JP2001222167A - Sheet for forming internal charge and transfer method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet for forming internal charge capable of forming internal charge advantageous in terms of transferring and holding toner at the time of transfer, and desirably controlling the polarity of the internal charge according to a current direction, and a transfer method in which the sheet is used as an intermediate transfer belt or a transfer carrying belt so as to form the internal charge on the belt and appropriately transfer and hold the toner. SOLUTION: As for this semiconductive sheet for forming the internal charge, the deviation of positive or negative charge density is formed in the vicinity of a center part in the thickness of the sheet in a state where a DC current flows from either surface to the other surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a semiconductive property,
The present invention relates to a sheet for forming an internal charge capable of suitably transferring and holding a toner or the like by forming an internal charge, and a transfer method using the sheet.

[0002]

2. Description of the Related Art In an electrophotographic recording apparatus such as a copying machine, a laser printer, a video printer, a facsimile, and a multifunction machine for forming and recording an image by an electrophotographic method, a photoconductor is used to improve the life of the apparatus. A transfer method that can avoid a method of directly fixing an image formed on an image carrier such as a drum via a recording agent such as a toner onto a recording sheet has been studied. One is a method using an intermediate transfer belt, in which a transfer roller or the like is opposed to an image carrier such as a photoreceptor and a voltage (such as direct current) is applied to transfer the charged toner on the image carrier to the intermediate transfer belt. The toner is temporarily transferred to and held on a belt (primary transfer), and then the charged toner held on the intermediate transfer belt is applied to a recording sheet supplied together with the intermediate transfer belt by using another transfer roll or the like to apply a voltage. Transfer and hold (secondary transfer).

[0003] The other is a system using a transfer / conveying belt, in which a transfer roller or the like is opposed to an image carrier and a voltage (such as direct current) is applied, so that an image is formed on a recording sheet supplied together with the transfer / conveying belt. After the charged toner on the carrier is directly transferred and held (transfer), the recording sheet is conveyed to the fixing device side by the transfer conveyance belt (conveyance).

[0004] As these transfer methods, there are various methods which differ in whether or not the belt is energized, and in the form of charging and discharging of the belt, and the like. A semiconductive belt having an appropriate conductivity has been used in order to properly balance the properties, antistatic properties, and static elimination properties.

As such a semiconductive belt, a semiconductive belt using a film made of polyvinylidene fluoride, an ethylene / tetrafluoroethylene copolymer, polycarbonate or the like (JP-A-5-200904, JP-A-5-200904) -345368, JP Patent Publication) and JP-a-6-95521, that the volume resistivity of the 1 to 10 ¹³ [Omega] cm by blending a conductive filler in a polyimide film (JP-a-5-77252) and the like are known ing. In addition, polyimide-based semiconductive belts lack mechanical properties such as strength and friction resistance and abrasion resistance, causing cracks at belt ends and the like, and deformation due to load during driving, resulting in transfer image deformation. This is an improvement over the problems of conventional resin belts.

[0006]

However, in the above-described transfer method using a semiconductive belt, the mechanism for transferring and holding the charged toner on a semiconductive belt or the like has not been sufficiently elucidated. Only the volume resistivity and surface resistivity of the conductive belt, its uniformity, and the like have been studied as electrical characteristics. In addition to these electrical characteristics, it has been found that the internal charge of the semiconductive belt at the time of transfer greatly affects the transfer and holding performance of the toner.

Accordingly, an object of the present invention is to form an internal charge that is advantageous for transferring and holding the toner during transfer,
Preferably, it is an object of the present invention to provide an internal charge forming sheet capable of controlling the polarity of an internal charge by a current direction. Another object of the present invention is to provide a transfer method in which the internal charge forming sheet is used as an intermediate transfer belt or a transfer / conveying belt so that internal charges are formed on the belt to transfer and hold toner appropriately.

[0008]

Means for Solving the Problems The inventors of the present invention have made intensive studies to achieve the above object, and found that when a direct current is passed through a certain kind of semiconductive sheet, a positive near the center of the sheet thickness is obtained. Or, when a bias of a negative charge density is formed and a DC current is applied in the opposite direction, a phenomenon that a bias of the charge density having a polarity opposite to the bias of the charge density is formed has been found, and further studies have been performed. The invention has been completed.

That is, the sheet for forming an internal charge of the present invention comprises:
It has semi-conductivity, and a bias of positive or negative charge density is formed near the center of the sheet thickness in a state where a direct current is applied from one surface to the other surface.

In the above, it is preferable that when a DC current is applied in a direction opposite to the DC current, a charge density bias having a polarity opposite to the charge density bias is formed.

[0011] It is preferable to use a semiconductive sheet in which carbon particles are dispersed in a polyimide resin.

On the other hand, the transfer method of the present invention uses the internal charge forming sheet described above as an intermediate transfer belt in an electrophotographic recording apparatus, and adjusts the current direction during transfer to the sheet. At the time of primary transfer, a charge density bias of the opposite polarity to the toner charge is formed near the center of the sheet thickness, and at the time of secondary transfer, a charge density bias of the same polarity as the toner charge is formed near the center of the sheet thickness. Things.

According to another transfer method of the present invention, an internal charge forming sheet as described above is used as a transfer / conveying belt in an electrophotographic recording apparatus. To form a charge of
At the time of conveyance after transfer, a charge having a polarity opposite to that of the toner charge is formed inside the internal charge forming sheet.

[Effects] According to the sheet for forming an internal charge of the present invention, as shown in the results of the embodiment, by applying the same direct current as that at the time of transfer, a positive or negative current is applied near the center of the sheet thickness. An uneven charge density can be formed.
For this reason, for example, in the primary transfer in which the charged toner is adsorbed and held, the bias of the charge density having the opposite polarity to that of the charged toner is formed, so that the toner can be attracted by electrostatic force and the transfer and holding of the toner can be performed appropriately. it can.

When a DC current is applied in a direction opposite to the DC current, and a charge density bias having a polarity opposite to that of the charge density is formed, usually, in secondary transfer, a voltage is applied by applying a voltage. Since a direct current in the opposite direction is generated, in the secondary transfer for separating the charged toner, a bias of the charge density having the same polarity as that of the charged toner is formed, so that the transfer of the toner to the recording sheet can be suitably performed by the repulsive force. .

[0016] When a semi-conductive sheet obtained by dispersing carbon particles in the polyimide resin, the reason is not clear, it is easy electrical characteristics as above Symbol (charge distribution characteristics) obtained was found.

On the other hand, according to the transfer method of the present invention, since the sheet for forming an internal charge described above is used as the intermediate transfer belt in the electrophotographic recording apparatus, the charge having the opposite polarity to the toner charge during the primary transfer is used. Density bias,
By forming a bias in the charge density of the same polarity during the secondary transfer, the primary transfer and holding of the toner and the secondary transfer can be suitably performed.

According to another transfer method of the present invention, any one of the above-described sheets for forming an internal charge is used as a transfer / conveying belt in an electrophotographic recording apparatus.
At the time of transfer, a charge having a polarity opposite to the toner charge is formed inside the recording sheet, and at the time of conveyance after the transfer, a charge having a polarity opposite to the toner charge is formed inside the sheet for forming the internal charge, thereby transferring and holding the toner. And transport of the recording sheet can be suitably performed.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in the order of an internal charge forming sheet and a transfer method.

[Internal Charge Forming Sheet] The internal charge forming sheet of the present invention has semiconductivity, and has a DC current flowing from one surface to the other surface. It is sufficient that a bias of positive or negative charge density is formed. For example, as shown in FIGS. The values in the range of 20 C / m ³ are shown. Preferably, when a voltage of 200 V is applied to a sheet having a thickness of about 80 μm, the sheet has a charge density of 0.05 C / m ³ or more, more preferably 0.10 C / m ³ or more.

When a direct current is applied in a direction opposite to that of the direct current, a bias of the charge density having a polarity opposite to the bias of the charge density is preferably formed. Or the relationship between FIG. 4 and FIG. It is not clear why such charge distribution characteristics can be obtained,
The sheet for forming an internal charge has an appropriate semi-conductivity, and the electric resistance has an appropriate anisotropy or non-uniformity in the sheet thickness direction, that is, the dispersed state of the conductive filler is in the sheet thickness direction. It is possible to have appropriate anisotropy and non-uniformity. The semiconductivity at that time is 10 ⁸ to 10 ¹⁶ Ω in volume resistivity.
cm, more preferably ¹⁰ 10 Ωcm to 10 ¹⁴ Ωcm. Here, the volume resistivity is Hiresta IP M
CP-HT260 (produced by Mitsubishi Yuka, probe HR-10
0) at an applied voltage of 500 V, depending on the measurement condition of 1 minute value 2
It is a measured value at 5 ° C. and 60% RH.

The sheet for forming an internal charge having the above-mentioned charge distribution characteristics can be obtained, for example, by dispersing a conductive filler or the like in a resin film.

Examples of the resin to be used include polyimide, polyvinylidene fluoride, ethylene / tetrafluoroethylene copolymer, polycarbonate, etc., as well as polyphenylene sulfide, polyether ether ketone, polyether sulfone, polyether imide, polyamide imide and the like. No. Hereinafter, a preferred example of polyimide will be described in detail.

The polyimide film is formed, for example, by developing a polyamic acid solution obtained by polymerizing tetracarboxylic dianhydride or a derivative thereof and a diamine in a solvent in a solvent, and drying the developed layer to form a film. To form a film, and heat-treat the molded product to convert the polyamic acid to imide.

In the above, any suitable tetracarboxylic dianhydride or the like or diamine which forms the polyamic acid can be used. Incidentally, examples of the tetracarboxylic dianhydride include those represented by the following general formula.

[0026]

Embedded image (However, R is a tetravalent aromatic group, an aliphatic group, a cycloaliphatic group, a complex group thereof, or a group having a substituent.) Specific examples of the above-described tetracarboxylic dianhydride as,
Pyromellitic dianhydride (PMDA), 3,3 ', 4
4'-benzophenonetetracarboxylic dianhydride, 3,
3 ', 4,4'-biphenyltetracarboxylic dianhydride (BPDA), 2,3,3', 4'-biphenyltetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride Examples thereof include anhydrides and 1,2,5,6-naphthalenetetracarboxylic dianhydride.

Further, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,2'-bis (3,4-dicarboxyphenyl) propane dianhydride, bis (3,4-dicarboxyphenyl) ) Sulfone dianhydride and perylene-
3,4,9,10-tetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, ethylenetetracarboxylic dianhydride and the like are also specific examples of the tetracarboxylic dianhydride. can give.

On the other hand, examples of diamines include 4,4'-
Diaminodiphenyl ether (DDE), 3,3′-diaminodiphenyl ether, 4,4′-diaminodiphenylmethane, 3,3′-diaminodiphenylmethane,
3,3′-dichlorobenzidine, 4,4′-aminodiphenyl sulfide, 3,3′-diaminodiphenyl sulfone, 1,5-diaminonaphthalene, m-phenylenediamine and p-phenylenediamine (PDA), 3,3 '
-Dimethyl-4,4'-diaminobiphenyl and benzidine.

Further, 3,3'-dimethylbenzidine, 3,3'-dimethoxybenzidine, 4,4'-diaminophenylsulfone, 4,4'-diaminodiphenylsulfide, 4,4'-diaminodiphenylpropane,
4-bis (β-amino-t-butyl) toluene, bis (p-β-amino-t-butylphenyl) ether and bis (p-β-methyl-δ-aminophenyl) benzene,
Bis-p- (1,1-dimethyl-5-aminopentyl)
Benzene, 1-isopropyl-2,4-m-phenylenediamine, m-xylylenediamine and p-xylylenediamine are also examples of the diamine.

Further, di (p-aminocyclohexyl)
Methane and hexamethylenediamine, heptamethylenediamine and octamethylenediamine, nonamethylenediamine and decamethylenediamine, diaminopropyltetramethylenediamine and 3-methylheptamethylenediamine,
4,4-dimethylheptamethylenediamine, 2,11-
Diaminododecane, 1,2-bis- (3-aminopropoxy) ethane, 2,2-dimethylpropylenediamine, 3-methoxyhexamethylenediamine, 2,5-dimethylhexamethylenediamine and 2,5-dimethylheptamethylenediamine are also included. Examples of the diamine are given.

In addition, 3-methylheptamethylene diamine
And 5-methylnonamethylenediamine, 2,17-dia
Minoeicosadecane or 1,4-diaminocyclohexa
, 1,10-diamino-1,10-dimethyldecane,
1,12-diaminooctadecane, 2,2-bis [4-
(4-Aminophenoxy) phenyl] propane and pipera
Gin, H_Two N (CH_Two )_Three O (CH_Two )_Two O (CH_Two )
NH_Two , H_Two N (CH_Two)_Three S (CH_Two )_Three NH_Two , H_Two
 N (CH_Two )_Three N (CH_Three ) (CH_Two )_Three NH _Two Such
Are also examples of the diamine.

As a solvent for the polymerization reaction of the above-mentioned tetracarboxylic dianhydride and the like with the diamine, an appropriate solvent may be used, but a polar solvent is preferably used from the viewpoint of solubility and the like. Incidentally, examples of the polar solvent include N, N-
N, N-dialkylamides such as dimethylformamide, N, N-dimethylacetamide, N, N-diethylformamide and N, N-diethylacetamide;
N-dimethylmethoxyacetamide, dimethylsulfoxide, hexamethylphosphortriamide, N-methyl-
Examples include 2-pyrrolidone (NMP), pyridine, dimethyl sulfone, tetramethylene sulfone, dimethyltetramethylene sulfone, and the like.

In particular, a polar solvent which can be easily removed from the polyamic acid solution by appropriate measures such as evaporation, substitution, diffusion and the like can be preferably used. In addition, a solvent other than water, such as phenols such as cresol, phenol and xylenol, benzonitrile and dioxane, hexane, benzene and toluene can be used in combination as needed. The use of water is not preferred because the generated polyamic acid is hydrolyzed to lower the molecular weight, which tends to cause a decrease in the strength of the polyimide.

In preparing the polyamic acid, one or more kinds of tetracarboxylic dianhydrides and derivatives thereof, diamines, polar solvents and other solvents may be used. The proportion of the tetracarboxylic dianhydride or the like and the diamine used is generally about equimolar, but is not limited thereto. The monomer concentration at the start of the reaction can be appropriately determined depending on the reaction conditions and the like, but is generally about 5 to 30% by weight, and the reaction temperature is 80 ° C.
Hereinafter, 5 to 50 ° C. is particularly suitable.

As the reaction proceeds, the viscosity of the solution increases. In the present invention, a polyamic acid solution in which the reaction has progressed to a logarithmic viscosity η of 0.5 or more is preferable from the viewpoint of improving the heat resistance of the obtained sheet. The reaction time required to obtain a solution of the polyamic acid in the polymerized state is generally 0.5 to 10 hours based on the above reaction conditions. The above-mentioned logarithmic viscosity η can be calculated by the following equation using the values obtained by measuring the drop time t ₁ of the polyamic acid solution and the drop time t ₀ of the solvent with a capillary viscometer.

Η = In (t ₁ / t ₀ ) / C (where C is the concentration of polyamic acid in the solution (g /
dl). In order to achieve the space charge distribution described above, a polyimide film containing a conductive filler as necessary can be used.

Examples of the conductive filler to be used include carbon black such as Ketjen black and acetylene black; metals such as aluminum and nickel; metal oxide compounds such as tin oxide; and conductive or semiconductive materials such as potassium titanate. One or two or more of powder, a conductive polymer such as polyaniline or polyacetylene, or a solid electrolyte such as a complex of polyethylene oxide and an alkali metal salt or the like can be used, and the type is not particularly limited.

The average particle size of the conductive filler to be used is not particularly limited, and those having a small particle size can be preferably used, for example, in order to suppress variation in electric characteristics due to uneven distribution. From this point, generally, 5 μm based on primary particles is used.
m or less, especially 3 μm or less, particularly 5 nm to 0.02 μm.

The amount of the conductive filler to be used can be appropriately determined in accordance with the type, particle size, dispersibility, etc., from the viewpoint of achieving the above-mentioned electrical characteristics. Generally, 25 parts by weight or less, preferably 1 to 20 parts by weight, particularly 3 to 15 parts by weight, per 100 parts by weight of polyimide (solid content) is used from the viewpoint of preventing a decrease in mechanical properties such as strength of the polyimide film. The amount is preferred.

The use amount of the conductive filler is preferably as small as possible from the viewpoint of maintaining the above-mentioned mechanical properties such as strength in the polyimide film. And the like can be preferably used. In this case, polyimide (solid content) 100
The charge distribution described above can be achieved with less than 5 parts by weight, especially 1-4 parts by weight per part by weight.

For example, when the above-mentioned polyamic acid is prepared, the conductive filler is mixed with the polyimide film by a suitable mixer such as a planetary mixer, a bead mill or a three-roll. Dispersing and blending, and then subjecting it to a polymerization treatment, or a method of mixing and dispersing or dissolving a conductive filler in a previously prepared polyamic acid solution with an appropriate mixer, and then subjecting it to film formation It can be performed by an appropriate method such as.

When a conductive filler is added to the solution for preparing the above-mentioned polyamic acid, an appropriate solvent such as a ball mill or ultrasonic wave is first added to the solvent in order to prevent the dispersion of the electric characteristics due to the uniform dispersion. After dispersing the conductive filler in the above method, a method in which tetracarboxylic dianhydride or a derivative thereof and a diamine are dissolved in the dispersion and subjected to a polymerization treatment can be preferably applied.

As described above, the polyimide film can be obtained by appropriately developing a polyamic acid solution and forming the film. The film thickness can be appropriately determined according to the purpose of use of the semiconductive sheet and the like. Generally, from the viewpoint of mechanical properties such as strength and flexibility, 5 to 50
0 μm, especially 10 to 300 μm, especially 20 to 200 μm
Is preferred.

The sheet for forming an internal charge of the present invention is usually
It can be obtained by molding a polyimide film which is used in a belt shape and shows the above-mentioned charge distribution into a desired belt shape. In that case, a polyimide film composed of two or three or more superimposed layers composed of the same or different layers may be used. When the target belt has a ring shape, it can be formed by an appropriate connection method such as an adhesion method using an adhesive or the like at an end of the film, or can be a seamless ring belt. . The seamless belt has an advantage that an arbitrary portion can be used as a rotation start position without a change in thickness due to superposition, and a control mechanism of the rotation start position can be omitted.

The formation of the above-mentioned seamless belt is as follows.
For example, a method of coating a polyamic acid solution on the inner or outer peripheral surface of a mold by a dipping method, a centrifugal method, a coating method, or the like,
It is developed in a ring shape by an appropriate method such as filling the casting mold, and the developed layer is dried and formed into a belt shape, and the molded product is heat-treated to convert the polyamic acid to imide. It can be carried out by an appropriate method according to the related art, such as a method of recovering from a mold (JP-A-61-95361, JP-A-64-22514, JP-A-3-180).
No. 309). In forming the seamless belt, an appropriate process such as a mold releasing process or a defoaming process can be performed.

[Transfer Method] The transfer method of the present invention uses an internal charge forming sheet as described above as an intermediate transfer belt in an electrophotographic recording apparatus, and adjusts the current direction during transfer to the sheet. At the time of primary transfer, a charge density bias of the opposite polarity to the toner charge is formed near the center of the sheet thickness, and at the time of secondary transfer, a charge density bias of the same polarity as the toner charge is formed near the center of the sheet thickness. Things. In the method using the intermediate transfer belt, a voltage (such as direct current) is applied with a transfer roll or the like facing the image carrier, so that the charged toner on the image carrier is temporarily transferred to the intermediate transfer belt and held ( Primary transfer), and then transfer and hold the charged toner held on the intermediate transfer belt on a recording sheet supplied together with the intermediate transfer belt by applying a voltage using another transfer roll or the like (secondary transfer) (See FIGS. 6 and 7).

In this method, for example, if the toner is negatively charged, primary transfer is performed by applying a voltage using the primary transfer roll or the like as a positive electrode, and the secondary transfer disposed on the side opposite to the primary transfer roll. Since a secondary transfer is performed by applying a voltage using a roll or the like as a positive electrode, the direction of the DC current (or DC component) is reversed in the primary transfer and the secondary transfer. Therefore, by using the sheet for forming an internal charge of the present invention and arranging the front and back sides near the center at the time of primary transfer in such a direction as to form a bias in the charge density having the opposite polarity to the toner charge, the transfer method of the present invention Can be implemented.

At the time of the primary transfer, by forming a charge having a polarity opposite to that of the toner charge not only in the vicinity of the center of the intermediate transfer belt but also on the side surface where the toner is attached, the transfer and holding of the toner is improved. It can be done smoothly. Further, at the time of the secondary transfer, the toner transfer can be performed more smoothly by forming a charge having the same polarity as the toner charge not only near the center of the intermediate transfer belt but also on the side surface where the toner is attached. .

According to another transfer method of the present invention, a charge having a polarity opposite to that of the toner charge is formed inside the recording sheet during transfer by using the above-described sheet for forming an internal charge as a transfer and conveyance belt in an electrophotographic recording apparatus. Then, at the time of conveyance after the transfer, a charge having a polarity opposite to that of the toner charge is formed inside the internal charge forming sheet. In the method using the transfer conveyance belt, a voltage (such as direct current) is applied with a transfer roll or the like facing the image carrier, so that the charged toner on the image carrier is printed on a recording sheet supplied together with the transfer conveyance belt. Is transferred and held (transfer), and then the recording sheet is conveyed (conveyed) by a transfer convey belt (FIG. 3).
reference). In this case, similarly to the above, the transfer method of the present invention can be performed by arranging the front and back sides in any direction using the internal charge forming sheet of the present invention.

The electrophotographic recording apparatus according to the present invention includes an apparatus for forming and recording an image by an electrophotographic method, such as a copying machine, a laser printer, a video printer, a facsimile, and a multifunction peripheral thereof. As the recording sheet, an appropriate printing sheet such as a paper sheet or a plastic sheet can be used, and an appropriate toner capable of performing an adhesion process through static electricity can be used as a toner for forming an image on the recording sheet. Further, the type of DC voltage application (transfer means) and the type of image carrier (drum or belt type, etc.)
Is not particularly limited.

[0051]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments and the like specifically showing the configuration and effects of the present invention will be described below.

Example 1 N-methyl-2-pyrrolidone (NMP) 1674 parts (parts by weight, the same applies hereinafter) dried carbon black (Vulcan XC, manufactured by Cabot Corporation, furnace black)
1 part (corresponding to 4 parts by weight with respect to 100 parts by weight of the polyimide solid content) was mixed in a ball mill at room temperature for 6 hours to obtain a uniform dispersion obtained by mixing 3,3 ′, 4,4′-biphenyltetracarboxylic acid 294.2 parts of anhydride (BPDA) and 108.2 parts of p-phenylenediamine (PDA) were dissolved and stirred in a nitrogen atmosphere at room temperature for 4 hours to carry out a polymerization reaction to obtain a polyamic acid solution.

Next, the above-mentioned polyamic acid solution was added with an inner diameter of 330.
mm, a thickness of 400 μm on the inner peripheral surface of a drum mold having a length of 500 mm via a dispenser, and 1500 rpm
For 10 minutes to form a spread layer having a uniform thickness.
While rotating at rpm, hot air of 60 ° C. is blown from the outside of the drum mold for 30 minutes, then heated at 150 ° C. for 60 minutes, then heated to 300 ° C. at a rate of 2 ° C./min and heated at that temperature for 30 minutes. Then, the solvent was removed, dehydrated ring-closing water was removed, and the imide conversion was performed. The mixture was cooled to room temperature and peeled from the mold to obtain a seamless semiconductive belt having a thickness of 73 to 78 μm.

Example 2 In Example 1, acetylene black (manufactured by Denki Kagaku Kogyo Co., Ltd.) and Ketjen Black (Ketjen Black EC, manufactured by Lion Corporation) were used in place of Vulcan XC, based on 100 parts by weight of polyimide solid content. 3 parts by weight (total 6
Except that an equivalent amount was used, a seamless semiconductive belt having a thickness of 76 to 80 μm was obtained in the same manner as in Example 1.

Test Example The space charge distribution characteristics of the semiconductive belt obtained in the above example were examined using the following apparatus. Five Labs Inc.
Using PEA-101-BM: PEANUTS,
The elastic wave generated by the pulse voltage was converted into an electric signal by a pressure sensor (LiNbO ₃ : 10 μm thick) by the electrostatic stress method, and the movement of the charge inside the polymer film was observed in real time. At that time, a pulse voltage: 50 V (5 ns)
Width), DC applied voltage: 0 to 5 kV, and a 1 mm thick sample of polymethyl methacrylate (PMMA) was used as a reference sample. The results are shown in FIGS.

The semiconductive belt (75) produced in Example 1
1 and 2 show the space charge distribution characteristics of a single layer (thickness: μm). Fig. 1 shows the case where the mold surface during belt production was set to the positive electrode side and DC voltage was applied. Fig. 2 shows that the belt was then inverted and the mold surface was set to the negative electrode side and DC voltage was applied. 3 shows the space charge distribution inside the belt in the case of the above. From these results, it was found that the polarity of the space charge formed inside the belt can be inverted by changing the direction of the current flowing inside the belt. That is, the voltage application direction (current direction) can be determined in consideration of the toner polarity, and the toner transfer and holding can be performed appropriately. FIG. 3 shows the internal space charge distribution when the charged toner (negative polarity) on the photosensitive member as the image carrier is transferred and held on the recording sheet when the recording sheet is supplied together with the transfer conveyance belt. Indicated. As a result, electric charges of opposite polarity are formed inside the recording sheet so that the toner is easily transferred at the time of transfer, and large positive charges are formed inside the transfer conveyance belt after the transfer, which contributes to strong retention of the toner. It is thought that it is.

The semiconductive belt (80) produced in Example 2
4 and 5 show the single space charge distribution characteristics (thickness: μm). Fig. 4 shows the case where the mold surface during belt production was set to the positive electrode side and a DC voltage was applied. Fig. 5 shows that the belt was then turned over and the mold surface was set to the negative electrode side and a DC voltage was applied. 3 shows the space charge distribution inside the belt in the case of the above. From these results, as in the case of FIGS. 1 and 2, the polarity of the space charge formed inside the belt can be inverted by changing the direction of the current flowing inside the belt. In the case of the second embodiment, a slight charge of the opposite polarity is generated on the counter electrode side, but does not significantly affect the transfer and retention of the toner. Rather, the formation of large charges on the mold surface facilitates the transfer (acceptance) of the toner coming to the mold surface and the detachment of the toner leaving the mold surface.

FIG. 6 is a graph inferring the space charge behavior during the primary transfer of the belt obtained in Example 2. Thus, when the toner on the photosensitive member is transferred onto the intermediate transfer belt, the inside of the belt and the mold surface have opposite polarities to the toner, which is advantageous for transfer and holding. FIG. 7 is an estimation of the internal space charge distribution at the time of the secondary transfer in which the toner on the semiconductive belt is transferred to a recording sheet (copy paper). Since the current direction at the time of the secondary transfer is opposite to that at the time of the primary transfer, the charge inside the belt has the same polarity as that of the toner, and is easily separated. At this time, the inside of the recording sheet has a polarity opposite to that of the toner, and it is understood that the toner is easily received.

[Brief description of the drawings]

FIG. 1 is a diagram showing space charge distribution characteristics of a semiconductive belt obtained in Example 1.

FIG. 2 shows a semiconductive belt obtained in Example 1 (reverse arrangement).
Figure showing the space charge distribution characteristics of

FIG. 3 is a diagram showing space charge distribution characteristics when the semiconductive belt obtained in Example 1 is used as a transfer conveyance belt.

FIG. 4 is a diagram showing space charge distribution characteristics of the semiconductive belt obtained in Example 2.

FIG. 5 shows a semiconductive belt obtained in Example 2 (reverse arrangement).
Figure showing the space charge distribution characteristics of

FIG. 6 is a diagram showing space charge distribution characteristics at the time of primary transfer when the semiconductive belt obtained in Example 2 is used as an intermediate transfer belt.

FIG. 7 is a diagram showing space charge distribution characteristics at the time of secondary transfer when the semiconductive belt obtained in Example 2 is used as an intermediate transfer belt.

Claims (5)

[Claims] 1. An internal charge forming member having a semiconductive property and having a positive or negative charge density bias near a center portion of a sheet thickness in a state where a direct current is applied from one surface to the other surface. Sheet. 2. The internal charge forming sheet according to claim 1, wherein when a direct current is applied in a direction opposite to the direct current, a charge density bias having a polarity opposite to that of the charge density is formed. 3. The internal charge forming sheet according to claim 1, comprising a semiconductive sheet in which carbon particles are dispersed in a polyimide resin. 4. The method according to claim 1, wherein the intermediate transfer belt is an intermediate transfer belt in an electrophotographic recording apparatus. A transfer method in which a bias in the charge density having the opposite polarity to the toner charge is formed near the center of the sheet thickness, and a bias in the charge density having the same polarity as the toner charge is formed near the center in the sheet thickness during the secondary transfer. 5. An internal charge forming sheet according to claim 1, wherein a charge having a polarity opposite to that of the toner charge is formed inside the recording sheet at the time of transfer by using the transfer sheet for transfer in an electrophotographic recording apparatus. A transfer method in which a charge having a polarity opposite to that of the toner charge is formed inside the sheet for forming an internal charge during conveyance after transfer.