JP2001129837A - Semiconductive belt and production method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductive belt enhanced in productivity and improved in a problem of appearance such as warpage or surface cracking while putting the merit of a double-layered belt good in the uniformity of mechanical characteristics or an electric resistance value to practical use and useful as an intermediate transfer belt or a transfer feed belt and a method for producing the same. SOLUTION: In a method having a process performing the coating of a plurality of raw material solutions containing polyamic acid, the removal of a solvent from a coating film and the imide conversion of polyamic acid and producing a semiconductive belt having a plurality of polyamide resin layers at least one of which contains a conductive substance, a plurality of the raw material solutions are almost uniformly applied in succession or at the same time and the solvent is removed from the respective layers at the same time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductive belt having a plurality of polyimide resin layers containing a conductive substance in at least one layer and a method for producing the same, and particularly useful as an intermediate transfer belt and a transfer belt. It is something.

[0002]

2. Description of the Related Art Conventionally, copiers, laser printers, video printers, facsimile machines, multifunction machines thereof and the like have been known as electrophotographic recording apparatuses for forming and recording images by electrophotography. In this type of apparatus, in order to improve the life of the apparatus, an image formed by a recording material such as toner on an image carrier such as a photosensitive drum is directly fixed on a printing sheet by an image forming method. An intermediate transfer method for temporarily transferring an image on a carrier to an intermediate transfer belt and fixing the image on a print sheet has been studied. Further, for the purpose of downsizing the apparatus, a method of performing transfer while transporting a print sheet by a transport belt has been studied.

As a semiconductive belt which can be used for such an intermediate transfer belt and a transfer conveyance belt, for example, Japanese Patent Application Laid-Open No.
JP-63115-A proposes an intermediate transfer belt in which a conductive material is dispersed in a polyimide resin having excellent mechanical properties. However, since this intermediate transfer belt is mainly composed of a single layer type, it has been difficult to uniformly disperse the conductive material in relation to the thickness determined by the balance of strength and the like. For this reason, the dispersion state of the conductive material is not sufficient, and the variation in the electric resistance value (particularly, surface resistivity ρs) of the belt becomes large, which is not satisfactory in practical use. Therefore, when used as an intermediate transfer belt or a transfer conveyance belt of a copying machine, a laser printer, or the like, transfer unevenness occurs in a toner image transferred to a print sheet, or when a print sheet being conveyed is separated from the belt. However, there is a problem that a separation failure occurs.

To solve such a problem, Japanese Patent Application Laid-Open No.
In 156287, a polyimide-based resin is mainly used, and by providing a plurality of layers having different surface resistivity,
There is disclosed a semiconductive belt in which variation in electric resistance value and reduction in mechanical strength are improved. The method for producing this belt is to apply a polyamic acid solution as a raw material liquid for the first layer to the inner surface of the cylindrical shape, remove the solvent to a certain extent under temperature conditions such that imide conversion is not performed, and solidify the solution. After applying the raw material liquid of the second layer to the inner surface of the first layer, drying the solvent, and simultaneously performing imide conversion of both layers.

[0005]

However, when a multi-layer belt is manufactured by the above-described method, there is a drawback that productivity is not good because the solvent must be dried for each layer. In addition, since two layers having a large difference in the residual amount of the solvent must be dried at the same time, the belt tends to be warped due to a difference in residual stress, and in extreme cases, a problem such as cracking of the belt surface occurs. Occurs. Furthermore,
When the raw material liquid of the second layer is applied, since the solvent concentration is low on the surface of the first layer, mutual diffusion of the resin component does not easily occur at the interface between both layers, and sufficient strength cannot be obtained at the interface after imide conversion. There is.

Accordingly, an object of the present invention is to improve the productivity while taking advantage of the advantages of a multi-layer belt having good uniformity of mechanical properties and electric resistance values, and to improve the appearance of the belt such as warpage of the belt and cracks on the surface. It is an object of the present invention to provide a semiconductive belt useful as an intermediate transfer belt or a transfer conveyance belt, and a method for manufacturing the same.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies on a method of manufacturing a semiconductive belt in order to achieve the above object. The inventors have found that the above object can be achieved by simultaneously removing the solvent in each layer before the amount of transfer of the acidic substance increases, and have completed the present invention.

That is, the method for producing a semiconductive belt according to the present invention comprises the steps of applying a plurality of raw material solutions containing polyamic acid, removing a solvent from the coating film, and performing imide conversion of the polyamic acid. In a method of manufacturing a semiconductive belt having a plurality of polyimide-based resin layers containing a conductive substance in at least one layer, the plurality of raw material liquids are applied almost uniformly all at once or simultaneously, and then a solvent is simultaneously applied to each layer. It is characterized by being removed.

In the above, all of the raw material liquids are B
Solution viscosity at 25 ° C. in a viscometer is 10 to 10,000
It is preferably within the range of poise.

On the other hand, the semiconductive belt of the present invention is a semiconductive belt obtained by the manufacturing method of the present invention, and is a seamless semiconductive belt having a boundary surface in a cross section caused by a difference in the content of a conductive substance. It is a conductive belt.

Further, the semiconductive belt of the present invention is a semiconductive belt having a plurality of polyimide resin layers containing a conductive substance in at least one layer. This is a seamless semiconductive belt having a boundary surface caused by the cross section and peeling off at a portion other than the boundary surface when forcible peeling is performed.

[Effects] According to the production method of the present invention,
Since the plurality of raw material liquids are all applied almost uniformly, the solvent is simultaneously removed from each layer, so that it is not necessary to perform solvent drying for each layer, thereby simplifying the process and shortening the time, and improving the productivity. . Also, when drying multiple layers simultaneously,
Since there is almost no difference in the residual amount of the solvent, a difference in the residual stress hardly occurs, and a problem due to the difference hardly occurs. Further, when a plurality of raw material liquids are applied, mutual diffusion of the resin easily occurs at the interface between the plurality of layers, so that sufficient strength is easily obtained at the interface after imide conversion. As a result, while utilizing the advantages of a multilayer belt with good uniformity of mechanical properties and electric resistance values, an intermediate transfer belt with improved productivity and improved appearance problems such as belt warpage and surface cracks have been developed. A semiconductive belt useful as a transfer conveyance belt can be provided.

When the raw material liquid has a solution viscosity at 25 ° C. in a B-type viscometer within a range of 10 to 10,000 poise, mixing between layers due to transfer of a conductive substance at an interface of each layer is difficult to occur. The function of each layer can be more reliably expressed. Further, when the solution viscosity is within the above range, it becomes easy to apply each layer without causing disturbance at the interface between the layers.

On the other hand, since the semiconductive belt of the present invention can be obtained by the manufacturing method of the present invention, the appearance problems such as warpage of the belt and cracks on the surface are improved. Further, since the cross section has a boundary surface caused by the difference in the content of the conductive substance, the function of each layer can be effectively exhibited.

Another semiconductive belt according to the present invention has a boundary surface in a cross section caused by a difference in the content of the conductive substance, and peels off at a portion other than the boundary surface when forcible peeling is performed. As a result, the functions of the respective layers can be effectively exhibited in the same manner as described above, and the durability in long-term use is excellent.

[0016]

Embodiments of the present invention will be described below. The production method of the present invention includes a step of applying a plurality of raw material liquids containing polyamic acid, removing a solvent from a coating film, and performing an imide conversion of the polyamic acid. Are sequentially or simultaneously applied substantially uniformly, and then the solvent is simultaneously removed from each layer.

The semiconductive belt to be manufactured may be an endless belt or the like having a seam, but when used as an intermediate transfer belt or a transfer conveyance belt, a seamless belt without a seam is preferable. The seamless belt can be formed by a centrifugal molding method using a cylindrical mold, a coating method of running a pig or the like in the cylindrical mold, a method using an outer cylindrical mold and a cylindrical inner mold, and the like. However, in consideration of the uniformity of the belt size and belt thickness described later, the centrifugal molding method is particularly preferable. Hereinafter, the centrifugal molding method will be described in detail as an example. However, all of these methods are known, and the present invention can be carried out according to the case of the centrifugal molding method.

When a semiconductive belt having two layers, an inner layer and an outer layer, is manufactured by a centrifugal molding method, for example, first, a raw material liquid for an outer layer containing a polyamic acid solution is supplied to an inner peripheral surface of a cylindrical mold, and a cylindrical liquid is supplied. The film is formed (coated) to a uniform thickness by rotating the shape and centrifugal force. Next, the inner layer raw material solution containing the polyamic acid solution is supplied onto the inner surface of the formed outer layer, and the inner layer is formed by rotating the cylindrical mold. After removing the solvent by heating and drying the outer and inner layers at 80 to 160 ° C., the mixture is further heated to 300 to 450 ° C. to promote imidization (ring-closing imidization reaction) and release from the cylindrical mold. Thus, a seamless belt is obtained. At that time, by including a conductive material in at least one layer of the raw material liquid, a semiconductive belt having a plurality of polyimide resin layers containing the conductive material in at least one layer can be manufactured.

It is also possible to simultaneously supply two layers of the raw material liquid into a cylindrical shape to form a film. In this case, the supply nozzle may have a two-layer structure. Further, a semiconductive belt having three or more layers can be formed. In this case, the raw material liquids corresponding to the three or more layers may be applied sequentially or simultaneously in the same manner as described above.

In the present invention, it is important to apply a plurality of raw material liquids to each layer as uniformly as possible, and to remove the solvent before the amount of transfer of the conductive substance between the layers increases. In order to uniformly apply the raw material liquid to each layer, it is important to apply the upper raw material liquid without disturbing the surface of the lower coating film.This involves adjusting the viscosity of the raw liquid and applying it to the lower layer surface. When the upper layer raw material liquid is applied, it can be achieved by equalizing the mold temperature, suppressing the variation in viscosity, and equalizing the coating film. Further, in order to prevent the transfer amount of the conductive substance from increasing between the layers, it is effective to adjust the viscosity of the raw material liquid.

That is, the viscosity of the raw material liquid is preferably from 10 to 10,000 poise at 25 ° C. in a B-type viscometer,
00-7000 poise is more preferred. When it is less than 10 poise, when the inner layer is supplied to the outer layer after film formation and the film is formed by centrifugation, the outer and inner layers tend to mix. Also,
If it exceeds 10,000 poise, it becomes difficult to form a film by centrifugal force, it is difficult to make the thickness uniform, and this has an adverse effect on the appearance and characteristics of the belt.

A polyamic acid solution as a raw material liquid for a polyimide resin can be obtained as follows. For example, a polyamic acid obtained by polymerizing tetracarboxylic dianhydride or its derivative (a) and diamine (b) in a solvent such as N-methyl-2-pyrrolidone can be used. At this time, the monomer concentration (the concentration of (a) + (b) in the solvent) is set according to various conditions, but is preferably 5 to 30% by weight. Further, the reaction temperature is preferably set to 80 ° C. or lower, particularly preferably 5 to 50 ° C. By reacting the acid dianhydride with the diamine in this manner, a polyamic acid is generated, and the viscosity of the solution increases with the reaction. Thereafter, the viscosity at 25 ° C. of the polyamic acid solution in a B-type viscometer can be adjusted to 10 to 10,000 poise by utilizing the phenomenon that the viscosity is reduced by heating and stirring. The heating temperature at that time is preferably 80 ° C. or less. Adjustment by the monomer concentration is also possible. In addition, as a raw material compound such as a tetracarboxylic dianhydride or a derivative thereof, or a diamine, any of known compounds used for a semiconductive belt can be used.

The conductive substance to be added to impart semiconductivity to the polyimide resin layer is preferably a conductive or semiconductive substance, such as carbon black such as Ketjen black and acetylene black, Al and Ni. Metals, metal oxide compounds such as tin oxide, potassium titanate and the like can be used. The compounding of the conductive substance can be carried out by previously dispersing in a solvent or dispersing in a polyamic acid solution.

Semi-conductivity can be imparted by appropriately selecting the above-mentioned conductive substance and performing the treatment in an appropriate amount. When used as an intermediate transfer belt, it is preferable that the outer layer has a surface resistivity ρs of 10 ⁵ to 10 ¹⁵ Ω / □ and the inner layer has a surface resistivity ρs of 10 ¹¹ Ω / □ or more and is adjusted to a higher value than the outer layer. This is because in order to increase the overall strength of the belt, it is preferable that the content of the conductive material in the inner layer is small, and more preferable that the conductive material is not contained.

The size of the semiconductive belt is appropriately set according to the application. For example, when the semiconductive belt is used for an intermediate transfer belt or a transfer conveyance belt, the thickness is preferably 10 to 300 μm, particularly preferably 20 to 200 μm. .

The semiconductive belt of the present invention is a semiconductive belt obtained by the above-described manufacturing method, and is a seamless semiconductive belt having a cross section at a boundary surface caused by a difference in the content of a conductive substance. It is a sex belt. The semiconductive belt obtained by the manufacturing method, when applying a plurality of raw material liquids, because the mutual diffusion of the resin easily occurs at the interface of the plurality of layers,
It is easy to obtain sufficient strength at the interface after imide conversion. As a result, a semiconductive belt having a plurality of polyimide-based resin layers containing a conductive substance in at least one layer, having a boundary surface in a cross section caused by a difference in the content of the conductive substance in a cross section, and A seamless semiconductive belt in which peeling occurs at a portion other than the boundary surface when a temporary peeling is performed.

Such a semiconductive belt can improve productivity because the solvent drying step can be performed once while utilizing the advantages of a layered belt having good uniformity of mechanical properties and electric resistance values. It is useful as an intermediate transfer belt or a transfer conveyance belt in which problems such as belt warpage and surface cracks in appearance are improved.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments and the like specifically showing the configuration and effects of the present invention will be described below.

Example 1 A dispersion obtained by mixing 29.3 g of carbon black (Vulcan XC manufactured by Cabot Corporation) in 1566.6 g of N-methyl-2-pyrrolidone in a ball mill at room temperature for 6 hours was added to 3,3 ′, 294.0 g of 4,4'-biphenyltetracarboxylic dianhydride and p-phenylenediamine 10
8.0 g was dissolved therein, and the mixture was stirred and reacted at room temperature.
After the viscosity was increased, the mixture was stirred for 10 hours while heating to 50 ° C. to obtain a carbon-dispersed polyamic acid solution of 600 poise at 25 ° C.

Similarly, N-methyl-2-pyrrolidone 1
296.6 g of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and 108.0 g of p-phenylenediamine were dissolved in 566.6 g, and the mixture was stirred and reacted at room temperature. After increasing the viscosity, heat to 50 ° C
The mixture was stirred for 25 hours to obtain a polyamic acid solution of 500 poise at 25 ° C.

The above-mentioned carbon-dispersed polyamic acid solution was applied to the inner surface of a mold having an inner diameter of 180 mm and a length of 500 mm via a dispenser, and was rotated at 1500 rpm for 10 minutes to obtain a uniform spread layer having a thickness of 200 μm.

Next, a polyamic acid solution was applied to the above inner surface in the same manner.
And then apply 250 rpm in a drying oven at 150 ° C.
The solvent was dried for 30 minutes while rotating the mold at m.
Further, the temperature was raised to 350 ° C. at a rate of 2 ° C./min,
The mixture was heated at a temperature for 30 minutes to allow the imide conversion to proceed. room temperature
After being cooled, it is peeled off from the mold, and the outer layer has a surface resistance of 1 × 10 ¹²
(Μm / semiconductor) with a total thickness of 75 μm having a semiconductive layer
An electrically conductive belt was obtained.

When the cross section of the belt was observed with an optical microscope, it was confirmed that a boundary surface caused by a difference in carbon content (presence / absence) was present at the boundary between the outer layer and the inner layer. When the external appearance of the belt was confirmed, no warpage or cracks on the belt surface were found. Furthermore, when the belt was forcibly peeled off, peeling was likely to occur at a portion other than the boundary surface between the two layers.

Example 2 A 5500 poise carbon-dispersed polyamic acid solution obtained by the same operation as in Example 1 except that the reaction temperature was set to normal temperature, the viscosity was increased, and the mixture was stirred for 5 hours while heating to 40 ° C. Example 1 using a polyamic acid solution of 4800 poise
Surface resistance 2 × 10 ¹² (Ω / □) in outer layer by the same operation as
A semiconductive belt having a total thickness of 74 μm and a semiconductive belt having the following semiconductive layer was obtained.

Observation of the cross section and surface of the belt and forced peeling were performed in the same manner as in Example 1. As a result, good results were obtained as in Example 1.

Comparative Example 1 A 12,000 poise carbon-dispersed polyamic acid solution obtained in the same manner as in Example 1 except that the reaction temperature was set to room temperature, the viscosity was increased, and the mixture was stirred at room temperature for 5 hours, was placed on the inner surface of a mold.
It was applied through a dispenser and rotated at 1500 rpm for 10 minutes, but a uniform spread layer was not obtained.

Reference Example 1 A dispersion obtained by mixing 1831.3 g of N-methyl-2-pyrrolidone with 29.3 g of dried carbon black (Vulcan XC manufactured by Cabot Corporation) in a ball mill at room temperature for 6 hours was added to 3,3 ', 4. , 4'-biphenyltetracarboxylic dianhydride 294.0 g and p-phenylenediamine 108.0
g was dissolved and reacted at room temperature with stirring. After the viscosity increased, the mixture was stirred for 10 hours while heating to 70 ° C. to obtain a carbon-dispersed polyamic acid solution of 5 poise at 25 ° C.

Similarly, N-methyl-2-pyrrolidone 1
293.0 g of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and 108.0 g of p-phenylenediamine were dissolved in 831.3 g, and the mixture was stirred and reacted at room temperature. After the viscosity rises, it is heated to 70 ° C.
Stirring was performed for an hour to obtain a polyamic acid solution of 3 poise at 25 ° C.

When the same operation as in Example 1 was performed using the above solution, a belt of 68 μm was obtained. Example 1
In the same manner as above, the cross-section and surface of the belt were observed, and the forcible peeling was performed. , No boundary between the outer and inner layers
Carbon was present throughout the belt.

Comparative Example 2 A 5-poise carbon-dispersed polyamide solution prepared in the same manner as in Reference Example 1 was applied to the inner surface of a mold via a dispenser, and rotated at 1500 rpm for 10 minutes to obtain a uniform spread layer. After obtaining a uniform spread layer of 200 μm,
30 while rotating the mold at 250 rpm in a drying oven.
Separate solvent drying was performed.

A 3 poise polyamic acid solution prepared in the same manner as in Comparative Example 2 was applied in the same manner to the inner surface of the dried and cured outer layer, dried and then heated to 350 ° C. at a rate of 2 ° C./min. The mixture was heated at a temperature for 30 minutes to allow the imide conversion to proceed. After cooling to room temperature, it was peeled off from the mold to obtain a semiconductive belt having a total thickness of 68 μm and having a semiconductive layer having a surface resistance of 1 × 10 ¹² (Ω / □) as an outer layer.

When the appearance of the belt was confirmed, the belt was greatly warped and cracks were found on the belt surface. Further, when the belt was forcibly peeled off, interfacial peeling was likely to occur at the interface between the two layers.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Toshiaki Iwamoto 1-1-2 Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation (72) Inventor Hiroshi Matsuo 1-1-1-2 Shimohozumi, Ibaraki-shi, Osaka F-term in Nitto Denko Corporation (reference) 2H032 BA09 BA18 4F205 AA40 AB18 AC05 AE03 AG03 AG08 AG16 AR17 GA02 GB01 GB26 GC04 GE03 GF01 GF02 GF23 GF24 GN02 GN17 GN22 GN29 4F213 AA40 AB18 AC05 AE03 AG03 WA08 AR16 WC03 WE03 WE06 WF01 WF02 WF23 WF24 WK03

Claims (4)

[Claims] 1. A method for applying a plurality of raw material liquids containing a polyamic acid, removing a solvent from a coating film, and performing imide conversion of a polyamic acid, wherein at least one layer contains a conductive material. In a method of manufacturing a semiconductive belt having a polyimide-based resin layer, after applying the plurality of raw material liquids sequentially or simultaneously substantially uniformly all at once, the solvent is removed simultaneously for each layer of the semiconductive belt Production method. 2. The method for producing a semiconductive belt according to claim 1, wherein each of the raw material liquids has a solution viscosity at 25 ° C. in a B-type viscometer within a range of 10 to 10,000 poise. 3. A seamless semiconductive belt obtained by the production method according to claim 1, wherein the seamless semiconductive belt has a boundary surface in a cross section caused by a difference in the content of a conductive substance. 4. A semiconductive belt having a plurality of polyimide-based resin layers containing a conductive substance in at least one layer, wherein a cross-sectional surface resulting from a difference in the content of the conductive substance is provided in a cross section. A seamless semiconductive belt in which peeling occurs at a portion other than the boundary surface when forcible peeling is performed.