JP5622620B2 - Fixing apparatus and image forming apparatus having the same - Google Patents

Description

  The present invention relates to a toner used in an electrophotographic image forming apparatus such as a copying machine, a printer, and a facsimile machine, a fixing device, and an image forming apparatus including the fixing device.

  An electrophotographic image forming apparatus (for example, a printer) includes a fixing device that fixes a toner image formed on a recording medium (recording paper or paper) onto the paper by heat melting. As an example of this fixing device, a roller pair type fixing device including a fixing roller and a pressure roller is known (Patent Document 1).

The fixing roller is a roller member in which an elastic layer is formed on the surface of a hollow metal core made of metal such as aluminum, and a halogen lamp is arranged as a heat source inside the core metal.
The fixing roller is provided with a temperature control device, and the fixing roller is controlled by turning on / off the power of the halogen lamp based on a signal output from a temperature sensor provided on the surface of the fixing roller. The surface temperature is controlled.

  The pressure roller is a roller member in which a heat-resistant elastic layer such as silicon rubber is provided as a coating layer on a cored bar. The pressure roller is pressed against the peripheral surface of the fixing roller, and a nip region is formed between the fixing roller and the pressure roller by elastic deformation of the elastic layer of the pressure roller.

  In the above configuration, the fixing device sandwiches the paper on which the unfixed toner image is formed in the nip region between the fixing roller and the pressure roller, and conveys the paper by rotating both the rollers, The toner image on the sheet is melted and fixed on the sheet by the heat of the peripheral surface of the fixing roller.

However, in the above roller pair system, since the fixing roller and the pressure roller are in a room temperature state before the electrophotographic image forming apparatus is turned on, it is necessary to heat the fixing roller to a predetermined temperature after the power is turned on. Therefore, warm-up time is required.
Further, even in a standby state where the copying operation is not performed, in order to keep the roller surface at a predetermined temperature, the heating must always be performed even when the copying operation is not performed.
Therefore, in the electrophotographic image forming apparatus having the above-described roller resistance method, useless energy is consumed in addition to the copying operation.

In order to solve the above problem, there is known a pressure fixing type fixing device that fixes a toner only with a high pressure of 1 Mpa or more by a non-heating method (Patent Document 2).
However, since the toner is broken and fixed only by pressure, the toners do not melt, and the adhesion to paper fibers is weak, so there is a problem that sufficient fixing strength cannot be obtained. .

  In order to solve the problem, a resin that cures by mixing a plurality of liquids is used for a microcapsule having a double structure containing a microcapsule. A toner for pressure fixing, wherein a resin is encapsulated in a microcapsule that encloses the encapsulated microcapsule, and encloses the encapsulated microcapsule when pressure is applied by a fixing device. It has been disclosed that the resin that flows out of the first and second capsules after the second capsule is destroyed is mixed and cured, so that the fixability is improved (Patent Document 3).

Japanese Patent Laid-Open No. 11-38802 JP 58-21282 A JP 7-168351 A

However, in Patent Document 3, the liquid of the two-component mixed curable resin is enclosed in a double-structure toner capsule, but it is very difficult to make the capsule thickness uniform over the entire circumference. . Therefore, there is a problem that the liquid leaks from the thin film portion, and the two liquids are mixed and cured in the developing tank.
In addition, since the two liquids are sealed in two capsules, the thickness of the toner surface is reduced, the mechanical force such as stirring in the developing tank is weak, and the adhesive liquid leaks from the toner. is there.

  Accordingly, the present invention provides a pressure-fixing toner in which a two-liquid mixed type adhesive is not mixed and cured by a mechanical external force such as stirring in a developing tank, and the adhesive liquid does not leak from the toner. This is the issue.

  As a result of intensive efforts to solve the above problems, the present inventor has the toner containing the first component of the two-component mixed adhesive and the second component containing the second component. The present inventors have found that the above problems can be solved and have completed the present invention.

  Thus, according to the present invention, the toner containing at least the colorant contains the first component of the two-type mixed adhesive, and the toner external additive contains the second component of the adhesive. A pressure-fixing toner is provided.

  Further, according to the present invention, there is provided a toner wherein the first component is an epoxy resin prepolymer obtained by condensation polymerization of bisphenol A and epichlorohydrin, and the second component is an amine curing agent. The

  According to the invention, the toner and the external additive are microcapsule particles, and the toner has an average particle size of 4 to 13 μm and is larger than the average particle size of the external additive. There is provided a toner having a film thickness, wherein the external additive has an average particle diameter of 100 nm to 3 μm.

According to the present invention, the fixing device for fixing the toner fixes the toner while loading a biaxial roller with a predetermined pressure, and the load is 100 to 1000 kgf. However, a fixing device that is a non-heating type or a heating type having a fixing temperature of 30 to 100 ° C. is provided.
Furthermore, according to the present invention, there is provided an image forming apparatus using the above toner or provided with the above fixing device.

  The present invention has been made in view of the above problems. In an electrophotographic toner, an adhesive resin that cures when a plurality of solids are mixed is used to enclose one of the resins in the center of the toner. One resin is used as an external additive on the toner surface. With this configuration, when the toner is fixed at a predetermined pressure, the capsule in the toner is broken and is cured by coming into contact with the second adhesive resin externally added to the toner surface. Since only one adhesive resin is present in the toner, the thickness of the toner surface can be made sufficient. In addition, since the other adhesive resin is externally added to the toner surface, there is an opportunity for sufficient contact when the first adhesive resin in the toner is exposed due to the destruction of the capsule. It is possible to obtain sufficient curing by mixing.

In the toner according to the present invention, even when mechanical stress is applied in the developing tank, the first component and the second component are difficult to contact and mix and do not cure, so the toners do not aggregate. However, if a strong pressure is applied in the fixing step, the toner external additive is destroyed and the two liquids are mixed, thereby enabling strong fixing.
The toner according to the present invention further increases the strength of the toner and the external additive against external stress by using the toner and the external additive as microcapsules.

  In general, when the number of printed sheets of the multi-function peripheral is increased, the toner external additive in the developing tank may be embedded in the toner due to mechanical stress. In this case, if the thickness of the capsule in the toner is smaller than the average particle diameter of the capsule particles on the toner surface, the first component of the two-type mixed adhesive in the toner and the second component in the embedded external additive May contact and harden.

However, since the toner according to the present invention is a microcapsule particle having a film thickness larger than the average particle diameter of the external additive, it has an effect of not causing the above problem.
Furthermore, it is excellent in water resistance, electrical insulation, etc., and enables stable development.

  If the average particle size of the microcapsules that are the toner and the external additive is too small, it is difficult to break the microcapsules even when a strong pressure is applied. Further, if the average particle size is too large, the external additive tends to be detached from the toner surface and causes scattering from the developing tank. However, the toner according to the present invention and the microcapsule that is the external additive are suitable respectively. Since it has a particle diameter, the capsule in the toner and the capsule in the external addition can be completely broken by a sufficient load.

Further, by using a two-component mixed type adhesive for the toner, the fixability, which has been a problem of pressure fixing, can be made sufficient. Therefore, sufficient fixability can be realized even without heating, and energy saving can be achieved.
Further, by fixing with heating and pressure at 30 to 100 ° C., the capsule can be surely broken, and the toner can be reliably fixed.

1 is a schematic cross-sectional view of an image forming apparatus according to the present invention. FIG. 3 is a schematic cross-sectional view of toner particles according to the present invention. FIG. 3 is a schematic cross-sectional view of a fixing roller according to the present invention.

The toner according to the present invention includes a first component of a two-type mixed adhesive (also referred to as a two-component mixed curable resin), and an external additive externally added to the toner includes a second component. (See FIG. 2).
Therefore, the term “external additive” used in the present invention means a microcapsule particle containing one component of the above-mentioned two-mixed type adhesive, more specifically, an amine-based curing agent.

  One embodiment of the present invention will be described with reference to FIGS. 1 to 3 as follows. In the present embodiment, the image forming apparatus of the present invention is applied to a color multifunction peripheral, and FIG. 1 is a schematic configuration diagram of the color multifunction peripheral.

  As shown in FIG. 1, a color multifunction peripheral 100 according to the present embodiment includes an optical system unit E, four sets of visible image forming units pa, pb, pc, pd, an intermediate transfer belt 11, and a secondary transfer unit 14. A fixing unit 15, an internal paper feeding unit 16, and a manual paper feeding unit 17.

In the visible image forming unit pa, a charging unit 103a, a developing unit 102a, and a cleaning unit 104a are arranged around a photosensitive drum 101a serving as a toner image carrier.
The primary transfer unit 13 a is disposed via the intermediate transfer belt 11. The other three sets of visible image forming units pb, pc, and pd have the same configuration as the visible image forming unit pa, and the developing units of each unit are yellow (Y), magenta (M), and cyan (C), respectively. And black (B) toner.

The optical system unit E is arranged so that the data from the light source 4 reaches the four sets of photosensitive drums 101a, 101b, 101c, and 101d.
The intermediate transfer belt 11 is disposed without being bent by the tension rollers 11a and 11b, and the waste toner box 12 is disposed on the tension roller 11b side, and the secondary transfer unit 14 is disposed on the tension roller 11a side.
The fixing unit 15 includes a fixing member 15 a and a conveying member 15 b and is disposed downstream of the secondary transfer unit 14.

The image forming process is as follows. After the surface of the photosensitive drum 101a is uniformly charged by the charging unit 103a, the surface of the photosensitive drum 101a is laser-exposed according to image information by the optical system unit E to form an electrostatic latent image.
As the charging unit 103a, a charging roller system is employed to charge the surface of the photosensitive drum 101a uniformly and without generating ozone as much as possible. Thereafter, the developing unit 102a develops a toner image on the electrostatic latent image on the photosensitive drum 101a, and the visualized toner image is intermediated by a primary transfer unit 13a to which a bias voltage having a polarity opposite to that of the toner is applied. Transfer onto the transfer belt 11. The other three sets of visible image forming units pb, pc, and pd operate in the same manner and are sequentially transferred onto the intermediate transfer belt 11.

The toner image on the intermediate transfer belt 11 is conveyed to the secondary transfer unit 14 and is separately supplied to a recording sheet fed from the sheet feeding roller 16a of the internal sheet feeding unit 16 or the sheet feeding roller 17a of the manual sheet feeding unit 17. The toner is transferred by applying a bias voltage having a polarity opposite to that of the toner.
The toner image on the recording paper is conveyed to a fixing unit and is generally heated by laser irradiation and fused onto the recording paper. In the present invention, the toner image is pressed by a fixing device composed of a fixing roller and a pressure roller. Fixed and discharged to the outside.

Next, the pressure fixing device of the present invention will be described in detail with reference to FIG.
The pressure fixing device includes a fixing roller and a pressure roller, and can apply a load of 100 to 1000 kgf.

In this embodiment, a load of 500 kgf is applied to the pressure fixing device. Both the fixing roller and the pressure roller are hollow cylindrical, are made of 40φ iron material, and have a hard chrome plated surface.
Although no halogen lamp is arranged in the fixing roller, a heating means such as a halogen lamp may be provided in order to improve the fixing property.

  By applying a high load of 100 to 1000 kgf to the fixing roller and the pressure roller, the toner is deformed, the toner microcapsules and the external additive microcapsules are destroyed, and the two liquids are mixed together. It can be fixed.

  The image forming apparatus of this example was used with the maximum fixing speed set to 225 mm / second and the maximum copying speed set to 50 sheets / minute (A4 horizontal feed).

  An unfixed toner image is, for example, a toner contained in a developer such as a non-magnetic one-component developer containing non-magnetic toner, a non-magnetic two-component developer containing non-magnetic toner and carrier, and a magnetic developer containing magnetic toner. Formed with.

The toner according to the present invention encloses one of two types of adhesives in the toner. Further, an encapsulated external additive containing the other adhesive is externally added to the toner surface.
When the adhesive is solid, it is not necessarily encapsulated.
As a combination of the components of the two-type mixed adhesive, there is a combination of a polyol and a polyisocyanate as a urethane resin adhesive, or a urethane polymer having an isocyanate group at a terminal and a polyol.

Epoxy resin adhesives include a combination of an epoxy resin prepolymer obtained by condensation polymerization of bisphenol A and epichlorohydrin and an amine curing agent.
Examples of the modified silicone adhesive include a combination of a mixture of an epoxy resin and an organic catalyst and a mixture of a molded silicone resin and a curing agent for epoxy resin.
However, the two-type mixed adhesive is not limited to the above-mentioned adhesive, and any adhesive that can be cured and bonded by mixing two liquids may be used.
Since the two-type mixed adhesive used in the toner of the present invention is cured at room temperature by mixing two components, it does not require heating of a fixing roller or the like, and can be sufficiently fixed only by pressure. Have

  As a method for encapsulating, a known technique can be used. For example, toner microcapsules and external additive microcapsules can be produced by an S / O microcapsule method, a phase separation method, an interfacial polymerization method, an in-situ polymerization method, a spray drying method, or the like.

  In the following examples, an interfacial polymerization method is employed for the production of toner microcapsules and external additive microcapsules. A mixing device such as a Henschel mixer is used as a method of externally adding an external additive microcapsule encapsulating the second component to the surface of the toner microcapsule encapsulating the first component of the two-type mixed adhesive.

Examples of the colorant include carbon black, aniline black, acetylene black, naphthol yellow, Hansa yellow, rhodamine lake, alizarin lake, Bengala, phthalocyanine blue, and indanthrene blue.
One type of colorant may be used alone, or two or more types may be used in combination. The colorant is appropriately selected according to the color required for the toner.

Examples of the outer layer of the toner that is a shell portion, that is, a microcapsule, include melamine-formaldehyde resin, polyester resin, and styrene acrylic resin. The resin is not limited to this, and a known resin used as a binder resin for the toner can be used.
One of these resins may be used alone, or two or more thereof may be used in combination.

The core portion or the shell portion of the toner microcapsule may contain a release agent.
By including a release agent in the core portion, it is possible to impart releasability to the toner when the toner is fixed on the recording medium, so that the releasability to the fixing roller is higher than when no release agent is used. Can be improved.

Examples of release agents include paraffin wax, ester wax, polyolefin wax, polyurethane wax such as low molecular weight polyurethane, wax such as carnauba wax (carnauba wax), microcrystalline wax, jojoba wax, rice wax, and montanic acid wax. Is mentioned.
A mold release agent may be used individually by 1 type, and 2 or more types may be used together.

A charge control agent may be contained in the core portion or the shell portion of the toner microcapsule.
By containing the charge control agent in the core portion or the shell portion, the charging characteristics of the toner can be controlled. Examples of the charge control agent include quaternary ammonium compounds, metal complexes of monoazo dyes, nitrohumic acid and salts thereof, metal complexes with metals such as salicylic acid, chromium or iron, and amino compounds.
A material known as an organic dye can also be used as a charge control agent.
One charge control agent may be used alone, or two or more charge control agents may be used in combination.
The toner microcapsules according to the present invention have an average particle diameter of 4 to 13 μm.

The paper transport device includes a transport belt, a drive roller, a driven roller, a suction charger, a separation charger, a charge removal charger, a separation claw, and a drive motor. The conveying belt is made of polyimide resin having a belt thickness of 75 μm and a volume resistivity of 10 ¹⁶ Ω · cm, and is stretched between a driving roller and a driven roller. The driving roller is configured to be driven to rotate at an arbitrary speed by a driving motor (not shown), and the conveyor belt rotates at an arbitrary speed in the direction of the arrow by the rotation of the driving roller.

  In addition, an adsorption charger, a separation charger, a charge removal charger, and a separation claw are provided around the conveyor belt. In such an apparatus, the sheet on which the unfixed toner image conveyed from the secondary transfer unit is conveyed is conveyed between the conveyance belt on the driven roller and the suction charger. The driven roller is made of a conductive material and is grounded. When a charge is applied to the paper by the suction charger, the paper and the transport belt cause dielectric polarization, and the paper is electrostatically attracted onto the transport belt.

  The sheet is conveyed to the laser irradiation unit by driving the driving roller. The unfixed toner image on the paper conveyed to the laser irradiation unit is irradiated with a laser according to the image information by the laser head and fixed. The paper on which the fixing of the toner image in the laser irradiation unit has been completed is conveyed between the separation charger and the driving roller while being electrostatically attracted to the conveyance belt.

  The driving roller is made of a conductive material and is grounded, and the electrostatic adsorption force between the conveyance belt and the paper is weakened by removing the charge on the paper with a separation charger. In this state, the conveyance belt rotates along the driving roller and has a large curvature, so that the leading edge of the sheet floats from the conveyance belt, and the sheet is completely separated from the conveyance belt by the separation claw. The transport belt from which the paper has been peeled is driven to the suction position of the paper again after the outer surface and the inner surface are discharged by the charge removal charger.

Example 1
<Toner>
FIG. 2 shows a toner to which the present invention is applied. The toner is a microcapsule (shell 1) having a core-shell structure that includes a first component of a two-component mixed adhesive as a core. Further, the microcapsule which is the toner holds an external additive (shell 2) containing a second component of the two-component mixed adhesive on the surface thereof.
In FIG. 2, the shell is a single layer, but it may be composed of a plurality of layers so as not to be broken by a mechanical external force in the developing tank.

  In this embodiment, the core shell is formed by an interfacial polymerization method or the like, but is not limited to these manufacturing methods.

  As the core component, at least 10 g of an epoxy resin obtained by condensation polymerization of bisphenol A and epichlorohydrin and 0.2 g of carbo black are mixed, and 0.5 g of terephthaloyl dichloride is added thereto and dissolved. The dissolved component was added to 100 ml of 1% aqueous protective colloid solution and emulsified.

  Next, 8 g of 4% hexamethylenediamine aqueous solution and 3 g of 12% sodium hydroxide aqueous solution were added to the emulsified solution. As soon as both solutions were mixed, an interfacial polymerization reaction occurred at the interface between the oil phase and the aqueous phase, and a shell was formed. Thereafter, the pH was adjusted to 4-5.

A solution in which 2 g of melamine and 3 ml of formalin were dissolved in a solution adjusted to pH 9 by adding 0.04 mg of sodium hydroxide to 100 ml of water in advance was added. As the temperature was raised, the polymerization reaction proceeded and melamine-formaldehyde resin was gradually formed on the surface of the core. When stirring was performed at about 80 ° C. for 5 hours, the reaction was almost complete and a shell was formed. The pH was adjusted to 8, and after cooling, 10 g of toner was obtained. In this case, filtration may be performed as necessary.
When the obtained toner was measured with an electron microscope (SEM), the average particle radius of the toner was 10 μm, and the thickness of the shell was 3 μm.

<Creation of external additives>
Also in this case, it is prepared by the interfacial polymerization method as described above. As the core component, 0.4 g of terephthaloyl dichloride is dissolved in 10 g of the amine curing agent. The left component was added to 100 ml of 1% aqueous protective colloid solution and emulsified.

  Next, 8 g of 4% hexamethylenediamine aqueous solution and 3 g of 12% sodium hydroxide aqueous solution are added to the emulsified solution. As soon as both solutions were mixed, an interfacial polymerization reaction occurred at the interface between the oil phase and the aqueous phase, and a shell was formed. Once the core was formed, the pH was adjusted to 4-5.

  A solution in which 2 g of melamine and 3 ml of formalin were dissolved in a solution adjusted to pH 9 by adding 0.04 mg of sodium hydroxide to 100 ml of water in advance was added. As the temperature is raised, the polymerization reaction proceeds and melamine-formaldehyde resin is gradually formed on the surface of the core. When stirring is performed at about 70 ° C. for 2 hours, the reaction is almost completed and a shell is formed. The pH was adjusted to 8, and after cooling, 9 g of external additive was obtained. At this time, filtration may be performed as necessary.

When the obtained toner was measured with an electron microscope (SEM), the average particle radius was 2 μm in this example.
In the above toner production method, the interfacial polymerization method is used. However, the production method is not limited to the above production method, and any known method may be used as long as it can be encapsulated.

  The toner before external addition obtained by the above method and the external additive are mixed with a mixer. Specifically, 2 g of external additive and 0.1 g of silica R202 were stirred at 1000 rpm for 30 seconds with respect to 10 g of toner.

  When the toner prepared as described above was passed through a pressure fixing device composed of the fixing roller and the pressure roller shown in FIG. 3 and pressurized with a load of 500 kgf without heating, the fixing strength was sufficient and good fixing was obtained.

Example 2
The toner was the same as in Example 1, and the fixing strength was further increased as a result of setting the fixing device temperature to 70 ° C.

  According to the present invention, a pressure fixable toner in which a two-component mixed type adhesive is not mixed and cured by a mechanical external force such as stirring in a developing tank, and the adhesive liquid does not leak from the toner, the toner Fixing device and an image forming apparatus including the fixing device are provided.

4: Light source 11: Intermediate transfer belt 11a: Tension roller 11b: Tension roller 12: Waste toner BOX

13a: primary transfer unit 14: secondary transfer unit 15: fixing unit 15a: fixing member 15b: transport member 16: internal paper feeding unit 16a: paper feeding roller

17: Manual paper feed unit 17a: Paper feed roller 100: Color multifunction peripheral 101a: Photoconductor drum 101b: Photoconductor drum 101c: Photoconductor drum 101d: Photoconductor drum

102a: development unit 102b: development unit 102c: development unit 102d: development unit 103a: charging unit 103b: development unit 103c: development unit 103d: development unit

104a: Cleaning unit 104b: Cleaning unit 104c: Cleaning unit 104d: Cleaning unit E: Optical system unit pa: Visible image forming unit pb: Visible image forming unit pc: Visible image forming unit pd: Visible image forming unit

Claims (6)

Toner containing at least a colorant, encapsulating the first component of the two-kind mixed type of adhesive, the toner external additive, wherein a pressure fixing toner you containing a second component of the adhesive,
The toner and the external additive are microcapsule particles,
The toner is microcapsule particles having an average particle diameter of 4 to 13 μm and a film thickness larger than the average particle diameter of the external additive;
The pressure-fixing toner, wherein the external additive has an average particle diameter of 100 nm to 3 μm .   The toner according to claim 1, wherein the first component is an epoxy resin prepolymer obtained by condensation polymerization of bisphenol A and epichlorohydrin, and the second component is an amine-based curing agent. An image forming apparatus using a toner according to claim 1 or 2. The image forming apparatus, a toner according to claim 1 or 2, the roller of the two axes is fixing the toner while the load at a predetermined pressure, and Fixing the load Ru 100~1000kgf der The image forming apparatus according to claim 3, comprising the apparatus. The image forming apparatus, an image forming apparatus according to claim 3 or 4 comprising a non-heating type fixing device. The image forming apparatus, a heating fixing includes a device, an image forming apparatus according to any one of claims 3-5 fixing temperature is 30 to 100 ° C..