KR20090095812A - Intermediate transfer belt and manufacturing method thereof - Google Patents

Abstract

An intermediate transfer belt is provided to uniformly transfer a toner by lowering surface roughness through preventing the formation of protrusions on the surface. A method for manufacturing a polyimide-based intermediate transfer belt comprises the steps of: preparing a polyamic acid solution; applying the polyamic acid solution to the outer circumference of a mold; rotating the mold applied with the polyamic acid solution at the speed of 50~200rpm; and performing imidation by heat-treating the coated polyamic acid solution.

Description

Intermediate transfer belt and manufacturing method

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 belts such as laser printers, facsimile machines, and copiers, heat dissipation properties, water repellency, oil repellency, fouling resistance, heat resistance, elastic modulus, release property with paper, antistatic properties, durability, and antistatic properties should be excellent.

In particular, the intermediate transfer belt is required to have an appropriate volume resistivity for transferring the toner, and when it is lower or higher than the required volume resistivity, their antistatic properties, transfer properties, image characteristics, releasability and resistance This is because physical properties such as contamination may be deteriorated, which may result in a fatal defect of burn defects.

Recently, the intermediate transfer belt uses a polyimide compound which has many advantages such as excellent thermal stability, mechanical and electrical properties, and is very sensitive to moisture, and thus the reliability of electrical insulation decreases with time. Due to the glass transition temperature, there are many restrictions on processing, and there is a problem of relatively easy charging.

In order to overcome this problem, even if the antistatic coating is performed 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 are performed when the image is implemented. Can adversely affect quality.

Therefore, when preparing the intermediate transfer belt, a filler is added to a polyimide precursor to supplement these electrical properties and imidized to manufacture the intermediate transfer belt.

However, since the intermediate transfer belt, which serves to transfer the toner, should be seamless, it uses a laundry box method of high speed rotation by centrifugal molding. This method can be used when the viscosity of the polyamic acid solution, a polyimide precursor, is low. Since the density of the injected filler is different from that of PI Varnish, the phenomena caused by the centrifugal force cause the phenomenon of agglomeration, so that the electrical characteristics are not uniform. Can be formed and a rough surface roughness can be exhibited, causing problems in transfer of the toner. In addition, when the rotating shaft is inclined, the intermediate transfer belt of a certain thickness cannot be manufactured. However, there is a limit in rotating the high speed by straightening the rotating shaft, which causes a certain thickness deviation.

Therefore, the present invention is to provide an intermediate transfer belt and a method of manufacturing the low surface roughness by preventing the formation of projections on the surface.

In another aspect, the present invention is to provide an intermediate transfer belt and a method of manufacturing the same without low thickness deviation.

In addition, the present invention is to provide an intermediate transfer belt having a uniform electrical characteristics and a method of manufacturing the same.

According to a preferred embodiment of the present invention, a polyimide material in which an electrically conductive filler is uniformly dispersed in a polyamic acid including diamine and dianhydride as a main component, and provides an intermediate transfer belt having a surface roughness (Rz) of less than 0.5 μm. .

In the above embodiment, the conductive filler may be 0.5 to 35% by weight based on the solids content of the polyamic acid solution.

In the above embodiment, the thickness deviation may be 7% or less.

In the above embodiment, the volume resistance value may be 10 ⁵ to 10 ¹² Ωcm.

In the above embodiment, the elastic modulus may be 2.0 ~ 7.0GPa.

According to another preferred embodiment of the invention, preparing a polyamic acid solution; Applying a polyamic acid solution to the mold outer peripheral surface; Rotating the mold to which the polyamic acid solution is applied at a speed of 50 to 200 rpm; And it provides a method for producing a polyimide-based intermediate transfer belt comprising the step of imidating the applied polyamic acid solution.

In the above embodiment, the preparing of the polyamic acid solution may be to disperse the electrically conductive filler in an amount of 0.5 to 35 wt% based on the solids content of the polyamic acid solution.

In the above embodiment, the polyamic acid solution prepared in the step of preparing a polyamic acid solution may have a viscosity of 100 ~ 500 poise.

In this embodiment, the step of rotating the mold may be to rotate the mold for 0.5 to 4 hours.

In the above embodiment, the step of imidization may be to heat treatment at 50 ~ 400 ℃.

The present invention can provide an intermediate transfer belt capable of uniformly transferring toner by preventing surface formation of projections and lowering the surface roughness, and a method of manufacturing the same.

In addition, the present invention can provide an intermediate transfer belt and a method for manufacturing the same in which the thickness is constant without the seam by lowering the thickness deviation.

In addition, the present invention can provide an intermediate transfer belt and a method of manufacturing the same, which have excellent electrical quality by having uniform electrical characteristics.

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

In the intermediate transfer belt of the present invention, in terms of uniformly transferring the toner, the surface roughness (Rz) measured in a state without a separate surface treatment after molding may be less than 0.5 μm.

To this end, the intermediate transfer belt of the present invention may be obtained by applying a polyamic acid solution containing a filler to the mold outer peripheral surface using a roller or the like, followed by heat treatment and imidization.

More specific manufacturing method comprises the steps of preparing a polyamic acid solution; Applying a polyamic acid solution to the mold outer peripheral surface; Rotating the mold to which the polyamic acid solution is applied at a speed of 50 to 200 rpm; And imidizing the applied polyamic acid solution by heat treatment.

In this case, the viscosity of the polyamic acid solution in terms of processability of the preparation may be 100 to 500 poise.

As the roller, a dispenser or a die can be used without limitation, and the coating amount and the coating thickness of the polyamic acid solution are controlled by controlling the discharge rate of the PI varnish. The coating thickness of the polyamic acid solution may be 40 to 200 μm when the mold is heat-treated in a mold to prepare an intermediate transfer belt, and a thickness variation thereof may be 7% or less. When the thickness variation exceeds 7%, the thickness variation of the film is intensified after the polyamic acid solution is imidized, and the developability of the intermediate transfer belt may be reduced. The rotational speed of the mold may be 50 to 200 rpm and the rotation time may be 0.5 to 4 hours in consideration of the coating amount and the coating thickness of the polyamic acid solution, but is not limited thereto.

Alumina, stainless steel, Teflon, etc. may be used as the mold, and the size is not particularly limited, but a length of 200 to 300 mm and an inner diameter of 100 to 150 mm may be used.

After heat treatment stepwise in the mold to which the polyamic acid solution is applied, it may be detached from the mold to prepare a polyimide-based 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 To proceed and complete the imidization, and at the same time prepare a solidified film. In addition, if necessary, after prebaking, the belt can be detached from the mold and inserted into a mold of a slightly smaller size to be post-cured.

In the case of manufacturing the intermediate transfer belt by the manufacturing method as described above, by reducing the rotational force applied to the mold in order to control the thickness of the intermediate transfer belt to prevent the filler from pulling due to the centrifugal force to ensure that the filler is dispersed evenly to the filler agglomeration It is possible to prevent the formation of protrusions in the intermediate transfer belt. Therefore, the surface roughness is low, the electrical characteristics are uniform, and the thickness deviation is small, thereby providing an intermediate transfer belt having excellent developability by transferring the toner uniformly and satisfactorily.

Meanwhile, 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 including a filler, and then applying the same to the mold outer surface using a roller. It is then obtained by heat treatment and imidization.

The diamine component is not particularly limited as long as it is used in the production of polyimide resin, oxydianiline (4,4'-Oxydianiline, ODA), p-phenylenediamine (pPDA), m- Phenylenediamine (meta-phenylene diamine, mPDA), p-methylenediamine (para-Methylene Diamine, pMDA), m-methylenediamine (meta-Methylene Diamine, 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 may be 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).

The conductive fillers included in the preparation of the polyamic acid solution include carbon blacks such as ketjen black, acetylene black and furnace black, metals such as aluminum and nickel, and oxidation such as tin oxide. It may include one or more selected from conductive or semiconductive powders such as metal oxides and potassium titanate, or conductive polymers such as polyaniline or polyacetylene. In addition, the content of the conductive filler is added may include 0.5 to 35% by weight relative to the solids content of the polyamic acid solution in order to obtain the required electrical conductivity. In addition to this, it may further include a metal filler, it may be used 0.1 to 5% by weight based on the solids content of the polyamic acid solution.

The method for dispersing the electrically conductive filler is not particularly limited, and typically, an ultrasonic disperser capable of efficient dispersing may be used, and the filler may be dispersed with an ultrasonic disperser by including a polymer dispersant in the polyamic acid solution. The polymer dispersant is not particularly limited, but may include one or more selected from poly (vinylpyrollidone) and polyacrylate derivatives. The content of the dispersant may be polyamic acid. It may contain 0.05 to 10% by weight based on the solids content of the solution.

The reaction temperature for preparing the polyamic acid solution is 0 ~ 60 ℃, the reaction time may be 0.5 to 12 hours, but is not limited thereto.

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

In addition, the transfer belt of the present invention may have an elastic modulus of 2.0 to 7.0 GPa, preferably 2.5 to 5.0 GPa. If the elastic modulus is too low, mechanical deformation is a concern when used for a long time as an intermediate transfer belt. If the elastic modulus is too 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>

Nitrogen was introduced into a four-necked flask equipped with a mechanical stirrer, reflux condenser, and nitrogen inlet, and then, Ketjenblack 5.07g and PVP (Poly (vinylpyrrolidone)) 1g were added to DMF 1007g and dispersed in an ultrasonic disperser, where 118g BPDA and 80g ODA were added. Was added and reacted at room temperature while continuously dispersing ultrasonic waves to prepare a polyamic acid solution containing Ketjenblack as a conductive filler. The viscosity of this solution was 195 poise at 23 degreeC.

Thereafter, the polyamic acid solution was applied to the outer peripheral surface of the cylindrical stainless steel molding mold rotating at a speed of 100 rpm using a dispenser at a discharge rate of 3g / 10 seconds, and then prebaked at a temperature of 80 ° C. on the belt surface. After removing the remaining solvent and water first, and maintaining the temperature increase rate of 5 ℃ per minute and finally post-curing up to 350 ℃ by seamless conductivity to completely remove the solvent and water remaining on the surface and inside A polyimide-based intermediate transfer belt containing a filler was prepared, and the thickness of the prepared belt was 65 μm.

<Example 2>

In Example 1, the polyamic acid solution was coated on the outer circumferential surface of the cylindrical stainless steel molding mold rotated at a speed of 200 rpm using a dispenser at a discharge rate of 3 g / 10 seconds to prepare an intermediate transfer belt in the same manner.

<Example 3>

In Example 1, the polyamic acid solution was applied to the outer peripheral surface of the cylindrical stainless steel molding mold using a dispenser at a discharge rate of 4 g / 10 seconds, and then an intermediate transfer belt was manufactured in the same manner.

<Example 4>

In Example 1, a polyamic acid solution obtained by adding 6.12 g of ketjen black and 1.2 g of PVP was prepared, and an intermediate transfer belt was prepared after coating in the same manner.

<Example 5>

In Example 1, 87.5 g of PMDA, 80 g of ODA, 4.3 g of Ketjenblack, and 0.8 g of PVP were prepared to prepare a polyamic acid, and the same method was applied to prepare an intermediate transfer belt.

<Example 6>

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 the belt was mounted on a mold having an inner diameter of 4% smaller than the used mold. , And 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. By reacting, a polyamic acid solution containing Ketjenblack, which is a conductive filler, was prepared. The viscosity of this solution was 180 poise at 24 ° C.

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.

Comparative Example 3

In Example 1 was applied to the outer peripheral surface of the cylindrical stainless steel molding mold to rotate the polyamic acid solution at 400rpm using a dispenser at a speed of 3g / 10 seconds to prepare an intermediate transfer belt in the same manner.

<Comparative Example 4>

In Example 1, the polyamic acid solution was coated on the outer circumferential surface of the cylindrical stainless steel molding mold rotated at 30 rpm using a dispenser at a speed of 3 g / 10 sec, to prepare an intermediate transfer belt in the same manner.

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 2.

(1) Surface roughness (Rz)

The surface of the formed optical structure was measured using Carl Zeiss' LSM5 Pascal product, the specific evaluation method is shown in Table 1 below.

Rz; 10 point average roughness

In the section taken from the cross-sectional curve by the reference length, the difference between the average height of the peaks from the highest point to the fifth point and the average height below the valley from the lowest point to the fifth point among the straight lines parallel to the average line. Shown.

(2) thickness and thickness deviation

The thickness was measured by using a micrometer (Anritus, Electronic micrometer) after drying the sample of 20 × 20cm at 100 ℃ for 1 hour and measuring the thickness of the sample 50 times at random locations to remove the largest and smallest values. The value obtained. Thickness variation was expressed in% through the formula for calculating the general thickness variation.

(3) Volume resistance value

Using a resistance meter (HIRESTA UP) manufactured by Mitsubishi Chemical Co., Ltd., a 20 × 20 cm sized sample was installed on a substrate of metal material, and a volume resistance was measured at intervals of 10 seconds for each sample by applying a voltage of 100 V to the sample continuously. It was. At this time, a ring-shaped probe was used, and the measurement was performed 10 times to obtain an average value.

(4) Modulus

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

(5) developability

The intermediate transfer belts prepared in Examples and Comparative Examples were applied to a 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 image 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 Roughness (Rz) (㎛) Thickness (㎛) Thickness deviation (%) Volume Resistance (Ωcm) Modulus of elasticity (GPa) Developability Example 1 0.22 65 2.1 2.73 × 10 ¹⁰ 3.55 Very good Example 2 0.31 63 3.2 1.72 × 10 ¹⁰ 3.69 Very good Example 3 0.36 68 3.3 9.28 × 10 ⁹ 3.78 Very good Example 4 0.45 70 2.9 3.21 × 10 ⁷ 3.82 Very good Example 5 0.23 66 2.0 7.21 × 10 ⁹ 3.57 Very good Example 6 0.42 63 2.7 4.12 × 10 ¹⁰ 2.99 Very good Comparative Example 1 1.15 71 3.0 1.11 × 10 ¹⁰ 3.32 Good Comparative Example 2 1.22 68 3.5 4.12 × 10 ¹⁰ 3.12 Good Comparative Example 3 1.10 67 12.1 3.22 × 10 ¹⁰ 3.03 Bad Comparative Example 4 1.07 69 15.3 9.12 × 10 ⁹ 2.98 Very bad

As a result of measuring the physical properties, it was found that the surface roughness and thickness deviation were changed according to the manufacturing method, thereby affecting developability. In other words, the belt obtained by applying the dispenser to the outside of the cylindrical cylinder has a relatively low surface roughness and thickness deviation compared to the belt obtained by applying the inside of the cylindrical cylinder and rotating at a high speed. Could show sex.

Claims (10)

A polyimide material in which an electrically conductive filler is uniformly dispersed in a polyamic acid containing diamine and dianhydride as main components, wherein the intermediate transfer belt has a surface roughness (Rz) of less than 0.5 µm. The method of claim 1, The intermediate transfer belt, characterized in that it comprises an electrically conductive filler 0.5 to 35% by weight based on the solids content of the polyamic acid solution. The method of claim 1, Polyimide intermediate transfer belt, characterized in that the thickness deviation is 7% or less. The method according to any one of claims 1 to 3, Polyimide intermediate transfer belt, characterized in that the volume resistance value is 10 ⁵ ~ 10 ¹² Ωcm. The method according to any one of claims 1 to 3, Polyimide intermediate transfer belt, characterized in that the elastic modulus is 2.0 ~ 7.0GPa. Preparing a polyamic acid solution; Applying a polyamic acid solution to the mold outer peripheral surface; Rotating the mold to which the polyamic acid solution is applied at a speed of 50 to 200 rpm; And Imidizing the applied polyamic acid solution by heat treatment Method of producing a polyimide intermediate transfer belt comprising a. The method of claim 6, The preparing of the polyamic acid solution may include dispersing the electrically conductive filler in an amount of 0.5 to 35% by weight based on the solids content of the polyamic acid solution. The method of claim 6, The polyamic acid solution prepared in the step of preparing a polyamic acid solution is a method for producing a polyimide intermediate transfer belt, characterized in that the viscosity is 100 ~ 500 poise. The method according to any one of claims 6 to 8, Step of rotating the mold is a method for producing a polyimide intermediate transfer belt, characterized in that for rotating the mold 0.5 to 4 hours. The method according to any one of claims 6 to 8, The imidation step is a method for producing a polyimide intermediate transfer belt, characterized in that the heat treatment at 50 ~ 400 ℃.