JP4759249B2 - Method for producing polyimide laminate having excellent surface properties - Google Patents

Description

  The present invention relates to a method for coating a solution of thermoplastic polyimide or polyamic acid on a substrate, and a method for producing a polyimide laminate suitably used for flexible printed wiring boards, TAB tapes, particularly two-layer copper-clad laminates, and the like. . More specifically, the present invention relates to a method for producing a polyimide laminate in which a solution obtained by dissolving a thermoplastic polyimide or a polyamic acid layer as a precursor thereof in an organic solvent is applied to at least one surface of a polyimide film.

  In recent years, the demand for various printed circuit boards has increased along with the reduction in weight, size and density of electronic products. In particular, the demand for flexible laminates (also referred to as flexible printed circuit boards (FPCs), etc.) has increased. ing. The flexible laminate has a structure in which a circuit made of a metal foil is formed on an insulating film.

  The flexible laminate is generally formed of various insulating materials, and 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. As the adhesive material, a thermosetting adhesive such as epoxy or acrylic is generally used (FPC using these thermosetting adhesives is hereinafter also referred to as three-layer FPC).

  Thermosetting adhesives have the advantage that they can be bonded at relatively low temperatures. However, in the future, as required characteristics such as heat resistance, flexibility, and electrical reliability become stricter, it is considered that it is difficult to cope with a three-layer FPC using a thermosetting adhesive. On the other hand, an FPC (hereinafter also referred to as a two-layer FPC) in which a metal layer is directly provided on an insulating film or a thermoplastic polyimide is used for an adhesive layer has been proposed. This two-layer FPC has characteristics superior to those of the three-layer FPC, and demand is expected to increase in the future.

  As a method for producing a flexible metal-clad laminate for use in a two-layer FPC, a polyamic acid, which is a polyimide precursor, is cast on a metal foil, applied, and then casted directly onto a polyimide film by sputtering or plating. Examples thereof include a metallizing method for providing a metal layer and a laminating method for bonding a polyimide film and a metal foil through a thermoplastic polyimide. Among these, the lamination 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 apparatus cost is lower than that of the metalizing method. As a device for laminating, a hot roll laminating device or a double belt press device for continuously laminating a roll-shaped material is used. Of these, the hot roll laminating method can be used more preferably from the viewpoint of productivity.

  The polyimide laminate applied to the laminating method has a form in which a thermoplastic polyimide is laminated on a polyimide film as a core. Usually, polyimide or its precursor polyamic acid is dissolved in an organic solvent in the core film. The solution is formed by coating using various coaters such as a die coater, a lip coater, a gravure coater, and a reverse coater.

  However, the polyamic acid that is polyimide or its precursor is limited in the type of solvent that can be dissolved, and the polyimide or polyamic acid itself is originally a high molecular weight product, resulting in poor wettability and problems such as repellency during coating. There was a problem that was likely to occur.

  On the other hand, in Patent Document 1, a solution obtained by dissolving an addition-type polyimide resin in a mixed solvent composed of an aromatic solvent and an oxygen-containing solvent is applied to the surface of a rare earth-based permanent magnet, and the polyimide is obtained by heating and curing the solution. A method for producing a rare earth permanent magnet having a resin film is disclosed, and ether solvents such as dioxolane are also described as oxygen-containing solvents. However, the polyimide used in Patent Document 1 is an addition-type polyimide resin that is cured by heating, and Patent Document 1 aims to improve adhesion with a magnet, and attention is paid to repelling during coating. Not.

Patent Document 2 discloses a soluble polyimide that exhibits a solubility of 10% or more at 20 degrees in any of N, N-dimethylformamide, 1,4-dioxane, 1,3-dioxolane, and tetrahydrofuran. Are listed. However, Patent Document 2 aims at making the polyimide soluble in the solvent by devising the structure of the polyimide, adjusting the solid content concentration by diluting the polyimide solution, and specifying as the dilution solvent There is no mention of using any of the above solvents or repelling during coating.
JP 2001-189205 A WO01 / 034678

  The present invention has been made in view of the above-mentioned problems, and its purpose is to form a coating solution of at least one surface of a base material in which a thermoplastic polyimide or its precursor polyamic acid is dissolved in an organic solvent. It is an object of the present invention to provide a coating method that does not cause surface defects such as repelling and a method for producing a polyimide laminate.

As a result of intensive studies in view of the above problems, the present inventors have found that the above problems can be solved by the following novel laminate production method and coating method.
1) A method for producing a laminate in which a thermoplastic polyimide layer is formed on at least one surface of a substrate, and is obtained by polymerizing at least (A) an aromatic dianhydride component and an aromatic diamine component. Or a step of diluting the solution of the precursor polyamic acid with an organic solvent,
(B) An organic solvent having a saturated vapor pressure at 25 ° C. of 3 kPa to 25 kPa as a dilution solvent used in the step (A) includes a step of applying a diluted thermoplastic polyimide or polyamic acid solution on a substrate. A method for producing a laminate, characterized by being used.
2) The lamination according to 1), wherein the solid content concentration of the solution obtained by diluting the polyamic acid which is the thermoplastic polyimide or its precursor obtained in the step (A) with an organic solvent is 1% to 20%. Body manufacturing method.
3) The method for producing a laminate according to 1) or 2), wherein the substrate is a polyimide film.
4) The total organic solvent of the thermoplastic polyimide or polyamic acid solution used in step (B) contains 5% by weight or more of an organic solvent having a saturated vapor pressure of 3 kPa to 25 kPa at 25 ° C. The manufacturing method of the laminated body as described in any one of 1) -3).
5) The method for producing a polyimide laminate according to any one of 1) to 4), wherein the organic solvent is an ether solvent.
6) A method of applying a solution obtained by dissolving a thermoplastic polyimide or a polyamic acid, which is a precursor thereof, in an organic solvent on at least one surface of a base material, and comprising at least (A) an aromatic acid dianhydride component and an aromatic Diluting a thermoplastic polyimide obtained by polymerizing an aromatic diamine component or a polyamic acid that is a precursor thereof with an organic solvent,
(B) An organic solvent having a saturated vapor pressure at 25 ° C. of 3 kPa to 25 kPa as a dilution solvent used in the step (A) includes a step of applying a diluted thermoplastic polyimide or polyamic acid solution on a substrate. A method for coating a solution of a thermoplastic polyimide or polyamic acid, characterized by being used.

  According to the present invention, when a solution in which a thermoplastic polyimide or a polyamic acid which is a precursor thereof is dissolved in an organic solvent is applied to at least one surface of a base material, the surface property is excellent without causing repelling or the like. .

One embodiment of the present invention will be described below.
The present invention is a method for producing a laminate in which a thermoplastic polyimide layer is formed on at least one surface of a substrate, and is obtained by polymerizing at least (A) an aromatic dianhydride component and an aromatic diamine component. A step of diluting a polyamic acid which is a plastic polyimide or a precursor thereof with an organic solvent,
(B) An organic solvent having a saturated vapor pressure at 25 ° C. of 3 kPa to 25 kPa as a dilution solvent used in the step (A) includes a step of applying a diluted thermoplastic polyimide or polyamic acid solution on a substrate. It is the manufacturing method of the laminated body characterized by using.

(A) Step In step (A), an aromatic acid dianhydride component and an aromatic diamine component are polymerized in an organic solvent to obtain a polyamic acid which is a precursor of a thermoplastic polyimide. Any known method can be used as a method for producing the polyamic acid. Usually, the polyamic acid obtained by dissolving a substantially equimolar amount of an aromatic dianhydride and an aromatic diamine in an organic solvent is obtained. The organic solvent solution is produced by stirring under controlled temperature conditions until the polymerization of the acid dianhydride and the diamine is completed. These polyamic acid solutions are usually obtained at a concentration of 5 to 35 wt%, preferably 10 to 30 wt%. When the concentration is in this range, an appropriate molecular weight and solution viscosity are obtained.

As the polymerization method, any known method and a combination thereof can be used. The characteristic of the polymerization method in the polymerization of polyamic acid is the order of addition of the monomers, and the physical properties of the polyimide obtained can be controlled by controlling the order of addition of the monomers. Therefore, in the present invention, any method of adding monomers may be used for the polymerization of polyamic acid. The following method is mentioned as a typical polymerization method. That is,
1) A method in which an aromatic diamine is dissolved in an organic polar solvent and this is reacted with a substantially equimolar amount of an aromatic tetracarboxylic dianhydride for polymerization.
2) An aromatic tetracarboxylic dianhydride is reacted with a small molar amount of an aromatic diamine compound in an organic polar solvent to obtain a prepolymer having acid anhydride groups at both ends. Then, the method of superposing | polymerizing using an aromatic diamine compound so that an aromatic tetracarboxylic dianhydride and an aromatic diamine compound may become substantially equimolar in all the processes.
3) An aromatic tetracarboxylic dianhydride and an excess molar amount of the aromatic diamine compound are reacted in an organic polar solvent to obtain a prepolymer having amino groups at both ends. Subsequently, after adding an aromatic diamine compound here, using the aromatic tetracarboxylic dianhydride so that the aromatic tetracarboxylic dianhydride and the aromatic diamine compound are substantially equimolar in all steps. How to polymerize.
4) A method in which an aromatic tetracarboxylic dianhydride is dissolved and / or dispersed in an organic polar solvent and then polymerized using an aromatic diamine compound so as to be substantially equimolar.
5) A method of polymerizing by reacting a substantially equimolar mixture of aromatic tetracarboxylic dianhydride and aromatic diamine in an organic polar solvent.
And so on. These methods may be used singly or in combination.

  In the present invention, the polyamic acid obtained by using any of the above polymerization methods may be used, and the polymerization method is not particularly limited.

  Here, the material used for the polyamic acid composition concerning this invention is demonstrated.

  Suitable acid dianhydrides that can be used in the present invention are pyromellitic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic acid. Dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 2,2 ′, 3,3′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-benzophenonetetra Carboxylic dianhydride, 4,4′-oxyphthalic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride , Bis (3,4-dicarboxyphenyl) propane dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,1-bis (3,4-dicarboxyphenyl) Ethane dianhydride, bi (2,3-dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) ethane dianhydride, oxydiphthalic dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, including p-phenylenebis (trimellitic acid monoester acid anhydride), ethylene bis (trimellitic acid monoester acid anhydride), bisphenol A bis (trimellitic acid monoester acid anhydride) and the like, these Can be preferably used alone or in any desired mixture.

  Suitable diamines that can be used in the polyimide precursor polyamic acid solution according to the present invention include 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'-diaminodiphenyldiethylsilane, 4,4'-diaminodiphenylsilane, 4,4'-diaminodiphenylsilane Ruphosphine 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- (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′-diaminobenzophenone, 4,4′-diamino Such as benzophenone and their analogs thereof.

  The polyamic acid solution and the polyimide solution used in the present invention are obtained by appropriately determining the types and blending ratios of the aromatic dianhydride and the aromatic diamine so as to have desired characteristics within the above range. be able to.

  As the preferred solvent for synthesizing the polyamic acid, any solvent can be used as long as it dissolves the polyamic acid. However, amide solvents such as N, N-dimethylformamide, N, N-dimethylacetamide, N- Examples thereof include methyl-2-pyrrolidone, and N, N-dimethylformamide and N, N-dimethylacetamide can be particularly preferably used.

  In addition, a filler can be added for the purpose of improving various film properties such as slidability, thermal conductivity, conductivity, corona resistance, and loop stiffness. Any filler may be used, but preferred examples include silica, titanium oxide, alumina, silicon nitride, boron nitride, calcium hydrogen phosphate, calcium phosphate, mica and the like.

The particle size of the filler is not particularly limited because it is determined by the film characteristics to be modified and the kind of filler to be added, but generally the average particle size is 0.05 to 100 μm, preferably 0.1. It is -75 micrometers, More preferably, it is 0.1-50 micrometers, Most preferably, it is 0.1-25 micrometers. If the particle size is below this range, the modification effect is less likely to appear. If the particle size is above this range, the surface properties may be greatly impaired or the mechanical properties may be greatly deteriorated. Further, the number of added parts of the filler is not particularly limited because it is determined by the film properties to be modified, the filler particle diameter, and the like. Generally, the addition amount of the filler is 0.01 to 100 parts by weight, preferably 0.01 to 90 parts by weight, and more preferably 0.02 to 80 parts by weight with respect to 100 parts by weight of the polyimide. If the amount of filler added is less than this range, the effect of modification by the filler hardly appears, and if it exceeds this range, the mechanical properties of the film may be greatly impaired. Addition of filler
1. 1. A method of adding to a polymerization reaction solution before or during polymerization 2. A method of kneading fillers using three rolls after the completion of polymerization. Any method such as preparing a dispersion containing filler and mixing it with a polyamic acid organic solvent solution may be used, but a method of mixing a dispersion containing filler with a polyamic acid solution, particularly immediately before film formation. This method is preferable because the contamination by the filler in the production line is minimized. When preparing a dispersion containing a filler, it is preferable to use the same solvent as the polymerization solvent for the polyamic acid. Further, in order to disperse the filler satisfactorily and stabilize the dispersion state, a dispersant, a thickener and the like can be used within a range that does not affect the physical properties.

  In the step (A), a polyimide solution can also be used. Many common polyimides are insoluble in a solvent, but a solvent-soluble polyimide can be obtained by adjusting the molecular structure by securing a free volume by a fluorine group, a silicon group, a large substituent, a flexible structure, or the like. The method for producing the polyimide solution is described below.

  The polyamic acid polymer obtained above is dehydrated and closed by a thermal or chemical method to obtain a polyimide. As the imidization method, either a thermal method in which a polyamic acid solution is heat-treated and dehydrated, or a chemical method in which a dehydrating agent is used for dehydration can be used.

  Examples of the dehydrating agent by the chemical method include aliphatic acid anhydrides such as acetic anhydride, and aromatic acid anhydrides. Examples of the catalyst include aliphatic tertiary amines such as triethylamine, aromatic tertiary amines such as dimethylaniline, and heterocyclic tertiary amines such as pyridine and isoquinoline.

  The polyimide obtained as described above can be used as a solution as it is. Alternatively, the solvent used in the polymerization of the polyamic acid dissolves well, but the polyimide solution is poured into a poor solvent in which the polyimide is difficult to dissolve, and the polyimide resin is precipitated and the unreacted monomer is removed and purified, dried and solid The polyimide resin can be appropriately dissolved in a solvent and used as a solution. Examples of the poor solvent used include acetone, methanol, ethanol, isopropanol, benzene, methyl cellosolve, and methyl ethyl ketone.

  Examples of the thermal method include a method in which after polyamic acid is polymerized, it is put into a vacuum oven, imidized by heating under reduced pressure, and taken out as a solid polyimide resin. The obtained solid polyimide resin may be dissolved in an organic solvent to obtain a solution.

  The thermoplastic polyimide in the present invention has a glass transition temperature and is 10 to 400 ° C. (temperature increase rate: 10) in thermomechanical analysis (TMA) in compression mode (probe diameter 3 mmφ, load 5 g). That which causes permanent compression deformation in the temperature range of ° C / min).

  When the laminate produced according to the present invention is used by laminating the thermoplastic polyimide layer and the metal layer of the laminate by a laminating method, the glass transition temperature (Tg) of the adhesive layer from the viewpoint of heat resistance. Is preferably higher, and it is preferable to use an adhesive layer that can be bonded to the metal foil at 300 ° C. or higher. The state “possible to be bonded to a metal foil” as used herein refers to a state in which the storage elastic modulus of the adhesive layer is greatly lowered by heat and expresses meltability. Specifically, the storage elastic modulus of the adhesive layer at 300 ° C. or higher is preferably 10 GPa or less, and more preferably 1 GPa or less. Especially preferably, it is 0.1 GPa or less.

  However, if the Tg of the adhesive layer is excessively increased, the laminating temperature becomes very high, so that it may be impossible to perform lamination with an existing apparatus. The thermoplastic polyimide in the present invention has a Tg in the range of 150 to 300 ° C., considering that it can be laminated with existing equipment and does not impair the heat resistance of the resulting metal-clad laminate. It is preferable. 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).

  In the step (A), the solid content concentration is adjusted by diluting with an organic solvent having a saturated vapor pressure at 25 ° C. of 3 kPa to 25 kPa.

  By the way, the solvent for dissolving the thermoplastic polyimide or its precursor polyamic acid is usually an amide solvent, that is, N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, or the like. Yes, N, N-dimethylformamide and N, N-dimethylacetamide are used. When applying a solution of thermoplastic polyimide or polyamic acid dissolved in these solvents onto the substrate, there are differences depending on the method, but when applying to the substrate by any method, the surface such as repellency Sexual problems may occur. It can be improved within the range that can be adjusted by those skilled in the art, depending on the surface properties of the base material, the viscosity of the coating liquid, the solid content concentration, the molecular weight of the thermoplastic polyimide or polyamic acid, the temperature during drying, and the air volume. Was difficult. The occurrence of repelling is considered to be mainly caused by the wettability of the coating liquid to the polyimide film and the convection of the coating liquid in the drying stage. The improvement of wettability to the polyimide film and the prevention of convection of the coating liquid can be realized by using the specific solvent of the present invention. That is, in the present invention, the solution is used in an organic solvent having a saturated vapor pressure at 25 ° C. of 3 kPa to 25 kPa. Since these solvents volatilize at an early stage after being applied to the base material, dilution with the solvent can reduce the solid content concentration suitable for applying to the base material and fix the coated surface shape. The surface property of the finally obtained thermoplastic polyimide layer can be made excellent. The reason why the saturated vapor pressure at 25 ° C. is defined in the present invention is that the coating environment is usually normal temperature, and the state immediately after coating is a point for surface properties. As a result of examining the solution diluted with various solvents having different saturated vapor pressures at 25 ° C. and adjusting the solid content concentration, the present inventors have diluted a solution diluted with an organic solvent in a range of 3 kPa to 25 kPa. It was found that the surface property of the finally obtained thermoplastic polyimide layer would be excellent if it was coated on a substrate using the above. The solid content concentration of the solution obtained in the step (A) is preferably 1 to 20%. If the saturated vapor pressure is higher than this range, the surface of the coating film is not stabilized and the appearance becomes poor. On the other hand, if the saturated vapor pressure is lower than the above range, solidification of the solution proceeds to cause a problem that gel foreign matter or the like is generated.

Examples of the organic solvent having a saturated vapor pressure at 25 ° C. of 3 kPa to 25 kPa include methyl ethyl ketone and methyl isobutyl ketone, and ether solvents such as tetrahydrofuran, dioxane and dioxolane are particularly preferably used. In the present invention, the saturated vapor pressure at 25 ° C. should be 3 kPa to 25 kPa as a solvent used for dilution, and is 5% by weight or more of the total organic solvent in the diluted solution, preferably 10% by weight or more, More preferably, it is 30% by weight or more. If the amount is less than this range, the effect of improving surface properties becomes small. Maximum amount is not, but arbitrary preferable be used in combination with an amide solvent.

(B) Process (B) A process is a process of apply | coating the diluted thermoplastic polyimide or polyamic acid solution on a base material. Any substrate may be used as the substrate on which the solution is applied. For example, a thermoplastic polyimide or polyamic acid solution is applied on the substrate, and is formed into a film under drying and heating conditions as described below. It may be peeled from the substrate and used as a single layer film, or may be used as it is as a laminate. As the base material, it is preferable to use a polyimide film because occurrence of repelling and the like is less. Hereinafter, the laminated body which used the polyimide film as a base material is demonstrated.

  As a method for obtaining the polyimide laminate according to the present invention, there is a method in which a polyimide film is prepared in advance and a polyamic acid solution, which is a precursor of thermoplastic polyimide, is applied thereon, followed by heat imidization to form a thermoplastic polyimide layer. Can be mentioned. The method of applying the solution includes dipping a polyimide film into the solution. Or the method of apply | coating the solution of a thermoplastic polyimide after producing a polyimide film may be illustrated suitably.

  Among these, when a polyamide acid which is a precursor of thermoplastic polyimide is applied to a polyimide film which is a core and then heated and imidized to obtain a thermoplastic polyimide layer, the method of casting and applying the polyamide acid solution to the core film is applied. Is not particularly limited, and existing methods such as a die coater, a reverse coater, a blade coater and the like can be used.

  A similar method can be used when a thermoplastic polyimide solution is used.

  Thermal imidization method that imidizes only with heat as a method of imidization in a method of forming a polyimide film and applying a polyamic acid solution which is a thermoplastic polyimide precursor on the polyimide film and then imidating by heating to form a thermoplastic polyimide layer And chemical imidization using a dehydrating agent, a catalyst and the like.

  Regardless of which imidation procedure is employed, heating is performed in order to promote imidization efficiently, and the temperature at that time ranges from (glass transition temperature of thermoplastic polyimide−100 ° C.) to (glass transition temperature + 200 ° C.). It is preferable to set within the range of (Glass transition temperature of thermoplastic polyimide−50 ° C.) to (Glass transition temperature + 150 ° C.). The higher the temperature of the heat curing, the easier the imidization occurs, so the curing speed can be increased, which is preferable in terms of productivity. However, if it is too high, the thermoplastic polyimide may cause thermal decomposition. On the other hand, if the temperature of the heat curing is too low, imidization is difficult to proceed even with chemical curing, and the time required for the curing process becomes long.

  As for the imidization time, it suffices to take a sufficient time for the imidization and drying to be substantially completed, and although it is not uniquely limited, generally it is appropriately set within a range of about 1 to 600 seconds. Is done. Moreover, in order to improve the melt fluidity of the adhesive layer, it is possible to intentionally lower the imidization rate and / or leave the solvent.

The tension applied during imidization is preferably in the range of 1 kg / m to 15 kg / m, and particularly preferably in the range of 5 kg / m to 10 kg / m. If the tension is smaller than the above range, sagging or meandering may occur during film conveyance, which may cause problems such as wrinkling during winding or inability to uniformly wind. On the other hand, when it is larger than the above range, since it is heated at a high temperature in a state where a strong tension is applied, the dimensional characteristics of the obtained flexible metal-clad laminate may be deteriorated.
Further, the thermoplastic polyimide layer may contain other materials such as a filler, depending on the application.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited only to these Examples.

  In addition, the evaluation method of the multilayer polyimide laminated body in a synthesis example, an Example, and a comparative example is as follows.

(Appearance evaluation)
Immediately after coating with a die coater, reverse coater and gravure coater, and after drying at 150 ° C. for 2 minutes, the surface was visually inspected to evaluate the number of surface defects (repellency, foam bite).

(Synthesis Example 1)
780 g of DMF and 119 g of 3,3′4,4′-biphenyltetracarboxylic dianhydride (BPDA) were added to a glass flask having a capacity of 2000 ml and stirred for 1 hour under a nitrogen atmosphere, and then in an ice bath. Stir for 30 minutes, add 78.6 g of 3,4'-diaminodiphenyl ether (3,4'-ODA), and prepare a solution in which 2.4 g of 3,4'-ODA is further dissolved in 20 g of DMF. This was gradually added to the reaction solution while stirring the viscosity and stirred. When the viscosity reached 2000 poise, the addition and stirring were stopped to obtain a polyamic acid solution.
This polyamic acid solution was cast on a 25 μm PET film (Therapy HP, manufactured by Toyo Metallizing Co., Ltd.) so as to have a final thickness of 20 μm, and dried at 120 ° C. for 5 minutes. After peeling off the dried self-supporting film from PET, it is fixed to a metal pin frame and dried at 150 ° C. for 5 minutes, 200 ° C. for 5 minutes, 250 ° C. for 5 minutes, 350 ° C. for 5 minutes, A single layer sheet was obtained. The glass transition temperature of this thermoplastic polyimide was 270 ° C. Further, in the determination of thermoplasticity, it was found that the thermoplastic has thermoplasticity due to the occurrence of permanent compression deformation.

(Synthesis Example 2)
780 g of DMF and 115.6 g of 2,2-bis [4- (4-aminophenoxy) phenyl] propane (BAPP) were added to a glass flask having a capacity of 2000 ml, and 3,3′4 while stirring under a nitrogen atmosphere. , 4′-Biphenyltetracarboxylic dianhydride (BPDA) was gradually added. Subsequently, 3.8 g of ethylenebis (trimellitic acid monoester acid anhydride) (TMEG) was added and stirred for 30 minutes in an ice bath. A solution in which 2.0 g of TMEG was dissolved in 20 g of DMF was separately prepared, and this was gradually added to the reaction solution while being careful of the viscosity and stirred. When the viscosity reached 2000 poise, the addition and stirring were stopped to obtain a polyamic acid solution.

  This polyamic acid solution was cast on a 25 μm PET film (Therapy HP, manufactured by Toyo Metallizing Co., Ltd.) so as to have a final thickness of 20 μm, and dried at 120 ° C. for 5 minutes. After peeling off the dried self-supporting film from PET, it is fixed to a metal pin frame and dried at 150 ° C. for 5 minutes, 200 ° C. for 5 minutes, 250 ° C. for 5 minutes, 350 ° C. for 5 minutes, A single layer sheet was obtained. The glass transition temperature of this thermoplastic polyimide was 240 ° C. Further, in the determination of thermoplasticity, it was found that the thermoplastic has thermoplasticity due to the occurrence of permanent compression deformation.

(Synthesis Example 3)
780 g of DMF and 105.5 g of p-phenylenebis (trimellitic acid monoester anhydride) (TMHQ) were added to a glass flask having a capacity of 2000 ml, and the mixture was stirred for 1 hour in a nitrogen atmosphere, and then in an ice bath. Stir for 30 minutes, add 92.6g of BAPP, and further prepare a solution prepared by dissolving 2.1g of BAPP in 20g of DMF, and gradually add this to the above reaction solution while paying attention to the viscosity and stir. It was. When the viscosity reached 2000 poise, the addition and stirring were stopped to obtain a polyamic acid solution.

  This polyamic acid solution was cast on a 25 μm PET film (Therapy HP, manufactured by Toyo Metallizing Co., Ltd.) so as to have a final thickness of 20 μm, and dried at 120 ° C. for 5 minutes. After peeling off the dried self-supporting film from PET, it is fixed to a metal pin frame and dried at 150 ° C. for 5 minutes, 200 ° C. for 5 minutes, 250 ° C. for 5 minutes, 350 ° C. for 5 minutes, A single layer sheet was obtained. The glass transition temperature of this thermoplastic polyimide was 210 ° C. Further, in the determination of thermoplasticity, it was found that the thermoplastic has thermoplasticity due to the occurrence of permanent compression deformation.

(Examples 1-11, Comparative Examples 1-4)
The above polyamic acid solution and polyimide solution are diluted to 6% SC with various solvent compositions and applied to a 17 μm apical HP (manufactured by Kaneka Chemical Co., Ltd.) using a die coater to a dry thickness of 4 μm and dried at 150 ° C. for 2 minutes I let you. The results are shown in Table 1.

比較例１〜比較例２に示すように適切な範囲を外れる有機溶剤を用いると外観・表面性及び欠陥数において劣る結果となった。

As shown in Comparative Examples 1 and 2, when an organic solvent outside the appropriate range was used, the appearance / surface properties and the number of defects were inferior.

  On the other hand, when an organic solvent having a saturated vapor pressure at 25 ° C. in the range of 3 kPa to 25 kPa was used, good results were obtained.

Claims (6)

A method for producing a laminate in which a thermoplastic polyimide layer is formed on at least one side of a base material, the precursor of a thermoplastic polyimide obtained by polymerizing at least (A) an aromatic dianhydride component and an aromatic diamine component A step of diluting the body polyamic acid solution with an ether solvent ,
(B) A step of applying a diluted polyamic acid solution onto a substrate, and using an ether solvent having a saturated vapor pressure at 25 ° C. of 3 kPa to 25 kPa as a dilution solvent used in the step (A). A method for producing a laminate characterized by the above. 2. The laminate according to claim 1, wherein the solid content concentration of the solution obtained by diluting the polyamic acid, which is a precursor of the thermoplastic polyimide obtained in the step (A), with an ether solvent is 1% to 20%. Manufacturing method.   The method for producing a laminate according to claim 1 or 2, wherein the substrate is a polyimide film. (B) All ethereal solvent of the polyamic acid solution used in step, claims, characterized in that the saturated vapor pressure at 25 ° C. are included in a ether solvent is 5 wt% or more 3KPa～25kPa. 1 to The manufacturing method of the laminated body as described in any one of 3. The method for producing a laminate according to any one of claims 1 to 4, wherein the ether solvent is at least one selected from the group consisting of tetrahydrofuran, dioxane, and dioxolane . A method of applying a solution in which a polyamic acid, which is a precursor of a thermoplastic polyimide , is dissolved in an ether solvent on at least one surface of a base material, comprising at least (A) an aromatic acid dianhydride component and an aromatic diamine A step of diluting a polyamic acid, which is a precursor of a thermoplastic polyimide obtained by polymerizing components, with an ether solvent ,
(B) including a step of applying a diluted polyamic acid solution on a substrate, and using an ether solvent having a saturated vapor pressure at 25 ° C. of 3 kPa to 25 kPa as a dilution solvent used in step (A). A method for coating a polyamic acid solution, which is characterized.