JP2011116871A - Method for producing phosphorus-containing polyimide - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a flame-retardant phosphorus-containing polyimide, and to provide a phosphorus-containing polyimide obtained by the method. <P>SOLUTION: A new phosphorus-containing polyimide excellent in flame retardancy is obtained by imidizing a polyamic acid having a benzophenone skeleton in the presence of a phosphorus compound expressed by general formula (1). In the formula, R<SB>1</SB>and R<SB>2</SB>each represents a substituted or unsubstituted phenyl or phenoxy group. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing a flame-retardant phosphorus-containing polyimide and a flame-retardant phosphorus-containing polyimide obtained by this production method.

  Generally, polyimide is excellent in flame retardancy, heat resistance, mechanical properties, electrical properties, etc., so it is widely used as a substrate material for flexible printed wiring boards, protective films for wiring and semiconductor elements, heat resistant adhesives, interlayer insulation materials, etc. in use.

  In recent years, it has been desired to reduce the thickness of polyimide used in electrical / electronic devices and the like in order to meet the needs for reduction in thickness and size of electrical / electronic devices. However, the flame retardancy of polyimide tends to decrease with decreasing polyimide film thickness. In recent years, with higher performance of components and elements used in electronic devices and CPUs, the amount of generated heat has increased remarkably and the average temperature in the devices has also increased, so a more advanced flame retardant technology is desired. ing. On the other hand, in order to impart flame retardancy required for electric and electronic products from the viewpoint of environmental problems, there is a demand for safer means in consideration of safety to the natural environment and the human body.

  As a technique for imparting flame retardancy to polyimide, a method of mixing a metal hydrate such as magnesium hydroxide with siloxane-modified polyimide has been proposed (for example, see Patent Document 1). However, in this method, magnesium hydroxide must be separately subjected to a surface treatment with a phosphoric acid surfactant, and the process becomes complicated. In addition, in this method, a diamine having two or more hydroxyl groups in the molecule is recommended as a diamine component to be used for the base polymer, but such a diamine cannot be said to be easily available.

  Moreover, the method of making a flame retardance express by using the specific polyimide resin containing a silicon unit and the specific epoxy resin containing a phosphorus element is proposed (for example, refer patent document 2). In this method, a phosphorus compound and an epoxy resin are reacted to obtain a target phosphorus-containing epoxy resin, but in order to have a function as an epoxy resin, the reaction is preferably performed so that two epoxy groups remain. The upper limit of the phosphorus content is only 5% by weight. Since the polyimide resin introduced with the silicon unit is flammable, in order to give sufficient flame retardancy to the polyimide resin composition obtained by this method, a lot of epoxy resin with low heat resistance must be mixed. Don't be.

  Furthermore, as a method for imparting flame retardancy to a resin composition, a method of adding a phosphorus compound to the resin composition is known (for example, Non-Patent Document 1). However, in order to express flame retardancy with a conventionally known technique, it is necessary to add a large amount of a phosphorus compound.

JP 2008-63459 A JP 2009-29982 A

Flame retardant technology using non-halogen flame retardant materials (NTS), p. 28 (issued in 2001)

  The present invention provides a method for producing a flame-retardant phosphorus-containing polyimide and a phosphorus-containing polyimide obtained by this production method.

  The present inventors have found that a novel phosphorus-containing polyimide having excellent flame retardancy can be obtained by imidizing a polyamic acid having a benzophenone skeleton in the presence of a phosphorus compound having a specific structure, The present invention has been completed. The phosphorus-containing polyimide obtained by the production method of the present invention exhibits excellent flame retardancy without impairing the properties of conventional polyimide. That is, the present invention provides the following formula (I):

（式中、Ｒ_３は二価の有機基を表す）
で表わされるポリアミド酸を、下記式（１）：

(Wherein R ₃ represents a divalent organic group)
A polyamic acid represented by the following formula (1):

（式中、Ｒ_１及びＲ_２は、同一であっても異なっていてもよく、フェニル基又はフェノキシ基であり、ここでＲ_１とＲ_２のベンゼン環上の水素原子の少なくとも一つが、炭素数１〜６のアルキル基若しくはアルコキシル基で置換されていてもよく、及び／又はＲ_１とＲ_２それぞれのベンゼン環上の炭素原子の一つが、とは互いに単結合で結ばれていてもよい）
で表わされるリン化合物の存在下、イミド化することによる、難燃性に優れた、新規な含リンポリイミドの製造方法、及びこの製造方法によって得られる含リンポリイミドに関する。

(Wherein R ₁ and R ₂ may be the same or different and are a phenyl group or a phenoxy group, wherein at least one of the hydrogen atoms on the benzene ring of R ₁ and R ₂ is carbon May be substituted with an alkyl or alkoxyl group of 1 to 6 and / or one of the carbon atoms on each benzene ring of R ₁ and R ₂ may be bonded to each other by a single bond. )
The present invention relates to a novel method for producing a phosphorus-containing polyimide having excellent flame retardancy by imidization in the presence of a phosphorus compound, and a phosphorus-containing polyimide obtained by this production method.

  The production method of the present invention is excellent in that a phosphorus compound can be introduced into a polyimide skeleton by a simple method of imidizing a polyamic acid having a benzophenone skeleton in the presence of a phosphorus compound. Further, the phosphorus-containing polyimide obtained by this production method is useful as a heat-resistant adhesive having flame retardancy, an insulating material for an electronic circuit board having flame retardancy, and the like.

  Hereinafter, embodiments of the present invention will be described in detail.

  The phosphorus-containing polyimide of the present invention has the following formula (I):

（式中、Ｒ_３は二価の有機基を表す）
で表わされるポリアミド酸を、下記式（１）：

(Wherein R ₃ represents a divalent organic group)
A polyamic acid represented by the following formula (1):

（式中、Ｒ_１及びＲ_２は、同一であっても異なっていてもよく、フェニル基又はフェノキシ基であり、ここでＲ_１とＲ_２のベンゼン環上の水素原子の少なくとも一つが、炭素数１〜６のアルキル基若しくはアルコキシル基で置換されていてもよく、及び／又はＲ_１とＲ_２それぞれのベンゼン環上の炭素原子の一つが、互いに単結合で結ばれていてもよい）
で表わされるリン化合物の存在下、熱的にイミド化することによって製造される。加熱することによって、イミド化すると同時にポリイミド骨格中に式（１）で表わされるリン化合物が導入され、本発明の含リンポリイミドが製造される。よって、本発明の含リンポリイミドは、まず対応するポリアミド酸溶液とリン化合物との混合物を製造する。

(Wherein R ₁ and R ₂ may be the same or different and are a phenyl group or a phenoxy group, wherein at least one of the hydrogen atoms on the benzene ring of R ₁ and R ₂ is carbon (It may be substituted with an alkyl group or an alkoxyl group of 1 to 6 and / or one of carbon atoms on each of the benzene rings of R ₁ and R ₂ may be bonded to each other by a single bond)
It is produced by thermally imidizing in the presence of a phosphorus compound represented by: By heating, the phosphorus compound represented by the formula (1) is introduced into the polyimide skeleton simultaneously with imidization, and the phosphorus-containing polyimide of the present invention is produced. Therefore, the phosphorus-containing polyimide of the present invention first produces a mixture of a corresponding polyamic acid solution and a phosphorus compound.

"Production method of polyamic acid"
The polyamic acid used in the present invention is obtained by reacting a benzophenone tetracarboxylic dianhydride with a diamine component represented by the formula: H ₂ N—R ₃ —NH ₂ . This production method is not particularly limited and may be a known method, and is usually carried out in a solvent at a solute concentration of 5 to 80% by weight, preferably 10 to 50% by weight. After completion of the reaction, the reaction solution can be used as it is as a polyamic acid solution (varnish) in the subsequent imidization reaction. Alternatively, the phosphoric acid-containing polyamic acid solution may be prepared by isolating the polyamic acid from the reaction solution and then re-dissolving it in a suitable solvent.

  The solvent used for producing the polyamic acid is not particularly limited as long as it is an inert solvent for the reaction. For example, N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, Tetramethylurea, tetrahydrofuran and the like can be used alone or in a mixed form. Particularly preferred are N, N-dimethylacetamide and N-methyl-2-pyrrolidone. Further, these solvents may be used by mixing a solvent such as toluene, xylene, ethylbenzene, anisole, chlorobenzene, dichlorobenzene, trichlorobenzene, diglyme and triglyme in an arbitrary ratio. These solvents may also be used in preparing the polyamic acid solution by redissolving the isolated polyamic acid.

  Specific examples of the benzophenone tetracarboxylic dianhydride used here include 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 2,3 ′, 3,4′-benzophenone tetracarboxylic dianhydride. Anhydrous, 2,2 ′, 3,3′-benzophenone tetracarboxylic dianhydride.

The diamine component represented by the formula H ₂ N—R ₃ —NH ₂ used here may be an aromatic diamine, an aliphatic diamine or an alicyclic diamine. Therefore, examples of R ₃ include 6 carbon atoms. A divalent group of -14 monocyclic or condensed polycyclic aromatic compounds (for example, phenylene, indenylene, naphthylene, fluorenylene), a divalent group of an aliphatic compound having 2 to 12 carbon atoms (for example, carbon number) 2 to 12 alkanediyl, alkenylene or alkynylene) or a divalent group of an alicyclic compound having 3 to 10 carbon atoms (for example, cycloalkylene or cycloalkenylene having 3 to 10 carbon atoms), or the same or different The two or more divalent groups which may be present may be directly or a cross-linking member (wherein the cross-linking member means —O—, —CO—, —COO—, —OCO—, —SO _2). Selected from the group consisting of —, —S—, —CH ₂ —, —C (CH ₃ ) ₂ — and —C (CF ₃ ) ₂ — (for example, biphenyl-4, 4′-diyl, diphenyl ether-4,4′-diyl, diphenyl ether-3,4′-diyl, benzophenone-4,4′-diyl). These aromatic diamines, aliphatic diamines or alicyclic diamines have one or more substituents selected from alkyl groups having 1 to 6 carbon atoms, alkenyl groups, alkynyl groups or alkoxyl groups, or halogen atoms. It may be.

  Specific examples of the aromatic diamine component include those having one aromatic group: p-phenylenediamine, m-phenylenediamine, p-aminobenzylamine, m-aminobenzylamine, diaminotoluenes, diaminoxylenes, diamino Those having two aromatic groups such as naphthalenes and diaminoanthracenes: 4,4′-diaminobiphenyl, 3,4′-diaminobiphenyl, 3,3′-diaminobiphenyl, o-tolidine, m-tolidine, o -Dianisidine, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether 4,4'-Diaminodiphenyls Hong, 3,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl ketone, 3,4'-diaminodiphenyl ketone, 3,3'-diaminodiphenyl ketone, 3,4 -Diaminobenzophenone, 2,2-bis (4-aminophenoxy) propane, 2,2-bis (3-aminophenoxy) propane, 2- (3-aminophenyl) -2- (4-aminophenyl) propane, etc. Those having three aromatic groups: 1,4-bis (4-aminophenoxy) benzene, 1,4-bis (3-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1, 3-bis (3-aminophenoxy) benzene, 1,4-bis (4-aminobenzoyl) benzene, 1,4-bis (3-aminobenzene) 4 aromatic groups such as zoyl) benzene, 1,3-bis (4-aminobenzoyl) benzene, 1,3-bis (3-aminobenzoyl) benzene, 9,9-bis (4-aminophenyl) fluorene Those having the above: 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 4,4′-bis (4-aminophenoxy) biphenyl, 4,4′-bis (3-aminophenoxy) biphenyl, Bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] sulfone, bis [4- (4-aminophenoxy) phenyl] ether, bis [4- (3-amino Phenoxy) phenyl] ether, 4,4′-bis (4-aminophenoxy) benzophenone, 4,4′-bis (3-aminophenoxy) benzo Phenone, 1,4-bis [4- (2-, 3- or 4-aminophenoxy) benzoyl] benzene, 1,3-bis [4- (2-, 3- or 4-aminophenoxy) benzoyl] benzene, 1,4-bis [3- (2-, 3- or 4-aminophenoxy) benzoyl] benzene, 1,3-bis [3- (2-, 3- or 4-aminophenoxy) benzoyl] benzene, 4, 4′-bis [4- (2-, 3- or 4-aminophenoxy) benzoyl] diphenyl ether, 4,4′-bis [3- (2-, 3- or 4-aminophenoxy) benzoyl] diphenyl ether, 4, 4′-bis [4- (2-, 3- or 4-aminophenoxy) benzoyl] biphenyl, 4,4′-bis [3- (2-, 3- or 4-aminophen Xyl) benzoyl] biphenyl, 4,4′-bis [4- (2-, 3- or 4-aminophenoxy) benzoyl] diphenylsulfone, 4,4′-bis [3- (2-, 3- or 4- Aminophenoxy) benzoyl] diphenylsulfone and the like. Moreover, the hydrogen atom on these aromatic rings may be substituted with one or more substituents selected from an alkyl group having 1 to 6 carbon atoms, an alkenyl group, an alkynyl group, an alkoxyl group, or a halogen atom. In view of availability, specifically p-phenylenediamine, m-phenylenediamine, 4,4′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 1,4-bis (4-aminophenoxy) Benzene, 1,4-bis (3-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 2,2-bis [4- ( 4-aminophenoxy) phenyl] propane, 4,4′-bis (4-aminophenoxy) biphenyl, 4,4′-bis (3-aminophenoxy) biphenyl, bis [4- (4-aminophenoxy) phenyl] sulfone , Bis [4- (3-aminophenoxy) phenyl] sulfone, 9,9-bis (4-aminophenyl) fluorene Preferred.

  Specific examples of the aliphatic or alicyclic diamine component include 1,2-diaminoethane, 1,2-diaminopropane, 1,3-diaminopropane, 1,4-diaminobutane, 1,3-diaminopentane, , 5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 1,11-diaminoundecane, 1,12 -Diaminododecane, 2-methyl-1,5-diaminopentane, 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, 1,3-diaminocyclohexane, 1,4-diaminocyclohexane 4,4′-diaminodicyclohexylmethane, isophoronediamine and the like. In view of availability, specifically, 1,6-diaminohexane, 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, 1,4-diaminocyclohexane, 4 4,4′-diaminodicyclohexylmethane, isophoronediamine is preferably used.

  You may use the above diamine component individually or in mixture of 2 or more types. Furthermore, the following formula (2)

(In the formula, m is an integer mixed value of 0 to 20, R ₄ represents a methyl, isopropyl, phenyl, or vinyl group, and R ₅ represents a divalent group of a hydrocarbon having 1 to 7 carbon atoms, for example, A siloxane diamine represented by (trimethylene, tetramethylene, phenylene, etc.) may be copolymerized in the range of 1 to 50 mol% of the diamine component.

  The polyamic acid obtained by reacting the benzophenone tetracarboxylic dianhydride of the present invention with the diamine component does not mean only the polyamic acid consisting only of the repeating unit represented by the general formula (I), and such It is meant to include those containing a repeating unit as a main constituent unit. Therefore, in the production of the polyamic acid, the purpose of the phosphorus-containing polyimide of the present invention and the reactivity of the polyamic acid that is the precursor thereof are not affected. Things can be used in part.

  Examples of such tetracarboxylic dianhydrides include pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,3 ′, 3,4′-biphenyltetracarboxylic acid. Acid dianhydride, 2,2 ′, 3,3′-biphenyltetracarboxylic dianhydride, 4,4′-oxydiphthalic dianhydride, 3,4′-oxydiphthalic dianhydride, 3,3′- Oxydiphthalic dianhydride, 4,4′-diphenylsulfonetetracarboxylic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 2,2-bis (3,4-di Carboxyphenyl) hexafluoropropane dianhydride, 1,2,7,8-naphthalene tetracarboxylic dianhydride, and the like. In order to provide a phosphorus-containing polyimide having excellent flame retardancy, which is an object of the present invention, it is necessary to use 30 mol% or more of benzophenone tetracarboxylic dianhydride in the tetracarboxylic dianhydride component to be used. Preferably, it is more preferable to use 50 mol% or more.

  Further, a monoamine compound or a dicarboxylic acid anhydride may be added for the purpose of adjusting the molecular weight. Examples of the monoamine compound used include aniline, 4-aminophenol, 3-aminophenol, 4-aminobiphenyl, 4-phenoxyaniline, 3-aminophenylacetylene, 4-aminophenylacetylene, and the like as dicarboxylic acid anhydrides. Maleic anhydride, phthalic anhydride, 4-phenylethynyl phthalic anhydride, 4-ethynyl phthalic anhydride, trimellitic acid and the like. The amount of monoamine compound or dicarboxylic acid anhydride added varies depending on the molecular weight of the target polyimide, but it is usually 1.0 to several times the mole difference between the number of moles of all acid dianhydrides used and the diamine compound. It is a number, preferably 1.5 to 4.0 times. When there are many acid dianhydrides, a monoamine compound is added, and when there are many diamine compounds, a dicarboxylic acid anhydride is added.

In the phosphorus compound represented by the formula (1), R ₁ and R ₂ are both phenyl groups (wherein at least one hydrogen atom on the benzene ring is an alkyl group or alkoxyl group having 1 to 6 carbon atoms). (Which may be substituted with the above) is preferred, and specific examples thereof include the following formula (1a):

で表わされる９，１０−ジヒドロ−９−オキサ−１０−ホスファフェナントレン−１０−オキシド（ＨＣＡ）が挙げられる。

9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (HCA) represented by the formula:

Similarly, as the phosphorus compound represented by the formula (1), one of R ₁ and R ₂ is a phenyl group, the other is a phenoxy group, and one of the carbon atoms on each benzene ring is mutually simple. Preferred are those bonded by a bond (wherein at least one of the hydrogen atoms on the benzene ring may be substituted with an alkyl group or alkoxyl group having 1 to 6 carbon atoms). Formula (1b):

で表わされるジフェニルホスフィンオキシド（ＤＰＯ）が挙げられる。

The diphenylphosphine oxide (DPO) represented by these is mentioned.

  The amount of the phosphorus compound represented by the formula (1) is 0.5 to several times the number of moles of the benzophenone tetracarboxylic dianhydride used, preferably 0.8 to 4.0 times mole. It is.

"Production method of phosphorus-containing polyimide"
The phosphorus-containing polyimide of the present invention is produced by imidizing the polyamic acid obtained as described above in the presence of the phosphorus compound represented by the formula (1). For example, imidization may be carried out after adding the phosphorus compound represented by the formula (1) to the polyamic acid solution obtained as described above. Alternatively, polyamic acid may be produced as described above from benzophenonetetracarboxylic dianhydride and a diamine component in a solvent to which a phosphorus compound represented by formula (1) has been added in advance, and then imidization may be performed. .

  The phosphorus compound represented by the formula (1) may be added directly to the solution of the polyamic acid or the reaction solvent, but is an inert solvent such as N, N-dimethylformamide, N, N-dimethylacetamide, N -Methyl-2-pyrrolidone, dimethyl sulfoxide, tetramethylurea, tetrahydrofuran, toluene, xylene, ethylbenzene, anisole, chlorobenzene, dichlorobenzene, trichlorobenzene, diglyme, triglyme, etc., 5 to 90% by weight, preferably 10 to 80% You may add, after making it melt | dissolve in the solute concentration of a weight%.

  Subsequently, the mixed solution of the polyamic acid and the phosphorus compound is a glass plate, a metal foil such as copper, aluminum, or stainless steel, or polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyphenylene sulfide (PPS), polyimide, It is applied on a substrate such as a resin film such as a silicon resin or a fluororesin so that the thickness after drying is 0.1 to 250 μm, more preferably 1.0 to 100 μm, and more preferably 40 to 500 ° C. Can be obtained by drying at 70 to 350 ° C. for 1 minute to 5 hours, more preferably 3 minutes to 3 hours. The obtained polyimide can be peeled off from the substrate and used as a film or as a laminate.

  Further, a solvent azeotropic with water, such as toluene, xylene, ethylbenzene, chlorobenzene, dichlorobenzene, and trichlorobenzene, is added to the mixed solution of the polyamic acid and the phosphorus compound, and the temperature is 100 to 300 ° C, more preferably 150 to 250 ° C. It is possible to obtain a phosphorus-containing polyimide by heating with, discharging water generated by imidization out of the system and performing thermal imidization. At this time, a nitrogen-containing heterocyclic compound such as pyridine, picoline or imidazole, or a tri-lower alkylamine such as triethylamine may be used. Alternatively, a dehydrating agent such as acetic anhydride, trifluoroacetic anhydride, N, N-dicyclohexylcarbodiimide and a nitrogen-containing heterocyclic compound such as pyridine, picoline or imidazole, or a tri-lower alkylamine such as triethylamine are added. Phosphorus-containing polyimide can also be obtained by performing chemical imidation by dehydrating at ˜200 ° C. for 1 to 24 hours. The solution that has been imidized thermally or chemically as described above is poured into a single solvent such as water, methanol, ethanol, isopropanol, acetone, toluene, xylene or a mixed solution thereof to precipitate crystals and filter. Separately, it can be dried and pulverized to obtain a powder form. The obtained polyimide can be used for injection molding or compression molding as it is. Separately, it can be dissolved in a solvent and used as a varnish, or it can be applied on the aforementioned substrate and dried to obtain a film form.

  In order to clarify the mode of the present invention, examples and comparative examples are shown below, but the present invention is not limited to the examples shown here.

  The solution viscosity, glass transition temperature, heat distortion temperature and infrared absorption spectrum measurement method and flame retardancy evaluation for the compounds obtained in the examples are as follows.

Solution viscosity: Measured at a temperature of 25 ° C. using a B-type viscometer (manufactured by Tokyo Keiki).

Glass transition temperature: A differential scanning calorimeter (DSC-60, manufactured by Shimadzu Corporation) was heated to 40 to 400 ° C. at 10 ° C. per minute and measured. The glass transition temperature was calculated from the extrapolation point of the DSC curve by analysis software.

Infrared absorption spectrum: Measured by an ATR method using an IR measuring device (Prestage 21 manufactured by Shimadzu Corporation).

Evaluation of flame retardancy: The film was cut into a size of 200 mm × 50 mm to obtain a test piece. The test piece was wound in a cylindrical shape, fixed vertically to the clamp, and subjected to indirect flame twice for 3 seconds with a burner at the bottom of the sample.

Example 1
In a four-necked flask equipped with a thermometer and a nitrogen introduction tube, in a stream of nitrogen, 4,4′-diaminodiphenyl ether (4-ODA) (manufactured by Wakayama Seika Co., Ltd.) 10.118 g (0.05 mol), 9,10 -Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (HCA) (manufactured by Sanko Co., Ltd.) 10.8086 g (0.05 mol), N-methyl-2-pyrrolidone (NMP) 148.0 g, Dissolved. Thereafter, 3,113 ′, 4,4′-benzophenonetetracarboxylic dianhydride (BTDA) (manufactured by Daicel Chemical) was charged with 16.11313 g (0.05 mol) and stirred at room temperature for 12 hours. A mixed solution of polyamic acid and a phosphorus compound having a 000 mPa · s and a solute concentration of 20% was obtained. The obtained mixed solution is coated on a glass plate so that the thickness after drying is 20 μm, dried at 90 ° C., 130 ° C., and 180 ° C. for 30 minutes, and then peeled off from the glass plate to form a metal frame. After fixing, heat treatment was performed at 200 ° C. and 250 ° C. for 1 hour to obtain a polyimide film containing 4.4% (theoretical value) of phosphorus atoms in the repeating unit. When the IR of the polyimide film was measured, the absorption of the carbonyl stretching vibration of benzophenone at 1670 cm ⁻¹ disappeared. The glass transition temperature of the film was 255 ° C., and the flame retardancy evaluation was ○.

Comparative Example 1
In a four-necked flask equipped with a thermometer and a nitrogen introducing tube, in a nitrogen stream, 4,4′-diaminodiphenyl ether (4-ODA) (manufactured by Wakayama Seika Co., Ltd.) 10.118 g (0.05 mol), N-methyl 148.0 g of 2-pyrrolidone (NMP) was charged and dissolved. Subsequently, 3,113 ′, 4,4′-biphenyltetracarboxylic dianhydride (BTDA) (manufactured by Daicel Chemical) was charged with 16.113 g (0.05 mol) and stirred at room temperature for 12 hours. A polyamic acid solution having 500 mPa · s and a solute concentration of 15% was obtained. The obtained polyamic acid solution was coated on a glass plate so that the thickness after drying was 20 μm, dried at 90 ° C., 130 ° C., and 180 ° C. for 30 minutes, and then peeled off from the glass plate. The polyimide film containing no phosphorus was obtained by heat treatment at 200 ° C. and 250 ° C. for 1 hour. The glass transition temperature of the film was 263 ° C., and the flame retardancy evaluation was x.

Comparative Example 2
In a four-necked flask equipped with a thermometer and a nitrogen inlet tube, in a nitrogen stream, 4,118 ′ (0.05 mol) of 4,4′-diaminodiphenyl ether (4-ODA), 9,10-dihydro-9-oxa- 21.6172 g (0.10 mol) of 10-phosphaphenanthrene-10-oxide (HCA) (manufactured by Sanko Co., Ltd.) and 188.6 g of N-methyl-2-pyrrolidone (NMP) were charged and dissolved. Thereafter, 15.5107 g (0.05 mol) (manac Co., Ltd.) of 4,4′-oxydiphthalic dianhydride was charged, and the mixture was stirred at room temperature for 12 hours to give a polyamide having a solution viscosity of 7,800 mPa · s and a solute concentration of 20%. A mixture of an acid solution and a phosphorus compound was obtained. The obtained mixture is applied onto a glass plate so that the thickness after drying is 20 μm, dried at 90 ° C., 130 ° C., and 180 ° C. for 30 minutes, and then peeled off from the glass plate and fixed to a metal frame. Then, heat treatment was performed at 200 ° C. and 250 ° C. for 1 hour to obtain a polyimide film. The presence of phosphorus was not observed when the IR of the polyimide film was measured. The glass transition temperature of the film was 228 ° C., and the flame retardancy evaluation was x.

Examples 2 to 4, Comparative Example 3
In the same manner as in Example 1, various components were changed to prepare a polyimide film. The composition and results are shown in Table 1.

The abbreviations in the table indicate the following.
BTDA: 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride DSDA: 3,3 ′, 4,4′-diphenylsulfone tetracarboxylic dianhydride APB: 1,3-bis (3-amino Phenoxy) benzene BAPP: 2,2-bis [4- (4-aminophenoxy) phenyl] propane BAPS: bis [4- (4-aminophenoxy) phenyl] sulfone HCA: 9,10-dihydro-9-oxa-10 -Phosphaphenanthrene-10-oxide DPO: Diphenylphosphine oxide (Aldrich)

By using the production method of the present invention, the phosphorus-containing polyimide can be produced by a simple method without requiring a special apparatus or process. In addition, the phosphorus-containing polyimide produced by using this production method is very useful as a heat-resistant adhesive, an insulating material for an electronic circuit board, and the like that are required to be thinned and flame-retardant.

Claims (5)

Polyamic acid obtained by reacting benzophenonetetracarboxylic dianhydride and diamine is represented by the following general formula (1)

Wherein R ₁ and R ₂ may be the same or different and are phenyl or phenoxy groups;
Here, at least one hydrogen atom on the benzene ring of R ₁ and R ₂ may be substituted with an alkyl group or alkoxyl group having 1 to 6 carbon atoms, and / or benzene of each of R ₁ and R ₂ One of the carbon atoms on the ring may be connected to each other by a single bond)
A method for producing a phosphorus-containing polyimide, wherein imidization is performed in the presence of a phosphorus compound represented by the formula: In the phosphorus compound of the general formula (1), R ₁ and R ₂ are both phenyl groups, or _one of R ₁ and R ₂ is a phenyl group and the other is a phenoxy group, and each benzene One of the carbon atoms on the ring is bonded to each other by a single bond (wherein at least one of the hydrogen atoms on the benzene ring may be substituted with an alkyl group or alkoxyl group having 1 to 6 carbon atoms). The method for producing a phosphorus-containing polyimide according to claim 1. The phosphorus compound described in the general formula (1) is represented by the following formula (1a)

And / or the following formula (1b)

The method for producing a phosphorus-containing polyimide according to claim 1 or 2. The benzophenone tetracarboxylic dianhydride is 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 2,3 ′, 3,4′-benzophenone tetracarboxylic dianhydride, and 2,2 The manufacturing method as described in any one of Claims 1-3 which is 1 type, or 2 or more types of compounds chosen from the group which consists of ', 3,3'- benzophenone tetracarboxylic dianhydride. The phosphorus-containing polyimide obtained by the manufacturing method as described in any one of Claims 1-4.