JP4883697B2 - Method for producing semiconductive seamless belt - Google Patents

Description

  The present invention relates to a method for producing a seamless belt, and in particular, an electrophotographic copying machine equipped with an image forming apparatus, a printer, a facsimile, a transfer conveyance body, an intermediate transfer body, a transfer fixing body, etc. This is useful when manufacturing a semiconductive seamless belt used for a fixing body.

  In recent years, high speed and high image quality have been demanded for transfer conveyance belts, intermediate transfer belts, transfer fixing belts, and photosensitive belts used in image forming apparatuses such as electrophotographic copying machines, printers, facsimiles, and composite machines thereof. Therefore, seamlessness is desired for these functional belts. For this reason, for example, a seamless belt made of resin is produced by spreading a resin solution on the inner surface of a cylindrical mold, applying it to a certain thickness, and then heating the mold with hot air to evaporate the solution and drying it. Has been generally performed (see, for example, Patent Document 1). A method using induction heating to raise the temperature of the mold is known (see, for example, Patent Document 2).

  There are various image forming methods in the image forming apparatus. For example, as a method for transferring a visible image onto a transfer paper such as paper, a transfer drum method for winding a transfer paper such as paper on a transfer drum and transferring the visible image on the photosensitive member to the transfer paper for each color, An intermediate transfer body method is known in which a visible image on a photosensitive member is transferred to an intermediate transfer member for each color and then transferred to a transfer sheet at a time.

  In recent years, due to the trend of increasing the distance and image quality of image forming apparatuses and not selecting the type of paper, as a new image forming apparatus using an intermediate transfer member, a plurality of image carriers having developing units for each color Are arranged in series on the intermediate transfer body, and after transferring the visible image on the photoconductor to each color on the intermediate transfer body, the image is transferred to the transfer medium such as paper in a batch. The equipment is increasing.

Further, from the viewpoint of increasing the printing speed, the intermediate transfer belt is required to have a small difference between the left and right circumferential lengths.
JP 2002-225051 JP 2004-171831 A

  However, the seamless belt manufactured in Patent Document 1 warms the mold with hot air, and the hot air warming has poor thermal efficiency, and it takes a long time to heat the mold. On the other hand, as shown in Patent Document 2, when induction heating is used, it is possible to raise the temperature more rapidly than hot air, but the drawback is that the belt to be manufactured is easily repelled and the difference in circumferential length between the left and right belts becomes large. was there. In particular, it appeared remarkably when the ratio of the mold length to the mold diameter (mold length / mold diameter) was 3 or more.

  Therefore, an object of the present invention is to solve the above-described problems in the prior art and achieve the following object. That is, an object of the present invention is to provide a manufacturing method capable of manufacturing a semiconductive seamless belt having a small difference in peripheral length between left and right at a low cost in a short time.

In order to solve the above-mentioned problems, the present inventors have intensively studied in a method for producing a semiconductive seamless belt and have come to the following invention. That is, a seamless belt manufacturing method in which a resin solution, which is a raw material of a seamless belt, is applied to a cylindrical inner surface of a mold in a seamless manner, and then dried and cured to form a film.
The mold has a ratio of mold length to mold diameter (mold length / mold diameter) of 3 or more,
Supplying the resin solution to the inner surface of the mold;
A primary heating step of heating and drying the resin solution supplied in the supply step;
A secondary heating step of heating at a temperature higher than the primary heating step,
The primary heating step is characterized by heating using an induction heating method and blowing air at a wind speed of 2 m / sec or more on the inner surface of the mold.

The effects of this configuration are as follows. A resin solution, which is a raw material of the semiconductive seamless belt, is prepared (raw material weighing, mixing, storage). Next, supply (development and application) is performed on the inner surface of the hollow cylindrical mold so as to be seamless. Next, the resin solution is dried and cured using a drying means to form a film. A method for producing a semiconductive seamless belt comprising at least the above steps. In this manufacturing method, a mold having a ratio of the mold length to the mold diameter (mold length / mold diameter) of 3 or more is used. And in the case of drying by the primary heating using the induction heating method, it is configured to blow air at a wind speed of 2 m / second or more on the inner surface of the mold. As a result, it is possible to manufacture a semiconductive seamless belt with a small difference between the left and right circumferential lengths.

Further, as a preferred embodiment of the present invention is preferably carried out by induction heating method heating before Symbol secondary heating process. The advantage of the induction heating method is preferable because the mold can be heated (heated) rapidly and uniformly as compared with other heating methods (for example, hot air, far infrared device, etc.). In the present invention, air is blown at an air speed of 2 m / second or more on the inner surface of the mold. Therefore, the other heating methods obstruct heating, but the induction heating method is preferable because it does not obstruct.

  Hereinafter, the present invention will be described in detail.

(Raw material of semiconductive polyimide belt)
Polyimide resin, polyamideimide resin, polyetherimide resin, polyarylate resin, aromatic polyester resin, aromatic polyamide resin, etc. can be used as a raw material resin for seamless belts manufactured by the manufacturing method and manufacturing apparatus of the present invention. . Moreover, these can also be blended and used. In particular, when the seamless belt of the present invention is used as a transfer fixing body or a fixing belt, a heat resistant strength is required, and therefore a polyimide resin and a polyamideimide resin are preferable, and a thermosetting polyimide resin is more preferable. . As a raw material liquid for the polyimide resin, for example, a polyamic acid solution can be suitably used. This polyamic acid is obtained by reacting tetracarboxylic dianhydride or a derivative thereof and approximately equimolar amount of diamine in an organic solvent, and is usually used in the form of a solution, so that it is the main component of the resin solution used in the present invention. Can be used.

  Examples of tetracarboxylic dianhydrides include pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride Anhydride, 2,3,3 ′, 4-biphenyltetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride Products, 1,4,5,8-naphthalenetetracarboxylic dianhydride and the like.

  Examples of diamines include 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylmethane, 3,3′-diaminodiphenylmethane, 3,3′-dichlorobenzidine, 4,4′-diaminodiphenyl sulfide, 3 , 3′-diaminodiphenylsulfone, 1,5-diaminonaphthalene, m-phenylenediamine, p-phenylenediamine, 3,3′-dimethyl-4,4′-biphenyldiamine, benzidine, 3,3′-dimethylbenzidine, 3,3′-dimethoxybenzidine, 4,4′-diaminodiphenyl sulfone, 4,4′-diaminodiphenyl sulfide, 4,4′-diaminodiphenylpropane and the like can be mentioned.

  Examples of organic solvents include acetone, chloroform, methyl ethyl ketone, tetrahydrofuran, dioxane, acetonitrile, alcohols (methanol, ethanol, isopropanol, etc.), N, N-dimethylacetamide, dimethylformamide, N-methylpyrrolidone (NMP), etc. N, N-dimethylacetamide, NMP, and dimethylformamide, which are polar amide solvents, are preferable.

  When the seamless belt produced in the present invention is used as an intermediate transfer member or a transfer and conveyance belt, a high elastic modulus is required. Specifically, the circumferential tensile elasticity measured according to JIS-K7127. The rate is preferably 2000 MPa or more. Therefore, from this viewpoint, it is necessary to select the main component of the resin solution. For example, when polyamic acid is used as the main component of the resin solution, a solution containing 10% to 30% by weight of polyamic acid with respect to the total solution is used. Can be used in the resin solution of the present invention, a seamless belt preferable for an intermediate transfer member or the like can be produced.

Further, when the seamless belt produced in the present invention is used as an intermediate transfer member, a transfer carrier, or a transfer fixing member, it is necessary to add various conductive materials to the resin in order to obtain semiconductivity. Specifically, various polymers such as carbon, aluminum, nickel, tin oxide, and potassium titanate, and conductive polymers typified by polyaniline and polypyrrole can be used. In particular, it is important to uniformly disperse various conductive materials in order to make the entire belt uniform resistance and from the viewpoint of reducing the resistance of the belt. For this reason, when carbon black or the like is used, it is necessary to appropriately select a carbon black having good dispersibility and a dispersion method. The electric resistance value of the semiconductive seamless belt, when used as an intermediate transfer belt of an electrophotographic recording apparatus, it is preferable that the surface resistivity of ¹⁰ 8 ^{~10 14 Ω} / □ ^is, 10 10 ^{to 10 13} Omega More preferably, it is / □.

  In addition, when using a conductive polymer or the like, it is desirable to dissolve in the same solvent in which the resin material is dissolved.

  The content of these various conductive materials can be appropriately selected according to the type of the conductive material, but is preferably about 5 to 50% by weight, more preferably 7 to 40% by weight with respect to the resin. When the content is less than 5% by weight, the uniformity of electrical resistance is lowered, and the surface resistivity may be greatly lowered during durable use. On the other hand, if it exceeds 50% by weight, it is difficult to obtain a desired resistance value, and it becomes fragile as a molded product of a seamless belt, which is not preferable.

  The resin solution of the present invention preferably has a solution viscosity of 5 to 1000 Pa · s measured with a B-type viscometer. When the solution viscosity is 5 Pa · s or less, if a small amount of dust or foreign matter is mixed in the initial drying process, the solution resin will be repelled from that point, and the portion will become thin, resulting in a defective product. Conventionally, a method of slowing the drying rate has been adopted as a workaround, but this is not a preferable method because the manufacturing time becomes longer and the productivity is lowered. As another countermeasure, there is a method of installing a device for preventing the entry of dust and foreign matter, but this is not preferable because it leads to an increase in cost.

  On the other hand, when the solution viscosity is 1000 Pa · s or more, the resin is difficult to spread and it is difficult to form a uniform thickness, which is not preferable.

(Production method)
Below, the manufacturing method of a semiconductive seamless belt is demonstrated. The method for producing a seamless belt of the present invention mainly includes a step of preparing a solution-like resin solution as a raw material of the seamless belt, a step of spreading and applying the resin solution to the inner surface of the mold, a drying / curing step, an imidization It consists of the process of reacting.

  In the present invention, the resin solution is supplied (deployed / applied) to the inner surface of the cylindrical mold (first mold). This supply method can be performed by appropriately selecting a method using a dispenser, a method using a die, or the like. The resin solution supplied in this way can be appropriately selected, such as a method of centrifugal molding while heating, a method of molding using a bullet-shaped traveling body, a method of rotational molding, etc. good.

  Next, in the previous step, the resin solution uniformly applied to the inner surface of the first mold is heated. First, primary heating (corresponding to initial drying) is performed until self-supporting is possible. At this time, the airflow flowing on the inner surface of the first mold needs to be at a wind speed of 2 m / sec or more. When the airflow flowing on the inner surface of the first mold is less than 2 m / sec, not only is the belt repelled but also the difference in the circumferential length between the left and right is not preferable. The temperature / humidity conditions of the blast are set by the resin solution, but in order to perform drying appropriately, the temperature is preferably 25 ° C. or higher and the humidity is preferably 50% or lower. A well-known thing can be suitably employ | adopted for an air blower.

  The primary heating temperature is not particularly limited as long as it is a temperature at which the applied solvent can be evaporated, and can be appropriately set, but is preferably 80 to 230 ° C. The heating time is appropriately set according to the heating temperature, and is usually about 10 to 60 minutes. At this time, if heated rapidly at 230 ° C., the solvent in the resin solution rapidly evaporates, so microvoids are generated. If heated for less than 80 ° C. for a long time, it takes too much production time and productivity is lowered, which is not preferable. .

  Next, secondary heating is performed to remove residual solvent, ring-opening water, or imidization reaction. The temperature of the secondary heating is not particularly limited as long as it is a temperature suitable for this purpose, but usually 250 ° C. to 400 ° C. is preferable. The heating time is appropriately set according to the heating temperature, and is usually about 10 to 60 minutes.

  A seamless belt peeled off from the first mold after the primary heating is inserted outside the cylindrical second mold used to regulate the inner diameter of the seamless belt, and tertiary heating is performed in this inserted state. It is also possible.

As a heating method and a heating device for primary heating or secondary heating, it is desirable to raise the temperature of the first mold by using an induction heating method and an induction heating device that can rapidly increase the temperature and have low energy cost. When the induction heating apparatus is used, the first mold is preferably made of a magnetic material such as iron.

  Next, the seamless belt applied to the inner surface of the first mold and cured to form a film is peeled off. As this peeling method, for example, a method of pressure-feeding air to a minute through-hole provided in advance on the peripheral wall of the end of the mold can be used. In addition, it is preferable to perform a release treatment with a silicone resin or the like in advance on the inner surface of the mold because the workability of peeling the seamless belt is improved.

The semiconductive seamless belt obtained by the above production method is free from defects such as repelling and has a small difference in peripheral length between the left and right sides. Therefore, even if this semiconductive seamless belt is used as an intermediate transfer belt for a color printer or the like, it is very good without color unevenness.
[Example]

  Hereinafter, the present invention will be described more specifically with reference to examples. However, these examples do not limit the present invention.

(Evaluation methods)
(1) Surface resistance (overall) evaluation: Hiresta UPMCP-H1450 (manufactured by Mitsubishi Chemical Co., Ltd., probe UR) is used as a measuring instrument, and voltage is 100 V at any 24 points on the surface of the semiconductive seamless belt under measurement conditions of 25 ° C. The surface resistance value 10 seconds after the start of application was measured. Here, the average value of the measured 24 points was defined as the surface resistance.
(2) Inner circumference difference evaluation: As shown in FIG. 1, the belt was stretched by applying a load of 4 kg on two parallel shafts (diameter 30 mm). The distance between the parallel axes at that time was measured on the left and right sides (distance between axes: A (right), A (left)). The left and right inner circumferences were calculated by the following formula (1).
(Formula 1) Inner circumference = 30 * 3.14 + 30 + 2 × A
The difference between the obtained inner circumference lengths on the left and right was taken as the inner circumference length difference.

Example 1
Carbon black (SPECIAL BLACK4, manufactured by Degussa) was added to N-methyl-2-pyrrolidone (NMP) and stirred for 8 hours with a ball mill to obtain a carbon black-dispersed NMP liquid. 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and equimolar number of 4,4′-diaminodiphenyl nitrile are dissolved in this carbon black-dispersed NMP solution, and the mixture is stirred at room temperature for 5 hours under a nitrogen atmosphere. After reacting with stirring, the viscosity was adjusted to obtain a polyamic acid solution (solid content 20 wt%, solution viscosity 300 B · s at 23 ° C. using a B-type viscometer) in which carbon black was dispersed. While pushing out 420 g of this polyamic acid solution from an annular die (outer diameter 250 mm, length 500 mm) to form a hollow resin solution, this hollow resin solution was removed from the inner surface of the cylindrical mold (ratio of mold length to mold diameter). 3.3 (inner diameter 300 mm, length 1000 mm)). Next, primary heating was performed using an induction heating device, and air blowing at a wind speed of 8 m / sec (temperature 25 ° C., humidity 50% or less) was performed on the inner surface of the mold. In the primary heating, heating was performed at 130 ° C. for 20 minutes using an induction heating device. Next, in order to remove the residual solvent, remove the decyclized water, and complete the imidization reaction, the temperature was raised to 360 ° C. at a rate of 40 ° C./min using an induction heating apparatus, Until cooled. Unnecessary portions at both ends of the obtained belt and two central portions were cut to obtain three semiconductive seamless belts. This belt was good without cissing.

(Comparative Example 1)
A semiconductive seamless belt was produced in the same manner as in Example 1 except that the air velocity to the inner surface of the mold was changed to 1 m / sec.

(result)
As is clear from Table 1, Example 1 has a smaller circumferential length difference and no occurrence of repelling compared to Comparative Example 1. Further, the surface resistance value of Example 1 is a value suitable for an intermediate transfer belt, for example, but Comparative Example 1 is inappropriate as an intermediate transfer belt.

  The semiconductive seamless belt obtained in the above examples is free from defects such as repelling and has a small difference in peripheral length between the left and right. Therefore, even if this semiconductive seamless belt is used as an intermediate transfer belt for a color printer or the like, it is very good without color unevenness.

Diagram explaining the inner circumference measurement method

Claims (5)

A seamless belt manufacturing method in which a resin solution, which is a raw material of a seamless belt, is applied seamlessly to a cylindrical inner surface of a mold, and then dried and cured to form a film,
The mold has a ratio of mold length to mold diameter (mold length / mold diameter) of 3 or more,
Supplying the resin solution to the inner surface of the mold;
A primary heating step of heating and drying the resin solution supplied in the supply step;
A secondary heating step of heating at a temperature higher than the primary heating step,
A method for producing a seamless belt, wherein the primary heating step heats using an induction heating method and blows air at an air speed of 2 m / sec or more on the inner surface of the mold.   The method of manufacturing a seamless belt according to claim 1, wherein the heating in the secondary heating step is performed by an induction heating method.   The method for producing a seamless belt according to claim 1 or 2, wherein a heating temperature in the primary heating step is 80C to 230C.   The method for producing a seamless belt according to any one of claims 1 to 3, wherein a heating temperature in the secondary heating step is 250C to 400C.   The method for producing a seamless belt according to claim 1, wherein the resin solution supplied to the inner surface of the mold has a viscosity measured by a B-type viscometer of 5 to 1000 Pa · s.

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