KR100739403B1 - Intermediate transfer belt and manufacturing method thereof - Google Patents

Abstract

The present invention relates to an intermediate transfer belt used in a laser printer, a facsimile machine and a copier, and a manufacturing method thereof. The present invention provides a seamless tubular intermediate transfer belt made of silicone-modified polyimide resin and a method for manufacturing the same. It has excellent malleability and antistatic property, and has excellent water repellency and fouling resistance. Thus, it is possible to provide sufficient physical properties as an intermediate transfer belt without adding a fluorine-based resin layer and an adhesive layer for adhesion with a fluorine-based resin as in the prior art. The invention can maximize the efficiency of the process.

Intermediate Transfer Belt, Polyimide, Silicone Resin

Description

Intermediate transfer belt and manufacturing method

The present invention relates to an intermediate transfer belt used in a laser printer, a facsimile machine and a copying machine, and a manufacturing method thereof, and to an intermediate transfer belt made of a silicone-modified polyimide-based resin and a manufacturing method thereof.

In general, in order to be used as intermediate transfer belts such as laser prints, facsimile machines and copiers, water repellency, oil repellency, stain resistance, heat resistance, elastic modulus, release property with paper, antistatic properties, durability and antistatic properties should be excellent. In particular, for the function of transferring the toner of the intermediate transfer belt, a property having an appropriate volume resistance value is required, and when it is lower or higher than the required volume resistance value, their antistatic properties, transfer properties, image characteristics, and releasability And deterioration of physical properties such as fouling resistance may result in a fatal defect of an image defect.

The polyimide film mainly used as an intermediate transfer belt has excellent thermal stability, excellent mechanical and electrical properties, and is very sensitive to moisture, and thus decreases electrical insulation reliability over time. Due to the glass transition temperature, there are many restrictions in processing and relatively easy to charge. In addition, since the volume resistance value is higher than the resistance value required as the intermediate transfer belt, it is difficult to use the intermediate transfer belt due to the excessive resistance value.

In Japanese Patent Laid-Open Publication Nos. 2003-270967 and 2004-255828, a polyamic acid solution, which is a precursor of polyimide, is polymerized, coated on a mold, and heat treated, thereby improving releasability, water repellency, and oil repellent properties with paper. Disclosed is a method of manufacturing a transfer belt by coating a fluorine-based high molecular compound to be heat treated.

However, it is cumbersome to coat the fluorine-based polymer compound on the semi-cured polyamic acid solution again, and an appropriate primer for the adhesion of the polyimide layer and the fluorine-based polymer layer used as the base of these intermediate transfer belts should be selected. However, there are many time, economic and physicochemical constraints for practical use, such as peeling problems due to poor adhesion properties. In addition, there are problems such as process inefficiency and complexity due to the three-layer structure of the polyimide layer, the primer layer, and the fluorine-based high molecular compound layer. That is, the thickness of the spray-coated primer and the fluorine-based polymer compound may not be uniformly formed due to the working environment and other factors, and there is a problem that the efficiency of the work ability is reduced through repeated operations several times.

On the other hand, intermediate transfer belts such as laser printers, facsimile machines, and copiers serve to transfer the toner, so they must be manufactured to be seamless. Conventionally, in order to make the intermediate transfer belt seamlessly, a washing machine method using high-speed rotation using a centrifugal molding method was used. In this way, it was difficult to manufacture a seamless intermediate transfer belt.

Therefore, an object of the present invention is to provide a single-layer intermediate transfer belt made of a polyimide resin.

It is another object of the present invention to provide a method for producing an intermediate transfer belt made of a polyimide resin and which can be produced in a seamless tubular form of a single layer.

The present invention for achieving the above object provides an intermediate transfer belt comprising a silicone-modified polyimide resin containing dianhydride, diamine and silicone resin.

The silicone resin is characterized in that the number average molecular weight is 600 ~ 2,000.

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The silicone-modified polyimide resin is characterized in that it further comprises a conductive filler.

The silicone-modified polyimide resin has a volume resistivity of 1.5 × 10 ⁸ to 8.5 × 10 ¹³ Ωcm, a contact angle of 105 ° to 113 °, and an elastic modulus of 90 to 135 kg / mm 2.

The silicone resin is characterized in that it is contained in 10 to 30% by weight relative to the diamine.

In addition, the present invention comprises the steps of dissolving dianhydride, diamine, silicone resin in an aprotic superpolar solvent to prepare a silicone-modified polyamic acid solution; And it provides a method for producing an intermediate transfer belt comprising the step of imidating by heating the prepared silicone-modified polyamic acid solution in a mold.

The mold is characterized by using a cylindrical structure consisting of a dual structure of the outer cylinder and the inner cylinder.

The preparing of the silicon-modified polyamic acid solution may further include dispersion of the conductive filler.

Heat treatment in the step of imidizing is characterized in that carried out at 60 ~ 400 ℃.

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

The polyimide resin for the intermediate transfer belt of the present invention includes a silicone-modified polyimide resin copolymerized with a silicone resin.

The silicone-modified polyimide-based resin is obtained by dissolving dianhydride, diamine and silicone resin in an aprotic superpolar solvent to prepare a silicone-modified polyamic acid solution, followed by heat treatment and imidization.

At the time of preparing the silicone-modified polyamic acid solution, a conductive filler capable of adjusting the volume resistance value of the polyimide resin is dispersed and reacted at 0 to 30 ° C. for 30 minutes to 12 hours.

The diamine and dianhydride is not particularly limited as long as it is used in the production of polyimide resin, for example, 1,4-phenylenediamine (1,4-PDA), 1,3-phenylenediamine ( 1,3-PDA), 4,4'-methylenedianiline (MDA), 4,4'-oxydianiline (ODA), 4,4'-oxyphenylenediamine (OPDA), and the like, may be used. The dianhydrides include 1,2,4,5-benzenetetracarboxylic dianhydride (PMDA), 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (BTDA), 4, 4'- oxydiphthalic anhydride (ODPA), 4,4'- hexafluoro isopropylidene diphthalic anhydride, etc. can be used. Diamine and dianhydride are normally used in equimolar amounts.

Silicone resins have the properties of organic and inorganic compounds at the same time and are used to impart stain resistance, water repellency, oil repellency, and releasability with paper. Among them, polydimethylsiloxane, polydiphenylsiloxane and copolymers thereof, polymethylphenylsiloxane One or more selected ones may be used, and a number average molecular weight of 600 to 2000 may minimize microphase separation occurring during polyimide polymerization. The content is preferably used to 10 to 30% by weight based on the diamine content.

Particularly preferred silicone resins in the present invention are polydimethylsiloxanes in which both ends are substituted with aminopropyl groups, and polydimethylsiloxane is a compound in which Si and O atoms form a polymer main chain. It is. These are the most commonly used compounds in the silicon industry, with their glass transition temperatures of -123 ° C, the lowest of all known elastomers. In addition, since the siloxane component of the polydimethylsiloxane is separated from the polymer and moved to the air-polymer interface in the polymer compound modified with polydimethylsiloxane due to the nonpolar characteristic and low surface energy, the siloxane component comes out on the surface of various polymers. Due to the polymer surface has excellent water- and oil-repellent properties, release properties, such properties are also observed in two-phase copolymers and mixtures. However, in the present invention, the silicone resin is not limited to polydimethylsiloxane.

In preparing a silicone-modified polyamic acid solution, when the silicone resin is used in an amount less than 10% by weight based on the diamine content, the water repellent and oil repellent properties are not greatly improved, and the effect of improving the resistance to water, which is a disadvantage of the polyimide, is insufficient. , When used in excess of 30% by weight has a problem that the mechanical strength is sharply reduced due to the influence of the silicone resin having a relatively flexible properties compared to the polyimide.

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

As the conductive filler, one or more selected from ketjen black, acetylene black, and furnace black is preferably used in an amount of 2 to 35 wt% based on 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.

In particular, Ketjen Black is a kind of carbon black that can exhibit antistatic properties and semiconductivity, and has excellent conductivity compared to other materials, expresses excellent electrical properties for a small amount of input, and has a very low impurity content. It is preferable to use for this invention.

Meanwhile, the metal filler may use a material such as Dentall TM-200 doped (supported) with aluminum, nickel, silver or mica.

The prepared polydimethylsiloxane-modified polyamic acid solution is added to a mold and heat-treated to imidize.

The mold is not particularly limited, but a cylindrical mold is used in order to prevent the intermediate transfer belt of the present invention from being seamless, and preferably a cylindrical Teflon mold composed of a double structure of an outer cylinder and an inner cylinder. Therefore, the thickness of the belt can be adjusted using the difference between the diameter of the outer cylinder and the inner cylinder, the preferred thickness of the belt is 40 ~ 200㎛.

The heat treatment is performed stepwise at 60 ~ 400 ℃, first pre-baking (pre-baking) at 60 ~ 80 ℃ 10 to 120 minutes to remove the solvent and water remaining on the surface first. After maintaining the temperature increase rate of 2 ~ 10 ℃ per minute and finally post-curing to 350 ~ 400 ℃ by completely removing the solvent and water present on the surface proceeds and completes the imidization and at the same time solidified Prepare the transfer belt of the film.

The fabricated transfer belt has a volume resistance value in the range of 10 ⁸ to 10 ¹² Ωcm, which is inherently intermediate resistance value, specifically 1.5 × 10 ⁸ to 8.5 × 10 ¹³ Ωcm, and thus antistatic, antistatic and printing It is possible to manufacture intermediate transfer belts for semi-conductive laser printers, facsimiles and copiers with improved performance.

In addition, the manufactured transfer belt is preferably a contact angle of 105 ° ~ 113 °. Here the contact angle refers to the angle that the liquid has when it is thermodynamically equilibrated on the solid surface, measured by the droplets sessile on the solid surface, the low contact angle indicates that the sample is hydrophilic, and the high contact angle indicates that the sample is hydrophobic. That means having In general, in the case of polyimide-based polymer compounds, their contact angles have a contact angle of less than 20 ° to 70 °, so that the water and oil repelling properties are deteriorated, thereby exhibiting properties that are very vulnerable to moisture. There is a need to improve the resistance to moisture.

In addition, it is preferable that the transfer belt of the present invention has an elastic modulus of 90 to 135 kg / mm 2. If the elastic modulus is low, there is a concern that mechanical deformation may occur when used for a long time as an intermediate transfer belt, and if the elastic modulus is high, mechanical strength is deteriorated.

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>

Injecting nitrogen into a four-necked flask equipped with a mechanical stirrer, a reflux condenser and a nitrogen inlet, 47 g of PMDA and 43 g of 4,4-oxydianiline were dissolved in 380 g of an aprotic superpolar solvent, with a number average molecular weight. A polydimethylsiloxane having an aminopropyl group introduced into a sock end of 600 was added in an amount of 10% by weight based on the weight of 4,4-oxydianiline and completely dissolved. 2 wt% KetjenBlack and 0.5 wt% Dentall TM-200 based on the total solute weight as the conductive filler were reacted at room temperature for 1 hour while dispersed in the solution through an ultrasonic disperser to modify the polydimethylsiloxane containing the conductive filler. Polyamic acid solution was prepared.

After the polydimethylsiloxane modified polyamic acid solution prepared above was introduced into a cylindrical Teflon mold composed of a double structure of an outer cylinder and an inner cylinder, prebaking was performed at 70 ° C. for 1 hour to first remove the solvent and water remaining on the belt surface. , The inner cylinder was separated from the outer cylinder. Thereafter, by post-curing to 350 ° C. while maintaining a temperature increase rate of 5 ° C. per minute, the solvent and water remaining on the surface and inside were completely removed.

The prepared polydimethylsiloxane modified polyimide intermediate transfer belt had a thickness of 65 μm.

<Example 2>

A polydimethylsiloxane-modified polyimide-based intermediate transfer belt was prepared in the same manner as Example 1 except that Dentall TM-200 was not used as the conductive filler.

<Example 3>

A polydimethylsiloxane-modified polyimide-based intermediate transfer belt was prepared in the same manner, except that 30 wt% of polydimethylsiloxane was added to the weight of 4,4-oxydianiline in Example 1.

Comparative Example 1

A polyimide intermediate transfer belt containing a conductive filler was prepared in the same manner as in Example 1 except that polydimethylsiloxane having aminopropyl group introduced into the sock end was not added.

Comparative Example 2

A polyimide-based intermediate transfer belt was prepared in the same manner as in Comparative Example 1, and after applying a primer, which is a silicone-based component, by spraying, 2% by weight of ketjen black and 0.5% by weight of Dentall TM-200 were contained. The siloxane was spray coated three times. Finally, after the spray coating, the sample was cured at 350 ° C. for 10 to 60 minutes to prepare a silicone-modified polyimide-based intermediate transfer belt of three layers of polyimide, primer, and polydimethylsiloxane.

Physical properties of the intermediate transfer belt prepared in the above Examples and Comparative Examples were evaluated by the following method.

(1) volume resistance

     Using a resistance meter manufactured by Mitsubishi Chemical, voltage was continuously applied to the sample. The voltage applied to the sample was measured while varying the voltage to 10V, 100V, 250V, 500V and 1000V. In addition, the sample was installed on a substrate (substrate) of the metal material in order to measure the volume resistance, and measured at intervals of 10 to 30 seconds for each sample, wherein a ring-shaped probe (probe) was used.

(2) contact angle

In order to measure the water repellent and oil repellent properties of the silicone-modified polyimide intermediate transfer belt, their contact angles were measured. The contact angle was measured using DCA 3115, CAHN's Dynamic Contact Angle Meter, at room temperature of 25 ° C. The solution was dipped in deionized distilled water and 6 µl of ethylene glycol on the surface of the sample in the form of a sessile drop, and the contact angle was measured through a monitor showing the enlarged interface between the sample surface and the droplet. Was obtained.

(3) elastic modulus

The elastic modulus of the silicone-modified polyimide intermediate transfer belt was measured according to JIS K 6301 using Instron's universal testing machine Model 1000.

Volume resistance (Ω㎝) Contact angle (°) Modulus of elasticity (kg / ㎡) Example 1 1.53 × 10 ⁸ 107 131.4 Example 2 3.57 × 10 ¹⁰ 105 129.7 Example 3 8.19 × 10 ¹³ 113 98.9 Comparative Example 1 2.3 × 10 ¹⁰ 46 130 Comparative Example 2 5.7 × 10 ¹⁰ 105 87.5

As a result of measuring the physical properties, in the case of Comparative Example 1, the volume resistance value is satisfactory for the intermediate transfer belt, but the contact angle is 46 °.

In addition, the comparative example 2 in which the polydimethylsiloxane was physically spray-coated, compared with Examples 1 to 3, in which the silicon compound was chemically introduced into the polyimide main chain, reduced the modulus of elasticity for a long time as an intermediate transfer belt. Mechanical deformation may be a concern during use.

Examples 1 to 3 according to the present invention, among the above example 1 can be said to be the most preferable in terms of electrical properties, moisture resistance and mechanical strength.

As described above, the present invention can provide an intermediate transfer belt of a single layer using a silicone-modified polyimide resin, and thus has excellent electrical characteristics and water repellency, and has an appropriate mechanical strength. The intermediate transfer belt can provide sufficient physical properties without adding an adhesive layer for adhesion, thereby maximizing process efficiency.

Claims (10)

(Correction) An intermediate transfer belt comprising a silicone-modified polyimide-based resin containing dianhydride, diamine and silicone resin . (delete) (Correction) The method according to claim 1, The silicone resin is the intermediate transfer belt, characterized in that the number average molecular weight of 600 ~ 2,000. The method of claim 1, The silicone-modified polyimide resin is an intermediate transfer belt, characterized in that it further comprises a conductive filler. The method of claim 1, The silicone-modified polyimide resin has a volume resistivity of 1.5 × 10 ⁸ to 8.5 × 10 ¹³ Ωcm, a contact angle of 105 ° to 113 °, and an elastic modulus of 90 to 135 kg / mm 2. belt. (Correction) According to claim 1 , The silicone resin is an intermediate transfer belt, characterized in that contained in 10 to 30% by weight based on the diamine . Preparing a silicone-modified polyamic acid solution by dissolving dianhydride, diamine and silicone resin in an aprotic superpolar solvent; And Method of producing an intermediate transfer belt comprising the step of imidizing the prepared silicone-modified polyamic acid solution by heat treatment. The method of claim 7, wherein The mold is a manufacturing method of the intermediate transfer belt, characterized in that using a cylindrical structure consisting of a double structure of the outer cylinder and the inner cylinder. The method of claim 7, wherein The manufacturing method of the silicon-modified polyamic acid solution further comprises the dispersion of the conductive fillers. The method of claim 7, wherein The heat treatment in the step of imidizing the manufacturing method of the intermediate transfer belt, characterized in that carried out at 60 ~ 400 ℃.