JP2006187963A - Method and apparatus for manufacturing polyimide multilayered film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve the excellent adhesion between respective polyimide layers and the enhancement of productivity, in manufacturing a polyimide multilayered film by forming a gel film having a multilayered structure (multilayered gel film) to heat-treat the same. <P>SOLUTION: A plurality of kinds of polyimide varnishes, each of which contains polyimide or polyamic acid being a polyimide precursor, are laminated on a support to form a multilayered liquid film which is, in turn, dried to obtain the multilayered gel film. In this case, a dehydration agent and a catalyst are preliminarily added to at least one kind of the varnish and the drying of the multilayered gel film is preferably started within 2 min before the ply separation of the multilayered gel film. It is more preferable to preliminarily cool the varnishes to the normal temperature or below. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention has a plurality of polyimide layers made of a resin composition containing polyimide, and can be suitably used in a method for producing a polyimide-based multilayer film having good adhesion of each polyimide layer, and this production method. The present invention relates to an apparatus for producing a polyimide-based multilayer film, for example, the production of a multilayer film such as an adhesive film including a structure in which an adhesive layer containing a thermoplastic polyimide is provided on at least one surface of a film containing a heat-resistant polyimide. The present invention relates to a manufacturing method and a manufacturing apparatus that can be suitably used for the manufacturing method.

  In recent years, the demand for various printed circuit boards has increased with the reduction in weight, size and density of electronic products. Among these printed boards, the demand for flexible wiring boards is growing. The flexible wiring board is also referred to as a flexible printed wiring board (FPC). The flexible wiring board has a structure in which a circuit made of a metal layer is formed on an insulating film.

  The above-mentioned flexible wiring board is generally formed of various insulating materials, a flexible insulating film is used as a substrate, and a metal foil is bonded to the surface of the substrate by heating and pressure bonding via various adhesive materials. Manufactured by. A polyimide film or the like is preferably used as the insulating film, and an epoxy or acrylic thermosetting adhesive is generally used as the adhesive material. A flexible wiring board using such a thermosetting adhesive has a three-layer structure of substrate / adhesive material / metal foil, and is hereinafter referred to as “three-layer FPC” for convenience of explanation.

  The thermosetting adhesive used for the three-layer FPC has an advantage that it can be bonded at a relatively low temperature, but has relatively low heat resistance and poor electrical characteristics. Therefore, in the future, it is assumed that requirements for various characteristics such as heat resistance, flexibility, and electrical reliability will become stricter for flexible wiring boards. However, in a three-layer FPC using a thermosetting adhesive, It is considered difficult to sufficiently meet such demands.

  On the other hand, a flexible wiring board in which a metal layer is directly provided on an insulating film and a flexible wiring board using a thermoplastic polyimide as an adhesive layer have been proposed. Since these flexible wiring boards are in a state in which a metal layer is directly formed on an insulating substrate, they are hereinafter referred to as “two-layer FPC” for convenience of explanation. This two-layer FPC has characteristics superior to those of the three-layer FPC because a polyimide resin having excellent heat resistance, flexibility, electrical reliability, and the like is used as a main component of the substrate (base material). Therefore, it is industrially useful because it can sufficiently meet the demands for the various characteristics described above, and demand is expected to grow in the future.

  The two-layer FPC is manufactured using a flexible metal-clad laminate having a structure in which a metal foil is laminated on a substrate. Examples of the method for producing the flexible metal-clad laminate include a casting method, a metalizing method, and a laminating method. The casting method is a method in which an organic solvent solution of polyimide or its precursor polyamic acid (referred to as “polyimide varnish” for convenience) is cast on a metal foil, and then imidized. The metalizing method is a method in which a metal layer is directly provided on a polyimide film by sputtering or plating. The laminating method is a method of bonding a polyimide film and a metal foil through a thermoplastic polyimide layer.

  Among these, the laminating method is superior in that the thickness range of the metal foil that can be handled is wider than that of the casting method, and the cost required for the apparatus is lower than that of the metalizing method. As an apparatus for performing the laminating method, a hot roll laminating apparatus or a double belt press apparatus for continuously laminating a roll-shaped material is used.

  In the flexible metal-clad laminate produced by the above laminating method, as a substrate, a layer of a resin composition containing thermoplastic polyimide on at least one surface of a polyimide film (heat-resistant polyimide layer) mainly composed of heat-resistant polyimide An adhesive film provided with a (thermoplastic polyimide layer) is widely used. In this adhesive film, the heat-resistant polyimide layer becomes an insulating film, and the thermoplastic polyimide layer becomes an adhesive layer. In other words, this adhesive film can be referred to as a polyimide film having a multilayer structure (polyimide multilayer film).

  Typical methods for producing the polyimide multilayer film include a coating method, a heat laminating method, a casting film forming method, and the like. The coating method is a method in which a solution of a resin composition containing a thermoplastic polyimide or a precursor thereof is applied to one or both sides of a polyimide film to be a heat-resistant polyimide layer and dried. The thermal laminating method is a method in which a polyimide film containing thermoplastic polyimide as a main component is heated and bonded to one side or both sides of a polyimide film to be a heat resistant polyimide layer.

  Examples of the casting film forming method include a sequential method (sequential coating method) and a coextrusion method (coextrusion casting film forming method). The sequential method includes a solution of a resin composition containing a heat-resistant polyimide or a precursor thereof (referred to as “heat-resistant polyimide varnish” for convenience) and a solution of a resin composition containing a thermoplastic polyimide or a precursor thereof ( For the sake of convenience, this is referred to as “thermoplastic polyimide varnish”) on the support. The coextrusion method is a method in which both a heat-resistant polyimide varnish and a thermoplastic polyimide varnish are simultaneously formed on a support by using a coextrusion die (see, for example, Patent Documents 1 and 2).

  In the manufacturing method of the said polyimide-type multilayer film, generally it passes through the process of imidating after making a polyimide-type varnish into a gel film. In this gel film, a liquid film made of a polyimide varnish is made into a gel state having a self-indicating property by a treatment such as heat drying or partial imidization.

  For example, in the above-described coating method, first, a dehydrating agent, a catalyst, or the like is added to the heat-resistant polyimide varnish and reacted to obtain a gel film that is not completely imidized. A thermoplastic polyimide varnish is applied to at least one surface of the gel film, and then dried and heated. Thereby, the polyimide-type multilayer film by which the thermoplastic polyimide layer was formed in the surface of the heat resistant polyimide layer used as a center layer is obtained (for example, refer patent documents 3 and 4).

  In the casting film forming method, first, a liquid film made of a heat-resistant polyimide varnish or a thermoplastic polyimide varnish is formed on a support such as a metal belt or a metal roll. And these liquid films are made into the gel film which has the self-supporting property by heat-drying. This gel film has a multi-layer structure by either sequential method or coextrusion method. Thereafter, the gel film having a multilayer structure (multilayer gel film) is peeled off from the support and further imidized by heat treatment at a high temperature. Thereby, a polyimide-type multilayer film can be obtained.

Among the manufacturing methods described above, the coextrusion method can form a multi-layered liquid film (multi-layer liquid film) at a time and requires fewer steps. This has the advantage of high productivity and product yield. In addition, it is known that in the coating method, it is difficult to firmly adhere between the polyimide layers in the obtained polyimide-based multilayer film, and it is often impossible to obtain an adhesive film having sufficient adhesive strength. Yes. Therefore, when producing a polyimide-based multilayer film, it is preferable to employ a casting film forming method, particularly a coextrusion method (coextrusion casting film forming method).
No. 2946416 (Registered July 2, 1999 (1999), publication number: JP-A-11-99554, publication date: April 13, 1999 (1999)) Japanese Patent Laid-Open No. 7-214636 (published August 15, 1995) JP-A-8-244168 (published September 24, 1996) JP 2001-139807 A (published on May 22, 2001)

  However, when the above-described coextrusion casting film forming method is employed as a method for producing a polyimide-based multilayer film, there remain problems to be solved in practice.

  Specifically, when a multilayer gel film is to be obtained by a coextrusion method, a heat-resistant polyimide varnish or a thermoplastic polyimide varnish is laminated as it is to form a liquid film, which is dried. However, in this case, since the thickness of the liquid film is large, the time until gelation becomes long or the time for imidization treatment becomes long, and the multilayer gel film is firmly attached to the surface of the support. This causes a problem that the gel film becomes difficult to peel off. These problems reduce the productivity and product yield of polyimide multilayer films.

  The present invention has been made in view of the above problems, and its purpose is to produce a multilayer multilayer film by producing a multilayered gel film (multilayer gel film) and heat-treating it. The object is to provide a technique capable of improving productivity as well as improving adhesion between layers.

  As a result of intensive studies in view of the above problems, the present inventors have added a dehydrating agent and a catalyst to a polyimide varnish to cause gelation (adopting a chemical imide method), thereby increasing the gelation rate of the multilayer liquid film. In addition, the present inventors have uniquely found that it is possible to improve the peelability of the gel film from the support and to improve productivity and product yield.

  However, when the chemical imide method is employed, in the resulting multilayer gel film, the adhesion between the gel films is reduced, and it has also been clarified that the gel films peel from each other. This is because when a multilayer liquid film undergoes a gelation reaction, water, solvent, dehydrating agent, catalyst, etc. generated by the reaction are discharged out of the system (outside the liquid film). It turned out to be to accumulate.

  Therefore, as a result of further earnest studies, the present inventors have completed the gelation before forming a multilayer liquid film and then peeling between the liquid films, thereby providing a multilayer gel film having high interlayer adhesion. The inventors have independently found that the present invention can be obtained, and have completed the present invention.

  That is, it is a manufacturing method of the polyimide-type multilayer film which has two or more polyimide layers which consist of the resin composition containing the polyimide concerning this invention, Comprising: The organic solvent solution containing a polyimide or its precursor is several types on a support body A multilayer liquid film forming step for forming a multilayer liquid film by laminating and a gel film forming step for obtaining a self-supporting multilayer gel film by drying and gelling the multilayer liquid film. Furthermore, a dehydrating agent and a catalyst are added in advance to at least one of the organic solvent solutions used in the multilayer liquid film forming step, and the layers of the multilayer liquid film are separated in the gel film forming step. It is characterized by starting the drying of the multilayer liquid film before.

  In the multilayer liquid film forming step, it is preferable to form a multilayer liquid film by a coextrusion casting film forming method in which a plurality of types of organic solvent solutions are simultaneously extruded and cast on a support.

  In the gel film forming step, drying is preferably started within 2 minutes from the time when the multilayer liquid film is formed on the support, and within 30 seconds from the time when the multilayer liquid film is formed on the support. More preferably, the drying is started. Moreover, in the said gel film formation process, it is preferable to make the temperature at the time of drying a multilayer liquid film into the range of 60-200 degreeC.

  In the manufacturing method, the plurality of polyimide layers include a heat-resistant polyimide layer made of a resin composition containing a heat-resistant polyimide and a thermoplastic polyimide layer made of a resin composition containing a thermoplastic polyimide. In the multilayer liquid film forming step, it is preferable to form the multilayer liquid film so that the liquid film to be the thermoplastic polyimide layer is in contact with at least one surface of the liquid film to be the heat resistant polyimide layer. In this case, it is particularly preferable to add a dehydrating agent and a catalyst only to the organic solvent solution that becomes the heat-resistant polyimide layer.

  Furthermore, in the said manufacturing method, it is more preferable to include the solution cooling process which cools the said organic solvent solution below normal temperature before the said multilayer liquid film formation process. In this solution cooling step, the organic solvent solution is preferably cooled to 10 ° C. or lower, and the lower limit of the cooling temperature of the organic solvent solution is preferably −10 ° C. Therefore, the cooling temperature of the organic solvent solution in the solution cooling step is more preferably within a range of −10 to 10 ° C.

  An apparatus for producing a polyimide-based multilayer film according to the present invention is an apparatus for producing a polyimide-based multilayer film having a plurality of polyimide layers made of a resin composition containing polyimide, and an organic solvent solution containing polyimide or a precursor thereof. Solution supply means for supplying while cooling, discharge means for discharging the organic solvent solution supplied from the solution supply means in the form of a liquid film, and support for casting the liquid film of the organic solvent solution discharged from the discharge means A body, and a drying means for gelling the liquid film on the support to form a gel film having self-supporting property, and a firing means for firing to imidize the gel film, Furthermore, a plurality of the solution supply means are provided so that a plurality of types of organic solvent solutions can be supplied, and at least one solution supply means is provided. The organic solvent solution containing the dehydrating agent and the catalyst can be supplied in advance, and the discharging means can form the multilayer liquid film formed by laminating a plurality of liquid films on the support. While the solvent solution is discharged, the drying means starts drying the multilayer liquid film before the layers of the multilayer liquid film are separated.

  It is preferable that the discharge means is capable of simultaneously discharging liquid films of a plurality of types of organic solvent solutions onto the support, and the discharge means is more preferably a coextrusion die.

  The support is preferably a rotator, and more preferably a belt-like support that is rotatably supported by a plurality of rotating shafts.

  The drying means is preferably a heating furnace that heats the multilayer liquid film in a state where the multilayer liquid film on the support is carried in. At this time, the support preferably carries the multilayer liquid film formed by the discharge means into the heating furnace within 2 minutes after the formation. Furthermore, it is preferable that the distance from the discharge means to the heating furnace and / or the rotation speed of the support is set so that the multilayer liquid film can be carried into the heating furnace within 2 minutes after formation.

  The firing means is preferably a firing furnace for firing the gel film in a state where the gel film peeled off from the support is carried in.

  As described above, in the present invention, when producing a polyimide-based multilayer film, a dehydrating agent and a catalyst are added to at least one of the liquid films forming the multilayer liquid film. The drying process is performed before the layers are separated.

  In the present invention, the gelation or imidization of the liquid film proceeds smoothly by using a dehydrating agent and a catalyst, but the water, solvent, dehydrating agent and catalyst produced by the reaction are out of the system (outside the liquid film). It will be discharged. Since these are discharged between the liquid films, the liquid films are easily separated by these components. However, in the present invention, before the separation of the liquid film becomes significant (before the layers are separated), the drying process is quickly started. Therefore, in the multilayer gel film obtained, the adhesiveness between layers becomes high.

  Such a multilayer gel film is excellent in peelability from the support, and if this is further fired, in the resulting polyimide-based multilayer film, the adhesion of each polyimide layer is improved. be able to. As a result, there is an effect that a polyimide-based multilayer film excellent in interlayer adhesion can be produced.

  One embodiment of the present invention will be described below with reference to FIGS. 1 to 4, but the present invention is not limited to this. The present invention can be carried out in a mode in which various improvements, modifications and variations are added based on the knowledge of those skilled in the art without departing from the spirit of the present invention.

(I) Production method of polyimide multilayer film The present invention is a technique for producing a multilayer film (polyimide multilayer film) of two or more layers comprising at least two or more types of polyimide compounds (polyimide-containing resin composition). is there.

  Specifically, in the present invention, first, the solution of two or more kinds of polyimide compounds (polyimide varnish) is cooled to −10 to 10 ° C. Next, after adding a chemical dehydrating agent (dehydrating agent) and a catalyst to a solution of at least one polyimide compound selected from the solutions of the two or more polyimide compounds, the two or more polyimide compounds A liquid film (multilayer liquid film) having a multilayer structure in which the above solutions are laminated is formed on a substrate (support). Next, the multilayered liquid film is heated and dried to remove the solvent before the time for delamination of the multilayered liquid film, thereby obtaining a multilayered gel film (multilayered gel film). And this is heat-processed and imidation is completed.

  The present invention is achieved by combining at least the addition of a dehydrating agent and a catalyst and the gelation treatment before delamination between layers in the formation of a multilayer liquid film among the above processes, and further cooling the polyimide varnish. As a result, the functions and effects of the present invention can be further improved. In particular, in the present invention, the method for forming a liquid film having a multilayer structure is preferably a coextrusion casting film forming method.

  In the method for producing a polyimide-based multilayer film according to the present invention (sometimes simply abbreviated as a multilayer film for convenience of explanation), if the production method is classified into steps, the step of preparing the polyimide-based varnish (varnish) Preparation step), a step of adding a dehydrating agent and a catalyst to the polyimide varnish (curing agent addition step), a step of cooling the polyimide varnish (varnish cooling step), and a multilayer on the support using the polyimide varnish. A step of forming a liquid film (multilayer liquid film forming step), a step of drying the obtained multilayer liquid film to obtain a multilayer gel film (gel film forming step), and baking the resulting multilayer gel film for imidization It can be divided into a process to be completed (firing process). Hereinafter, the production method will be specifically described based on the above-mentioned division of each process.

<Varnish preparation process>
The varnish preparation step is a step of preparing a polyimide varnish that is a solution of a polyimide compound. Here, the polyimide-based compound refers to a polyimide or its precursor polyamic acid (polyamic acid), and further a resin composition containing at least one of these, and a solution obtained by dissolving this in an organic solvent. This is called a polyimide varnish.

  In general, it is known that polyimide has low solubility in various organic solvents and it is difficult to prepare a solution. On the other hand, polyamic acid can be dissolved in a relatively wide variety of organic solvents. Therefore, in the present invention, the polyamic acid, which is a polyimide precursor, can be dissolved in an appropriate organic solvent and used. In the present invention, when the polyimide or polyamic acid is made into a solution, other components may be added. Therefore, the “polyimide compound” in the present invention includes polyimide, polyamic acid, and a resin composition containing at least one of these.

  The organic solvent used in the polyimide varnish is not particularly limited as long as it is an organic solvent capable of dissolving the polyimide compound. Specifically, for example, sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide are used. A formamide solvent such as N, N-dimethylformamide and N, N-diethylformamide; an acetamide solvent such as N, N-dimethylacetamide and N, N-diethylacetamide; N-methyl-2-pyrrolidone and N-vinyl Pyrrolidone solvents such as 2-pyrrolidone; phenol solvents such as phenol, o-, m-, or p-cresol, xylenol, halogenated phenol, catechol; ether solvents such as tetrahydrofuran, dioxane, dioxolane; methanol, ethanol , Butanol It can be mentioned organic polar solvent, such as; the alcoholic solvent; cellosolve solvents such as butyl cellosolve; hexamethylphosphoramide, solvents such as γ- butyrolactone. These organic solvents may be used alone or in combination of two or more. Furthermore, aromatic hydrocarbons such as xylene and toluene can also be used.

  Among the above organic solvents, formamide solvents such as N, N-dimethylformamide (DMF) and N, N-diethylformamide (DMAc) can be particularly preferably used. In addition, since the water content in the organic solvent promotes the decomposition of the polyamic acid, it is preferable to remove water from the organic solvent as much as possible.

  As described above, generally, polyimide often has low solubility in various organic solvents. Therefore, when the polyimide to be used has sufficient solubility with respect to the organic solvent, it may be used as a polyimide varnish by dissolving the polyimide as it is in the organic solvent. On the other hand, when the polyimide to be used does not have sufficient solubility in an organic solvent, it may be used as a polyimide varnish by dissolving the polyamic acid, which is a precursor of the corresponding polyimide, in the organic solvent.

  The polyimide used in the present invention or the polyamic acid that is a precursor thereof is not particularly limited as long as it is a compound having a polyimide skeleton or a polyamic acid skeleton, and a conventionally known one can be used. Specifically, for example, a precursor (polyamic acid) obtained by dissolving and polymerizing an acid dianhydride component and a diamine component in a polymerization solvent, and dehydrating the polyamic acid chemically or thermally. And polyimide obtained by imidization.

  As the polymerization solvent, the above-described organic solvent for preparing a varnish can be suitably used. For example, if an organic solvent such as DMF or DMAc is used as a polymerization solvent, the resulting organic solvent solution of polyamic acid (polyamic acid solution) can be used almost directly as a polyimide varnish.

  The acid dianhydride component and the diamine component are not particularly limited, and known compounds can be used. Typically, a combination of pyromellitic anhydride and diaminophenyl ether may be mentioned, but other acid dianhydrides and diamines may be used in combination or in combination as required. These compounds may be copolymerized.

  The details of the polyimide, polyamic acid and the monomer raw materials (acid dianhydride component and diamine component) that are preferably used in the present invention are more specifically described in (II) Polyamic acid synthesis described later. explain.

<Curing agent addition process>
The said hardening | curing agent addition process is a process of adding a chemical dehydrating agent (dehydrating agent) and a catalyst with respect to at least 1 sort (s) of the polyimide-type varnish prepared at the said varnish preparation process. These dehydrating agents and catalysts are collectively referred to as curing agents. That is, in the present invention, at least one polyimide layer is imidized by the chemical imide method.

  The dehydrating agent used in the present invention is not particularly limited as long as it is a dehydrating ring-closing agent for polyamic acid. Specifically, for example, as a main component, an aliphatic acid anhydride, an aromatic acid anhydride, etc. , N, N′-dialkylcarbodiimide, lower aliphatic halides, halogenated lower aliphatic acid anhydrides, arylsulfonic acid dihalides, thionyl halides, and the like. These compounds may be used alone or in combination of two or more. Among these, aliphatic acid anhydrides and / or aromatic acid anhydrides can be particularly preferably used.

  Although the usage-amount of the said dehydrating agent is not specifically limited, In the polyimide-type varnish used as addition object, it exists in the range of 0.5-5 mol per mol of amic acid unit contained in the polyamic acid contained. The range of 0.7 to 4 mol is more preferable, and the range of 1.5 to 2.5 mol is particularly preferable.

  The catalyst used in the present invention is not particularly limited as long as it is a component having an effect of accelerating the dehydration ring-closing action of the dehydrating agent on the polyamic acid. Specifically, for example, an aliphatic tertiary amine is used. , Aromatic tertiary amines, heterocyclic tertiary amines, and the like. Among these, for example, nitrogen-containing heterocyclic compounds such as imidazole, benzimidazole, isoquinoline, quinoline, diethylpyridine, and β-picoline are particularly preferably used.

  The amount of the catalyst used is preferably in the range of 0.05 to 3 moles per mole of amic acid unit contained in the polyamic acid contained in the polyimide varnish to be added, and 0.2 to 2 moles. The range is more preferable, and the range of 0.5 to 1 mol is particularly preferable.

  When the usage-amounts of the said dehydrating agent and a catalyst are less than the said range, imidation may become inadequate and it may fracture | rupture in the middle of baking or mechanical strength may fall. Moreover, when these amounts exceed the above range, the progress of imidization becomes too fast, and it may be difficult to cast the polyimide varnish into a film.

  In the present invention, it is essential to add the dehydrating agent and the catalyst (curing agent) to one or more of a plurality of types of polyimide varnishes. If the curing agent is added in this way, the gelation reaction can be promoted when the polyimide varnish is formed into a liquid film and dried, and the gelation reaction is accelerated to generate out of the system by a curing agent or reaction. Water, organic solvent, etc. are discharged.

  Specifically, the gel film is a gel film in which the liquid film has self-supporting property by heating and / or drying a polyimide varnish. In this gel film, at least an organic solvent remains, and in particular, when the resin content in the varnish is polyamic acid, a part of the polyamic acid is imidized. Furthermore, in the curing agent addition step, since the curing agent is added, a part of the curing agent itself remains, or a part of the water generated with the reaction remains. Such organic solvent, water, curing agent, and the like are collectively referred to as residual components. These remaining components ooze out from the inside of the liquid film or gel film as the gelation proceeds. This is because gelation proceeds rapidly in a system to which a curing agent is added.

  The residual component discharged in this way accumulates in the gap between the gel film and the support, thereby making it easier to peel off the gel film from the support. Therefore, if a curing agent is added, gelation and imidization are promoted, and the peelability of the gel film can be improved. As a result, the productivity of the multilayer film can be increased. On the other hand, when the curing agent is not added, the gelation reaction rate is slowed down, not only the productivity is lowered, but also the gel film is firmly adhered to the support, so that it can be peeled off. Decreases. Therefore, improvement in productivity of the multilayer film may be hindered.

  The method for adding the curing agent to the polyimide varnish is not particularly limited as long as the curing agent can be sufficiently dispersed or dissolved in the polyimide varnish. Generally, the curing agent is dispersed or dissolved in the same organic solvent as that used for the polyimide varnish in advance to prepare a curing agent solution, which is added to the polyimide varnish and mixed. Methods can be mentioned (see examples).

  In this method, since the viscosity of the polyimide varnish is high, there is an advantage that the curing agent is easily dispersed or dissolved rather than adding the curing agent to the polyimide varnish as it is. Furthermore, since the curing agent can be handled substantially as a liquid, as described later, there is an advantage that the curing agent can be easily supplied in the multilayer film manufacturing apparatus according to the present invention.

<Varnish cooling process>
The varnish cooling step is a step of cooling the polyimide varnish obtained in the varnish preparation step or the polyimide varnish to which the curing agent is added in the curing agent addition step to below room temperature.

  In the present invention, as described above, a multilayer liquid film is formed after adding a curing agent (dehydrating agent and catalyst) to at least one polyimide varnish. For this reason, if the gelling reaction proceeds before the multilayer liquid film is formed, it is difficult to produce the multilayer liquid film to have a desired structure. Therefore, if the polyimide varnish is cooled to below room temperature, the progress of the gelation reaction can be suppressed.

  The normal temperature here is a normal temperature that is not heated and cooled, and is usually about 15 ° C., but is not necessarily limited to this temperature, and in the method for producing a multilayer film according to the present invention. The temperature of the environment where the work is carried out without cooling can be regarded as “normal temperature”. Therefore, in the varnish cooling step, the polyimide varnish may be cooled at least so as to be lower than the temperature of the working environment.

  Thus, the temperature for cooling the polyimide varnish is not specifically limited, but preferably the polyimide varnish is preferably cooled to 10 ° C. or lower, and preferably cooled to 5 ° C. or lower. More preferred. If the upper limit of the cooling temperature is the above temperature, the progress of gelation can be suppressed regardless of the type of polyimide, polyamic acid, or curing agent.

  On the other hand, the lower limit of the cooling temperature is preferably −10 ° C., more preferably −5 ° C. That is, in the varnish cooling step, the polyimide varnish is preferably cooled to −10 ° C. or higher and 10 ° C. or lower, and more preferably −5 ° C. or higher and 5 ° C. or lower. If the temperature of the polyimide varnish is too low, the viscosity of the polyimide varnish becomes too high, and the miscibility with the curing agent deteriorates or film formation becomes impossible.

  Here, the varnish cooling step may be performed before the multilayer liquid film forming step described later, but is preferably performed before the curing agent addition step. When adding a hardening | curing agent to a polyimide-type varnish, if the polyimide-type varnish is cooled before addition, the progress of gelatinization before film forming can be suppressed more reliably. Furthermore, in the varnish cooling step, it is more preferable to cool the hardener (or hardener solution) to be added so that it is less than room temperature. Thereby, since the temperature of the curing agent to be added is also low, it is possible to effectively avoid a situation in which the temperature of the cooled polyimide varnish rises due to the addition of the curing agent.

  The method for cooling the polyimide varnish and the curing agent (curing agent solution) is not particularly limited, and a conventionally known cooling method can be suitably used depending on the production equipment. For example, in a multilayer film manufacturing apparatus described later, a polyimide varnish and a curing agent solution are sequentially supplied in a state where they are accumulated in a tank, and this tank may be equipped with a known cooling device.

<Multilayer liquid film formation process>
The multilayer liquid film forming step is a step of forming a multilayer liquid film by laminating a plurality of types of polyimide varnishes on a support. Here, the formation method of the multilayer liquid film is not particularly limited, and the respective liquid films may be sequentially formed and laminated by a casting coating method, or the respective liquid films may be formed simultaneously. Especially, in this invention, it is preferable to form a multilayer liquid film by the coextrusion casting film forming method which extrudes and casts multiple types of organic solvent solution simultaneously on a support body.

  In the coextrusion casting film forming method (coextrusion method), a plurality of types of polyimide varnishes are simultaneously discharged and cast on a support to form a multilayer liquid film substantially in one step. Therefore, not only can the increase in the number of steps be avoided, but also the time for forming a multilayer liquid film can be shortened compared with the method of sequential lamination (sequential method). Accumulation in can also be avoided.

  The support is not particularly limited and is not dissolved by the polyimide varnish, and preferably has excellent gel film peelability, but is made of various metals. A thing can be used suitably. In particular, when the gel film is heated together with the support in the subsequent baking step, a metal support having durability against heating is preferably used. The means for forming the multilayer liquid film on the support is not particularly limited as long as it can discharge the polyimide varnish onto the support (discharge means), but preferably uses a coextrusion die. be able to.

  In addition, the more specific structure of the said support body and a discharge means is demonstrated in detail in the term of the manufacturing apparatus of the (III) multilayer film mentioned later.

<Gel film formation process>
The gel film forming step is a step of obtaining a self-supporting multilayer gel film by drying and gelling the multilayer liquid film formed in the multilayer liquid film forming step. In particular, in the present invention, a dehydrating agent and a catalyst (curing agent) are added in advance to at least one of a plurality of types of polyimide varnishes used in the multilayer liquid film forming step. Therefore, in this step, drying of the multilayer liquid film is started before the layers of the multilayer liquid film are separated.

  As explained in the curing agent addition step, the addition of the curing agent not only promotes gelation and imidization, but also accumulates residual components in the gap between the support and the multilayer gel film, so that the multilayer gel film The peelability of the is improved. This out-of-system discharge of the remaining components is one of the important operational effects by adding a curing agent.

  However, when the residual component is accumulated between the layers constituting the multilayer gel film (individual gel film) instead of the gap between the multilayer gel film and the support, the adhesion between the layers decreases, Delamination occurs between layers and the multilayer structure is destroyed. That is, when a multilayer liquid film is formed using a polyimide varnish to which a curing agent is added and dried to obtain a multilayer gel film, there arises a problem that the layers are easily peeled off. Accordingly, the out-of-system discharge of the remaining components is also an undesirable phenomenon in the production of the multilayer film.

  Therefore, in the present invention, in order to achieve both the peelability of the multilayer gel film from the support and the prevention of delamination between the layers of the multilayer gel film, the temperature of the multilayer liquid film is increased as quickly as possible. Residual components (organic solvent, reaction solution such as water produced by gelation reaction, dehydrating agent, etc.) are evaporated. This can suppress or avoid the accumulation of the remaining components between the layers of the multilayer structure, so that the resulting multilayer gel film has improved interlayer adhesion, resulting in excellent multilayer structure in the resulting multilayer film. Can be. In other words, in the present invention, since the drying is started before the interlayer of the multilayer liquid film is peeled off, it is possible to avoid a situation where the gelation reaction proceeds before the evaporation of the residual component is started. Can do.

  In this step, in order to dry the multilayer liquid film as quickly as possible, the time for starting the drying, that is, the time for starting the drying process before the layers of the multilayer liquid film are peeled off is the polyimide varnish used and the curing. Varies depending on the type of agent, the cooling temperature in the varnish cooling process, the temperature of the surrounding environment, the configuration of the device for forming the multilayer liquid film (liquid film formation conditions), and is not particularly limited Absent. Whether or not delamination occurs in the multilayer liquid film can be determined by lightly rubbing the upper surface of the portion near the end of the multilayer liquid film with a finger or the like. When a gap occurs between the layers due to rubbing with a finger or the like, the curing reaction (gelation) proceeds in the multilayered liquid film, and the above remaining components accumulate between the layers to form a low-viscosity liquid film layer. It has been shown. Therefore, the drying process may be started before such interlayer misalignment occurs.

  More specifically, it is preferable to start the drying process within 2 minutes, starting from the time when the multilayer liquid film is formed on the support (when the multilayer liquid film forming step is completed), and within 30 seconds. It is more preferable to start the drying process, and it is even more preferable to start within 10 seconds.

  The drying method in this step is not particularly limited as long as it is a method capable of proceeding with gelation, but a method capable of effectively evaporating the remaining components at the initial stage is more preferable. Specifically, a drying method by heating can be suitably used. The specific heating method is not particularly limited, and a conventionally known heating method can be suitably used. The heating temperature is preferably 60 ° C. or higher and 200 ° C. or lower, and 80 ° C. or higher and 150 ° C. or lower. It is more preferable that

  By setting the heating temperature at the time of gelation (drying temperature of the multilayer liquid film) within the range of 60 to 200 ° C., not only can the gelation of the liquid film proceed efficiently, but also the remaining components in the initial stage of drying. Can be effectively evaporated. As a result, delamination between layers can be more effectively suppressed. On the other hand, if the temperature is below the above temperature range, the remaining components may not be effectively evaporated. Moreover, when it exceeds the said temperature range, it will become easy to adhere a multilayer gel film on a support body, and it exists in the tendency for the peelability of a multilayer gel film to fall.

  Further, the drying time is not particularly limited, but is preferably within a range of 1 to 60 minutes regardless of the heating method. When the heating time is within the above range, the multilayer gel film can be produced efficiently and reliably. On the other hand, when the drying time is out of the above range, it may be hardly dried or excessively dried.

<Baking process>
The firing step is a step of firing the multilayer gel film obtained in the gel film forming step to complete imidization. Thereby, the polyimide-type multilayer film by which the some polyimide layer was laminated | stacked can be obtained.

  The heating method used in the baking step is not particularly limited as long as it is a method capable of effectively heating the multilayer gel film to be fired into the multilayer film. Specifically, for example, the upper surface of the film or A system in which hot air of 100 ° C. or higher is sprayed and heated from the lower surface or both surfaces, or a system in which far infrared rays are irradiated onto the film can be suitably used.

  The firing temperature in the firing step is not particularly limited as long as imidization can be completed and the remaining components can be sufficiently evaporated, but is preferably 200 ° C. or more and 600 ° C. or less, It is preferable to gradually increase the temperature. If the firing temperature is too high, unevenness of temperature is likely to occur in the firing of the multilayer film and flatness tends to be lost. If it is too low, sufficient firing treatment may not be performed. The firing time is not particularly limited, and the firing can be performed within a conventionally known range as long as imidization can be completed.

  In addition, the manufacturing method concerning this invention does not need to include all the said varnish preparation process, a hardening | curing agent addition process, a varnish cooling process, a multilayer liquid film formation process, a gel film formation process, and a baking process, as mentioned above. In addition, when forming the multilayer liquid film, if at least the addition of the curing agent and the drying process before delamination between layers are performed in combination, each step may be appropriately omitted or other steps may be added. can do.

<Preferred example of multilayer film formation>
The method for producing a multilayer film according to the present invention can be widely used for the production of a polyimide-based multilayer film in which a plurality of polyimide layers are laminated, and the specific type of the multilayer film is not particularly limited. As a representative example, a polyimide-based adhesive film can be given.

  The polyimide-based adhesive film includes at least a structure in which a heat-resistant polyimide layer and a thermoplastic polyimide layer are directly laminated. The heat-resistant polyimide layer is made of a resin composition containing a heat-resistant polyimide, and is a polyimide layer that functions as an insulating layer (insulating film). Moreover, the said thermoplastic polyimide layer consists of a resin composition containing a thermoplastic polyimide, and is a polyimide layer which functions as an adhesive layer (adhesive film). Such an adhesive film can be suitably used as a substrate material such as a two-layer FPC.

  The more specific configuration of the polyimide-based adhesive film is not particularly limited, and a thermoplastic polyimide layer may be laminated on both sides of the heat-resistant polyimide layer, or only one side may be laminated. In addition, polyimide layers other than these may be included, and a plurality of laminated structures of a heat-resistant polyimide layer and a thermoplastic polyimide layer may be included. Further, the plurality of polyimide layers include a heat-resistant polyimide layer and a thermoplastic polyimide layer directly laminated thereon, and the thermoplastic polyimide layer may be positioned on at least one surface layer. .

  Thus, the present invention can be applied to the production of a multilayer film in which any kind of polyimide layer is combined. For example, when the polyimide-based multilayer film obtained in the present invention is used as a raw material for a two-layer FPC, a structure in which a thermoplastic polyimide layer is in close contact with one side or both sides of a heat-resistant polyimide layer may be used. In this case, it is formed from a polyimide varnish (thermoplastic polyimide varnish) to be a thermoplastic polyimide layer on at least one surface of a liquid film formed from a polyimide varnish (heat resistant polyimide varnish) to be a heat resistant polyimide layer. A production method in which a liquid film having a multilayer structure in contact with the liquid film is formed on a support, and this is heated and dried to obtain a gel film and then fired at a high temperature can be mentioned as a particularly preferable embodiment.

  In particular, from the practical aspect of FPC, the specific configuration of the adhesive film is most preferably a three-layer structure in which a thermoplastic polyimide layer is in close contact with both surfaces of a heat-resistant polyimide layer. Therefore, when manufacturing such a three-layered adhesive film (multilayer film), a liquid film formed from a thermoplastic polyimide varnish is formed on both sides of a liquid film formed from a heat-resistant polyimide varnish. A most preferred embodiment is a production method in which a liquid film having a three-layer structure in contact is formed on a support, and this is heated and dried, followed by high-temperature firing.

  Here, the curing agent (dehydrating agent and catalyst) may be added to any polyimide varnish that forms any polyimide layer, but the curing agent need not necessarily be added to all polyimide varnishes. For example, when manufacturing the said adhesive film for two-layer FPC, it is preferable to add a hardening | curing agent only to a heat resistant polyimide-type varnish.

  Thermoplastic polyimide varnish generally has a low molecular weight, a high gelation reaction rate, and a fine microstructure. Therefore, when a curing agent is added to the thermoplastic polyimide varnish, only the polyimide varnish forms a gel film having a dense structure first, so that the central liquid film (becomes a heat-resistant polyimide layer) in the multilayer liquid film. A gel film having a dense structure is formed on the outer layer of the liquid film. As a result, the residual component discharged from the heat-resistant polyimide varnish loses the escape field and is accumulated between the layers, so that the delamination phenomenon between the layers is more likely to occur.

  In contrast, when a curing agent is added only to the heat-resistant polyimide varnish, the remaining components are discharged to the outside of the liquid film as the gelation reaction of the heat-resistant polyimide varnish proceeds. Among these remaining components, the curing agent (dehydrating agent and catalyst) penetrates into the adjacent liquid film, that is, the inside of the thermoplastic polyimide varnish, and gradually promotes the gelation reaction of the thermoplastic polyimide varnish. . As a result, the adhesion between the gel film generated from the heat-resistant polyimide varnish and the gel film generated from the thermoplastic polyimide varnish and the interlayer is improved, so that delamination between layers can be more effectively suppressed or avoided. .

(II) Synthesis of Polyamic Acid The multilayer film according to the present invention is preferably constituted by laminating at least two kinds of polyimide-based films. And as above-mentioned, it is preferable that one film is a heat resistant polyimide layer. Thereby, the polyimide-type multilayer film concerning this invention will have heat resistance at least. The other film is preferably a thermoplastic polyimide layer as described above. Thereby, as for the polyimide-type multilayer film concerning this invention, a thermoplastic polyimide layer will play the role of an adhesive agent under high temperature. Such a multilayer film makes it easy to attach an insulating film (heat-resistant polyimide layer) to a metal foil such as a copper foil by a thermocompression bonding method. Therefore, a high-performance polyimide film for a printed circuit board is produced. It becomes possible to do.

<Heat resistant polyimide layer>
Here, if the heat-resistant polyimide layer is made of a resin composition containing 90% by weight or more of non-thermoplastic polyimide, its specific composition, polyimide molecular structure used, layer thickness, etc. It is not limited. As described above, the non-thermoplastic polyimide used for the heat-resistant polyimide layer is produced using polyamic acid as a precursor.

  Any known method can be used as a method for producing this polyamic acid (synthesis method, polymerization method), and is not particularly limited. Usually, an acid dianhydride component composed of one or more acid dianhydrides and a diamine component composed of one or more diamines are dispersed or dissolved in a synthesis solvent so as to be substantially equimolar amounts. A method of stirring until the polymerization of each monomer component is completed under controlled temperature conditions can be suitably used. In addition, aromatic tetracarboxylic dianhydride etc. are used suitably as an acid dianhydride component, and aromatic diamine etc. are used suitably as a diamine component.

  The obtained polyamic acid is in a state of being dispersed or dissolved in a synthesis solvent, that is, in an organic solvent solution (polyamic acid solution), and the solid content concentration is usually within a range of 5 to 35% by weight, preferably 10 to 30% by weight. %. If the solid content concentration is within this range, a polyamic acid having an appropriate molecular weight is synthesized, and the polyamic acid solution also has a preferable solution viscosity for work.

  In addition, you may add an inorganic or organic filler to the said heat resistant polyimide layer and the polyimide-type varnish for forming this as needed.

<Polyamide acid polymerization method>
As the polymerization method of the polyamic acid, any conventionally known method and a combination thereof can be used. A characteristic of the polyamic acid polymerization method is the order of addition of the monomer components. Therefore, various physical properties of the obtained polyimide can be controlled by controlling the order of addition of the monomer components. Therefore, in the present invention, any monomer component addition method may be used for the polymerization of the polyamic acid. Examples of typical polymerization methods include the following methods. These methods may be used singly or in combination. In the present invention, polyamic acid obtained using any of the following polymerization methods may be used.
(1) An aromatic diamine is dissolved in an organic polar solvent, and substantially equimolar aromatic tetracarboxylic dianhydride is added and reacted with this to polymerize.
(2) An aromatic tetracarboxylic dianhydride is reacted with a small molar amount of an aromatic diamine in an organic polar solvent to obtain a prepolymer having acid anhydride groups at both ends. Subsequently, the aromatic diamine is further added and polymerized so that the aromatic tetracarboxylic dianhydride and the aromatic diamine are substantially equimolar in all steps.
(3) An aromatic tetracarboxylic dianhydride is reacted with an excess molar amount of an aromatic diamine in an organic polar solvent to obtain a prepolymer having amino groups at both ends. Subsequently, after adding aromatic diamine here, aromatic tetracarboxylic dianhydride is added so that aromatic tetracarboxylic dianhydride and aromatic diamine compound are substantially equimolar in all steps. Add and polymerize.
(4) After the aromatic tetracarboxylic dianhydride is dissolved and / or dispersed in an organic polar solvent, an aromatic diamine compound is added and polymerized so as to be substantially equimolar.

  In particular, in the present invention, in order to obtain a heat-resistant polyimide, a polymerization method for obtaining a prepolymer using a diamine having a rigid structure to be described later (referred to as a rigid diamine for convenience) may be used. By using this polymerization method, a polyimide film having a high elastic modulus and a small hygroscopic expansion coefficient tends to be easily obtained.

  In the above polymerization method, the molar ratio of the rigid diamine and the acid dianhydride used when preparing the prepolymer is preferably in the range of 100: 70 to 100: 99 or 70: 100 to 99: 100, and more preferably 100: 75 to More preferably within the range of 100: 90 or 75: 100 to 90: 100. If the molar ratio is below the above range, it is difficult to obtain an effect of improving the elastic modulus and the hygroscopic expansion coefficient. If the molar ratio is above the above range, the linear expansion coefficient becomes too small, or the tensile elongation is deteriorated. Sometimes.

<Acid dianhydride component used in the production of non-thermoplastic polyimide>
In the present invention, in producing the non-thermoplastic polyimide contained in the heat-resistant polyimide layer, the acid dianhydride component used for the synthesis of the polyamic acid as a precursor is not particularly limited, For example, pyromellitic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 1,2, 5,6-naphthalenetetracarboxylic dianhydride, 2,2 ′, 3,3′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 4, 4′-oxyphthalic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, bis (3,4- Dicarboxyl Enyl) propane dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,1-bis (3,4-dicarboxyphenyl) ethane dianhydride, bis (2,3 -Dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) ethane dianhydride, oxydiphthalic dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, p-phenylenebis (Trimellitic acid monoester acid anhydride), ethylene bis (trimellitic acid monoester acid anhydride), bisphenol A bis (trimellitic acid monoester acid anhydride), or the like. These compounds may be used singly or in combination of two or more at any ratio.

  Among the acid dianhydrides, pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 4,4′-oxyphthalic dianhydride, 3,3 ′, 4 At least one compound selected from the group of 4,4′-biphenyltetracarboxylic dianhydride can be particularly preferably used.

  The amount used when the above four particularly preferred acid dianhydrides are used is preferably 60 mol% or less, more preferably 55 mol% or less, and more preferably 50 mol based on the total acid dianhydride. More preferably, it is% or less. When using at least one of the above four particularly preferred tetracarboxylic dianhydrides, if the amount used exceeds the above range, the glass transition temperature (Tg) of the resulting heat-resistant polyimide layer becomes too low, or polyamide Since the storage modulus of the acid solution when heated is too low, film formation itself may be difficult.

  The amount of pyromellitic dianhydride used as the tetracarboxylic dianhydride is preferably in the range of 40 to 100 mol%, more preferably in the range of 45 to 100 mol%, and 50 to 100 mol. % Is more preferable. If pyromellitic dianhydride is used within this range, the Tg of the resulting heat-resistant polyimide layer and the storage modulus of the polyamic acid solution when heated can be easily maintained within a range suitable for use or film formation.

<Diamine component used for production of non-thermoplastic polyimide>
In the present invention, in producing the non-thermoplastic polyimide contained in the heat-resistant polyimide layer is not particularly limited as a diamine component used for the synthesis of the polyamic acid as a precursor, specifically, For example, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenylmethane, benzidine, 3,3'-dichlorobenzidine, 3,3'-dimethylbenzidine, 2,2'-dimethylbenzidine, 3,3'- Dimethoxybenzidine, 2,2′-dimethoxybenzidine, 4,4′-diaminodiphenylsulfide, 3,3′-diaminodiphenylsulfone, 4,4′-diaminodiphenylsulfone, 4,4′-oxydianiline, 3,3 '-Oxydianiline, 3,4'-oxydianiline, 1,5-diaminonaphthalene, 4,4'-diamino Phenyldiethylsilane, 4,4′-diaminodiphenylsilane, 4,4′-diaminodiphenylethylphosphine oxide, 4,4′-diaminodiphenyl N-methylamine, 4,4′-diaminodiphenyl N-phenylamine, 1, 4-diaminobenzene (p-phenylenediamine), 1,3-diaminobenzene, 1,2-diaminobenzene, bis {4- (4-aminophenoxy) phenyl} sulfone, bis {4- (4-aminophenoxy) phenyl } Propane, bis {4- (3-aminophenoxy) phenyl} sulfone, 4,4′-bis (4-aminophenoxy) biphenyl, 4,4′-bis (3-aminophenoxy) biphenyl, 1,3-bis (3-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,3 Bis (4-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 3,3'-benzophenone, 4,4'-diamino benzophenone, or it can be given these analogs and the like. These compounds may be used singly or in combination of two or more at any ratio.

  As the diamine component, a rigid diamine having a rigid structure and a diamine having a flexible structure can be used in combination. The preferable use ratio in that case should just be in the range of 80 / 20-20 / 80 by molar ratio, It is more preferable to exist in the range of 70 / 30-30 / 70, 60 / 40-30 / 70 More preferably, it is in the range. When the use ratio of rigid diamine exceeds the above range, the tensile elongation of the resulting heat-resistant polyimide layer tends to be small. Moreover, if the ratio of the rigid diamine used is below the above range, the Tg of the resulting heat-resistant polyimide layer becomes too low, or the storage elastic modulus of the polyamic acid solution when heated becomes too low, making film formation difficult. It may be accompanied by harmful effects such as

  The rigid diamine in the present invention is a group selected from the group consisting of divalent aromatic groups represented by the following general formula (1).

In addition, R < ² > in General formula (1) is represented by General formula group (2).

R ³ in the general formula group (2) is the same or different and is H—, CH ₃ —, —OH, —CF ₃ , —SO ₄ , —COOH, —CO—NH ₂ , Cl—, Br—, F -, and CH ₃ is any one group selected from the group consisting of O-.

  On the other hand, the diamine having a flexible structure has a flexible structure such as an ether group, a sulfone group, a ketone group, and a sulfide group, and is preferably represented by the following general formula (3).

Incidentally, R ⁴ in the general formula (3) in the general formula group (4)

In which R ⁵ is the same or different and is H—, CH ₃ —, —OH, —CF ₃ , —SO ₄ , —COOH, or a group selected from the group consisting of divalent organic groups , —CO—NH ₂ , Cl—, Br—, F—, and CH ₃ O—.

  In the present invention, the polyimide varnish for forming the heat-resistant polyimide layer is the above acid dianhydride component so that the finally obtained heat-resistant polyimide layer (polyimide film) is a film having desired characteristics. In addition, the type and mixing ratio of the diamine component can be appropriately determined and used.

  Here, as the preferred polymerization solvent for synthesizing the polyamic acid, any solvent can be used as long as it dissolves the polyamic acid, but an amide solvent, that is, N, N-dimethylformamide, N, N- Examples thereof include dimethylacetamide and N-methyl-2-pyrrolidone, and N, N-dimethylformamide, N, N-dimethylacetamide and the like can be particularly preferably used. These polymerization solvents can be used as they are as solvents for polyimide varnish.

<Thermoplastic polyimide layer>
The thermoplastic polyimide layer concerning this invention should just be formed from the resin composition containing a thermoplastic polyimide. Here, the thermoplastic polyimide used (in a broad sense) includes thermoplastic polyimide (in a narrow sense), thermoplastic polyamideimide, thermoplastic polyetherimide, thermoplastic polyesterimide, and the like, but is not particularly limited. . These resins may be used alone or in combination of two or more. Among the above resins, thermoplastic polyesterimide can be particularly preferably used because of its low hygroscopicity.

  When the thermoplastic polyimide layer is laminated on the heat-resistant polyimide layer as an adhesive layer to become an adhesive film, it is sufficient that it can exhibit a significant adhesive force especially when laminating laminates by the laminating method. The conditions such as the content of the thermoplastic polyimide (broadly defined), the molecular structure, and the thickness of the thermoplastic polyimide layer are not particularly limited. However, it is preferable that substantially 50% by weight or more of thermoplastic polyimide (in a broad sense) is contained in order to develop a significant adhesive force.

  In addition, an inorganic or organic filler may be added to the thermoplastic polyimide layer and the polyimide varnish for forming the thermoplastic polyimide layer, if necessary.

  The said thermoplastic polyimide (broad sense) can also be obtained by the conversion reaction from the polyamic acid which is the precursor similarly to the said non-thermoplastic polyimide. As the method for producing the polyamic acid, any known synthesis method can be used as in the case of the non-thermoplastic polyimide precursor.

  Moreover, it is preferable that the thermoplastic polyimide (broad sense) used for this invention has the Tg in the range of 150-300 degreeC. In addition, Tg can be calculated | required from the value of the inflexion point of the storage elastic modulus measured with the dynamic viscoelasticity measuring apparatus (DMA). When Tg is within the above range, lamination can be performed with an existing apparatus, and the heat resistance of the obtained adhesive film (multilayer film) is not impaired.

  The polyamic acid that is a precursor of the thermoplastic polyimide (in a broad sense) used in the present invention is not particularly limited, and any conventionally known polyamic acid can be used. Regarding the production of this polyamic acid solution, the monomer raw materials and production conditions described for the non-thermoplastic polyimide can be used in exactly the same manner.

  The thermoplastic polyimide (in a broad sense) can be adjusted in various characteristics by combining various monomer raw materials to be used. In general, when the use ratio of the rigid diamine increases, the Tg increases or the polyamic acid increases. In some cases, the storage elastic modulus of the solution when heated increases, resulting in poor adhesion and workability. The use ratio of the rigid diamine is preferably 40 mol% or less, more preferably 30 mol% or less, and particularly preferably 20 mol% or less.

  A preferred specific example of the thermoplastic polyimide (in a broad sense) is imidization of polyamic acid obtained by polymerizing an acid dianhydride component containing biphenyltetracarboxylic dianhydrides and a diamine component having an aminophenoxy group. However, it is not particularly limited.

  As described above, in the present invention, a chemical dehydrating agent and a catalyst (curing agent) are added to at least two kinds of varnishes, preferably cooled polyimide-based compounds, so that the varnish is formed as a liquid film having a multilayer structure. A gel film is obtained by performing a drying process faster than peeling between layers of the obtained liquid film having a multilayer structure, and this is subjected to a heat baking process at a high temperature. Thereby, in the film-forming of the polyimide-type compound of a multilayer structure, while improving productivity, delamination can be prevented and a polyimide-type multilayer film with high interlayer adhesiveness can be manufactured.

(III) Polyimide-based multilayer film manufacturing apparatus The polyimide-based multilayer film manufacturing apparatus according to the present invention is not particularly limited as long as it is an apparatus for performing the multilayer film manufacturing method having the above-described configuration. The specific configuration of the manufacturing apparatus can be selected as appropriate according to the scale of manufacture, purpose, and the like. For example, in Examples 1 to 3 described later, in Examples 1 to 3, since a polyimide-based multilayer film is manufactured at a small laboratory level, a syringe or an aluminum foil is used. Utilizes industrial production level manufacturing equipment.

  Specifically, as an industrial production level manufacturing apparatus, for example, as shown in FIG. 1, a film forming unit 10, varnish tanks 11, 12 a, 12 b, a curing agent tank 13, a liquid mixer 14, The structure provided with the endless belt 16, the continuous drying furnace 17, the continuous baking furnace 18, and the multilayer film winding part 19 can be mentioned. This manufacturing apparatus is an apparatus for manufacturing the above-described adhesive film, that is, a multilayer film having a structure in which a thermoplastic polyimide layer is formed on both surfaces of a heat-resistant polyimide layer.

<Configuration to supply polyimide varnish>
The varnish tanks 11, 12 a, and 12 b are solution supply means for supplying a polyimide varnish, and thus, in the manufacturing apparatus according to the present invention, a solution supply means for enabling a plurality of types of polyimide varnish to be supplied. Are provided. Among these, in the case of at least one solution supply means, that is, the example shown in FIG. 1, a polyimide varnish containing a dehydrating agent and a catalyst (curing agent) in advance can be supplied from the varnish tank 11.

  Of the three varnish tanks, the varnish tank 11 is a central layer tank 11 for storing a polyimide varnish for forming a heat-resistant polyimide layer, and the varnish tanks 12a and 12b are thermoplastic. It is an upper layer tank 12a and a lower layer tank 12b for storing a polyimide varnish for forming a polyimide layer. These tanks for varnish are all connected to the film forming unit 10 via a pipe 15. In particular, the liquid tank 14 is interposed in the middle of the pipe 15 in the tank 11 for the central layer. Since the liquid mixer 14 is connected to the hardener tank 13 by the pipe 15, the hardener tank 13 and the central layer tank 11 are joined together by the liquid mixer 14 via the pipe 15. Thus, the film forming unit 10 is connected.

  The specific configuration of the varnish tanks 11, 12 a, and 12 b is not particularly limited, and a conventionally known tank can be suitably used. The same applies to the pipe 15, and conventionally known pipes can be suitably used. The size, material, and the like of these tanks and pipes are appropriately set depending on the production scale, the type of multilayer film to be produced, detailed production conditions, and the like, and are not particularly limited. The configuration other than the tank and piping is basically the same.

  Each of the varnish tanks 11, 12 a, 12 b and the curing agent tank 13 can cool the internal polyimide varnish or the curing agent solution. The specific structure of the cooling unit provided in these tanks is not particularly limited, and the polyimide varnish or the curing agent solution is at room temperature or lower, preferably 10 ° C. or lower, as described above. As described above, since the lower limit may be cooled to −10 ° C. or higher, a conventionally known cooling device capable of such cooling may be used.

  In the varnish tanks 11, 12 a, and 12 b and the curing agent tank 13, the polyimide varnish and the curing agent solution are cooled before forming the multilayer liquid film, so that the polyimide varnish is produced in the production apparatus according to the present invention. The progress of gelation can be controlled. As a specific cooling temperature, the polyimide varnish or the curing agent solution only needs to be within the above temperature range. Therefore, the cooling temperature may be appropriately set according to the configuration of the cooling unit, the configuration of the tank, and the like. Usually, the temperature for cooling the tank needs to be lower than the set temperature of the polyimide varnish in consideration of the thermal conductivity, and is preferably −20 ° C. or higher and 10 ° C. or lower, and −15 More preferably, the temperature is from 5 ° C to 5 ° C, and particularly preferably from -10 ° C to 0 ° C.

  Since the curing agent tank 13 and the liquid mixer 14 are for adding a curing agent solution (dehydrating agent and catalyst) to the polyimide varnish for the central layer, they can be called curing agent supply means. The specific configuration of the curing agent supply means is not limited to the combination of the curing agent tank 13 and the liquid mixer 14, but it is efficient to make the curing agent into a solution and mix it. The structure of the said combination which mixes a hardening | curing agent solution with a polyimide-type varnish via 15 is more preferable.

  The specific configuration of the curing agent tank 13 is not particularly limited, and a conventionally known tank can be suitably used in the same manner as the varnish tank. Further, the specific configuration of the liquid mixer 14 is not particularly limited, but when the viscosity of the polyimide varnish and the curing agent solution is compared, the polyimide varnish is higher and the curing agent is lower. Therefore, an apparatus that can efficiently mix a low-viscosity liquid with a high-viscosity liquid can be suitably used. Specifically, for example, a stirring tank equipped with a stirring blade in a container with a fixed volume, a structure in which a rotor having a large number of pins arranged inside a double cylindrical tube is rotated, a static mixer, and a large number of disks are moved up and down in a cylinder. The structure etc. which are made to exercise can be mentioned.

  Moreover, it is preferable that the liquid mixer 14 can also be cooled from the reason for controlling the gelation of the polyimide varnish. Since the temperature for cooling the liquid mixer 14 needs to be lower than the set temperature of the polyimide varnish, similarly to the cooling temperature of the tank, it is preferably -20 ° C. or higher and 10 ° C. or lower, for example.

<Configuration for forming a multilayer liquid film>
In the varnish tanks 11, 12 a, 12 b, the curing agent tank 13, and the liquid mixer 14, the curing agent addition step and the varnish cooling step in the production method according to the present invention are performed. A liquid film forming step is performed. The manufacturing apparatus shown in FIG. 1 includes a film forming unit 10 as means for forming a multilayer liquid film.

  The specific configuration of the film forming unit 10 is not particularly limited, as long as a multilayer liquid film formed by laminating a plurality of liquid films made of the polyimide varnish can be formed on the support. However, specifically, a discharge means for discharging the polyimide varnish supplied from the varnish tanks 11, 12 a, and 12 b to the support, for example, a conventionally known die can be suitably used. Specific examples of such dies include multilayer coextrusion dies, slide dies, and single layer dies. In the case of a single-layer die, a plurality of single-layer dies are arranged in parallel and a single-layer liquid film is sequentially applied.

  As the multilayer coextrusion die, for example, as shown in FIG. 2, a three-layer coextrusion die having a configuration in which one central layer flow path 22a and two outer layer flow paths 22b are formed inside the die body 21. Can be mentioned. The varnish tank 11 (and the curing agent tank 13 and the liquid mixer 14), which is a central layer tank, is connected to the central layer flow path 22a, and a polyimide varnish for the central layer (for example, heat resistant) Volatile polyimide varnish) is in circulation. Further, the varnish tank 12a, which is an upper layer tank, is connected to the left side in the figure of the outer layer flow path 22a, and an upper layer polyimide varnish (for example, a thermoplastic polyimide varnish) is provided. It comes to circulate. Similarly, the varnish tank 12b, which is a lower layer tank, is connected to the right side in the drawing of the outer layer flow path 22a, and a lower layer polyimide varnish (for example, a thermoplastic polyimide varnish). Has come to circulate.

  In the three-layer coextrusion die, the three flow paths merge in the die body 21 and are connected to one discharge port 23. Accordingly, the polyimide varnishes supplied from the varnish tanks 11, 12 a, and 12 b merge in the die body 21 and are discharged from the discharge port 23 as a three-layer liquid film. As a result, the multilayer liquid film 50 having a three-layer structure in which the outer layers (upper layer 52 and lower layer 53) are laminated on both surfaces of the central layer 51 can be directly formed on the support (endless belt 16).

  Next, as the slide die, for example, as shown in FIG. 3, an upper layer flow path 32b, a center layer flow path 32a, and a lower layer flow path 32c are arranged in this order in the die body 31. The thing of a structure can be mentioned. In this configuration, the upper layer discharge port 33b corresponding to the upper layer flow channel 32b, the center layer discharge port 33a corresponding to the center layer flow channel 32a, and the lower layer discharge port 33c corresponding to the lower layer flow channel 32c are arranged in this order. The portions of the die body 31 provided with the discharge ports are inclined surfaces 34 inclined downward from the upper layer discharge ports 33b toward the lower layer discharge ports 33c. Further, a lip portion 35 protruding outward from the die body 31 is formed at a position on the outer side when viewed from the lower layer discharge port 33c so that the liquid film can be satisfactorily cast on the support (endless belt 16). Has been.

  In the slide die, similarly to the three-layer coextrusion die, the varnish tank 12a and the varnish tank 11 are respectively provided for the upper layer flow path 32b, the central layer flow path 32a, and the lower layer flow path 32c. , And a tank 12b for varnish are connected. Therefore, the polyimide varnish supplied from these tanks is discharged from each discharge port. Here, the lower layer polyimide varnish discharged from the lower layer discharge port 33 c below the inclined surface 34 flows out directly onto the inclined surface 34 and flows down from the lip portion 35 onto the lower support.

  A central layer discharge port 33a is formed above the inclined surface 34 when viewed from the lower layer discharge port 33c. Therefore, the central layer polyimide varnish discharged from the central layer discharge port 33a is laminated on the lower surface polyimide varnish continuously discharged from the lower layer discharge port 33c. It flows out and flows down from the lip portion 35 onto the lower support.

  Further, an upper layer discharge port 33b is formed above the inclined surface 34 when viewed from the center layer discharge port 33a. Therefore, the upper-layer polyimide varnish discharged from the upper-layer discharge port 33b is stacked on the central-layer polyimide varnish continuously discharged from the center-layer discharge port 33a. Since the central layer polyimide varnish is laminated on the lower polyimide varnish as described above, it flows out on the inclined surface 34 in a state where a liquid film having a three-layer structure of the upper layer, the central layer and the lower layer is formed. , It flows down from the lip 35 onto the lower support. As a result, a multilayer liquid film 50 having a three-layer structure in which the outer layers (upper layer 52 and lower layer 53) are laminated on both surfaces of the central layer 51 is formed on the support (endless belt 16).

  Next, as a single layer die (single layer extrusion die), as shown in FIG. 4, corresponding to the upper layer, the center layer, and the lower layer polyimide varnish, each having a structure in which single layer dies are arranged in parallel. Can do. In this configuration, an upper layer single layer die 41b, a central layer single layer die 41a, and a lower layer single layer die 41c are arranged in this order from the downstream side in the traveling direction of the endless belt (support) 16 (arrows in the figure). ing. Each single-layer die has the same configuration, and a polyimide varnish flow path 42b, 42a or 42c is formed inside the main body, and a discharge port 43b, 43a or 43c is formed at the tip of the die. ing.

  Since the lower layer single layer die 41c is provided on the most upstream side when viewed from the traveling direction, the lower layer polyimide varnish discharged from the die is cast on the endless belt 16 to form a liquid film (lower layer). 53). Since the central layer single layer die 41a is provided immediately downstream of this, the central layer polyimide varnish discharged from this die is cast on the lower layer 53 to form a liquid film (central layer 51). Form. In this state, a liquid film having a two-layer structure of the central layer 51 and the lower layer 53 is formed on the support.

  Further, since the upper layer single layer die 41b is provided on the most downstream side, the upper layer polyimide varnish discharged from this die is cast on the central layer 51 and the liquid film (upper layer 52) is formed. Form. As a result, a multilayer liquid film 50 having a three-layer structure in which the upper layer 52, the central layer 51, and the lower layer 53 are stacked in this order from the top is formed.

  In addition to the above structures, a liquid film having a multilayer structure can be formed on the support by using a method such as spraying, knife-edge coating, or gravure coating.

  In particular, in the present invention, the film forming unit 10 preferably has a configuration that allows a plurality of types of polyimide-based varnishes to be simultaneously discharged onto a support, and more preferably a coextrusion die. The method of forming a plurality of liquid films at the same time (coextrusion method) has a higher adhesiveness to each other than the method of sequentially laminating liquid films (sequential method), and in particular, a coextrusion die was used. It is preferable to use the coextrusion casting film forming method because the adhesion between the liquid films can be further improved. There are two types of the coextrusion die, a multi-manifold type and a feed block type, and it is more preferable to use a multi-manifold type co-extrusion die. By this. The uniformity of the thickness of each layer to be formed can be further increased.

  In addition, from the reason for controlling the gelation of the polyimide varnish, it is preferable that the film forming unit 10, that is, the above various dies can be cooled. Since the temperature for cooling the die needs to be lower than the set temperature of the polyimide varnish similarly to the cooling temperature of the tank, it is preferably -20 ° C. or higher and 10 ° C. or lower, for example.

<Support>
In the film forming section 10, the support on which the multilayer liquid film 50 is to be formed is not particularly limited, and the multilayer liquid film 50 is formed in a state where the discharged polyimide varnish is cast. As long as the surface (formation surface) has smoothness, it is sufficient. The specific structure of the said support body is not specifically limited, For example, a metal belt, a metal roller, a resin belt, a resin film, a resin roller etc. can be mentioned.

  Among these, it is preferable that the said support body is a rotary body from the point of manufacturing efficiency. If it is a rotary body, a liquid film can be formed continuously by rotating the same support, and the next gel film forming step (drying and gelation of the liquid film) can be carried out. Specific examples of the support as the rotating body include a belt-like support that is rotatably stretched by a plurality of rotating shafts, and a drum (roller) -like support that is rotatable by a single rotating shaft. be able to. For example, in FIGS. 1 to 4, an endless belt 16 stretched by two shaft rollers is used as a support.

  The material of the support is not particularly limited as long as it does not affect the formation of the liquid film, but the present invention includes a process of drying the multilayer liquid film at a high temperature. Can be suitably used. Further, it is preferable that the surface of the metal support is sufficiently polished. By such polishing, the gel film produced after drying can be easily peeled off from the support. Furthermore, in order to enhance the peelability of the gel film, it is more preferable to subject the surface of the metal support to surface treatment such as plating, Teflon (registered trademark) coating, or Teflon (registered trademark) -containing plating.

  Further, among the curing agents used in the present invention, in particular, dehydrating agents are generally highly corrosive, and therefore, metals such as stainless steel and hastelloy steel are preferably used as the support material. By using such a metal material, it can endure both a dehydrating agent and high-temperature heating. Furthermore, the support used in the present invention is preferably heatable. As described above, after the multilayer liquid film is formed, it is required to heat and dry the liquid film as quickly as possible. By such rapid heating and drying, it is possible to effectively suppress or avoid the accumulation of residual components discharged with the progress of the gelation reaction between the layers of each liquid film (gel film). The adhesion between the layers can be improved.

<Configuration for drying and gelling liquid film>
The multilayer liquid film formed on the support is heated by a heating means and dried to gel (gel film forming step). Thereby, a multilayer gel film having self-supporting property is obtained. Here, in the present invention, in producing the multilayer gel film, preferably, after cooling the polyimide varnish and adding a curing agent to at least one polyimide varnish, a multilayer liquid film is formed, The formed multilayer liquid film is subjected to a drying treatment as quickly as possible, that is, before peeling occurs between the layers of the multilayer liquid film, to obtain a multilayer gel film.

  First, the drying means used for drying the multilayer liquid film is not particularly limited, but generally, drying by heating is efficient, and thus a conventionally known heating / drying apparatus is preferably used. be able to. In particular, in the present invention, the continuous drying furnace 17 that heats the multilayer liquid film 50 in the state where the multilayer liquid film 50 on the endless belt 16 is carried in can be preferably used. Since the endless belt 16 is used as a support and continuous drying is possible, as described above, if the endless belt 16 itself is a heatable support, further rapid heating is possible. -It is preferable because drying is possible.

  In the present embodiment, as shown in FIG. 1, a multilayer liquid film 50 is formed by the film forming unit 10 above one end portion (the right end portion in the drawing) of the endless belt 16. By the rotation, the multilayer liquid film 50 is moved (conveyed) to the lower side of the right end through the other end (left end in the figure). Therefore, the configuration shown in FIG. 1 includes a continuous drying furnace 17 provided as a heating means so as to cover most of the left side of the endless belt 17 in the drawing. With such a continuous drying furnace 17, the multilayer liquid film 50 on the endless belt 16 can be dried from the upper side to the lower side of the right end of the endless belt 16, and the apparatus configuration Can also be made compact.

  The heating temperature in the continuous drying furnace 17 is not particularly limited, but as described in the gel film forming step, the organic solvent contained in the liquid film, the reaction liquid generated by the gelation reaction, A sufficiently high temperature is required to evaporate the dehydrating agent and the like. On the other hand, if the heating temperature is too high, the multilayer gel film is fixed on the support. Therefore, the heating temperature is preferably 60 ° C. or higher and 200 ° C. or lower, and more preferably 80 ° C. or higher and 150 ° C. or lower.

  Here, a specific method for quickly starting heating of the multilayer liquid film before peeling occurs between the layers of the multilayer liquid film is not particularly limited. For example, the configuration shown in FIG. In this manufacturing apparatus, the relationship between the distance from the coextrusion die (film forming unit 10) to the continuous drying furnace 17 and the belt moving speed of the endless belt 16 is a multilayer liquid film formed on the endless belt 16. It is only necessary that 50 be brought into the continuous drying furnace 17 within 2 minutes. In other words, the distance from the film forming unit 10 to the continuous drying furnace 17 and / or the rotational speed of the endless belt 16 so that the multilayer liquid film 50 can be carried into the continuous drying furnace 17 within 2 minutes after formation. Is preferably set.

  Structurally, as shown in FIG. 1, a region W that is a region between the film forming unit 10 and the entrance of the continuous drying furnace 17 (a region from when the multilayer liquid film is formed to when it is dried). In this case, since the multilayer liquid film 50 is not heated, the rotational speed of the endless belt 16 is increased or the distance of the area W is shortened in order to shorten the time required for the multilayer liquid film 50 to move in the area W. You can respond by doing.

  The time during which the multilayer liquid film 50 passes through the region W, that is, the time during which the multilayer liquid film 50 immediately after formation is carried into the continuous drying furnace 17 may be within 2 minutes, but may be within 30 seconds. Preferably, it is within 10 seconds. The specific rotation speed of the endless belt 16 and the specific distance of the region W are not particularly limited because they are appropriately changed depending on the more specific configuration of the manufacturing apparatus.

  In addition, since the start of drying may be within 2 minutes after the formation of the multilayer liquid film 50, if the configuration of the support and the drying device is different from the configuration shown in FIG. What is necessary is just to set a structure and to control operation | movement of an apparatus.

<Configuration for firing gel film>
As shown in FIG. 1, in the continuous drying furnace 17, the multilayer liquid film 50 becomes the multilayer gel film 54 by the above-described drying treatment. Accordingly, the multilayer gel film 54 is discharged from the continuous drying furnace 17 and the multilayer gel film 54 is discharged. The film 54 is peeled off from the endless belt 16 and baked. The baking means used here is not particularly limited as long as it is baked to imidize the gel film, but the multilayer gel film 54 in the state where the multilayer gel film 54 on the support is carried in. The continuous firing furnace 18 for firing 54 is preferable.

  After peeling off the multilayer gel film 54, the remaining components remaining in the multilayer gel film 54 (an organic solvent, a reaction solution generated by a gelling reaction, a dehydrating agent, a catalyst, etc.) are heated and baked to a higher temperature. In addition to complete evaporation, in particular, when the liquid film is formed of a polyimide-based varnish containing polyamic acid, imidation of the polyamic acid, which is only partially made by gelation, is terminated. Thereby, a polyimide-type multilayer film can be manufactured.

  The specific configuration of the continuous firing furnace 18 is not particularly limited as long as it is a heating furnace capable of effectively heating the multilayer gel film 54 to be fired into the polyimide multilayer film 55. Specifically, For example, a hot-air furnace of a system in which hot air is sprayed on the entire film to heat or a far-infrared furnace equipped with a far-infrared generator for irradiating the film with far-infrared rays can be suitably used.

  The heating temperature (firing temperature) in the continuous firing furnace 18 is not particularly limited, and the type of the multilayer gel film 54, that is, the polyimide-based multilayer film 55 to be obtained, the type of dehydrating agent and catalyst used, and imidization. It can set suitably according to these conditions. In general, the temperature is preferably 200 ° C. or more and 600 ° C. or less as described in the section of the baking step. Moreover, it is preferable to use the method of raising temperature gradually at the time of baking.

  Therefore, as the continuous firing furnace 18, it is more preferable to use a staged heating furnace connecting a plurality of heating furnaces. As each heating furnace used at this time, only a hot air furnace or only a far infrared furnace may be used, or a hot air furnace and a far infrared furnace may be mixed. Moreover, it is preferable that a heat insulating means for partitioning each heating furnace is provided between the heating furnaces so as not to transmit heat from the heating furnace at the preceding stage in the traveling direction to the heating furnace at the next stage. The heat insulating means is not particularly limited, and a known configuration can be used.

  Further, when the multilayer gel film 54 is heated and fired in the continuous firing furnace 18, the method for transporting the multilayer gel film 54 in the continuous firing furnace 18 is not particularly limited, and transported in a conventionally known configuration. do it. For example, the structure which conveys the inside of the continuous baking furnace 18 in the state which fixed the both ends of the multilayer gel film 54 with the clip or the needle | hook can be mentioned.

<Other configurations>
The manufacturing apparatus shown in FIG. 1 includes a multilayer film winding unit 19 for winding a polyimide multilayer film 55 that has been baked in a continuous baking furnace 18 and completely imidized. The specific configuration is not particularly limited, and a conventionally known configuration can be appropriately employed.

  Thus, in the manufacturing apparatus, as shown in FIG. 1, the film forming section 10, the tanks for varnish 11, 12a, 12b, the tank for curing agent 13, the liquid mixer 14, the endless belt 16, the continuous drying furnace 17, the continuous firing furnace 18, the multilayer film take-up unit 19 and the like can be mentioned. Of course, the manufacturing apparatus according to the present invention is not limited to this, and other configurations are appropriately selected. It may be provided, or a part of the configuration may not be provided as necessary.

  As described above, in the production apparatus according to the present invention, a solution of a plurality of types of polyimide compounds (polyimide varnish) is introduced from a reservoir into a mixer, and a chemical dehydrating agent and a catalyst (curing agent) are added in the mixer. The mixed liquid thus obtained is introduced into an apparatus (film forming section) for producing a liquid film having a multilayer structure on a substrate (support). And after heating and drying the multilayer liquid film on the substrate to obtain a gel film having a multilayer structure having self-holding properties, the gel film is peeled off from the substrate, and the gel film is heat-treated at a high temperature to obtain a multilayer. A polyimide compound film (multilayer film) having a structure can be obtained. Thereby, in the film-forming of the polyimide-type compound of a multilayer structure, while improving productivity, delamination can be prevented and a polyimide-type multilayer film with high interlayer adhesiveness can be manufactured.

  The present invention will be described more specifically based on examples and comparative examples, but the present invention is not limited to this. Those skilled in the art can make various changes, modifications, and alterations without departing from the scope of the present invention. In addition, the peeling between layers in the multilayer liquid film and the multilayer gel film in the following Examples and Comparative Examples, and the peelability of the multilayer gel film from the support were evaluated as follows.

[Delamination between multilayer liquid film and multilayer gel film]
For the multilayer liquid film, after a predetermined time has elapsed since the multilayer liquid film was formed on the support, for the multilayer gel film, the support on which the multilayer liquid film was formed was dried under predetermined conditions. After being obtained, the peeling between layers was evaluated by visually observing and confirming the presence or absence of peeling.

[Peelability of multilayer gel film from support]
The peelability from the support was evaluated by grasping and pulling the end of the multilayer gel film.

[Synthesis Example 1; Synthesis of polyamic acid as precursor of heat-resistant polyimide]
76.2 kg of DMF was cooled to 10 ° C., 3.7 kg of p-phenylenediamine (PDA) was added thereto, and while stirring under a nitrogen atmosphere, 3,3 ′, 4,4′-biphenyltetra was further added. 9.8 kg of carboxylic acid dianhydride (BPDA) was gradually added and stirred for 30 minutes. 41.4 g of a 10% DMF dispersion of calcium hydrogen phosphate particles was added to the solution, and the mixture was sufficiently stirred to obtain a reaction solution. As the calcium hydrogen phosphate particles, those having a particle size distribution in which the median average diameter is 2 μm and the ratio of the particle diameter of 7 μm or more is 0.05%.

  Next, a solution in which 300 g of BPDA was dissolved in 2 kg of DMF was separately prepared, and this was gradually added to the above reaction solution while paying attention to the viscosity and stirred. When the viscosity reached 3500 poise, the addition was stopped to obtain a polyamic acid solution having a solid concentration of 15% by weight. Since this polyamic acid solution is an organic solvent solution of a precursor of heat resistant polyimide, it is hereinafter referred to as a heat resistant polyimide varnish.

[Synthesis Example 2; Synthesis of polyamic acid used as precursor of thermoplastic polyimide]
78 kg of DMF was cooled to 10 ° C., and 11.56 kg of 2,2-bis [4- (4-aminophenoxy) phenyl] propane (BAPP) was added thereto, and the mixture was further stirred under a nitrogen atmosphere. Was gradually added. Subsequently, 380 g of ethylenebis (trimellitic acid monoester anhydride) (TMEG) was added and stirred for 30 minutes to obtain a reaction solution.

  Next, a solution in which 300 g of TMEG was dissolved in 3 kg of DMF was separately prepared, and this was gradually added to the above reaction solution while paying attention to the viscosity and stirred. When the viscosity reached 3000 poise, the addition was stopped, and 43.7 kg of DMF was further added to obtain a polyamic acid solution having a solid content concentration of 14% by weight. Since this polyamic acid solution is an organic solvent solution of a precursor of thermoplastic polyimide, it is hereinafter referred to as a thermoplastic polyimide varnish.

[Example 1]
In this example, a three-layer coextrusion die having the structure shown in FIG. 2 was used as a discharge means (film forming section) for forming a multilayer liquid film.

  First, 6.5 g of acetic anhydride (dehydrating agent) and 3.9 g of isoquinoline (catalyst) were dissolved in 19.6 g of DMF to prepare 30 g of a curing agent. This curing agent was added to and mixed with 100 g of heat-resistant polyimide varnish cooled to 10 ° C. The obtained mixed solution was defoamed with a centrifugal separator and then filled into a syringe, and this syringe was connected to the flow path of the central layer of the three-layer coextrusion die. At the same time, a syringe filled with only the thermoplastic polyimide varnish cooled to 10 ° C. was connected to the flow path of the outer layer of the three-layer coextrusion die.

  Each syringe was operated, and a heat-resistant polyimide varnish (containing a curing agent) was injected into the three-layer coextrusion die at a rate of 1.0 kg / hr and a thermoplastic polyimide varnish at a rate of 0.17 kg / hr. As a result, a multilayer liquid film having a three-layer structure is extruded from the lip of the three-layer coextrusion die and cast on an aluminum foil (support) that moves at a speed of 1.0 m / min. A liquid film was formed on the aluminum foil.

  After the multilayer liquid film was formed on the aluminum foil, 30 seconds passed, and the multilayer liquid film was visually observed, but no peeling was observed. Then, the multilayer liquid film was put into a drying furnace together with the aluminum foil, and dried at 130 ° C. for 100 seconds to obtain a multilayer gel film. The obtained multilayer gel film was visually observed, but peeling was not observed. Thereafter, the multilayer gel film was peeled off from the aluminum foil. The peelability was good.

  The multilayer gel film thus peeled off was fixed with a pin frame and baked at temperatures of 300 ° C. × 30 seconds, 400 ° C. × 50 seconds, 450 ° C. × 10 seconds to complete imidization. Thereby, a polyimide multilayer film having a three-layer structure in which a thermoplastic polyimide layer (adhesive layer) was laminated on both surfaces of a heat-resistant polyimide layer (insulating layer) was obtained. The adhesion between the layers in this multilayer film was good.

[Example 2]
After the heat-resistant polyimide-based varnish and the thermoplastic polyimide-based varnish have been cooled to 0 ° C. and after the multilayer liquid film has been formed on the aluminum foil for 1 minute, the multilayer liquid film is dried together with the aluminum foil in a drying furnace. A polyimide-based multilayer film having a three-layer structure in which a thermoplastic polyimide layer (adhesive layer) was laminated on both surfaces of a heat-resistant polyimide layer (insulating layer) was obtained in the same manner as in Example 1 except that it was put in

  In this example, no peeling was observed in either the multilayer liquid film or the multilayer gel film, and the peelability of the multilayer gel film was good. Furthermore, the adhesiveness between the layers of the obtained multilayer film was also good.

Example 3
A thermoplastic polyimide layer (adhesive layer) is laminated on both sides of a heat resistant polyimide layer (insulating layer) in the same manner as in Example 1 except that the heat resistant polyimide varnish and the thermoplastic polyimide varnish are cooled to 0 ° C. A three-layer polyimide multilayer film was obtained.

  In this example, no peeling was observed in either the multilayer liquid film or the multilayer gel film, and the peelability of the multilayer gel film was good. Furthermore, the adhesiveness between the layers of the obtained multilayer film was also good.

Example 4
After the heat-resistant polyimide-based varnish and the thermoplastic polyimide-based varnish were cooled to 0 ° C. and after the multilayer liquid film was formed on the aluminum foil, 1 minute and 30 seconds passed, and then the multilayer liquid film was combined with the aluminum foil. A polyimide multilayer film having a three-layer structure in which a thermoplastic polyimide layer (adhesive layer) is laminated on both sides of a heat-resistant polyimide layer (insulating layer) is obtained in the same manner as in Example 1 except that it is put in a drying furnace. It was.

  In this example, no peeling was observed in either the multilayer liquid film or the multilayer gel film, and the peelability of the multilayer gel film was good. Furthermore, the adhesiveness between the layers of the obtained multilayer film was also good.

Example 5
After the heat-resistant polyimide-based varnish and the thermoplastic polyimide-based varnish have been cooled to 0 ° C. and after the multilayer liquid film has been formed on the aluminum foil for 2 minutes, the multilayer liquid film is dried together with the aluminum foil in a drying furnace. A polyimide-based multilayer film having a three-layer structure in which a thermoplastic polyimide layer (adhesive layer) was laminated on both surfaces of a heat-resistant polyimide layer (insulating layer) was obtained in the same manner as in Example 1 except that it was put in

  In this example, no peeling was observed in either the multilayer liquid film or the multilayer gel film, and the peelability of the multilayer gel film was good. Furthermore, the adhesiveness between the layers of the obtained multilayer film was also good.

Example 6
After the heat-resistant polyimide-based varnish and the thermoplastic polyimide-based varnish are cooled to −10 ° C. and after the multilayer liquid film is formed on the aluminum foil, the multilayer liquid film is dried together with the aluminum foil. A polyimide-based multilayer film having a three-layer structure in which a thermoplastic polyimide layer (adhesive layer) was laminated on both sides of a heat-resistant polyimide layer (insulating layer) was obtained in the same manner as in Example 1 except that it was put in a furnace. .

  In this example, no peeling was observed in either the multilayer liquid film or the multilayer gel film, and the peelability of the multilayer gel film was good. Furthermore, the adhesiveness between the layers of the obtained multilayer film was also good.

Example 7
After the heat-resistant polyimide varnish and the thermoplastic polyimide varnish have been cooled to -10 ° C and after the multilayer liquid film has been formed on the aluminum foil for 30 seconds, the multilayer liquid film is dried together with the aluminum foil. A polyimide-based multilayer film having a three-layer structure in which a thermoplastic polyimide layer (adhesive layer) was laminated on both sides of a heat-resistant polyimide layer (insulating layer) was obtained in the same manner as in Example 1 except that it was put in a furnace. .

  In this example, no peeling was observed in either the multilayer liquid film or the multilayer gel film, and the peelability of the multilayer gel film was good. Furthermore, the adhesiveness between the layers of the obtained multilayer film was also good.

[Comparative Example 1]
After the heat-resistant polyimide-based varnish and the thermoplastic polyimide-based varnish have been cooled to −10 ° C. and after the multilayer liquid film has been formed on the aluminum foil for 3 minutes, the multilayer liquid film is dried together with the aluminum foil. A multilayer liquid film having a three-layer structure was obtained in the same manner as in Example 1 except that it was put in a furnace. In this multilayer liquid film, at the end, between the lower layer (thermoplastic polyimide varnish liquid film) and the intermediate layer (heat resistant polyimide varnish liquid film) and the intermediate layer (heat resistant polyimide varnish liquid film) A slight gap between layers was observed between the (liquid film) and the upper layer (thermoplastic polyimide varnish liquid film).

  Thereafter, this multilayer liquid film was placed in a drying furnace together with an aluminum foil, and dried at 130 ° C. for 100 seconds in the same manner as in Example 1 to obtain a multilayer gel film. In the obtained multilayer gel film, the gel film in the intermediate layer and the upper layer contracted, and peeling occurred between the gel film in the lower layer and subsequent baking treatment became impossible.

[Comparative Example 2]
After the heat-resistant polyimide-based varnish and the thermoplastic polyimide-based varnish have been cooled to 0 ° C. and after the multilayer liquid film has been formed on the aluminum foil for 3 minutes, the multilayer liquid film is dried together with the aluminum foil in a drying furnace. A multilayer liquid film having a three-layer structure was obtained in the same manner as in Example 1 except that it was put in In this multilayer liquid film, a gap between layers considered to be slightly peeled between the lower layer and the intermediate layer and between the intermediate layer and the upper layer was observed at the end.

  Thereafter, this multilayer liquid film was placed in a drying furnace together with an aluminum foil, and dried at 130 ° C. for 100 seconds in the same manner as in Example 1 to obtain a multilayer gel film. In the obtained multilayer gel film, the gel film in the intermediate layer and the upper layer contracted, and peeling occurred between the gel film in the lower layer and subsequent baking treatment became impossible.

[Comparative Example 3]
A multilayer liquid film having a three-layer structure is formed on an aluminum foil in the same manner as in Example 1 except that the heat-resistant polyimide varnish and the thermoplastic polyimide varnish are used at room temperature (20 ° C.) without being cooled. Tried. However, the liquid film discharged from the three-layer coextrusion die partially undergoes a curing reaction, and a liquid film that is not smooth and partially uneven is formed on the aluminum foil.

  When the liquid film is observed after 30 seconds have elapsed since the non-smooth liquid film was formed on the aluminum foil, at a plurality of locations of the liquid film, between the lower layer and the intermediate layer, and between the intermediate layer and the upper layer. A gap between layers, which seems to be slightly peeled, was observed between them. Thereafter, this multilayer liquid film was placed in a drying furnace together with an aluminum foil, and dried at 130 ° C. for 100 seconds in the same manner as in Example 1 to obtain a multilayer gel film. In the obtained multilayer gel film, the gel film in the intermediate layer and the upper layer contracted, and peeling occurred between the gel film in the lower layer and subsequent baking treatment became impossible.

Example 8
In the present embodiment, unlike the first to third embodiments, a manufacturing apparatus having the structure shown in FIG. 1 is used, and the discharge means (film forming section) for forming a multilayer liquid film is the same as in the first to third embodiments. A three-layer coextrusion die having the structure shown in FIG. 2 was used. As the three-layer coextrusion die, a multi-manifold type having a lip width of 12 cm was used.

  First, in the manufacturing apparatus shown in FIG. 1, a film forming unit 10, a tank 11 for varnish for storing a heat-resistant polyimide varnish, tanks 12a and 12b for varnish for storing a thermoplastic polyimide varnish, and a curing agent for storing a curing agent. The temperature of the tank 13 and the liquid mixer 14 was adjusted in advance to 0 ° C.

  Next, the varnish tank 11 was filled with a heat-resistant polyimide varnish, and the heat-resistant polyimide varnish was introduced from the inlet of the liquid mixer 14 through the pipe 15 at a rate of 0.77 kg / hr. In addition, a hardener solution was prepared by dissolving 1 kg of DMF (solvent), 0.33 kg of acetic anhydride (dehydrating agent), and 0.20 kg of isoquinoline (catalyst) in advance. Filled. And the said hardening | curing agent solution was introduce | transduced from the other entrance of the liquid mixer 14 through the piping 15 at the speed | rate of 0.23 kg / hr.

  Since the liquid mixer 14 supplies a mixture of a heat-resistant polyimide varnish and a curing agent solution, the mixture (a heat-resistant polyimide varnish containing a curing agent) is fed at a rate of 1 kg / hr. While injecting into the central layer flow path 22a (see FIG. 2) of the layer coextrusion die, the outer layer flow path 22b (FIG. 2) of the thermoplastic polyimide varnish at a rate of 0.17 kg / hr. 2).

  A multilayer liquid film 50 having a three-layer structure extruded from the lip of the three-layer coextrusion die was cast on a stainless steel endless belt 16 rotating at a speed of 1.0 m / min. The entrance of the continuous drying furnace 17 is installed at a position at a distance of 0.5 m from the position where the multilayer liquid film 50 having the three-layer structure is cast on the endless belt 16, and the formed multilayer liquid film 50 is continuously formed. It introduce | transduced in the type | formula drying furnace 17, and it heated by continuous operation on the conditions of 130 degreeC x 100 second.

  The time from when the multilayer liquid film 50 was formed on the endless belt 16 to the continuous drying furnace 17, that is, the time for the multilayer liquid film 50 to pass through the region W was 30 seconds. That is, the multilayer liquid film 50 is dried after passing through the region W over 30 seconds after the formation. At this time, no delamination was observed in the multilayer liquid film 50.

  When the multilayer gel film 54 was peeled off from the endless belt 16 and observed after the drying process was finished, no delamination was observed in the multilayer gel film 54. Thereafter, the multilayer gel film 54 was fixed to a tenter clip, and the multilayer gel film was dried and imidized. The continuous firing furnace 18 used here is a combination of a continuous hot-air drying furnace and an infrared drying furnace, and conditions corresponding to 300 ° C. × 30 seconds, 400 ° C. × 50 seconds, 450 ° C. × 10 seconds. Baked in.

  Thereby, a polyimide multilayer film having a three-layer structure in which a thermoplastic polyimide layer (adhesive layer) was laminated on both surfaces of a heat-resistant polyimide layer (insulating layer) was obtained. The adhesion between the layers in this multilayer film was good.

[Comparative Example 2]
A manufacturing apparatus having the same configuration as in Example 4 was used. First, in the manufacturing apparatus, a film forming unit 10, a varnish tank 11 for storing a heat-resistant polyimide varnish, varnish tanks 12a and 12b for storing a thermoplastic polyimide varnish, and a curing agent tank 13 for storing a curing agent. The temperature of the liquid mixer 14 was adjusted to 8 ° C. in advance.

  Next, the varnish tank 11 was filled with a heat-resistant polyimide varnish, and the heat-resistant polyimide varnish was introduced from the inlet of the liquid mixer 14 through the pipe 15 at a rate of 0.25 kg / hr. In addition, a hardener solution was prepared by dissolving 1 kg of DMF (solvent), 0.33 kg of acetic anhydride (dehydrating agent), and 0.20 kg of isoquinoline (catalyst) in advance. Filled. And the said hardening | curing agent solution was introduce | transduced from the other entrance of the liquid mixer 14 through the piping 15 at the speed | rate of 0.083 kg / hr.

  Since the liquid mixer 14 supplies a mixture of a heat-resistant polyimide varnish and a curing agent solution, the mixture (a heat-resistant polyimide varnish containing a curing agent) is fed at a rate of 0.17 kg / hr. The three-layer coextrusion die is injected into the central layer flow path 22a (see FIG. 2), and the thermoplastic polyimide varnish is injected at a rate of 0.03 kg / hr, and the three-layer coextrusion die outer layer flow path 22b. (See FIG. 2).

  A multilayer liquid film 50 having a three-layer structure extruded from the lip of the three-layer coextrusion die was cast on a stainless steel endless belt 16 rotating at a speed of 0.17 m / min. The entrance of the continuous drying furnace 17 is installed at a position at a distance of 0.5 m from the position where the multilayer liquid film 50 having the three-layer structure is cast on the endless belt 16, and the formed multilayer liquid film 50 is continuously formed. It introduce | transduced in the type | formula drying furnace 17, and it heated by continuous operation on the conditions of 120 degreeC x 100 second.

  The time from when the multilayer liquid film 50 was formed on the endless belt 16 to the continuous drying furnace 17, that is, the time for the multilayer liquid film 50 to pass through the region W was 3 minutes. That is, the multilayer liquid film 50 is dried after passing through the region W over 3 minutes after the formation. At this time, the end portion of the multilayer liquid film 50 includes an upper layer 52 (a layer in contact with air) and the central layer 51, and a central layer 51 and a lower layer 53 (a layer in contact with the endless belt 16). In the meantime, peeling due to slight deviation was observed.

  After the drying process was finished, the multilayer gel film 54 was peeled off from the endless belt 16 and observed, and in most parts of the gel film, it was observed that the lowermost layer gel and the intermediate layer gel were separated, It was found that the three-layer structure was destroyed.

  Note that the present invention is not limited to the configurations described above, and various modifications are possible within the scope of the claims, and technical means disclosed in different embodiments and examples respectively. Embodiments and examples obtained by appropriately combining them are also included in the technical scope of the present invention.

  As described above, in the present invention, when producing a multilayer film having a plurality of polyimide layers made of a resin composition containing polyimide, a multilayer liquid containing a liquid film by adding a chemical dehydrating agent and a catalyst (curing agent). While forming the film, the drying process is started before peeling of each liquid film occurs. Therefore, it is possible to sufficiently exhibit the effect of adding the curing agent without damaging the multilayer structure. Therefore, the present invention can be used not only in the field of manufacturing polyimide films, but also in the manufacture of various electronic components such as FPC, TAB, high-density recording media using the film, and fields of use thereof. It can be applied to a wide range of fields.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1, showing an embodiment of the present invention, is a schematic diagram showing the configuration of a production apparatus that performs a method for producing a multilayer film according to the present invention. FIG. 2 is a partial cross-sectional view illustrating an embodiment of the present invention and illustrating an example of a configuration of a three-layer coextrusion die that can be used in a film forming unit of the manufacturing apparatus illustrated in FIG. 1. FIG. 5 is a partial cross-sectional view showing another embodiment of the present invention and showing an example of the configuration of a slide die that can be used as the film forming section. FIG. 24 is a partial cross-sectional view illustrating still another embodiment of the present invention and illustrating an example of a configuration in which single-layer dies that can be used as the film forming unit are combined.

Explanation of symbols

10 Film-forming part (Discharging means)
11 Tank for varnish (solution supply means)
12a Tank for varnish (solution supply means)
12b Tank for varnish (solution supply means)
13 Hardener tank (solution supply means)
14 Solution mixer (solution supply means)
15 Piping 16 Endless belt (support, rotating body, belt-like support)
17 Continuous drying furnace (drying means, heating furnace)
18 Continuous firing furnace (firing means, firing furnace)
21 Die body (coextrusion die, discharge means)
31 Die body (slide die, discharge means)
41a Single layer die for center layer 41b Single layer die for upper layer 41c Single layer die for lower layer 50 Multilayer liquid film 54 Gel film 55 Polyimide multilayer film

Claims (19)

A method for producing a polyimide-based multilayer film having a plurality of polyimide layers made of a resin composition containing polyimide,
A multilayer liquid film forming step of forming a multilayer liquid film by laminating a plurality of organic solvent solutions containing polyimide or a precursor thereof on a support, and by drying and gelling the multilayer liquid film, A gel film forming step for obtaining a self-supporting multilayer gel film,
Furthermore, a dehydrating agent and a catalyst are added in advance to at least one of the organic solvent solutions used in the multilayer liquid film forming step,
In the said gel film formation process, before the interlayer of the said multilayer liquid film peels, drying of the said multilayer liquid film is started, The manufacturing method of the polyimide-type multilayer film characterized by the above-mentioned.   2. The multilayer liquid film forming step according to claim 1, wherein the multilayer liquid film is formed by a coextrusion casting film forming method in which a plurality of types of organic solvent solutions are simultaneously extruded and cast on a support. A method for producing a polyimide-based multilayer film.   3. The method for producing a polyimide-based multilayer film according to claim 1, wherein, in the gel film forming step, drying is started within 2 minutes from the time when the multilayer liquid film is formed on the support.   4. The method for producing a polyimide-based multilayer film according to claim 3, wherein, in the gel film forming step, drying is started within 30 seconds from the time when the multilayer liquid film is formed on the support.   In the said gel film formation process, the temperature at the time of drying a multilayer liquid film shall be in the range of 60-200 degreeC, The manufacture of the polyimide type multilayer film of any one of Claim 1 thru | or 4 characterized by the above-mentioned. Method. The plurality of polyimide layers include a heat-resistant polyimide layer made of a resin composition containing a heat-resistant polyimide and a thermoplastic polyimide layer made of a resin composition containing a thermoplastic polyimide,
The multilayer liquid film is formed so that the liquid film to be a thermoplastic polyimide layer is in contact with at least one surface of the liquid film to be a heat resistant polyimide layer in the multilayer liquid film forming step. 6. The method for producing a polyimide-based multilayer film according to any one of 5 above.   The method for producing a polyimide-based multilayer film according to claim 6, wherein a dehydrating agent and a catalyst are added only to the organic solvent solution to be the heat-resistant polyimide layer.   Furthermore, before the said multilayer liquid film formation process, the solution cooling process which cools the said organic solvent solution below normal temperature is included, The polyimide-type multilayer film of any one of Claim 1 thru | or 7 characterized by the above-mentioned. Production method.   In the said solution cooling process, the said organic solvent solution is cooled to 10 degrees C or less, The manufacturing method of the polyimide type multilayer film of Claim 8 characterized by the above-mentioned.   In the said solution cooling process, the minimum of the cooling temperature of the said organic solvent solution shall be -10 degreeC, The manufacturing method of the polyimide-type multilayer film of Claim 8 or 9 characterized by the above-mentioned. An apparatus for producing a polyimide-based multilayer film having a plurality of polyimide layers made of a resin composition containing polyimide,
Solution supply means for supplying an organic solvent solution containing polyimide or a precursor thereof while cooling;
Discharge means for discharging the organic solvent solution supplied from the solution supply means into a liquid film; and
A support for casting a liquid film of an organic solvent solution discharged from the discharge means;
Drying means for gelling the liquid film on the support to form a gel film having self-supporting property;
A baking means for baking to imidize the gel film,
Further, a plurality of the solution supply means are provided so that a plurality of types of organic solvent solutions can be supplied, and at least one solution supply means supplies an organic solvent solution containing a dehydrating agent and a catalyst in advance. Is possible,
The discharge means discharges the organic solvent solution so that a multilayer liquid film formed by laminating a plurality of liquid films can be formed on the support,
The said drying means starts the drying of the said multilayer liquid film, before the interlayer of the said multilayer liquid film peels, The manufacturing apparatus of the polyimide type multilayer film characterized by the above-mentioned.   12. The apparatus for producing a polyimide-based multilayer film according to claim 11, wherein the discharge means is capable of simultaneously discharging liquid films of a plurality of types of organic solvent solutions onto a support.   13. The apparatus for producing a polyimide-based multilayer film according to claim 12, wherein the discharge means is a coextrusion die.   The said support body is a rotary body, The manufacturing apparatus of the polyimide-type multilayer film of Claim 11, 12 or 13 characterized by the above-mentioned.   15. The apparatus for producing a polyimide-based multilayer film according to claim 14, wherein the support is a belt-like support that is rotatably supported by a plurality of rotating shafts.   The polyimide-based multilayer according to any one of claims 11 to 15, wherein the drying means is a heating furnace that heats the multilayer liquid film in a state where the multilayer liquid film on the support is carried in. Film production equipment.   The said support body carries in the heating furnace within 2 minutes after formation of the multilayer liquid film formed by the discharge means, The manufacturing apparatus of the polyimide-type multilayer film of Claim 16 characterized by the above-mentioned.   The distance from the discharge means to the heating furnace and / or the rotation speed of the support is set so that the multilayer liquid film can be carried into the heating furnace within 2 minutes after formation. The manufacturing apparatus of the polyimide-type multilayer film of 17. The polyimide system according to any one of claims 11 to 18, wherein the baking means is a baking furnace for baking the gel film in a state where the gel film peeled off from the support is carried in. Multi-layer film manufacturing equipment.

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