JP3581046B2 - Seamless belt - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a seamless belt used for an electrophotographic copying machine, a laser printer, or the like, and more particularly, to a seamless belt for a photoreceptor substrate, for intermediate transfer, for paper conveyance, for development, or for fixing. It is about improvement.
[0002]
[Prior art]
In recent years, with the commercialization of electrophotographic copiers such as full-color copiers, when transferring a toner image developed on a photoreceptor to copying paper, the toner is first transferred to an intermediate transfer body and then transferred to the copying paper. The process is adopted. In this process, a toner image is formed on the surface of the photosensitive drum by a developing device, and the toner image is transferred to a seamless belt, which is an intermediate transfer member below the photosensitive drum, and then the toner image on the seamless belt is transferred to the seamless belt. Is transferred to a copy sheet sandwiched between the sheet and the secondary transfer roller. As described above, the seamless belt is used as an intermediate transfer member, but is not limited to this, and its use is also being considered for a photoreceptor and the like.
[0003]
Conventionally, a seamless belt is formed of a plastic material in a region called conductive or semiconductive for reasons such as good moldability and light weight. Such a conductive or semiconductive seamless belt is disclosed, for example, in Japanese Patent Application Laid-Open No. 10-226028. The conductivity imparted to the seamless belt of any material is in the range of 1 to 1 × 10 ¹³ Ω / □ based on the surface resistivity. This is because, if the surface resistivity exceeds the range of 1 to 1 × 10 ¹³ Ω / □, the volume resistance generally increases, and the important and basic performances of toner conveyance and transfer cannot be satisfied. is there.
[0004]
[Problems to be solved by the invention]
As described above, the conventional seamless belt has the conductivity in the range of 1 to 1 × 10 ¹³ Ω / □ based on the surface resistivity, and secures the important and basic performance of toner conveyance and transfer. I have. However, such a surface resistivity has no particular problem when printing on copy paper, but when printing on a plastic sheet for OHP, the sheet cannot be transported, and satisfactory performance cannot be obtained at all. There is a big problem that.
[0005]
SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a seamless belt that can be expected to have sufficient conductivity for toner transport and transfer performance, and that can transport OHP sheets and the like. The purpose is.
[0006]
[Means for Solving the Problems]
In the present invention, in order to achieve the above object, a resin material solution in which a carbon filler is dispersed in a resin material is poured into a mold, rotated, and formed into an endless piece having a thickness of 0.02 to 0.5 mm by centrifugal molding. That is
The relationship between the surface resistivity ρs (Ω / □) and the volume resistivity ρv (Ω · cm) outside the peripheral surface is 109 ≧ ρs / ρv ≧ 40, and the surface resistivity ρs (Ω / □) is 2 × 10 ¹³ (Ω / □) or more.
[0007]
That is, in order to obtain a seamless belt capable of transporting OHP sheets and the like having sufficient conductivity at the time of transporting and transferring the toner, the present inventors require an insulating area on the outer peripheral surface. Focusing on the fact that it is sufficient to have the resistance value of the conductive or semiconductive region as a whole, and as a result of various studies on the method and configuration, the toner The present invention was completed by confirming that a seamless belt capable of transporting an OHP sheet or the like was obtained, which satisfied transfer performance.
[0008]
According to the present invention, since the whole is a seamless belt having a resistance value of a conductive or semiconductive region and a resistance value of an insulating region on the outer surface of the peripheral surface, it is referred to as toner conveyance, transfer and the like. It is possible to convey a sheet for OHP or a substrate to be printed which is recognized to be substantially similar to the sheet, which satisfies performance.
That is, while the substrate to be printed is transported by utilizing the electrostatic attraction force generated between the seamless belt and the substrate to be printed, the plastic material forming the OHP sheet and the like and the resin forming the seamless belt are used. Since the charging sequence of the material is close, if the outer surface of the peripheral surface shows the resistance value of the conductive or semiconductive region, a sufficient electrostatic attraction force will not be developed. According to the present invention, since the outer surface of the peripheral surface has the resistance value of the insulating region, even if the charging lines are close to each other, natural attenuation of static electricity is small and sufficient electrostatic attraction force is exhibited. Therefore, it is possible to convey an OHP sheet or the like made of a plastic material.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiment.
As shown in FIG. 1, the seamless belt according to the present embodiment is endlessly centrifugally molded to a thickness of 0.02 to 0.5 mm obtained by adding and dispersing a carbon filler to a resin material, and is formed into a circumferential shape in contact with an OHP sheet (not shown). The relationship between the surface resistivity ρs (Ω / □) and the volume resistivity ρv (Ω · cm) of the outer surface 1a is set to 109 ≧ ρs / ρv ≧ 40 , and the surface resistivity ρs (Ω / □) is It is set to 2 × 10 ¹³ (Ω / □) or more.
[0010]
As the resin material, a known material is used, but since the seamless belt 1 is used while being supported by a plurality of rolls, a material having sufficient mechanical strength and flexibility is selected. Examples of such materials include polyester resins such as PET, PBT, and PEN, polyimide resins, polyamideimide resins, polyamide resins, fluororesins, polysulfone, aramid resins, and polyetheretherketone. The resin material may be either thermosetting or thermoplastic, but an appropriate material can be selected depending on the manufacturing method used.
[0011]
Examples of the carbon filler include Ketjen black, acetylene black, oil furnace black and the like. These carbon blacks play an important role in obtaining the required properties depending on the state of dispersion. To explain this point in detail, the seamless belt 1 is formed as thin as about 0.02 to 0.5 mm in order to secure flexibility. When carbon black is agglomerated in this, the agglomerated particles are in a state having an aspect ratio other than 1 and an aspect ratio of 1.5 or more. When it is applied, a moment is generated, and it is easy to orient in the plane direction. As a result, the resistance in the plane direction is lower than the resistance in the thickness direction, and particularly when the volume resistivity is about 1 × 10 ⁶ to 1 × 10 ¹³ Ω · cm, the delicate orientation is large in the directionality of the resistance. Affect.
[0012]
Therefore, in the present embodiment, the ratio of the secondary aggregated particles of carbon black is set to 20% by weight or less, preferably 10% by weight or less, more preferably 5% by weight or less based on the total amount of the carbon filler. Thereby, it is possible to suppress the surface resistivity from unnecessarily lowering in order to obtain the required volume resistivity.
[0013]
The method of measuring the ratio of the aggregated particles in all the carbon particles depends on the method of measuring the particle diameter of the carbon particles. That is, with respect to the primary particle diameter of a certain carbon particle, the particle diameter of the aggregated particles showed a large value at a level of several times to several tens times or more, and showed a particle diameter more than twice the primary particle diameter in the particle size distribution. The particles are secondary aggregated particles, and the ratio to the total amount of the particles may be calculated.
[0014]
According to this measuring method, about 50% or more of the commercially available carbon filler is secondary aggregated, and it is necessary to perform a treatment for breaking up the secondary aggregation. As shown in FIGS. 2 (a), 2 (b), 2 (c), and 2 (d), the gap at the minimum portion of the flow path is 0.1 mm or less, and separation and collision of the liquid agent are not performed. A method of passing through the static mixer 2 is performed. The static mixer 2 includes a pair of upper and lower metal molds, and a groove 4 is formed in a lower mold 3. In the static mixer 2, when the upper die 5 and the lower die 3 are clamped, the groove 4 becomes a flow path, and the material containing the carbon filler that has flowed in from one side is separated and collides while the material containing the carbon filler is discharged from the other. . In the examples of FIGS. 2A, 2B, 2C, and 2D, separation and collision are performed twice.
[0015]
Because the size of the primary particles of the carbon filler is very fine, from several to several hundred nm, the gap is too large or the crushing is carried out only stochastically with a commonly used method such as a ball mill or a three roll. It takes a long time to reduce the aggregated particles. However, if the static mixer 2 is used, the carbon particles passing through the static mixer 2 are always subjected to a crushing process, so that the carbon particles can be processed very efficiently.
[0016]
As a method of dispersing the carbon filler in the resin material, a method of mixing with the resin material after the secondary aggregation and disintegration treatment in an appropriate solvent, directly adding the carbon filler to the resin material, and then performing the disintegration treatment There is a way to do it. However, once mixed with the resin material, the particles once crushed may re-aggregate. Therefore, even if the crushing treatment is performed before mixing with the resin material, the particles are crushed again after mixing with the resin material. Processing is preferred.
[0017]
The amount of the carbon filler to be added to the resin material is appropriately determined according to the required conductivity, but is specifically selected from the range of 1 to 30 parts by weight based on 100 parts by weight of the resin material. In the present embodiment, care must be taken because the above-described crushing treatment does not have a conventional relationship between the surface resistivity and the volume resistivity.
[0018]
The surface resistivity of the outer peripheral surface 1a of the seamless belt 1 is calculated by a resistance value measured on the same surface, and the volume resistivity is calculated by a resistance value measured between the front and back surfaces of the seamless belt 1. Although the value obtained particularly by the measurement voltage changes depending on the method of measuring the resistance value, the seamless belt 1 according to the present invention has a surface resistivity and a surface resistivity of approximately 0.13 according to a method substantially conforming to the test method of 5.13 resistivity in JIS K 6911. The volume resistivity is calculated.
[0019]
As an apparatus for the measurement test, conductive rubber or moisture-permeable conductive paint cut in a hatched portion in FIGS. 3A and 3B, a power supply (dry cell or storage battery) with a DC voltage of 500 V, and FIG. Insulation resistance measuring device 6, appropriately insulated switch, outer micrometer specified in JIS B 7502 or equivalent or more accurate, vernier caliper with minimum reading of 0.02 mm specified in JIS B 7507 Alternatively, a device having a precision equal to or higher than this is used. As a test body, the formed seamless belt 1 is used as it is. The pretreatment of this specimen is performed at C-90 ⁺ _4-2 h / 20 ± 2 ° C./(65±5)% RH.
[0020]
In the measurement test method, first, the thickness of the treated specimen is accurately measured to 0.01 mm with an outer micrometer, and then conductive rubber is arranged and pressed on the specimen to form an electrode.
In addition, as shown in FIG. 3, an electrode can be formed by drawing a moisture-permeable conductive paint on the test sample. In this case, the specimen is treated after drawing the electrodes, and care is taken that the moisture-permeable conductive paint does not peel off the specimen during the operation.
The outer diameter of the inner circle of the surface electrode and the inner diameter of the ring electrode are measured with a vernier caliper to 0.02 mm, and the surface resistivity is measured as shown in FIG. Each connection is made as shown in FIG. This is further connected to the circuit position of the insulation resistance measuring device 6, charged for one minute, and the surface resistivity and the volume resistance are measured. In this case, the test is performed at a temperature of 20 ± 2 ° C. and a relative temperature (65 ± 5%).
[0021]
After measuring the surface resistivity and the volume resistivity, the surface resistivity and the volume resistivity are calculated by the following equations.
ρv = πd ² / 4t × R _V
ρs = π (D + d) / D−d × R _s
Where ρs: surface resistivity (MΩ)
ρv: Volume resistivity (MΩ · cm)
d: Outer diameter of inner circle of surface electrode (cm)
t: thickness of test specimen (cm)
R _V : Volume resistance (MΩ)
D: inside diameter of the annular electrode on the surface (cm)
R _s : surface resistance (MΩ)
π: Pi = 3.14
[0022]
Examples of the method for forming the seamless belt 1 include centrifugal molding, extrusion molding, and injection molding, and it is preferable to select a centrifugal molding method that is excellent in thickness accuracy, surface condition, and the like. Here, the centrifugal molding method is to form a layer of the fluid liquid on the inner peripheral surface of the mold by centrifugal force by injecting and rotating the fluid liquid composed of the above-described raw materials into a cylindrical mold. A method of removing a solvent or curing a reaction-curable resin to form a resin layer on the inner peripheral surface of a mold and remove the mold. The thickness of the seamless belt 1 is in the range of 0.02 to 0.5 mm. This is because the seamless belt 1 is used while being supported by a plurality of rolls, and if it is less than 0.02 mm, the mechanical strength is insufficient. Further, if it exceeds 0.5 mm, the flexibility is not sufficient.
[0023]
Next, a method of manufacturing the seamless belt 1 will be described. First, a resin material solution is prepared. Specifically, a resin material serving as a base is made into a solution with an appropriate solvent, and the carbon filler is dispersed by the above method. At this time, the viscosity of the resin material solution is adjusted to be 50,000 cp or less. If the viscosity exceeds 50,000 cp, it is difficult to level the inner peripheral surface of the mold 8 by centrifugal force. Although the lower limit is not particularly limited, it can be said that it is preferably 10 cp or more from the viewpoint of handling the resin material solution.
[0024]
After adjusting the resin material solution, as shown in FIG. 6, a required amount of the resin material solution is poured into a mold 8 arranged on a plurality of rotatable rollers 7. The mold 8 is formed in a cylindrical shape using metal, and the inner peripheral surface is mirror-finished or treated with a fluorine resin or a silicone resin, so that the seamless belt 1 can be easily removed from the mold. Metal or resin lids (not shown) are fitted to both ends of the mold 8 so that the injected resin material solution does not leak. This lid has a ring shape in the center of which is formed a hole for injecting a resin material solution. The resin material solution may be calculated from the concentration of the solution, the specific gravity of the solid content, the inner peripheral surface dimension of the mold 8, and the thickness of the product, and a predetermined amount may be injected. Since the seamless belt 1 of the present embodiment is required to have mechanical strength and flexibility, the thickness range is approximately 0.02 to 0.5 mm.
[0025]
Next, the mold 8 is initially slowly rotated, and the rotation speed is gradually increased while uniformly applying the resin material solution to the inner peripheral surface of the mold 8 to centrifugally mold the seamless belt 1. At this time, if the mold 8 is externally heated by a suitable heater as needed, the viscosity of the resin material solution can be reduced and the evaporation of the organic solvent can be promoted. However, since rapid drying adversely affects the surface state of the seamless belt 1, the heating of the mold 8 was initially lowered by about 120 to 50 ° C. below the boiling point of the resin solution, and a touch-dry state was obtained. The temperature may be increased later to complete the drying.
[0026]
When the centrifugal molding of the seamless belt 1 is completed in this way, the entire mold 8 is air-cooled. Then, the seamless belt 1 is naturally released from the inner peripheral surface of the mold 8 due to the difference in thermal expansion coefficient between the mold 8 and the polyamideimide constituting the seamless belt 1. If the seamless belt 1 and the inner peripheral surface of the mold 8 have a high degree of adhesion and do not spontaneously separate, the seamless belt 1 may be gradually separated from the end. Finally, by cutting to a predetermined width, the seamless belt 1 can be obtained.
[0027]
In the above embodiment, the relationship between the surface resistivity ρs (Ω / □) and the volume resistivity ρv (Ω · cm) of the outer peripheral surface 1a of the seamless belt 1 is set to 109 ≧ ρs / ρv ≧ 40 . In practice, it is preferable that the relationship between the surface resistivity ρs (Ω / □) and the volume resistivity ρv (Ω · cm) is set to 109 ≧ ρs / ρv ≧ 50 .
[0028]
【Example】
Hereinafter, Examples and Comparative Examples of the seamless belt 1 according to the present invention will be described.
Preparation of resin material solution Equivalent amount of trimellitic anhydride and 4,4'-diaminodiphenylmethane is dissolved in dimethylacetamide, and the mixture is heated and reacted to obtain a solid content (substantially completely closed polyamideimide) of 28% by weight of aromatic compound. A polyamide imide solution was obtained. Further, dimethylacetamide was added to obtain a polyamideimide solution having a solid content of 15% by weight and a specific gravity of the solid content of 1.2.
In all of the examples and comparative examples, this polyamideimide solution was used as a resin material solution.
[0029]
Example 1
As a carbon filler, "Special Black MONARCH 120" (particle size: 75 nm) manufactured by Cabot was mixed with dimethylacetamide to a concentration of 15% by weight, and this was mixed with Fig. 2 (a), (b), (c), (d). (2) Applying a pressure of 500 kgf / cm ² to a static mixer (flow path width 0.1 mm, depth 0.1 mm) 2 shown in (1) to pulverize the carbon filler to obtain a carbon filler mixed solution. When the carbon filler mixed solution was thus obtained, 20 parts by weight of the carbon black mixed solution was added to 100 parts by weight of the polyamideimide solution, and the mixture was again passed through the static mixer 2 to obtain a polyamideimide-carbon black mixed solution. When the particle size distribution at this time was measured by a laser diffraction method, the ratio of particles having a particle size exceeding 150 nm was 2.1 wt%.
[0030]
Next, a metal mold 8 having a ring-shaped lid having an inner diameter of 200 mm, an outer diameter of 220 m and a length of 400 mm and having a ring-shaped lid having an inner diameter of 170 mm and an outer diameter of 220 mm at both ends for preventing material leakage is rotated at a speed of 100 rpm. 215 g of a polyamideimide-carbon black mixed solution was injected into the mold 8. At this time, the atmosphere temperature was maintained at 80 ° C. by a hot air blower, and the rotation speed of the mold 8 was gradually increased to 1650 rotations. When this operation was continued for 30 minutes, the rotation of the mold 8 was stopped, and each mold 8 was put into an oven set at 180 ° C., and was taken out of the oven after 45 minutes. The polyamide-imide seamless belt 1 was removed from the mold 8 and cooled at room temperature to obtain a seamless belt 1 having a thickness of about 100 μm.
[0031]
Once the seamless belt 1 is obtained, a conductive rubber is formed in the shape and dimensions shown in JIS K 6911 5.13 section of resistivity, and this is pressed against the manufactured seamless belt 1 to form an electrode for a measurement test. 5.13 The surface resistance and the volume resistivity of the outer peripheral surface 1a were measured substantially in accordance with the resistivity test method, and the surface resistivity and the volume resistivity were calculated. As a result, the surface resistivity was 1.2 × 10 ¹⁴ (Ω / □), and the volume resistivity was 1.1 × 10 ¹² (Ω · cm).
The seamless belt 1 was incorporated as an intermediate transfer member of a color laser printer, and a print test was performed on plain paper and an OHP sheet. As a result, good results were obtained in all cases.
[0032]
Example 2
The same carbon black as in Example 1 was mixed with dimethylacetamide to a concentration of 15% by weight, and the mixture was stirred and mixed by a ball mill for 48 hours to obtain a carbon black mixed solution. After the carbon black mixed solution was thus obtained, 25 parts by weight of the carbon black mixed solution was added to 100 parts by weight of the polyamideimide solution, and the mixture was stirred and mixed with a ball mill for 24 hours to obtain a polyamideimide-carbon black mixed solution. When the particle size distribution at this time was measured by a laser diffraction method, the ratio of particles having a particle size exceeding 150 nm was 8.6 wt%.
Next, using the same apparatus as in Example 1, a seamless belt 1 having a thickness of 100 μm was obtained by the same method.
[0033]
Then, the surface resistivity and the volume resistivity of the outer peripheral surface 1a of the seamless belt 1 were calculated in the same manner as in Example 1, and were 6.5 × 10 ¹³ (Ω / □) and 1.6 × 10 ^{12, respectively.} (Ω · cm).
The seamless belt 1 was set as an intermediate transfer member of a color laser printer, and a printing test was performed on plain paper and an OHP sheet.
[0034]
Comparative Example The same carbon black as in Example 1 was mixed with dimethylacetamide to a concentration of 15% by weight, and the mixture was stirred and mixed by a ball mill for 8 hours to obtain a carbon black mixed solution. When the carbon black mixed solution was thus obtained, 25 parts by weight of the carbon black mixed solution was added to 100 parts by weight of the polyamideimide solution, and the mixture was stirred and mixed by a ball mill for 3 hours to obtain a polyamideimide-carbon black mixed solution. When the particle size distribution at this time was measured by a laser diffraction method, the ratio of particles having a particle size exceeding 150 nm was 32.2 wt%.
Next, using the same apparatus as in Example 1, a seamless belt 1 having a thickness of 100 μm was manufactured by the same method.
[0035]
Then, the surface resistivity and the volume resistivity of the outer peripheral surface 1a of the seamless belt 1 were calculated in the same manner as in Example 1, and 7.6 × 10 ¹² (Ω / □) and 2.2 × 10 ^{12 respectively.} (Ω · cm) was obtained.
The seamless belt 1 was mounted as an intermediate transfer member of a color laser printer, and a print test was performed on plain paper and an OHP sheet. As a result, good results were obtained with plain paper. However, in the case of the OHP sheet, color misregistration and rubbing, which are considered to be caused by the conveyance failure of the OHP sheet, were observed.
[0036]
【The invention's effect】
As described above, according to the present invention, it is possible to expect sufficient conductivity in the performance of toner conveyance and transfer, and to convey not only normally used paper but also OHP sheets and the like. This has the effect. Therefore, if this is used for a printer or the like, it becomes possible to widen the range of use of the substrate to be printed. Furthermore, since it is formed by centrifugal molding, it is possible to provide a seamless belt excellent in thickness accuracy, surface condition, and the like.
[Brief description of the drawings]
FIG. 1 is a perspective explanatory view showing an embodiment of a seamless belt according to the present invention.
FIG. 2 is an explanatory view showing a static mixer in the embodiment of the seamless belt according to the present invention, wherein FIG. 2 (a) is a front view, FIG. 2 (b) is a transverse sectional view, FIG. Fig. d) is a cross-sectional explanatory view showing a clamped state.
FIGS. 3A and 3B are explanatory diagrams showing electrodes for a resistivity test in the embodiment of the seamless belt according to the present invention, wherein FIG. 3A is an explanatory diagram showing a front electrode, and FIG. .
FIG. 4 is an explanatory diagram showing an insulation resistance measuring device for a resistivity test in the embodiment of the seamless belt according to the present invention.
5A and 5B are explanatory views showing a method of connecting electrodes in a resistivity test in an embodiment of the seamless belt according to the present invention, and FIG. 5A is a sectional explanatory view showing a method of connecting electrodes in a surface resistivity test; b) is a cross-sectional explanatory view showing a method of connecting electrodes during a volume resistivity test.
FIG. 6 is an explanatory view showing a mold in the embodiment of the seamless belt according to the present invention, wherein FIG. 6 (a) is a front view and FIG. 6 (b) is a side view.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Seamless belt 1a Outer surface 2 Static mixer 6 Insulation resistance measuring device 8 Mold

Claims (1)

A resin material solution in which a carbon filler is dispersed in a resin material is poured into a mold and rotated, and a seamless belt formed endlessly with a thickness of 0.02 to 0.5 mm by centrifugal molding,
The relationship between the surface resistivity ρs (Ω / □) and the volume resistivity ρv (Ω · cm) outside the peripheral surface is 109 ≧ ρs / ρv ≧ 40, and the surface resistivity ρs (Ω / □) is 2 × 10 A seamless belt characterized by being ¹³ (Ω / □) or more.

Images