JP2001142315A - Belt for electrophotograph - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a belt for electrophotograph in which crack resistance and anticreep characteristic are compatible. SOLUTION: The belt for electrophotograph consists of at least a polyamide (A), a thermoplastic resin (B) in which tan δ (loss elastic modulus E"/storage elastic modulus E') at 60 deg.C point in dynamic viscoelasticity measurement is <=0.05 and a compatibilizing agent (C). A is contained by 25 to 75 wt.% toward (A+B) standard and B is contained by 75 to 25 wt.% toward (A+B) standard.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic belt used in an image forming apparatus having an electrostatic transfer system such as an LBP (laser beam printer) and a PPC (electrophotographic copying machine).

[0002]

2. Description of the Related Art Conventionally, endless belts are frequently used in electrophotographic copying machines, intermediate transfer devices such as LBPs, developing devices, and photoreceptor devices. For example, when using an endless electrophotographic belt as an intermediate transfer belt,
As shown in the schematic configuration diagram of the image forming apparatus in FIG. 1, the electrophotographic belt has several rollers inserted in a seamless state, and is driven to rotate for a long time while being kept at an appropriate tension via a tension roller.

[0003] An electrophotographic belt supported by a roller while being provided with an appropriate tension as described above must bend when passing through the roller due to long-term use if the belt base material does not have flexibility. Fatigue cracks (hereinafter also referred to as durability cracks) occur at the ends due to stress, which has been a problem.

Further, in an electrophotographic belt (hereinafter, also referred to as an image carrying belt) that carries an image, such as an intermediate transfer belt and a photosensitive belt, the tension of the belt is not increased even when the belt is not used for a long time. Because the roller is held in a hung state, when a certain time has elapsed, the roller shape at that time is retained and remains, which causes a problem that the image appears as streak-like density unevenness with respect to the image. (Deterioration of creep characteristics). If the creep characteristics are poor, special measures such as releasing the tension during storage and transportation of the manufacturer must be taken, which has been a factor in increasing costs.

Therefore, a belt using a fluororesin (ethylene-trifluoroethylene copolymer (ETFE)) has been proposed. However, although it is very resistant to fatigue cracking, it has poor creep properties and has been left for a long period of time. The quality will be reduced.
As a means for preventing fatigue cracking, a belt having a laminated structure based on a rubber-based resin such as an elastomer is known, but this inevitably increases the cost for multilayering. Further, the elastomer has poor dimensional stability, so that an extra control mechanism such as position detection is required, which also increases the cost.

On the other hand, polycarbonate (PC) resin is known as a material having good creep properties, but is not practical because it is very weak against durability cracking. In order to compensate for the drawbacks of PC, PC and polybutylene terephthalate (PBT) or polyethylene terephthalate (PET)
Alloy materials with such resins have been proposed. However, although the durability is improved to some extent, the PBT and PET sides become continuous phases (sea) from the viewpoint of morphology,
Since PC becomes a discontinuous phase (island), the creep characteristic is P
Extremely reduced depending on the characteristics of BT and PET.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide an electrophotographic belt having both good durability cracking characteristics and good creep characteristics.

[0008]

According to the present invention, at least the polyamide (A) has a tan δ (loss modulus E ″ / storage modulus E ′) at 60 ° C. of 0.0 in dynamic viscoelasticity measurement.
5 or less thermoplastic resin (B) and compatibilizer (C)
And an electrophotographic belt comprising 25 to 75% by weight of A based on the (A + B) standard and 75 to 25% by weight of B based on the (A + B) standard.

The electrophotographic belt of the present invention comprises at least
Consists of polyamide (A), thermoplastic resin (B), and compatibilizer (C). That is, the present invention provides an electrophotograph having excellent durability cracking properties and creep properties by alloying a polyamide (A) having excellent durability cracking properties and a thermoplastic resin (B) having excellent creep properties with a compatibilizer (C). It is intended to provide a belt for use. Here, “alloying” means to uniformly mix (blend) two or more kinds of polymers and / or copolymers.

As the polyamide (A) used in the present invention, known polyamides can be used, for example, polyamide 12 (PA12) (12-nylon), polyamide 11 (PA11) (11-nylon), Polyamide 10 (PA10) (10-nylon), Polyamide 9 (PA9) (9-nylon), Polyamide 8 (PA8) (8
Nylon), polyamide 7 (PA7) (7-nylon), polyamide 6 (PA6) (6-nylon), polyamide 6,6 (PA6,6) (6,6-nylon), polyamide 6,10 (PA6, 10) (6,10-nylon) and the like. The polyamide (A) may be used alone or as a mixture of two or more.

Among the above polyamides, it is preferable to use PA12 and PA11 from the viewpoint of low water absorption. Also,
It is more preferable to select PA12 because it has low water absorption and excellent dimensional stability.

The polyamide (A) has a number average molecular weight of 200
It is preferable to be about 00 to 40,000.

[0013] Commercially available polyamide (A) as described above includes, for example, Glylamid L25 (manufactured by EMS) (PA1
2), Rilsan BESN OTL (Toray) (PA11), etc. are available.

The content of the polyamide (A) is from 25 to 75% by weight, preferably from 30 to 70% by weight, more preferably from 4 to 70% by weight based on the total amount (A + B) of A and B described later.
It is 0 to 70% by weight, more preferably 45 to 65% by weight. When the content of the polyamide (A) is too large, streak-like density unevenness occurs on an image due to a decrease in creep characteristics. On the other hand, if the content is too small, cracks will occur at the end of the belt during durability due to a decrease in breaking resistance.

The thermoplastic resin (B) used in the present invention has a tan δ at 60 ° C. in dynamic viscoelasticity measurement.
(Loss elastic modulus E ″ / storage elastic modulus E ′) is 0.05 or less, preferably 0.04 or less, more preferably 0.03 or less.
5 or less. The inventor of the present invention has determined that tan δ (loss elastic modulus E ″ / storage elastic modulus E ′) in dynamic viscoelasticity of resin (B).
Intensive study of the relationship between
It has been found that when nδ is within the above range, good creep properties are maintained. Tanδ at 60 ° C is 0.0
If it exceeds 5, the creep characteristics are rapidly deteriorated, which causes the occurrence of density unevenness.

Tan δ is a value indicating the behavior characteristics of the resin,
That is, the smaller the tan δ, the stronger the resin tends to behave as an elastic component, while the larger the tan δ, the stronger the resin tends to behave as a viscous component.

In this specification, tan δ at 60 ° C. uses a value measured by a dynamic viscoelasticity measuring apparatus (DMS 6100; manufactured by Seiko Instruments Inc.), but it must be measured by the apparatus. However, the measurement may be performed using any device that can be measured according to the same principle as the above device.

The thermoplastic resin (B) is not particularly limited as long as it is a known thermoplastic resin having the above tan δ, but in the present invention, it is preferable to use a thermoplastic resin containing an aromatic compound in the main chain. A thermoplastic resin containing an aromatic ring in the main chain, that is, a thermoplastic resin in which an aromatic ring such as a benzene ring or a naphthalene ring is incorporated in the main chain has high heat resistance and a rigid structure. Therefore, the creep characteristics of the belt are further improved by using a thermoplastic resin containing an aromatic in the main chain and having the above tan δ. The content ratio of the aromatic ring in the main chain is not particularly limited, and is set within a range where the resin can obtain desired heat resistance and rigidity and the belt of the present invention can have excellent creep characteristics.

Examples of such a thermoplastic resin include, for example, high impact polystyrene-modified polyphenylene ether (HIPS-modified PPE (hereinafter sometimes simply referred to as modified PPE)), polyphenylene sulfide (PPS), and non-crystalline polyamide (non-crystalline PA), polyphenylene ether (PPE) and the like. Preferably, modified PPE, PPS, amorphous PA and the like are used. In addition, as the thermoplastic resin (B), as long as they are compatible with each other, two or more kinds of the above-described polymers may be used as a mixture.

The modified PPE is PIPS modified by HIPS.
Specifically, it is an alloy of HIPS and PPE in which HIPS is dispersed in PPE at a molecular level. PS has the best compatibility with PPE, and its blend system has one Tg and forms a molecular dispersion state. This is because the solubility index values of PPE and PS match. HIPS is a known impact-resistant polystyrene, and includes, for example, a styrene-acrylonitrile copolymer, a compatibilized product of polystyrene and a styrene-butadiene copolymer, and the like.

The PPE content in the modified PPE is preferably at least 45% by weight from the viewpoint of heat resistance.

As a commercially available product of such a modified PPE, Iupiace AH60 (tan δ = 0.09 (60 ° C.); manufactured by Mitsubishi Engineering Plastics) is available.

As a commercial product of the above PPS, Torelina B672X01
(Tan δ = 0.034 (60 ° C); manufactured by Toray Industries, Inc.) and the like are available.

The non-crystalline PA is a known non-crystalline polyamide, preferably a polycondensate of a diamine and an aromatic dicarboxylic acid, wherein the diamine has a side chain or the dicarboxylic acid is It is a polycondensate that is an aromatic isoform. Specific examples of such an amorphous PA include, for example, a polycondensate of trimethyl hexamethylenediamine and terephthalic acid, a polycondensate of bis (4-amino-3-methylcyclohexyl) methane and terephthalic acid, or bis ( Aminocyclohexyl) polycondensates of methane and isophthalic acid;

As a commercially available product of such non-crystalline PA, GRILLAMID TR55 (tan δ = 0.028 (60 ° C.); manufactured by EMS)
Etc. are available.

The content of the above-mentioned thermoplastic resin (B) is 75 to 25% by weight, preferably 70 to 30% by weight, more preferably 70 to 30% by weight based on the total amount (A + B) of A and B. Is 60 to 30% by weight, more preferably 55 to
35% by weight.

The compatibilizer (C) used in the present invention
Is not particularly limited as long as alloying of the polyamide (A) and the thermoplastic resin (B) can be achieved by the compatibilizing agent (C). In the present invention, the viewpoint of easy alloying of A and B is considered. It is preferable to use a graft copolymer having a main chain composed of polyolefin and a side chain composed of a vinyl polymer.

In a graft copolymer having a main chain composed of polyolefin and a side chain composed of a vinyl polymer,
Since the polyolefin part as the main chain is compatible with the polyamide (A), while the vinyl-based polymer part as the side chain is compatible with the thermoplastic resin (B), the graft copolymer is It is considered that the compatibility between the polyamide (A) and the thermoplastic resin (B) has been achieved as a whole, and it has become possible to manufacture an electrophotographic belt having both durability cracking and creep characteristics.

The polyolefin constituting the main chain portion of the graft copolymer is a known polyolefin having compatibility with the polyamide (A). For example, one or two or more olefin monomers selected from olefin monomers described below are used. (Co) polymers comprising monomers. In this specification,
“(Co) polymer” means that it may be either a homopolymer or a copolymer.

Examples of the olefinic monomer include unsaturated carboxyl group-containing monomers such as acrylic acid, methacrylic acid, itaconic acid, butenetricarboxylic acid, α-chloroacrylic acid, maleic acid, crotonic acid and fumaric acid. And methyl, ethyl, propyl, butyl, 2-ethylhexyl, cyclohexyl, dodecyl, octadecyl and glycidyl esters of those acids, and maleic anhydride; olefins such as ethylene, propylene, butene- 1, hexene-
1, decene-1, octene-1, styrene and the like; vinyl esters such as vinyl acetate, vinyl propionate,
Vinyl benzoate and the like; vinyl ethers such as vinyl chloride, vinyl methyl ether and vinyl ethyl ether; and acrylamide compounds. Among these, preferred monomers include the above-mentioned unsaturated carboxyl group-containing monomers and olefins, more preferably glycidyl methacrylate, ethylene, styrene, ethyl acrylate, and maleic anhydride.

Specific examples of the polyolefin constituting the main chain of the above graft copolymer include, for example, ethylene-glycidyl methacrylate copolymer, maleic anhydride homopolymer, ethylene-ethyl acrylate-maleic anhydride copolymer, polyethylene , Polypropylene, ethylene-vinyl acetate copolymer and the like. Among them, preferred are polyolefins containing at least one kind of unsaturated carboxyl group-containing monomer, for example, ethylene-glycidyl methacrylate copolymer, maleic anhydride homopolymer, ethylene-ethyl acrylate-maleic anhydride copolymer. It is united. This is because these polymers have higher compatibility with the polyamide (A).

The preferred ethylene-glycidyl methacrylate copolymer for the main chain is 80 to 90% by weight of ethylene.
And glycidyl methacrylate in an amount of 20 to 10% by weight.

The ethylene-ethyl acrylate-maleic anhydride copolymer preferred as the main chain is ethylene 80-
It preferably comprises 90% by weight, 15 to 8% by weight of ethyl acrylate and 5 to 2% by weight of maleic anhydride.

As a method for producing the polyolefin as the main chain portion, a known polymerization method can be used. For example, a high-pressure radical polymerization method can be employed. In the high-pressure radical polymerization method, the above-mentioned predetermined monomers are polymerized at a polymerization pressure of 500 to 400 in the presence of 0.0001 to 1% by weight of a known radical polymerization initiator based on the total weight of all the monomers.
0 kg / cm ^2, preferably 1000~3000kg / cm ^2, the reaction temperature 50 to 400 ° C., preferably under conditions of 100 to 350 ° C., known chain transfer agent, tank type or in the presence of auxiliaries, if desired Contact and polymerization are carried out simultaneously or stepwise in a tubular reactor.

The vinyl polymer constituting the side chain of the graft copolymer used in the present invention is a known vinyl polymer having compatibility with the thermoplastic resin (B). (Co) polymers comprising one or more monomers selected from the group consisting of:

Examples of the above-mentioned vinyl monomers include alkyl methacrylate, alkyl acrylate, styrene, nucleus-substituted styrene such as methyl styrene, dimethyl styrene, ethyl styrene, isopropyl styrene,
Examples thereof include vinyl aromatic monomers such as chlorostyrene and α-substituted styrene such as α-methylstyrene and α-ethylstyrene, acrylonitrile, methacrylonitrile and the like. Preferably, alkyl methacrylate, alkyl acrylate, styrene and acrylonitrile are used.

Specific examples of the vinyl polymer constituting the side chain of the graft copolymer include, for example, polystyrene, acrylonitrile-styrene copolymer, polymethyl methacrylate, polybutyl acrylate, polybutyl methacrylate and the like. Preferred are polystyrene, acrylonitrile-styrene copolymer, and polymethyl methacrylate. The acrylonitrile-styrene copolymer preferably comprises 15 to 35% by weight of acrylonitrile and 85 to 65% by weight of styrene.

The number average degree of polymerization of the vinyl polymer part of the graft copolymer used in the present invention is determined based on the heat resistance of the belt,
From the viewpoint of moldability, 5 to 10,000, preferably 10 to
It is preferably in the range of 5,000.

From the viewpoint of compatibility with the thermoplastic resin (B), when the thermoplastic resin (B) is a modified polyphenylene ether, the vinyl polymer as a side chain of the graft copolymer is polystyrene and / or acrylonitrile-styrene. It is preferably a copolymer, especially HI
From the viewpoint of compatibility with PS, polystyrene is more preferable. At this time, more preferably, the main chain of the graft copolymer is an ethylene-glycidyl methacrylate copolymer.

When the thermoplastic resin (B) is polyphenylene sulfide, the vinyl polymer as a side chain of the graft copolymer is preferably polystyrene, polymethyl methacrylate and / or acrylonitrile-styrene copolymer. At this time, the main chain of the graft copolymer is more preferably a maleic anhydride homopolymer.

When the thermoplastic resin (B) is an amorphous polyamide, the vinyl polymer as a side chain of the graft copolymer is preferably an acrylonitrile-styrene copolymer and / or polystyrene. At this time, more preferably, the main chain of the graft copolymer is a maleic anhydride homopolymer or an ethylene-ethyl acrylate-maleic anhydride copolymer.

The graft copolymer according to the present invention has a polyolefin portion (main chain) from the viewpoint of further improving the durability cracking property and creep property of the obtained belt and improving the surface roughness, heat resistance and dimensional stability of the belt. It is preferable to contain 50 to 80% by weight. Therefore, it contains 50 to 20% by weight of the vinyl polymer portion (side chain).

The grafting method for producing the graft copolymer used in the present invention may be any of the well-known methods such as a chain transfer method and an ionizing radiation irradiation method. This is based on the method shown. The reason for this is that the grafting efficiency is high and secondary aggregation due to heat does not occur, so that the expression of performance is more effective.

That is, 100 parts by weight of the above-mentioned polyolefin as a linear chain is suspended in water, and a known radical (co) polymerization is carried out on 5 to 400 parts by weight of at least one vinyl monomer constituting a side chain. One or two of the volatile organic peroxides
0.1 to 10 parts by weight based on 100 parts by weight of the vinyl monomer and a radical polymerization initiator having a decomposition temperature of 40 to 90 ° C. for obtaining a half life of 10 hours. A solution prepared by dissolving 0.01 to 5 parts by weight based on 100 parts by weight of the total of the system monomer and the radical (co) polymerizable organic peroxide is added, and the radical polymerization initiator is substantially decomposed. The polyolefin is impregnated with a vinyl monomer, a radical (co) polymerizable organic peroxide and a radical polymerization initiator by heating under conditions that do not cause the impregnation.
When the amount reaches 0% by weight or more, the temperature of the aqueous suspension is increased, and a vinyl monomer and a radical (co) polymerizable organic peroxide are copolymerized in a polyolefin to form a graft precursor. Get. This grafting precursor is used for 100 to 30
By kneading at 0 ° C. while melting, the graft copolymer used in the present invention can be obtained.

Therefore, even if the grafting precursor is directly melt-mixed with the polyamide (A) and the thermoplastic resin (B), the grafting precursor becomes a graft copolymer. In addition, a vinyl-based polymer or unreacted polyolefin by-produced during the production of the graft precursor or the graft copolymer may be contained. Further, a mixture of a vinyl precursor or a polyolefin with a grafting precursor or a graft copolymer can also be used. Most preferably, a graft copolymer is used.

In the above production method, when the impregnation ratio is less than 50% by weight, the proportion of the vinyl polymer portion which effectively contributes as a constituent portion of the graft copolymer decreases.
The impregnation rate can be measured by taking out a predetermined amount of polyolefin particles (pellets) from the reaction vessel and measuring the heating residue, whereby the impregnation rate can be determined from the weight difference before and after heating.

Examples of the radical (co) polymerizable organic peroxide include t-butylperoxyacryloyloxyethyl carbonate, t-butylperoxymethacryloyloxyethyl carbonate, t-butylperoxyallyl carbonate, and t-butylperoxymethallyl carbonate. It is preferable to use

Preferred graft copolymers in the present invention, for example, a graft copolymer having a main chain of EGMA (ethylene-glycidyl methacrylate copolymer) and a side chain of AS (acrylonitrile-styrene copolymer) are available under the trade name “MODIPA A4400”. (Nippon Oil & Fats Co., Ltd.). Further, a graft copolymer preferred in the present invention, in which the main chain is composed of EGMA (ethylene-glycidyl methacrylate copolymer) and the side chain is composed of PS (polystyrene), is available, for example, under the trade name "MODIPA A4101" (manufactured by NOF Corporation). It is.

A maleic anhydride homopolymer having a main chain of
A graft copolymer having a side chain of PS (polystyrene), which is preferable in the present invention, is, for example, trade name “MODIPA A810”
0 "(manufactured by NOF CORPORATION). Further, a graft copolymer preferred in the present invention in which the main chain is composed of maleic anhydride homopolymer and the side chain is composed of PMMA (polymethyl methacrylate) is, for example, trade name “MODIPA A8200”.
(Manufactured by NOF CORPORATION). Also, the main chain
A preferred graft copolymer in the present invention comprising E / EA / MAH (ethylene-ethyl acrylate-maleic anhydride copolymer) and AS (acrylonitrile styrene copolymer) in the side chain is, for example, trade name “MODIPA A8400” (Japan (Manufactured by Yushi Co., Ltd.).

The amount of the compatibilizer (C) used is 3 parts per 100 parts by weight of the total amount (A + B) of the polyamide (A) and the thermoplastic resin (B) from the viewpoint of the surface smoothness of the obtained belt. It is desirable that the amount be from 12 to 12 parts by weight, preferably from 5 to 10 parts by weight.

The electrophotographic belt of the present invention preferably contains a known conductive filler for the purpose of imparting conductivity. By imparting conductivity to the electrophotographic belt of the present invention, it can be effectively used as an image carrying belt such as an intermediate transfer belt or a photosensitive belt.

When the belt of the present invention is used as an intermediate transfer belt, if the electric resistance value of the surface of the belt is too high, a predetermined electric field intensity required for toner movement is not generated, and toner transfer is poor, and the density does not reach an appropriate level. . On the other hand, if the resistance is too low, an overcurrent flows, abnormal discharge and the like occur, resulting in a defect such as uneven density. Therefore, when the belt is used as an intermediate transfer belt, the surface electric resistance value is usually 10
It is set in the range of ⁵ to 10 ¹³ Ω / □, preferably 10 ⁷ to 10 ¹⁰ Ω / □. When the belt is used as a photoreceptor belt base material, the surface electric resistance value is usually 0 to
It is set in the range of 10 ⁶ Ω / □, preferably 0 to 10 ³ Ω / □. When the belt is used as a photoreceptor belt, it is necessary to provide an organic photosensitive layer on the surface layer, and this material is used as a base material.

In the case where the belt is used as an intermediate transfer belt, the amount of the conductive filler added is usually polyamide (A) in order to control the surface electric resistance within the above range.
The amount is 3 to 20 parts by weight, preferably 5 to 15 parts by weight, based on 100 parts by weight of the total amount of (A + B) and the thermoplastic resin (B). If the amount is more than 20 parts by weight, the conductivity is too high, the electric resistance value becomes less than 10 ⁵ Ω / □, the mechanical properties are greatly deteriorated, and the product appearance is deteriorated. Also,
If the amount is less than 3 parts by weight, the conductivity is too low, and the electric resistance value exceeds 10 ¹³ Ω / □, and as described above, it does not hold as an electrophotographic belt.

When the belt is used as a photoreceptor belt, in order to control the surface electric resistance within the above range, the amount of the conductive filler added is usually between polyamide (A) and thermoplastic resin (B). 15 to 30 parts by weight, preferably 20 to 25 parts by weight, per 100 parts by weight of the total amount of (A + B)
Parts by weight.

Known conductive fillers can be used, and generally carbon black is used. Among them, acetylene black, furnace black, channel black and the like are preferable, and among these, acetylene black having good dispersibility is particularly preferable.

In this specification, the electric resistance value of the belt surface is JI
S K-6911 means a high resistivity meter (Hiresta I
P; manufactured by Mitsubishi Yuka Co., Ltd.), but it does not have to be measured by the device, and any device can be used as long as it can be measured according to the above JIS standard. May be.

In the present invention, in addition to the above components, additional components can be blended within a range that does not significantly impair the effects of the present invention. Examples include thermoplastic resin components such as polypropylene and polyethylene, and additives such as antioxidants (phenolic and others), stabilizers and lubricants (WAX).

The belt of the present invention may be manufactured by any method as long as the thickness can be controlled within the range described below.
For example, the belt of the present invention can be manufactured using a known molding method after the above-mentioned material is once melted and kneaded by a kneading machine. Known kneaders are used, and examples thereof include a single-screw extruder, a twin-screw extruder, a Banbury mixer, a roll, and a kneader. It is preferable to use a twin-screw extruder in view of the balance between productivity and kneading properties. In addition, as a molding method, a known method is employed, and examples thereof include a continuous melt extrusion molding method, an injection molding method, an inflation molding method, and a blow molding method. From the viewpoint of productivity and dimensional stability, a continuous melt extrusion molding method is preferred.

The thickness of the belt is 50 μm to 1000 μm,
Preferably, it is 100 to 300 μm.

The electrophotographic belt of the present invention as described above is suitable for use as an intermediate transfer belt (intermediate transfer member) or a photosensitive belt.

The case where the conductive belt of the present invention is used as an intermediate transfer belt will be described. FIG. 1 is a schematic partial configuration diagram of an image forming apparatus using the belt of the present invention as an intermediate transfer belt. Reference numeral 1 denotes a photosensitive member, and 4 denotes an intermediate transfer belt. Around the photoreceptor, there is usually a charging device, an exposure optical system for forming an electrostatic latent image on the photoreceptor, a developing device for containing toner, and an intermediate transfer belt for transferring the toner image formed on the photoreceptor surface. An intermediate transfer device for transferring to a recording medium via the printer, a cleaner for removing residual toner, and the like are arranged.
In FIG. 1, for simplicity, a charger 2 for charging a photoreceptor 1, a developing unit 3 for developing an electrostatic latent image formed on the photoreceptor 1 with toner, and a developing unit 3 formed on the photoreceptor 1 Only the intermediate transfer device 10 for transferring the toner image to the recording medium 5 is illustrated.

The intermediate transfer belt 4 has a transfer / transport roller 6
And rotates in the direction of the arrow in synchronization with the photoconductor 1 rotating in the direction of the arrow.

In the image forming apparatus as shown in FIG. 1, first, the surface of the photosensitive member 1 rotating in the direction of the arrow is
And an electrostatic latent image corresponding to the image is formed by an exposure optical system (not shown). The electrostatic latent image is developed into a toner image by the developing device 3.

The developed toner image is transferred to the recording medium 5 by the intermediate transfer device 10. Specifically, a voltage is applied to the intermediate transfer belt by a voltage application device (not shown), and the toner image on the photoconductor 1 is electrostatically transferred to the intermediate transfer belt 4. Then, the toner image formed on the intermediate transfer belt is transferred to the recording paper 5 between the transfer / transfer roller 6 and the pressing roller 7.

In such an image forming apparatus, the intermediate transfer belt 4 is in contact with the photosensitive member 1 via several rollers 6 as shown in FIG. 1 and is stretched by a tension force of 4 to 6 kg. It is in a state of being left. Further, the intermediate transfer belt 4 applies toner from a photoconductor, for example, to Y (yellow), M (magenta), C (cyan), B (black).
Are sequentially rotated at a peripheral speed suitable for the intermediate transfer device, for example, 80 to 160 mm / s. At this time, bending fatigue stress is repeatedly applied depending on the roller diameters of the several rollers 6 and the winding angle of the intermediate transfer belt 4, and the intermediate transfer belt 4 may not reach the set life and may be broken. The belt of the present invention is resistant to such repeated bending fatigue stress. Further, in the above-described image forming apparatus, an intermediate transfer belt is mounted, and a certain time often passes before and after shipment in a state where an external force is applied.
At this time, the shape at the time of application of the external force is maintained, the fold remains, and deformation occurs (deterioration of creep characteristics), which may lead to deterioration of image quality (generation of uneven streaks). The belt of the present invention is hardly deformed even in such a situation.

[0066]

EXAMPLES Materials The following materials were used as the component A. Polyamide (PA) material: Ems PA12 "Grillamide L2
5 "tan δ = 0.105 (60 ° C) (hereinafter simply referred to as" L25 ") The following materials were used as the B component. Modified PPE material: Mitsubishi engineering plastic “Upeiace AH60” tanδ
= 0.009 (60 ° C) (hereinafter simply referred to as “AH60”) PPS material: Toray “Torelina B672X01” tan δ = 0.034 (6
0 ° C) (hereinafter simply referred to as “Torrelina”) Non-crystalline PA material: Emyl's transparent nylon “Grillamide TR”
55 ”tan δ = 0.028 (60 ° C) (hereinafter simply referred to as“ TR55 ”) PBT material:“ Novadur 5010S ”tan δ manufactured by Mitsubishi Engineering Plastics
= 0.057 (60 ° C) (hereinafter simply referred to as “5010S”) The following compatibilizers (all are “MODIPER” manufactured by NOF Corporation) were used as the C component. A4400: graft copolymer whose main chain is EGMA (ethylene-glycidyl methacrylate copolymer) and side chain is AS (acrylonitrile-styrene copolymer) A4101: main chain is EGMA (ethylene-glycidyl methacrylate copolymer), side chain Is a graft copolymer of PS (polystyrene) A8100: Main chain is maleic anhydride homopolymer, side chain is PS
(Polystyrene) graft copolymer A8200: Maleic anhydride homopolymer in main chain, PMMA in side chain
(Polymethyl methacrylate) graft copolymer A8400: graft copolymer whose main chain is E / EA / MAH (ethylene-ethyl acrylate-maleic anhydride copolymer) and whose side chain is AS (acrylonitrile styrene copolymer) Carbon black (acetylene black; manufactured by Denka Corporation) was used as a filler.

EXPERIMENTAL EXAMPLE 1 Examples 1-3 Examples 1 PA12 (L25), modified PPE (AH60) and compatibilizer (A410)
1, A4400) at the ratios shown in Table 1. These materials were kneaded at 60 rpm for 10 minutes using a Labo Plastomill manufactured by Toyo Seiki Co., Ltd.
A 50 μm sheet was produced. Example 2 A sheet having a thickness of 150 μm was produced in the same manner as in Example 1 except that PA12 (L25), PPS (Torelina B672X01) and compatibilizers (A8100, A8200) were used in the proportions shown in Table 1. . Example 3 PA12 (L25), amorphous PA (TR55) and compatibilizer (A810)
0, A8400) was used in the same manner as in Example 1 except that the ratio shown in Table 1 was used to produce a sheet having a thickness of 150 μm.

The obtained sheet was evaluated based on the following. (Folding strength) In accordance with JIS P-8115, the test piece is 15mm wide,
It is cut to a size of 110 mm in length and bent at a bending speed of 175 times / minute and a rotation angle of 9 with an MIT rub resistance tester (manufactured by Toyo Seiki Co., Ltd.).
The number of breaks was measured under the conditions of 0 °, left and right, and a tensile load of 1 kg. From the correlation between the bending strength and the endurance cracking of the actual machine described later (cracking that occurs when the machine is mounted on the actual machine and continuously rotated), no durability cracking occurs when the number of times of destruction is 3000 or more. Cracks tend to occur during durability. In particular, when the number of times of destruction is 1,000 or less, cracking occurs in the early stage of durability. From the above, the number of times of destruction is 1000 times or less.
: 3,000 to 3,000 times, △: 3,000 or more, ◎: 20,000 or more.

(Creep characteristics) width 50 mm, length 130 mm
The evaluation was performed using a test piece cut into a size of. First, as shown in FIG. 2A, the size a of the test piece in the initial state was measured. Next, the test piece was inserted into an aluminum pipe having an inner diameter of φ28 mm, put in a 40 ° C., 95% rh environment for 100 hours, taken out, and left in a 23 ° C., 50% rh environment for 12 hours.
The test piece was extracted from the pipe, and immediately, the dimension b of the test piece was measured as shown in FIG. The creep rate was calculated by the following formula. Creep ratio (%) = (ab) / (a + X) × 100 X indicates the size of the overlapping portion of the test pieces in the pipe as shown in FIG. 2 (C). That is, since a φ28 mm pipe was used in this evaluation, X was 4
2.0 mm (= sheet length 130-28π). When the test piece size b returns to the original length a immediately after being taken out of the pipe, b = a, so the creep rate is represented by zero. On the other hand, when the specimen remains in the pipe immediately after being removed from the pipe, b = −X, and the creep rate is represented by 100. From the correlation between the creep rate and the image density unevenness described later, density unevenness clearly occurs when the creep rate is 80% or more, and density unevenness easily occurs when the creep rate is 75% or more. Therefore, 80% or more is ×, 75% or more and less than 80% is Δ, 40% or more is less than 75%, ○ is 40%
Less than ◎.

(Comprehensive Judgment) Based on the evaluation results of the bending strength and creep characteristics described above, a particularly excellent one was evaluated as ○, a practically acceptable one was evaluated as △, and a practical one was evaluated as ×.

[0071]

[Table 1]

[0072]

[Table 2]

[0073]

[Table 3]

Experimental Example 2 A sheet was produced in the same manner as in Example 1 except that PA12, modified PPE, PPS, amorphous PA, or PBT was used alone. The bending strength and creep characteristics of the obtained sheet were evaluated in the same manner as in Experimental Example 1. The tan δ of each sheet at 60 ° C. was measured as follows. Table 4 shows the results.

(Measurement of tan δ) Using a dynamic viscoelasticity device (manufactured by Seiko Instruments Inc .; Model DMS 6100) in a tensile mode using a sample width of 12 mm × length of 20 mm and thickness of 0.1 to 0.2 mm. Temperature range 30 ° C to 180 ° C
(Temperature rising rate: 2 k / min), measurement frequency: 1 Hz, and read tan δ at 60 ° C.

[0076]

[Table 4]

Example 4 PA12 was used as the A component of the material composition A + B + C.
A sheet was produced in the same manner as in Example 1, except that the materials shown in Table 5 were used as C and C, and that the weight ratio (A: B: C) was 55: 36: 9. The bending strength and creep characteristics of the obtained sheet were evaluated in the same manner as in Experimental Example 1. The evaluation criteria in the comprehensive judgment were the same as in Experimental Example 1.

[0078]

[Table 5]

Experimental Example 3 Examples 5 to 10 and Comparative Examples 1 to 5 Continuous melt extrusion molding was carried out using the pellets obtained by mixing the materials described in Table 6 in the indicated amounts and kneading with a twin-screw kneader. A seamless belt (250 mm width) having an outer diameter of 150 mm and a thickness of 150 μm was manufactured by the method. The obtained belt was evaluated according to the following.

(Surface Roughness and Surface Resistance) The surface roughness and surface resistance of each belt were measured using a surface roughness meter (surfco
m 550; manufactured by Tokyo Seimitsu Co., Ltd.) and a high resistivity meter (Hirester IP; manufactured by Mitsubishi Yuka Co., Ltd.).

(Actual machine endurance cracking) Each seamless belt having a width of 250 mm was mounted on the image forming apparatus having the configuration shown in FIG. 1, and the roll diameter was 28 mm, the rotation speed was 100 mm / sec, the belt tension was 5 kg,
It was rotated 120,000 times at 23 ° C. and 50% rh. Visual observation of belt cracking was performed every 10,000 rotations. At the end of 120,000 rotations, no cracks were generated. At the end of 100,000 rotations, no cracks were generated. At the end of 100,000 rotations, those that had cracked were evaluated as x. did. In the table, the number of rotations when cracks were first confirmed is also shown. Δ and above have no practical problem.

(Image Density Unevenness) Each belt was used as an image forming apparatus having the configuration shown in FIG. 1 (roll diameter φ28 mm, belt tension 5 k
g), and put the device in a 40 ° C, 95% rh environment for 10 minutes.
After leaving it for 0 hours, it was further placed in an environment of 23 ° C and 50% rh for 12 hours.
Left for hours. Thereafter, a magenta halftone image was output immediately, and density unevenness (streaks) due to creep characteristics was evaluated. When it was judged that there was clearly unevenness visually, x was given, when it was not confirmed at all, and Δ when it was slightly confirmed. Δ and above have no practical problem.

(Image Noise) Magenta was carried out in the same manner as in the evaluation method of image density unevenness, except that it was not left in an environment of 40 ° C. and 95% rh and left in an environment of 23 ° C. and 50% rh. A color halftone image was output.
The obtained image was visually observed. × indicates that there was image noise such as density unevenness (vertical streak or nicknamed streak) not caused by creep characteristics and noise due to transfer failure or cleaning failure.
Those that could be confirmed slightly were marked with △. Δ and above have no practical problem. In Example 6, since the amount of the compatibilizer added was too large, the surface smoothness was impaired, and it is considered that the image noise occurred.

[0084]

[Table 6]

[0085]

As described above, according to the present invention, it is possible to obtain a belt with excellent image cracking characteristics and excellent image quality and excellent in creep characteristics.

[Brief description of the drawings]

FIG. 1 is a side view of a main part of an image forming apparatus using a conductive belt of the present invention as an intermediate transfer belt.

FIGS. 2A and 2B are conceptual diagrams for explaining a creep evaluation method, wherein FIG. 2A is a schematic cross-sectional view of a test piece in an initial state, and FIG. 2B is a schematic cross-sectional view of a test piece immediately after being taken out of a pipe. The figure is shown, and (C) shows a schematic sectional view of the test piece in the pipe.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1; Photoreceptor, 2; Charging device, 3; Developing device, 4; Transfer belt, 5; Recording paper, 6; Transfer / conveyance roller, 7;

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masahiko Adachi 2-13-13 Azuchicho, Chuo-ku, Osaka-shi, Osaka F-term in Osaka International Building Minolta Co., Ltd. (reference) 2H032 BA09 BA18 2H035 CA05 CB06 2H068 AA52 AA55 AA58 BB04 BB08 BB10 BB20 BB28 BB35 BB50

Claims (9)

[Claims] 1. At least polyamide (A), a thermoplastic resin (B) having a tan δ (loss modulus E ″ / storage modulus E ′) of not more than 0.05 at 60 ° C. in dynamic viscoelasticity measurement, And a compatibilizer (C), wherein A is (A +
(B) An electrophotographic belt comprising 25 to 75% by weight based on the standard and 75 to 25% by weight of B based on the (A + B) standard. 2. The electrophotographic belt according to claim 1, wherein the compatibilizer (C) is a graft copolymer having a main chain composed of polyolefin and a side chain composed of a vinyl polymer. 3. The composition according to claim 1, wherein the compatibilizer (C) is compounded in an amount of 3 to 12 parts by weight based on 100 parts by weight of the total amount (A + B) of the polyamide (A) and the thermoplastic resin (B). Electrophotographic belt. 4. The electrophotographic belt according to claim 1, wherein the thermoplastic resin (B) contains an aromatic group in the main chain. 5. The electrophotographic belt according to claim 1, wherein the thermoplastic resin (B) is a modified polyphenylene ether, polyphenylene sulfide, or amorphous polyamide. 6. The thermoplastic resin (B) is a modified polyphenylene ether, and the compatibilizer (C) has a main chain of ethylene-glycidyl methacrylate copolymer and a side chain of polystyrene and / or acrylonitrile-styrene. 2. A graft copolymer comprising a polymer.
6. The electrophotographic belt according to any one of items 1 to 5. 7. The thermoplastic resin (B) is a polyphenylene sulfide, and the compatibilizer (C) has a main chain composed of a maleic anhydride homopolymer and a side chain composed of polystyrene, polymethyl methacrylate and / or acrylonitrile. The electrophotographic belt according to any one of claims 1 to 5, which is a graft copolymer comprising a styrene copolymer. 8. The thermoplastic resin (B) is an amorphous polyamide, and the compatibilizer (C) has a main chain of maleic anhydride homopolymer or ethylene-ethyl acrylate-maleic anhydride copolymer, The electrophotographic belt according to any one of claims 1 to 5, wherein the side chain is a graft copolymer composed of an acrylonitrile-styrene copolymer and / or polystyrene. 9. The electric resistance of the surface is 10 ⁵ to 10 ¹³ Ω / □.
The electrophotographic belt according to any one of claims 1 to 8, wherein