KR20080056564A - Intermediate transfer belt and manufacturing method thereof - Google Patents

Abstract

An intermediate transfer belt and a manufacturing method thereof are provided to reduce surface resistance difference between inner and outer peripheral surfaces of the belt, using a polyamide acid liquid, so as to improve the driving performance of the belt and to maintain the specific thickness of the belt. A manufacturing method of a polyamide intermediate transfer belt comprises the steps of; coating a polyamide acid liquid(4) on an outer peripheral surface of a mold(3), using rollers(1,2); and heat-treating the coated polyamide acid liquid for polyimide. The rollers are more than two. The polyamide acid liquid includes 0.5 to 35 weight% of an electric conductive filer. The heat treatment is carried out at 50 to 400 degrees.

Description

Intermediate transfer belt and manufacturing method

1 is a perspective view schematically showing an example of the intermediate transfer belt manufacturing method of the present invention.

* Description of the main symbols in the drawings

1: first roller 2: 2nd roller

3: mold 4: polyamic acid solution

The present invention relates to an intermediate transfer belt and a method of manufacturing the same used in a laser printer, a facsimile machine, a copier, and the like.

In general, in order to be used as intermediate transfer belt of laser printer, facsimile machine and copier, it should be excellent in heat dissipation property, water repellency, oil repellency, pollution resistance, heat resistance, elastic modulus, release property with paper, antistatic property, durability and antistatic property. .

The polyimide compound has many advantages such as excellent thermal stability, mechanical and electrical properties, so it is being studied as an intermediate transfer belt. It is very sensitive to moisture, so the reliability of electrical insulation decreases with time. In addition, due to high glass transition temperature, there are many restrictions on processing, and it is relatively easy to be charged.

Intermediate transfer belts are required to have proper volume resistivity to transfer toners. If they are lower or higher than the required volume resistivity, their antistatic properties, transfer properties, image properties, mold release properties and contamination resistance are required. Deterioration of properties such as performance can lead to fatal defects of burn defects.

On the other hand, if the surface resistance difference between the inner circumferential surface and the outer circumferential surface of the intermediate transfer belt is large, it is difficult to control the resistance of the area required for the intermediate transfer belt, and it also affects the volume resistance depending on which part of the intermediate transfer belt. In the related art, in order to reduce the difference in surface resistance, there is a hassle of having to adjust the surface resistance to each other by applying an antistatic coating on the inner circumferential surface or the outer circumferential surface or by polishing.

Even if the antistatic coating is applied separately, the manufacturing method becomes cumbersome and the manufacturing cost increases, and in the product, the separation of the layer between the antistatic coating layer and the original belt and the absorption of the coating layer adversely affect the quality of the image when the image is realized. Can be crazy

In addition, the intermediate transfer belt such as a laser printer, a facsimile machine, and a copy machine plays a role in transferring the toner, so it must be manufactured to be seamless.

In order to make the intermediate transfer belt seamlessly, there is a method of applying a polyamic acid solution to the inner circumferential surface or the outer circumferential surface of the mold by using a dispenser, which is limited to apply uniformly on all sides, and can be used when the viscosity of the solution is high. When the polyamic acid solution was applied to the outer circumferential surface of the mold using a dispenser, and heat was applied from the outside, the solvent was impossible to evaporate, and thus the defect was high.

In addition, in order to make the intermediate transfer belt seamlessly, the laundry container method of high speed rotation using centrifugal molding is used. This method can be used when the viscosity is low, and when the rotation axis is inclined, the intermediate transfer belt can be manufactured. No, there is a limit to the high-speed rotation by rotating the rotary shaft straight, there was a disadvantage that some thickness deviation occurs.

Accordingly, an object of the present invention is to provide an intermediate transfer belt and a method for manufacturing the same, which improve the driving characteristics of the belt due to the small difference in surface resistance between the inner and outer peripheral surfaces while using the polyimide compound.

It is also an object of the present invention to provide an intermediate transfer belt having a constant thickness and a method of manufacturing the same without a seam.

The present invention for achieving the above object provides a polyimide-based intermediate transfer belt having a surface resistance variation of the outer circumferential surface and a surface resistance variation of the inner circumferential surface of 10 ^-2 to 10 ² without undergoing a separate surface treatment process.

The intermediate transfer belt has a thickness variation of 7% or less, a volume resistivity of 10 ⁵ to 10 ¹² Ωcm, and modulus of elasticity (Modulus) of 3.0 to 7.0 GPa.

In addition, the present invention comprises the steps of applying a polyamic acid solution to the mold outer peripheral surface using a roller; And it provides a method for producing a polyimide-based intermediate transfer belt comprising the step of imidizing the applied polyamic acid solution.

It is characterized by using two or more rollers.

The polyamic acid solution is characterized in that it comprises 0.5 to 20% by weight of the electrically conductive filler based on the total solute.

Heat treatment in the step of imidizing is characterized in that carried out at 60 ~ 450 ℃.

Hereinafter, the present invention will be described in more detail.

The polyimide resin for the intermediate transfer belt of the present invention is prepared by dissolving dianhydride, diamine, and an electrically conductive filler in a solvent to prepare a polyamic acid solution, and then applying the same to a mold outer surface using a roller and then heat-treating the imidization. It is obtained by.

In the intermediate transfer belt of the present invention, it is preferable that the surface resistance of the outer circumferential surface and the surface resistance fluctuation of the inner circumferential surface of the intermediate transfer belt measured after the surface treatment such as antistatic coating is not formed are 10 ⁻² to 10 ² . The change in surface resistance can be calculated from the surface resistance value of the outer circumferential surface and the surface resistance value of the inner circumferential surface. When the surface resistance variation exceeds 10 ² , it is difficult to control the resistance of the required area of the intermediate transfer belt. Because of this effect, the operation becomes difficult during image realization, and when the surface resistance fluctuation value is less than 10 ⁻² , low resistance is formed on the outer circumferential surface when voltage is applied, so that development fillers such as toner are not well fixed.

The diamine component for preparing the polyimide resin is not particularly limited as long as the diamine component is used in the production of polyimide resin, oxydianiline (4,4'-Oxydianiline, ODA), p-phenylenediamine (para- phenylene diamine (pPDA), m-phenylene diamine (mPDA), p-methylenediamine (para-Methylene Diamine, pMDA), m-methylenediamine (mMDA) and the like can be used. .

On the other hand, dianhydride is not particularly limited as long as it is used in the production of polyimide resin, pyromellitic acid dianhydride (1,2,4,5-benzene tetracarboxylic dianhydride, pyromellictic acid dianhydride (PMDA), benzophenone tetra Carboxylic dianhydrides (3,3,4,4-Benzophenonetetracarboxylic dianhydride (BTDA), biphenyl tetracarboxylic dianhydrides (3,3,4,4-Biphenyltetracarboxylic dianhydride, BPDA), oxydiphthalic dianhydride Ride (4,4-Oxydiphthalic dianhydride) and the like can be used.

Diamine and dianhydride for preparing the polyimide resin are used in equimolar amounts.

The solvent may be selected from aprotic superpolar solvents such as N, N-dimethylformamide (DMF), dimethylacetamide (DMAc) and N-methylpyrrolidinone (NMP).

Meanwhile, an electrically conductive filler capable of adjusting the volume resistance value of the intermediate transfer belt to be manufactured is included in the preparation of the polyamic acid solution. Examples of the electrically conductive filler include ketjen black, acetylene black, furnace black, metals such as aluminum and nickel, metal oxides such as tin oxide, and metal oxides such as tin oxide and potassium titanate. It is preferable to obtain the electrical conductivity required to use 0.5 to 35% by weight of the sole powder or one or more selected from conductive polymers such as polyaniline or polyacetylene with respect to the total solute. . In addition to this may further include a metal filler, it is good to use 0.1 to 5% by weight based on the total solute.

The method of dispersing the electrically conductive filler is not particularly limited, and typically, an ultrasonic disperser capable of efficient dispersing is preferably used.

Dispersion stabilizer used in the present invention is a polymeric dispersant, the kind of poly-N-vinyl formamide, poly-N-vinyl aceteamide, poly- Dispersants such as N-vinylpyrrolidone (poly-N-vinyl pyrolidone), poly-N-vinyl caprolactam (poly-N-vinyl caprolactam) and the like may be used, the dispersant may be used differently depending on the type of dispersion.

The reaction temperature for preparing the polyamic acid solution for producing the polyimide-based resin is preferably 0 to 60 ° C, and the reaction time is preferably 0.5 to 12 hours.

A polyimide intermediate transfer belt is obtained by applying the prepared polyamic acid solution to the mold outer circumferential surface using a roller, followed by heat treatment to imidize it.

In the present invention, two or more rollers are used, which will be described in more detail with reference to the accompanying drawings.

1 is a perspective view schematically showing an example of the intermediate transfer belt manufacturing method of the present invention.

In the present invention, the intermediate transfer belt is manufactured by applying the polyamic acid solution 4 to the outer peripheral surface of the mold 3 using the rollers 1 and 2, followed by heat treatment to imidize it.

The rollers 1, 2 are located in parallel with the mold 3, and the two rollers 1, 2 and the mold 3 mesh with each other to rotate.

That is, for example, when the first roller 1 rotates clockwise, the second roller 2 rotates counterclockwise, and the mold 3 rotates clockwise. At this time, the first roller 1 is in contact with the polyamic acid solution 4, while the polyamic acid solution 4 is applied to the first roller 1 while the first roller 1 is rotated, the applied solution ( 4) is applied successively to the second roller 2 which rotates in contact with the first roller 1. The solution 4 is then applied to the outer circumferential surface of the mold 3 which rotates in contact with the second roller 2. In this way, the polyamic acid solution 4 is applied to the mold 3 through the plurality of rollers 1 and 2 so that the coating amount and the coating thickness of the polyamic acid solution 4 are adjusted. The coating thickness of the polyamic acid solution (4) is preferably 40 to 200㎛ when heat-treated in the mold (3) to produce an intermediate transfer belt, the thickness deviation is preferably 7% or less. When the thickness variation exceeds 7%, the thickness variation of the film is deepened after the polyamic acid solution 4 is imidized, and the developability of the intermediate transfer belt is lowered.

At this time, if the rollers 1 and 2 and the mold 3 are not parallel to each other, the distance between the first roller 1 and the second roller 2 and the second roller 2 and the mold 3 is wide. It is important to maintain parallelism because the solution 4 is concentrated to a place, which causes a serious imbalance in the coating thickness and causes a problem of not rotating properly with each other.

In addition, when the rotation speed and the rotation time of each of the rollers 1 and 2 and the mold 3 are not adjusted, the polyamic acid solution 4 is concentrated between the first roller 1 and the second roller 2. It may not be applied to the mold (3), the thickness deviation is increased, so care must be taken in the adjustment of the rotation speed and rotation time. In consideration of this point, the rotational speeds of the rollers 1 and 2 and the mold 3 are preferably 50 to 200 rpm, and the rotation time is 1 to 4 hours.

Alumina, stainless steel, Teflon and the like can be used as the mold 3, and the size is not particularly limited, but is preferably 200 to 300 mm in length and 100 to 150 mm in inner diameter.

The polyamic acid solution 4 may be heat-treated stepwise in the applied mold 3 and then detached from the mold 3 to prepare a polyimide intermediate transfer belt. Stepwise heat treatment can be performed in an IR heater, an electric furnace or a hot air oven, and pre-baking is performed at a temperature range of 50 to 100 ° C. to remove solvent and water remaining on the surface of the belt. . After performing the above pretreatment, the temperature rising rate of 2 ~ 10 ℃ per minute to maintain the final post-curing (350-400 ℃) to completely remove the solvent and water remaining on the surface and inside of the intermediate transfer belt It is preferable to proceed with the imidation to complete the imidization and to produce a solidified film. If necessary, after prebaking, the belt may be detached from the mold, turned over, and then post-cured by inserting the mold into a small mold.

When manufacturing the intermediate transfer belt by the manufacturing method as described above, the thickness deviation can be reduced by minimizing the rotation of the mold (3) to adjust the thickness of the intermediate transfer belt, the surface between the outer peripheral surface and the inner peripheral surface of the manufactured intermediate transfer belt The resistance difference can be reduced.

That is, after forming the polyamic acid solution 4 applied to the mold 3, the surface resistance of the outer circumferential surface and the surface resistance variation of the inner circumferential surface are 10 ^-2 to 10 ² without surface treatment such as antistatic coating. It is satisfied that the thickness variation is 7% or less, so that the intermediate transfer belt exhibiting excellent insulation and developability can be manufactured.

Although the present invention has been described with reference to the accompanying drawings, the present invention is not limited thereto, and a person skilled in the art may change the present invention without departing from the technical spirit of the present invention. Do.

The manufactured intermediate transfer belts have a volume resistance value in the range of 10 ⁵ to 10 ¹² Ωcm, which is inherently intermediate resistance value, and thus semi-conductive type laser printer, facsimile and radiation with improved antistatic property, antistatic property and printability, etc. The intermediate transfer belt can be manufactured.

In addition, the transfer belt of the present invention has an elastic modulus of 3.0 to 7.0 GPa, preferably 3.2 to 5.0 GPa. If the elastic modulus is low, mechanical deformation is feared when used for a long time as an intermediate transfer belt. If the elastic modulus is high, it is difficult to mold.

Hereinafter, examples of the present invention will be described in more detail, but the scope of the present invention is not limited to these examples.

<Example 1>

While nitrogen was introduced into a four-necked flask equipped with a mechanical stirrer, a reflux cooler, and a nitrogen inlet, 3.36 g of ketjen black was added to DMF 1007 g and dispersed in an ultrasonic disperser, where 118 g of BPDA and 80 g of ODA were added thereto. Reaction to prepare a polyamic acid solution containing a conductive filler. The viscosity of this solution was 1950 poise at 23 degreeC.

After applying the polyamic acid solution to the outer peripheral surface of the cylindrical molding mold in the same manner as in Figure 1 and then pre-baking (pre-baking) at a temperature of 80 ℃ to first remove the solvent and water remaining on the belt surface, per minute By maintaining a temperature increase rate of 5 ℃ to finally post-curing up to 350 ℃ to prepare a polyimide intermediate transfer belt containing a seamless conductive filler is completely removed from the solvent and water remaining on the surface and inside At this time, the thickness of the manufactured belt was 65 micrometers.

<Example 2>

After the polyamic acid solution was prepared in the same manner as in Example 1, the solution was applied to the mold in the same manner, and after prebaking, the belt was detached from the mold and flipped over to mount the belt on a mold having an inner diameter of 4% smaller than the mold used. Next, after curing, a polyimide-based intermediate transfer belt was manufactured, and the thickness of the prepared belt was 63 μm.

Comparative Example 1

While nitrogen was introduced into a four-necked flask equipped with a mechanical stirrer, a reflux cooler, and a nitrogen inlet, 3.36 g of ketjen black was added to DMF 1007 g and dispersed in an ultrasonic disperser, where 118 g of BPDA and 80 g of ODA were added thereto. Reaction to prepare a polyamic acid solution containing a conductive filler. The viscosity of this solution was 1840 poise at 24 degreeC.

Thereafter, the polyamic acid solution was coated on the inner circumferential surface of a cylindrical cylinder having an inner diameter of 120 mm and a length of 250 mm, rotated at 1200 rpm for 20 minutes, and the solvent was removed under the same conditions as in Example 1, and then hardened to prepare a polyimide intermediate transfer belt. One belt was 71 mu m thick.

Comparative Example 2

After preparing a polyamic acid solution in the same manner as in Comparative Example 1, the polyamic acid solution was put into a cylindrical Teflon mold composed of a double structure of an outer cylinder and an inner cylinder and prebaked at a temperature of 80 ° C to remain on the belt surface. After the solvent and water were first removed, the inner cylinder was separated from the outer cylinder.

Thereafter, a temperature increase rate of 5 ° C. per minute was maintained, followed by final curing to 350 ° C., thereby preparing a polyimide-based intermediate transfer belt. The thickness of the belt was 68 μm.

Physical properties of the intermediate transfer belts prepared in Examples and Comparative Examples were evaluated by the following methods, and the results are shown in Table 1 below.

(1) Surface resistance variation

Using a resistance meter (HIRESTA UP) manufactured by Mitsubishi Chemical, voltage was continuously applied to the sample and measured. At this time, the voltage applied to the sample was 100V. In addition, in order to measure the surface resistance, a sample was installed on a substrate made of fluorine-based polymer having excellent insulation, and the inner and outer peripheral surfaces of the sample were separated and measured at intervals of 10 seconds on the corresponding surface. In this case, a ring-shaped probe was used. It was. The size of the sample used for measuring the surface resistance was 20 × 20 cm, and the measurement was performed 10 times per surface to obtain an average value. And the variation value was computed with the following formula.

Surface resistance fluctuation value = | Surface resistance value of outer peripheral surface / Surface resistance value of inner peripheral surface |

(2) Volume resistance value

Using a resistance meter (HIRESTA UP) manufactured by Mitsubishi Chemical, voltage was continuously applied to the sample and measured. At this time, the voltage applied to the sample was 100V. In addition, in order to measure the volume resistance, a sample was installed on a substrate of a metal material and measured at intervals of 10 seconds for each sample. In this case, a ring-shaped probe was used. The size of the sample used for the volume resistivity measurement was 20 × 20 cm, and the measurement was performed 10 times to obtain an average value.

(3) Modulus

Measurement was performed according to ASTM D882 using Instron's Universal Testing Machine Model 1000.

(4) thickness and thickness deviation

The thickness of the sample was measured by using a micrometer (Anritus, Electronic micrometer) after drying the sample at 100 ° C. for 1 hour. The thickness of the sample was measured 50 times and the average value was obtained after removing the largest and smallest values. Thickness variation was expressed in% through the formula for calculating the general thickness variation.

(5) developability

The intermediate transfer belts prepared in Examples and Comparative Examples were applied to the transfer unit to implement the same image after connection to a color laser printer, and were classified according to the number of defects in the state of the developed paper. It is very good if the number of defects is less than 10 by developing 1000 times, good if more than 10 times and less than 30 times, good if more than 30 times and less than 50 times, bad if more than 30 times and less than 50 times, bad if more than 50 times, less than 100 times. Evaluated.

Surface resistance change Volume resistance (Ωcm) Modulus of elasticity (GPa) Thickness (㎛) Thickness deviation (%) Developability Example 1 4.23 1.75 × 10 ⁹ 3.65 65 3.5 Very good Example 2 2.17 1.62 × 10 ⁹ 3.7 63 3.5 Very good Comparative Example 1 253.3 2.73 × 10 ⁹ 3.5 71 7.9 Good Comparative Example 2 1527.3 2.55 × 10 ⁹ 3.41 68 9.2 usually

As a result of the measurement of the physical properties, the intermediate transfer belt of the embodiment manufactured by the manufacturing method of the present invention showed that the surface resistance variation of the outer circumferential surface and the inner circumferential surface was 4.23 and 2.17, respectively, and there was almost no difference in the surface resistance of the outer circumferential surface and the inner circumferential surface, and the thickness deviation was 7 The intermediate transfer belt having a relatively constant thickness of less than% can be produced, showing very good developability.

On the other hand, the intermediate transfer belt of the comparative example had a large surface resistance difference between the inner circumferential surface and the outer circumferential surface as the surface resistance resistance value of the outer circumferential surface and the inner circumferential surface was 10 ² or more, and the thickness deviation exceeded 7%.

As described above, the present invention manufactures an intermediate transfer belt and an intermediate transfer belt which improve the driving characteristics of the belt by reducing the difference in the surface resistance between the inner and outer circumferential surfaces even when the polyimide compound is not treated with subsequent antistatic coating. It may provide a method.

In addition, the present invention can provide an intermediate transfer belt having a constant thickness and a method of manufacturing the same by minimizing the thickness deviation without a seam.

Claims (8)

The polyimide intermediate transfer belt of the polyimide intermediate transfer belt which has not undergone a separate surface treatment process, wherein the surface resistance of the outer circumferential surface and the surface resistance variation of the inner circumferential surface of the polyimide intermediate transfer belt calculated by the following equation are 10 ^-2 to 10 ² . Surface resistance fluctuation value = | Surface resistance value of outer peripheral surface / Surface resistance value of inner peripheral surface | The method of claim 1, Polyimide intermediate transfer belt, characterized in that the thickness deviation is 7% or less. The method of claim 1, Polyimide intermediate transfer belt, characterized in that the volume resistance value is 10 ⁵ ~ 10 ¹² Ωcm. The method of claim 1, Modulus (Modulus) is a polyimide-based intermediate transfer belt, characterized in that 3.0 to 7.0 GPa. Applying a polyamic acid solution to the mold outer peripheral surface using a roller; And Method of producing a polyimide-based intermediate transfer belt comprising the step of imidating the applied polyamic acid solution. The method of claim 5, wherein Method for producing a polyimide intermediate transfer belt, characterized in that using two or more rollers. The method of claim 5, wherein The polyamic acid solution is a method for producing a polyimide intermediate transfer belt, characterized in that it comprises 0.5 to 35% by weight of an electrically conductive filler based on the total solute. The method of claim 5, wherein Heat treatment in the step of imidating is a method for producing a polyimide intermediate transfer belt, characterized in that carried out at 50 ~ 400 ℃.

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