JP3386856B2 - Method for producing powdery polyimide precursor - Google Patents
Method for producing powdery polyimide precursorInfo
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- JP3386856B2 JP3386856B2 JP20276493A JP20276493A JP3386856B2 JP 3386856 B2 JP3386856 B2 JP 3386856B2 JP 20276493 A JP20276493 A JP 20276493A JP 20276493 A JP20276493 A JP 20276493A JP 3386856 B2 JP3386856 B2 JP 3386856B2
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- polyimide precursor
- polyimide
- powder
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- present
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Description
【発明の詳細な説明】
【0001】
【産業上の利用分野】本発明は、ポリイミド前駆体粉粒
体の製造方法に関するものである。
【0002】
【従来の技術】従来、代表的なポリイミド前駆体である
ポリアミド酸は、N,N−ジメチルホルムアミド、N−
メチル−2−ピロリドン、ヘキサメチルホスホルアミ
ド、N−メチルカプロラクタム、ジメチルスルホキシ
ド、N−アセチル−2−ピロリドン、N,N−ジメチル
アセトアミド等ポリアミド酸と強く溶媒和する、いわゆ
る非プロトン系極性溶媒中で低温溶液重合方法で製造さ
れてきた。
【0003】特公昭39−22196号公報、特公昭3
9−30060号公報、特開昭60−221425号公
報、特開昭61−234号公報、特開昭61−2500
30号公報、特開平2−18420号公報には、ポリイ
ミド前駆体の非プロトン系極性溶媒溶液にアセトン、酢
酸エチルのような貧溶媒と無水酢酸、ピリジンのような
閉環剤を加え、ポリイミド粉粒体を得る方法や、ポリイ
ミド前駆体の非プロトン系極性溶媒溶液とアセトンやハ
ロゲン化炭化水素とを混合しポリイミド前駆体の粉粒体
を得る方法が開示されている。しかし、これらの製造方
法においては、溶媒の除去が難しく、また、得られるポ
リイミド粉粒体やポリイミド前駆体の粉粒体からは、特
別な成形法を用いなければ良好な成形体を得ることがで
きない等という問題点を有していた。
【0004】また、これら問題点を解決する方法とし
て、テトラヒドロフランのような低沸点で溶媒除去が容
易な溶媒を使用して重合反応を行い、ポリイミド前駆体
粉粒体を生成せしめる方法が知られている(工業化学雑
誌,71巻,9号,1559〜1564頁,1968年,J.Appl.Polym
er Sci.,vol.11,609〜627,1967年)。この方法によれ
ば、確かに、ポリイミド前駆体と強く溶媒和するような
非プロトン系極性溶媒を含有しないポリイミド前駆体粉
粒体が得られるが、その重合度は低く、高々0.5〜
0.6程度の固有粘度のものしか得られず、そのポリイ
ミド成形体は充分な力学的特性が得られないという問題
点があった。
【0005】
【発明が解決しようとする課題】そこで、本発明の課題
は、溶媒除去が容易で、重合度の高いポリイミド前駆体
の粉粒体が容易に製造できるポリイミド前駆体の粉粒体
の製造方法を提供することにある。
【0006】
【課題を解決するための手段】本発明者らは、上記課題
を解決すべく鋭意検討した結果、水溶性ケトン類中でテ
トラカルボン酸二無水物とジアミンを重合すると、溶媒
との相互作用が少なく、また、その高い蒸気圧とも相ま
って溶媒除去が容易であり、固有粘度が0.7以上のポ
リイミド前駆体の粉粒体が得られ、このポリイミド前駆
体の粉粒体は成形性に優れており、力学的特性が優れ、
残留溶媒が皆無である成形体が得られるという知見を
得、かかる知見に基づいて本発明に到達した。
【0007】すなわち、本発明の要旨は、水溶性ケトン
類中でテトラカルボン酸二無水物およびジアミンを重合
することを特徴とするポリイミド前駆体粉粒体の製造方
法である。
【0008】以下本発明について詳細に説明する。本発
明において、ポリイミド前駆体とは、加熱又は化学作用
により閉環してポリイミドとなり、ポリマー鎖の繰り返
し単位の60モル%以上、好ましくは70モル%以上、
より好ましくは80モル%以上がポリイミド構造となる
有機ポリマーをいい、閉環して非熱可塑性のポリイミド
となるものであればいかなるものでもよい。閉環させる
方法としては、加熱による方法、無水酢酸やピリジンの
ような閉環剤を用いる方法等、従来知られている方法が
適用できる。
【0009】本発明において、好ましいポリイミド前駆
体としては全芳香族系のポリイミド前駆体が挙げられ、
特に一般式(1)で表される繰り返し単位を有する芳香
族ポリアミド酸のホモポリマーまたはコポリマーが好ま
しい。
【0010】
【化1】
【0011】ここで、Rは少なくとも1つの炭素6員環
を含む4価の芳香族残基を示し、4価のうちの2価ずつ
は対をなし、炭素6員環内の隣接する炭素原子に結合し
ている。Rの具体例としては次のようなものが挙げられ
る。
【0012】
【化2】
【0013】特に、Rとしては次のものが好ましい。
【0014】
【化3】
【0015】また、R’は1〜4個の炭素6員環を持つ
2価の芳香族残基を示す。R’の具体例としては次のよ
うなものが挙げられる。
【0016】
【化4】
【0017】
【化5】【0018】また、特にR’としては、次のものが好ま
しい。
【0019】
【化6】
【0020】本発明の製造方法によれば、固有粘度
〔η〕が0.5以上のものが得られるが、目的とする成
形体の強度や弾性率等の特性が良好なものを得るために
は0.7以上とするのが好ましい。〔η〕の値が大きい
ほど、閉環したときに強度や弾性率等の特性が良好なも
のが得られやすい。なお、〔η〕は重合体の分子量と直
接関係する値であり、N,N−ジメチルアセトアミド溶
媒中でポリイミド前駆体濃度0.5重量%、30℃で測
定する。〔η〕を計算するには重合体溶液が標準粘度計
の一定容積の毛細管を流れる時間と溶媒のみが流れる時
間を測定することにより、次式を使用して計算すること
ができる。ここで、cはポリイミド前駆体濃度である。
【0021】
【数1】
【0022】本発明においては、水溶性ケトン類にテト
ラカルボン酸二無水物を溶解あるいは懸濁させておき、
ジアミンを加えて重合させてポリイミド前駆体を製造す
る。水溶性ケトン類の中で好ましい溶媒としては、例え
ば、アセトン、メチルエチルケトン等があげられ、好ま
しくはアセトンである。また、本発明の効果を損なわな
い範囲で他の溶媒を混合することができる。
【0023】反応温度は、−20〜50℃、特に0〜2
0℃が好ましい。また、公知のようにテトラカルボン酸
二無水物とジアミンの仕込比は生成するポリイミド前駆
体の重合度に相関しており、高重合度のポリイミド前駆
体を得るには当モル近傍に仕込むことが好ましい。生成
するポリイミド前駆体は、用いた溶媒には溶解せずに、
溶媒中に懸濁状態になっているので、濾過・乾燥などの
通常の方法によって溶媒を除去してポリイミド前駆体の
粉粒体を得る。この際、ポリイミド前駆体と強く相互作
用しない溶媒を用いているので、溶媒除去が容易であ
り、通常の乾燥方法でも溶媒を含有しないポリイミド前
駆体の粉粒体が得られる。
【0024】また、このとき、溶媒を除去しきらずに、
あるいはポリイミド前駆体の粉粒体を再度溶媒と混合
し、この状態のままで保存することによりポリイミド前
駆体の経時安定性が保たれる。すなわち、ポリイミド前
駆体の粉粒体と、水溶性ケトン類とよりなる懸濁液では
ポリイミド前駆体の粉粒体の経時安定性が保たれる。
【0025】ポリイミド前駆体の粉粒体は、球状、不定
形状、繊維状などのいかなる形状にしてもよい。その粒
径は100μm以下のものを80重量%以上含むものに
することが好ましい。
【0026】ポリイミド前駆体の粉粒体は、公知の方法
によって成形体にすることができる。例えば、加熱、加
圧して閉環させるとともに粉粒体を合着・成形させるこ
とにより、また、加熱・加圧して合着させる前に、ポリ
イミド前駆体の繰り返し構成単位の一部を閉環してポリ
イミドに変換させた後、加熱、加圧して成形することが
できる。前者の場合は、20〜300℃、500〜50
00kg/cm2 で成形した後、300〜400℃で真
空中もしくは窒素中で焼結して、また、後者の場合は、
ポリイミド前駆体の粉粒体を150〜200℃において
3〜10時間かけてポリイミドに変換した後、250〜
300℃、500〜3000kg/cm2 でプレス成形
をして成形体を得る。ここで、ポリイミド前駆体を閉環
させる際、温度を制御することにより、閉環剤の添加量
を制御することによりポリイミドへの変換率を制御する
ことができる。
【0027】
【実施例】以下、実施例により本発明を具体的に説明す
る。なお、実施例において測定方法は、次に述べるとお
りである。
【0028】(1)粉粒体の粒度:レーザー回折/散乱
式粒度分布測定(堀場製作所製LA−500)にて測定
した。
【0029】(2)イミド化率:赤外吸収スペクトルの
604cm-1と880cm-1の吸光度比(吸光度0.8
04でイミド化率100%とした)から求めた。
【0030】(3)表面積:BET吸着法により窒素吸
着量から得られたポリイミド粉粒体グラム当りの平方メ
ートル数である。
【0031】(4)強度:ポリイミド粉粒体を成形し
て、曲げ試験(JIS−K7203)にて評価した。
【0032】実施例1
3.46gのピロメリット酸二無水物(PMDA)に、
79gのアセトンに溶解したジアミノジフェニルエーテ
ル(DADE)3.16gを1時間かけて25℃で滴下
し、攪拌を続けた。滴下終了後、さらに1時間攪拌を続
け、白黄色の懸濁液を得た。この懸濁液を減圧下で濾別
し、表1に示す特性の白黄色のポリイミド前駆体の粉粒
体を得た。さらに、これを、減圧下60℃で1時間乾燥
した後、180℃で10時間かけてイミド化を行いポリ
イミド粉粒体を得た(イミド化率=74%)。さらに、
得られたポリイミド粉粒体を38メッシュの篩上で粉砕
し、極小量含まれる不良粒子を取り除いた後、曲げ試験
片作成用の金型に充填し、300℃に熱したプレス板上
で1000kg/cm2 の圧力で30分間圧縮成形し、
曲げ試験片を作成し、曲げ試験を行った。その結果を表
1に示す。
【0033】実施例2
2.19gのPMDAと2.00gのDADEに50g
のアセトンを加え、25℃で攪拌を続けた。30分程で
懸濁状となり、さらに、1時間攪拌を続け懸濁液を得
た。この懸濁液を減圧下で濾別し、表1に示す特性の白
黄色のポリイミド前駆体の粉粒体を得た。さらに、実施
例1同様にして、ポリイミド粉粒体を得た(イミド化率
=72%)。得られたポリイミド粉粒体を実施例1と同
様にして、曲げ試験を行った。その結果を表1に示す。
【0034】実施例3
95gのアセトンを5℃に冷却し、これに4.41gの
PMDAを溶解させた後、4.03gのDADEを一度
に加え、5℃で1時間攪拌を続けた。冷却をやめ、さら
に6時間攪拌し、懸濁液を得た。この懸濁液を減圧下で
濾別し、表1に示す特性の白黄色のポリイミド前駆体の
粉粒体を得た。さらに、実施例1と同様にしてポリイミ
ド粉粒体(イミド化率=75%)を得た。得られたポリ
イミド粉粒体を実施例1同様にして、曲げ試験を行っ
た。その結果を表1に示す。
【0035】
【表1】
【0036】
【発明の効果】本発明の製造方法によれば、溶媒除去が
容易で、重合度の高いポリイミド前駆体の粉粒体が容易
に製造できる。また、本発明によって得られたポリイミ
ド前駆体の粉粒体から得られるポリイミド成形体は、力
学的特性が優れ、残留溶媒が少ない。Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyimide precursor powder. [0002] Conventionally, polyamic acids which are typical polyimide precursors include N, N-dimethylformamide and N-N-dimethylformamide.
In a so-called aprotic polar solvent which strongly solvates with polyamic acids such as methyl-2-pyrrolidone, hexamethylphosphoramide, N-methylcaprolactam, dimethylsulfoxide, N-acetyl-2-pyrrolidone, N, N-dimethylacetamide And produced by a low-temperature solution polymerization method. [0003] Japanese Patent Publication No. 39-22196, Japanese Patent Publication No. 3
JP-A-9-30060, JP-A-60-221425, JP-A-61-234, JP-A-61-2500
No. 30, JP-A-2-18420, a poor solvent such as acetone and ethyl acetate and a ring-closing agent such as acetic anhydride and pyridine are added to an aprotic polar solvent solution of a polyimide precursor. Disclosed are a method of obtaining a polyimide precursor, and a method of mixing a solution of a polyimide precursor in an aprotic polar solvent with acetone or a halogenated hydrocarbon to obtain a powder of a polyimide precursor. However, in these production methods, it is difficult to remove the solvent, and from the obtained polyimide powder or polyimide precursor powder, a good molded product can be obtained unless a special molding method is used. There was a problem that it was not possible. As a method for solving these problems, there is known a method in which a polymerization reaction is carried out using a solvent having a low boiling point and easy to remove the solvent, such as tetrahydrofuran, to produce polyimide precursor particles. (Industrial Chemistry Magazine, Vol. 71, No. 9, pp. 1559-1564, 1968, J. Appl. Polym
er Sci., vol. 11, 609-627, 1967). According to this method, it is possible to obtain a polyimide precursor powder that does not contain an aprotic polar solvent that is strongly solvated with the polyimide precursor, but the degree of polymerization is low, and at most 0.5 to
There was a problem that only a material having an intrinsic viscosity of about 0.6 was obtained, and the polyimide molded product could not obtain sufficient mechanical properties. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a polyimide precursor powder / granule which can easily remove a solvent and has a high degree of polymerization. It is to provide a manufacturing method. Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that polymerization of tetracarboxylic dianhydride and diamine in water-soluble ketones leads to The interaction is small, and the solvent removal is easy due to the high vapor pressure, and a powder of a polyimide precursor having an intrinsic viscosity of 0.7 or more is obtained. Excellent in mechanical properties
The inventors have found that a molded article having no residual solvent can be obtained, and have reached the present invention based on the finding. That is, the gist of the present invention is a method for producing a polyimide precursor powder, characterized by polymerizing tetracarboxylic dianhydride and diamine in a water-soluble ketone. Hereinafter, the present invention will be described in detail. In the present invention, the polyimide precursor is a polyimide that is closed by heating or a chemical action to form a polyimide, and 60 mol% or more, preferably 70 mol% or more of the repeating unit of the polymer chain,
More preferably, it refers to an organic polymer in which at least 80 mol% has a polyimide structure, and any polymer may be used as long as it is closed to form a non-thermoplastic polyimide. As a method for ring closure, a conventionally known method such as a method by heating, a method using a ring closing agent such as acetic anhydride or pyridine, or the like can be applied. In the present invention, preferred polyimide precursors include wholly aromatic polyimide precursors,
Particularly, an aromatic polyamic acid homopolymer or copolymer having a repeating unit represented by the general formula (1) is preferable. [0010] Here, R represents a tetravalent aromatic residue containing at least one six-membered carbon ring, and two of the four valences form a pair, and adjacent carbon atoms in the six-membered carbon ring Is bound to. Specific examples of R include the following. Embedded image Particularly, R is preferably the following. Embedded image R 'represents a divalent aromatic residue having 1 to 4 carbon 6-membered rings. Specific examples of R ′ include the following. Embedded image Embedded image The following are particularly preferred as R '. Embedded image According to the production method of the present invention, a product having an intrinsic viscosity [η] of 0.5 or more can be obtained. Is preferably 0.7 or more. The larger the value of [η], the easier it is to obtain a material having good properties such as strength and elastic modulus when the ring is closed. [Η] is a value directly related to the molecular weight of the polymer, and is measured at 30 ° C. in a N, N-dimethylacetamide solvent at a polyimide precursor concentration of 0.5% by weight. [Η] can be calculated by measuring the time during which the polymer solution flows through a fixed volume capillary of a standard viscometer and the time during which only the solvent flows, using the following equation. Here, c is the polyimide precursor concentration. [Equation 1] In the present invention, tetracarboxylic dianhydride is dissolved or suspended in a water-soluble ketone,
Diamine is added and polymerized to produce a polyimide precursor. Preferred solvents among the water-soluble ketones include, for example, acetone, methyl ethyl ketone and the like, and acetone is preferred. Further, other solvents can be mixed as long as the effects of the present invention are not impaired. The reaction temperature is -20 to 50 ° C, especially 0 to 2 ° C.
0 ° C. is preferred. In addition, as is known, the charging ratio of tetracarboxylic dianhydride and diamine is correlated with the degree of polymerization of the resulting polyimide precursor, and to obtain a polyimide precursor having a high degree of polymerization, it is necessary to charge the precursor in the vicinity of equimolar. preferable. The generated polyimide precursor is not dissolved in the solvent used,
Since it is suspended in the solvent, the solvent is removed by a usual method such as filtration and drying to obtain a polyimide precursor powder. In this case, since a solvent that does not strongly interact with the polyimide precursor is used, the solvent can be easily removed, and powdery polyimide precursor particles containing no solvent can be obtained even by a normal drying method. At this time, without removing the solvent,
Alternatively, the polyimide precursor particles are mixed again with a solvent and stored in this state, whereby the stability of the polyimide precursor over time is maintained. That is, the suspension of the polyimide precursor powder and the water-soluble ketones maintains the stability of the polyimide precursor powder over time. The powder of the polyimide precursor may have any shape such as a spherical shape, an irregular shape, or a fibrous shape. It is preferable that the particles have a particle size of not more than 100 μm and not less than 80% by weight. The powder of the polyimide precursor can be formed into a molded product by a known method. For example, by heating and pressurizing to close the ring and coalescing and molding the powder and granular material, and before heating and pressurizing to coalesce, a part of the repeating structural units of the polyimide precursor is closed to form a polyimide. , And then heated and pressed for molding. In the former case, 20-300 ° C, 500-50
After molding at 00 kg / cm 2 , sintering in vacuum or nitrogen at 300 to 400 ° C., and in the latter case,
After converting the polyimide precursor powder to polyimide at 150 to 200 ° C. over 3 to 10 hours, 250 to
Press molding is performed at 300 ° C. and 500 to 3000 kg / cm 2 to obtain a molded body. Here, when the polyimide precursor is ring-closed, the conversion rate to polyimide can be controlled by controlling the temperature and controlling the amount of the ring-closing agent to be added. The present invention will be described below in detail with reference to examples. In addition, the measuring method in an Example is as follows. (1) Particle size of powder: Measured by laser diffraction / scattering type particle size distribution measurement (LA-500, manufactured by Horiba, Ltd.). (2) Imidation ratio: Absorbance ratio between 604 cm -1 and 880 cm -1 in the infrared absorption spectrum (absorbance 0.8
04 and the imidation ratio was 100%). (3) Surface area: the number of square meters per gram of polyimide powder obtained from the nitrogen adsorption amount by the BET adsorption method. (4) Strength: A polyimide powder was molded and evaluated by a bending test (JIS-K7203). Example 1 To 3.46 g of pyromellitic dianhydride (PMDA) was added
3.16 g of diaminodiphenyl ether (DADE) dissolved in 79 g of acetone was added dropwise at 25 ° C. over 1 hour, and stirring was continued. After completion of the dropwise addition, stirring was further continued for 1 hour to obtain a white-yellow suspension. This suspension was separated by filtration under reduced pressure to obtain a white and yellow polyimide precursor powder having the characteristics shown in Table 1. Furthermore, this was dried at 60 ° C. for 1 hour under reduced pressure, and then imidized at 180 ° C. for 10 hours to obtain a polyimide powder (imidation ratio = 74%). further,
The obtained polyimide powder is pulverized on a 38-mesh sieve to remove defective particles contained in an extremely small amount, and then filled in a mold for forming a bending test piece, and then 1000 kg on a press plate heated to 300 ° C. Compression molding at a pressure of / cm 2 for 30 minutes,
A bending test piece was prepared and a bending test was performed. Table 1 shows the results. Example 2 2.19g PMDA and 2.00g DADE 50g
Of acetone and stirring was continued at 25 ° C. The suspension became a suspension in about 30 minutes, and stirring was further continued for 1 hour to obtain a suspension. This suspension was separated by filtration under reduced pressure to obtain a white and yellow polyimide precursor powder having the characteristics shown in Table 1. Further, a polyimide powder was obtained in the same manner as in Example 1 (imidization rate = 72%). A bending test was performed on the obtained polyimide powder in the same manner as in Example 1. Table 1 shows the results. Example 3 95 g of acetone was cooled to 5 ° C., 4.41 g of PMDA was dissolved therein, 4.03 g of DADE was added at a time, and stirring was continued at 5 ° C. for 1 hour. The cooling was stopped, and the mixture was further stirred for 6 hours to obtain a suspension. This suspension was separated by filtration under reduced pressure to obtain a white and yellow polyimide precursor powder having the characteristics shown in Table 1. Furthermore, a polyimide powder (imidization rate = 75%) was obtained in the same manner as in Example 1. A bending test was performed on the obtained polyimide powder in the same manner as in Example 1. Table 1 shows the results. [Table 1] According to the production method of the present invention, the solvent can be easily removed and powdery polyimide precursor particles having a high degree of polymerization can be easily produced. In addition, a polyimide molded article obtained from the polyimide precursor powder obtained by the present invention has excellent mechanical properties and has little residual solvent.
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 平6−87958(JP,A) 特開 平6−107819(JP,A) 特開 平6−192420(JP,A) 特開 平6−322123(JP,A) 特開 平7−3019(JP,A) (58)調査した分野(Int.Cl.7,DB名) C08G 73/00 - 73/26 ────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-87958 (JP, A) JP-A-6-107819 (JP, A) JP-A-6-192420 (JP, A) JP-A-6-192420 322123 (JP, A) JP-A-7-3019 (JP, A) (58) Fields investigated (Int. Cl. 7 , DB name) C08G 73/00-73/26
Claims (1)
無水物およびジアミンを重合することを特徴とするポリ
イミド前駆体粉粒体の製造方法。(57) [Claim 1] A method for producing a polyimide precursor powder characterized by polymerizing tetracarboxylic dianhydride and diamine in a water-soluble ketone.
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JP4461606B2 (en) | 2000-10-31 | 2010-05-12 | 宇部興産株式会社 | Polyimide powder manufacturing method, polyimide powder, polyimide powder molded body and manufacturing method thereof |
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