JP2006182813A - Electroconductive seamless belt, manufacturing method of electroconductive seamless belt, and image-forming apparatus equipped with electroconductive seamless belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electroconductive seamless belt capable of decreasing volume resistivity, while maintaining a certain rigidity, down to a level which has been unattainable at the rigidity. <P>SOLUTION: The electroconductive seamless belt is obtained by molding a thermoplastic composition, which comprises 100 pts.wt. of a polymer component, mainly composed of a blend comprising at least a first polyester thermoplastic elastomer having a specified hardness and a second polyester thermoplastic elastomer having a lower hardness than the first polyester thermoplastic elastomer, and 0.01-3 pts.wt. of a salt having a specified anion, the content of the second polyester thermoplastic elastomer in the whole polymer component being smaller than that of the first polyester thermoplastic elastomer and at most 30 wt.%, and has volume resistivity of 1.0×10<SP>6</SP>to 1.0×10<SP>10</SP>Ωcm. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a conductive seamless belt, a method for manufacturing a conductive seamless belt, and an image forming apparatus including the conductive seamless belt. Specifically, the compounding material used to form seamless belts used in image forming apparatuses that perform image formation by electrophotography or electrostatic printing, such as copying machines, facsimiles, and printers, has been improved to provide sufficient rigidity and conductivity for seamless belts. In addition to imparting properties, the variation in electric resistance value in the belt surface is reduced, and stable and good image formation is realized.

An image forming apparatus that forms an image by an electrophotographic method or an electrostatic printing method, such as a copying machine, a facsimile, a printer, etc., a conveyance belt, a transfer belt, an intermediate transfer belt, a fixing belt, a developing belt, a photoreceptor substrate belt, etc. As a conductive seamless belt.
Such a conductive seamless belt needs to have an appropriate and stable volume resistivity. As a method for imparting conductivity to the seamless belt, an electron conductive material such as a metal oxide or carbon black is blended with a polymer material, and an ion conductive material is blended with the polymer material. And a method for imparting ionic conductivity.

  For example, carbon black as an electronic conductive material is mixed in a thermosetting resin such as polyimide, and a seamless belt obtained by centrifugal molding, or a thermoplastic resin such as polycarbonate or polyvinylidene fluoride, or carbon as an electronic conductive material. A seamless belt obtained by kneading black or metal oxide and extruding is known.

  However, when an electronic conductive material is used, the volume resistivity becomes unstable due to the dispersion state of the material particles. In particular, if an agglomerate of an electronic conductive material is present, current flows intensively in that portion, so it is difficult to control the resistance value of the belt. In addition, when the blending amount of the electronic conductive material is increased, the belt tends to become brittle, and the belt blended with carbon black has a black color, which makes it difficult to visually check the contamination state due to toner or the like.

In addition, a seamless belt obtained by molding polyimide or polycarbonate has a problem in durability because the belt is easily torn, such as cracking from the end of the belt when the belt is stretched continuously around the drive shaft. And when using a thermosetting resin as a polymer material, since a thermosetting process is needed separately from centrifugal molding and the casting to a metal mold | die, there exists a problem that an effort and cost start.
On the other hand, when a fluorine-containing polymer such as polyvinylidene fluoride is used, a corrosive gas may be generated during extrusion molding, so a molding machine with special processing is required, which is disadvantageous in terms of manufacturing cost. Become.
Furthermore, a seamless belt obtained by molding an olefin-based material such as polyethylene or polypropylene is inferior in creep characteristics and has a permanent elongation, and therefore cannot withstand continuous use.

  In JP-A-2002-304064 (Patent Document 1), a resin composition comprising at least one thermoplastic resin and at least one hydrophilic resin that is incompatible with the thermoplastic resin. There has been proposed an endless belt (seamless belt) obtained by extrusion molding, wherein the viscosity of the thermoplastic resin at the molding temperature at the time of extrusion molding is higher than the viscosity of the hydrophilic resin. This proposal aims to achieve uniform and sufficient resistance control in a seamless belt.

  In Japanese Patent No. 3315933 (Patent Document 2), in a seamless belt, a loss tangent (tan δ) obtained by dispersing a conductive filler in a polyester polyether resin having a melting point in the range of 160 to 210 ° C. is 0.1 to 0. It has been proposed to use a conductive base layer in the range of two. This proposal is intended to realize a seamless belt that has moderate flexibility in the thickness direction and does not stretch in the length direction even when used continuously over a long period of time.

JP 2002-304064 A Japanese Patent No. 3315933

In the conductive seamless belt, as described in Patent Document 1, uniform and sufficient resistance control is performed, and as described in Patent Document 2, in the continuous use for a long time, in the length direction. It is important to make it difficult to stretch.
However, if a certain rigidity is imparted to the seamless belt in order to make it difficult to extend in the length direction, there is a limit to the reduction in volume resistivity, and it becomes difficult to achieve a volume resistivity below a certain value. As a result, the use of the seamless belt is also limited.
Specifically, when an ion conductive salt is blended with a polymer component mainly composed of a polyester-based thermoplastic elastomer to obtain a transfer belt having a desired resistance value, Concerns arise.

First, if priority is given to belt rigidity and emphasis is placed on preventing color shift during transfer, ASTM
It is necessary to use a polyester-based thermoplastic elastomer having a D-type hardness of 65 or more measured in accordance with D2240. In this case, the volume resistivity of the belt cannot be reduced to 1.0 × 10 ¹⁰ Ω · cm or less even if the ion conductive salt is added excessively. If an excessive amount of salt is added, the processability of the material becomes poor, and salt oozes out of the belt.
Therefore, a seamless belt having a volume resistivity of 1.0 × 10 ¹⁰ Ω · cm or less is usually obtained simply by blending an ion conductive salt with a polyester thermoplastic elastomer having a D type hardness of 65 or more. Can not. This is because a polyester-based thermoplastic elastomer having a high hardness has a large composition ratio of hard segments, so that a conductive mechanism by an ion conductive material is not sufficiently developed.
However, in the case of an intermediate transfer belt, unless the volume resistivity is lowered to 1.0 × 10 ¹⁰ Ω · cm or less, the transfer voltage required to copy the charged toner from the photosensitive member becomes high, and the transfer efficiency is low. Turn into.

Second, when using a polyester-based thermoplastic elastomer having a D-type hardness of 55 or more and less than 65 measured in accordance with ASTM D2240, the volume resistivity can be reduced to about 1.0 × 10 ⁸ Ω · cm. However, it is generally difficult to achieve volume resistivity below that. Further, if the volume resistivity can be lowered to about 1.0 × 10 ⁸ Ω · cm, a sufficient transfer performance can be obtained in some image forming apparatuses, but the rigidity of the belt is reduced, and the transfer at the time of transfer is reduced. There is concern about color shift.
However, a volume resistivity of 1.0 × 10 ^{6 to} 1.0 × 10 ⁸ Ω · cm may be required from the viewpoint of reducing transfer voltage and improving transfer efficiency. For example, in order to improve transferability through primary transfer in which toner is transferred from a photoreceptor to an intermediate transfer belt and secondary transfer in which toner is transferred from the intermediate transfer belt to a recording medium such as paper, the volume resistance is further reduced by 1 to 2 digits. A rate is required. In such a case, a material in which an ion conductive salt is excessively mixed cannot be used.

Third, when using a polyester-based thermoplastic elastomer having a D-type hardness of less than 50 as measured in accordance with ASTM D2240, up to 1.0 × 10 ⁶ Ω · cm, the workability is not impaired, and the salt Volume resistivity can be reduced within a range that does not cause bleeding. However, such a belt has insufficient rigidity to be used as an intermediate transfer belt, and the belt is stretched due to the tension at the time of driving the belt, which causes image misalignment.

  Accordingly, an object of the present invention is to provide a conductive seamless belt capable of reducing the volume resistivity to a level that could not be achieved with the rigidity while maintaining a certain rigidity. Another object of the present invention is to provide a conductive seamless belt with suitable physical properties according to the application and to realize good image formation.

The present invention relates to an electrically conductive seamless belt formed by molding a thermoplastic composition, and the thermoplastic composition comprises 100 parts by weight of a polymer component and 0.01% of a salt having an anion represented by the following chemical formula 1. Parts by weight to 3 parts by weight,
The polymer component includes a blend of a plurality of polyester-based thermoplastic elastomers, and the blend includes at least a first polyester-based thermoplastic elastomer having a predetermined hardness and a lower hardness than the first polyester-based thermoplastic elastomer. A second polyester-based thermoplastic elastomer,
The content of the second polyester-based thermoplastic elastomer in the entire polymer component is less than that of the first polyester-based thermoplastic elastomer and is 30% by weight or less, and the volume resistivity is 1.0 × 10 ⁶ Ω. Provided is a conductive seamless belt characterized by being cm to 1.0 × 10 ¹⁰ Ω · cm.

（式中、Ｘ_１およびＸ_２は、同じであっても異なってもよく、それぞれが炭素原子、フッ素原子およびスルホニル基（−ＳＯ_２−）を含む炭素数１〜８の官能基である。）

(Wherein, X ₁ and X _2, which may be the same or different, each carbon atom, a fluorine atom and a sulfonyl group (-SO 2 - is a functional group having 1 to 8 carbon atoms _including). )

  The present invention also provides a thermoplastic composition mainly composed of a first polyester thermoplastic elastomer having a predetermined hardness, and a second polyester thermoplastic elastomer having a lower hardness than the first polyester thermoplastic elastomer. A conductive masterbatch containing 1 wt% to 20 wt% of a salt having an anion described in Chemical Formula 1 and a flame retardant are melt-kneaded with an extruder, and the material obtained by the melt-kneading is used. The present invention provides a method for producing a conductive seamless belt, which is extruded from an annular die and formed into a belt shape along a sizing die.

  When performing the method, a flame retardant and a thermoplastic composition mainly composed of a first polyester-based thermoplastic elastomer are kneaded in advance to form a flame retardant master batch, and the flame retardant master batch is charged into the extruder. In addition, a method of extruding the material from the annular die in the vertical direction is particularly effective.

  The present invention further provides an image forming apparatus comprising the conductive seamless belt.

  The D-type hardness of the first polyester-based thermoplastic elastomer measured according to ASTM D2240 is desirably 10 or more higher than the D-type hardness of the second polyester-based thermoplastic elastomer measured in the same manner. Moreover, it is desirable that the D-type hardness of the first polyester-based thermoplastic elastomer measured according to ASTM D2240 is 50 or more.

Anion according to Formula 1, _{X 1} - is _{C n1 H m1 F (2n1-} m1 + 1) -SO 2 - and is, _{X 2} - is _{C n2 H m2 F (2n2-} m2 + 1) -SO 2 - is a An anion is desirable. However, n1 and n2 may be the same or different, and each is an integer of 1 or more. M1 and m2 may be the same or different, and each is an integer of 0 or more.

The cation that forms a salt paired with the anion described in Chemical Formula 1 is preferably any one selected from alkali metals, Group 2A metals, transition metals, and amphoteric metals, and constitutes a cation. More desirably, the metal is lithium.
Examples of the salt having an anion described in Chemical Formula 1 include lithium-bis (trifluoromethanesulfonyl) imide.
The salt having an anion described in Chemical Formula 1 is desirably blended in the thermoplastic composition without using a medium composed of a low molecular weight polyether compound having a molecular weight of 10,000 or less or a low molecular weight polar compound.

The conductive seamless belt of the present invention has a volume resistivity R _LL in a low temperature and low humidity environment (10 ° C., relative humidity 15%) and a volume resistivity R _HH in a high temperature and high humidity environment (32.5 ° C., relative humidity 90%). _but it is desirable that satisfy the relationship of _{log 10 R LL -log 10 R HH} ≦ 2.5.

The conductive seamless belt of the present invention preferably contains melamine cyanurate, which is a flame retardant, in a proportion of 15% by weight to 40% by weight with respect to the total weight of the thermoplastic composition.
At least one coating layer can be provided on the outer peripheral surface side of the conductive seamless belt of the present invention.

  According to the configuration of the present invention, while maintaining the rigidity based on the first polyester-based thermoplastic elastomer having a high hardness as a base, the volume resistivity can be reduced to a level that cannot be achieved with the rigidity. For example, according to the present invention, the volume resistivity can be reduced by an order of magnitude or more than the conventional level.

  In addition, the salt having an anion described in Chemical Formula 1 is less likely to form an agglomerate and less likely to cause embrittlement of the belt. Therefore, variation in the electric resistance value in the belt surface is reduced, and the resistance value depends on the environment. Can also be reduced.

Therefore, according to the present invention, a seamless belt having both sufficient rigidity and conductivity can be obtained, and good durability can be obtained even when continuously used for a long period of time, for example, when it is stretched continuously on a drive shaft. In addition, stable and good image formation can be realized.
For example, when used as an intermediate transfer belt, good transfer performance can be obtained over a long period of time without causing transfer deviation or transfer failure. Further, it can also be used for a conveyor belt, a developing belt, a fixing belt, a belt-type photoreceptor base belt, and the like, and each can provide better performance than conventional ones.

  A conductive seamless belt formed by molding the thermoplastic composition of the present invention includes a polymer component mainly composed of a blend of a plurality of polyester-based thermoplastic elastomers and a salt having an anion represented by the following chemical formula 1. It is out.

（式中、Ｘ_１およびＸ_２は、同じであっても異なってもよく、それぞれが炭素原子、フッ素原子およびスルホニル基（−ＳＯ_２−）を含む炭素数１〜８の官能基である。）

(Wherein, X ₁ and X _2, which may be the same or different, each carbon atom, a fluorine atom and a sulfonyl group (-SO 2 - is a functional group having 1 to 8 carbon atoms _including). )

  The polyester-based thermoplastic elastomer is suitable as a polymer component of a thermoplastic composition for molding a seamless belt because it can achieve both moderate elasticity and flexibility and moderate hardness. Further, a belt mainly composed of a polyester-based thermoplastic elastomer has higher durability than those mainly composed of polyimide, polycarbonate, polyolefin, etc., and is suitable for continuous use and repeated use.

The polyester-based thermoplastic elastomer has good impact resistance, heat resistance and moldability, and the moldability can be further improved by adding a lubricant or the like.
In addition, since the polyester-based thermoplastic elastomer has good oil resistance, the polyester-based thermoplastic elastomer is hardly deteriorated by contact with a toner or the like, and is less likely to contaminate the photoreceptor.
Further, the polyester-based thermoplastic elastomer does not cause problems such as generation of corrosive gas during molding as in the case of using a fluorine-containing polymer.
Since the polyester-based thermoplastic elastomer has good colorability, it is also suitable for obtaining a white belt by blending a flame retardant such as melamine cyanurate or for obtaining a belt colored in another color.

  From the viewpoint of sufficiently obtaining the advantages of the polyester-based thermoplastic elastomer as described above, the polyester-based thermoplastic elastomer is desirably 60% by weight or more, and more desirably 65% by weight or more of the total polymer component.

In the present invention, a blend of a plurality of polyester thermoplastic elastomers having different hardness and content is used. At that time, the first polyester-based thermoplastic elastomer with high hardness is blended more than the second polyester-based thermoplastic elastomer with low hardness. When a blend of a plurality of polyester-based thermoplastic elastomers has the above quantitative relationship, the rigidity based on the first polyester-based thermoplastic elastomer having a high base hardness can be maintained. Further, due to the action of the second polyester-based thermoplastic elastomer having a low hardness, the belt becomes conductive by the conductive salt having an anion described in Formula 1. Therefore, a seamless belt having an optimum volume resistivity within a range of 1.0 × 10 ⁶ Ω · cm to 1.0 × 10 ¹⁰ Ω · cm can be obtained while maintaining an appropriate rigidity.

However, when the blending amount of the second polyester-based thermoplastic elastomer approaches the blending amount of the first polyester-based thermoplastic elastomer, it becomes difficult to maintain the high hardness of the first polyester-based thermoplastic elastomer, and the rigidity of the belt May not be maintained. Therefore, the content of the second polyester-based thermoplastic elastomer in the blend is required to be 30% by weight or less, desirably 5% by weight to 25% by weight.
On the other hand, the content of the first polyester-based thermoplastic elastomer in the blend is desirably 50% by weight or more, and more desirably 60% by weight or more.

  The D type hardness of the first polyester-based thermoplastic elastomer measured according to ASTM D2240 is less stretched and reduces the color misalignment at the time of transfer. From the viewpoint of effectively reducing the electrical resistance, it is desirable that the D-type hardness of the second polyester-based thermoplastic elastomer measured in the same way be 10 or more, and more desirably 20 or more. However, if the hardness difference is too large, the kneadability of the material is deteriorated and the workability to the belt is also deteriorated, so the upper limit of the hardness difference is desirably 50 or less.

  The D-type hardness of the first polyester-based thermoplastic elastomer measured in accordance with ASTM D2240 is preferably 45 or more from the viewpoint of preventing color misregistration of each color toner during primary transfer, and the belt thickness is 200 μm. It is more desirable that it is 48 or more if it is below. However, if the D-type hardness of the first polyester-based thermoplastic elastomer is too high, it is difficult to reduce the volume resistivity. Therefore, the upper limit is desirably set to 85. In addition, the lower limit of the hardness may be 45 or more as long as the thickness of the belt is 200 μm or more and generally there is no problem in driving the belt. If it is less than this, even if the thickness is increased, the rigidity is insufficient in the practical range.

According to the present invention, the D type hardness measured in accordance with ASTM D2240 is 65 or more and the volume resistivity is 1.0 × 10 ⁸ Ω · cm or more and 1.0 × 10 ¹⁰ Ω · cm or less. Thus, it is possible to provide a conductive seamless belt having a thickness of 50 to 200 μm obtained by molding the thermoplastic composition.
As described above, when the hardness is 65 or more, the thickness of the belt is 50 to 200 μm. If the hardness exceeds 200 μm, the rigidity is too high and the drivability is deteriorated. On the other hand, if the belt thickness is as thin as less than 50 μm, the moldability is deteriorated and the belt is easily stretched when driven, and misalignment occurs when the toners of the respective colors are stacked, so that the color image is easily disturbed.

Further, according to the present invention, the D type hardness measured in accordance with ASTM D2240 is 40 or more and less than 65, and the volume resistivity is 1.0 × 10 ⁶ Ω · cm or more and 1.0 × 10 ^8. It becomes possible to provide a conductive seamless belt having a thickness of 200 μm to 500 μm obtained by molding a thermoplastic composition having a resistance of less than Ω · cm.
As described above, when the hardness is 40 or more and less than 65, the hardness is low, and unless the thickness of the belt is 200 μm or more, the color image is liable to be disturbed due to the color misregistration of each color toner due to the elongation of the belt. On the other hand, since the hardness is low, the drivability is good up to a thickness of 500 μm, but when it exceeds 500 μm, the bending rigidity in the vicinity of the drive shaft increases and the drivability deteriorates. Therefore, the thickness of the belt is preferably in the range of 200 to 500 μm.
Further, as the thickness of the belt increases, it is necessary to lower the volume resistivity. When the thickness of the belt increases to about 500 μm and the volume resistivity exceeds 1.0 × 10 ⁸ Ω · cm, a large transfer voltage is required. And the primary transfer rate of the toner is deteriorated. Therefore, as described above, the volume resistivity is set to 1.0 × 10 ⁸ Ω · cm or less.

  Since the melting point of the first polyester-based thermoplastic elastomer is generally related to the amount of the soft segment, the lower one is easier to be conductive and lower in resistance, so that the melting point of the second polyester-based thermoplastic elastomer is higher than the melting point of the second polyester-based thermoplastic elastomer. It is preferably 5 ° C or higher and more preferably 10 ° C or higher. However, if the melting point difference is too large, it is difficult to set the temperature at the time of molding, and the moldability is deteriorated.

  The melting point of the first polyester-based thermoplastic elastomer is desirably 190 ° C. or higher, but if the melting point is too high, it is difficult to reduce the volume resistivity. Therefore, it is desirable that the melting point of the first polyester thermoplastic elastomer is 240 ° C. as the upper limit.

  The melting point of the thermoplastic elastomer can be measured by various thermal analysis methods. For example, according to the DSC (differential scanning calorimetry) method, one or more endothermic peaks of the thermoplastic elastomer are observed. When only one endothermic peak is observed, the endothermic peak temperature becomes the melting point, and when a plurality of endothermic peaks are observed, the higher endothermic peak temperature becomes the melting point.

The blend of a plurality of polyester-based thermoplastic elastomers may be a blend of two-component polyester-based thermoplastic elastomers or may be a blend of three-component or more polyester-based thermoplastic elastomers.
When a blend of three or more polyester thermoplastic elastomers is used, the highest content component is the first polyester thermoplastic elastomer, and the lowest hardness component is the second polyester thermoplastic elastomer. However, the content of the lowest hardness component in the blend is desirably 5% by weight or more.
In addition, you may use the blend of the several component of the same hardness as a 1st polyester-type thermoplastic elastomer. A blend of a plurality of components having the same hardness may be used as the second polyester-based thermoplastic elastomer.

As the first polyester-based thermoplastic elastomer and the second polyester-based thermoplastic elastomer, various ones can be arbitrarily selected as long as their respective hardnesses are different. For example, a polyester polyether type, a polyester polyester type, etc. are mentioned.
The polyester-based thermoplastic elastomer is desirably a copolymer composed of a hard segment made of polyester having an aromatic ring and a low melting point soft segment made of polyether and / or polyester. In particular, in the polyether polyester system, the elastic modulus of the soft segment is stable, and the change in the elastic modulus between the low temperature and low humidity state and the high temperature and high humidity state is small.

  Since the cation of the salt having an anion described in Chemical Formula 1 is captured in the form of being trapped in the vicinity of the ether bond of the polyether or in the vicinity of the ester bond of the polyester, the salt is difficult to ooze out from the system and is good. Can exhibit high conductivity.

  A polyester system comprising a component having a melting point of 150 ° C. or higher when a high polymer is formed with only a high melting point polyester component and having a melting point or softening point of 80 ° C. or less when measured with only a low melting point soft segment component A thermoplastic elastomer is preferred.

  The high melting point polyester segment constituents having the aromatic ring include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, diphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid or esters thereof and glycols having 1 to 25 carbon atoms. And ester-forming derivatives thereof. In addition, it is preferable that terephthalic acid is 70 mol% or more of the total acid component as an acidic component of the high melting point polyester segment constituent component. Examples of the glycol having 1 to 25 carbon atoms include ethylene glycol, 1,4-butanediol, and ester-forming derivatives thereof. Other acid components can also be used as necessary, but these amounts are preferably 30 mol% or less, more preferably 25 mol% or less of the total acid components.

  Examples of the low melting point soft segment made of polyether include polyalkylene ether glycols such as poly (ethylene oxide) glycol and poly (tetramethylene oxide) glycol. Poly (tetramethylene oxide) glycol is preferable from the viewpoint of high melting point and moldability, and a molecular weight of 800 to 1500 is particularly preferable from a low temperature characteristic, and is preferably 15% to 75% of the total weight of the polyester-based thermoplastic elastomer. .

  Lactones are preferably used as the low melting point soft segment made of polyester. As the lactone, caprolactone is most preferable, but enan lactone, caprylolactone, and the like can also be used as other lactones, and two or more of these lactones can be used in combination.

  The copolymerization ratio between the aromatic polyester and the lactone can be selected depending on the application, but the standard ratio is 97 / 3-5 aromatic polyester / lactone by weight ratio. / 95, more generally in the range of 95/5 to 30/70.

  In addition to the polyester-based thermoplastic elastomer, a polymer component such as a known thermoplastic elastomer or thermoplastic resin can be used alone or in combination with the thermoplastic composition as necessary.

  Moreover, in order to improve mechanical strength, you may mix | blend fillers, such as a calcium carbonate, a silica, a clay, a talc, barium sulfate, diatomaceous earth. Furthermore, in the range that does not cause liberation of additives from the belt surface, transfer to contact materials such as bleeding, blooming, and photoreceptor contamination, and in the range that does not adversely affect flame retardancy and conductivity. Acids, fatty acids such as lauric acid, softening agents such as cottonseed oil, tall oil, asphalt substances, and paraffin wax may be blended. As a result, the hardness and flexibility of the belt can be adjusted appropriately. Furthermore, you may mix | blend anti-aging agents, such as imidazoles, amines, and phenols.

  The salt provided with the anion described in Chemical Formula 1 is excellent in the effect of reducing the volume resistivity of the belt by adding a small amount. In addition, this salt is effective in reducing unevenness of the electric resistance in the belt surface because it is unlikely to form agglomerates and hardly cause embrittlement of the belt, like an electronic conductive material such as carbon black.

  The salt with an anion described in Chemical Formula 1 is often white or colorless. Therefore, when imparting conductivity to a seamless belt using this salt as an ion conductive material, it is possible to obtain a white belt, and even when coloring the belt in various colors, the color of the belt is good. is there.

The salt having an anion described in Chemical Formula 1 is stabilized as an anion due to the electron withdrawing property of the fluoro group and the sulfonyl group in the functional groups of X ₁ and X ₂ in Chemical Formula 1, and the ion has a higher dissociation degree. Indicates. Thereby, a very low electric resistance value can be obtained with a small amount of addition. In addition, this salt has high chemical and electrochemical stability with respect to electrodes and the like, and has high safety. In addition, since the usable temperature range is wide, the electrical resistance can be easily adjusted, and there is little variation in the resistance value in the belt surface. It is possible to make the belt less susceptible to contamination. Furthermore, it is easy to obtain at a low price, is a powder at room temperature, is easy to knead, and can smooth the surface skin even if it is extruded. In particular, it is possible to make the extruded skin smooth when extruding a polyether polyester polymer or the like.

X ₁ − in Chemical Formula 1 is preferably C _n1 H _m1 F _{(2n1−m1 + 1)} —SO ₂ —, and X ₂ − is preferably C _n2 H _m2 F _{(2n2−m2 + 1)} —SO ₂ —. In this case, n1 and n2 may be the same or different, and each is an integer of 1 or more. M1 and m2 may be the same or different, and each is an integer of 0 or more.

  The cation that forms a salt with the anion described in Chemical Formula 1 is preferably a cation of an alkali metal, a group 2A metal, a transition metal, or an amphoteric metal. Alkali metals are particularly preferable because they have a low ionization energy and can easily form stable cations. In particular, the metal constituting the cation is preferably lithium having high conductivity.

In addition to the metal cation, a salt having a cation as shown in the following chemical formulas 2 and 3 can also be used.
In the formula, R _{1 to} R ₆ are each an alkyl group having 1 to 20 carbon atoms or a derivative thereof, and R _{1 to} R ₄ , and R ₅ and R ₆ may be the same or different. Among these, a salt composed of a trimethyl-type quaternary ammonium cation, in which three of R _{1 to} R ₄ are methyl groups and the other one is an alkyl group having 7 to 20 carbon atoms or a derivative thereof is an electron. It is particularly preferred because the positive charge on the nitrogen atom can be stabilized by three highly donating methyl groups and the compatibility with the polymer can be improved by other alkyl groups or derivatives thereof.
In addition, in the cation of the formula 2, R ₅ or R ₆ has an electron-donating property, and also stabilizes the positive charge on the nitrogen atom, thereby increasing the stability as a cation. It is possible to obtain a salt having a high degree of dissociation and thus excellent conductivity imparting performance.

Among the salts with anions described in Chemical Formula 1, lithium-bis (trifluoromethanesulfonyl) imide ((CF ₃ SO ₂ ) ₂ NLi) has a melting point of 228 ° C. and kneading and belt processing temperature (200 ° C. ˜240 ° C.) and is particularly preferable because it is more easily incorporated into the polyether segment. _{Others, (C 2 F 5 SO 2} ) 2 NLi, (C 4 F 9 SO 2) (CF 3 SO 2) NLi, (FSO 2 C 6 F 4) (CF 3 SO 2) NLi, (C 8 F 17 SO ₂ ) (CF ₃ SO ₂ ) NLi, (CF ₃ CH ₂ OSO ₂ ) ₂ NLi, (CF ₃ CF ₂ CH ₂ OSO ₂ ) ₂ NLi, (HCF ₂ CF ₂ CH ₂ OSO ₂ ) ₂ NLi, (( CF ₃ ) ₂ CHOSO ₂ ) ₂ NLi or the like can be used, and a plurality of types may be used in combination.

In order to adjust the volume resistivity in the range of 1.0 × 10 ⁶ Ω · cm to 1.0 × 10 ¹⁰ Ω · cm, 100 parts by weight of the total polymer component is added to the salt having the anion described in Chemical Formula 1. 0.01 parts by weight to 3 parts by weight, preferably 0.05 parts by weight to 2.7 parts by weight.
If the amount of the salt having an anion described in Chemical Formula 1 is less than the above range, it is difficult to adjust the resistance value. On the other hand, even if more salt is added than the above range, the effect of reducing the volume resistivity is almost saturated, and it is difficult to further reduce the electrical resistance. If the amount of salt is excessive, the salt may ooze out due to an electric field applied when the belt is used or contact with the photoreceptor (OPC).
It is desirable that the salt having an anion described in Chemical Formula 1 is uniformly dispersed in the thermoplastic composition, that is, in the belt.

In the present invention, the volume resistivity of the conductive seamless belt is set to 1.0 × 10 ⁶ Ω · cm to 1.0 × 10 ¹⁰ Ω · cm, but 1.0 × 10 ⁶ Ω · cm to 1.0 ×. This is particularly effective when realizing a conductive seamless belt having a volume resistivity of 10 ⁸ Ω · cm. The conductive seamless belt having such a volume resistivity is particularly suitable as an intermediate transfer belt, and good transferability can be obtained. However, the seamless belt according to the present invention is naturally effective when used for applications other than the intermediate transfer belt, such as a conveyance belt and a transfer belt.
If the volume resistivity is smaller than the above range, the current tends to flow, so that it may be difficult to hold the charge, and may not function as a member of the image forming apparatus. In order to obtain a volume resistivity sufficient to hold the electrostatic image of the toner, it is necessary to set it to 1.0 × 10 ⁶ Ω · cm or more. On the other hand, if the volume resistivity is larger than the above range, a high voltage may be required for processes such as transfer, charging and toner supply, and transfer efficiency may be lowered.

The salt having an anion described in Chemical Formula 1 is desirably blended without a medium composed of a low molecular weight polyether compound having a molecular weight of 10,000 or less or a low molecular weight polar compound. When such a medium is used, there is a case where the electric resistance value increases greatly when used continuously for a long time, or the medium is precipitated together with ions, and the photosensitive member is likely to be contaminated.
A known method can be used as a method of blending the salt having the anion described in Chemical Formula 1 without using the medium described above. For example, after dry blending the salt with the anion described in Chemical Formula 1 with a polymer component using a Henschel mixer, tumbler, etc., the blend is melted with a single or twin screw extruder, Banbury mixer, kneader, etc. A method such as mixing can be used.
In addition, when a salt containing an anion described in Chemical Formula 1 is blended with a polyester-based thermoplastic elastomer at a high temperature, it is blended under an inert gas atmosphere such as nitrogen as necessary for the purpose of preventing deterioration of the polymer ( Mixing) can also be performed.

The conductive seamless belt of the present invention has a volume resistivity RLL in a low temperature and low humidity environment (10 ° C., relative humidity 15%) and a volume resistivity R _HH in a high temperature and high humidity environment (32.5 ° C., relative humidity 90%). Log ₁₀ R _LL -log ₁₀ R _HH ≦ 2.5 is desirable. Moreover, it is preferable that the difference between the common logarithm value of the maximum value of the volume resistivity in the belt surface and the common logarithm value of the minimum value is 0.5 or less.

From the viewpoint of improving the heat resistance of the conductive seamless belt of the present invention, a flame retardant can be blended in the thermoplastic composition. For example, when melamine cyanurate is contained as a flame retardant in the seamless belt, the volume resistivity of the belt and its environmental dependency are not affected, and the electric resistance of the belt does not change. Therefore, flame retardance can be imparted to the belt while maintaining a predetermined conductivity.
The seamless belt to which flame retardancy is imparted can be used in an image forming apparatus even under high voltage and high temperature conditions without being limited by the state of use, and high image quality can be achieved.

The melamine cyanurate is desirably blended at a ratio of 15% by weight to 40% by weight and more desirably at a ratio of 20% by weight to 35% by weight with respect to the total weight of the thermoplastic composition. If it is less than 15% by weight, it becomes difficult to impart sufficient flame retardancy to the belt, and if it is more than 40% by weight, the molded belt may become brittle.
Since melamine cyanurate has a decomposition temperature of 300 ° C. or higher, it exists in powder form up to this temperature range. For this reason, if the temperature is about the usage environment of the image forming apparatus or the like, bleeding or blooming from the belt surface does not occur, and the photoreceptor is not contaminated. In addition, melamine cyanurate is a nitrogen-based flame retardant, pyrolyzing with combustion heat, replacing oxygen with nitrogen-based gas and preventing combustion, so toxic gases such as toxic gases caused by halogen You can get a good belt for the environment without worrying about the occurrence.
Moreover, since melamine cyanurate is white and acts as an extender pigment, the belt can be easily colored. A white belt can be obtained by containing melamine cyanurate. When a white belt is used, particularly when used as an intermediate transfer belt, toner adhesion can be easily seen, which is preferable for evaluating the cleaning performance.

  At least one coating layer may be formed on the outer peripheral surface side of the conductive seamless belt. For example, when the seamless belt of the present invention is used as an intermediate transfer belt of an image forming apparatus, it is easy to scrape off toner remaining at the time of transfer, to change the detachability of toner, to control surface energy, etc. Depending on the purpose, known methods such as electrostatic coating, spray coating, dipping, brush coating, etc., using known materials such as urethane polymer, acrylic polymer, rubber latex, etc. as the main polymer and dispersed fluorine resin. Can be coated.

  The thickness of the coating layer is preferably 1 μm to 20 μm. Thereby, the further functional enhancement of the belt can be realized. The coating layer such as a coating layer may have a multilayer structure such as two layers or three layers, and can be on the outer peripheral surface side or / and the inner peripheral surface side of the seamless belt, depending on the required performance, The stacking order, stacking thickness, and the like can be set as appropriate.

  When obtaining a thermoplastic composition, the volume resistivity can be effectively lowered by kneading the anion described in Chemical Formula 1 into the second polyester-based thermoplastic elastomer having low hardness. This is because the salt having an anion described in Chemical Formula 1 is easily dispersed in the soft segment of the polyester-based thermoplastic elastomer, and the salt dispersed in the soft segment functions effectively to lower the volume resistance.

  For example, a conductive masterbatch is prepared by blending 1 wt% to 20 wt% of the salt having the anion described in Chemical Formula 1 with the second polyester thermoplastic elastomer having low hardness. The salt having an anion described in Chemical Formula 1 has a conductive masterbatch, so that dispersibility in the composition is increased, and particularly when the amount of the salt is small, the resistance value can be easily adjusted. Become. By kneading and extruding the conductive masterbatch, flame retardant, and thermoplastic composition, the salt is uniformly dispersed, there is little variation in resistance value, and it has moderate elasticity and flame retardancy. A seamless belt can be easily obtained.

  In addition, flame retardants such as melamine cyanurate are pre-kneaded into polymers such as polyester-based thermoplastic elastomers to form a flame retardant masterbatch, which improves the dispersibility of the flame retardant and may occur during belt molding There can be no fouling due to aggregation of flame retardants. Even with a method that does not use a flame-retardant masterbatch, the occurrence of flaws can be prevented by increasing the kneading effect, but the masterbatch method is preferred because it is easier. In the flame retardant masterbatch, the flame retardant is preferably blended in an amount of 30 wt% to 70 wt%, and further 40 wt% to 60 wt%.

  In the conductive master batch, if the amount of the salt having the anion described in Chemical Formula 1 is less than 1% by weight, it is difficult to obtain the effect of making the conductive master batch. On the other hand, if it exceeds 20% by weight, it becomes difficult to knead the salt. The kneading can be performed by a known method such as a Banbury mixer or a kneader, but is preferably performed by drawing a strand with a twin-screw extruder. The kneading temperature of the conductive master batch is preferably 200 ° C. to 250 ° C., and the kneading time is preferably 1 minute to 20 minutes. However, the kneading temperature is preferably 5 ° C. or more higher than the melting point temperature of the second polyester thermoplastic elastomer having low hardness.

  Next, a conductive masterbatch comprising a second polyester-based thermoplastic elastomer and a salt having an anion described in Chemical Formula 1, a first polyester-based thermoplastic elastomer, and, if necessary, other materials such as a flame retardant Is melt-kneaded with an extruder. The melt kneading temperature is preferably 200 ° C. to 250 ° C., and the kneading time is preferably 1 minute to 20 minutes. However, the kneading temperature is preferably 5 ° C. or more higher than the melting point temperature of the polyester thermoplastic elastomer having the highest melting point. Kneading may be performed by a conventional method using a single screw extruder, a twin screw extruder, a closed kneader, an open roll, a kneader, or the like, but a twin screw extruder is preferable because of high kneading efficiency. The material obtained by melt kneading is extruded from an annular die and formed into a belt shape along a sizing die.

  When using a flame retardant, it is desirable that the flame retardant and the polyester-based thermoplastic elastomer are kneaded in advance and put into the extruder as a flame retardant masterbatch. In this case, a conductive masterbatch, a flame retardant masterbatch, and a polyester thermoplastic elastomer are dry blended and kneaded to obtain a belt material. The flame retardant masterbatch preferably has a kneading temperature of 200 ° C. to 250 ° C. and a kneading time of 1 minute to 20 minutes.

  The strand is then drawn and the belt material is pelletized and dried. The pellets are put into a hopper of a single screw extruder and extruded. The wall thickness of the extruded seamless belt is preferably 50 μm to 500 μm. It can be made variable by adjusting the gap of the die lip at the time of extrusion molding and adjusting the discharge amount of the thermoplastic composition and the take-up speed of the belt. The reason for the above range is that when the thickness is less than 50 μm, it becomes difficult to maintain the shape and handling after molding becomes difficult. On the other hand, if it is thicker than 500 μm, the bending rigidity of the belt becomes high and it becomes difficult to suspend the belt on the drive shaft.

  Further, the surface roughness Rz of the outer surface of the seamless belt is preferably 2.0 μm or less, more preferably 1.8 μm or less. As a result, the transfer efficiency, transportability, and toner cleaning properties during image formation can be improved.

  In extrusion molding, the thermoplastic composition melted by the extruder is guided to an annular die, extruded from the die lip, and contact-cooled and cured to a sizing die provided downstream of the die lip to be molded into a belt shape. Can do. The sized continuous cylindrical molded product is further cut by a cutting device provided downstream, and a belt having a predetermined width can be obtained. By forming by extrusion molding in this way, for example, a large-diameter thin belt having a diameter of 168 mm, a thickness of 250 μm, and a width of 400 mm can be easily formed.

The melt coming out of the die lip is not affected by gravity by being pushed out in the vertical direction, the residual strain is reduced, and it is guided to the sizing die while maintaining the cylindrical state, thereby improving the dimensional accuracy. In particular, the direction of extrusion is preferably vertically downward.
The seamless belt of the present invention can be molded by injection molding or the like other than the production method by extrusion molding.

  As described above, the conductive seamless belt of the present invention realizes very small environmental dependence while reducing variations in resistance value. Therefore, the image forming apparatus of the present invention using this, for example, a copying machine, a facsimile, a printer, etc., can obtain a uniform image and has a smaller resistance dependency on the environment. It is not necessary to use a power source, and the power consumption of the entire apparatus can be reduced. Furthermore, the control system can be further simplified, and development time and costs can be reduced by reducing environmental tests during development.

Next, embodiments of the conductive seamless belt of the present invention and an image forming apparatus including the same will be described with reference to the drawings.
FIG. 1 is an example of the main structure of a tandem color printer provided with the conductive seamless belt of the present invention as an intermediate transfer belt 2. The tandem method has independent development units 1a to 1d for each color of BMCY, and can perform printing for four colors almost at the same time. Therefore, the tandem method can print at a higher speed than the four-cycle method.

  The color printer includes primary transfer rolls 3a to 3d, an intermediate transfer belt 2, drive rolls 4a and 4b for driving the intermediate transfer belt, a secondary transfer roll 5 and a fixing unit 7 in addition to the developing units 1a to 1d. ing. Photosensitive bodies 8a to 8d and charging rolls 9a to 9d are incorporated in the developing units 1a to 1d, respectively. The photoconductors 8a to 8d face the primary transfer rolls 3a to 3d, respectively, with the intermediate transfer belt 2 interposed therebetween.

In each developing unit 1, charging, exposure, formation of an electrostatic latent image, and development with toner are performed on the photoconductor 8. The toner image on the photoconductor 8 is copied by the transfer voltage applied to the primary transfer roll 3 on the intermediate transfer belt 2 stretched by the drive shafts 4a and 4b.
The intermediate transfer belt 2 is driven in the direction of the arrow by the drive shafts 4a and 4b, and each color toner is superimposed on a predetermined position to form a color image thereon. The color image formed on the intermediate transfer belt 2 is transferred to a recording medium 6 such as paper by a secondary transfer voltage applied to the secondary transfer roll 5. The toner image on the recording medium 6 is melted and fixed on the recording medium 6 by the fixing unit 7.

FIG. 2 shows an example of a main structure of a one-drum color printer provided with the conductive seamless belt of the present invention as the intermediate transfer belt 33.
In the 1-drum system, a printing unit in which four colors of CMYK are integrated is used, and color printing is performed by rotating the printing unit.

  This color printer includes transfer rollers 30a and 30b, a charging roller 31, a photosensitive member 32, an intermediate transfer belt 33, a fixing roller 34, four color toners 35 (35a, 35b, 35c, and 35d), and a mirror 36.

  When forming an image, first, the photoconductor 32 rotates in the direction of the arrow in the figure, and the photoconductor 32 is charged by the charging roller 31. Thereafter, the laser 37 exposes the non-image portion of the photosensitive member 32 through the mirror 36 to eliminate the charge, and the portion corresponding to the image line portion is charged. Next, the toner 35a is supplied onto the photoconductor 32, and the toner 35a adheres to the charged image line portion to form an image of the first color. This toner image is transferred onto the intermediate transfer belt 33 by applying an electric field to the primary transfer roller 30a.

Similarly, each color image of the toners 35b to 35d formed on the photoconductor 32 is transferred onto the intermediate transfer belt 33, and a full color image composed of four color toners 35 (35a to 35d) is formed on the intermediate transfer belt 33. Is once formed. This full-color image is transferred onto a transfer medium 38 such as paper when an electric field is applied to the secondary transfer roller 30b, and passes through a fixing roller 34 heated to a predetermined temperature. It is fixed on the surface of the body 38.
When performing double-sided printing, the transfer target 38 that has passed through the fixing roller 34 is reversed inside the printer, and the above image forming process is repeated to form an image on the back side again.

  Next, a method for forming a conductive seamless belt of the present invention will be described with reference to the drawings. FIG. 3 shows the belt manufacturing apparatus 10. The belt manufacturing apparatus 10 includes a hopper 11 for charging a material, an extruder 12 for melt-extrusing the charged material, and a crosshead die having an annular die structure in which the central axis of the extruder 12 and the central axis of the die are perpendicular to each other. 13, a gear pump 14 that is disposed between the extruder 12 and the crosshead die 13 and adjusts the amount of extrusion, an inside sizing 15 that is a sizing mold for shaping the extruded annular material B from the inner peripheral surface side, and molding A take-up machine 16 that pulls the annular object B in the vertical direction and an automatic cutting machine 17 that cuts the continuously formed annular object B to a predetermined length are provided. The crosshead die 13 is configured to push the melt vertically downward from the die lip 13a of the annular die.

  The belt molding material is introduced from the hopper 11 of the extruder 12 and melted at 200 ° C. to 250 ° C., and the melt is fed to the crosshead die 13 while adjusting the extrusion amount by the gear pump 14. At this time, the melting temperature is set to a temperature that is 10 ° C. or more higher than the melting point temperature of the polyester thermoplastic elastomer having the highest melting point. The melt is extruded from the die lip 13a of the annular die of the crosshead die 13 in a vertically downward direction at an extrusion speed of 20 to 300 mL / min. The annular material B pushed out from the die lip 13a is cooled along the inside sizing 15 at 70 ° C to 100 ° C, formed into a belt shape, taken down vertically by the take-up machine 16, and taken up by the automatic cutting machine 17 to a predetermined level. Cut to length to become a conductive seamless belt.

Hereinafter, examples and comparative examples of the conductive seamless belt of the present invention will be described in detail.
In the following manner, the materials shown in Table 1 were blended in the proportions shown in Table 1, a thermoplastic composition was prepared, a conductive seamless belt was molded, and the obtained belt was evaluated. The types of materials are shown below. In addition, the unit of the numerical value of Table 1 is a weight part.

<Polyester thermoplastic elastomer>
In the perprene series manufactured by Toyobo Co., Ltd., the following grade names were used. ASTM of each grade polyester-based thermoplastic elastomer
The D type hardness and melting point measured according to D2240 are shown below.
E450BD: D type hardness 78, melting point 222 ° C.
P90BD: D type hardness 57, melting point 203 ° C.
P47D-01K: D type hardness 48, melting point 203 ° C.
P40B: D type hardness 31, melting point 180 ° C.
P30B: D type hardness 29, melting point 160 ° C.

<Conductive salt>
Lithium-bis (trifluoromethanesulfonyl) imide, which is a salt having the anion described in Chemical Formula 1 above, Chemical Formula: (CF ₃ SO ₂ ) ₂ NLi
<Antioxidant>
IRGANOX HP2215 manufactured by Ciba Specialty Chemicals Co., Ltd.
<Flame retardants>
MC640 (melamine cyanurate) manufactured by Nissan Chemical Industries, Ltd.

(Example 1)
(I) Preparation of thermoplastic composition Lithium-bis (trifluoromethanesulfonyl) which is a conductive salt with respect to 20 parts by weight of P47D-01K (D type hardness 48, melting point 203 ° C.) which is a polyester-based thermoplastic elastomer Conductive master is prepared by dry blending imide to 2 parts by weight (that is, a ratio of 10% by weight), charging it into a hopper of a twin screw extruder, and kneading at a temperature of 208 ° C. Got a batch.
The obtained conductive masterbatch, E450BD (D type hardness 78, melting point 222 ° C.) pellets, which is a polyester-based thermoplastic elastomer, and an antioxidant are dry blended so as to have the ratio shown in Table 1. This is put into a hopper of a twin screw extruder, kneaded at a temperature set to 227 ° C., drawn in a molten state, pelletized with water, pelletized with a pelletizer, and dried to form a belt forming material. did.

(Ii) Molding of seamless belt The produced belt forming material is put into the hopper of the extruder of the belt manufacturing apparatus shown in Fig. 3 and melted by operating the extruder. The die temperature is 235 ° C and the inner diameter is 200 mm. The melt was extruded in a vertical direction from an annular die having a gap of 0.5 mm. Then, it is cooled at 80 ° C by following inside sizing with an outer diameter of 188mm, solidified and molded, pulled vertically downward at a take-up speed of 1m / min, and continuously cut by automatic cutting machine to 400mm width. I got a seamless belt.
The inner diameter of the belt was 185 mm, the average thickness was 150 μm, and the belt width was 220 mm.

(Iii) Performance Evaluation The performance of the belt of Example 1 is shown below. Each performance was measured by the method described later.
Volume resistivity: 10 to the 9.5th power (Ω · cm)
In-plane variation: 0.4
Environmental dependency: 1.5
Image out: ○

[Measurement of volume resistivity]
The volume resistivity (Ω · cm) at 30 points in the surface of each belt was measured using a Hiresta UP MCP-HT450 type, URS probe manufactured by Dia Instruments Co., Ltd. under the conditions of a voltage application time of 10 seconds and an applied voltage of 250V. Measured and averaged the measured values of 30 points. The measurement environment was a temperature of 23 ° C. and a relative humidity of 55%.

[In-plane variation]
In the measured values of the volume resistivity at 30 points, the maximum common logarithm value−the minimum common logarithm value was defined as in-plane variation. The value of this in-plane variation is preferably 0.5 or less.

[Environment dependency]
The volume resistivity of each belt was measured in the same manner as described above except that the measurement environment was changed to LL conditions (temperature 10 ° C., relative humidity 15%) and HH conditions (temperature 32.5 ° C., relative humidity 90%). The difference between the common logarithm of the volume resistivity (Ω · cm) under the LL condition and the common logarithm of the volume resistivity (Ω · cm) under the HH condition was defined as environment dependency. The environmental dependency value is preferably 2.5 or less.

[Image output]
Each belt was mounted as an intermediate transfer belt of a color laser printer (WORK KIO-CL500) manufactured by Panasonic Communications Co., Ltd., image formation was performed, and transfer performance was visually evaluated.

[Flame retardance]
Flame retardancy test: VTM2
UL-94: According to the flammability test of plastic materials.
The test was conducted by the method of “thin material vertical combustion test: VTM-0, VTM-1, VTM-2” using the thin film sample as a control. Those that had reached the level of VTM-2 were indicated as “◯”, and those that did not reach the level were indicated as “X”.

(Example 2)
Lithium-bis (trifluoromethanesulfonyl) imide as a conductive salt is dried at a ratio of 2 parts by weight with respect to 10 parts by weight of P30B (D type hardness 29, melting point 160 ° C.) pellets of polyester thermoplastic elastomer P30B. After blending, this was put into a hopper of a twin screw extruder and kneaded at a temperature set at 165 ° C. to obtain a conductive master batch.
Dry blend the obtained conductive masterbatch, P47D-01K (D type hardness 48, melting point 203 ° C.), which is a polyester-based thermoplastic elastomer, and an antioxidant so as to have the ratio shown in Table 1. This is put into a hopper of a twin-screw extruder, kneaded at a temperature of 208 ° C., drawn in a molten state, water cooled, pelletized with a pelletizer, and dried for belt formation. Material was used.

Using the belt-forming material thus obtained, a conductive seamless belt was formed in the same manner as in Example 1 and evaluated in the same manner. Belt dimensions and evaluation results are shown below.
Belt inner diameter = 185 mm, average wall thickness = 250 μm, belt width = 220 mm
Volume resistivity: 10 to the 7.4th power (Ω · cm)
In-plane variation: 0.2
Environmental dependency: 1.1
Image out: ○

(Example 3)
Pellets of polyester-based thermoplastic elastomer P47D-01K (D type hardness 48, melting point 203 ° C.) are dry blended with flame retardant melamine cyanurate at a ratio of 50% by weight, and this is biaxially extruded. The mixture was put into a hopper of the machine and kneaded at a temperature of 227 ° C. to obtain a flame retardant masterbatch.
Moreover, the electroconductive masterbatch was prepared similarly to Example 2.
The obtained flame retardant masterbatch, conductive masterbatch, P47D-01K pellets and antioxidant were dry blended so as to have the ratio shown in Table 1, and this was hopper of a twin screw extruder. The mixture was kneaded with the temperature set at 208 ° C., the strand was drawn in the molten state, the water-cooled one was pelletized with a pelletizer, and the dried one was used as a belt forming material.

Using the belt-forming material thus obtained, a conductive seamless belt was formed in the same manner as in Example 1 and evaluated in the same manner. Belt dimensions and evaluation results are shown below.
Belt inner diameter = 185 mm, average wall thickness = 250 μm, belt width = 220 mm
Volume resistivity: 10 to the 7.4th power (Ω · cm)
In-plane variation: 0.2
Environmental dependency: 1.1
Image out: ○
Flame resistance: ○

(Example 4)
Lithium-bis (trifluoromethanesulfonyl) imide, which is a conductive salt, is dried at a ratio of 2 parts by weight with respect to 20 parts by weight of P40B (D type hardness 31, melting point 180 ° C.), which is a polyester thermoplastic elastomer. After blending, this was put into a hopper of a twin screw extruder and kneaded at a temperature set at 185 ° C. to obtain a conductive master batch.
Dry blend the obtained conductive masterbatch, P47D-01K (D type hardness 48, melting point 203 ° C.), which is a polyester-based thermoplastic elastomer, and an antioxidant so as to have the ratio shown in Table 1. This is put into a hopper of a twin-screw extruder, kneaded at a temperature of 208 ° C., drawn in a molten state, water cooled, pelletized with a pelletizer, and dried for belt formation. Material was used.

Using the belt-forming material thus obtained, a conductive seamless belt was formed in the same manner as in Example 1 and evaluated in the same manner. Belt dimensions and evaluation results are shown below.
Belt inner diameter = 185 mm, average wall thickness = 250 μm, belt width = 220 mm
Volume resistivity: 10 to the power of 7.1 (Ω · cm)
In-plane variation: 0.1
Environmental dependency: 1.2
Image out: ○

(Comparative Example 1)
Lithium-bis (trifluoromethanesulfonyl) imide, which is a conductive salt, is dry blended into pellets of E450BD (D type hardness 78, melting point 222 ° C.), which is a polyester-based thermoplastic elastomer, at a ratio of 5% by weight. Was put into a hopper of a twin screw extruder and kneaded at a temperature set at 227 ° C. to obtain a conductive master batch.
The obtained conductive masterbatch, E450BD pellets and antioxidant were dry blended so as to have the ratio shown in Table 1, and this was put into a hopper of a twin screw extruder, and the temperature was set to 227 ° C. A kneaded, drawn strand in a molten state, water-cooled, pelletized with a pelletizer, and dried to obtain a belt-forming material.

Using the belt-forming material thus obtained, a conductive seamless belt was formed in the same manner as in Example 1 and evaluated in the same manner. Belt dimensions and evaluation results are shown below.
Belt inner diameter = 185 mm, average wall thickness = 150 μm, belt width = 220 mm
Volume resistivity: 10 to the 10.6th power (Ω · cm)
In-plane variation: 0.5
Environmental dependency: 2.1
Image output: × (Transferability was poor)

(Comparative Example 2)
Dry blend of lithium-bis (trifluoromethanesulfonyl) imide, which is a conductive salt, into a pellet of P47D-01K (D type hardness 48, melting point 203 ° C.), which is a polyester-based thermoplastic elastomer, at a ratio of 10% by weight. This was put into a hopper of a twin screw extruder and kneaded at a temperature set to 208 ° C. to obtain a conductive master batch.
The obtained conductive masterbatch, P47D-01K pellets and antioxidant were dry blended so as to have the ratio shown in Table 1, and this was put into a hopper of a twin screw extruder, and the temperature was set to 208. The mixture was kneaded at a temperature of 0 ° C., the strand was drawn in the molten state, the water-cooled one was pelletized with a pelletizer, and the dried one was used as a belt forming material.

Using the belt-forming material thus obtained, a conductive seamless belt was formed in the same manner as in Example 1 and evaluated in the same manner. Belt dimensions and evaluation results are shown below.
Belt inner diameter = 185 mm, average wall thickness = 250 μm, belt width = 220 mm
Volume resistivity: 8.2 to the power of 10 (Ω · cm)
In-plane variation: 0.3
Environmental dependency: 1.2
Image output: △

(Comparative Example 3)
Lithium-bis (trifluoromethanesulfonyl) imide, which is a conductive salt, is dried at a ratio of 10 parts by weight with respect to 100 parts by weight of P40B (D type hardness 31, melting point 180 ° C.) pellets, which is a polyester thermoplastic elastomer. After blending, this was put into a hopper of a twin screw extruder and kneaded at a temperature set at 185 ° C. to obtain a conductive master batch.
The obtained conductive master batch, P40B pellets, P47D-01K (D type hardness 48, melting point 203 ° C.) pellets and antioxidant were dry blended so as to have the ratio shown in Table 1, This is put into a hopper of a twin-screw extruder, kneaded at a temperature of 208 ° C., drawn in a molten state, water-cooled, pelletized with a pelletizer, and dried to form a belt forming material. did.

Using the belt-forming material thus obtained, a conductive seamless belt was formed in the same manner as in Example 1 and evaluated in the same manner. Belt dimensions and evaluation results are shown below.
Belt inner diameter = 185 mm, average wall thickness = 250 μm, belt width = 220 mm
Volume resistivity: 10 to the power of 7.0 (Ω · cm)
In-plane variation: 0.2
Environmental dependency: 1.1
Image output: × (Expansion was seen in the image)
Table 2 summarizes the belt dimensions and performance evaluation results.

  As mentioned above, Examples 1-4 were good also in any evaluation result, and have confirmed that it was an electroconductive seamless belt excellent in practicality. In Example 3, extremely good flame retardancy was achieved.

Example 1 was able to reduce the volume resistivity as compared with Comparative Example 1. In Comparative Example 1, the volume resistivity exceeded 10 ¹⁰ Ω · cm, and the toner could not be sufficiently transferred from the photoreceptor to the belt during the primary transfer. Further, Comparative Example 1 was higher in environmental dependency than Example 1.
Example 2 was also able to reduce the volume resistivity compared to Comparative Example 2.
In both Examples 3 and 4, the volume resistivity could be lowered to 10 ^7.4 and 10 ^7.1 .
On the other hand, since Comparative Example 2 uses P47D-01K having a low hardness of 48 as the composition, the thickness of the belt was relatively increased to 250 μm to suppress color misregistration, but the volume resistivity was 10 ^{8. More than .3} and 10 ^8.0 , a large primary transfer voltage was required, and the toner transfer rate was poor. Therefore, the image output was evaluated as Δ.
The volume resistivity of Comparative Example 3 could be lowered to the same level as in Examples 3 and 4. However, since the rigidity of the belt was inferior to that of Example 4, the image was stretched during the primary transfer.

  In the above-described embodiments, the case where the conductive seamless belt of the present invention is used as an intermediate transfer belt has been described. However, the conductive seamless belt can also be used as a fixing belt, a developing belt, a conveying belt, and the like used in various image forming apparatuses. In particular, when a white belt is used, toner adhesion can be easily visually checked, so that it is suitable for evaluation of cleaning performance and can be suitably used as an intermediate transfer belt.

  In the above-described examples, the single-layer structure seamless belt formed using the thermoplastic composition is described, but a two-layer structure having at least one coating layer or coating layer on the outer peripheral surface side may be used. The coating layer may have a multilayer structure of three or more layers, and may be provided on the outer peripheral surface side and / or the inner peripheral surface side of the seamless belt.

Various polyester polyether-based or polyester-polyester thermoplastic elastomers can be used for the first polyester-based thermoplastic elastomer and the second polyester-based thermoplastic elastomer in addition to those used in the above-described embodiments.
Moreover, various salts can be used for the salt provided with the anion described in Chemical Formula 1 in addition to those used in the above examples. For example, the type of cation may be changed.
Moreover, in the said Example, although the belt was manufactured by extrusion molding, it can also shape | mold by injection molding etc. and can also shape | mold without using a masterbatch.

  As apparent from the above description, according to the present invention, in the seamless belt formed by containing a polyester-based thermoplastic elastomer as a main component and containing a salt having the anion described in Chemical Formula 1 as a conductive agent. While maintaining a certain rigidity, the volume resistivity can be reduced to a level that could not be achieved with the rigidity.

  Therefore, according to the present invention, a conductive seamless belt having suitable physical properties, for example, an intermediate transfer belt, a sheet conveying belt, a developing belt, a fixing belt, a belt-like photoreceptor base belt, and the like are provided according to various requirements. In particular, it is extremely useful in the fields of image forming apparatuses such as copying machines, facsimiles, and printers.

1 is an example of a main structure of a tandem color printer including the conductive seamless belt of the present invention as an intermediate transfer belt. 1 is an example of a main structure of a one-drum type color printer provided with the conductive seamless belt of the present invention as an intermediate transfer belt. It is the schematic of the manufacturing apparatus of an electroconductive seamless belt.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a-1d Developing unit 2 Intermediate transfer belt 3a-3d Primary transfer roll 4a, 4b Drive roll 5 Secondary transfer roll 6 Recording medium 7 Fixing unit 8a-8d Photoconductor 9a-9d Charging roll 10 Belt manufacturing apparatus 11 Hopper 12 Extruder 13 Crosshead die 13a Die lip 14 Gear pump 15 Inside sizing 16 Take-out machine 17 Automatic cutting machine 30a-b Transfer roller 31 Charging roller 32 Photoconductor 33 Intermediate transfer belt 34 Fixing roller 35a-d Toner 36 Mirror 37 Laser 38 Transferred body

Claims (14)

A conductive seamless belt formed by molding a thermoplastic composition,
The thermoplastic composition includes 100 parts by weight of a polymer component and 0.01 to 3 parts by weight of a salt having an anion represented by the following chemical formula 1,
The polymer component includes a blend of a plurality of polyester-based thermoplastic elastomers,
The blend includes at least a first polyester-based thermoplastic elastomer having a predetermined hardness and a second polyester-based thermoplastic elastomer having a lower hardness than the first polyester-based thermoplastic elastomer,
The content of the second polyester-based thermoplastic elastomer in the entire polymer component is less than the first polyester-based thermoplastic elastomer and 30% by weight or less,
A conductive seamless belt having a volume resistivity of 1.0 × 10 ⁶ Ω · cm to 1.0 × 10 ¹⁰ Ω · cm.

(In the formula, X ₁ and X ₂ are each a C 1-8 functional group containing a carbon atom, a fluorine atom, and a sulfonyl group (—SO ₂ —).)   2. The D-type hardness of the first polyester-based thermoplastic elastomer measured according to ASTM D2240 is 10 or more higher than the D-type hardness of the second polyester-based thermoplastic elastomer measured in the same manner. Conductive seamless belt.   The conductive seamless belt according to claim 2, wherein the D-type hardness of the first polyester-based thermoplastic elastomer measured according to ASTM D2240 is 45 or more. In Formula 1, X ₁ − is C _n1 H _m1 F _{(2n1−m1 + 1)} —SO ₂ —, X ₂ − is C _n2 H _m2 F _{(2n2−m2 + 1)} —SO ₂ —, and n1 and n2 The conductive seamless belt according to any one of claims 1 to 3, wherein each is an integer of 1 or more, and m1 and m2 are each an integer of 0 or more.   5. The cation constituting the salt paired with the anion represented by the chemical formula 1 is any one selected from an alkali metal, a group 2A metal, a transition metal, and an amphoteric metal. The conductive seamless belt according to any one of the above.   The conductive seamless belt according to claim 5, wherein the metal constituting the cation is lithium.   The conductive seamless belt according to any one of claims 1 to 6, wherein the salt having an anion represented by Chemical Formula 1 is lithium-bis (trifluoromethanesulfonyl) imide.   The salt having an anion according to Chemical Formula 1 is blended without using a medium composed of a low molecular weight polyether compound having a molecular weight of 10,000 or less or a low molecular weight polar compound. The conductive seamless belt according to item 1. The volume resistivity R _LL in the low temperature and low humidity environment (10 ° C., relative humidity 15%) and the volume resistivity R _HH in the high temperature and high humidity environment (32.5 ° C., relative humidity 90%) are log ₁₀ R _LL -log ₁₀ The conductive seamless belt according to any one of claims 1 to 8, wherein a relationship of R _HH ≦ 2.5 is satisfied.   The melamine cyanurate which is a flame retardant is contained in the ratio of 15 weight%-40 weight% with respect to the total weight of the said thermoplastic composition, The any one of Claims 1 thru | or 9 is included. Conductive seamless belt.   The conductive seamless belt according to any one of claims 1 to 10, further comprising at least one coating layer on an outer peripheral surface side. A thermoplastic composition mainly composed of a first polyester-based thermoplastic elastomer having a predetermined hardness and a second polyester-based thermoplastic elastomer having a lower hardness than the first polyester-based thermoplastic elastomer are represented by the following chemical formula 1. A conductive masterbatch containing 1 to 20% by weight of a salt having an anion and a flame retardant are melt-kneaded with an extruder,
A method for producing a conductive seamless belt, wherein the material obtained by the melt-kneading is extruded from an annular die and formed into a belt shape along a sizing die.

(In the formula, X ₁ and X ₂ are each a C 1-8 functional group containing a carbon atom, a fluorine atom, and a sulfonyl group (—SO ₂ —).)   The flame retardant and the thermoplastic composition mainly composed of the first polyester-based thermoplastic elastomer are pre-kneaded to form a flame retardant master batch, and the flame retardant master batch is charged into the extruder, The manufacturing method of the electroconductive seamless belt of Claim 12 which extrudes material to the orthogonal | vertical direction from the said annular die.   An image forming apparatus comprising the conductive seamless belt according to claim 1.

Images