JPH0266009A - Conveyance belt and conveyance method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a conveyor belt used in a transfer-type electrostatic recording device such as an electrophotographic device, particularly a transfer belt therein, and a transfer/conveyor belt using the same. Regarding the method.

(Prior Art) Conventionally, as a transfer belt used in an electrophotographic device, a dielectric film such as polyethylene terephthalate is spliced together into a belt shape by means such as thermal welding or ultrasonic welding, and an inner layer of the dielectric film is used. aluminum, gold,
Vapor-deposited conductive materials such as tin oxide and carbon, N
It is known that conductive rubber such as BR, SBR, or EPDM is used, and the above-mentioned film is wound thereon.

Also, as an endless belt, for example, JP-A-62-15
As shown in No. 6682, the volume resistivity is 10'4
It is disclosed that a thermoplastic resin layer having an ΩcI of 11 or more and a thermoplastic elastomer or ionomer having a volume resistivity of 106 ΩcIw or less are provided in the inner layer thereof, and both layers are integrally formed into an endless belt by extrusion blow molding.

Furthermore, in JP-A No. 62-203169, thermoplastic elastomer or ionomer has a volume resistivity of IO+2.
Also disclosed is an endless belt having a surface dielectric layer with a surface dielectric layer having a resistivity of ~1016 Ωcm and a semiconductive thermoplastic elastomer or ionomer having a volume resistivity of 10'~1012 Ωcm in its inner layer, in which both layers are integrally extruded and blow molded. ing.

(Problems to be Solved by the Invention) However, the above-mentioned conventional example has the following problems.For example, in a system in which a dielectric film such as polyethylene terephthalate is heat-welded or ultrasonically welded, the transfer belt may be damaged due to the step at the joint. The toner adhering to the surface of the transfer material accumulates there and cannot be cleaned completely, causing stains on the back of the transfer material.
Furthermore, the strength of the joints is weak, which poses a problem in durability.

Furthermore, in the case of an insulating dielectric film, it is difficult to stabilize the potential on the dielectric surface, and when the transferred material is peeled off from the electrostatic mfgl carrier, the dielectric Charges of opposite polarity to the transfer electric field accumulate on the surface of the body film, causing a so-called charge-up phenomenon, which may result in poor adsorption of the transferred material and poor transfer of the toner image.

On the other hand, the structure in which a conductive layer is provided on the back side of the dielectric film is
JP-A-56-154772, JP-A-62-15036
As shown in No. 2, etc., in the one-layer method, in which the conductive layer is used as a reference potential surface and the surface layer is always kept constant by contact charging, corona charging, etc., a dielectric film is used. The problem at the joint is the same as in the conventional example, but the charge-up phenomenon is less likely to occur. However, since the transfer belt has a conductive layer on its back surface, the electric field on the surface of the transfer belt is uniform, so the toner on the electrostatic latent image carrier moves toward the electrostatic latent image carrier before the image carrier and the transfer belt come into contact. The electric field in the attracting direction causes the toner to fly in the direction of the transfer belt, making it impossible to faithfully transfer the toner image, resulting in so-called ``Tobichiri'' (a state in which toner particles are lost around the character area). In order to prevent this phenomenon, the electric field on the surface of the transfer belt is weakened. It has the disadvantage of causing

JP-A No. 62-156682 discloses an endless belt having a conductive layer as an inner layer, but since the belt is endless, problems such as unevenness at joints can be solved, but having a conductive layer as an inner layer On the other hand, in the endless transfer belt disclosed in JP-A No. 62-203169, the dielectric layer on the surface layer is 1012 to 10
It is a thermoplastic elastomer or ionomer with a resistance of ΩcII+, and the dielectric layer retains an electric charge for a certain period of time (about several seconds or less) and quickly (about several seconds).
The charge is attenuated (characteristics are shown). However, in order to obtain such characteristics, the relationship between the resistance and capacitance of the dielectric layer is severely limited.
It is difficult to stably obtain a volume resistivity of I, and it is susceptible to variations due to material manufacturing conditions and environmental changes, making it practically difficult to obtain the effects disclosed in this publication.

Furthermore, this publication uses a method of charging the transfer belt surface and stabilizing the transfer belt surface at a constant potential before the transfer belt moves toward the transfer section, as in the conventional example, so that " Problems such as "hollowing" cannot be solved, and since both the surface layer and the inner layer are made of thermoplastic elastomer layers in this publication, wear, deformation, elongation, etc. due to long-term durability of the elastomer layer become a problem. In severe cases, there is also the problem that the transfer belt breaks during the durability test.

The purpose of the present invention is to eliminate the drawbacks of the above-mentioned conventional examples, to enable stable adsorption of the transfer material with little environmental fluctuation, to obtain high transfer efficiency, and to faithfully transfer the toner image on the electrostatic latent image carrier. It is an object of the present invention to provide a conveyance belt, especially a transfer belt, which is capable of transferring images to obtain high image quality, and a transfer/conveyance method using the same.

Furthermore, another object of the present invention is to provide a transfer belt having excellent surface smoothness, excellent cleaning properties for toner adhering to the transfer belt, and characteristics that can withstand long-term use, and a transfer/conveying method using the transfer belt. It is about providing.

[Means to solve the problem]

The present invention has a first layer made of synthetic resin and a thermoplastic elastomer, and has a volume resistivity of 10' to 1014 ΩC.
A conveyor belt having a second layer of l11,
Preferably, the first layer is a resin layer selected from polyethylene terephthalate, fluororesin, polyethylene, polyamide, polyimide, polycarbonate, and polysulfone, and the high-resistance layer is a polyolefin-based thermoplastic elastomer, polyester-based thermoplastic elastomer, or polyurethane-based resin layer. Thermoplastic elastomer, fluorine-based thermoplastic elastomer, polystyrene-based thermoplastic elastomer, polyamide-based thermoplastic elastomer, polyptadiene-based thermoplastic elastomer, polyethylene-based thermoplastic elastomer, ethylene-vinyl acetate-based thermoplastic elastomer, polyvinyl chloride-based thermoplastic elastomer This is an endless conveyor belt characterized by a thermoplastic elastomer layer selected from.

FIG. 1 is a diagram showing the layer structure of the transfer belt 1.
An insulating layer 31 and an adhesive layer 32 made of synthetic resin as layers of
, the volume resistivity as the second layer is 10&~lQ+4Ω
It has a three-layer structure including a high resistance layer 33 of cm. Second
The figure shows a conceptual diagram of an endless belt.

The insulating layer 31 is made of polyethylene terephthalate, tetrafluoroethylene/hexafluoropropylene (FEP), tetrafluoroethylene/propylene hexafluoride (FEP),
Volume resistivity is 10 with resin layers such as perfluoroalkoxyethylene (pFA), polyvinylidene fluoride, polyimide, polyamide, polycarbonate, and polysulfone.
The thickness is 14 Ωcm or more and the thickness is between lθ and 150 μl,
Preferably, the width is between 20 and 70 μm.

The high resistance layer 33 is made of polyolefin thermoplastic elastomer, polyester thermoplastic elastomer, polyurethane thermoplastic elastomer, polystyrene thermoplastic elastomer, polyamide thermoplastic elastomer, fluorine thermoplastic elastomer, polyptadiene thermoplastic elastomer, polyethylene thermoplastic elastomer. , an ethylene-vinyl acetate thermoplastic elastomer, a polyvinyl chloride thermoplastic elastomer, etc., and the elastomer contains carbon black, a conductive filler such as metal powder, and a titanium compound.

Used are elastomers mixed with semiconductive fillers such as nickel compounds and silicon compounds, and elastomers made of high resistance by changing the structure of the polymer, and the volume resistivity of the elastomer layer at this time is 10' to 10'. 1014
Controlled between Ωcm, thickness 50-300μ
It is said to be between l.

The adhesive layer 32 can be appropriately selected depending on the materials of the high resistance layer and the insulating layer. At this time, it is desirable that the volume resistivity of the adhesive layer 32 is higher than that of the high resistance layer.

In the present invention, using the above materials, an endless belt is manufactured by extruding each layer or centrifugally molding, etc., and then an adhesive is applied to bond the insulating layer and the high resistance layer.
It becomes possible to select an appropriate method depending on the material used, such as the simultaneous and integral molding method by extrusion blow molding disclosed in Japanese Patent No. 2-156682.

At this time, by using a thermoplastic elastomer with good moldability as the inner high-resistance layer, it is possible to
It becomes possible to form an endless belt having a thickness of approximately 1.0 mm, and it becomes possible to obtain an endless belt having an optimum wall thickness as a transfer belt at a relatively low cost.

FIG. 3 is a schematic cross-sectional view of a transfer/conveyance device using the belt of the present invention. The toner image formed on the photosensitive drum II, which is an electrostatic latent image carrier, is transferred to the photosensitive drum 11 with the belt 1 in between.
The image is transferred onto the transfer material P by the action of the transfer charger 12 provided at a position opposite to the transfer material P. Thereafter, the transfer material P is electrostatically attracted to the belt 1 and is stably conveyed. The belt 1 is driven by a first roller 14 or a second roller 16 and rotates at the same speed as the photosensitive drum 11.

Here, the 10th wire 14 and the 20th wire 16 have conductivity and are each grounded. Toner adhering to the belt 1 is cleaned by a cleaner 15.

At this time, it is preferable to provide a blade as the cleaner, and rubber such as urethane, chloroprene, NBR, etc. can be used. On the belt 1, charges with a polarity opposite to that for transfer are accumulated on the belt surface due to air discharge when the transfer material P is separated from the photosensitive drum 11 and when the transfer material P is separated from the belt 1. A static eliminator 13 is provided for removing static electricity. A DC voltage or an AC voltage having a polarity opposite to that of the transfer charge is applied to the static eliminator.

[Example] As the transfer belt 1, a polyethylene terephthalate resin is extruded into a tube shape, and further stretched with two wheels to obtain a tube of desired dimensions. In this example, the diameter is 80 mm and the width is 23 mm.
The dimensions were 0 mm and a thickness of 30 μm. Furthermore, polyolefin-based thermoplastic elastomer was extruded in the same way, and the diameter was 79.4 mm, the width was 230 [1111 mm], and the thickness was 100 mm.
A μl tube was obtained. At this time, carbon black is mixed in the elastomer in an amount of 5 to 30 L% to obtain a desired resistance value. The polyethylene terephthalate tube and elastomer tube obtained in this way are stacked together,
Heald 1 was obtained by bonding with an adhesive. Here, the thickness of the adhesive layer was 20 μm, and the total thickness of the transfer belt 1 was 150 μm.

Using the transfer belt thus obtained, the resistance of the inner elastomer layer was changed by varying the amount of carbon black dispersed, and the transfer results were obtained when 10 sheets were successively passed through the transfer/conveying device shown in Figure 3. The change in efficiency is shown below. At this time,
Paper feeding speed is 100mad/sec, photosensitive drum 1
1 is an organic photoconductor sensitized to the long wavelength side (hereinafter referred to as OP
The experiment was conducted using a reversal development method in which a latent image is formed using a semiconductor laser (not shown) and the exposed area is developed with a single component negative polarity magnetic toner. Plus a transfer charger! 2, corona discharge was performed under constant current control of 200 μA, and the static eliminator 13 was caused to perform corona discharge under constant current control of 150 μ^. Table 1 shows the experimental results at this time.

Table 1 From this experimental result, a practically sufficient value of transfer efficiency was determined to be 7.
If it is 5% or more, and a more preferable value is 80% or more, the volume resistivity value required for the elastomer layer is 108~
It can be seen that 1QI4ΩC1m. The reason for this is that if the resistance is too low, the charge for transfer will leak through the elastomer layer and a sufficiently strong transfer electric field will not exist, and if the resistance is too high, a charge-up phenomenon will occur. It is thought that the transfer efficiency gradually decreases.

On the other hand, since the elastomer layer is a high-resistance layer, its thickness affects the capacitance of the belt 1. If it is too thick, the capacitance will be small, making it impossible to strengthen the transfer electric field, which will affect the transfer efficiency. It will affect you. Table 2 shows the results of measuring the transfer efficiency by changing the thickness of the nilastor layer under the same conditions as in the above experimental example, with the volume resistivity value of the elastomer layer, which is a high resistance layer, being 1011ΩCll1.

Table 2 From this experimental result, the practical thickness of the elastomer layer is 300 mm.
It needs to be 1 m or less, preferably 200 μl or less. By the way, elastomers are generally elastic bodies and have weaker permanent deformation, tensile strength, abrasion resistance, etc. than resins. Therefore, when used as a transfer belt, sufficient durability cannot be obtained with the elastomer layer alone, and in particular, a thickness of 300 μI or more is required to obtain sufficient strength properties and endure the passing of 300,000 sheets or more. It becomes necessary. On the other hand, as in the present invention, the surface has excellent properties such as abrasion resistance, tensile strength, and permanent deformation, and especially has a tensile strength of 150 kg/cm.
By having a resin layer of m2 or more, preferably 300 kg/cm2 or more on the surface layer, sufficient durability can be obtained even if the elastomer layer is thin. Furthermore, the thinner the resin layer on the surface, the better the transfer efficiency, but if it is extremely thin, the durability will be poor for the same reason as mentioned above.

According to the inventor's study, the surface resin layer has a thickness of 10 to 1
A thickness between 00 μm, more preferably between 20 and 70 μl is excellent in terms of transfer efficiency and durability. In addition, cleaning properties require surface smoothness, and resin layers that meet the above characteristics include polyethylene terephthalate, tetrafluoroethylene resin, tetrafluoroethylene/hexafluoropropylene resin, and tetrafluoroethylene/peroxide resin. Examples include fluororesins such as fluoroalkoxyethylene resin and polyvinylidene fluoride resin, polyethylene, polyamide, polyimide, polycarbonate, polysulfone, and more preferably polyethylene terephthalate, polyamide, polyimide, polycarbonate, polysulfone, and the like.

FIG. 4 is a schematic cross-sectional view of a transfer/conveyance device for carrying out the present invention. The toner image formed on the photosensitive drum 11 is transferred by the electric field of the transfer roller 42 onto the transfer material P which has been electrostatically attracted onto the belt 1 by the attraction roller 44 in advance. The toner on the belt 1 is cleaned by a cleaner 15, and the charge having the opposite polarity to the transfer electric field present on the belt 1 is eliminated by a grounded static elimination brush 45. At this time, a constant voltage of 0.5 to 3 kV having a polarity opposite to that of the toner is applied to the transfer roller 42 by a power source 43.

Further, a voltage of 0.2 to 1.5 kV with the same polarity as that of the toner is applied to the suction roller 44 by the power source 46, and a charge is injected onto the transfer material. The transferred material P is strongly electrostatically attracted onto the belt 1 by the electrostatic force of the charges induced by the layer. As a result, the transfer material P can be transported against gravity.

More specifically, the transfer roller 42 has a volume resistivity of 106 Ωcm or less and a hardness of 20 to 50 degrees (JIS
A) EPDM, CR, NBR, conductive rubber such as silicone rubber, or hardness 15-40 (ASKERC)
Use a conductive sponge made of urethane, silicone, etc.

Similarly, the suction roller 44 uses a conductive rubber roller such as EPDM, CRlNBR, or silicone rubber to improve the adhesion of the transfer material to the belt 1.

In the configuration of this embodiment, the electrostatic attraction force of the transfer material P to the belt 1 needs to be sufficiently strong. According to the inventor's study, the electrostatic adsorption force between the transfer material P and the belt 1 depends on the resistance and smoothness of the surface layer of the belt 1, and in particular, the resistance value of the surface layer affects the charge retention ability of the belt 1. In other words, it affects the suction force when the resistance of paper, which is the transfer material, becomes low under high temperature and high humidity conditions (for example, 35° C. and 85%).

In this example, the same belt as in the previous example was used, but the diameter of the belt was 150III11. In addition, experiments were conducted to control the resistance value by dispersing and mixing a surfactant or a conductive filler such as carbon black into the polyethylene terephthalate layer used as the surface insulating layer.
Table 3 shows the evaluation of the adsorption power to. At this time, the paper feeding speed was 30 mm/sec, and other image forming conditions were the same as in the previous example. The material to be transferred was paper with a basis weight of 58 g/m2 that had been left at 35° C. and 85% for 2 days, a voltage of -500 V was applied to the suction roller 44, and a voltage of +1.5 kV was applied to the transfer roller 42. The experiment was conducted by applying .

Table 3 Here, in the adsorption force evaluation, ○ indicates that the transferred material is completely P until the time of separation.
△ indicates a state in which the transferred material P is slightly separated from the belt 1 near the separation part, and X indicates a state where the transferred material P is separated from the photosensitive drum It immediately after the transferred material P is separated from the belt 1. This shows a state in which the belt is separated from the belt 1. The belt surface potential half-life time is the result of charging the belt surface to a constant potential and then measuring the time course of the surface potential using a surface potentiometer.

In order to obtain sufficient adsorption force between the transferred material and the belt even under high temperature and high humidity conditions, the resistance of the belt surface layer must be IQ + 4Ωc.
It can be seen that the resistance is required to be ot or more, preferably 1015 Ωcm or more. This is considered to be to prevent the adsorption charges applied to the paper from leaking from the surface layer of the paper and the transfer belt, which have become low in resistance. Further, in the case of having a charge supply member (in this embodiment, the suction roller 44) in contact with the belt 1 as in this embodiment, if there is a pinhole or the like in the insulating layer on the belt surface, voltage will leak from there. Therefore, it is desirable that the surface layer of the belt 1 be an insulating layer without pinholes. Furthermore, even when a filler with low electrical resistance is mixed into the surface insulating layer, a similar phenomenon is likely to occur, so it is desirable not to mix filler into the surface insulating layer.

Insulating layers that have a resistance value that satisfies the above characteristics and are less likely to have pinholes include polyethylene terephthalate, tetrafluoroethylene/perfluoroalkoxyethylene, tetrafluoroethylene/hexafluoropropylene, polyvinylidene fluoride, Resin layers such as polyethylene, polyamide, polyimide, polycarbonate, polysulfone, etc. can be suitably used.

Further, in this configuration, sufficiently excellent transfer efficiency, image quality, etc. can be obtained for the same reasons as in the above embodiments.

〔Effect of the invention〕

As explained above, the surface layer of the belt is formed of a resin layer, and the inner layer of the resin layer has a volume resistivity of 10' to 1Q14.
By forming a high-resistance layer of Ωcl11 and making the high-resistance layer from a thermoplastic elastomer, the charge in the high-resistance layer can be easily removed, making it difficult to cause a charge-up phenomenon. Since the toner image can be concentrated, it is possible to achieve high transfer efficiency, faithfully transfer the toner image on the electrostatic latent image carrier, and obtain high image quality.

Furthermore, since the surface layer has a resin layer that is strong and has excellent abrasion resistance, permanent deformation, and smoothness, a belt that can pass paper for a long period of time can be obtained. Furthermore, since the surface resin layer is strong, the overall thickness of the belt can be made sufficiently thin.
A sufficiently strong transfer electric field can be obtained with respect to the image carrier, making it easier to obtain high transfer efficiency.

Furthermore, an elastomer with good extrusion moldability can be used as the inner high-resistance layer, and the diameter and thickness of the belt can be freely selected. Furthermore, since the mechanical properties of the transfer belt itself are controlled by the surface resin layer, there is greater freedom in selecting the elastomer material used for the inner elastomer layer, and the material has excellent filler dispersibility when controlling resistance. Even in the range of 10 8 to 10 Ωcm, which is difficult to control, a desired resistance value can be obtained with relatively good grain size, resulting in excellent productivity.

In addition, by setting the resistance of the resin layer on the surface of the belt to 1014 ΩcI11 or more to provide sufficient charge retention, it is possible to obtain sufficient electrostatic adhesion force to moisture-absorbing paper even under high temperature and high humidity conditions. Even if contact charging is applied to the surface layer, there is no risk of leakage because there are no pinholes or other areas where the withstand voltage is locally weak.

In this specification, the case where the belt is used as a transfer belt has been described, but the present invention can be applied to belts for conveying other paper, film, and the like.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the layer structure of a belt according to the present invention, FIG. 2 is a schematic sectional view of a transfer belt according to the present invention, and FIGS. 3 and 4 are schematic diagrams of a transfer/conveying device equipped with a belt according to the present invention. FIG. 1: Belt 11: Photosensitive drum 12: Transfer charger 13: Static eliminator + 4.16: Roller 15: Cleaner 31: Insulating layer 32: Adhesive layer 33: High resistance layer 42: Transfer roller 43: Power source 44: Adsorption roller 45 : Static elimination brush 46: Power supply b kA3 Figure 2 Figure 4

Claims (1)

[Claims] 1) The first layer is made of synthetic resin and thermoplastic elastomer, and has a volume resistivity of 10^8 to 10^1^4 Ωc.
A conveyor belt having a second layer of m. 2) Claim 1 in which the first layer is made of polyethylene terephthalate, fluororesin, polyethylene, polyamide, polyimide, polycarbonate, or polysulfone.
Belt as described in. 3) The belt according to claim 1 or 2, wherein the first layer has a volume resistivity of 10^1^4 Ωcm or more. 4) The second layer is a polyolefin thermoplastic elastomer, polyester thermoplastic elastomer, polyurethane thermoplastic elastomer, polystyrene thermoplastic elastomer, polyamide thermoplastic elastomer, fluorine thermoplastic elastomer, polyptadiene thermoplastic elastomer, polyethylene 4. The belt according to claim 1, wherein the belt is a thermoplastic elastomer layer selected from a thermoplastic elastomer, an ethylene-vinyl acetate thermoplastic elastomer, and a polyvinyl chloride thermoplastic elastomer. 5) The belt according to any one of claims 1 to 4, which is endless. 6) The belt and/or the material to be transferred according to any one of claims 1 to 5 is charged, the material to be transferred is attracted to the belt by electrostatic force, and the material to be transferred is moved by moving the belt. Conveyance method to be transported.