] The metal oxide-polymer composite particles can be treated with a third hydrophobizing agent. The third hydrophobizing agent can be an alkylhalosilane or a silicone fluid having a number average molecular weight greater than 10,000. The polymer 22 can be selected from acrylates and methacrylates, olefins, vinyl esters and acrylonitriles, and copolymers and mixtures thereof. The metal oxide-polymer composite particles can have an aspect ratio of about 0.8 to about 1.2. About 5% to about 95% of the length of the metal oxide particles can be exposed at the surface of the metal oxide-polymer composite particles.

[0033] As used herein, associated silica 24 does not refer to secondary particles (aggregates) formed by loosely adhering primary particles, but rather to secondary particles formed by firmly adhering primary particles that are difficult to disintegrate. This refers to particles formed by the association of two or more primary particles into chains, fibers, or other irregular shapes. Examples of such shapes include associations of two primary particles, associations of three or more primary particles into chains, associations of three primary particles at three points, associations of four primary particles in a planar or tetrapod-like configuration, associations of five or more primary particles, and associations of these silica groups bonded together. Here, "primary particles" refers to the smallest unit of particles forming a powder. Such particles (associated silica 24) have advantages over typical particles formed by the aggregation of primary particles into spherical shapes or clumps in terms of the shape and area of ​​adhesion to toner surfaces, etc. Note that the term "primary particles" refers to the smallest unit of particles forming a powder.

[0034] The forms of the silica particles include those in which two primary particles are associated, those in which three or more particles are associated in a chain, those in which three particles are associated at three points, those in which four particles are associated in a planar or tetrapod-like configuration, those in which five or more particles are associated, and those in which these associated silica groups are bonded together.

[0035] Here, the term "primary particle" refers to a particle that is the smallest unit of particles forming a powder. Since association-type silica particles have a larger contact (adhesion) area with the surface of the toner base particle than silica particles with a normal shape, they are less likely to detach from the toner surface. Furthermore, since association-type silica particles have an irregular shape, they are less likely to aggregate, so they can suppress the occurrence of filming while ensuring a sufficient spacer effect.

[0036] The average particle size of the primary particles of the associated silica 24 used in the present disclosure is preferably 10 nm or more and 200 nm or less. When the average particle size of the primary particles of the associated silica is within the range of 10 nm or more and 200 nm or less, the functions required of the external additive 20, that is, preventing aggregation of the toner 1 particles and improving the transferability of the toner 1, can be achieved.

[0037] The shape of the primary particles constituting the association type silica may be any of spherical, ovoid, cubic, and rod-like, but spherical is preferred for use as an external additive. The particle diameters of the primary particles may be different from one another.

[0038] Associated silica can be produced by the method described in JP 2012-025596 A, or a commercially available product such as that used in the examples can also be used.

[0039] The softening point of the toner 1 according to the present disclosure is 110° C. or lower. The softening point is preferably 90° C. or higher and 110° C. or lower, more preferably 100° C. or higher and 110° C. or lower, and even more preferably 105° C. or higher and 110° C. or lower. If the softening point is lower than the lower limit, the external additive 20 tends to be embedded in the surface of the toner particles 10, deteriorating dispersibility and the dispersibility of the silica particles, which may increase the amount of film loss on the photosensitive drum and deteriorate environmental charging performance.

[0040] Next, the mechanisms by which slip-through and filming occur will be described. Fig. 3 is a diagram showing how external additive 20 adhering to the surface of photoreceptor 40 is cleaned by cleaning blade 30a. Below, we will explain the cases where external additive 20 consists of only organic-inorganic composite fine particles 21, where external additive 20 consists of only associated silica 24, and where external additive 20 contains both organic-inorganic composite fine particles 21 and associated silica 24.

[0041] Fig. 4 is a diagram showing how external additive 20 adhering to the surface of photoreceptor 40 is cleaned by cleaning blade 30a, and shows a case where external additive 20 consists only of organic-inorganic composite fine particles 21. Fig. 5 is a diagram showing how external additive 20 adhering to the surface of photoreceptor 40 is cleaned by cleaning blade 30a, and shows a case where external additive 20 consists only of associated silica 24. Fig. 6 is a diagram showing how external additive 20 adhering to the surface of photoreceptor 40 is cleaned by cleaning blade 30a, and shows a case where external additive 20 contains organic-inorganic composite fine particles 21 and associated silica 24.

[0042] When the external additive 20 is only organic-inorganic composite fine particles 21, as shown in Figure 4, the organic-inorganic composite fine particles 21 have inorganic material 23 on the surface of polymer 22 and have a structure with multiple convex portions, so that the external additive 20 slips through the cleaning blade 30a, a phenomenon known as slip-through.

[0043] On the other hand, when the external additive 20 is only associated silica 24, as shown in FIG. 5, the particles of associated silica 24 tend to aggregate and have an irregular shape, so that the external additive 20 tends to remain on the cleaning blade 30a, condensing and causing so-called filming.

[0044] Therefore, when the external additive 20 contains organic-inorganic composite fine particles 21 and associated silica 24, as in the toner 1 according to the present disclosure, as shown in FIG. 6, the toner 1 according to the present disclosure contains associated silica 24, which tends to remain to some extent in the external additive, and thereby can block the organic-inorganic composite fine particles 21, thereby reducing slip-through and filming.

[0045] However, if the amount of associated silica 24 in the toner 1 is too small, the organic-inorganic composite fine particles 21 cannot be blocked, and they may easily slip through. Conversely, if the amount of associated silica 24 in the toner 1 is too large, aggregation of the associated silica 24 may occur, and filming may easily occur.

[0046] Therefore, it is preferable that the organic-inorganic composite fine particles 21 are contained in an amount of 75 to 90 wt % relative to the external additive 20. If the organic-inorganic composite fine particles 21 are contained in an amount of less than 75 wt % relative to the external additive 20, filming may be more likely to occur as described above. On the other hand, if the organic-inorganic composite fine particles 21 are contained in an amount of more than 90 wt % relative to the external additive 20, the external additive 20 may be more likely to slip through.

[0047] Furthermore, the particle diameter of the organic-inorganic composite fine particles 21 is preferably 70 to 200 nm. If the particle diameter of the organic-inorganic composite fine particles 21 is less than 70 nm, the spacer effect is reduced and the external additive 20 may slip through the cleaning blade 30a more easily. On the other hand, if the particle diameter of the organic-inorganic composite fine particles 21 is greater than 200 nm, the external additive 20 may be more easily detached from the toner 1. Therefore, by setting the particle diameter within the above range, the organic-inorganic composite fine particles 21 are external additives 20 with a large particle diameter, and therefore can impart a spacer effect to the toner 1. Furthermore, since the organic-inorganic composite fine particles 21 have a shape with multiple convex portions, they adhere firmly to the surface of the toner particles 10 and are less likely to be unevenly distributed in the concave portions of the toner particles 10.

[0048] Furthermore, the degree of association of the associated silica 24 is preferably 2.0 to 3.0. This can further reduce filming. If the degree of association of the associated silica 24 is less than 2.0, the shape approaches spherical silica, which tends to concentrate in recesses on the surface of the toner particles 10, potentially weakening the spacer effect. On the other hand, if the degree of association of the associated silica 24 is greater than 3.0, it tends to form aggregates on the cleaning blade 30a, potentially worsening filming. Therefore, by setting the degree of association within the above range, the associated silica 24 has an irregular shape and therefore tends to adhere firmly to the surface of the toner particles 10. However, a certain degree of association is necessary to achieve the effect of the irregular shape, and if the degree of association is too high, it becomes difficult for the silica to be detached from the cleaning blade 30a.

[0049] The particle size of the associated silica 24 is preferably 100 to 300 nm. If the particle size of the associated silica 24 is less than 100 nm, the spacer effect may not be expected. On the other hand, if the particle size of the associated silica 24 is greater than 300 nm, aggregates may be easily formed on the cleaning blade 30a, which may worsen filming. Therefore, by setting the particle size within the above range, it is possible to prevent aggregate formation on the cleaning blade 30a and improve filming.

[0050] Furthermore, the particle diameter of the organic-inorganic composite fine particles 21 is preferably smaller than the particle diameter of the associated silica 24. In this way, it is possible to further prevent the organic-inorganic composite fine particles 21 from slipping through.

[0051] Furthermore, it is preferable that the bulk density of the toner 1 is 0.38 or more. This ensures good fluidity of the toner 1, allowing the toner 1 to be transferred in accordance with the irregularities on the paper surface, resulting in high image quality.

[0052] Furthermore, the adhesion strength of the external additive 20 to the toner particles 10 is preferably 70% or less. If the adhesion strength of the external additive 20 to the toner particles 10 is greater than 70%, the spacer effect may be reduced, and the external additive 20 may be embedded in the surface of the toner particles 10, which may deteriorate the fluidity of the toner 1.

[0053] As described above, with the toner 1 according to the present disclosure, by externally adding both the organic-inorganic composite fine particles 21 and the associated silica 24, the problem can be solved by preventing the organic-inorganic composite fine particles 21 from slipping through the cleaning blade 30a without impairing the low-temperature fixability. Furthermore, since the fluidity of the toner 1 can be ensured, it can be transferred in accordance with the unevenness of the paper surface, thereby achieving high image quality.

[0054] <Image forming device> 7 is a schematic side view showing the configuration of the main parts of an image forming apparatus 100 according to the present disclosure. The image forming apparatus 100 according to the present disclosure includes the above-described toner 1, a photoreceptor 40 (hereinafter also referred to as an electrophotographic photoreceptor 40), and an image forming unit 50. The image forming apparatus 100 may be, for example, a laser printer.

[0055] The toner 1 used is the one described above.

[0056] The image forming section 50 forms an image by charging the electrophotographic photosensitive member 40 with the charging roller 32, exposing, transferring and fixing the image. The image forming section 50 will be described below.

[0057] As shown in Figure 7, the image forming unit 50 includes a housing 38, a charging unit 32 that charges the electrophotographic photosensitive member 40, an exposure unit 31 that exposes the charged photosensitive member 40 to light to form an electrostatic latent image, a development unit 33 that develops the electrostatic latent image formed by exposure to form a toner image (makes it visible), a transfer unit 34 that transfers the toner image formed by development onto a recording medium 45, a fixing unit 35 that fixes the transferred toner image on the recording medium 45 to form an image, a cleaning unit 30 that removes and collects external additives 20 remaining on the photosensitive member 40, and a discharging unit (not shown) that discharging surface charges remaining on the photosensitive member 40.

[0058] The electrophotographic photosensitive member 40 is rotatably supported by the main body of the image forming apparatus 100, and is driven to rotate around a rotation axis 44 in the direction of arrow 41 by a drive unit (not shown). The drive unit includes, for example, an electric motor and a reduction gear, and transmits its driving force to a conductive support constituting the core of the electrophotographic photosensitive member 40, thereby driving and rotating the electrophotographic photosensitive member 40 at a predetermined peripheral speed. A charging unit (charger) 32, an exposure unit 31, a developing unit (developer) 33, a transfer unit (transfer charger) 34, and a cleaning unit (cleaner) 30 are provided in this order along the outer circumferential surface of the electrophotographic photosensitive member 40, from the upstream side to the downstream side in the direction of rotation of the electrophotographic photosensitive member 40 indicated by arrow 41.

[0059] The charging unit 32 is a roller charger that uniformly charges the outer peripheral surface of the electrophotographic photosensitive member 40 to a predetermined potential. The exposure unit 31 has a semiconductor laser as a light source, and irradiates the surface of the electrophotographic photosensitive member 40 between the charger 32 and the developing unit 33 with a laser beam light output from the light source, thereby exposing the charged outer peripheral surface of the electrophotographic photosensitive member 40 in accordance with image information. The light is repeatedly scanned in the main scanning direction, that is, the direction along which the rotation axis 44 of the electrophotographic photosensitive member 40 extends, and these light beams are focused to sequentially form electrostatic latent images on the surface of the electrophotographic photosensitive member 40. In other words, the amount of charge on the electrophotographic photosensitive member 40 that has been uniformly charged by the charger 32 differs depending on whether or not it is irradiated with the laser beam, thereby forming an electrostatic latent image.

[0060] The developing unit 33 is a developing device that develops an electrostatic latent image formed on the surface of the electrophotographic photosensitive member 40 by exposure with a developer (toner 1), and is provided facing the electrophotographic photosensitive member 40 and includes a developing roller 33a that supplies toner 1 to the outer peripheral surface of the electrophotographic photosensitive member 40, and a casing 33b that supports the developing roller 33a rotatably around a rotation axis parallel to the rotation axis 44 of the electrophotographic photosensitive member 40 and contains a developer including toner 1 in its internal space.

[0061] The transfer unit 34 is a transfer charger that transfers the toner image, which is a visible image formed on the outer peripheral surface of the electrophotographic photosensitive member 40 by development, onto a transfer paper, which is a recording medium 45, that is supplied between the electrophotographic photosensitive member 40 and the transfer charger 34 from the direction of the arrow 42 by a transport unit (not shown). The transfer unit 34 is, for example, a contact-type transfer charger that includes the charging unit 32 and transfers the toner image onto the transfer paper by applying a charge of the opposite polarity to that of the toner 1 to the transfer paper.

[0062] As described above, the cleaning unit 30 removes the toner 1 and the external additives 20 remaining on the outer peripheral surface of the electrophotographic photosensitive member 40. The cleaning unit 30 removes the toner 1 and the external additives 20 after the transfer operation by the transfer charger 34. The cleaning unit 30 is a cleaner and includes a cleaning blade 30a that separates the toner 1 and the external additives 20 remaining on the outer peripheral surface of the electrophotographic photosensitive member 40, and a recovery casing 30b that contains the toner separated by the cleaning blade 30a. The cleaning unit 30 is also provided together with a static elimination lamp (not shown).

[0063] In the cleaning unit 30, the toner according to the present disclosure reduces slip-through from the cleaning blade 30a and reduces filming.

[0064] The image forming apparatus 100 is also provided with a fixing unit 35 that fixes the transferred image, located downstream of the transport path of the transfer paper 45 that has passed between the electrophotographic photosensitive member 40 and the transfer charger 34. The fixing unit 35 includes a heating roller 35a having a heating portion (not shown), and a pressure roller 35b that is disposed opposite the heating roller 35a and is pressed against the heating roller 35a to form a contact portion. Reference numeral 37 denotes a separating unit 37 that separates the transfer paper 45 from the electrophotographic photosensitive member 40, and reference numeral 38 denotes a casing that houses the above-mentioned components of the image forming apparatus 100.

[0065] The image forming operation by this image forming apparatus 100 is performed as follows: First, when the electrophotographic photosensitive member 40 is rotationally driven in the direction of arrow 41 by the drive unit, the surface of the electrophotographic photosensitive member 40 is uniformly charged to a predetermined positive potential by the charger 32 provided upstream of the image formation point of light by the exposure unit 31 in the rotation direction of the electrophotographic photosensitive member 40.

[0066] Next, light corresponding to image information is irradiated from the exposure unit 31 onto the surface of the electrophotographic photosensitive member 40. This exposure removes surface charge from the portions of the electrophotographic photosensitive member 40 irradiated with light, creating a difference in surface potential between the portions irradiated with light and the portions not irradiated with light, thereby forming an electrostatic latent image. Toner 1 is supplied from a developing unit 33, which is provided downstream in the rotation direction of the electrophotographic photosensitive member 40 from the image-forming point of the light by the exposure unit 31, to the surface of the electrophotographic photosensitive member 40 on which the electrostatic latent image has been formed, thereby developing the electrostatic latent image into a toner image.

[0067] In synchronization with the exposure of the electrophotographic photosensitive member 40, transfer paper 45 is supplied between the electrophotographic photosensitive member 40 and transfer charger 34. The transfer charger 34 imparts a charge of opposite polarity to that of the toner 1 to the supplied transfer paper 45, and the toner image formed on the surface of the electrophotographic photosensitive member 40 is transferred onto the transfer paper. The transfer paper 45 with the transferred toner image is transported to the fixing device 35 by the transport unit, and is heated and pressed as it passes through the contact area between the heating roller 35a and the pressure roller 35b of the fixing device 35, and the toner image is fixed to the transfer paper 45 to form a solid image. The transfer paper 45 with the image formed in this way is discharged to the outside of the image forming apparatus 100 by the transport unit.

[0068] On the other hand, the toner 1 remaining on the surface of the electrophotographic photosensitive member 40 after the transfer of the toner image by the transfer charger 34 is peeled off from the surface of the electrophotographic photosensitive member 40 and collected by the cleaning unit 30. The charge on the surface of the electrophotographic photosensitive member 40 from which the toner 1 has been removed in this way is removed by light from the discharging lamp, and the electrostatic latent image on the surface of the electrophotographic photosensitive member 40 disappears. Thereafter, the electrophotographic photosensitive member 40 is further rotated, and a series of operations starting from charging are repeated again to form images continuously.

[0069] The process cartridge is characterized by comprising the electrophotographic photosensitive member 40 of the present disclosure, and at least one selected from a charging unit 32 that charges the electrophotographic photosensitive member 40, a developing unit 33 that develops an electrostatic latent image formed by exposure to light to form a toner image, and a cleaning unit 30 that removes toner 1 remaining on the electrophotographic photosensitive member 40.

[0070] For example, a process cartridge is configured by integrating the electrophotographic photosensitive member 40 of the present disclosure, a charging device, a developing device, and a cleaning device into a support member. When such a process cartridge is incorporated into the image forming apparatus 100, each of the components of the process cartridge is provided in the image forming apparatus 100. Because the process cartridge is detachable from the image forming apparatus 100, it can be easily replaced when worn out.

[0071] As described above, image forming apparatus 100 according to the present disclosure can reduce toner passing through the blade and reduce filming without impairing low-temperature fixability. [Example]

[0072] The toner according to the present disclosure will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the examples described here.

[0073] Example 1 Toner particles (toner cores) were obtained based on the above-described particle production process.

[0074] Next, 1.0 part by mass of silica particles "R976S" (manufactured by Nippon Aerosil Co., Ltd., particle size: 7 nm) was added to 100 parts by mass of the obtained toner particles, and the following materials were pre-mixed for 5 minutes (mixing process) using an air flow mixer (Henschel mixer, manufactured by Mitsui Mining Co., Ltd. (now Nippon Coke and Engineering Co., Ltd.), model: FM20C) with the tip speed of the stirring blade set to 40 m / sec. Colorant: CI Pigment Blue 15:3 (DIC Corporation) 7% by weight Release agent: Monoester wax (NOF Corporation, product name: WEP-3) 5% by mass Charge control agent: salicylic acid compound (Orient Chemical Industry Co., Ltd., product name: Bontron E-84) 1% by mass

[0075] Next, the mixture was melt-kneaded using an open-roll type continuous kneader (manufactured by Mitsui Mining Co., Ltd. (now Nippon Coke and Engineering Co., Ltd.), model: MOS320-1800) to obtain a melt-kneaded product (kneading step). The open roll conditions were as follows: the heating roll had a supply-side temperature of 130°C, a discharge-side temperature of 100°C, and a cooling roll had a supply-side temperature of 40°C, and a discharge-side temperature of 25°C. The heating roll and cooling roll had a diameter of 320 mm and an effective length of 1550 mm, and the gap between the rolls on both the supply side and the discharge side was 0.3 mm. The heating roll rotation speed was 75 rpm, the cooling roll rotation speed was 65 rpm, and the toner raw material supply rate was 5.0 kg / h.

[0076] The resulting molten kneaded product was cooled on a cooling belt and then coarsely pulverized using a speed mill equipped with a φ2 mm screen to obtain a coarsely pulverized product, which was then finely pulverized using a jet pulverizer (manufactured by Nippon Pneumatic Mfg. Co., Ltd., model: IDS-2) to obtain a finely pulverized product (fine pulverization step).

[0077] Next, the obtained finely pulverized product was classified using an elbow jet classifier (manufactured by Nittetsu Mining Co., Ltd., model: EJ-LABO) to obtain toner particles (classification step).

[0078] The external addition conditions are as follows:

[0079] To 100 parts by mass of the obtained toner particles, 1.0 part by mass of silica particles "R976S" (manufactured by Nippon Aerosil Co., Ltd., particle size: 7 nm) was added, and the mixture was stirred for 4 minutes using an air mixer (Henschel mixer, manufactured by Mitsui Mining Co., Ltd. (now Nippon Coke and Engineering Co., Ltd.), model: FM20C) with the tip speed of the stirring blade set to 40 m / sec. Then, external additives A and B were prepared. External additive A is organic-inorganic composite fine particles, and external additive B is associated silica.

[0080] Then, 0.9 parts by mass of external additive A and 0.2 parts by mass of external additive B were added to the toner particles, and the tip speed of the air flow mixer was set to 40 m / s and the mixture was stirred for 2 minutes to adhere the external additives, thereby obtaining the toner of Example 1.

[0081] Details of the toner obtained in Example 1 are shown in Table 1.

[0082] Example 2 The particle size of the external additive A was changed to 150 nm, and a toner according to Example 2 was obtained. The other conditions were the same as those of Example 1.

[0083] Example 3 The particle size of the external additive A was changed to 300 nm, and a toner according to Example 3 was obtained. The other conditions were the same as those of Example 1.

[0084] Example 4 The particle size of the external additive A was changed to 50 nm, and a toner according to Example 4 was obtained. The other conditions were the same as those of Example 1.

[0085] Example 5 The degree of association of the external additive B was adjusted to 2.8, and a toner according to Example 5 was obtained. The other conditions were the same as those of Example 1.

[0086] Example 6 The degree of association of the external additive B was adjusted to 5, and a toner according to Example 6 was obtained. The other conditions were the same as those of Example 1.

[0087] Example 7 The particle size of the external additive B was changed to 220 nm, and a toner according to Example 7 was obtained. The other conditions were the same as those of Example 1.

[0088] Example 8 The particle size of the external additive B was changed to 330 nm, and a toner according to Example 8 was obtained. The other conditions were the same as those of Example 1.

[0089] Example 9 The particle size of the external additive B was changed to 70 nm, and a toner according to Example 9 was obtained. The other conditions were the same as those of Example 1.

[0090] Example 10 The amount of external additive A was changed to 0.3 parts by weight, and the amount of external additive B was changed to 0.1 parts by weight, to obtain a toner according to Example 10. The other conditions were the same as in Example 1.

[0091] Example 11 The amount of external additive A was changed to 1.8 parts by weight, and the amount of external additive B was changed to 0.4 parts by weight, to obtain a toner according to Example 11. The other conditions were the same as in Example 1.

[0092] Example 12 The amount of external additive A was changed to 0.6 parts by weight, and the amount of external additive B was changed to 0.5 parts by weight, so that the weight ratio of external additive A to external additive B was 6:5, and a toner according to Example 12 was obtained. The other conditions were the same as in Example 1.

[0093] Example 13 The amount of external additive A was changed to 1.0 part by weight, and the amount of external additive B was changed to 0.1 part by weight, so that the weight ratio of external additive A to external additive B was 10:1, thereby obtaining a toner according to Example 13. The other conditions were the same as in Example 1.

[0094] Example 14 The bulk density of the toner was adjusted to 0.36, to obtain a toner according to Example 14. The other conditions were the same as in Example 1. At this time, the adhesion strength of the external additive to the toner particles was 75%.

[0095] (Comparative Example 1) In Comparative Example 1, the external additive A of the organic-inorganic composite fine particles was not added to the toner particles, and only the external additive B was added to obtain the toner according to Comparative Example 1. The stirring after adding the external additive was carried out for 4 minutes. The other conditions were the same as those in Example 1.

[0096] (Comparative Example 2) In Comparative Example 2, the external additive B of the organic-inorganic composite fine particles was not added to the toner particles, and only the external additive A was added to obtain a toner according to Comparative Example 2. The other conditions were the same as in Example 1.

[0097] (Comparative Example 3) In Comparative Example 3, external additive B of organic-inorganic composite fine particles was not added to the toner particles, and only external additive A was added in an amount of 0.9 parts by weight relative to the toner particles. In addition, 110 nm spherical silica was added in an amount of 0.2 parts by weight relative to the toner particles. In this way, a toner according to Comparative Example 3 was obtained. The other conditions were the same as in Example 1. The spherical silica was added to obtain a spacer effect.

[0098] Comparative Example 4 In Comparative Example 4, external additive A of organic-inorganic composite fine particles was not added to the toner particles, and only external additive B was added in an amount of 0.2 parts by weight relative to the toner particles. In addition, 110 nm spherical silica was added in an amount of 0.9 parts by weight relative to the toner particles. In this way, a toner according to Comparative Example 4 was obtained. Other conditions were the same as in Example 1.

[0099] (Comparative Example 5) In Comparative Example 5, the blending ratio in the above mixing step was changed to 87% by mass of amorphous polyester resin and 0% by mass of crystalline polyester resin, thereby obtaining toner particles with a different softening point from the above. The other conditions were the same as in Example 1, and a toner according to Comparative Example 5 was obtained.

[0100] The evaluation of low temperature offset is as follows.

[0101] The prepared developer and toner were loaded into a commercially available copier (product name: MX-5111FN, manufactured by Sharp Corporation), and an A4 test document having a rectangular solid image measuring 20 mm in length and 50 mm in width was copied onto a recording medium (product name: PPC paper SF-4AM3, manufactured by Sharp Corporation) to check whether low-temperature offset occurred. At this time, the amount of toner adhered to the solid image area was 0.5 mg / cm. 2 The temperature of the fixing roller was set to 135°C.

[0102] Low-temperature offset refers to the phenomenon in which toner does not fuse to the recording paper during fixing, but remains attached to the fixing roller, and then re-adheses to the recording paper after the fixing roller has made one revolution. Filming resistance was also evaluated according to the following criteria.

[0103] Good: No toner re-adhesion to the recording paper was observed. Bad: Toner re-adhesion to the recording paper is clearly visible.

[0104] The filming evaluation is as follows:

[0105] The prepared developer and toner were loaded into the developing device and toner cartridge of a color multifunction printer (Model MX-5100FN, manufactured by Sharp Corporation), respectively. Next, a continuous print test of 50,000 sheets of A4 paper was carried out in an environment with a temperature of 25°C and humidity of 5%, so that a 10 mm square solid image (ID=1.45-1.50) was formed at three positions in the center and both ends in the axial direction of the developing roller.

[0106] Thereafter, a solid image (ID: 1.6 to 1.8) and a halftone (HT) image (ID: 0.5 to 0.7) were printed on A3 paper, and the resulting images were visually observed and evaluated for filming resistance according to the following criteria.

[0107] Excellent: There are no image defects (white streaks, etc.) in both solid and HT images, and no streaks are observed on the photoconductor surface. Good: There are no image defects (white streaks, etc.) in both solid and HT images, but some streaks are observed on the photoreceptor surface. Available: There are no image defects (white streaks, etc.) in the solid image, but slight image defects (white streaks, etc.) can be seen in the HT image, and streaks are partially observed on the photoconductor surface. Bad (unacceptable): Defects (white streaks, etc.) are visible on both the solid image and the HT image, and streaks are observed all over the surface of the photoconductor.

[0108] The softening point of the toner particles is measured as follows.

[0109] Using a flow property evaluation device (product name: Flow Tester CFT-100C, manufactured by Shimadzu Corporation), 1 g of sample was heated at a temperature increase rate of 6°C per minute, and a load of 20 kgf / cm2 (9.8 x 105 Pa) was applied, and the temperature at which the sample began to flow out of a die (nozzle diameter 1 mm, length 1 mm) was taken as the softening temperature. The softening points of the toners according to Examples 1 to 14 and Comparative Examples 1 to 4 were 110°C, and the softening point of the toner of Comparative Example 5 was 125°C.

[0110] The transferability was evaluated as follows.

[0111] Using a test copying machine modified from a digital copying machine (manufactured by Sharp Corporation, model: MX-5100FN), the secondary transfer current was changed from -45 μA to -55 μA, and images were output under the following conditions.

[0112] The ID on the paper was then measured, and the ID differences between the four corners and the center of the square were judged as density unevenness, and the median value was judged. NN environment (temperature: 25℃, humidity: 50%) Paper (Sharp Corporation, PPC paper, model: SF-4AM3) Transfer belt toner adhesion amount (black 0.45 to 0.5 mg / cm2) Solid image (center of page, square 50mm high x 50mm wide)

[0113] Excellent: (ID: 1.40 or higher and density unevenness less than 0.05) Good: (ID: 1.40 or higher and density unevenness 0.05 or higher) Available: (ID: less than 1.40 and density unevenness less than 0.05) Bad (unacceptable): (ID: less than 1.40 and density unevenness 0.05 or more)

[0114] The method for measuring the fluidity of the toner is as follows.

[0115] The weight of 30 ml of toner was measured in 180 seconds using a bulk density measuring device (manufactured by Ito Seisakusho Co., Ltd., JIS-K-5101), and the bulk density of the toner was taken as the flowability value.

[0116] The adhesive strength of the external additive to the toner particles is as follows.

[0117] The adhesion strength of each external additive to toner particles (toner base particles) was measured using the following procedures (1) to (7). Note that the silica in the expression "silica adhesion strength" does not refer to silica added to the core of the fine powder, but to silica added as an external additive to the toner (not part of the fine powder).

[0118] (1) 2.0 g of toner is added to 40 ml of a 0.2% by mass Triton (polyoxyethylene octylphenyl ether) aqueous solution, and the mixture is stirred for 1 minute. (2) The above aqueous solution is irradiated with ultrasonic waves using an ultrasonic homogenizer (manufactured by Nippon Seiki Seisakusho Co., Ltd., model: US-300T) (output: 40 μA, 4 minutes). (3) After the ultrasonic irradiation, the aqueous solution is left to stand for 3 hours, and the toner and the liberated external additives are separated. (4) After removing the supernatant, add approximately 50 ml of purified water to the precipitate and stir for 5 minutes. (5) The solution is subjected to suction filtration using a membrane filter (manufactured by Advantec) with a pore size of 1 μm. (6) The toner remaining on the filter is vacuum dried overnight. (7) Using a fluorescent X-ray analyzer (Rigaku Corporation, model: ZSX Primus II), the intensity of the element (Si) in the external additive of 1 g of toner before and after the series of processes (1) to (6) above is analyzed, and the adhesion strength of the external additive to the toner particles is calculated using the following formula. Silica adhesion strength (%) = {(Si strength after treatment) / (Si strength before treatment)} × 100

[0119] The conditions and results of Examples 1 to 11 and Comparative Examples 1 to 4 are shown in Table 1.

[0120] [Table 1]

[0121] All of the examples showed excellent filming and transferability, and there were differences in superiority among the examples.

[0122] In Example 1, the particle size of external additive A was as large as 85 nm, resulting in the best results in filming and transferability. In Example 2, the particle size of external additive A was larger than in Example 1, resulting in worse filming. In Example 3, the particle size of external additive A was smaller than in Example 1, resulting in worse transferability and worse slip-through. In Example 4, the degree of association of external additive B was larger than in Example 1, resulting in worse filming.

[0123] In Example 5, the particle size of external additive B was smaller than that of Example 1, so filming worsened. In Example 6, the particle size of external additive B was larger than that of Example 1, so filming and transferability worsened, and slip-through worsened. In Example 7, the weight parts of external additive A and external additive B were smaller than those of Example 1, so transferability worsened.

[0124] In addition, in Example 8, the weight parts of external additive A and external additive B were larger than in Example 1, so filming worsened. In Example 9, the ratio of external additive A was smaller than in Example 1, so filming worsened.

[0125] In addition, in Example 10, the ratio of external additive A was larger than in Example 1, so the slip-through was worse. In addition, in Example 11, the bulk density was smaller than in Example 1, so the transferability was worse.

[0126] In all comparative examples in which the external additive did not contain A or B, filming and transferability were poor. Filming occurred in comparative example 1, in which the external additive contained only associated silica. Furthermore, slip-through occurred in comparative example 2, in which the external additive contained only organic-inorganic composite fine particles.

[0127] Comparative Examples 3 and 4, in which spherical silica was added, showed a slight improvement in transferability, but were not as good as those of the Examples.

[0128] As described above, the toner and image forming apparatus according to the present disclosure can reduce slip-through from the blade and reduce filming.

[0129] Although each embodiment and each example of the present disclosure have been described in detail above, it will be readily apparent to those skilled in the art that many modifications are possible without substantially departing from the novel features and effects of the present disclosure. Therefore, all such modifications are intended to be included within the scope of the present disclosure.

[0130] For example, a term described at least once in the specification or drawings together with a different term having a broader or similar meaning can be replaced with that different term anywhere in the specification or drawings. Furthermore, the configurations and operations of the toner and image forming apparatus are not limited to those described in the embodiments and examples of the present disclosure, and various modifications are possible. [Explanation of symbols]

[0131] 1 toner, 10 toner particles, 20 External additives, 21 Organic-inorganic composite particles, 22 Polymers, 23 Inorganic materials, 24 Associated silica, 30 cleaning unit (cleaner), 30a cleaning blade, 30b recovery casing, 31 exposure unit (semiconductor laser), 32 charging unit (charging roller), 33 developing unit (developer), 33a developing roller, 33b casing, 34 transfer unit (transfer charger), 35 fixing unit (fixer), 35a heating roller, 35b pressure roller, 37 separation unit, 38 housing, 40 (electrophotographic) photoreceptor, 50 Image forming unit, 100 Image forming device

Claims

1. A toner comprising toner particles and an external additive attached to the surfaces of the toner particles, the toner particles include a crystalline polyester resin and a wax; the external additive contains organic-inorganic composite fine particles and associated silica in which two or more primary particles are associated with each other, The toner has a softening point of 110° C. or less.

2. 2. The toner according to claim 1, wherein the organic-inorganic composite fine particles have a particle diameter of 70 to 200 nm.

3. 2. The toner according to claim 1, wherein the degree of association of the associated silica is 2.0 to 3.

0.

4. 2. The toner according to claim 1, wherein the particle diameter of the associated silica is 100 to 300 nm.

5. 2. The toner according to claim 1, wherein the amount of the external additive added to the toner particles is 1.0 to 1.2 parts by weight.

6. 2. The toner according to claim 1, wherein the organic-inorganic composite fine particles are contained in an amount of 75 to 90 wt % relative to the external additive.

7. 2. The toner according to claim 1, wherein the particle diameter of the organic-inorganic composite fine particles is smaller than the particle diameter of the associated silica.

8. 2. The toner according to claim 1, wherein the toner has a bulk density of 0.38 or more.

9. 2. The toner according to claim 1, wherein the adhesive strength of the external additive to the toner particles is 70% or less.

10. The toner according to any one of claims 1 to 9, an electrophotographic photoreceptor; an image forming unit; An image forming apparatus comprising:

Images