JP2006098602A - Conductive seamless belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive seamless belt capable of preventing cracking and not causing image defects such as color smear by improving the bending fatigue resistance and elastic modulus of a belt, improvement of which is required, while using a polyether sulfone and taking advantage of its properties such as flame resistance. <P>SOLUTION: In the conductive seamless belt, a polyether sulfone, a liquid crystal polymer and a conductive filler are blended and the polyether sulfone and the liquid crystal polymer are in the form of a polymer alloy. It is preferable that, in the belt, the polyether sulfone and the liquid crystal polymer are blended in a weight ratio of 95:5 to 50:50 and the conductive filler is blended in a proportion of 1-50 pts. wt. to 100 pts. wt., in total of, the polyether sulfone and the liquid crystal polymer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a conductive seamless belt used for an image forming apparatus using an electrophotographic system such as an electrophotographic copying machine, a laser printer, a facsimile, and a composite apparatus thereof, and more particularly a conductive seamless belt that can be suitably used for a color image forming apparatus. About.

  An image forming apparatus using an electrophotographic system forms a uniform charge on a photoconductor composed of an inorganic or organic conductive material, and forms an electrostatic latent image on the photoconductor with writing light from an exposure unit. Thereafter, the electrostatic latent image is developed with toner from the developing unit to form a toner image on the photoreceptor. Next, the toner image formed on the photosensitive member is transferred to the intermediate transfer member. In the case of mono-color, this operation is performed once. In the case of full-color image formation, a multicolor image other than full-color is formed four times with yellow (Y), magenta (M), cyan (C), and black (K). In this case, the number of times corresponding to the two or three toner colors to be used is repeated, and the toner formed after primary transfer to the intermediate transfer member (so that the toner images are sequentially superimposed in the case of a multicolor image) The images are collectively transferred to a recording medium such as paper. Finally, the toner image transferred to the recording medium is fixed on the recording medium by the fixing unit and output. In addition to the cycle type apparatus as described above, the color image forming apparatus includes a tandem type in which a plurality of image carriers on which toner images of different colors are formed are arranged in series on an intermediate transfer body. There is a color image forming apparatus.

  As a seamless belt used as an intermediate transfer member or the like of such an image forming apparatus, it is necessary to play a role of accurately superimposing toner of 2 to 4 colors on the belt so that accurate rotation performance can be obtained. In order to achieve this, the dimensional stability of the belt is required.

  By the way, in recent years, high image quality similar to that of inkjet has been demanded in the field of color printers, etc., and a seamless belt made of polyethersulfone as a belt that satisfies the requirement of dimensional stability for such high image quality. However, this belt has a high initial elastic modulus, and even when the tensioned state continues, the decrease from the initial elastic modulus is small and the elongation is small. It is said that it is hard to generate | occur | produce (for example, refer patent document 1). In addition, the use of polyethersulfone matches the trend of the industry that requires flameproofing of OA equipment because polyethersulfone itself has flame retardancy.

  However, when polyethersulfone is used as a seamless belt, there is a problem in that it is inferior in durability due to inferior resistance to bending fatigue and cracks and the like. In addition, this polyethersulfone belt has a relatively high initial elastic modulus and a small decrease from the initial elastic modulus even if the tensioned state continues, but it aims to achieve higher durability and higher image quality. Therefore, further improvement in bending fatigue and high elastic modulus are required.

In addition, as a conductive seamless belt used in an image forming apparatus using an electrophotographic method, a certain range of volume resistivity (conductivity) is required. For example, considering use as a photoreceptor belt, 10 to 10 ⁵ Ω · cm is used to facilitate the flow of electrons, 10 ⁵ to 10 ¹² Ω · cm is used as an intermediate transfer belt, and 10 ¹⁰ to 10 ¹⁵ is used as a transfer transfer belt. A range of Ω · cm is preferred (see, for example, Patent Document 2).
JP-A-11-115066 (paragraphs 0004, 0005, 0031). JP-A-11-115066 (paragraph 0009).

  Therefore, the present invention can prevent the occurrence of cracks by improving the flexural fatigue resistance and elastic modulus of the belt that is required to be improved while utilizing the properties such as flame retardancy using polyethersulfone, Another object of the present invention is to provide a seamless belt that does not cause image quality defects such as color misregistration.

  As a result of diligent research to achieve the above objectives, bending fatigue resistance and elastic modulus have been improved by polymer alloying of amorphous sulfone polyethersulfone and crystalline resin liquid crystal polymer and blending of conductive fillers. The present inventors have found that a seamless belt that can solve the problems of crack generation and image quality defects can be obtained.

  That is, according to the first aspect of the present invention, polyethersulfone (hereinafter referred to as PES), a liquid crystal polymer, and a conductive filler are blended, and the PES and the liquid crystal polymer are polymer-alloyed. It is an electroconductive seamless belt characterized by these.

  The liquid crystal polymer used in the present invention is not particularly limited as long as it is a so-called liquid crystal polymer exhibiting optical anisotropy in a melt phase or a solution phase. That is, the liquid crystal polymer includes both a so-called thermotropic liquid crystal polymer and a lyotropic liquid crystal polymer, but it is preferable to use a thermotropic liquid crystal polymer. This is because the conductive belt of the present invention can be easily manufactured using melt molding such as extrusion.

  In addition, the conductive filler is not particularly limited as long as it is a filler that can be used to impart conductivity to the belt, but a metal or alloy such as carbon black, graphite, aluminum, copper, iron, nickel, a copper alloy, Alternatively, fine powders of metal oxides such as tin oxide, zinc oxide, titanium oxide, tin oxide-indium oxide or tin oxide-antimony oxide composite oxide are exemplified. These metals, alloys or metal oxides can be used alone or in admixture of two or more. Among them, it is preferable to use carbon black because it is inexpensive and versatile.

  The polymer alloy as used in the present invention is used in a broad sense, and it is a narrowly-defined polymer in a blend of different types of polymers (a state in which they are uniformly mixed without causing phase separation (completely compatible state and / or interfacial affinity phase separated state)). It includes not only alloys but also blends in an incompatible phase separation state), block copolymers and graft copolymers of different polymers, and an interpenetrating polymer network (IPN) in which different polymers are intertwined in a network.

  Of the present invention, the second invention is characterized in that the PES and the liquid crystal polymer are blended in a weight ratio of 95/5 to 50/50. Is the default.

  The PES and the liquid crystal polymer are used in a weight ratio of 95/5 to 50/50 because if the PES exceeds 95/5, cracks or the like are likely to occur in the seamless belt. The image obtained when used in an image forming apparatus is improved against image quality defects such as color misregistration caused by using a PES single seamless belt (hereinafter referred to as “PES single seamless belt”) in which no liquid crystal polymer exists. This is because an image obtained when this belt is used in an image forming apparatus tends to deteriorate the image quality itself. This is because when the PES exceeds 95/5, the bending fatigue resistance and the elastic modulus of the belt are insufficiently improved by the liquid crystal polymer, and when it is less than 50/50, the dispersibility of the conductive filler is hindered by the liquid crystal polymer. It is thought that.

  Of the present invention, the third invention is characterized in that the blending amount of the conductive filler is 1 to 50 parts by weight with respect to 100 parts by weight of the total amount of the PES and the liquid crystal polymer. Or it is an electroconductive seamless belt of 2nd invention description.

  The conductive filler is used in an amount of 1 part by weight to 50 parts by weight with respect to 100 parts by weight of the total amount of the PES and the liquid crystal polymer. If it exceeds, the dispersion of the conductive filler into the seamless belt will be hindered and the mechanical properties will be extremely lowered. This is because the toner does not occur and causes a toner transfer failure, so that a high quality image may not be formed.

  1. The seamless belt of the first invention has improved bending fatigue resistance and elastic modulus as compared with the PES single seamless belt by alloying PES and liquid crystal polymer. As a result, the problem of crack generation is improved by improving the bending fatigue resistance, and further, when this belt is used in an image forming apparatus by improving the elastic modulus, color misregistration or the like that occurs when a PES single seamless belt is used. The problem of image quality defects can also be improved or eliminated.

  2. In addition, the seamless belt of the second invention is such that PES and liquid crystal polymer are used in a ratio of 95/5 to 50/50 by weight ratio, so that cracks and the like hardly occur in the seamless belt. The image obtained in the case of using the image forming apparatus improves image quality defects such as color misregistration that occur when the PES single seamless belt is used, and does not generate such image quality defects. Moreover, the seamless belt having this blending ratio is maintained as it is without impairing the flame retardancy of PES.

  3. Furthermore, the seamless belt of the third invention has been found out of an appropriate blending amount of the conductive filler to the polymer alloyed PES and the liquid crystal polymer, and the blending amount of the conductive filler is the sum of the PES and the liquid crystal polymer. When used at a ratio of 1 part by weight to 50 parts by weight with respect to 100 parts by weight, the resulting image is of higher quality than when used at a ratio outside this range.

  Hereinafter, the best mode for carrying out the present invention will be described, but the present invention is not limited to these modes. The seamless belt according to the present invention is manufactured as follows.

(Kneading of ingredients)
PES, for example, the following liquid crystal polymer and, for example, carbon black, are kneaded as necessary components using a kneader such as a single screw extruder, a twin screw extruder, a Banbury mixer, a roll, or a kneader. In this case, the PES and the liquid crystal polymer are preferably used in a weight ratio of 95/5 to 50/50, and the blending amount of carbon black is 100 parts by weight of the total amount of the PES and the liquid crystal polymer. The amount is preferably 1 part by weight to 50 parts by weight. As an additional component, various organic and inorganic additives such as polymers other than the above, extenders, various pigments, ultraviolet absorbers, antistatic agents, dispersants, neutralizing agents and the like can be blended. It is.

(Liquid crystal polymer)
It is preferable to use a thermotropic liquid crystal polymer having an aromatic polyester as the main chain. Commercial products of such liquid crystal polymers include VICTREX SRP (manufactured by ICC Japan), UENO LCP (manufactured by Ueno Pharmaceutical), VECTRA (manufactured by Polyplastics), and Novacurate E234 (Mitsubishi Kasei) Product), Idemitsu LCP200 (manufactured by Idemitsu Petrochemical Co., Ltd.), rod run LC-5000 (manufactured by Unitika Ltd.) and the like.

(Seamless belt molding)
The kneaded product obtained by the kneading can be molded using a known method such as a continuous melt extrusion molding method, an injection molding method, a blow molding method, or an inflation molding method to obtain a seamless belt according to the present invention. it can.

  The seamless belt of the polymer component as described above is easily melt-molded, and it is considered that PES and thermotropic liquid crystal polymer are made into a polymer alloy in a narrow sense. As a result of the significant increase in the rate, the problem of crack generation with respect to the single seam level of PES is greatly improved, and the problem of image quality defects such as color misregistration recognized in the seamless belt of PES alone does not occur. In particular, a seamless belt having a blending ratio (weight ratio) of PES and liquid crystal polymer of 95/5 to 50/50 maintains the same level of flame retardancy as that of a PES single seamless belt.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely using an Example, this invention is not limited to these Examples.

Example 1
PES (trade name: Sumika Excel PES 4100P, manufactured by Sumitomo Chemical Co., Ltd.) and liquid crystal polymer (trade name: Rodrun LC-5000, manufactured by Unitika) were blended at a ratio of 90 parts by weight for the former and 10 parts by weight for the latter. A blend of 20 parts by weight of carbon black with respect to 100 parts by weight of the resin component was supplied to an extruder and melt-kneaded to produce thermoplastic resin pellets having a volume resistivity of 5 × 10 ¹⁰ Ω · cm. The pellets were extruded in the form of a molten tube below the annular die with an extruder equipped with an annular die and cut into round pieces to obtain a conductive seamless belt having a diameter of 150 mm, a length of 266 mm, and a thickness of 150 μm.

(Example 2)
PES (trade name: Sumika Excel PES 4100P, manufactured by Sumitomo Chemical Co., Ltd.) and liquid crystal polymer (trade name: Rodrun LC-5000, manufactured by Unitika) were blended in a ratio of 70 parts by weight for the former and 30 parts by weight for the latter. A blend of 20 parts by weight of carbon black with respect to 100 parts by weight of the resin component was supplied to an extruder and melt-kneaded to prepare thermoplastic resin pellets having a volume resistivity of 3 × 10 ¹⁰ Ω · cm. The pellets were extruded in the form of a molten tube below the annular die with an extruder equipped with an annular die and cut into round pieces to obtain a conductive seamless belt having a diameter of 150 mm, a length of 266 mm, and a thickness of 150 μm.

(Comparative Example 1)
Using only PES (trade name: SUMIKAEXCEL PES 4100P, manufactured by Sumitomo Chemical Co., Ltd.) as a resin component, a mixture of 20 parts by weight of carbon black with respect to 100 parts by weight is supplied to an extruder, melt-kneaded, and A thermoplastic resin pellet having a volume resistivity of 7 × 10 ¹⁰ Ω · cm was produced. The pellets were extruded in the form of a molten tube below the annular die with an extruder equipped with an annular die and cut into round pieces to obtain a conductive seamless belt having a diameter of 150 mm, a length of 266 mm, and a thickness of 150 μm.

(Comparative Example 2)
Using only liquid crystal polymer (trade name: Rod Run LC-5000, manufactured by Unitika) as a resin component, a blend of 20 parts by weight of carbon black with respect to 100 parts by weight is supplied to an extruder, melt-kneaded, and volume A thermoplastic resin pellet having a resistivity of 9 × 10 ¹⁰ Ω · cm was produced. The pellets were extruded in the form of a molten tube below the annular die with an extruder equipped with an annular die and cut into round pieces to obtain a conductive seamless belt having a diameter of 150 mm, a length of 266 mm, and a thickness of 150 μm.

(Elastic modulus evaluation test)
The elastic modulus of the seamless belts of Examples 1 and 2 and Comparative Examples 1 and 2 was measured according to JIS K 7127. That is, measurement was performed at a test speed of 50 mm / min using a 10 mm × 150 mm strip test piece. The volume resistivity of these belts was determined by reading the current value 10 seconds after applying a voltage of 100 V using a resistance meter (HR probe from Hiresta IP: manufactured by Dia Instruments).

(Bending fatigue resistance evaluation test)
For the seamless belts of Examples 1 and 2 and Comparative Examples 1 and 2, respectively, JIS P
In accordance with 8115, the number of bending resistances (times) was evaluated.

(Image quality (color shift) evaluation test)
A color printer (LP-3000C, manufactured by Epson) was equipped with the seamless belts of Examples 1 and 2 and Comparative Examples 1 and 2, respectively, and an image formation test was performed. The obtained copy image was observed with a magnifying lens. Color misregistration (that is, toner positional deviation) and image quality were visually evaluated according to the following criteria.
◎ There is no toner misalignment and the image quality is very good.
○ There is almost no toner misalignment and the image quality is relatively good.
Δ Some toner misalignment is observed, and the image quality is slightly inferior.
X Toner misalignment is noticeable and image quality is poor.

(Flame retardancy evaluation test)
The seamless belts of Examples 1 and 2 and Comparative Examples 1 and 2 were evaluated for flame retardancy according to the UL94 thin material vertical combustion test.

  About the seamless belts of Examples 1 and 2 and Comparative Examples 1 and 2, the evaluation results of the elastic modulus, bending fatigue resistance, image quality and flame retardancy of these belts were respectively performed as described above. These are summarized in Table 1.

実施例１，２のシームレスベルトは、表１に示すように比較例１のＰＥＳ単独のシームレスベルトに比べ、弾性率が大幅に向上している。その結果、実施例１，２のシームレスベルトは、駆動時の応力に対するベルトの変形がＰＥＳ単独シームレスベルトより小さくなり、表１に示すように色ずれ等の画質欠陥を生じることなく、高画質を生み出すと考えられる。また、実施例１，２のシームレスベルトはＰＥＳと結晶性の液晶ポリマーが狭義のポリマーアロイ化していると考えられ、非晶性のＰＥＳのみの比較例１に比べ、耐屈曲疲労性も大きく改善されている。

As shown in Table 1, the seamless belts of Examples 1 and 2 have significantly improved elastic modulus as compared with the seamless belt of PES alone of Comparative Example 1. As a result, in the seamless belts of Examples 1 and 2, the deformation of the belt with respect to the stress at the time of driving is smaller than that of the PES single seamless belt, and as shown in Table 1, high image quality is achieved without causing image quality defects such as color misregistration. It is thought to produce. In addition, the seamless belts of Examples 1 and 2 are considered to be a polymer alloy in which PES and crystalline liquid crystal polymer are narrowly defined, and the bending fatigue resistance is greatly improved as compared with Comparative Example 1 in which only amorphous PES is used. Has been.

  On the other hand, in Comparative Example 2, since the liquid crystal polymer is crystalline, the bending fatigue resistance and the elastic modulus are excellent, but the image quality itself is deteriorated. This is considered to be caused by non-uniformity of toner transfer due to non-uniform dispersion of carbon black rather than color shift due to a very high elastic modulus.

  In addition, the seamless belts of Examples 1 and 2 are equivalent to the PES single seamless belt of Comparative Example 1 in the flame retardancy evaluation, and the flame retardancy of PES is maintained as it is. This result shows that, as shown in Comparative Example 2, if a seamless belt made of a liquid crystal polymer alone is inferior in flame retardancy evaluation, the flame retardancy of PES can be improved by using a polymer alloyed belt of liquid crystal polymer and PES. It is clarified that it can be maintained as it is.

Claims (3)

A conductive seamless belt comprising a polyether sulfone, a liquid crystal polymer, and a conductive filler, wherein the polyether sulfone and the liquid crystal polymer are polymer-alloyed. The conductive belt according to claim 1, wherein the polyether sulfone and the liquid crystal polymer are blended in a weight ratio of 95/5 to 50/50. The conductive amount according to claim 1 or 2, wherein the amount of the conductive filler is 1 to 50 parts by weight with respect to 100 parts by weight of the total amount of the polyethersulfone and the liquid crystal polymer. Seamless belt.