JP6997493B2 - Method for manufacturing polyimide powder - Google Patents

Description

The present invention relates to a method for producing polyimide (hereinafter, may be abbreviated as "PI") powder.

Among the PIs, the soluble PI having good solubility in a solvent is used for manufacturing, for example, heat-resistant insulating tape, heat-resistant adhesive tape, high-density magnetic recording base, capacitor, film for FPC and the like. Further, for example, it is used for manufacturing molding materials and molded products such as sliding members filled with fluororesin and graphite, structural members reinforced with glass fiber and carbon fiber, bobbins and sleeves of small coils, and tubes for terminal insulation. .. It is also used in the manufacture of laminated materials such as insulating spacers for power transistors, magnetic head spacers, spacers for power relays, and spacers for transformers. It is also used in the manufacture of enamel coating materials for electric wire / cable insulation coatings, solar cells, low temperature storage tanks, space insulation materials, integrated circuits, slot liners, and the like. It is also used in the production of ultrafiltration membranes, reverse osmosis membranes, and gas separation membranes. It is also used in the production of heat-resistant threads, woven fabrics, non-woven fabrics and the like. Further, since it is less colored and has excellent transparency of visible light, it is also used as an optical waveguide, a liquid crystal substrate, a liquid crystal alignment film, an optical component protective film, and the like. Further, it has been proposed as a binder for electrodes of lithium secondary batteries and the like. These soluble PIs are generally prepared by adding a co-boiling solvent such as xylene to a polyamic acid solution obtained by reacting tetracarboxylic acid dianhydride and diamine in an amide-based solvent, heating the mixture, and distilling off water. It is produced by advancing the imidization reaction while obtaining a PI solution, adding a poor solvent such as alcohol to the PI solution, reprecipitating the PI, filtering it, and drying it. (For example, Patent Documents 1 and 2)

Since the above method carries out polymerization in a solution state, a considerable amount of organic solvent is required, and further solvent needs to be used for isolating PI, which is preferable from the viewpoint of environmental compatibility. It wasn't a method. In order to deal with this problem, a method for producing PI by a solid phase polymerization method has been proposed. For example, Patent Document 3 proposes a method for producing crystalline PI powder by performing solid-phase polymerization in a large amount of solvent. Further, Patent Document 4 proposes a method for producing crystalline PI by performing solid-phase polymerization in a state where a solvent does not coexist. Further, in Patent Document 5, a nylon salt type monoma is subjected to solid phase polymerization in a state where a solvent does not coexist, and then suspended polymerization is carried out in a poor solvent at a temperature higher than the solid phase polymerization temperature to achieve crystallinity. A method for producing PI powder has been proposed.

Japanese Unexamined Patent Publication No. 2000-319388 JP-A-2007-254615 Japanese Unexamined Patent Publication No. 7-33875 Japanese Unexamined Patent Publication No. 2004-27137 Japanese Unexamined Patent Publication No. 2012-92262

However, since all of the PIs obtained by the known solid phase polymerization methods are crystalline, they are insoluble in general-purpose solvents such as amide-based solvents. Therefore, its scope of application was significantly limited. Further, although the methods disclosed in Patent Documents 3 and 5 are solid-phase polymerization methods, a large amount of solvent is required for the PI to be produced during solid-phase polymerization, and the environmental compatibility is not good.

Therefore, an object of the present invention is to solve the above-mentioned problems and to provide a powder for obtaining PI powder soluble in a general-purpose solvent such as an amide solvent by solid phase polymerization.

It has been found that the above-mentioned problems can be solved by performing solid-phase polymerization using a powder having a specific composition, and the present invention has been completed.

The present invention has the following object.
<1> Solid-phase polymerization of a salt composed of tetracarboxylic acid or tetracarboxylic acid diester and substantially equimolar diamine in the presence of a solvent of 1% by mass or more and 30% by mass or less with respect to the mass of this salt. A method for producing a polyimide powder which is soluble in an amide solvent and has a weight average molecular weight of 10,000 or more by GPC.

The PI powder obtained by the present invention is soluble in an amide-based solvent, and the PI film obtained from this PI powder has excellent heat resistance and good mechanical properties. It can be suitably used in various applications. Further, the method for producing PI powder of the present invention is excellent in environmental compatibility because it does not use a large amount of solvent.

Hereinafter, the present invention will be described in detail.

The PI powder obtained by the present invention is soluble in an amide solvent. PI is a heat-resistant polymer having an imide bond in the main chain, and is usually obtained by polycondensing a diamine component, which is a monoma component, and a tetracarboxylic acid component. These PIs also include PI-modified products such as polyamide-imide (PAI) and polyesterimide (PEI). Here, the "PI soluble in an amide solvent" means a PI having a solubility in an amide solvent at 25 ° C. of 1% by mass or more. By doing so, the solution obtained by dissolving PI powder in an amide-based solvent can be used for the above-mentioned various uses. Specific examples of the amide-based solvent include N-methyl-2-pyrrolidone (NMP), N, N-dimethylformamide, N, N-dimethylacetamide (DMAc) and the like. The crystallinity of these PIs is not limited, but is preferably amorphous. The amorphousness of PI can be confirmed by measuring DSC (Differential Thermal Analysis). That is, if the melting point or the melting peak is not detected in the DSC curve obtained by measuring the DSC of the PI powder, it can be determined to be amorphous.

Further, the PI powder obtained by the present invention has Mw of 10,000 or more. Here, as Mw, a polystyrene-equivalent value measured under the following GPC measurement conditions can be used.
<GPC measurement conditions>
Column: GL-S300MDT-5 manufactured by Hitachi Kasei Co., Ltd.
Eluent: THF-DMF equivalent mixture (including 60 mM phosphoric acid and 30 mM lithium bromide)
Temperature: 25 ° C
Flow rate: 1.0 mL / min Detector: Differential refractometer Here, Mw is preferably 20,000 or more, and more preferably 30,000 or more. By doing so, the PI powder is dissolved in an amide-based solvent to form a solution, and when used for the various uses described above, good mechanical properties of the film or film obtained by casting the solution are ensured. be able to.

The glass transition temperature of the PI powder obtained by the present invention is preferably 150 ° C. or higher, more preferably 200 ° C. or higher. Here, the glass transition temperature refers to a value measured by DSC. By doing so, when the PI powder obtained by the present invention is dissolved in an amide-based solvent to form a solution and used for the above-mentioned various uses, good heat resistance of the film or coating can be ensured. ..

In the present invention, the PI powder is obtained by a solid phase polymerization method. Here, the solid phase polymerization method is a method for advancing the polymerization reaction in a solid state. Specifically, for example, a salt composed of a tetracarboxylic acid or a tetracarboxylic acid diester and a diamine is added to the mass of this salt. PI powder can be obtained by solid-phase polymerization by heating in the presence of a solvent of 1% by mass or more and 30% by mass or less. Hereinafter, the method for producing PI powder by the solid phase polymerization method will be described in detail.

In the solid phase polymerization, first, a salt composed of a tetracarboxylic acid or a tetracarboxylic acid diester which is an acid component and a diamine component is formed. Here, the tetracarboxylic acid diester refers to a tetracarboxylic acid dimethyl ester, a tetracarboxylic acid diethyl ester, a tetracarboxylic acid diisopropyl ester, or the like.

As the acid component, cyclobutane-1,2,3,4-tetracarboxylic acid, cyclopentane-1,2,3,4-tetracarboxylic acid, cyclohexane-1,2,4,5-tetracarboxylic acid (H-). PMA), pyromellitic acid (PMA), 3,3', 4,4'-diphenylsulfone tetracarboxylic acid, 3,3', 4,4'-benzophenone tetracarboxylic acid, 3,3', 4,4' -Biphenyltetracarboxylic acid (BPA), naphthalene-1,4,5,8-tetracarboxylic acid, 4,4'-oxydiphthalic acid, 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane (6) -FA), 2,2'-bis (trifluoromethyl) -4,4', 5,5'-biphenyltetracarboxylic acid, 4,4'-(hexafluorotrimethylene) -diphthalic acid, 4,4' -(Octafluorotetramethylene) -diphthalic acid, ethylene glycol bistrimeritate (TMEG), diethylene glycol bistrimeritate, triethylene glycol bistrimeritate, tetraethylene glycol bistrimerite, polyethylene glycol bistrimeritate, ethylene glycol bistrimeritamide , Diethylene glycol bistrimerid amide, triethylene glycol bistrimeric amide, tetraethylene glycol bistrimeric amide, polyethylene glycol bistrimeritate, propylene glycol bistrimerite, dipropylene glycol bistrimerite, tripropylene glycol bistrimerite, tetrapropylene glycol bistrite Tetracarboxylic acids such as melitate, polypropylene glycol bistrimeritate, propylene glycol bistrimeridamide, dipropylene glycol bistrimerid amide, tripropylene glycol bistrimertic amide, tetrapropylene glycol bistrimertic amide, polypropylene glycol bistrimerid amide, and these. Diester can be mentioned. These may be used alone or in combination of two or more. Among these, H-PMA, PMA, BPA, 6-FA and diesters thereof can be mentioned as preferable examples. An oligoma having a tetracarboxylic acid terminal obtained from an excess acid component and a diamine can also be used as the tetracarboxylic acid.

Examples of the diamine include 1,4-phenylenediamine, 1,3-phenylenediamine, 2,4-toluenediamine, 4,4'-diaminodiphenyl ether (DADE), 3,4'-diaminodiphenyl ether, 4, 4'-Diaminodiphenylmethane, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, α, α'- Bis (4-aminophenyl) 1,4-diisopropylbenzene, α, α'-bis (3-aminophenyl) -1,4-diisopropylbenzene, 2,2-bis [4- (4-aminophenoxy) phenyl] Propane (BAPP), 4,4'-diaminodiphenyl sulfone, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] sulfone, 2,6-diaminonaphthalene, 1 , 5-Diaminonaphthalene, ethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, decanediamine, dodecanediamine, polyethylene glycol bis (3-aminopropyl) ether, polypropylene glycol bis (3-aminopropyl) ether, 1, 3-Bis (aminomethyl) cyclohexane (AMC), 1,4-bis (aminomethyl) cyclohexane, p-xylylene diamine, m-xylylene diamine, siloxane diamines, 4,4'-diaminodicyclohexylmethane, 4, 4'-Methylenebis (2-methylcyclohexylamine), isophoronediamine (IPDA), norbornandiamine, bis (aminomethyl) tricyclo [5.2.1.02,6] decane, 2,2-bis (4-aminophenyl) ) Hexafluoropropane, 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane (6F-BAPP), 2-Trifluoromethyl-p-phenylenediamine, ethylene glycol bis (2-aminoethyl) ether, diamine glycol bis (2-aminoethyl) ether, triethylene glycol bis (2-aminoethyl) ether, tetraethylene glycol bis (2) -Aminoethyl) ether, polyethylene glycol bis (2-aminoethyl) ether, propylene glycol bis (2-aminoethi) Le) Ether, Dipropylene Glycolbis (2-Aminoethyl) Ether, Tripropylene Glycolbis (2-Aminoethyl) Ether, Tetrapropylene Glycolbis (2-Aminoethyl) Ether, Polypropylene Glycolbis (2-Aminoethyl) Ether (PGAE) and the like can be mentioned. These may be used alone or in combination of two or more. Among these, DADE, BAPP, AMC, IPDA, 6F-BAPP, PGAE and the like can be mentioned as preferable examples. An oligoma having a diamine terminal obtained from an acid component and an excess of diamine can also be used as a diamine.

Next, a solvent is added to the above-mentioned tetracarboxylic acid or tetracarboxylic acid diester and a salt composed of substantially equimolar diamine (hereinafter, may be simply abbreviated as "salt"), and the mixture is uniformly mixed. , The powder is moistened with a solvent. After doing so, the next solid-phase polymerization reaction is carried out. In the present invention, it is preferable to allow a solvent of 1% by mass or more and 30% by mass or less, preferably 2 to 20% by mass, coexist with the salt with respect to the mass of the salt. The solvent used here is a solvent capable of dissolving PI powder produced by solid phase polymerization, and specifically, a general-purpose solvent such as an amide-based solvent, an ether-based solvent, an ester-based solvent, and a ketone-based solvent. The amide-based solvent is preferable. As the amide-based solvent, the above-mentioned N-methyl-2-pyrrolidone (NMP), N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAc) and the like can be used, and among these, N-methyl-2-pyrrolidone (DMAc) and the like can be used. NMP and DMAc are preferred. At the time of the mixing, pulverization may be performed if necessary. Further, a powder may be produced by preparing a salt solution, evaporating most of the solvent of this solution, and then pulverizing the residue containing 1% by mass or more and 30% by mass or less of the solvent. The average particle size of the powder obtained by pulverization (the average particle size based on the volume by the laser diffraction method) is preferably 1 to 1000 μm. If the average particle size is less than 1 μm, the solvent may volatilize faster than the polymerization reaction during solid phase polymerization, making it difficult to obtain PI powder with a high degree of polymerization. If the average particle size exceeds 1000 μm, the uniform solid-phase polymerization reaction may not proceed.

The solid phase polymerization reaction is carried out by heating this powder. In the process of this polymerization reaction, the plasticizing effect on the salt or the generated PI is exhibited by the action of the solvent contained in the powder, and the polymerization reaction proceeds smoothly in the solid phase state.

The heating temperature is preferably in the range of 100 to 300 ° C, more preferably 120 to 250 ° C.

The atmosphere during heating is preferably an inert gas atmosphere such as nitrogen gas.

During heating, it is preferable to carry out a solid-phase polymerization reaction under normal pressure or pressure so as not to volatilize the solvent. Further, during the polymerization, the polymerization reaction may be carried out under stirring so that blocking does not occur in the powder or the generated PI. When the reaction is carried out under pressure, the solvent remaining in the reaction vessel and water, which is a by-product of the polymerization reaction, are removed by releasing the pressure after the polymerization reaction is completed, and the average particle size is 1 to 1 to 1. A powder of PI of 1000 μm can be obtained. The average particle size is preferably 5 to 500 μm, more preferably 10 to 300 μm.

By further heating the PI powder obtained as described above in a nitrogen gas stream or under reduced pressure, the polymerization reaction can be further promoted in the solid phase to further increase the molecular weight of PI. The heating temperature at this time is preferably 200 to 250 ° C. It is preferable that no solvent remains in the obtained PI powder, but it may remain in a trace amount that does not affect various characteristics of PI.

In the polymerization reaction, the degree of polymerization of PI produced can be adjusted by appropriately using an end-capping agent such as phthalic anhydride or aniline.

Hereinafter, the present invention will be described in more detail based on Examples, but the present invention is not limited to these Examples.

[Example 1]
To 1.0 mol of BPA (acid component), 0.7 mol of IPDA (diamine component) and 0.3 mol of BAPP (diamine component) were added and mixed at room temperature to obtain a salt. Next, 10% by mass of NMP was added to the mass of this salt, and the mixture was uniformly mixed and crushed to obtain a powder for PI solid phase polymerization (average particle size 250 μm). This PI solid phase polymerization powder was subjected to a solid phase polymerization reaction at 160 ° C. for 2 hours and at 230 ° C. for 2 hours in a pressure resistant reactor with a stirring blade substituted with nitrogen gas. During the reaction, the powder for PI solid phase polymerization and PI, which is a polymerization product, were prevented from being blocked, and the mixture was sufficiently stirred so that heat was transferred uniformly. After completion of the reaction, the pressure is released and cooled, and the powder is further treated at 240 ° C. for 2 hours in a nitrogen gas stream to obtain a non-crystalline PI powder having a volume-based average particle size of 300 μm by laser diffraction. (A-1) was obtained. Nw of A-1 was measured by the above-mentioned method. In addition, the glass transition temperature was measured by DSC. Next, when A-1 was dissolved in NMP, it was found that it was dissolved at a PI concentration of 10% by mass or more. Further, A-1 is dissolved in NMP to prepare an NMP solution having a PI concentration of 15% by mass, and this solution is applied onto a glass plate with a bar coater, and then the NMP is evaporated in a dryer at 200 ° C. , PI coating was prepared. After that, the obtained coating film was peeled off from the glass plate to obtain a PI film having a thickness of 20 μm. Table 1 shows the results of measuring the tensile strength of this film based on JISK-7127. In Table 1, when the tensile strength is 100 N / mm ² or more, it is “◯”, when it is 50 N / mm ² or more and 100 N / mm ² or less, it is “Δ”, and when it is less than 50 N / mm ² , it is “×”. It was written.

[Example 2]
Amorphous PI powder (A-2) having an average particle size of 250 μm was obtained in the same manner as in Example 1 except that 0.3 mol of IPDA and 0.7 mol of BAPP were used as the diamine component. .. A PI film was obtained from this powder in the same manner as in Example 1. The results of these characteristic evaluations are shown in Table 1.

[Example 3]
Amorphous PI powder (A-3) having an average particle size of 180 μm as in Example 1 except that 1.0 mol of PMA was used as the acid component and 1.0 mol of AMC was used as the diamine component. ) Was obtained. A PI film was obtained from this powder in the same manner as in Example 1. The results of these characteristic evaluations are shown in Table 1.

[Example 4]
Amorphous PI powder (A-4) having an average particle size of 230 μm was obtained in the same manner as in Example 1 except that the amount of NMP added was 5% by mass. A PI film was obtained from this powder in the same manner as in Example 1. The results of these characteristic evaluations are shown in Table 1.

[Example 5]
1.0 mol (acid component) of 6-FA dimethyl ester and 1.0 mol (diamine component) of 6F-BAPP were dissolved in DMAc to obtain a salt solution having a solid content concentration of 60% by mass. The coating film obtained by casting this solution onto a glass plate is dried at 100 ° C. to form a solid salt film, which is then peeled off from the glass plate and mechanically pulverized in a mortar to obtain average particles. A powder for PI solid phase polymerization having a diameter of 150 μm was obtained. This powder for PI solid phase polymerization contained 7% by mass of DMAc with respect to the mass of the salt. The obtained PI solid phase polymerization powder is put into an aluminum vat and treated in a nitrogen gas atmosphere at 150 ° C. for 1 hour, 200 ° C. for 1 hour, and 250 ° C. for 1 hour to perform solid phase polymerization. Amorphous PI body powder (A-5) having an average particle size of 190 μm was obtained. A PI film was obtained from this powder in the same manner as in Example 1. The results of these characteristic evaluations are shown in Table 1.

[Example 6]
Amorphous with an average particle size of 65 μm in the same manner as in Example 5 and PI powder Example 1, except that 1.0 mol of H-PMDA was used as the acid component and 1.0 mol of BAPP was used as the diamine component. PI powder (A-6) was obtained. A PI film was obtained from this powder in the same manner as in Example 1. The results of these characteristic evaluations are shown in Table 1.

[Example 7]
Amorphous PI powder (A-7) having an average particle size of 32 μm as in Example 1 except that 1.0 mol of H-PMDA was used as the acid component and 1.0 mol of DADE was used as the diamine component. ) Was obtained. A PI film was obtained from this powder in the same manner as in Example 1. The results of these characteristic evaluations are shown in Table 1.

[Example 8]
A mixture of 1.0 mol of BPA dimethyl ester (acid component) and a mixture of 0.5 mol of DADE and 0.5 mol of PGAE (molecular weight 400) (diamine component) as a diamine component is dissolved in NMP, and the solid content concentration is 60. A mass% salt solution was obtained. The coating film obtained by casting this solution onto a glass plate is dried at 100 ° C. to form a solid salt film, which is then peeled off from the glass plate and mechanically pulverized in a mortar to obtain average particles. A powder for PI solid phase polymerization having a diameter of 150 μm was obtained. This powder for PI solid phase polymerization contained 5% by mass of DMAc with respect to the mass of the salt. The obtained PI solid phase polymerization powder was put into an aluminum vat and treated in a nitrogen gas atmosphere at 150 ° C. for 1 hour and at 200 ° C. for 1 hour to cause a solid phase polymerization reaction. A non-crystalline PI powder (A-8) having an average particle size of 230 μm was obtained. A PI film was obtained from this powder in the same manner as in Example 1. The results of these characteristic evaluations are shown in Table 1.

[Comparative Example 1]
PI powder (B-1) was obtained in the same manner as in Example 1 except that the amount of NMP added was 0.5% by mass. An amorphous PI powder PI film having an average particle size of 260 μm was obtained. A PI film was obtained from this powder in the same manner as in Example 1. Various physical properties were evaluated using this film. The results are shown in Table 1.

[Comparative Example 2]
An attempt was made to obtain PI powder (B-2) in the same manner as in Example 1 except that the NMP was set to 100% by mass, but the salt was dissolved in the NMP to form a solution and used for solid phase polymerization. I couldn't.

[Comparative Example 3]
The PI solid phase polymerization powder obtained in Example 5 was reground by a pulverizer using a high-pressure jet stream to obtain atomized PI solid phase polymerization powder having an average particle size of 0.9 μm. .. By performing solid-phase polymerization in the same manner as in Example 5, a non-crystalline PI powder (B-3) having an average particle size of 3.2 μm was obtained. A PI film was obtained from this powder in the same manner as in Example 1. The results of these characteristic evaluations are shown in Table 1.

[Comparative Example 4]
The atomized PI solid phase polymerization powder obtained in Comparative Example 3 was vacuum dried at 80 ° C. for 2 hours to obtain a re-dried PI solid phase polymerization powder. This powder for PI solid phase polymerization contained 0.8% by mass of DMAc with respect to the mass of the salt. By performing solid-phase polymerization in the same manner as in Example 5, a non-crystalline PI powder (B-4) having an average particle size of 2.2 μm was obtained. A PI film was obtained from this powder in the same manner as in Example 1. The results of these characteristic evaluations are shown in Table 1.

As shown in Examples, the PI powder obtained by the present invention is soluble in an amide-based solvent such as NMP and DMAc, which are general-purpose solvents, and has a high degree of polymerization of Mw of 10,000 or more. A PI film or film having high heat resistance and good mechanical properties can be obtained. Therefore, it can be suitably used for the various uses described above. Further, according to the method for producing a PI powder using the powder for PI solid phase polymerization of the present invention, PI having good solubility can be easily obtained as a powder by a simple process. Since this process does not use a poor solvent for dissolution or reprecipitation, it has excellent environmental compatibility.

Although the PI powder obtained by the present invention is obtained by the solid phase polymerization method, it has good solubility. Further, since it has high heat resistance and excellent mechanical strength, it is used for manufacturing heat-resistant insulating tapes, heat-resistant adhesive tapes, high-density magnetic recording bases, capacitors, films for FPC, and the like. Further, for example, it is used for manufacturing molding materials and molded products such as sliding members filled with fluororesin and graphite, structural members reinforced with glass fiber and carbon fiber, bobbins and sleeves of small coils, and tubes for terminal insulation. .. It is also used in the manufacture of laminated materials such as insulating spacers for power transistors, magnetic head spacers, spacers for power relays, and spacers for transformers. It is also used in the manufacture of enamel coating materials for electric wire / cable insulation coatings, solar cells, low temperature storage tanks, space insulation materials, integrated circuits, slot liners, and the like. It is also used in the production of ultrafiltration membranes, reverse osmosis membranes, and gas separation membranes. It is also used in the production of heat-resistant threads, woven fabrics, non-woven fabrics and the like. Further, since it is less colored and has excellent transparency of visible light, it is also used as an optical waveguide, a liquid crystal substrate, a liquid crystal alignment film, an optical component protective film, and the like. Further, it is also used as a binder for electrodes of lithium secondary batteries and the like.

Claims (1)

It is characterized by solid-phase polymerization of a salt composed of tetracarboxylic acid or tetracarboxylic acid diester and substantially equimolar diamine in the presence of a solvent of 1% by mass or more and 30% by mass or less with respect to the mass of this salt. A method for producing a polyimide powder which is soluble in an amide solvent and has a weight average molecular weight of 10,000 or more by GPC.