JPH01262553A - Manufacture of electrophotographic film - Google Patents

Abstract

PURPOSE:To enhance adhesion between a film base and a conductive layer, stability of the film against time lapse, and productivity of the film by ionizing metal particles evaporated in the vacuum evaporation process, accelerating said ions to give high kinetic energy, and allowing them to collide against the film base. CONSTITUTION:One of Pd, Pt, and Ir is sputtered toward the surface of the film base 4 by the vacuum evaporation process, ionized in an atmosphere 10 causing electric discharge, accelerated by an accelerating electrode 11, allowed to collide against the surface of the film base at high speed, and attached to said surface to form the conductive layer, thus permitting the obtained film to be superior in each of the adhesion between the film base and the conductive layer, stability against time lapse, surface conductivity, light transmittance, and productivity by selecting said metal and said processes.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for producing an electrophotographic film having excellent resolution and contrast, which comprises a conductive layer and a photosensitive layer on a film substrate. Specifically, the present invention relates to an improvement in the method for manufacturing the conductive layer of the film.

(Prior Art) In recent years, electrophotographic films have been known which are made of a transparent, electrically insulating thermoplastic polymer film as a substrate, on which a photosensitive layer consisting of a conductive layer and an organic photoconductor is formed. There is.

(Problem to be Solved by the Invention) As a method for forming this transparent conductive layer, a method in which a solution in which a conductive material is dispersed in a film-forming binder is coated on the polymer substrate, or a method in which a metal A method is known in which an undercoat layer made of a swellable electrically insulating polymer material containing a semiconductor compound is formed in advance, and a conductive layer is formed thereon by the above-mentioned conventional method. However, these methods have problems such as insufficient adhesion between the substrate and the conductive layer, poor weather resistance, and poor long-term stability of the film. Other conventional methods include
A method is known in which a conductive layer is formed by depositing metal such as Fe, Cr, Nl, AI, etc. on the substrate by vacuum evaporation. Conductive layers made of these metals do not have good light transmittance due to their characteristics, so in order to obtain the necessary amount of light, it is necessary to
It is necessary to form a thin film layer of about 0 to 80A. However, such a thin metal film has a problem in that if it is left in the atmosphere after being deposited, oxidation progresses on the container, resulting in a change in the electrical resistance value of the conductive layer. In addition, tin oxide, zinc oxide, etc. can be considered as metal oxides that can be used in place of the above metals, but these cases also have the same problems as when the above metals are used. Furthermore, when a vacuum evaporation method is used, there is a problem in that the adhesion between the substrate and the conductive layer thin film becomes low.

Furthermore, there is a conventional method (Japanese Patent Publication No. 52-5814) that uses sputtering to create a thin conductive layer as described above, but since the sputtering method has a slow film formation rate, the production speed is limited by this conventional method. However, there is a problem in that the manufacturing cost is further increased.

The present invention has been made to solve the above problems, and is an electrophotographic film that can improve the adhesion between the film substrate and the conductive layer of the electrophotographic film, the stability of the film over time, and the productivity of the film. The object of the present invention is to provide a method for producing a film.

(Means for Solving the Problems) The method for producing an electrophotographic film of the present invention includes scattering metal particles of one of Pd, PC, and Ir toward the surface of a film substrate using a vapor deposition method, The scattered metal particles are ionized in a discharge atmosphere and accelerated by an accelerating electrode, and the accelerated metal particles are attached to the substrate surface at high speed to form a conductive layer on the substrate. It is something.

The film substrate is made of an insulating material, and is generally made of a polymer film, such as polyester, triacetate, polypropylene, etc.

The discharge atmosphere is formed to ionize the metal particles, and is generally formed by a high-frequency discharge coil to which a high voltage is applied, and this coil is disposed between the evaporation source and the film substrate.

Further, an accelerating electrode for accelerating ionized metal particles is disposed between the discharge coil and the film substrate, preferably close to the film substrate.

Note that, before forming the conductive layer on the surface of the film substrate as described above, it is desirable to clean the surface of the film substrate by exposing the surface of the substrate to a glow discharge atmosphere in advance.

The discharge form for forming a glow discharge atmosphere may be either alternating current glow (including high frequency glow) or direct current glow, and ionization efficiency can also be increased by performing these glow discharges in a magnetic field. It is possible.

Here, an example of an apparatus for carrying out the method of the present invention will be explained using the drawings. A cylindrical rotary support 2 is rotatably arranged inside the vacuum chamber 1, and the thermoplastic polymer substrate 4 sent out from the delivery roll 3 is arranged along the outer periphery of this rotation support 2, and then transferred to a take-up roll. It is wound up by 5. Further, a glow discharge generating mechanism 6 is provided at a portion where the substrate 4 is disposed along the rotary support 2 to expose the surface of the substrate 4 to a glow discharge atmosphere, and
A vapor deposition mechanism 7 for vapor depositing metal onto the substrate 4 is provided at a portion where the substrate 4 is disposed along the rotary support 2 and on the downstream side of the substrate from the position where the glow discharge generating mechanism 6 is disposed. It is arranged. The vapor deposition mechanism 7 includes a crucible 8 as a container for molten metal and means 9 for heating and vaporizing the molten metal in the crucible 8. As this means 9, an electron beam generating means is usually used, but it is also possible to use other resistance heating means or induction heating means. The crucible 8 and the means 9 are arranged at a position where the evaporated metal particles can be efficiently attached to the film substrate. Further, a high-frequency discharge coil 10 for ionizing metal particles evaporated from the crucible 8 is arranged between the crucible 8 and the film substrate 4. For example, this coil 10 has one
A power of approximately IKW is applied at a frequency of 3.56 MHz. Further, an acceleration electrode 11 for accelerating ionized metal particles is provided between the coil lO and the film substrate 4.
are arranged. This electrode 11 has an annular shape,
Ionized vaporized metal particles are allowed to pass through the annulus of this electrode 11. Note that a DC voltage is applied to this electrode 11, and for example -IK is applied to the rotating support 2.
It is set to a value of about V. Although this device is set so that the evaporated metal particles are orthogonally incident on the film substrate 4, it is also possible to set the device so that the evaporated metal particles are obliquely incident.

The glow discharge generating mechanism 6 is arranged at such a position that the glow discharge generated from the mechanism 6 does not interfere with the metal particles generated from the evaporation mechanism 7 in the subsequent process. It is desirable to locate them in close proximity. The rotary support 2 is provided with a cooling vibrator that circulates a coolant around the entire circumference of the inner wall of the side surface, so that the outer wall of the side surface can be maintained at a constant temperature (for example, 60° C.). This makes it possible to cool the substrate 4 that has been heated during vapor deposition or the like.

Furthermore, the inside of this vacuum chamber 1 is configured to be divided into a plurality of rooms as appropriate by shielding plates 12. The reason for dividing the room into a plurality of rooms in this way is mainly to control the attachment location of the vapor flow molecules of the evaporated metal and to maintain the gas concentration in the glow discharge atmosphere at a predetermined value. Further, a gas introduction path 13 for introducing gas for glow discharge is provided. Note that the configuration of the apparatus for carrying out the method of the present invention is not limited to that described above.

Furthermore, regarding the selection of the material for forming the crucible 8, the following experimental results were obtained through experiments conducted by the present researchers. That is, conventionally, a water-cooled copper crucible has been used as a crucible for melting and holding metal, but when a water-cooled copper crucible is used for the high melting point metal, the difference between the temperature of the crucible wall surface and the temperature of the evaporation point of the molten material is Because of the large size, it is difficult to keep the temperature of the entire evaporation source constant, which has the disadvantage that the evaporation rate fluctuates over time, resulting in large film thickness fluctuations. Further, when a carbon crucible is used, a problem arises in that the crucible material and the high melting point metal react to form a compound in the molten material, causing the resistance value of the conductive film to change in the longitudinal direction of the film. However, after repeated experiments using a ceramic crucible for the evaporation material, the variation in the thickness of the conductive film was within the permissible value, and the electrical resistance value in the longitudinal direction of the film was also constant. From these results, it is desirable to use ceramic as the material for the crucible.

Furthermore, the overall transmittance required for an electrophotographic film must be approximately 65 to 75% or more for light with a wavelength of 550 nm, and the thin film constituting the polymer substrate and conductive layer must have a transmittance of 65% to 75% or more for light with a wavelength of 550 nm. A value of about 75 to 90% or more is required for 550 n- light. Furthermore, the surface resistivity of the conductive film must be 108 Ω/C or less, preferably 10 Ω/C or less.
It is 3Ω/cj or less. However, in general, the relationship between the surface resistivity and transmittance of a metal thin film is such that as the transmittance increases, the surface resistivity increases.

When we investigated the surface resistivity and transmittance of the conductive layer of the metal materials, we found that they were platinum group elements and Ag.

The results showed that each metal of Au satisfied the conditions for the electrophotographic film. However, among these metals, Pd, Pt, and Ir exhibited the best characteristics in both surface resistivity and transmittance. Note that after forming a conductive layer on a substrate by the method described above, a photosensitive layer made of a photoconductor material is formed on this conductive layer by a well-known method.

(Function) As shown in the above configuration, in the method of the present invention, when forming a conductive layer, metal particles evaporated by vapor deposition are ionized, accelerated, and transferred to a film substrate in a state with high kinetic energy. A conductive film is formed by colliding with the Therefore, the density between the substrate and the conductive layer can be made as good as when using the sputtering method, and the production speed can be dramatically improved compared to when using the sputtering method, and the manufacturing cost can also be significantly reduced. becomes possible.

In particular, the reduction in adhesion between the substrate and the conductive layer when using the vapor deposition method has been a major problem, but this problem can be solved without using the sputtering method.

Further, in the vapor deposition process, the substrate is heated by radiant heat from the evaporation source and latent heat of the evaporated molecules, and as a result, monomers decomposed from the polymeric material constituting the substrate and other released gases are generated. It is thought that the monomers and decomposed and adsorbed gases exist at the interface between the conductive layer and the polymer substrate formed in this state, which deteriorates the adhesion between the conductive layer and the polymer substrate.
As a result, delamination of the conductive layer occurred. Therefore, before forming a conductive layer by vapor deposition, glow discharge treatment is performed on the surface of the film substrate to clean the substrate surface, and to form irregularities on the surface of the substrate.
It is preferable to increase the adhesion strength of the conductive layer by forming a polar group such as a polar group, and to perform vapor deposition in this state.

Further, depending on the method of the present invention, the metal used for vapor deposition may be P
It is limited to the following metals: d, Pt, and Ir.

This includes metals other than these metals, such as Fe.

This is because the light transmittance of the conductive layer can be significantly improved compared to the case where the conductive layer is formed using a metal such as Cr, Nl, AQ, etc. as a vapor deposition material. If this light transmittance increases, the necessary amount of light can be obtained even if the film thickness is increased.
Oxidation of the conductive layer can be prevented by increasing the film thickness, and as a result, the surface resistivity of the conductive layer can be reduced to a low value. In addition, each of the above-mentioned Pd, Pt, and Ir metals, especially Pd
Because it has excellent acid resistance and few lattice defects, it is ideal as a constituent material for the conductive layer of electrophotographic film.

(Example) A polyester film (thickness 75 μm) was prepared in a vacuum chamber.
(width 300 mm) at a speed of lh/ll1n and guided into a glow processing chamber, Ar gas was introduced into the glow processing chamber to form an Ar gas atmosphere of 1 to 5 mTorr, and a coiled high frequency electrode was heated to 13.58 MI.
Iz high frequency power was applied to perform glow discharge treatment.

The high frequency power was 1-3KW. Thereafter, the film substrate was brought to a film forming quality (2 to 5 X 10' Torr), and Pd, Pt, and Ir were sequentially deposited by electron beam heating to form a conductive layer of 30 to 70 layers. Also,
A high-frequency discharge coil for ionization is placed between the evaporation source and the polymer substrate film, and an accelerating electrode is placed just in front of the polymer substrate. IKWO high-frequency power is applied to the high-frequency discharge coil to generate evaporated metal particles. A DC voltage of -IKv was applied to the accelerating electrode to accelerate the ionized particles and make them adhere to the polymer substrate. The film substrate was then wound up in a winding chamber to form a sample. Example 1 is a sample with a Pd conductive film, Example 2 is a sample with a PT conductive film, and Example 3 is a sample with an Ir conductive film.
And so. In addition, samples in which a Pd conductive film was formed in the same manner as described above without performing the above glow discharge treatment were used in Example 4 (I! thickness 70A) and Example 5 (film thickness BO
A). Furthermore, for comparison with these examples,
Pd is deposited on the film substrate only by vapor deposition without performing the above glow discharge treatment, ionization or acceleration of the evaporated particles.
Samples in which PL and Ir conductive films were formed were each given a comparative Ml of 2.3. Thereafter, the samples of Examples 1 to 5 and Comparative Examples 1 to 3 were evaluated for surface resistance, light transmittance, and adhesion between the film substrate and the conductive layer.

Note that this surface resistance value is expressed in the unit of Ω/C-, and the light transmittance is the total irradiation light m (wavelength 55Qnm) on the film surface.
) is expressed as a percentage. Furthermore, the adhesion was evaluated by attaching a tape to the vapor-deposited layer surface of a 50 m layer x 5 (ha) sample, and calculating the ratio of the area of the conductive layer peeled from the film to the total area by peeling in the 180'' direction. It is expressed as a percentage.The results of these evaluations are shown in Table 1.In addition, in this Table 1, the overall evaluation of each sample is shown. It shows that it has durability and high stability, 0 shows that it can be put to practical use, and x shows that it is not suitable for practical use.

Table 1 As is clear from Table 1 above, the examples have better overall characteristics than the comparative examples.

(Effects of the Invention) As explained above, according to the method for producing an electrophotographic film of the present invention, vapor deposition, ionization treatment of evaporated particles, and acceleration operation are combined, and further, the vapor deposited metal for forming a conductive layer is Pd. , Pt, and Ir, it is excellent in all aspects such as adhesion between the film substrate and the conductive layer, stability of the film over time, surface resistance and light transmittance of the film, and productivity of the film. An electrophotographic film can be produced.

[Brief explanation of the drawing]

The drawing is a schematic diagram showing an example of an apparatus for carrying out the method for producing an electrophotographic film according to the present invention. 1... Vacuum chamber 2... Rotating support body 4.
・・Thermoplastic polymer substrate 6 ・Glow discharge generation mechanism 7 ・Vapor deposition mechanism 8 ・Crucible 1
O... High frequency discharge coil 11... Accelerating electrode

Claims (1)

[Claims] A method for producing an electrophotographic film, which comprises forming a conductive layer made of a metal thin film and a photosensitive layer made of a photoconductor material in this order on an electrically insulating film substrate, comprising: a vapor deposition method; scattering metal particles of one of Pd, Pt, and Ir toward the surface of the substrate of the film, ionizing the scattered metal particles in a discharge atmosphere and accelerating them using an accelerating electrode, A method for producing an electrophotographic film, characterized in that the conductive layer is formed by depositing the accelerated metal particles on the surface of the substrate.