JP2005024873A - Semiconductive belt and method for manufacturing semiconductive belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductive belt which has the favorable uniformity of mechanical characteristics and electric resistance and which has improved productivity and solves problems relating to the appearance such as the warpage of the belt and cracks on the surface, and to provide a method for manufacturing the semiconductive belt. <P>SOLUTION: The belt is endless and is used for an electrophotographic image forming apparatus. The endless belt has an outer layer (a) and an inner layer (b), both the outer layer (a) and the inner layer (b) essentially comprising a polyimide resin. The coefficient of linear expansion of the inner layer (b) at 10 to 250°C is smaller than the coefficient of linear expansion of the die metal used for the manufacture of the endless belt. The coefficient of linear expansion of the outer layer (a) is larger than that of the inner layer (b). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００７３】
表１の結果から、本発明の実施例１〜３の半導電性ベルトは、平面度に優れ、転写面の表面硬度が小さいため、ホロキャラクターなどの画質欠陥がなく、優れた画質を長期にわたり安定して得ることができた。一方、比較例１は、レジずれの問題があり、本発明の方法でポリイミドベルトを成型する場合には、金型からの離型性に問題があり、水分を加えて吸水膨張により離型性の改善が必要であった。比較例２は、平面度が悪く、転写面の表面微小硬度が４０と硬いために、ホロキャラクターに問題があった。
【００７４】
【発明の効果】
本発明によれば、平面度に優れ、ホロキャラクター、ブラー、レジずれのない高画質を得ることのできる半導電性ベルトを安価に製造することができ、また、前記半導電性ベルトを備え、高品質の転写画質を安定して得ることができる画像形成装置を提供することができる。
【００７５】
【図面の簡単な説明】
【図１】本発明のベルト状中間転写体を用いたカラー画像形成装置を示す概略図である。
【図２】本発明のベルト状中間転写体を用いたカラー画像形成装置を示す概略図である。
【図３】本発明のベルト構成を示す断面図である
【図４】体積抵抗率の計測方法を示す図である。
【図５】表面層の表面微小硬度の測定原理を示す模式図である。
【図６】ポリイミドベルトの周長と金属製芯体（金型）の外径との関係を示す図である。
【図７】ベルトの平面度を計測する装置の概略構成図である。
【図８】本発明で用いたポリイミド液を塗布する装置の概略構成図である。
【符号の説明】
１ 感光体ドラム（像担持体）
２ 中間転写ベルト（中間転写体）
３ バイアスローラ（第二転写手段）
４ 用紙トレー
５ ブラック現像器
６ イエロー現像器
７ マゼンタ現像器
８ シアン現像器
９ 中間転写体クリーナ
１０ 転写ローラ
１３ 剥離爪
１４ 搬送ベルト
１６ 感光体クリーナ
２１ ベルトローラ
２２ バックアップローラ
２３ ベルトローラ
２４ ベルトローラ
２５ 導電性ローラ（第一転写手段）
２６ 電極ローラ
３０ 中間転写ドラム
３１ クリーニングブレード
４１ 記録紙
４２ ピックアップローラ
４３ フィードローラ
７１ トナーカートリッジ
７２ 定着ローラ
７３ バックアップローラ
７４ テンションローラ
７５ ２次転写ローラ
７６ 用紙経路
７７ 用紙トレイ
７８ レーザー発生装置
７９ 感光体
８０ １次転写ローラ
８１ 駆動ローラ
８２ 転写クリナー
８３ 帯電ローラ
８４ 感光体クリ−ナー
８５ 現像器
８６ 中間転写体
８８ 除電ローラ
Ｔ トナー像[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductive belt used in an image forming apparatus using an electrophotographic system such as a copying machine or a printer, and a method for manufacturing the same.
[0002]
[Prior art]
An image forming apparatus using an electrophotographic method forms a uniform charge on an image carrier, which is a photoconductive photosensitive member made of an inorganic or organic material, and uses an electrostatic image with a laser beam or the like that modulates an image signal. Then, the electrostatic latent image is developed with a charged toner to obtain a visualized toner image. Then, the toner image is electrostatically transferred to a transfer material such as a recording sheet through an intermediate transfer member or a required reproduction image is obtained. Further, there is known an image forming apparatus that employs a system in which the toner image formed on the image carrier is primarily transferred to an intermediate transfer member, and the toner image on the intermediate transfer member is secondarily transferred to a recording sheet (for example, , See Patent Document 1).
[0003]
As a semiconductive belt that can be used for such an intermediate transfer belt, a transfer conveyance belt, and the like, for example, a semiconductive belt in which a conductive agent is dispersed in a polyimide resin having excellent mechanical properties and heat resistance has been proposed ( For example, see Patent Document 2 and Patent Document 3.)
[0004]
However, since this semiconductive belt is mainly composed of a single layer type, when used as an intermediate transfer belt or transfer conveyance belt, the balance between flexibility and rigidity is poor, and as an intermediate transfer belt or transfer conveyance belt, Could not be said to satisfy the characteristics. In order to improve this, for example, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, p-phenylenediamine, and polyamide (U varnish-S), which is a polymer, are used as a raw material for the polyimide resin. Discloses a belt in which a conductive filler is dispersed (for example, see Patent Document 4). This type of intermediate transfer belt is excellent in mechanical properties, has no belt deformation due to stress during driving, and can stably obtain a high-quality transfer image without color misregistration. However, since the polyimide resin material is excellent in mechanical characteristics in the transfer portion, primary transfer is performed by electrostatically transferring the toner image by pressing the recording paper against the recording medium using a bias roller and applying an electric field. Since the deformation due to the pressing force by the bias roller at the part is small, the pressing force by the bias roller is concentrated. For this reason, the toner agglomerates and the charge density becomes high, thereby causing internal discharge of the toner layer and changing the polarity of the toner. There was a thing.
[0005]
In order to solve such problems, a method has been proposed in which a semiconductive belt made of polyimide is formed of a plurality of layers, and the electrical characteristics of each layer are individually adjusted to improve electrical characteristics and mechanical characteristics. . For example, a semiconducting belt has been proposed in which variations in electrical resistance and reduction in mechanical strength are improved by providing a plurality of layers mainly composed of polyimide resin and having different surface resistivity (for example, patents) Reference 5). This belt is manufactured by applying a polyamide solution, which is a raw material solution of the first layer, to a cylindrical inner surface, solidifying by removing a solvent to some extent under a temperature condition in which imide conversion is not performed, After applying the second layer of raw material liquid to the inner surface of one layer and drying the solvent, the belt-like material is peeled off from the inner surface of the cylindrical shape, and then the belt-like material has a rod body having an outer diameter smaller than the inner diameter. After inserting into the belt-like material, imide conversion of both layers is performed simultaneously.
[0006]
However, when a multilayer belt is produced by the above-described manufacturing method, solvent drying must be performed for each layer. After the belt-like material is peeled off from the cylindrical inner surface and the rod is inserted into the belt-like material, There is a disadvantage that productivity is not good because of the imide conversion.
In addition, since the two layers having a large difference in residual solvent amount must be dried at the same time, the belt is likely to warp due to the difference in residual stress, and in extreme cases, the belt surface may be cracked. There are problems that arise.
[0007]
On the other hand, there are steps of applying a plurality of raw material liquids containing polyamide, removing a solvent from the coating film, and imido conversion of polyamide, and at least one polyimide resin layer containing a conductive substance In a method for manufacturing a semiconductive belt, a method is proposed in which the plurality of raw material liquids are sequentially or simultaneously applied almost uniformly, and then the solvent is removed simultaneously in each layer (see, for example, Patent Document 6). .
[0008]
Productivity is improved because the solvent drying process can be performed once, but mixing between layers due to movement of the conductive material is unlikely to occur at the interface of each layer, so the liquid viscosity of the polyamide needs to be high. Since it is difficult to apply the solution smoothly, it is difficult to make the thickness uniform and the flatness of the belt is deteriorated. When carbon black is dispersed because it is a highly viscous liquid, it is difficult to remove air entrained in the liquid, and the air in the liquid generates protrusions on the belt surface during the imide conversion process. May cause problems.
[0009]
[Patent Document 1]
JP-A-62-206567
[Patent Document 2]
JP-A-5-77252
[Patent Document 3]
Japanese Patent Laid-Open No. 10-63115
[Patent Document 4]
Japanese Patent Laid-Open No. 10-63115
[Patent Document 5]
JP 7-156287 A
[Patent Document 6]
JP 2002-029837 A
[0010]
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to provide an intermediate transfer belt that has excellent uniformity in mechanical characteristics and electrical resistance value, improved productivity, and improved appearance problems such as belt warpage, surface cracks, and protrusions. Another object of the present invention is to provide a semiconductive belt useful as a transfer / conveying belt and a method for producing the semiconductive belt.
[0011]
[Means for Solving the Problems]
Means for solving the above problems are as follows.
<1> An endless belt used in an electrophotographic image forming apparatus, wherein the endless belt has an outer layer (a) and an inner layer (b), and the outer layer (a) and the inner layer (b) Is mainly composed of a polyimide resin, and the linear expansion coefficient of the inner layer (b) at 10 to 250 ° C. is smaller than the linear expansion coefficient of the metal mold used for the production of the endless belt, and the outer layer than the inner layer (b). A semiconductive belt characterized in that the linear expansion coefficient of (a) is large.
<2> An endless belt used in an electrophotographic image forming apparatus, wherein the endless belt has an outer layer (a) and an inner layer (b), and the outer layer (a) and the inner layer (b) Is mainly composed of polyimide resin, and the linear expansion coefficient of the inner layer (b) at 10 to 250 ° C. is 23 ppm / ° C. or less, and the linear expansion coefficient of the outer layer (a) is larger than that of the inner layer (b). Characteristic semi-conductive belt.
<3> In the linear expansion coefficient at 10 ° C. to 250 ° C., the difference between the outer layer (a) and the inner layer (b) is 50 ppm / ° C. or less, and the linear expansion coefficient of the outer layer is larger than that of the inner layer. The semiconductive belt according to <1> or <2>.
<4> The semiconductive belt according to any one of <1> to <3>, wherein the thickness ratio of the outer layer (a) is 10% to 50% of the total thickness of the belt. .
<5> The semiconductivity according to any one of <1> to <4>, wherein the diamine that is a raw material of the polyimide resin of the inner layer (b) contains p-phenylenediamine as a main component. belt.
<6> The diamine which is a raw material of the polyimide resin of the outer layer (a) contains 4,4′-diaminophenyl ether as a main component, and is described in any one of <1> to <5> Semi-conductive belt.
<7> The method for producing a semiconductive belt according to any one of claims 1 to 6, wherein a polyamide solution for forming the inner layer (b) is applied to the outer peripheral surface of the metal core, and the endless belt A belt-shaped polyimide precursor is formed, then a polyamide solution for forming the outer layer (a) is applied, an endless belt-shaped polyimide precursor is laminated to form an endless belt, and then the endless belt A method for producing a semiconductive belt, wherein the material is cured by heating.
<8> The polyamide solution for forming the inner layer (b) and the polyamide solution for forming the outer layer (a) both have a solution viscosity at 25 ° C. in a B-type viscometer of 10 Pa · s or more and 80 Pa · The method for producing a semiconductive belt according to <7>, wherein the method is within a range of s or less.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
<Semiconductive belt>
In the semiconductive belt of the present invention, a polyamide solution, which is a raw material liquid for an inner layer polyimide resin, is applied to the outer peripheral surface of a metal core to form an endless belt-like polyimide precursor, and then an outer layer polyimide It is obtained by applying a polyamide solution, which is a raw material solution of a resin, laminating and forming an endless belt-like polyimide precursor to form an endless belt-like product, and then curing it by heating.
[0013]
In the present invention, the linear expansion coefficient of the inner layer (b) at 10 ° C. to 250 ° C. is smaller than the linear expansion coefficient of the metal used for the metal core.
FIG. 6 is a diagram showing the relationship between the circumference of the polyimide belt and the outer diameter of the metal core (mold) in the present invention. In the heating step {circle around (1)}, the belt circumferential length is deformed following the metal core, and therefore becomes the same as the outer diameter of the metal core. By heating, the polyamide solution coated on the outside of the metal core promotes solvent removal and imidization reaction, and the belt circumference is restricted to the outer diameter of the metal core in the temperature range of 250 ° C. To be determined. In the heating step (2), since the thermal expansion coefficient of the metal core is larger than that of polyimide, the polyimide belt circumference is deformed by stress as the outer diameter of the metal core expands. (When there is no metal core, it expands along the line shown by the dotted line in FIG. 6). In the cooling step (3), the circumference of the polyimide belt shrinks with the shrinkage of the outer diameter of the metal core, but in the cooling step (4), the thermal expansion coefficient of the polyimide belt becomes smaller than that of the metal core. Since it is smaller than the thermal expansion coefficient, the peripheral length of the polyimide belt is larger than the outer diameter of the metal core at normal temperature (ΔL in FIG. 6). When ΔL> 0, the polyimide belt can be easily removed from the metal core.
[0014]
Here, the linear expansion coefficient in 10 degreeC-250 degreeC of the aluminum material often used as a metal core body is 24 ppm / degreeC. The linear expansion coefficient of the aluminum material depends on the literature (Table 2 Physical Properties of Practical Metal Materials). In this case, in the two-layer polyimide belt, the value of ΔL in FIG. 6 becomes a positive value by setting the linear expansion coefficient at 10 to 250 ° C. of the polyimide resin material constituting the inner layer to 23 ppm / ° C. or less. Therefore, in the cooling step, the outer diameter of the polyimide belt is larger than the outer diameter of the metal core, so that the two-layer polyimide belt can be easily removed from the metal core.
That is, when an aluminum material is used as the metal core, the semiconductive belt is an endless belt having an outer layer (a) and an inner layer (b) mainly composed of a polyimide resin, and the inner layer (b) The polyimide resin material has a linear expansion coefficient at 10 to 250 ° C. of 23 ppm / ° C. or less, and a larger linear expansion coefficient of the outer layer (a) than that of the inner layer (b). In addition, a semiconductive belt free from appearance defects can be obtained.
[0015]
Even when the metal core is made of a material other than aluminum, the same effect can be obtained if the linear expansion coefficient of the inner layer (b) at 10 ° C. to 250 ° C. is smaller than the linear expansion coefficient of the mold metal used for belt production. Is obtained.
[0016]
<Linear expansion coefficient>
The linear expansion coefficient was obtained by cutting out a test piece having a width of 3 mm and a length of 10 mm from the semiconductive belt, and using a thermal analysis apparatus TMA-50 manufactured by Shimadzu Corporation as an evaluation sample. Minute, load 2 g, measured in a temperature range of 10 ° C. to 250 ° C., and the linear expansion coefficient at 10 ° C. to 250 ° C. was determined from the result. The linear expansion coefficient at 10 ° C. to 250 ° C. refers to the linear expansion coefficient at each temperature.
When an aluminum material is used as the metal core, the linear expansion coefficient of the inner layer (b) is preferably 23 ppm / ° C. or less. More preferably, they are 20 ppm / degrees C or more and 23 ppm / degrees C or less, More preferably, they are 15 ppm / degrees C or more and 20 ppm / degrees C or less.
[0017]
Moreover, the linear expansion coefficient (a1) in each temperature of 10-250 degreeC of the outer layer (a) of the polyimide resin belt material which comprises an inner layer (b), and the line in each temperature of 10-250 degreeC of an inner layer (b) As for the relationship with the expansion coefficient (b1), a1 must be larger than b1. Preferably, the difference between a1 and b1 is 50 ppm / ° C. or less, and more preferably 35 ppm / ° C. or less. Since the linear expansion coefficient of the outer layer is slightly larger than that of the inner layer, it is possible to alleviate stress non-uniformity at the time of belt molding and to obtain a belt with high accuracy flatness.
[0018]
(Flatness)
The flatness of the semiconductive belt of the present invention is 4 mm or less, preferably 2 mm or less. When the flatness exceeds 4 mm, the adhesion between the driving roll for driving the belt and the semiconductive belt changes, and as a result, the moving speed of the belt fluctuates. The moving speed of the intermediate transfer member is different for each color, so that high-precision image alignment is impossible, and image defects such as color misregistration may occur.
As shown in FIG. 7, the flatness in the present invention is such that the semiconductive belt is stretched by applying a load of 4 kg with two parallel axes (Φ28 mm), and the surface of the semiconductive belt (2 In the case of a layer structure, the laser displacement meter is parallel to the center of the shaft that is paired with the shaft on which the surface of the outer layer) is stretched by a laser displacement meter 17 (LK-030 manufactured by Keyence). 17, the difference between the maximum value and the minimum value of the displacement amount of the belt surface is read.
[0019]
By setting it as the said structure, the belt whose flatness is smooth can be obtained easily. Moreover, the balance of flexibility and rigidity that cannot be obtained with a single material structure can be satisfied. The material that constitutes the transfer surface has low surface hardness, line images are not clear (holocharacter), and toner is scattered (blur). Obtainable.
[0020]
<Inner layer polyimide resin>
The inner layer polyimide resin in the present invention is not particularly limited as long as a carboxylic acid having an aromatic skeleton and a diamine are polymerized. Preferably, the main component is a polymer formed by imide bonding between a wholly aromatic skeleton that is a tetracarboxylic acid residue and a p-phenylene skeleton that is a diamine residue. By using a polyimide resin having a p-phenylene skeleton in the diamine residue as a main component, the resin becomes rigid and can satisfy mechanical properties of Young's modulus of 4000 MPa or more. Examples of the diamine component having a p-phenylene skeleton include compounds in which hydrogen atoms of p-phenylenediamine or aromatic rings thereof are substituted with lower alkyl groups and the like. In the present invention, if a polymer having a Young's modulus of 4000 MPa or more and a p-phenylene skeleton having an imide bond as a main component is used, a polymer having a diphenyl ether skeleton, which is a diamine residue described later, formed by an imide bond. May be used in combination.
[0021]
<Polyimide resin of outer layer>
The polyimide resin of the outer layer in the present invention is not particularly limited as long as a carboxylic acid having an aromatic skeleton and a diamine are polymerized. Preferably, the main component is a polymer formed by imide bonding between a wholly aromatic skeleton that is a tetracarboxylic acid residue and a diphenyl ether skeleton that is a diamine residue. By using a polyimide resin having an ether skeleton in the diamine residue as a main component, the surface microhardness of the polyimide resin surface can have flexibility of 30 degrees or less. Examples of the diamine component having a diphenyl ether skeleton include 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, and compounds obtained by substituting these aromatic rings with lower alkyl groups. In the present invention, if the surface hardness is 30 degrees or less and a polymer formed by imide bonding of the diphenyl ether skeleton is a main component, the diamine residue and the p-phenylene skeleton, which will be described later, are imide bonded. These polymers may be used in combination.
[0022]
Examples of the tetracarboxylic dianhydride having a wholly aromatic skeleton include pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,3,3 ′, 4. '-Biphenyltetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,4,5,8- Examples thereof include naphthalenetetracarboxylic dianhydride or compounds obtained by substituting these aromatic rings with lower alkyl groups. Of these, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride is particularly preferable.
[0023]
<Surface micro hardness>
In the semiconductive belt of the present invention, the hardness of the transfer surface (in the case of a two-layer belt, the surface of the outer layer) is preferably 30 or less, more preferably 25 or less in terms of surface microhardness. The surface microhardness is not a method of obtaining the diagonal length of the indentation like the Vickers hardness widely used for measuring the hardness of metal materials, but how much the indenter has entered the sample. It can be determined by the measurement method. When the test load P (mN) and the amount of penetration of the indenter into the sample (indentation depth) D (μm), the surface microhardness DH is defined by the following formula (1).
Formula (1) DH≡αP / D²
Here, α is a constant depending on the shape of the indenter, and α = 3.8854 (used indenter: in the case of a triangular pyramid indenter).
[0024]
This surface microhardness is the hardness obtained from the excessive weight and indentation depth in the process of indenting the indenter, and represents the strength characteristics of the material including not only plastic deformation of the sample but also elastic deformation. is there. In addition, the measurement area is very small, and more accurate hardness measurement is possible within a range close to the toner particle diameter. The present inventors have found that there is a very accurate correlation between the surface microhardness obtained here and the generation level of the holocharacter. That is, when the surface microhardness of the transfer surface of the intermediate transfer member is preferably 30 or less, more preferably 25 or less, the transfer surface of the intermediate transfer member is deformed by the pressing force of the bias roller in the secondary transfer portion described above. As a result, the pressing force concentrated on the toner on the intermediate transfer member is dispersed. For this reason, the toner does not aggregate, and image quality defects such as holocharacters in which the line image is lost do not occur.
[0025]
The surface microhardness on the transfer surface of the semiconductive belt was determined by the following method. A sheet of material (surface layer) constituting the transfer surface is cut to about 5 mm square, and the small piece is fixed to the glass plate with an instantaneous adhesive. The surface microhardness of the surface of this sample is measured using an ultra micro hardness meter DUH-201S (manufactured by Shimadzu Corporation). The measurement conditions are as follows.
Measurement environment: 23 ° C, 55% RH
Working indenter: Triangular pyramid indenter
Test mode: 3 (soft material test)
Test load: 0.70 gf
Load speed: 0.0145 gf / sec
Holding time: 5 sec
[0026]
The relationship between the Young's modulus of the semiconductive belt material (the material used for the belt-like inner layer material) and the amount of displacement of the belt due to disturbance (load fluctuation) during belt driving can be expressed by the following equation (2).
Formula (2) Δl = P · l · α / (t · w · E)
Where Δl: belt displacement (μm)
P: Load (N)
l: Belt length between two tension rolls (mm)
α: Coefficient
t: Belt thickness (mm)
w: Belt width (mm)
E: Young's modulus of belt material (N / mm²).
[0027]
The expansion / contraction (displacement amount) of the belt due to disturbance (load fluctuation) during driving of the belt is inversely proportional to the Young's modulus and thickness of the belt material. When a belt material with a high Young's modulus is used, the amount of displacement of the belt due to disturbance (load fluctuation) during driving of the belt is reduced, and deformation of the belt with respect to stress during driving is reduced, so that good image quality can be stably obtained. . However, as the thickness of the belt increases, the amount of deformation of the outer surface of the belt at the belt bending portion such as the drive train roll increases, and it is difficult to obtain good image quality. Also, the amount of deformation between the outside and inside of the belt And the belt may be broken due to local repeated stress.
[0028]
The total thickness of the semiconductive belt of the present invention is 0.05 mm or more and 0.2 mm or less, preferably 0.06 mm or more and 0.15 mm or less. The thickness ratio of the outer layer is 10 to 50% of the total thickness. When the thickness of the outer layer is in the above range, the pressing force concentrated on the toner on the semiconductive belt is dispersed without being affected by the polyimide material of the inner layer. For this reason, the toner does not aggregate, and image quality defects such as holocharacters in which the line image is lost do not occur. Since the Young's modulus of the material of the belt inner layer is 4000 MPa or more, the mechanical properties as a belt base material can be satisfied.
[0029]
It is preferable that the polyimide resin of the inner layer contains a conductive agent. More preferably, the inner layer and outer layer polyimide resins contain a conductive agent. The conductive agent is preferably contained in the polyimide resin in a dispersed state. As the conductive agent, there is no particular limitation as long as the electric or semiconductive fine powder can be used and a desired electric resistance can be stably obtained. However, carbon black such as Ketchen black and acetylene black, aluminum and Examples thereof include metals such as nickel, metal oxide compounds such as tin oxide, and potassium titanate. These may be used alone or in combination.
[0030]
In the present invention, it is proposed to add oxidized carbon black having a pH of 5 or less as a conductive agent. Since the carbon black has good dispersibility in the resin, good dispersion stability can be obtained. Therefore, the resistance variation of the semiconductive belt can be reduced, the electric field dependency is also reduced, the electric field concentration due to the transfer voltage hardly occurs, and the stability of the electric resistance with time is improved.
[0031]
(Oxidized carbon black)
Oxidized carbon black can be produced by oxidizing carbon black to impart a carboxyl group, a quinone group, a lactone group, a hydroxyl group, or the like to the surface. This oxidation treatment is an air oxidation method in which contact is made with air in a high-temperature atmosphere to react, a method of reacting with nitrogen oxides or ozone at room temperature, and air oxidation at high temperature, followed by ozone oxidation at a low temperature. It can be performed by a method or the like. Specifically, the oxidized carbon black can be produced by a contact method. Examples of the contact method include a channel method and a gas black method. Oxidized carbon black can also be produced by a furnace black method using gas or oil as a raw material. If necessary, after these treatments, a liquid phase oxidation treatment with nitric acid or the like may be performed. Acidic carbon black can be produced by a contact method, but is usually produced by a closed furnace method. In the furnace method, only carbon black having a high pH and a low volatile content is usually produced, but the pH can be adjusted by subjecting it to the above-mentioned liquid phase acid treatment. For this reason, the carbon black obtained by the furnace method manufacturing and adjusted to have a pH of 5 or less by the post-treatment is also considered to be included in the present invention.
[0032]
The pH value of the oxidized carbon black of the present invention is pH 5.0 or less, preferably pH 4.5 or less, more preferably pH 4.0 or less. Oxidized carbon having a pH of 5.0 or less has an oxygen-containing functional group such as a carboxyl group, a hydroxyl group, a quinone group, and a lactone group on the surface, so that it has good dispersibility in the resin and good dispersion stability is obtained. . Accordingly, the resistance variation of the semiconductive belt can be reduced, and the electric field dependency is also reduced, so that the electric field concentration due to the transfer voltage hardly occurs.
[0033]
It is obtained by adjusting an aqueous suspension of carbon black and measuring with a glass electrode. Moreover, pH of acidic carbon black can be adjusted with conditions, such as processing temperature in an oxidation treatment process, and processing time.
[0034]
The oxidation-treated carbon black contains 1% by mass to 25% by mass, preferably 2% by mass to 20% by mass, and more preferably 3.5% by mass to 15% by mass. Is preferred. When the volatile content is less than 1% by mass, the effect of the oxygen-containing functional group attached to the surface is lost, and the dispersibility in the binder resin may be reduced. On the other hand, if it is higher than 25% by mass, it will decompose when dispersed in the binder resin, or the amount of water adsorbed on the oxygen-containing functional group on the surface will increase. Problems such as poor appearance may occur. Therefore, the dispersion | distribution in binder resin can be made more favorable by making a volatile content into the said range. This volatile content can be determined from the ratio of organic volatile components (carboxyl group, hydroxyl group, quinone group, lactone group, etc.) that come out when carbon black is heated at 950 ° C. for 7 minutes.
[0035]
In the polyimide belt of the present invention, two or more types of carbon black may be contained. At this time, these carbon blacks are preferably substantially different in conductivity from each other. For example, those having different physical properties such as the degree of oxidation treatment, the amount of DBP oil absorption, and the specific surface area by the BET method using nitrogen adsorption are used. . When two or more types of carbon blacks having different conductivity are added in this way, for example, carbon black that expresses high conductivity is preferentially added, and then carbon black with low conductivity is added to adjust the surface resistivity. It is possible to do. Even when two or more types of carbon black are contained in this way, the mixing and dispersion of both carbon blacks can be enhanced by using the oxidized carbon black as at least one of them.
[0036]
Specific examples of the oxidation-treated carbon black include “Printex 150T” (pH 4.5, volatile content 10.0% by mass) and “Special Black 350” (pH 3.5, volatile content 2.2) manufactured by Degussa. %), “Special Black 100” (pH 3.3, volatile matter 2.2% by mass), “Special Black 250” (pH 3.1, volatile matter 2.0% by mass), “Special Black 5”. (PH 3.0, volatile content 15.0% by mass), “Special Black 4” (pH 3.0, volatile content 14.0% by mass), “Special Black 4A” (pH 3.0, volatile content 14.0) %), “Special Black 550” (pH 2.8, volatile content 2.5% by mass), “Special Black 6” (pH 2.5, volatile content 18.0% by mass), “Color Black FW2”. 0 ”(pH 2.5, volatile content 20.0% by mass),“ Color Black FW2 ”(pH 2.5, volatile content 16.5% by mass),“ Color Black FW2V ”(pH 2.5, volatile content 16) .5 mass%), “MONARCH 1000” manufactured by Cabot (pH 2.5, volatile content 9.5 mass%), “MONARCH 1300” manufactured by Cabot (pH 2.5, volatile content 9.5 mass%), manufactured by Cabot “ “MONARCH1400” (pH 2.5, volatile matter 9.0% by mass), “MOGUL-L” (pH 2.5, volatile matter 5.0% by mass), “REGAL400R” (pH 4.0, volatile matter 3.5) Mass%) and the like.
[0037]
(Addition amount of oxidized carbon black)
Oxidized carbon black as described above has better dispersibility in the resin composition due to the effect of the oxygen-containing functional group present on the surface as described above, compared to general carbon black. It is preferable to increase the amount added as. Thereby, since the amount of carbon black in the semiconductive belt increases, the effect of using the oxidized carbon black that can suppress the in-plane variation of the electrical resistance value can be maximized. .
In the present invention, by containing the oxidation-treated carbon black in an amount of 10% by mass or more and 30% by mass or less, the effect of the oxidation-treated carbon black is exhibited, such as suppressing in-plane variation in the surface resistivity of the semiconductive belt. Yes. When the content is less than 10% by mass, the uniformity of electrical resistance is lowered, and the in-plane unevenness and electric field dependency of the surface resistivity are increased. On the other hand, when it exceeds 30 mass%, it becomes difficult to obtain a desired resistance value. Further, by containing 18% by mass or more and 30% by mass or less of oxidized carbon black, the effect can be exhibited to the maximum, and the in-plane unevenness and electric field dependency of the surface resistivity can be remarkably improved. .
[0038]
<Volume resistivity>
In the case of an image forming apparatus in which the neutralization device is not provided in the secondary transfer portion, the semiconductive belt of the present invention has a volume resistivity of 1 × 10 5 for both the outer layer and inner layer polyimide resins.⁸Ωcm or more 1 × 10¹³Preferably it is Ωcm or less, 1 × 10⁹Ωcm or more 1 × 10¹²More preferably, it is Ωcm or less. This volume resistivity is 1 × 10⁸If it is less than ΩCm, the electrostatic force that holds the electric charge of the unfixed toner image transferred from the image carrier to the intermediate transfer member becomes difficult to work. The force of the fringe electric field in the vicinity may cause toner to scatter around the image (blur) and form a noisy image. Also, the volume resistivity is 1 × 10¹³If it is higher than Ωcm, the surface of the intermediate transfer member is charged by the transfer electric field in the primary transfer because the charge retention is large. In this case, high quality image quality can be stably obtained by providing a static elimination mechanism.
On the other hand, in the case of an image forming apparatus in which a static eliminator is applied to the secondary transfer portion, the volume resistivity of the inner layer and the outer layer is 1 × 10.¹³Even if the value exceeds Ωcm, the surface of the intermediate transfer member can be neutralized by a transfer electric field in primary transfer by the neutralization mechanism. The volume resistivity when the static eliminator is provided is preferably 1 × 10¹³Ωcm or more 1 × 10¹⁵Ωcm or less.
[0039]
In the semiconductive belt of the present invention, the volume resistivity can be measured according to JIS K6991 using a circular electrode (for example, HR probe of Hiresta IP manufactured by Mitsubishi Yuka Co., Ltd.). A method for measuring the volume resistivity will be described with reference to FIG. FIG. 4 is a schematic plan view (a) and a schematic cross-sectional view (b) showing an example of a circular electrode. The circular electrode shown in FIG. 4 includes a first voltage application electrode A ′ and a second voltage application electrode B ′. The first voltage application electrode A ′ has a cylindrical electrode part C ′ and a cylindrical shape having an inner diameter larger than the outer diameter of the cylindrical electrode part C ′ and surrounding the cylindrical electrode part C ′ at a constant interval. Ring-shaped electrode portion D ′. The intermediate transfer body T is sandwiched between the cylindrical electrode portion C ′ and the ring-shaped electrode portion D ′ and the second voltage application electrode B ′ in the first voltage application electrode A ′, and the circle in the first voltage application electrode A ′. The current I (A) that flows when the voltage V (V) is applied between the columnar electrode portion C ′ and the second voltage application electrode B ′ is measured, and the volume of the intermediate transfer body T is calculated by the following equation (4). The resistivity ρv (Ωcm) can be calculated. Here, in the following formula (4), t represents the thickness of the semiconductive belt T.
Formula (4) ρv = 19.6 × (V / I) × t
[0040]
The semiconductive belt of the present invention having the above-described configuration is excellent in that there is no decrease in resistance due to transfer voltage, no problem of shape deformation with time, no dependence on electric field, and little change in electrical resistance due to the environment. Have the same properties. The semiconductive belt of the present invention can be used as an intermediate transfer belt and a paper conveying belt used in an image forming apparatus such as an electrophotographic copying machine or a laser printer.
[0041]
The semiconductive belt of the present invention may contain additives other than the conductive material. Further, in addition to the outer layer and the inner layer, the number of layers can be further increased as long as the gist of the present invention is not impaired.
[0042]
The preferred range of the above physical properties is described for each layer prepared by adding an additive. The Young's modulus of the outer layer is preferably 3500 MPa or less, and more preferably 1500 MPa or more and 3500 MPa or less. By making it smaller than the Young's modulus of the inner layer, the pressing force on the transfer surface is dispersed, and image quality defects such as holocharacters can be suppressed.
On the surface of the outer layer, the surface microhardness is preferably 30 degrees or less, and more preferably 25 degrees or more and 30 degrees or less. The flatness is preferably 4 mm or less, and more preferably 2 mm or less.
On the other hand, the Young's modulus of the inner layer is preferably 4000 MPa or more, and more preferably 4000 MPa or more and 8000 MPa or less. By setting it as such a range of Young's modulus, the mechanical characteristics as a base material are satisfy | filled.
[0043]
When the belt is an endless belt, the semiconductive belt can be formed by an appropriate connection method such as an adhesive method using an adhesive at the film end or a seamless belt. it can. The seamless belt has an advantage that an arbitrary portion can be set as the rotation start position without any change in the thickness of the joint, and a control mechanism for the rotation start position can be omitted.
[0044]
Each layer is formed by, for example, a method in which the above-described polyamide solution is developed by an appropriate method, the development layer is dried to form a film, and the molded product is heat-treated to convert the polyamide into an imide. It can be carried out. Lamination of the outer layer and the inner layer is possible by repeating these operations, but a method of simultaneously converting both layers to imide after repeating the steps until conversion to imide is preferred from the viewpoint of adhesiveness of each layer.
[0045]
When forming a seamless belt, for example, an appropriate method such as a method in which a polyamide solution is immersed in the outer peripheral surface of a cylindrical mold, a method in which it is applied to the inner peripheral surface, a method in which centrifugation is further performed, or a method in which a casting mold is filled In a ring shape, the formed layer is dried and formed into a bell bowl shape, and the molded product is heat-treated to convert the polyamide into an imide and recover it from the mold as appropriate according to conventional methods. (Japanese Patent Laid-Open No. 61-95361, Japanese Patent Laid-Open No. 64-22514, Japanese Patent Laid-Open No. 3-180309, etc.). In forming the seamless belt, an appropriate treatment such as mold release treatment or defoaming treatment can be performed. In the present invention, a method in which the polyamide solution is immersed in the outer peripheral surface of the cylindrical mold is preferable.
[0046]
When forming the semiconductive belt of the present invention as a seamless belt, for example, using the raw material liquid of each layer having the components as described above, the inner layer and the outer layer are sequentially formed into a cylindrical body, and then imide conversion is performed. Just do it. The cylindrical body is formed, for example, by spreading the first layer raw material liquid on the outer peripheral surface of a cylindrical mold in the form of a cylinder by the above-mentioned coating method, forming the developed layer into a dry film, and further forming the second layer raw material. It may be developed and dried in the same manner using the liquid.
[0047]
FIG. 8 shows an apparatus for applying a polyimide raw material liquid (for example, a solution obtained by adding various additives to polyamide) used in the present invention. In FIG. 8, an aluminum mold 81 is rotated at a speed of 50 rpm to 250 rpm, and a cylindrical container (dispenser) 82 containing a polyimide raw material liquid is adjusted so as to discharge a certain amount of polyimide raw material liquid. The polyimide raw material liquid discharged to the aluminum mold 81 is made uniform by a scraper. The cylindrical container 82 and the scraper 83 are moved at a speed of 50 to 500 mm / min in the axial direction of the aluminum mold, and the polyimide layer used for the inner layer is applied to the outer peripheral surface of the aluminum mold of the cylindrical body. Form. Next, after drying at 100 ° C. to 150 ° C., a second layer polyimide raw material liquid is applied, developed, and dried. Thereafter, the temperature is raised to 360 ° C. at a rate of 2 ° C./min, and further heated at a temperature of 300 ° C. to 400 ° C. for a certain time, and the imide conversion reaction is completed by removing the solvent and removing dehydrated ring-closing water. Thereafter, the temperature is returned to room temperature, and the mold is peeled off from the mold to obtain an intended two-layered semiconductive belt.
The polyimide raw material solution has a solution viscosity at 25 ° C. in a B-type viscometer of 10 Pa · s or more and 80 Pa · s or less, preferably 15 Pa · s or more and 50 Pa · s or less. . When the viscosity of the raw material liquid is less than 10 Pa · s, only a thin film of several μm can be formed, and thus a desired film cannot be stably obtained. When it exceeds 80 Pa · s, the scraper 83 is used. There are cases where uniformization at the time of application is difficult and problems such as the occurrence of a spiral pattern occur, and the coating film cannot be formed uniformly.
In addition to polyamide and various additives, the polyimide raw material liquid contains a solvent. As the solvent, N-methyl-2-pyrrolidone is preferable. The amount of the solvent added is not particularly limited as long as the viscosity of the solution falls within the above range.
The rotational speed of the aluminum mold, the moving speed of the cylindrical container (dispenser) and the scraper have optimum ranges depending on the outer diameter of the aluminum mold, the liquid viscosity of the raw material liquid, the thickness of the film to be formed, etc. It doesn't let you.
[0048]
[Image forming apparatus]
An image forming apparatus of the present invention includes an image carrier that forms an electrostatic latent image according to image information, a developing device that visualizes the electrostatic latent image formed on the image carrier as a toner image with toner, An image forming apparatus comprising: a primary transfer unit that transfers a toner image carried on an image carrier onto an intermediate transfer member; and a secondary transfer unit that transfers a toner image on the intermediate transfer member onto a recording medium. The intermediate transfer member is the intermediate transfer member of the present invention. Since the image forming apparatus of the present invention includes the intermediate transfer body of the present invention, high-quality transfer image quality can be stably obtained.
[0049]
The present invention is not particularly limited as long as it is an intermediate transfer body type image forming apparatus. For example, a normal monocolor image forming apparatus that contains only a single color toner in a developing device, or a color image formation in which a toner image carried on an image carrier such as a photosensitive drum is sequentially subjected to primary transfer to an intermediate transfer member. The apparatus may be any of a tandem type color image forming apparatus in which a plurality of image carriers having developing units for respective colors are arranged in series on an intermediate transfer body.
[0050]
A schematic view of a color image forming apparatus using the belt-shaped intermediate transfer member of the present invention is shown in FIG. The image forming apparatus includes a photosensitive drum 1 as an image carrier, an intermediate transfer belt 2 as an intermediate transfer member, a bias roller 3 (second transfer unit) as a transfer electrode, and a sheet for supplying recording paper as a transfer medium. Tray 4, Bk (black) toner developing unit 5, Y (yellow) toner developing unit 6, M (magenta) toner developing unit 7, C (cyan) toner developing unit 8, intermediate transfer body cleaner 9, peeling Claw 13, belt rollers 21, 23 and 24, backup roller 22, conductive roller 25 (first transfer means), electrode roller 26, cleaning blade 31, recording paper 41, pickup roller 42, and feed roller 43. Become.
[0051]
In FIG. 1, the photosensitive drum 1 rotates in the direction of arrow A, and its surface is uniformly charged by a charging device (not shown). An electrostatic latent image of the first color (for example, Bk) is formed on the charged photosensitive drum 1 by image writing means such as a laser writing device. The electrostatic latent image is developed with toner by the black developing device 5 to form a visualized toner image T. The toner image T reaches the primary transfer portion where the conductive roller 25 (first transfer unit) is arranged by the rotation of the photosensitive drum 1, and an electric field having a reverse polarity is applied to the toner image T from the conductive roller 25. Thus, the toner image T is primarily transferred by the rotation of the intermediate transfer belt 2 in the direction of arrow B while being electrostatically attracted to the intermediate transfer belt 2.
[0052]
Thereafter, similarly, a second color toner image, a third color toner image, and a fourth color toner image are sequentially formed and superimposed on the intermediate transfer belt 2 to form a multiple toner image. The multiple toner image transferred to the intermediate transfer belt 2 reaches the secondary transfer portion where the bias roller 3 (second transfer means) is installed by the rotation of the intermediate transfer belt 2. The secondary transfer portion includes a bias roller 3 installed on the surface side where the toner image of the intermediate transfer belt 2 is carried, a backup roller 22 disposed so as to face the bias roller 3 from the back side of the intermediate transfer belt 2, and The electrode roller 26 is configured to rotate while being pressed against the backup roller 22.
[0053]
The recording paper 41 is picked up one by one from the recording paper bundle stored in the paper tray 4 by the pickup roller 42, and is fed between the intermediate transfer belt 2 and the bias roller 3 of the secondary transfer portion by the feed roller 43 at a predetermined timing. It is sent by. A toner image carried on the intermediate transfer belt 2 is transferred to the fed recording paper 41 by pressure contact conveyance by the bias roller 3 and the backup roller 22 and rotation of the intermediate transfer belt 2.
[0054]
The recording paper 41 onto which the toner image has been transferred is peeled from the intermediate transfer belt 2 by operating the peeling claw 13 at the retracted position until the primary transfer of the final toner image is completed, and is conveyed to a fixing device (not shown). The toner image is fixed by heat treatment to be a permanent image. The intermediate transfer belt 2 that has completed the transfer of the multiple toner images to the recording paper 41 is subjected to removal of residual toner by an intermediate transfer body cleaner 9 provided downstream of the secondary transfer portion, and is ready for the next transfer. The bias roller 3 is attached so that a cleaning blade 31 made of polyurethane or the like is always in contact therewith, and foreign matters such as toner particles and paper dust adhered by transfer are removed.
[0055]
In the case of transfer of a single color image, the primary transferred toner image T is immediately secondarily transferred and conveyed to the fixing device. In the case of transfer of a multicolor image by superimposing a plurality of colors, the toner image of each color is transferred to the primary transfer unit. Therefore, the rotation of the intermediate transfer belt 2 and the photosensitive drum 1 is synchronized so that the toner images of the respective colors do not shift so as to match exactly. In the secondary transfer section, an output pressure (transfer voltage) having the same polarity as the polarity of the toner image is applied to the electrode roller 26 that is in pressure contact with the backup roller 22 disposed so as to face the bias roller 3 and the intermediate transfer belt 2. Then, the toner image is transferred to the recording paper 41 by electrostatic repulsion.
[0056]
FIG. 2 is a schematic diagram for explaining a main part of a tandem image forming apparatus with a static eliminator. By providing the intermediate transfer belt of the present invention, a high-quality transfer image can be obtained. Specifically, in FIG. 2, a charging roller 83 (charging device) that uniformly charges the surface of the photoreceptor 79, a laser generator 78 (exposure device) that exposes the surface of the photoreceptor 79 to form an electrostatic latent image, and the photoreceptor 79 A latent image formed on the surface is developed using a developer, and a developing device 85 (developing device) for forming a toner image, and a photoconductor cleaner 84 (cleaning) for removing toner, dust and the like adhering to the photoconductor. Apparatus), a fixing roller 72 for fixing the toner image on the transfer material, and the like can be optionally provided by a known method if necessary. The charge on the intermediate transfer member 86 is neutralized by a neutralizing roller (static neutralizing unit) 88.
Even in the tandem image forming apparatus having the above-described configuration, high-quality transfer image quality can be stably obtained.
[0057]
【Example】
Examples of the present invention will be described below, but the present invention is not limited to these examples.
Example 1
(Polyamide solution for outer layer)
N-methyl-2 of polyamide which is a 1: 1 (molar ratio) reaction product of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) and 4,4′-diaminodiphenyl ether (DDE) Pyrrolidone (NMP) solution (Ube Industries' Euvanis A (solid content: 18% by mass)) was dried with oxidized carbon black (SPECIAL BLACK4 (Degussa, pH 3.0, volatile content: 14.0%) as a polyimide resin. Addition of 20 parts by mass to 100 parts by mass of solid content, using a collision type disperser (Geanus PY made by Seanas), pressure 200 MPa, minimum area 1.4 mm²Then, it was made to collide after being divided into two, and again passed through the path divided into two again, and mixed to obtain a polyamide solution (A) containing carbon black. The viscosity of the polyamide solution containing carbon black (A) was 20 Pa · s as a result of measurement with a B-type viscometer.
[0058]
(Polyamide solution for inner layer)
N-methyl-2-pyrrolidone (NMP) of polyamide which is a 1: 1 (molar ratio) reaction product of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) and p-phenylenediamine (PDA) ) A solution (Ube Industries' Euvanis S (solid content: 18% by mass)) is dried with oxidized carbon black (SPECIAL BLACK4 (Degussa, pH 3.0, volatile content: 14.0% by mass)). 23 parts by mass are added to 100 parts by mass, and a collision type disperser (GeanusPY made by Seanas) is used. The mixture was passed through and mixed to obtain a polyamide solution (B) containing carbon black. It was measured result 280 poise at a B-type viscometer.
[0059]
While rotating the polyamide solution (B) with a cylindrical aluminum mold having an outer diameter of 160 mm and a thickness of 5 mm at 100 rpm, moving the dispenser and the scraper to the outer peripheral surface at a moving speed of 150 min / min, a developing layer having a thickness of 0.3 mm Then, while rotating at 5 rpm, it was heated at 120 ° C. for 30 minutes and then cooled to room temperature. Next, the polyamide solution (A) is similarly applied to the outer peripheral surface of the obtained polyimide precursor, and then heated to 320 ° C. at a rate of 2 ° C./min, and further heated at 320 ° C. for 30 minutes. The imide conversion reaction was completed by removing the solvent and dehydrated ring-closing water. Thereafter, the temperature was returned to room temperature, and the mold was peeled from the mold to obtain the intended semiconductive belt. The thickness of this semiconductive belt was 0.08 mm, and the outer polyimide resin layer was 0.02 mm.
[0060]
(Example 2)
Combining 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) with pyromellitic dianhydride (PMDA) at a ratio of 1: 1 (mass ratio) and tetracarboxylic dianhydride did. N-methyl-2-pyrrolidone (NMP) solution of polyamide (solid content 18% by mass), which is a 1: 1 (molar ratio) reaction product of this anhydride and 4,4′-diaminodiphenyl ether (DDE), was dried. 23 parts by mass of oxidized carbon black (SPECIAL BLACK4 (manufactured by Degussa, pH 3.0, volatile content: 14.0% by mass)) is added to 100 parts by mass of polyimide resin solids, and carbon black for the outer layer A polyamide solution (C) was obtained. The viscosity of the polyamide solution (C) containing carbon black was 18 Pa · s as a result of measurement with a B-type viscometer.
The polyamide solution (B) used in Example 1 was used as the polyamide solution for the inner layer.
A semiconductive belt was obtained in the same manner as in Example 1 except that the polyamide solutions (B) and (C) were used. The thickness of this semiconductive belt was 0.1 mm, and the outer polyimimide resin layer was 0.03 mm.
[0061]
(Example 3)
3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA) are combined at a ratio of 1: 1 (mass ratio) tetracarboxylic dianhydride It was. N-methyl-2-pyrrolidone (NMP) solution of polyamide (solid content 18% by mass), which is a 1: 1 (molar ratio) reaction product of this anhydride and 4,4′-diaminodiphenyl ether (DDE), was dried. 3 parts by mass of oxidized carbon black (SPECIAL BLACK4 (Degussa, pH 3.0, volatile content: 14.0%) added to 100 parts by mass of polyimide resin solids, and a polyamide containing carbon black for the outer layer Solution (D) was obtained, and the viscosity of the polyamide solution (D) containing carbon black was 17 Pa · s as measured with a B-type viscometer.
As the polyamide solution for the inner layer, the same polyimide acid solution (B) containing carbon black as in Example 1 was used.
A semiconductive belt was obtained in the same manner as in Example 1 except that the polyamide solutions (B) and (D) were used. The thickness of the semiconductive belt was 0.1 mm, and the outer polyimimide resin layer was 0.01 mm.
[0062]
(Comparative Example 1)
Using only the polyamide solution containing carbon black (A), while rotating a cylindrical aluminum mold having an outer diameter of 160 mm and a thickness of 5 mm at 100 rpm, moving the dispenser and the scraper to the outer peripheral surface at a moving speed of 150 min / min, After forming a development layer having a thickness of 0.2 mm, it was heated at 120 ° C. for 30 minutes while being rotated at 5 rpm, and then cooled to room temperature. Thereafter, the temperature was raised to 320 ° C. at a rate of 2 ° C./min, and further heated at 320 ° C. for 30 minutes, and the imide conversion reaction was completed by removing the solvent and removing dehydrated ring-closing water. Thereafter, the temperature was returned to room temperature.
In this case, peeling from the mold was very difficult. It has been peeled off by spraying moisture on the polyimide belt and expanding the polyimide belt. The thickness of this semiconductive belt was 0.05 mm.
[0063]
(Comparative Example 2)
The inner layer polyamide solution (B) of Example 1 was used as the outer layer polyamide solution.
The molar ratio of p-phenylenediamine (PDA) and 4,4′-diaminodiphenyl ether (DDE) with PDA / DDE = 8: 2 was used as the diamine component, and 3,3 ′, 4,4′-biphenyl. Polyamide N-methyl-2-pyrrolidone (NMP) solution (solid content 18% by mass) reacted with tetracarboxylic dianhydride (BPDA) at a molar ratio of 1: 1 was dried carbon black (acetylene black ( Density Chemical Industries, Ltd. (pH 5.7, volatile content: 0.89% by mass) was added in an amount of 13 parts by mass with respect to 100 parts by mass of the polyimide resin solid content to obtain a carbon black-dispersed polyamide solution (E) for the inner layer. The viscosity of the polyamide solution (E) was 4 Pa · s as measured with a B-type viscometer.
[0064]
The polyamide solution containing carbon black (B) is applied to the inner surface of the cylindrical mold to 0.5 mm via a dispenser, rotated at 1500 rpm for 15 minutes to form a spread layer having a uniform thickness, and then rotated at 250 rpm. A hot air of 60 ° C. was applied for 30 minutes from the outside of the mold, heated at 150 ° C. for 60 minutes, and then cooled to room temperature. Next, on the inner surface of the carbon black-dispersed polyimide precursor obtained in this state, the polyamide solution containing carbon black (E) was applied in the same manner, and then heated to 360 ° C. at a rate of 2 ° C./min. Furthermore, the imide conversion reaction was completed by heating at 360 ° C. for 30 minutes to remove the solvent and dehydrated ring-closing water. Thereafter, the temperature was returned to room temperature, and the mold was peeled from the mold to obtain the intended semiconductive belt. The thickness of this semiconductive belt was 0.08 mm, and the outer polyimide resin layer was 0.02 mm.
[0065]
<Evaluation>
For the semiconductive belts obtained in Examples 1, 2, and 3 and Comparative Examples 1 and 2, the flatness, the surface microhardness of the transfer surface, the volume resistivity, and the transfer image quality (blur, holo character, color register), evaluated.
[0066]
(Measurement of flatness)
As shown in FIG. 7, the flatness in the present invention is such that a semiconductive belt is stretched by applying a load of 4 kg on two parallel shafts 18 (Φ28 mm), and the surface of the semiconductive belt at that time is laser-displaced. The maximum value and the minimum value of the displacement amount of the belt surface are measured by the laser displacement meter 17 with the central portion of the shaft paired with the shaft stretched by a total of 17 (Keyence Corporation LK-030) parallel to the axis. The difference is read.
Judgment was evaluated according to the following criteria.
○: Flatness 4mm or less
×: When the flatness exceeds 4 mm
[0067]
FIG. 5 is a schematic cross-sectional view showing the measurement principle of the surface microhardness of the surface layer. In FIG. 5, 50 represents the surface layer, 51 represents the needle-shaped indenter, and arrow L represents the load applied to the needle-shaped indenter 51. Means.
In measuring the surface microhardness, the tip of the needle-shaped indenter 51 having a predetermined shape is pressed onto the outermost surface portion of the surface layer 51 until the load L (mN) is changed from the load 0 to the predetermined load P. When the biting depth in the vertical direction into the surface layer 50 of the needle-shaped indenter 51 at this time is D (μm), the surface microhardness DH is expressed by the following formula (1).
Formula (1) DH = α · P / D
In equation (2), α means a coefficient determined in advance by the shape of the needle-like indenter 51, measurement conditions, etc., P means a predetermined load (mN), and D means a surface layer of the needle-like indenter 51. This means the depth of penetration (μm) in the vertical direction into 50.
[0068]
<Volume resistivity>
As described above, the volume resistivity is measured using a circular electrode (HIROSTER IP HR probe manufactured by Mitsubishi Yuka Co., Ltd.) and the cylindrical electrode portion C ′ and the second voltage in the first voltage application electrode A ′. A voltage of 100 (V) was applied between the electrode B ′ and the current value after 30 seconds.
[0069]
<Evaluation of image quality (holo character)>
Each semiconductive belt obtained above was attached to a color image forming apparatus (Color Laser Wind modified machine manufactured by Fuji Xerox), image formation was performed, and image quality (holocharacter) was evaluated according to the following criteria. (In the case of Example 3, the image quality was evaluated by partially modifying and applying a static eliminator).
◎: No holo character
○: Slight occurrence of holo-characters, but no problem in image quality
×: There is a generation of holo characters, there is a problem in image quality
[0070]
<Evaluation of cash register misalignment>
Each semiconductive belt obtained as described above was attached to a color image forming apparatus (Color Laser Wind remodeling machine manufactured by Fuji Xerox), image formation was performed, and image quality (color registration) was evaluated according to the following criteria.
○: The registration error is 0.08 mm or less, and there is no problem in image quality.
×: The registration error is 0.08 mm or more, and there is a problem in image quality
[0071]
<Comprehensive evaluation>
○: Practical
×: Practical problem
[0072]
These results are shown in Table 1 below.
[Table 1]

[0073]
From the results in Table 1, the semiconductive belts of Examples 1 to 3 of the present invention have excellent flatness and the surface hardness of the transfer surface is small. I was able to obtain it stably. On the other hand, Comparative Example 1 has a problem of misregistration. When a polyimide belt is molded by the method of the present invention, there is a problem in releasability from the mold. It was necessary to improve. In Comparative Example 2, the flatness was poor, and the surface microhardness of the transfer surface was as hard as 40, so there was a problem with the holocharacter.
[0074]
【The invention's effect】
According to the present invention, it is possible to inexpensively manufacture a semiconductive belt that is excellent in flatness and can obtain a high quality without holocharacter, blur, and misregistration, and includes the semiconductive belt, An image forming apparatus capable of stably obtaining a high-quality transfer image quality can be provided.
[0075]
[Brief description of the drawings]
FIG. 1 is a schematic view showing a color image forming apparatus using a belt-shaped intermediate transfer member of the present invention.
FIG. 2 is a schematic view showing a color image forming apparatus using the belt-shaped intermediate transfer member of the present invention.
FIG. 3 is a cross-sectional view showing a belt configuration of the present invention.
FIG. 4 is a diagram illustrating a method for measuring volume resistivity.
FIG. 5 is a schematic diagram showing the principle of measuring the surface microhardness of the surface layer.
FIG. 6 is a diagram showing the relationship between the circumference of a polyimide belt and the outer diameter of a metal core (mold).
FIG. 7 is a schematic configuration diagram of an apparatus for measuring the flatness of a belt.
FIG. 8 is a schematic configuration diagram of an apparatus for applying a polyimide liquid used in the present invention.
[Explanation of symbols]
1 Photosensitive drum (image carrier)
2 Intermediate transfer belt (intermediate transfer member)
3 Bias roller (second transfer means)
4 Paper tray
5 Black developer
6 Yellow developer
7 Magenta developer
8 Cyan developer
9 Intermediate transfer body cleaner
10 Transfer roller
13 Peeling nails
14 Conveyor belt
16 Photoconductor cleaner
21 Belt roller
22 Backup roller
23 Belt roller
24 belt roller
25 Conductive roller (first transfer means)
26 Electrode roller
30 Intermediate transfer drum
31 Cleaning blade
41 Recording paper
42 Pickup roller
43 Feed Roller
71 toner cartridge
72 Fixing roller
73 Backup Roller
74 Tension roller
75 Secondary transfer roller
76 Paper path
77 Paper tray
78 Laser generator
79 photoconductor
80 Primary transfer roller
81 Drive roller
82 Transcription Cleaner
83 Charging roller
84 Photoconductor cleaner
85 Developer
86 Intermediate transfer member
88 Static elimination roller
T Toner image

Claims (8)

An endless belt used in an electrophotographic image forming apparatus,
The endless belt has an outer layer (a) and an inner layer (b);
The outer layer (a) and the inner layer (b) are both mainly composed of a polyimide resin,
The linear expansion coefficient at 10 to 250 ° C. of the inner layer (b) is smaller than the linear expansion coefficient of the mold metal used for producing the endless belt,
A semiconductive belt, wherein the outer layer (a) has a larger linear expansion coefficient than the inner layer (b). An endless belt used in an electrophotographic image forming apparatus,
The endless belt has an outer layer (a) and an inner layer (b);
The outer layer (a) and the inner layer (b) are both mainly composed of a polyimide resin,
The linear expansion coefficient at 10 to 250 ° C. of the inner layer (b) is 23 ppm / ° C. or less,
A semiconductive belt, wherein the outer layer (a) has a larger linear expansion coefficient than the inner layer (b). The linear expansion coefficient at 10 ° C to 250 ° C is such that the difference between the outer layer (a) and the inner layer (b) is 50 ppm / ° C or less, and the linear expansion coefficient of the outer layer is larger than that of the inner layer. The semiconductive belt according to claim 1 or 2. The ratio of the thickness of the said outer layer (a) is 10 to 50% of the total thickness of a belt, The semiconductive belt in any one of Claims 1-3 characterized by the above-mentioned. The semiconductive belt according to any one of claims 1 to 4, wherein a diamine which is a raw material of the polyimide resin of the inner layer (b) contains p-phenylenediamine as a main component. The semiconductive belt according to any one of claims 1 to 5, wherein a diamine which is a raw material of the polyimide resin of the outer layer (a) contains 4,4'-diaminophenyl ether as a main component. It is a manufacturing method of the semiconductive belt in any one of Claims 1-6, Comprising: The polyamide solution for forming an inner layer (b) is apply | coated to the outer peripheral surface of a metal core, Endless belt-like polyimide A system precursor is formed, and then a polyamide solution for forming the outer layer (a) is applied to form an endless belt-like polyimide precursor to form an endless belt, and then the endless belt A method for producing a semiconductive belt, which is cured by heating. The polyamide solution for forming the inner layer (b) and the polyamide solution for forming the outer layer (a) both have a solution viscosity at 25 ° C. in a B-type viscometer of 10 Pa · s to 80 Pa · s. The method of manufacturing a semiconductive belt according to claim 7, wherein the method is within a range.

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