JP2002192652A - Metallized polyimide film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyimide web-like or endless pipe-like film, with a conductive metallized surface, which is highly adhesive even at high temperature. SOLUTION: A polyimide film (1) has a powder A of a fine fiber-like inorganic compound, with a coefficient of linear expansion equal to or below that of a polyimide resin, which is unevenly distributed and dispersed mostly in the surface part. In addition, the metallized polyimide film is constituted of a conductive thin metal film layer (2B) formed of a conductive metal B by a physical thin film forming means and a conductive thick metal film layer (3) formed by an electroplating process, coherently laminated, in that order, on the surface of the polyimide film. When the film is in the web shape, it can be used, for example, as an FPC substrate and when the film is in the shape of an endless pipe, it can be used, for example, as a heating belt for the electromagnetic induction process of a copying machine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to an improved metallized polyimide film. The film is, for example, F
It is effectively used for PC (flexible print) substrates, copier members and the like.

[0002]

2. Description of the Related Art Polyimides have various excellent properties as compared with other polymers, so that their applications are diversified. Among them, a copper foil and a polyimide film are often bonded and combined to be used as an FPC (flexible print) substrate. Recently, the use as a belt-shaped photosensitive member of a color copying machine employing an intermediate transfer system or as a member of a belt-shaped intermediate transfer member has been studied, and some of them have been put to practical use.

An important factor in an FPC board is how to strongly adhere a thinner copper foil to a polyimide film. Although there is no problem in terms of adhesion, there is a drawback in that the thickness of this copper foil has a production technology upper limit. Therefore, in order to solve this thickness point, for example, copper is vapor-deposited by a vapor deposition method, copper is plated by a plating method (electroless plating-electrolytic plating), or a combination of the two methods is used. And many patent applications have been filed. This means is effective in that it is thinner than a copper foil and that the thickness can be freely controlled, but the problem is the adhesion strength with the film. The means for improving the adhesion are also being studied diligently, and many patent applications have been made and proposed. However, at present, an (ultra-thin copper-clad) FPC board that has sufficient adhesion to be practically used, for example, even for repeated bending and use at high temperatures, has not been obtained. is there.

[0004]

SUMMARY OF THE INVENTION Accordingly, the present inventors have
Conductive metal such as copper is freely adhered to the polyimide film with the desired ultrathin thickness, and even if it is used at high temperatures, it does not peel off even if it is used in a belt shape that performs repeated bending operations. We have been working hard to develop a metallized polyimide film that can be improved to a practical level. As a result, the solution was finally found, and the present invention was reached. The invention thus found is described in the following means.

[0005]

That is, the present invention provides a first aspect of the present invention.
Metallized polyimide film (hereinafter referred to as MPI)
A fine fibrous inorganic compound powder A (hereinafter simply referred to as fine fiber powder A) having a linear expansion coefficient equal to or less than a linear expansion coefficient of a polyimide resin (hereinafter referred to as PI resin). A polyimide film (1) which is unevenly dispersed and dispersed on a surface portion, and the film surface is formed by electroplating with a conductive metal thin film layer (2B) formed by a conductive metal B physical thin film forming means. The conductive metal thick film layer (3) to be formed is successively adhered and laminated.

Further, in connection with the first aspect, the second aspect is provided.
The invention described in claim 10 is also provided.
The invention of claim 7 is directed to an invention for an endless tubular film in which the form of the metallized polyimide film of claim 1 is an endless tubular film. I have. By having such semi-conductivity, semi-conductivity can be imparted to the metallized endless tubular polyimide film according to the first aspect. Having this semi-conductivity also allows, for example, charging from the back surface. For example, it can be used as an intermediate transfer belt member of a color copying machine, and the versatility is further expanded. The present invention is as described above, and will be described in detail in the following embodiments.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION First, the PI resin constituting the base of the M.PI film of the present invention is a generally known thermosetting or thermoplastic aromatic PI resin and aromatic polyamideimide (PAI resin). ), Which are appropriately selected and used. Therefore, aromatic tetracarboxylic dianhydride and aromatic diamine, which are the starting materials for PI resin,
The type of the aromatic tricarboxylic acid monoanhydride and the aromatic diamine in the case of the AI resin, the combination of the respective raw materials, and the number thereof are not particularly limited. Of course, a blend PI resin in which these resins are appropriately blended may be used.

Whether the PI resin is thermosetting or thermoplastic depends on the type of starting material. In other words, if such a raw material in which, for example, two or more —O—, —SO ₂ —, —CO ₂ —, and the like are bonded in the polymer main chain is used, the raw material tends to be thermoplastic, and one or more of these are not used. It becomes thermosetting when the raw materials are combined. On the other hand, the PAI resin is generally thermoplastic because it already has an amide group. In addition, as a special resin, a fluorine-bonded PI resin (for example, a resin having a perfluoroalkyl group substituted with a fluorine atom in a polymer main chain) can be mentioned. This is superior to other resins in terms of mold release properties. The choice of each of the above resins depends on the required characteristics of the application, but a thermosetting PI resin is generally preferred.

The form of the PI resin is (long)
Either a film or an endless (seamless) tubular film provided in claim 5. In any case, in particular, the fine fiber powder A having a low linear expansion coefficient equal to or less than the linear expansion coefficient (thermal expansion coefficient) of the resin is dispersed and contained, and the dispersed and contained state becomes the surface of the film. It is said that many parts are unevenly distributed.

The thickness, width, and (in the case of an endless tubular film) diameter of a PI film (hereinafter, referred to as an A / PI film) in which the fine fiber powder A is unevenly dispersed on the surface have properties of the resin itself. It is appropriate depending on the mechanical properties (strength, flexibility, etc.), usage form, and the like, but is generally 50 to 150 in thickness.
μm, width 1000 mm or less, diameter 600 mm or less. In addition, a long film is generally handled in a web shape.

The above-mentioned A / PI film is particularly specified for the following reasons. First, the reason why the fine fiber powder A is selected will be described. The mechanism of action is unclear, but the conductive metal thin film layer (2
This is due to the fact that the adhesion to B) appears more remarkably than that obtained by other means, and the mixed compatibility with the PI resin is relatively good. However, for these reasons,
It is further limited by the coefficient of linear expansion. This is because the conductive metal thin film layer (2B) and the conductive metal thick film layer (3), which are formed in close contact with the surface of the PI film as a substrate, particularly when used in a high temperature region (for example, 150 to 200 ° C.). This is because the adhesive force between the conductive metal layers to be formed does not decrease and partial peeling does not occur. This effect is considered to be due to the smaller linear expansion of the film. Therefore, even if the powder A corresponds to the fine fiber powder A, the powder A exceeding the linear expansion coefficient of the PI resin to be used is excluded from the present invention because the adhesive force tends to decrease.
Originally, metals and resins are different from each other and have a linear expansion coefficient different from one to two digits. Furthermore, at high temperatures, the difference between the two expansion coefficients becomes larger, and finally appears as an action of lowering the interlayer adhesion. In the present invention, it is considered to be the same as such a general opinion. However, in the present invention, such a phenomenon does not particularly occur only in the fine fiber powder A having a linear expansion coefficient equal to or less than that of the PI resin. It is not clear what mechanism this is.

[0012] Even the fine fiber powder A specified above is further restricted by the dispersion state in the PI film, and it is necessary that the fine fiber powder A is dispersed and distributed unevenly particularly in the surface portion. This means that the dispersion must not be evenly distributed over the entire thickness direction, or conversely, must be distributed and distributed unevenly on the back surface. The reason is as follows. First, by being unevenly distributed on the surface portion, the adhesion of the conductive metal thin film layer (2B) by the physical thin film forming means formed on the film surface becomes stronger. This is because the surface of the film has already been formed with a fine uneven surface (due to the presence of many fine fiber powders A) which effectively acts on the adhesion, and a means for forming a physical thin film of the conductive metal B is further provided there. By doing so, it is supposed that a larger adhesion action acts between the active conductive metal B particles and the fine fiber powder A that fly out at a high speed. In addition, since the fine fiber powder A is present on the surface portion, the flexibility of the PI film itself is not substantially changed, and the smooth rotation required for the belt and the adverse effect on durability can be prevented. Further, since the film is insulated from the front surface to the rear surface, the heating efficiency on the front surface is improved.
Here, the meaning of dispersing and dispersing a lot in the portion to be the surface means that the state of being dispersed in a layer only on the surface is most preferable, but has a large adverse effect on the operation and effect described above. Unless this is the case, some internal dispersion may be present.

The fine fiber powder A is specifically as follows. First, as described above, the powder A needs to have a linear expansion coefficient at least equal to or smaller than the linear expansion coefficient of the PI resin. In terms of numerical values, the coefficient of linear expansion of the PI resin, which is a reference, is generally (depending on the molecular structure) from (1 × 10 ⁻⁵ ) to (9 × 1).
Since it is in the range of 0 ⁻⁵ ) cm / cm / ° C., it is less than this. However, the smaller the difference between the two is, the more the above-mentioned effect is increased. The shape of the powder is, in particular, a fine fibrous shape, provided that it must never be granular. If this is just a particle,
It is in a state where it is easily detached from the surface in a state where it is unevenly distributed on the surface, that fine irregularities appearing on the surface are easily formed irregularly, and that it does not exert a greater effect than the combination effect with the physical thin film forming means by. The reason for this is not clear, but the state of the dispersed arrangement on the surface, PI
It is conceivable that the entanglement with the resin and the form of the powder A itself (especially in the case of a whisker described later) work synergistically.

The meaning of the fibers of the fine fiber powder A is a simple single fiber having a diameter of about several μm and a length of about 1 to 3 mm, which is generally called a chopped fiber, and further called a whisker. A single crystal (whisker crystal) fiber having a diameter of about 3 nm to several μm and a length of about several μm to 500 μm obtained by growing a crystal in a uniaxial direction. The latter whisker-like fibers are more preferred. As a specific compound, for example, the coefficient of linear expansion is 10 ⁻⁶ to 10 ⁻⁷ cm / cm.
Each whisker of chopped glass fiber, potassium titanate, aluminum borate, silicon carbide, silicon nitride, alumina, graphite and the like in the range of the order of / ° C is shown. This is also because the specific gravity is between 2.5 and 4 and it is slightly bulky. This is because the mixing and dispersibility with the molding raw material (described later) is relatively good, and uneven distribution on the surface portion which is developed by molding is more easily performed. Further, whiskers of potassium titanate or aluminum borate are preferred because the effect is further promoted.

The mixing amount of the fine fiber powder A is an amount necessary for preferably exhibiting the above-mentioned effects by being unevenly distributed on the surface of the PI film substrate. If you do, 1 to PI resin
It is 15% by weight, preferably 2 to 10% by weight. When the content is less than 1% by weight, the adhesion effect by the above-mentioned action is not substantially exhibited. On the other hand, if it exceeds 15% by weight, not only the adhesion effect tends to decrease, but also the bending resistance is reduced, and cracks are liable to be formed particularly in the bent use form. The powder A is preferably added in a small amount as much as possible, but in this respect, the whisker-like powder is more effective. This is due to the fact that the surface of the film is likely to be a fine uneven surface which is advantageous for exhibiting a larger adhesive force, and particularly, in the case of an endless tubular film, it is easy to arrange in a circumferential direction in a plane.

The A / PI film is also used in the form of an endless tubular film. In this case, for example, a conductive carbon black powder (hereinafter referred to as CB powder) is further uniformly dispersed throughout the non-surface portion of the film. Can also be provided with semiconductivity (claims 6 and 7). This is because the film is effective when used, for example, as a belt-shaped photoreceptor of a color copying machine or a belt-shaped transfer and heating constant member. In other words, semi-conductivity makes it possible to easily charge with a required amount with a low applied voltage and to easily control the condition of timely charge reduction. Therefore, if the CB powder is dispersed in such a manner that the amount of CB powder is increased on the surface portion, not only this function becomes difficult, but also the adhesion of the conductive metal thin film layer (2B) becomes worse.

The reason why the CB powder is selected is that, if the CB powder is first mixed with the forming material together with the fine fiber powder A and then formed into an endless tubular film by a centrifugal molding method described later, the fine fiber powder is used. This is because the action of dispersing the body A uniformly on the surface portion and dispersing the CB powder evenly works more effectively. This is due to the fact that the bulk density is extremely smaller than other conductive agents. Also, it is easy to mix and disperse with the molding raw material, and a desired electric resistance value can be obtained with a relatively small mixing amount. Here, the desired electric resistance value is 10 ² to 10 ¹² Ω ·
cm, desirably 10 ⁷ to 10 ¹⁰ Ω · cm.

The CB powder has various physical properties (electrical resistance, volatile matter, specific surface area, particle size, pH value, etc.) depending on the production raw materials (natural gas, acetylene gas, coal tar, etc.) and production conditions (combustion conditions). DBP oil absorption etc.). A CB powder which can easily obtain a lower electric resistance value with as small a mixing and dispersion as possible, for example, a CB powder having a structure and a high conductivity index (this is obtained by producing acetylene gas as a raw material) It is preferable to select a CB powder that contains a large amount of volatile components, such as a low pH value, although the conductivity index is not so high. However, CB powder that can provide a lower electric resistance value with a small amount of addition may easily cause variation in the applied electric resistance value. Therefore, it is better to select an appropriate CB powder. If a specific mixing amount is exemplified from this meaning, it is 3 to 20% by weight, preferably 5 to 15% by weight based on the PI resin.

The A / PI film is as described above, but the means for producing the film will now be described.

First, a PI resin solution as a raw material for production (forming material) is prepared. Here, the case where the PI resin is a thermoplastic PI resin, a PAI resin, or a thermosetting PI resin is different.
Generally, the former two have the property of dissolving in an organic solvent even if they are imidized, so at least two components (aromatic tetracarboxylic dianhydride or aromatic tricarboxylic monoanhydride and aromatic diamine) Are polymerized in an organic solvent to proceed to imidization to obtain a thermoplastic PI resin solution or a PAI resin solution at once. However, in the latter case, if the reaction proceeds to imidization, the reaction becomes insoluble in an organic solvent, and thus cannot be obtained as a thermosetting PI resin solution at once. In this case, it is necessary to stop the reaction at the stage of the precursor, that is, polyamic acid (hereinafter referred to as PA acid) to obtain a PA acid solution.

It is necessary to proceed the reaction to a degree of polymerization sufficient to obtain excellent physical properties as a film even with thermoplastic PI resin, PAI resin or PA acid. Concentration) is obtained at a concentration convenient for molding. If the concentration obtained by the reaction is high, it may be adjusted by diluting with the same solvent as the organic solvent used in the reaction. Generally, the solution viscosity is 0.5 to 5
It is better to adjust within the range of Pa · s. The organic solvent is generally known as a solvent for a PI resin, such as N-methylpyrrolidone (hereinafter, NMP), dimethylacetamide,
It is an aprotic organic polar solvent such as dimethyl sulfoxide.

Next, a predetermined amount of the fine fiber powder A or the powder A and the CB powder are added to the obtained PI resin solution (hereinafter referred to as a virgin stock solution) and mixed and dispersed. May be added, for example, a fluorine-based surfactant may be added.
It is better to keep the amount as small as possible, not more than about weight%. The mixing procedure may be as follows. If it is added first, it is mixed well in advance with a mixer equipped with stirring blades. Then, this premixed liquid is transferred to a ball (ceramics) mill stirring mixer, and further mixed and dispersed. The two-stage mixing sufficiently disperses and mixes. When defoaming is required, it is preferred to perform the defoaming quickly while stirring slowly.

The above-prepared stock solution is formed into a long film or an endless tubular film. Here, the main forming conditions are as follows. That is, it is to be uniformly dispersed. For this purpose, the following method can be preferably exemplified.

First, the long film will be described. First, the production stock solution and the virgin stock solution are put into two tanks with stirring blades, and the following can be exemplified as a manufacturing apparatus. Each tank is connected to two slit-shaped nozzles via a flexible tube, and is arranged on a metal belt. The two nozzles are arranged side by side at a predetermined distance from the belt, and the nozzles for the undiluted liquid are arranged rearward in the traveling direction of the belt. The metal belt is provided with a heating means mainly for evaporating the organic solvent, and the heating temperature is controlled so as to gradually increase. The length of the metal belt is appropriately determined mainly depending on the relationship with the molding speed. In particular, it is preferable that stirring is always performed particularly in the production stock solution tank. This is because the fine fiber powder A is always kept in a uniformly dispersed state.

On the surface of the metal belt rotating at a constant speed, the undiluted production liquid is discharged from the slit nozzle at a predetermined discharge amount to form a coating film. In this case, the liquid may be discharged, but may be sprayed. The latter is better for controlling a smaller thickness. Next, a virgin stock solution is discharged from the virgin stock solution nozzle at a predetermined discharge rate and laminated on the coating film surface. The timing of the latter ejection is shifted, but the shifting time is preferably a time during which the surface of the coated undiluted solution is in a slightly dry state. Here, the discharge amount of the undiluted production liquid is set to be smaller than that of the undiluted virgin liquid, for example, so as to be within 15% of the total thickness of the finally obtained A / PI film. This is because it is unevenly distributed on the above-mentioned surface portion. The coating film on the laminated belt is gradually heated to a high temperature, and the contained organic solvent is gradually evaporated and gradually removed. The removal amount is about 70 to 90%, and 10 to 30% is reduced. It is better to leave it.
This is because it is not preferable to remove all of the solvent on the belt at once, since this may lead to roughening of the film surface. Therefore, the temperature here is preferably changed stepwise within a range of about 100 to 200 ° C. In the case of using a PA acid, it is necessary to carry out imidation in addition to evaporation and removal of the solvent.
(0 ° C.), it is preferable not to carry out on the belt but to carry out through a separate tunnel-shaped hot-air drying oven.

The self-supporting film on the dried metal belt is once wound up while peeling off, or continuously passed through a separately provided tunnel-like hot air drying furnace to continuously remove all the film. The remaining solvent is removed by evaporation.
Manufacture PI long film. Here, since it is necessary to carry out the process up to imidation in the case of using PA acid, the temperature range in this case is set to a range of 100 to 450 ° C. Control is performed.

Next, a method of forming an endless tubular A / PI film will be described. First, in order to form an endless tube, a generally known centrifugal molding method is preferably used. That is, molding and heating are performed using the inner peripheral surface of the metal drum that rotates at least at the rotational speed at which the centrifugal force acts. A metal drum with both ends opened (the inner surface is mirror-finished by chrome plating finished to about Rz = 0.5 μm) is mounted (removably) on two rotating rollers. The drum employs a mechanism that rotates indirectly by the rotation of the roller. A heating source (for example, far-infrared ray) for heating the inside of the drum is provided on the upper outside. Here, a heating source is also provided inside the roller,
An auxiliary heating of the drum is provided. Further, a slit-shaped nozzle for discharging a stock solution is provided in the drum, which horizontally moves left and right while being separated from the surface by a predetermined distance, and has a mechanism capable of being inserted and removed. Exit width of this nozzle (slit width)
Is about 0.2 to 3 mm and the length is about 10 to 100 mm. This determines the supply width and supply amount (coating thickness). At least the entire drum is surrounded by a housing having an exhaust fan, so that the organic solvent heated and evaporated during rotational molding can be quickly removed from the system. Of course, a computer is incorporated so that the supply amount of the forming stock solution, the rotation speed of the drum, and the left or right movement speed of the nozzle are automatically controlled so that a desired film thickness can be freely obtained. Have been.

The molding procedure by the molding apparatus is generally performed as follows. First, the nozzle is disposed at a position above the right end of the metal drum at a distance of about 30 to 50 mm. Then, the drum starts rotating at a predetermined rotation speed controlled by the computer. What is important here is that the fine fiber powder A quickly moves so as to be unevenly distributed on the surface portion, and the rotation speed is controlled so that the CB powder is uniformly dispersed throughout as it is. That is. If the rotation speed is too high, a large centrifugal force is applied at a stroke, so that the CB powder also moves to the surface.
Knowing this, it is preferable to perform the rotation at a rotational speed that balances the two through preliminary experiments as appropriate. Preliminary experiments have confirmed that this can be achieved in the range of approximately 5 to 30 rad / s. When the rotation of the metal drum starts, the supply of the forming solution from the slit nozzle starts, and at the same time, the movement of the nozzle from the right end to the left end starts under computer control. Immediately after the supply from the right end to the left end, the injection supply is stopped, and the nozzle is automatically returned to the original position once, further retracted, and taken out of the system. Next, the rotating metal drum is surrounded by a housing, heating by the heating source is started, and the inside of the drum is kept at a predetermined temperature. With the start of the heating, the operation of the exhaust fan of the housing also starts. The rotation speed at this time may be the same as the initial speed, or may be slightly faster or slower (generally, about 0.5 to 2 times the initial speed). The heating condition here is basically a temperature (about 100 to 200 ° C.) higher than the evaporation temperature of the organic solvent but lower than the imidization temperature (about 250 to 450 ° C.). This is because, as described above, one part is not removed without removing all the organic solvent, and imidization is not substantially advanced in the case of using PA acid. In the case of containing and dispersing powder, it also has the meaning of maintaining the stability of the electric resistance value.

After the molding with the metal drum is completed, the drum as it is or the endless tubular film is detached from the drum and put into a separate hot-air dryer to remove the remaining organic solvent and remove the PA. In the case of using an acid, imidization is performed to obtain an endless tubular A / PI film. Therefore, the hot air temperature is
The temperature is in the range of about 100 to 450 ° C., but in any case, it is preferable to gradually increase the temperature in any case, and to heat at that temperature for a certain time. The reason why the hot air is used as the heating medium is to remove the residual solvent generated and the condensed water generated at the time of imidization more quickly than the simple heating. As a result, a conductive metal thin film layer (2
It is said that the adhesive force of B) also becomes stronger and the surface state is also obtained.

The difference between the case where hot air heating is performed with the endless tubular film attached to the metal drum (without detaching the endless tubular film from the metal drum) and the case where heating is performed by detaching the endless tubular film depends on the PI resin as a matrix. . In other words, the resin that tends to shrink as the residual organic solvent evaporates (for example, a PI resin that binds only with a benzene nucleus that does not have an ether bond or the like in the main chain) is once removed and heated, and the other resin is not heated (for example, the main resin). (PI resin having an ether bond or the like in the chain) is to be heated as it is in the drum. The film which is once removed and heated is not inserted into the dryer as it is, but is inserted into a hollow tubular mold (an outer diameter slightly smaller than the inner diameter of the film) to dry the mold. It is better to put it in a machine and heat it. This is to control shrinkage.

The AP obtained by molding as described above
In order to metallize the surface, first, the conductive film B
Thus, the conductive metal thin film layer (2B) is formed. In other words, the thin film layer is formed by a means for forming a physical thin film of the conductive metal B in particular, and this means any of the generally known vacuum deposition method, ion plating method, and sputtering method. In particular, the sputtering method is particularly effective. In other words, by using this means, the adhesion to the film surface is higher than any other means (eg, electroless plating, surface activation by chemical or physical methods), and the performance of the layer itself is improved. Good quality (purity, denseness, low electrical resistance, etc.), and the formation of the conductive metal thick film layer (3) by electrolytic plating, which is another means, is performed smoothly, and the metal thick film with high adhesion is provided. Is easily formed. Here, it is assumed that the effect on the good adhesion to the film surface is due to the following action mechanism. The (active) molecules of the conductive metal B that jumped out at a high speed attack the fine fiber powder A (projecting) existing on the film surface, and are not likely to result in (physical) chemical light bonding. .

The conductive metal B is a simple metal or an alloy thereof, which quickly flows even with a small amount of current, and has an electric resistance of about ^10-4 Ω / □ or less. Specific examples include copper, nickel, silver, platinum, tin, cadmium, aluminum, and alloys containing these as main components. Among them, copper is more preferable in terms of adhesion.
Nickel or aluminum. Here, the reason why conductivity is required is also to use the electrode as an effective electrode in the next electrolytic plating.

The thickness of the thin film layer made of the conductive metal B is a minimum thickness necessary for effectively acting as the electrode, and if the thickness is too thin, the adhesion is adversely affected. It is determined in consideration of the fact that the thin film layer surface should be smooth. From this point, for example, 100 to 1000 nm, preferably 300 to 700 nm
It is.

The forming conditions of each method exemplified by the physical thin film forming means can be performed in a generally used manner. Here, a sputtering method which is mentioned as a preferable method is exemplified. First, when the A / PI film is a long film, it is placed in a vacuum chamber (sputter chamber) of a sputter (cathode is a planar magnetron) device together with a take-up roller in a web wound state. The film surface having the fine fiber powder A on its surface is arranged at a predetermined distance toward the conductive metal B target on the planar. The pressure at the time of sputtering in a vacuum chamber is generally 10 ⁻³ to 10 ⁻¹ Pa by replacing with argon, and the voltage and current at the time of sputtering are 3
^{~15W / cm 2 (DC · 0.2~0.5kv} ) about,
In particular, the sputtering temperature (maintaining temperature in the vacuum chamber) is 80
The temperature is preferably from 160 to 160C, more preferably from 90 to 140C. The sputtering speed (winding speed) is determined by the strength of the voltage and current during sputtering and the desired thickness of the thin film layer (2B). Here, particularly, the reason why the sputtering temperature (maintaining temperature in the vacuum chamber) is set to 80 to 160 ° C. is that the M / PI film is 2
This is because there is no danger that the surface metallized layer will be peeled off even when used at around 00 ° C. That is, it is effective in imparting heat resistance. In particular, since the A / PI film is used, it is not necessary to perform a general pretreatment (chemical or physical treatment), but in order to obtain more secure and reliable adhesion, the pretreatment is performed. Is more desirable. This pretreatment is also preferably a physical method such as plasma discharge treatment or sandblasting rather than chemical treatment. It is considered that the fine fiber powder A on the film surface is damaged by the plasma, which may lead to a further improvement in adhesion.

The sputtering in the case where the A / PI film is an endless tube is preferably performed as follows. First, the conditions of pretreatment, pressure during sputtering, temperature and voltage and current during sputtering are performed within the ranges exemplified above. However, the shape is an endless tubular film, and a plurality of these films are sputtered at a time. A device like this is adopted. First, the vacuum chamber has a vertical drum shape, and one conductive metal B target (cathode) is vertically provided on the inner wall of the drum. On the other hand, a rotating turntable is provided under the drum, and at the outer edge of the table,
A cylindrical body is erected at a constant pitch and at a constant distance from the target. This cylindrical body is for inserting and holding the film, and employs a mechanism that rotates with the rotation of the turntable. With such a structure, the following two operations can be performed to obtain a desired thickness of the conductive metal B thin film layer. One is to make the rotation speed of the cylindrical body constant, and to control the thickness by the rotation (speed and number of rotations) of the turntable. The two control the rotation speed of the turntable and control the thickness by the rotation (speed and rotation speed) of the cylindrical body. Which method is used depends on the relationship with the overall processing efficiency. In the case of at least one endless tubular film, the latter method is adopted.

When glow discharge is performed as a pretreatment, the distance between the cathode and the A / PI film is made short (for example, 10 to 20 mm), unlike sputtering, but the same cathode is used as the target. In some cases, it may not. If the sputter is aluminum, it is preferable to bring another metal B to the cathode. Although the cause is not well understood, there is no effect of improving the adhesion,
Conversely, it can even drop. In this regard, the glow discharge treatment using, for example, chromium as a cathode is effective.

Next, a conductive metal thick film layer (3) is laminated by electroplating on the conductive metal thin film layer (2B) formed on the surface of the A / PI film.
An I film is formed. First, the conductive metal thick film layer (3)
Is a good conductor having a resistance equal to or lower than the electric resistivity of the conductive metal thin film layer (2B), and is efficiently and integrally plated with the metal thin film layer (2B). There is no particular limitation as long as it is a metal, but one preferable condition is that it is the same conductive metal as that of the metal thin film layer (2B) or a better conductor thereof. This is because a better printed circuit or electric induction heat can be generated.
Particularly preferred is a thick film layer of copper or nickel. In order to deposit these metals on the metal thin film layer (2B), an aqueous solution of an inorganic compound of the metal is used as an electrolytic solution.

The thickness of the thick film layer (3) is
B) needs to be formed thicker than that of B) (for example, for the effective development of the printed circuit function or the induction heating function), but being more than necessary means flexibility or the like. It is not preferable because there is a risk of peeling when used in bending. Further, the thickness of the thin film layer also effectively affects the conductivity, so that the thickness of the thick film layer can be set thinner accordingly. From this point, an appropriate range is 1 to 50 μm, preferably 2 to 30 μm.

The electroplating is essentially the same regardless of whether the film has a web shape or an endless tubular shape. The electroplating is carried out using an electroconductive solution containing an electroconductive metal with the electroconductive metal thin film layer (2B) as a base layer serving as a cathode. However, the plating conditions are also in the range generally used. For example, when the metal thick film layer (3) is made of copper, the electrolytic solution is immersed in a plating bath containing copper sulfate and sulfuric acid as main components and a small amount of brightener added thereto, and a bath temperature of about 20 to 40 ° C. , Cathode current density about 1-7
A / dm ² , anode / cathode area ratio 1: 1, air stirring and filtration (vortex state) are always performed. The plating time is appropriately determined by setting conditions in advance. In the case of using nickel, for example, a plating bath containing nickel sulfate, nickel chloride and boric acid as main components is used, and the other conditions are substantially the same as those described above. Before performing the electrolytic plating, the surface of the conductive metal thin film layer (2B) is preferably degreased and cleaned.

The above-mentioned M / PI film has more excellent characteristics than ever before, so that it is more widely used in various fields. For example, it is effectively used as a fixing device member (roll or belt shape) which adopts an electromagnetic induction heating system of a color copying machine, including the field of FPC boards which require finer pattern formation and higher heat resistance. When the film is used as a fixing device member of the color copying machine, the endless tubular film is further subjected to a surface coating treatment with a fluororesin in order to impart higher releasability.

[0041]

The present invention will be described in more detail with reference to the following examples together with comparative examples. The peelability and the coefficient of linear expansion in this example were measured by the following method. ● Removability The obtained endless tubular M / PI film is tensioned at 2N / cm.
And stretched over two rotating rollers (30mm diameter)
Heating to 150 ° C (one of the rotating rollers has a built-in heating source and its temperature is controlled to 150 ° C);
Rotation was continued at a speed of 20 rpm for 5 hours, stopped, and the same place was repeatedly peeled (rapidly peeled) three times with Cellotape (registered trademark), and the presence or absence was checked. ● Linear expansion coefficient (cm / cm / ° C.) Films corresponding to the PI insulating layer and the PI semiconductive layer forming each layer were prepared, and these were used as samples and measured under the following conditions. The measuring device is a thermal analysis system TA-50WS of a thermomechanical analyzer TMA-50 manufactured by Shimadzu Corporation. The sample is 10 mm in length cut in the circumferential direction, and the measurement temperature is 100 to 2 in this length range.
Continuous measurement was performed in the range of 00 ° C while increasing the temperature at a rate of 5 ° C / min. The coefficient of linear expansion at each of the obtained points was averaged and calculated to be the coefficient.

Example 1 First, an equimolar amount of 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride and p-phenylenediamine was subjected to a polycondensation reaction at 20 ° C. in an NMP solvent. Thus, 3 kg of an aromatic PA acid solution 1 (solution viscosity: 1.8 Pa · s) having a solid concentration of 13.5% by weight was synthesized. Then, 1 kg of this was collected, and aluminum borate whiskers (linear expansion coefficient: 4.2 × 10
First, 3.0 g of ⁻⁶ cm / cm / ° C., specific gravity of about 3.6) was preliminarily mixed while stirring with a stirrer equipped with blades, and further transferred to a ball mill to be sufficiently mixed and dispersed. Hereinafter, this is referred to as forming raw material 1. A part of the PA acid solution 1 was collected, cast on a glass plate, heated and dried to remove the solvent and imidize to obtain a polyimide film, and the coefficient of linear expansion was measured. 0.8 to 2.2 × 10 ⁻⁵ c
m / cm / ° C.

The following molding raw material 1 was subjected to centrifugal molding under the following conditions, firstly molded into an endless tubular PA acid film, and the A / PI film having the whisker surface unevenly distributed was obtained.

The conditions for centrifugal molding are as follows. The molding apparatus had the structure described in the text, and the conditions were as follows. ◎ Metal drum ... 450mm width, 360mm inner diameter ◎ Supply amount of forming raw material 1 ... Slowly start the rotation of the drum, and move the slit nozzle from right to left in accordance with the speed. The stock solution 1 was supplied and applied to the entire peripheral surface.回 転 Rotation speed and heating: Heating was started to 120 ° C., and the rotation speed was gradually increased to a speed of 18 rad / s. After the temperature and the speed were reached, the mixture was rotated and heated for 120 minutes. The self-supporting film was formed on the inner peripheral surface of the drum.

Then, the endless tubular PA acid film obtained above was peeled from the metal drum, inserted into a hollow tubular mold having an outer diameter of 353 mm and a width of 400 mm, and placed in a hot-air dryer. To 450 ° C., and further heated at that temperature for 30 minutes. After cooling, the product was taken out of the dryer and removed, and an endless tubular A / PI film was obtained. The thickness of the obtained film is 50 μm, the outer diameter is 353 mm, and a part of the end is cut.
When observed in the above, aluminum borate whiskers were observed on the surface portion (region having a thickness of about 3 μm), but were not seen inside at all.

Then, the obtained A / PI film (cut to a size and width of 360 mm, and having an outer diameter of 353 m)
m) was sputtered on the surface under the following conditions to form a nickel thin film layer 2B. ◎ Sputtering apparatus: As described in the main text, one cylindrical body (outer diameter of 352 m
m, height 370 mm), and the film was fitted thereto. ◎ Sputtering conditions: target is 100mm in width and 3 in length
An 80 mm nickel plate is vertically fixed to the wall surface facing the film, and the degree of vacuum is 10 ⁻³ Torr by replacing with argon.
Sputtering was performed at an output voltage of 6.5 W / cm ^{2 for} 15 minutes while rotating the turntable at a speed of 1 m / min while the temperature in a vacuum chamber was 100 ° C., the distance between the target and the film surface was 15 mm.

A nickel thin film layer 2B was formed very uniformly on the surface of the A / PI film, and the thickness of the layer was measured to be 500 nm. Then, the same place was repeatedly subjected to a peeling test three times with cellophane tape, but no peeling was found.

Next, on the nickel thin film layer 2B of the obtained film, electroplating was carried out under the following conditions to laminate a conductive thick film layer 3 of nickel. A nickel solution of a Watt bath adjusted to a temperature of 30 ° C. is used as an electrolytic solution, and the film supported in a cylindrical shape is immersed in the electrolytic solution to obtain a cathode current density of 5 A / dm ² .
Vortex electrolysis was performed for minutes. When finished, thoroughly wash the whole,
Dried to product. The whole film became slightly stiff, but not stiff enough to cause any problems in bending. The laminated nickel layer was even and uniform, and had a thickness of 20 μm ± 0.5 μm (measured at 20 locations). And both sides of this M ・ PI film are 15mm
They were cut and tested for peelability under the conditions described above. As a result, cellotape peeling was attempted at 20 locations, but no peeling was found. The surface resistivity was 10 ⁻³ Ω.
/ □ digit. The endless tubular M / PI film is illustrated in FIG. Branch number (1b) is a perspective view of the entire film, (1c) is a cross-sectional view of the film taken along the line DD, 1 is an A / PI film having a surface uneven distribution of aluminum borate whiskers 1a, 2B is a nickel thin film layer, and 3 is a nickel thin film layer. This is a nickel thick film layer.

Example 2 An equimolar amount of pyromellitic dianhydride and 4,4′-diaminodiphenyl ether was subjected to a polycondensation reaction in an NMP solvent at 20 ° C. to give a solid concentration of 13.7. 3 kg of a 2% by weight aromatic PA acid solution 2 (solution viscosity: 1.9 Pa · s) was synthesized. And this one
of potassium whisker (linear expansion coefficient: 6.8 × 10 ⁻⁶ cm / c) as fine fiber powder A.
5.0 g of m / ° C., specific gravity of about 3.3) was first preliminarily mixed while stirring with a stirrer equipped with blades, and further transferred to a ball mill to be sufficiently mixed and dispersed. Hereinafter, this is referred to as molding raw material 2. A part of the PA acid solution 2 was sampled, cast on a glass plate, and dried by heating to remove the solvent and imidization to obtain a polyimide film. 0.2 to 2.4 × 10 ⁻⁵ cm / cm /
° C.

The following molding material 2 was subjected to centrifugal molding under the following conditions, firstly molded into an endless tubular PA acid film, and the A / PI film having the whisker surface unevenly distributed was obtained.

The conditions for centrifugal molding were the same as in Example 1. A self-supporting endless tubular PA acid film in the same state as in Example 1 was formed on the inner peripheral surface of the metal drum.

Then, the metal drum was detached from the rotating roller, put into a hot air drier as it was, heated to 400 ° C. in 90 minutes, and further heated at that temperature for 30 minutes. After cooling, it was taken out of the dryer and peeled off to obtain an endless tubular A / PI film. The thickness of the obtained film is 51 μm, the outer diameter is 353 mm, and a part of the end is cut. When this cross section is observed by SEM, a titanic acid is added to the surface (area of about 4 μm in thickness). Potassium whiskers were observed and were not seen inside at all.

Next, the obtained A / PI film (cut to a size and width of 360 mm, and having an outer diameter of 353 m)
m) was sputtered on the surface under the following conditions to form a copper thin film layer 2B. The sputtering was performed in the same manner as in Example 1 except that the target was copper and the output voltage was 6.2 W / cm ² .

A copper thin film layer 2B was formed very uniformly on the surface of the A / PI film, and the thickness of the layer was measured to be 500 nm. And 3 in the same place with cellophane tape
The peel test was repeated several times, but there was no peeling.

Next, the copper thin film layer 2B of the film obtained above
On top, electrolytic plating was performed under the following conditions, and a thick copper layer 3 was laminated. The film supported in a cylindrical shape is immersed in a copper electrolyte adjusted to a temperature of 25 ° C., and the cathode current density is 1 A / d.
Vortex electrolysis was performed at m ² for 7 minutes. When finished, the whole was thoroughly washed and dried to a product. The whole film became slightly stiff, but not stiff enough to cause any problems in bending. The laminated copper layer was even and uniform, and had a thickness of 8 ± 1.0 μm (measured at 20 locations). Then, both sides of this M / PI film were cut by 15 mm, and the peelability was tested. Attempts were made to peel at 20 locations, but no peeling occurred. The surface resistivity was 10 ⁻⁴ Ω / □ digit.

(Example 3) 1 kg of the aromatic PA acid solution 1 obtained in Example 1 was sampled, and 3.0 g of aluminum borate whisker and CB powder (volume resistivity of 10 ^{−) were used. 1} Ω · cm) 20.0 g (12.
7% by weight) was first added with stirring by a stirrer with blades and preliminarily mixed, and then transferred to a ball mill to be sufficiently mixed and dispersed. Hereinafter, this is referred to as forming raw material 3.

Then, the molding raw material 3 was first subjected to centrifugal molding. The centrifugal molding conditions in this case were the same as in Example 1, but the rotation speed of the metal drum was 13 rad / s, and the rotation and heating time was 140 minutes. The self-supporting film was formed on the inner peripheral surface of the drum.

Then, the obtained endless tubular PA acid film was peeled off from the metal drum, inserted into a hollow tubular mold under the same conditions as in Example 1, and heated in a hot-air dryer. After cooling, it was removed from the mold to obtain an endless tubular A / PI film. The obtained film has a thickness of 57 μm and an outer diameter of 35 μm.
3 mm, a part of the end was cut, and this cross section was observed by SEM. Aluminum borate whiskers gathered on the surface as in Example 1, and the CB powder also diffused into the whisker. And it was observed that it was uniformly dispersed throughout the interior. When the surface resistivity (applied voltage: 250 V) of the front surface and the back surface was measured, each was 1.3 × 1
The values were 0 ¹² Ω / □ and 1.1 × 10 ¹² Ω / □. From this, it can be seen that the CB powder is uniformly dispersed throughout.

Then, the surface of the obtained A / PI film (size / width: 360 mm, outer diameter: 353 mm) was sputtered under the following conditions to form a copper thin film layer 2B.
The sputtering conditions were the same as in Example 2 except that the sputtering time was set to 20 minutes. The copper thin film layer 2B was formed extremely uniformly, and the thickness of the layer was measured to be 600 nm. Then, the same place was repeatedly subjected to a peeling test three times with cellophane tape, but no peeling was found.

Next, the thin film layer 2 of copper of the film obtained above
Electrolytic plating was performed on B under the following conditions to laminate a copper thick film layer 3. The electroplating conditions were the same as in Example 2 except that the time was 10 minutes. The copper thick film layer 3 was formed very uniformly without unevenness, and when the thickness of the layer was measured, it was 10 ± 1.3.
μm (average of 20 measurements). And this MP
The peelability of the I-film was also tested in the same manner as in Example 2. Attempts were made to peel the film at 20 locations, but there was no peeling.

(Comparative Example 1) 1 kg of the aromatic PA acid solution 2 obtained in Example 2 was collected, and potassium titanate whiskers were sufficiently mixed and dispersed under the same conditions. , And subsequently heated in the same manner with a hot air drier to complete the desolvation and imidization to obtain an A / PI film having the whisker surface unevenly distributed.

Then, electroless plating of nickel was performed on the entire surface (whisker surface) of the A / PI film under the following conditions. First, the surface of the film was immersed in an aqueous solution of caustic soda (20 g / l) at 90 ° C. for 5 minutes, and then sufficiently washed with water and dried to perform a surface pretreatment. Next, this was immersed in an aqueous solution containing palladium chloride, tin chloride and hydrochloric acid as main components at room temperature for 10 minutes, pulled up, sufficiently washed with water and dried, and further immersed in an aqueous hydrochloric acid solution (to remove tin). Palladium is adhered to this surface and serves as a catalytically active nucleus for the subsequent electroless operation.

Then, nickel sulfate, sodium hypophosphite and ammonium citrate were used as an electroless plating bath at a temperature of 35%.
° C, and add the treated A / PI film to this
Soak for minutes. It was thoroughly washed and dried.

Next, the obtained nickel electroless plating layer was used as a cathode, and immersed in a nickel solution of a Watt bath under the same conditions as in Example 1 to perform nickel electroplating. The thickness of the laminated nickel layer was 24.7 ± 3.7 μm.

When the same peeling test as in Example 1 was performed on the obtained tubular film, 30 hours after the start of rotation.
The test was stopped because the nickel layer was partially peeled off in minutes and almost completely peeled off in 60 minutes. Looking at the state of isolation, peeling was found between the substrate (A / PI film) and the nickel electroless layer.

Example 4 (Example of Electromagnetic Induction Heating Test) First, using the molding raw material 3 prepared in Example 3, centrifugal molding → hot-air drying → copper sputtering → copper electroplating according to the example. The same copper metallized M / PI endless tubular film as in the example was obtained.

On the other hand, a copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether (having a melting point of about 30)
5 ° C), melt-extruding from a circular die (temperature 380 ° C) while innerizing (temperature 80 ° C) (stretching 1.1 times in the machine direction), thickness 60 ± 7μm, inner diameter 3
A 55 mm endless tubular fluororesin film was formed.

Then, the copper metallized M / PI endless tubular film was fitted into the hollow tubular mold used in Example 1, and the endless tubular fluororesin film was attached thereon, and the vacuum hot air dryer was used. And heated at 120 ° C. for 30 minutes. By this vacuum heating, the fluororesin film could be firmly contracted and adhered without oxidizing the copper layer and eliminating oxygen. The temperature is further raised to 360 ° C.
Heated for minutes. It was cooled to room temperature and taken out of the dryer. The fluororesin film was firmly melt-adhered to the copper layer surface of the M / PI endless tubular film. Hereinafter, it is referred to as a fluororesin-coated PI film.

Then, the fluororesin-coated PI film was installed in a belt rotating state, an electromagnetic induction heating coil was arranged in the belt, and a power of 120 W was applied to measure the surface temperature of the belt. As a result, heat is generated immediately and 160 ° C
Reached and became constant. It was also confirmed that heat was generated effectively by the electromagnetic induction. Here, the reason why this test was carried out with the fluororesin applied was that the toner fixing was also required to have releasability from paper, so that it was performed under the condition that the function was imparted. . Although there are various methods for coating the resin, the present method using a preformed tube is more effective.

[0070]

According to the present invention, as described above, a PI-based film in which a specific substance is unevenly dispersed on the surface is combined with a physical thin-film method such as sputtering and an electrolytic plating method to obtain a surface conductive film. The metalized film has the following effects.

The adhesion between the surface conductive metallization layer and the surface of the PI film could be greatly improved. This adhesion is, of course, when the film is flat, but in particular, it is endless tubular, and has an adhesion that has been improved to a practical level even when used under heating while rotating the belt. There are.

Although the specific substance is mixed and dispersed in the metallized PI film, since the dispersed state is a surface portion, the specific characteristics are not reduced without deteriorating the essential characteristics of the PI film itself. Configuration can be taken.

Since the conductive thin film layer formed by sputtering or the like is formed with high performance and high quality, the conductive layer formed by electrolytic plating can be formed thinner. For example, when used as an FPC board, the line width of a circuit can be made thinner, which leads to more circuit integration.

[Brief description of the drawings]

FIG. 1 is a perspective view (1b) of an endless tubular M / PI film and a DD sectional view (1c) thereof in Example 1.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Aluminum borate whisker 1a Endless tubular PI film unevenly distributed on the surface 2B Nickel thin film layer 3 Nickel thick film layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) C23C 28/02 C23C 28/02 C25D 5/56 C25D 5/56 B 7/00 7/00 J H05K 1 / 03 610 H05K 1/03 610N F-term (Reference) 4F071 AA60 AB18 AB20 AB26 AB27 AD01 AF54 AF62 AH13 BA02 BB02 BC01 BC17 4F100 AA01A AA01H AA16A AA16H AA19A AA19H AA31A AA31H AABAB ABB AB17AB13A BA07 BA10A BA10C DA11 DE01A DE01H DG01A DG01H EH66B EH71C GB41 GB43 JA02A JA02H JA20B JA20C JG01 JG01A JG01B JG01C JM02B YY00A YY00B YY00C YY00B YY00C YY00B 4J002 CM041 ABA14G02 A006 BAK4A BB03 BC05 CA13 CA18

Claims (10)

[Claims] 1. A polyimide film (1) in which fine fibrous inorganic compound powder A having a linear expansion coefficient equal to or less than that of a polyimide resin is unevenly distributed on a surface portion, and said film is provided. The surface of the conductive metal thin film layer (2B) formed by the physical thin film forming means of the conductive metal B and the conductive metal thick film layer (3) formed by the electrolytic plating method are successively adhered and laminated. A metallized polyimide film characterized by the above-mentioned. 2. The metallized polyimide film according to claim 1, wherein said fine fibrous inorganic compound powder A is a whisker-like inorganic compound powder having a specific gravity of 2.5 to 4. 3. The method according to claim 1, wherein the fine fibrous inorganic compound powder A is at least one selected from the group consisting of whisker-like potassium titanate, aluminum borate, silicon carbide, silicon nitride, and alumina. Metallized polyimide film. 4. The metallized polyimide film according to claim 1, wherein the fine fibrous inorganic compound powder A is contained in an amount of 2 to 10% by weight based on the polyimide resin. 5. The metallized polyimide film according to claim 1, wherein said polyimide film (1) is an endless tubular polyimide film. 6. The metallized polyimide film according to claim 5, further comprising a conductive carbon black powder in a substantially uniform dispersion state in the endless tubular polyimide film. 7. The metallized polyimide film according to claim 6, wherein said conductive carbon black powder is contained in an amount of 5 to 15% by weight based on the polyimide resin. 8. The method according to claim 1, wherein said conductive metal B is made of copper, nickel or aluminum, and said conductive metal thick film layer (3) is made of one of copper and nickel. Metallized polyimide film. 9. The method according to claim 1, wherein said physical thin film forming means is 80 to 160 ° C.
The metallized polyimide film according to any one of claims 1 to 8, which is formed by a sputtering method using a conductive metal B as a target below. 10. The conductive metal thin film layer (2B) has a thickness of 100 to 1000 nm, and the conductive metal thick film layer (3) has a thickness of 1 to 50 μm. 2. The metallized polyimide film according to item 1.