JP5589742B2 - Polyamic acid varnish, polyimide varnish, production method thereof, and connection structure - Google Patents

Description

  The present invention relates to a polyamic acid varnish or a polyimide varnish containing a fluororesin, or a production method thereof.

  Since the fluororesin film is excellent in characteristics such as heat resistance and chemical resistance, it has been attempted to use it as a cover film for a polyimide flexible substrate, for example. However, since the adhesiveness on the surface of the fluororesin film is very low, it has been very difficult to laminate a polyolefin film, a polyimide film, or the like on the fluororesin film with an adhesive. Therefore, it has been proposed to modify the surface of the fluororesin film by containing a light absorber such as aromatic polyester or aromatic polyamide and irradiating the surface with excimer laser light (Patent Document 1).

Japanese Patent Laid-Open No. 5-125208

  However, the operation of uniformly dispersing and mixing a light absorber in a fluororesin is not easy because the fluororesin and the polymer used as the light absorber are difficult to be compatible. Since the light irradiation apparatus is very expensive, there is a problem that the production cost of the fluororesin film including the mixing process of the light absorber and the modification process by the excimer laser irradiation becomes very expensive. It was. For this reason, a varnish that functions as an adhesive that exhibits good adhesion not only to the surface of a fluororesin that has not been subjected to such a modification treatment but also to a polyolefin or polyimide surface, and that exhibits excellent storage stability. It has been demanded.

  The object of the present invention is to solve the above-mentioned conventional problems, and is good not only for fluororesin surfaces not subjected to modification treatment such as excimer laser light irradiation but also for polyolefin and polyimide surfaces. It is to provide a varnish that exhibits excellent adhesiveness and excellent storage stability.

  The present inventors, as a component constituting a varnish used as an adhesive, under the technical common knowledge that if the same kind of material as that of the adherend is used, the adhesiveness is improved. In this case, the varnish was constituted by dissolving a fluorine-based resin and polyamic acid or polyimide in an organic solvent such as N-methyl-2-pyrrolidone (hereinafter, NMP). However, the adhesiveness of such a varnish to a fluorine-based resin is not sufficient, and there is a problem that phase separation occurs in the varnish under storage at room temperature. Therefore, the present inventors do not simply dissolve the fluororesin and polyamic acid or polyimide in an organic solvent, but polycondensate or polycondensate cyclize the acid dianhydride and diamine in the fluororesin solution. The varnish obtained by producing polyamic acid or polyimide by this method shows good adhesion not only to the surface of the fluororesin that has not been modified, but also to the surface of polyolefin and polyimide, and has excellent storage stability As a result, the present invention has been completed.

  That is, the present invention is a polyamic acid varnish containing a polyamic acid obtained by polycondensation of an acid dianhydride and a diamine, a fluororesin, and an organic solvent capable of dissolving them, the polyamic acid varnish. There is provided a polyamic acid varnish characterized in that an acid is produced by polycondensation of an acid dianhydride and a diamine in a fluorine resin solution obtained by dissolving the fluorine resin in an organic solvent. In addition, the present invention provides a method for producing this polyamic acid varnish by producing a polyamic acid by polycondensation of acid dianhydride and diamine in a fluorine resin solution obtained by dissolving a fluorine resin in an organic solvent. A method for producing a polyamic acid varnish is provided.

  Furthermore, the present invention is a polyimide varnish containing a polyimide formed by polycondensation cyclization of an acid dianhydride and a diamine, a fluororesin, and an organic solvent capable of dissolving them. The present invention provides a polyimide varnish characterized by being produced by polycondensation cyclization of acid dianhydride and diamine in a fluorine resin solution obtained by dissolving the fluorine resin in an organic solvent. Further, the present invention is characterized in that, as the polyimide, a polyimide is produced by polycondensation of acid dianhydride and diamine in a fluorine resin solution obtained by dissolving a fluorine resin in a polyamic acid organic solvent. A method for producing a polyimide varnish is provided.

  In addition, the present invention provides a bonded structure in which a polyimide adherend or polyolefin adherend and a fluorine-based adherend are bonded via an adhesive layer, wherein the adhesive layer is the polyamic acid varnish of the present invention described above. A connection structure is provided which is formed by imidizing or forming the above-described polyimide varnish of the present invention.

  The polyamic acid varnish or polyimide varnish of the present invention is prepared by polycondensation or polycondensation cyclization of acid dianhydride and diamine in a fluorine-based resin solution to produce polyamic acid or polyimide. For this reason, the polyamic acid varnish or the polyimide varnish of the present invention exhibits good adhesion to not only fluorine-based resins but also polyimide and polyolefin, and can also exhibit good storage stability.

<Polyamic acid varnish>
The polyamic acid varnish of the present invention contains a polyamic acid obtained by polycondensation of an acid dianhydride and a diamine, a fluorine resin, and an organic solvent capable of dissolving them. Here, this polyamic acid is produced by polycondensation of acid dianhydride and diamine in a fluororesin solution obtained by dissolving a fluororesin in a polyamic acid organic solvent.

  Thus, the polyamic acid varnish formed by polycondensation of acid dianhydride and diamine to produce a polyamic acid in a fluororesin solution in which a fluororesin is dissolved in an organic solvent is an adherend. The reason why the fluororesin, polyolefin or polyimide exhibits good adhesiveness and good storage stability is not clear, but is presumed to be due to good mixing and dispersion.

  If the number average molecular weight of the polyamic acid constituting the polyamic acid varnish of the present invention is too small, the film tends to be brittle, and if it is too large, the compatibility with the fluororesin tends to decrease. More preferably, it is 3000-70000. The molecular weight can be adjusted by adjusting the blending ratio of the total of the acid dianhydride and diamine (polyamic acid) and the fluororesin. As the blending ratio of the fluororesin is decreased, the number average molecular weight of the polyamic acid can be increased. The molecular weight can also be adjusted by controlling the molar ratio of acid dianhydride and diamine.

  In the polyamic acid varnish of the present invention, if the blending ratio of the polyamic acid is too small, the viscosity of the varnish tends to be excessively low, and if it is too large, the varnish tends to gel, preferably 3 to 40% by mass. More preferably, it is 5-30 mass%.

  In the polyamic acid varnish of the present invention, if the blending ratio of the fluororesin is too small, the viscosity of the varnish tends to be excessively low, and if it is too large, the varnish tends to gel, preferably 3 to 40 mass. %, More preferably 5 to 30% by mass.

  Further, the blending ratio (mass basis) of the fluorine-based resin (PF) with respect to the polyamic acid (PA) in the polyamic acid varnish tends to fail to obtain sufficient adhesion when the fluorine-based resin is too small relative to the polyamic acid. If the amount is too large, sufficient heat resistance tends not to be obtained, so PA: PF = 1: 6 to 6: 1 is preferable.

  In the polyamic acid varnish of the present invention, the blending ratio of the organic solvent capable of dissolving the fluororesin and the polyamic acid tends to gel if it is too small, and the viscosity of the varnish tends to be excessively low if it is too large. Since it exists, Preferably it is 60-94 mass%, More preferably, it is 70-90 mass%.

  Specific examples of the fluorine-based resin include the following compounds. Two or more of these can be used in combination.

Polytetrafluoroethylene (PTFE);
Tetrafluoroethylene-perfluoroalkyl vinyl ether (PFA);
Tetrafluoroethylene-hexafluoropropylene copolymer (FEP);
Polychlorotrifluoroethylene (PCTFE);
Tetrafluoroethylene / ethylene copolymer (ETFE);
Chlorotrifluoroethylene-ethylene copolymer (ECTFE);
Polyvinylidene fluoride (PVdF);
Vinylidene fluoride-hexafluoropropylene copolymer (PVdF-HFP); and polyvinyl fluoride (PVF).

  Among the above specific examples of the fluororesin, PVdF and PVdF-HFP can be preferably used from the viewpoint of versatility, and PvdF can be particularly preferably used.

  As the diamine and acid dianhydride constituting the polyamic acid, aromatic diamines and aromatic acid dianhydrides can be preferably used from the viewpoint of easy availability.

  Specific examples of the aromatic diamine include the following compounds. Two or more of these can be used in combination.

4,4'-diaminodiphenylmethane;
3,4'-diaminodiphenylmethane;
3,3'-diaminodiphenylmethane;
1,2-bis [4-aminophenoxy] ethane;
1,3-bis [4-aminophenoxy] propane;
1,4-bis [4-aminophenoxy] butane;
1,5-bis [4-aminophenoxy] pentane;
Di [2- (4-aminophenoxy) ethyl] ether;
1,2-bis [2- (4-aminophenoxy) ethoxy] ethane;
Di (2- (2- [4-aminophenoxy] ethoxy) ethyl) ether;
1,2-bis [4-aminophenyl] ethane;
Di (4-diamino-3methylphenyl) methane;
Di (4-diamino-3,5-dimethylphenyl) methane (MED);
Di (4-diamino-3-ethyl-5-methylphenyl) methane;
Di (4-diamino-3,5-diethylphenyl) methane;
4,4'-diaminodiphenyl ether;
1,4-diaminobenzene;
1,4-diamino-2,3,5,6-tetramethylbenzene;
2,2-bis (4- (4-aminophenoxy) phenyl) propane (BAPP);
2,2-bis (4- (4-aminophenoxy) phenyl) -1,1,1,3,3,3-hexafluoropropane (HFBAPP); and 1,8-diaminooctane.

  Among the specific examples of the aromatic diamines described above, HFBAPP containing fluorine and MED having an asymmetric structure can be preferably used from the viewpoint of improving solvent solubility, and MED can be particularly preferably used.

  Specific examples of the acid dianhydride include the following compounds. Two or more of these can be used in combination.

Pyromellitic dianhydride (PMDA);
Methyl pyromellitic dianhydride;
Dimethyl pyromellitic dianhydride;
Di (trifluoromethyl) pyromellitic dianhydride;
4,4 '-(hexafluoroisopropylidene) diphthalic dianhydride;
3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (s-BPDA);
5,5'-dimethyl-3,3 ', 4,4'-biphenyltetracarboxylic dianhydride;
p- (3,4-dicarboxyphenyl) benzene dianhydride;
3,3 ', 4,4'-tetracarboxydiphenyl ether dianhydride (s-ODPA);
2,3,3 ', 4'-tetracarboxydiphenyl ether dianhydride;
3,3 ', 4,4'-tetracarboxybenzophenone dianhydride;
1,4,5,8-tetracarboxynaphthalene dianhydride;
1,2,5,6-tetracarboxynaphthalene dianhydride;
3,3 ', 4,4'-tetracarboxydiphenylmethane dianhydride;
2,2-bis (3,4-dicarboxyphenyl) propane dianhydride;
2,2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride;
3,3 ', 4,4'-tetracarboxydiphenylsulfone dianhydride;
3,4,9,10-tetracarboxyperylene dianhydride;
3,3 ′, 4,4′-ethylene glycol bis (phenyl) tetracarboxylic dianhydride;
1,2,4,5-cyclohexanetetracarboxylic dianhydride;
1,2,3,4-cyclobutanetetracarboxylic dianhydride;
1,2,3,4-butanetetracarboxylic dianhydride;
9,9-bis (3,4-dicarboxyphenyl) fluorenic dianhydride (BPAF);
9,9-bis [4- (3,4-dicarboxyphenoxy) phenyl] fluorenic dianhydride.

  Among the specific examples of the above acid dianhydrides, PMDA can be preferably used from the viewpoint of availability.

  As an organic solvent which melt | dissolves the fluorine-type resin and polyamic acid mentioned above, it is necessary to melt | dissolve the acid dianhydride and diamine which are the raw materials of polyamic acid. Examples of such an organic solvent include N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, tetramethyl sulfone, 1,4-dioxane and the like. Two or more of these can be used in combination. Especially, NMP can be preferably used from the point of the melt | dissolution ability with respect to resin. If necessary, a solvent such as toluene for azeotropic removal of water produced by polycondensation can be used within a range not impairing the effects of the invention.

  The polyamic acid varnish of the present invention can be used as follows. For example, a polyamic acid varnish is applied to a polyolefin film or a polyimide film by a conventional method, a fluororesin film is laminated thereon, and the whole is pressurized to 3 to 50 MPa and heated to 80 to 220 ° C. to imidize ( By cyclization, the film can be converted into a polyimide layer while the polyolefin film or polyimide film and the fluororesin film are brought into close contact with each other.

<Method for preparing polyamic acid varnish>
The polyamic acid varnish of the present invention can be prepared by polycondensation of an acid dianhydride and a diamine to produce a polyamic acid in a fluorine resin solution obtained by dissolving a fluorine resin in an organic solvent.

Specifically, it is prepared by the following procedure.
1) 1 part by mass of a fluororesin is preferably dissolved in 5 to 20 parts by mass of an organic solvent such as NMP while heating as necessary to prepare a fluororesin solution.
2) The amount of acid dianhydride and diamine in which the polyamic acid is preferably 0.6 to 6 parts by mass with respect to 1 part by mass of the fluorine-based resin is added to the fluorine-based resin solution, preferably 5 to 20 parts by mass, respectively. A solution dissolved in an organic solvent such as NMP is mixed.
3) After confirming that the mixture has become a homogeneous solution, preferably polycondensation is advanced by heating to 20 to 120 ° C. for 0.5 to 10 hours to produce a polyamic acid. Thereby, the polyamic acid varnish which melt | dissolved fluororesin and polyamic acid is obtained.

<Polyimide varnish>
The polyimide varnish of the present invention contains a polyimide formed by polycondensation cyclization of acid dianhydride and diamine, a fluororesin, and an organic solvent capable of dissolving them. Here, this polyimide is produced by polycondensation cyclization of acid dianhydride and diamine in a fluorine resin solution obtained by dissolving a fluorine resin in a polyamic acid organic solvent. In other words, it corresponds to an imidized (cyclized) polyamic acid constituting the polyamic acid varnish of the present invention.

  Thus, a polyimide varnish formed by polycondensation cyclization of acid dianhydride and diamine to produce polyimide in a fluorine resin solution obtained by dissolving a fluorine resin in an organic solvent is an adherend. The reason for showing good adhesion to fluororesins, polyolefins or polyimides, and good storage stability is not clear, as in the case of polyamic acid varnish, but because the mixed and dispersed state is good. Guessed.

  If the number average molecular weight of the polyimide constituting the polyimide varnish of the present invention is too small, the formed film tends to be brittle, and if it is too large, the compatibility with the fluororesin tends to decrease. More preferably, it is 3000-70000. The molecular weight can be adjusted by adjusting the blending ratio of the total of the acid dianhydride and diamine (polyimide) and the fluororesin. As the blending ratio of the fluororesin is decreased, the number average molecular weight of the polyamic acid can be increased.

  In the polyimide varnish of the present invention, if the blending ratio of the polyimide is too small, the viscosity of the varnish tends to be excessively low, and if it is too large, it tends to gel, so preferably 3 to 40% by mass, more preferably It is 5-30 mass%.

  In the polyimide varnish of the present invention, if the blending ratio of the fluororesin is too small, the viscosity of the varnish tends to be excessively low, and if it is too large, it tends to gel, so preferably 3 to 40% by mass. Preferably it is 5-30 mass%.

  Further, the blending ratio (mass basis) of the fluororesin (PF) with respect to the polyimide (PI) in the polyimide varnish tends to fail to obtain sufficient adhesiveness when the fluororesin is too small relative to the polyimide, and too much. Since sufficient heat resistance tends not to be obtained, PI: PF = 1: 6 to 6: 1 is preferable.

  In the polyimide varnish of the present invention, the blending ratio of the organic solvent capable of dissolving the fluororesin and the polyimide tends to gel if it is too small, and if it is too large, the viscosity of the varnish tends to be excessively low. , Preferably it is 60-94 mass%, More preferably, it is 70-90 mass%.

  The fluorine-based resin constituting the polyimide varnish of the present invention, the acid dianhydride and diamine constituting the polyimide, and the organic solvent are the fluorine-based resin, acid dianhydride and diamine, organic, described in the polyamic acid varnish of the present invention. The structure similar to a solvent can be taken.

  The polyimide varnish of the present invention can be used as follows. For example, a polyimide varnish is applied to a polyolefin film or a polyimide film by a conventional method, a fluororesin film is laminated thereon, and the whole is pressurized to 3 to 50 MPa and heated to 80 to 120 ° C. A film or a polyimide film and a fluororesin film can be adhered.

<Method for preparing polyimide varnish>
The polyimide varnish of the present invention can be prepared by forming a polyimide by polycondensation cyclization of acid dianhydride and diamine in a fluorine resin solution obtained by dissolving a fluorine resin in an organic solvent such as NMP. .

Specifically, it is prepared by the following procedure.
1) 1 part by mass of a fluororesin is preferably dissolved in 5 to 20 parts by mass of an organic solvent such as NMP while heating as necessary to prepare a fluororesin solution.
2) The amount of acid dianhydride and diamine in which the polyimide is preferably 0.6 to 6 parts by mass with respect to 1 part by mass of the fluororesin in the fluororesin solution, preferably 5 to 20 parts by mass, respectively. A solution dissolved in an organic solvent is mixed.
3) After confirming that the mixture has become a uniform solution, preferably polycondensation is advanced by heating to 80 to 220 ° C. for 0.5 to 10 hours to produce a polyamic acid.
4) To the mixture containing polyamic acid, a water azeotropic removal solvent such as toluene for azeotropic removal of water is added as appropriate, and water is removed azeotropically, preferably while heating at 100 to 220 ° C. . Thereby, the polyimide varnish which melt | dissolved fluorine resin and a polyimide is obtained.

<Uses of polyamic acid varnish and polyimide varnish>
The polyamic acid varnish and polyimide varnish of the present invention described above are used as cover coating materials for various substrates such as polyimide flexible substrates, glass epoxy substrates, fluororesin substrates, and polyolefin or polyimide adherends such as polyolefin films and polyimide films. It is useful as an adhesive for bonding a fluororesin adherend such as a fluororesin film. Alternatively, it is also useful as an anchor coat material for using other adhesives. In particular, when used as an adhesive, a polyimide adherend or a polyolefin adherend and a fluororesin adherend are formed into a polyimide layer formed by imidizing the polyamic acid varnish of the present invention, or the polyimide varnish of the present invention. A connection structure that is well bonded with the polyimide layer on which is formed is provided. This connection structure is also part of the present invention.

Example 1 (Preparation of polyamic acid varnish, PA: PVdF = 1: 1)
In a nitrogen atmosphere, 450 g of an N-methyl-2-pyrrolidone (NMP) solution of 8 wt% polyvinylidene fluoride (PVdF) is charged into a 1000 ml separable four-necked flask equipped with a mechanical stirrer, a dropping funnel and a thermometer. did. Thereto, 20.2 g (71.6 mmol) of di (4-diamino-3,5-dimethylphenyl) methane (MED) and 200 g of NMP were added and stirred to dissolve MED. Subsequently, 15.8 g (72.4 mmol) of pyromellitic dianhydride (PMDA) and 428 g of NMP were added and stirred to dissolve PMDA.

  The resulting solution was heated and stirred at 80 ° C. for 2 hours to polycondense MED and PMDA to obtain a polyamic acid varnish.

Example 2 (Preparation of polyimide varnish, PI: PVdF = 1: 1)
By repeating the operation of Example 1, a polyamic acid varnish was obtained. Further, 50 g of toluene was added, and the polyamic acid was imidized (cyclized) by heating and stirring at 195 ° C. for 3 hours. At that time, the produced water was removed while azeotropically removing with toluene. After completion of the heating, toluene and remaining water were distilled off under reduced pressure to obtain a polyimide varnish. The number average molecular weight of the polyimide contained in this polyimide varnish was 23800.

Example 3 (Preparation of polyimide varnish, PI: PVdF = 1: 2)
In a nitrogen atmosphere, 267 g of an 8 wt% PVdF NMP solution was charged into a 500 ml separable four-necked flask equipped with a mechanical stirrer, a dropping funnel and a thermometer. Then, 5.97 g (21.1 mmol) of MED and 100 g of NMP were added and stirred to dissolve MED. Subsequently, 4.67 g (21.4 mmol) of PMDA and 122 g of NMP were added and stirred to dissolve PMDA.

  The resulting solution was heated and stirred at 80 ° C. for 2 hours to polycondense MED and PMDA to obtain a polyamic acid varnish. Further, 30 g of toluene was added, and the mixture was heated and stirred at 195 ° C. for 3 hours to obtain a polyamic acid varnish. The acid was imidized (cyclized). At that time, the produced water was removed while azeotropically removing with toluene. After completion of the heating, toluene and remaining water were distilled off under reduced pressure to obtain a polyimide varnish.

Example 4 (Preparation of polyimide varnish, PI: PVdF = 1: 5)
In a nitrogen atmosphere, 334 g of an 8 wt% PVdF NMP solution was charged into a 500 ml separable four-necked flask equipped with a mechanical stirrer, a dropping funnel and a thermometer. Thereto, 2.96 g (10.48 mmol) of MED and 20 g of NMP were added and stirred to dissolve the MED. Subsequently, 2.32 g (10.6 mmol) of PMDA and 41 g of NMP were added and stirred to dissolve the PMDA.

  The resulting solution was heated and stirred at 80 ° C. for 2 hours to polycondense MED and PMDA to obtain a polyamic acid varnish. Further, 30 g of toluene was added, and the mixture was heated and stirred at 195 ° C. for 3 hours to obtain a polyamic acid varnish. The acid was imidized (cyclized). At that time, the produced water was removed while azeotropically removing with toluene. After completion of the heating, toluene and remaining water were distilled off under reduced pressure to obtain a polyimide varnish.

Example 5 (Preparation of polyimide varnish, PI: PVdF = 2: 1)
In a nitrogen atmosphere, 133 g of 8 wt% PVdF NMP solution was charged into a 500 ml separable four-necked flask equipped with a mechanical stirrer, a dropping funnel and a thermometer. MED12.0g (42.45mmol) and NMP100g were thrown in there, and it stirred and dissolved MED. Subsequently, 9.37 g (42.3 mmol) of PMDA and 145 g of NMP were added and stirred to dissolve PMDA.

  The resulting solution was heated and stirred at 80 ° C. for 2 hours to polycondense MED and PMDA to obtain a polyamic acid varnish. Further, 50 g of toluene was added, and the mixture was heated and stirred at 195 ° C. for 3 hours to obtain a polyamic acid varnish. The acid was imidized (cyclized). At that time, the produced water was removed while azeotropically removing with toluene. After completion of the heating, toluene and remaining water were distilled off under reduced pressure to obtain a polyimide varnish. The number average molecular weight of the polyimide contained in this polyimide varnish was 39300.

Example 6 (Preparation of polyimide varnish, PI: PVdF = 5: 1)
Under a nitrogen atmosphere, 67 g of an 8 wt% PVdF NMP solution was charged into a 500 ml separable four-necked flask equipped with a mechanical stirrer, a dropping funnel and a thermometer. MED15.0g (53.0mmol) and NMP150g were thrown in there, and it stirred and dissolved MED. Subsequently, 11.48 g (52.6 mmol) of PMDA and 156 g of NMP were added and stirred to dissolve PMDA.

  The resulting solution was heated and stirred at 80 ° C. for 2 hours to polycondense MED and PMDA to obtain a polyamic acid varnish. Further, 50 g of toluene was added, and the mixture was heated and stirred at 195 ° C. for 3 hours to obtain a polyamic acid varnish. The acid was imidized (cyclized). At that time, the produced water was removed while azeotropically removing with toluene. After completion of the heating, toluene and remaining water were distilled off under reduced pressure to obtain a polyimide varnish. The number average molecular weight of the polyimide contained in this polyimide varnish was 47267.

Comparative Example 1 (Preparation of polyimide varnish, PA: PVdF = 1: 0)
Under a nitrogen atmosphere, in a 1000 ml separable four-necked flask equipped with a mechanical stirrer, a dropping funnel and a thermometer, 40.4 g (143.2 mmol) of di (4-diamino-3,5-dimethylphenyl) methane (MED) was added. ) And 400 g of NMP were added and stirred to dissolve MED. Subsequently, 31.6 g (144.7 mmol) of pyromellitic dianhydride (PMDA) and 428 g of NMP were added and stirred to dissolve PMDA.

  The resulting solution was heated and stirred at 80 ° C. for 2 hours to polycondense MED and PMDA to obtain a polyamic acid varnish. Further, 50 g of toluene was added, and the mixture was heated and stirred at 195 ° C. for 3 hours to obtain a polyamic acid varnish. The acid was imidized (cyclized). At that time, the produced water was removed while azeotropically removing with toluene. After completion of the heating, toluene and remaining water were distilled off under reduced pressure to obtain a polyimide varnish containing no fluororesin.

Comparative Example 2 (Preparation of polyimide varnish, kneading type)
10 g of the polyimide varnish obtained in Comparative Example 1 and 10 g of NMP solution of 8 wt% PVdF were put into a sample bottle, 6 g of glass beads were added, and a rotating / revolving mixer (Awatake Rentaro AR-250, Shinky Co., Ltd.) The polyimide varnish was obtained by mixing for 6 minutes.

Comparative Example 3 (Preparation of polyimide varnish, kneading type)
A polyimide varnish was obtained by putting 10 g of the polyimide varnish obtained in Comparative Example 1 and 10 g of an NMP solution of 8 wt% PVdF into a sample bottle and mixing them at room temperature using a jar mill.

<Evaluation>
(Storage stability evaluation)
The varnishes of the examples and comparative examples were allowed to stand at room temperature, and the presence or absence of a phase-separated polyimide phase or PVdf phase was visually observed at 1, 10, 25, and 28 days after leaving. The case where phase separation was observed was evaluated as “NG (poor)”, and the case where phase separation was not observed was evaluated as “G (good)”. The obtained results are shown in Table 1.

(Adhesion evaluation)
The varnish of each example and each comparative example was placed on one side of a flat glass plate (length 200 mm, width 200 mm, thickness 5 mm) so that the PVdF-containing polyimide film (PI film) after drying had a thickness of 10 μm. Cast and dried at 100 ° C. for 10 minutes. In addition, in the case of Example 1, it is a PVdF containing polyamic acid film | membrane, and in the case of the comparative example 1, it is a PVdF non-containing polyimide film | membrane.

  Similarly, an NMP solution of 8 wt% PVdF was cast on one side of a flat glass plate (length 200 mm, width 200 mm, thickness 5 mm) so that the film thickness of the PVdF film after drying was 10 μm, and 100 ° C. For 10 minutes.

The glass plates were overlapped so that the PI film (PA film) and the PVdF film faced ^each other, and were bonded using a hot press apparatus under the conditions of a heating temperature of 100 ° C., a heating and pressing time of 60 seconds, and a pressure of 0.89 kgf / cm ² . . In addition, in the case of Example 1, since imidation was accompanied, it bonded on the conditions of the heating temperature of 200 degreeC, the thermocompression bonding time for 30 minutes, and the pressure of 2 MPa. After leaving to cool to room temperature, when two glass plates are peeled off with fingers, the case where the film can be peeled without resistance between the PI film (PA film) and the PVdF film is “NG (defect)” The case where resistance was felt was evaluated as “G (good)”. The obtained results are shown in Table 1.

  As can be seen from Table 1, Comparative Example 1 is a case where a polyimide varnish not containing PVdF was used, and there was no problem in storage stability, but the adhesiveness was NG in the first place. Comparative Examples 2 and 3 are examples in which polyimide was not produced in a PVdF solution, but PVdF and PI were mixed using a normal mixing apparatus, but the adhesion evaluation was NG, and one day after mixing. The storage stability at the time was also NG.

  On the other hand, when the varnishes of Examples 1 to 6 were used, both storage stability and adhesiveness were G evaluations, which was a preferable result. In addition, when the molecular weight of the polyimide produced | generated by the polycondensation cyclization in DVdF becomes large (refer Example 2, 5, 6), it turns out that long-term storage stability tends to fall. It can also be seen that the molecular weight of the PI to be generated can be reduced by reducing the ratio of PI to PVdF.

  The polyamic acid varnish or polyimide varnish of the present invention exhibits good adhesion to not only fluorine-based resins but also polyimide and polyolefin, and can also exhibit good storage stability. For this reason, the polyamic acid varnish or the polyimide varnish of the present invention is used as a cover coat material for various substrates such as a polyimide flexible substrate, a glass epoxy substrate, a fluororesin substrate, or a polyolefin or polyimide adherend such as a polyolefin film or a polyimide film. It is useful as an adhesive for bonding a fluororesin adherend such as a fluororesin film.

Claims (17)

  A polyamic acid varnish containing a polyamic acid obtained by polycondensation of an acid dianhydride and a diamine, a fluororesin, and an organic solvent capable of dissolving them, wherein the polyamic acid is the fluorochemical A polyamic acid varnish produced by polycondensation of an acid dianhydride and a diamine in a fluororesin solution obtained by dissolving a resin in an organic solvent.   The content of the polyamic acid in the polyamic acid varnish is 3 to 40% by mass, the content of the fluororesin is 3 to 40% by mass, and the content ratio (mass basis) of the polyamic acid and the fluororesin is The polyamic acid varnish according to claim 1, which is 1: 6 to 6: 1.   The polyamic acid varnish according to claim 1 or 2, wherein the polyamic acid has a number average molecular weight of 1,000 to 100,000. The diamine constituting the polyamic acid is:
4,4'-diaminodiphenylmethane;
3,4'-diaminodiphenylmethane;
3,3′-diaminodiphenylmethane;
1,2-bis [4-aminophenoxy] ethane;
1,3-bis [4-aminophenoxy] propane;
1,4-bis [4-aminophenoxy] butane;
1,5-bis [4-aminophenoxy] pentane;
Di [2- (4-aminophenoxy) ethyl] ether;
1,2-bis [2- (4-aminophenoxy) ethoxy] ethane;
Di (2- (2- [4-aminophenoxy] ethoxy) ethyl) ether;
1,2-bis [4-aminophenyl] ethane;
Di (4-diamino-3methylphenyl) methane;
Di (4-diamino-3,5-dimethylphenyl) methane (MED);
Di (4-diamino-3-ethyl-5-methylphenyl) methane;
Di (4-diamino-3,5-diethylphenyl) methane;
4,4′-diaminodiphenyl ether;
1,4-diaminobenzene;
1,4-diamino-2,3,5,6-tetramethylbenzene;
2,2-bis (4- (4-aminophenoxy) phenyl) propane (BAPP);
At least one selected from 2,2-bis (4- (4-aminophenoxy) phenyl) -1,1,1,3,3,3-hexafluoropropane (HFBAPP); and 1,8-diaminooctane There are acid dianhydrides:
Pyromellitic dianhydride (PMDA);
Methyl pyromellitic dianhydride;
Dimethyl pyromellitic dianhydride;
Di (trifluoromethyl) pyromellitic dianhydride;
4,4 ′-(hexafluoroisopropylidene) diphthalic dianhydride;
3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (s-BPDA);
5,5′-dimethyl-3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride;
p- (3,4-dicarboxyphenyl) benzene dianhydride;
3,3 ′, 4,4′-tetracarboxydiphenyl ether dianhydride (s-ODPA);
2,3,3 ′, 4′-tetracarboxydiphenyl ether dianhydride;
3,3 ′, 4,4′-tetracarboxybenzophenone dianhydride;
1,4,5,8-tetracarboxynaphthalene dianhydride;
1,2,5,6-tetracarboxynaphthalene dianhydride;
3,3 ′, 4,4′-tetracarboxydiphenylmethane dianhydride;
2,2-bis (3,4-dicarboxyphenyl) propane dianhydride;
2,2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride;
3,3 ′, 4,4′-tetracarboxydiphenylsulfone dianhydride;
3,4,9,10-tetracarboxyperylene dianhydride;
3,3 ′, 4,4′-ethylene glycol bis (phenyl) tetracarboxylic dianhydride;
1,2,4,5-cyclohexanetetracarboxylic dianhydride;
1,2,3,4-cyclobutanetetracarboxylic dianhydride;
1,2,3,4-butanetetracarboxylic dianhydride;
Selected from 9,9-bis (3,4-dicarboxyphenyl) fluorenic dianhydride (BPAF); and 9,9-bis [4- (3,4-dicarboxyphenoxy) phenyl] fluorenic dianhydride The polyamic acid varnish according to any one of claims 1 to 3, which is at least one kind.   The polyamic acid according to any one of claims 1 to 3, wherein the diamine constituting the polyamic acid is di (4-diamino-3,5-dimethylphenyl) methane, and the acid anhydride is pyromellitic dianhydride. varnish. Fluorine resin:
Polytetrafluoroethylene (PTFE);
Tetrafluoroethylene-perfluoroalkyl vinyl ether (PFA);
Tetrafluoroethylene-hexafluoropropylene copolymer (FEP);
Polychlorotrifluoroethylene (PCTFE);
Tetrafluoroethylene / ethylene copolymer (ETFE);
Chlorotrifluoroethylene-ethylene copolymer (ECTFE);
Polyvinylidene fluoride (PVdF);
Vinylidene fluoride-hexafluoropropylene copolymer (PVdF-HFP); and polyvinyl fluoride (PVF)
The polyamic acid varnish according to claim 1, which is at least one selected from the group consisting of:   The polyamic acid varnish according to claim 1, wherein the fluororesin is polyvinylidene fluoride (PVdF).   A method for producing a polyamic acid varnish according to any one of claims 1 to 7, wherein an acid dianhydride and a diamine are polycondensed in a fluororesin solution obtained by dissolving a fluororesin in an organic solvent. The manufacturing method of the polyamic acid varnish characterized by producing | generating an acid.   A polyimide varnish containing a polyimide formed by polycondensation cyclization of an acid dianhydride and a diamine, a fluorine resin, and an organic solvent capable of dissolving them, the polyimide comprising the fluorine resin A polyimide varnish produced by polycondensation cyclization of acid dianhydride and diamine in a fluororesin solution dissolved in an organic solvent.   The content of the polyimide in the polyimide varnish is 3 to 40% by mass, the content of the fluororesin is 3 to 40% by mass, and the content ratio (mass basis) of the polyimide and the fluororesin is 1: 6. The polyimide varnish according to claim 9, which is ˜6: 1.   The polyimide varnish according to claim 9 or 10, wherein the number average molecular weight of the polyimide is 1000 to 100,000. The diamine that composes the polyimide is:
4,4'-diaminodiphenylmethane;
3,4'-diaminodiphenylmethane;
3,3′-diaminodiphenylmethane;
1,2-bis [4-aminophenoxy] ethane;
1,3-bis [4-aminophenoxy] propane;
1,4-bis [4-aminophenoxy] butane;
1,5-bis [4-aminophenoxy] pentane;
Di [2- (4-aminophenoxy) ethyl] ether;
1,2-bis [2- (4-aminophenoxy) ethoxy] ethane;
Di (2- (2- [4-aminophenoxy] ethoxy) ethyl) ether;
1,2-bis [4-aminophenyl] ethane;
Di (4-diamino-3methylphenyl) methane;
Di (4-diamino-3,5-dimethylphenyl) methane (MED);
Di (4-diamino-3-ethyl-5-methylphenyl) methane;
Di (4-diamino-3,5-diethylphenyl) methane;
4,4′-diaminodiphenyl ether;
1,4-diaminobenzene;
1,4-diamino-2,3,5,6-tetramethylbenzene;
2,2-bis (4- (4-aminophenoxy) phenyl) propane (BAPP);
At least one selected from 2,2-bis (4- (4-aminophenoxy) phenyl) -1,1,1,3,3,3-hexafluoropropane (HFBAPP); and 1,8-diaminooctane There are acid dianhydrides:
Pyromellitic dianhydride (PMDA);
Methyl pyromellitic dianhydride;
Dimethyl pyromellitic dianhydride;
Di (trifluoromethyl) pyromellitic dianhydride;
4,4 ′-(hexafluoroisopropylidene) diphthalic dianhydride;
3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (s-BPDA);
5,5′-dimethyl-3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride;
p- (3,4-dicarboxyphenyl) benzene dianhydride;
3,3 ′, 4,4′-tetracarboxydiphenyl ether dianhydride (s-ODPA);
2,3,3 ′, 4′-tetracarboxydiphenyl ether dianhydride;
3,3 ′, 4,4′-tetracarboxybenzophenone dianhydride;
1,4,5,8-tetracarboxynaphthalene dianhydride;
1,2,5,6-tetracarboxynaphthalene dianhydride;
3,3 ′, 4,4′-tetracarboxydiphenylmethane dianhydride;
2,2-bis (3,4-dicarboxyphenyl) propane dianhydride;
2,2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride;
3,3 ′, 4,4′-tetracarboxydiphenylsulfone dianhydride;
3,4,9,10-tetracarboxyperylene dianhydride;
3,3 ′, 4,4′-ethylene glycol bis (phenyl) tetracarboxylic dianhydride;
1,2,4,5-cyclohexanetetracarboxylic dianhydride;
1,2,3,4-cyclobutanetetracarboxylic dianhydride;
1,2,3,4-butanetetracarboxylic dianhydride;
Selected from 9,9-bis (3,4-dicarboxyphenyl) fluorenic dianhydride (BPAF); and 9,9-bis [4- (3,4-dicarboxyphenoxy) phenyl] fluorenic dianhydride polyimide varnish according to any one of claims 9 to 11 is at least one.
  The polyimide varnish according to any one of claims 9 to 12, wherein the diamine constituting the polyimide is di (4-diamino-3,5-dimethylphenyl) methane, and the acid anhydride is pyromellitic dianhydride. Fluorine resin:
Polytetrafluoroethylene (PTFE);
Tetrafluoroethylene-perfluoroalkyl vinyl ether (PFA);
Tetrafluoroethylene-hexafluoropropylene copolymer (FEP);
Polychlorotrifluoroethylene (PCTFE);
Tetrafluoroethylene / ethylene copolymer (ETFE);
Chlorotrifluoroethylene-ethylene copolymer (ECTFE);
Polyvinylidene fluoride (PVdF);
Vinylidene fluoride-hexafluoropropylene copolymer (PVdF-HFP); and polyvinyl fluoride (PVF)
The polyimide varnish according to claim 9, which is at least one selected from the group consisting of:   The polyimide varnish according to any one of claims 9 to 13, wherein the fluororesin is polyvinylidene fluoride (PVdF).   The method for producing a polyimide varnish according to any one of claims 9 to 15, wherein an acid dianhydride and a diamine are polycondensed and cyclized in a fluorine resin solution obtained by dissolving a fluorine resin in an organic solvent. A method for producing a polyimide varnish, wherein   The bonded structure in which the polyimide adherend or polyolefin adherend and the fluororesin adherend are bonded via an adhesive layer, the adhesive layer is the polyamic acid varnish according to any one of claims 1 to 8. A connection structure formed by forming a polyimide varnish according to any one of claims 9 to 15 into a film.