JP2004149990A - Para-oriented aromatic polyamide pulp and para-oriented aromatic polyamide fiber paper containing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a para-oriented aromatic polyamide pulp that can produce paper having high binding performance without damage to the excellent properties of para-oriented aromatic polyamide, e.g., high strength, high heat resistance and high-temperature dimensional stability. <P>SOLUTION: The pulp is produced from para-oriented aromatic polyamide in which the whole length of the pulp is 0.5-5 mm, the freeness is 10 < F ≤ 500 ml according to JIS P 8121 (Canada standard) and L/I is ≤40, measured according to the method described below. <P>COPYRIGHT: (C)2004,JPO

Description

【００１９】
ここでＡｒ_１、Ａｒ_２は芳香族基を表し、その５０モル％以上が下記式（２）から選ばれた同一の、または、相異なるパラ配位の芳香族基からなるものが好ましい。但し、芳香族基の水素原子は、ハロゲン原子、低級アルキル基、フェニル基などで置換されていてもよい。
【００２０】
【化２】

【００２１】
このような芳香族ポリアミド繊維の製造方法や繊維特性については、例えば、英国特許第１５０１９４８号公報、米国特許第３７３３９６４号明細書、第３７６７７５６号明細書、第３８６９４２９号明細書、日本国特許の特開昭４９−１００３２２号公報、特開昭４７−１０８６３号公報、特開昭５８−１４４１５２号公報、特開平４−６５５１３号公報などに記載されており、特に耐熱性の優れたものであるパラ型芳香族ポリアミドの具体例としては、ポリパラフェニレンテレフタルアミド繊維（デュポン（株）製「ケブラー」、テイジントワロン（株）製「トワロン」）や、コポリパラフェニレン・３，４’−オキシジフェニレン・テレフタルアミド繊維（帝人（株）製「テクノーラ」）等が例示される。
【００２２】
本発明のパラ型芳香族ポリアミドパルプは、上記のパラ型芳香族ポリアミドからなり、その繊維長は０．５ｍｍ〜５ｍｍ、好ましくは０．６ｍｍ〜３ｍｍである。該繊維長が０．５ｍｍ未満の場合は、抄紙する際に、パルプの脱落が大きくなる。一方、該繊維長が５ｍｍを超えると抄紙時の分散性、地合が悪くなる。
【００２３】
また、本発明のパラ型芳香族ポリアミドパルプは、その濾水度が１０を超え５００ｍｌ以下であることが必要である。該濾水度が１０ｍｌ以下の場合は、パルプ同士の絡み合いが大きくなりすぎて抄紙時の分散性が不良となり、繊維密度分布の均一性を悪化させる。一方、該濾水度が５００ｍｌを超える場合は、フィブリレーションが小さく、かつフィブリルの短いパルプしか得られないので、紙にしたときに繊維間の交絡が少なく、結果、十分に強力を持たせることができなくなる。
【００２４】
さらに、本発明のパラ型芳香族ポリアミドパルプは、下記方法で測定したＬ／ｌが４０以下であることが肝要である。
【００２５】
ここで、Ｌ／ｌの測定方法としては、パルプ繊維と水を混合して固形分濃度を０．２％としたスラリーから、パルプ繊維を任意に１０本取り出し、それぞれについて、各パルプの全体が視野に収まる倍率で光学顕微鏡写真を撮影し、パルプを構成する主幹の最大幅Ｌと、そこから派生した、最も太い枝の最大幅ｌからＬ／ｌを算出し、１０本の平均値を求める。
【００２６】
このようなＬ／ｌの値を持つパルプを製造する方法としては、例えば、所定の長さに切断したパラ型芳香族ポリアミドからなる短繊維を水と混合し、固形分で２％以上となるようなスラリーを作成して、０．０３ｍｍ以下のクリアランスを空けて回転する２つのディスク間を数回通して叩解させたり、あるいはボールミル等の粉砕機を用いて機械的な剪断力を与えた後に叩解させることによって製造することができる。
【００２７】
また、上記パラ型芳香族ポリアミドパルプを用いて、パラ型芳香族ポリアミド短繊維からなる混抄紙を製造する場合は、パラ型芳香族ポリアミド短繊維が紙の全重量の３０〜９０％、好ましくは４０〜８５％となるようにするのが良い。
【００２８】
この際、使用するパラ型芳香族ポリアミド短繊維の単繊維繊度は、０．１１〜５．５６ｄｔｅｘ（０．１〜５．０ｄｅ）であることが好ましい。該単繊維繊度が０．１１ｄｔｅｘ未満では、製糸技術上困難な点が多く、断糸や毛羽が発生して良好な品質の繊維を安定して生産することが困難になる場合がある上、コストも高くなることがあるため好ましくない。一方、該単繊維繊度が５．５６ｄｔｅｘを超えると繊維間の交絡が少なくなり、強度低下が大きくなる場合があるので好ましくない。
【００２９】
かかる芳香族ポリアミド短繊維の繊維長は、１〜６０ｍｍの範囲のものが好ましく用いられるが、特に、湿式法で紙を形成する場合においては、２〜１２ｍｍの範囲内にあるものが最適である。該繊維長が１ｍｍ未満では、得られる芳香族ポリアミド繊維紙（繊維集合体）の機械的物性が不十分なものとなりことがあり好ましくない。一方、該繊維長が６０ｍｍを超えると、抄紙時に短繊維の分散性等が悪化して得られる繊維集合体の均一性が損なわれ、やはり機械的物性が不十分なものとなることがある。
【００３０】
なお、上記パラ型芳香族ポリアミドパルプが本来有する特性を阻害しない範囲内で、パラ型芳香族ポリアミドパルプ以外のバインダー成分、例えば、メタ型芳香族ポリアミドからなるフィブリッドあるいは未延伸繊維、全芳香族ポリエステルパルプ、有機系樹脂バインダーなどを加えてもよい。この場合、全バインダー成分中に占めるパラ型芳香族ポリアミドパルプの割合は、７０重量％以上、好ましくは８０重量％以上、より好ましくは９０重量％以上である。
【００３１】
上記の如く、パラ型芳香族ポリアミドパルプを用いて、パラ型芳香族ポリアミド短繊維からなる混抄紙を製造する場合は、従来公知の方法により製造することができる。例えば、上記パラ型芳香族ポリアミド短繊維と上記パラ型芳香族ポリアミドパルプとを所定の比率になるように秤量し、繊維濃度が約０．１５〜０．４０重量％となる様に水中に投入して均一分散させた水性スラリー中に、必要に応じて、分散剤や粘度調製剤を加えた後、長網式や丸網式等の抄紙機による湿式抄造法で湿紙を形成し、この湿紙にもし必要ならば、有機系のバインダー樹脂をスプレー方式等により所定の固形分比率になるよう付与した後、乾燥、加熱加圧加工してパラ型芳香族ポリアミド繊維紙を得ることができる。
【００３２】
例えば、カレンダー機を用いて加熱加圧加工を行う場合は、直径約１５〜８０ｃｍからなる１ケの硬質表面ロールと直径約３０〜１００ｃｍからなる１ケの表面変形可能な弾性ロールとの間で、または、より好ましくは、直径約２０〜８０ｃｍからなる２ケの硬質表面ロール同士の間で加熱加圧を行えばよい。
【００３３】
その際、パラ型芳香族ポリアミドパルプのバインダー性能を充分に発揮させるためには、２２０〜４００℃の温度範囲で加熱加圧を行うのがよく、好ましくは、２５０〜３５０℃、さらに好ましくは、２８０℃〜３３０℃の温度範囲で行うことにより優れた結合結果が得られる。
【００３４】
また、加圧の圧力は１４７０〜２４５０Ｎ／ｃｍ（１５０〜２５０ｋｇ／ｃｍ）の範囲の線圧力で行うのがよく、好ましくは、１７６４〜２４５０Ｎ／ｃｍ（１８０〜２５０ｋｇ／ｃｍ）の範囲の線圧力で行うのが良い。さらに、該カレンダーによる加熱加圧加工は、カレンダー機の１段の処理でもよいが、厚さ方向により均質な紙を得るためには、予備的に加熱加圧処理を施し、２段、あるいは３段以上の多段処理を行うこともできる。
【００３５】
このような加熱加圧加工処理を施すことにより、芳香族ポリアミド繊維紙の嵩密度を、０．４５〜１．１３ｇ／ｃｍ^３、好ましくは、０．５０〜０．８８ｇ／ｃｍ^３、さらに好ましくは、０．５５〜０．７５ｇ／ｃｍ^３の範囲内に入るようにコントロールすることができる。
【００３６】
かくして得られたパラ型芳香族ポリアミド繊維紙は、繊維紙の強力、耐熱性、耐熱寸法安定性に優れ、電気絶縁紙、ハニカム構造を有する複合材素材、またはプリント配線板用基材に好適に使用できる。
【００３７】
【実施例】
以下、実施例により本発明をさらに詳細に説明するが、本発明は以下の内容に限定されるものではない。なお、実施例中における物性の評価方法及び試験片の作成方法は以下の通りである。
【００３８】
（１）パルプの繊維長
カヤーニ繊維長測定器ＦＳ−２００型（バルメット・オートメーション社製）を用いて、レーザー投影法により測定した。
【００３９】
（２）パルプの濾水度
ＪＩＳ Ｐ−８１２１に準じて測定した。
【００４０】
（３）Ｌ／ｌ
パルプと水とを混合し、固形分濃度を０．２％としたスラリーから、パルプを任意に１０本取り出し、パルプの全体が視野に収まる倍率でそれぞれ光学顕微鏡写真を撮影し、各パルプを構成する主幹部の最大幅Ｌと、そこから派生した、最も太い枝部の最大幅ｌからＬ／ｌを算出し、１０本の平均値を求める。
【００４１】
（４）紙の坪量
ＪＩＳ Ｐ−８１２４に準じて測定した。
【００４２】
（５）紙の厚さ
ＪＩＳ Ｃ−２１１１に準じて測定した。
【００４３】
（６）紙の嵩密度
ＪＩＳ Ｃ−２１１１に準じて測定した。
【００４４】
（７）紙の引張強力
ＪＩＳ Ｐ−８１１３に準じて測定した。
【００４５】
（８）紙の熱寸法変化率
高精度二次元座標測定機（ムトウ工業株式会社製）を用い、長さ２５０ｍｍ、幅５０ｍｍの試料の長さ方向について、熱処理前と温度２８０℃で５分間熱処理した後の長さを測定し、下記計算式により熱寸法変化率を算出した。なお、測定用の試料は、連続紙の長さ方向と幅方向から採取して測定し、その平均値で比較判定した。
【００４６】
【数１】

【００４７】
（９）パラ型芳香族ポリアミドパルプの作成
パラ型芳香族ポリアミド（ポリパラフェニレンテレフタルアミド）繊維からなる単糸繊度１．６８ｄｔｅｘ、繊維長５ｍｍの短繊維（テイジントワロン（株）製「トワロン」）と水とを混合し、固形分の比率が４％であるスラリーを作成した。
【００４８】
このスラリーをディスクリファイナー（熊谷理機工業（株）製）にてディスク間のクリアランスを０．０２ｍｍにして３回通し、パルプを得た。このパルプの繊維長は１．７ｍｍ、濾水度は２７６ｍｌ、Ｌ／ｌは２５であった。
【００４９】
［実施例１、２］
上記（９）で得たパルプと、コポリパラフェニレン・３，４’−オキシジフェニレン・テレフタルアミド繊維からなる単糸繊度１．６７ｄｔｅｘ、繊維長３ｍｍの短繊維（帝人（株）製「テクノーラ」）とを表１に示す割合で混合し、パルパーにより水中に離解分散させる際に、分散剤（松本油脂（株）製、「ＹＭ−８０」）を添加して、繊維濃度０．１５重量％の抄紙用スラリーを作成した。
【００５０】
次にタッピー式角型手抄機を使用し、該抄紙用スラリー液を用いて抄紙し、軽く加圧脱水した後、温度１６０℃の熱風乾燥機中で約１５分間乾燥して、パラ型芳香族ポリアミド繊維紙状物を得た。
【００５１】
ついで、該芳香族ポリアミド繊維紙状物を、直径：約２５０ｍｍの一対の硬質表面金属ロールからなるカレンダー機を用いて、温度：２３０℃、線圧：１５６８Ｎ（１６０ｋｇ）／ｃｍの条件で加熱、加圧した後、さらに、直径：約３００ｍｍの一対の硬質表面金属ロールからなるカレンダー機を用い、温度：３２０℃、線圧：１９６０Ｎ（２００ｋｇ）／ｃｍの条件で加熱、加圧して、実質的にパラ型芳香族ポリアミドからなる繊維紙を得た。
【００５２】
得られた芳香族ポリアミド繊維紙の特性を表２に示す。
【００５３】
［実施例３］
実施例１において、コポリパラフェニレン・３，４’−オキシジフェニレン・テレフタルアミドに代えて、ポリパラフェニレンテレフタルアミドからなる単繊維繊度１．６１ｄｔｅｘ（１．４５ｄｅ）、カット長３ｍｍの短繊維（テイジントワロン（株）製「トワロン」）を用いた以外は実施例１と同様に行ってパラ型芳香族ポリアミド繊維紙を得た。
【００５４】
得られた芳香族ポリアミド繊維紙の特性を表２に示す。
【００５５】
［実施例４］
実施例２において、コポリパラフェニレン・３，４’−オキシジフェニレン・テレフタルアミドに代えて、ポリパラフェニレンテレフタルアミドからなる単繊維繊度１．６１ｄｔｅｘ（１．４５ｄｅ）、カット長３ｍｍの短繊維（テイジントワロン（株）製「トワロン」）を用いた以外は実施例２と同様に行ってパラ型芳香族ポリアミド繊維紙を得た。
【００５６】
得られた芳香族ポリアミド繊維紙の特性を表２に示す。
【００５７】
［比較例１］
パラ型芳香族ポリアミド（ポリパラフェニレンテレフタルアミド）繊維からなる単糸繊度１．６８ｄｔｅｘ、繊維長５ｍｍの短繊維（テイジントワロン（株）製「トワロン」）と水とを混合し、固形分の比率が０．２％であるスラリーを作成した。該スラリーをディスクリファイナー（熊谷理機工業（株）製）にてディスク間のクリアランスを０．０２ｍｍにして５回通し、繊維長が１．４ｍｍ、濾水度が２２５ｍｌ、Ｌ／ｌが４８であるパルプを得た。
【００５８】
このパルプを、上記（９）で得たパルプに代えて用いた以外は実施例１と同様に実施してパラ型芳香族ポリアミド紙を得た。
【００５９】
得られた芳香族ポリアミド繊維紙の特性を表２に示す。
【００６０】
［比較例２］
実施例３において、上記（９）で得たパルプに代えて比較例１で使用したパルプを用いた以外は実施例３と同様に実施した。
【００６１】
得られた芳香族ポリアミド繊維紙の特性を表２に示す。
【００６２】
［比較例３］
実施例１において、上記（９）で得たパルプに代えて、ポリメタフェニレンイソフタルアミド（デュポン（株）製「ノーメックス」）からなり、繊維長が１．２ｍｍ、濾水度が７０ｍｌである（燐片形状のためＬ／ｌは測定不可）フィブリッドを用いた以外は実施例１と同様に実施した。
【００６３】
得られた芳香族ポリアミド繊維紙の特性を表２に示す。
【００６４】
［比較例４］
実施例１において、上記（９）で得たパルプを使用せず、コポリパラフェニレン・３，４’−オキシジフェニレン・テレフタルアミド繊維からなる短繊維のみを湿式抄造した後、ビスフェノールＡエピクロルヒドリン型水分散性エポキシ樹脂バインダー（大日本インキ化学工業（株）製）の水希釈液（固形分濃度：２重量％）を、該樹脂の固形分付着量が１０重量％になるようにスプレーした以外は実施例１と同様に実施した。
【００６５】
得られた芳香族ポリアミド繊維紙の特性を表２に示す。
【００６６】
【表１】

【００６７】
【表２】

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a para-type aromatic polyamide pulp and a para-type aromatic polyamide fiber paper containing the pulp as a binder component. More specifically, the present invention relates to a para-type aromatic material which can be suitably used for an electrical insulating paper, a composite material having a honeycomb structure, or a substrate for a printed wiring board, which is used particularly in a field where heat resistance and high strength are required. The present invention relates to a polyamide pulp and a para-type aromatic polyamide fiber paper containing the pulp as a binder component.
[0002]
[Prior art]
Para-type aromatic polyamide fibers have excellent properties such as high strength, high rigidity and high heat resistance, and para-type aromatic polyamide pulp produced from the para-type aromatic polyamide fibers is used as an asbestos substitute material in industry. It is used for various purposes for consumer and consumer use.
[0003]
In particular, in recent years, various studies have been made to form a sheet by utilizing a binder property due to entanglement between pulp, in addition to high strength, high rigidity, and high heat resistance, and to use the sheet as a base material of a laminate for a printed circuit board. However, the para-type aromatic polyamide fibers have a problem in that the fibers do not adhere to each other, so that the strength of the fibers cannot be sufficiently exhibited when a sheet is formed.
[0004]
In order to solve such a problem, for example, JP-A-2-203589 discloses an aromatic polyamide fiber paper comprising a para-type aromatic polyamide fiber and an organic resin binder, and JP-A-7-3693. Discloses a method for producing paper, characterized in that wet paper after paper-making substantially consisting of para-type aromatic polyamide is dried under pressure.
[0005]
However, in the former fiber paper, the glass transition point of the organic resin binder used to bind the fibers is significantly lower than that of the para-type aromatic polyamide fiber, so that when the resin is heated, There is a problem that the binder component is re-melted, the bonding between the fibers becomes unstable, and a large dimensional change occurs in a high temperature region.
[0006]
On the other hand, although the latter fiber paper certainly improves heat resistance, it has a problem that sufficient strength as paper cannot be obtained due to weak entanglement effect.
[0007]
Further, Japanese Patent Application Laid-Open No. 2000-273788 discloses a method for producing paper using a para-type aromatic polyamide pulp having a freeness of 10 ml or less, but using a pulp having a freeness of 10 ml or less. In this case, the entanglement between the pulp is too large, the dispersion of the short fibers during the papermaking becomes uneven, and the fiber length of the pulp becomes short. There was a problem that it would be enough.
[0008]
[Patent Document 1]
JP-A-2-203589
[Patent Document 2]
JP-A-7-3693
[Patent Document 3]
JP 2000-273788 A
[Problems to be solved by the invention]
An object of the present invention is to solve the above-mentioned problems of the prior art, and to have high binder performance and impair the features of para-type aromatic polyamide fibers, such as high strength, high heat resistance, and high heat dimensional stability. An object of the present invention is to provide a para-type aromatic polyamide pulp capable of producing paper without the need.
[0012]
[Means for Solving the Problems]
The present inventors have conducted intensive studies to achieve the above object, and as a result, compared to conventional pulp, the degree of fibrillation is coarse, but more uniformly fibrillated para-type aromatic polyamide pulp is used as a binder component. It was determined that the desired para-type aromatic polyamide fiber paper could be obtained when used, and reached the present invention.
[0013]
That is, according to the present invention, a pulp formed from a para-type aromatic polyamide, having a total length of 0.5 to 5 mm and a freeness measured based on JIS P 8121 (Canadian standard type). A para-type aromatic polyamide pulp is provided, wherein the p-type aromatic polyamide pulp is more than 10 and 500 ml or less, and L / l measured by the following method is 40 or less.
[0014]
<Method of measuring L / l>
Arbitrarily take out 10 pulp from a slurry obtained by mixing pulp and water and having a solid concentration of 0.2%, and take an optical microscope photograph at a magnification that allows the entire pulp to be in the field of view, and constitute each pulp. Then, L / l is calculated from the maximum width L of the main part to be processed and the maximum width l of the thickest branch part derived therefrom, and an average value of 10 pieces is obtained.
[0015]
Further, according to the present invention, there is provided a para-type aromatic polyamide fiber paper comprising para-type aromatic polyamide staple fibers as a main component and the above-mentioned para-type aromatic polyamide pulp as a binder component. .
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail.
[0017]
The para-type aromatic polyamide used in the present invention means that at least 80 mol% (preferably at least 90 mol%) of the repeating unit constituting the polyamide is an aromatic homopolyamide represented by the following formula (1) or an aromatic homopolyamide represented by the following formula (1). It is made of group copolyamide.
[0018]
Embedded image

[0019]
Here, Ar ₁ and Ar ₂ each represent an aromatic group, of which 50 mol% or more is preferably composed of the same or different para-coordinated aromatic groups selected from the following formula (2). However, the hydrogen atom of the aromatic group may be substituted with a halogen atom, a lower alkyl group, a phenyl group, or the like.
[0020]
Embedded image

[0021]
The production method and fiber properties of such aromatic polyamide fibers are described in, for example, British Patent No. 1501948, U.S. Pat. No. 3,733,964, U.S. Pat. No. 3,767,756, and 3,869,429. JP-A-49-100322, JP-A-47-10863, JP-A-58-144152, JP-A-4-65513, and the like, which are particularly excellent in heat resistance. Specific examples of the type aromatic polyamide include polyparaphenylene terephthalamide fibers ("Kevlar" manufactured by DuPont, "Twaron" manufactured by Teijin Twaron Co., Ltd.), and copolyparaphenylene-3,4'-oxydiphenylene. -Examples include terephthalamide fibers ("Technola" manufactured by Teijin Limited).
[0022]
The para-type aromatic polyamide pulp of the present invention comprises the above-mentioned para-type aromatic polyamide, and has a fiber length of 0.5 mm to 5 mm, preferably 0.6 mm to 3 mm. When the fiber length is less than 0.5 mm, pulp falls off during papermaking. On the other hand, when the fiber length exceeds 5 mm, dispersibility and formation during papermaking deteriorate.
[0023]
The para-type aromatic polyamide pulp of the present invention needs to have a freeness of more than 10 and not more than 500 ml. If the freeness is 10 ml or less, the entanglement between the pulp becomes too large, the dispersibility at the time of paper making becomes poor, and the uniformity of the fiber density distribution is deteriorated. On the other hand, when the freeness exceeds 500 ml, fibrillation is small and only pulp with short fibrils can be obtained. Can not be done.
[0024]
Furthermore, it is important that the para-type aromatic polyamide pulp of the present invention has an L / l of 40 or less as measured by the following method.
[0025]
Here, as a method for measuring L / l, 10 pulp fibers were arbitrarily taken out from a slurry in which pulp fibers and water were mixed to obtain a solid content concentration of 0.2%, and each pulp was entirely removed. An optical microscope photograph is taken at a magnification that fits in the field of view, and L / l is calculated from the maximum width L of the main trunk constituting the pulp and the maximum width l of the thickest branch derived therefrom, and an average value of 10 is obtained. .
[0026]
As a method for producing a pulp having such a value of L / l, for example, a short fiber made of a para-type aromatic polyamide cut to a predetermined length is mixed with water to have a solid content of 2% or more. After making such a slurry, beating it by passing it between two disks rotating with a clearance of 0.03 mm or less several times, or applying mechanical shearing force using a crusher such as a ball mill, It can be produced by beating.
[0027]
When the mixed paper made of para-aromatic polyamide short fibers is produced using the para-aromatic polyamide pulp, the para-aromatic polyamide short fibers are 30 to 90% of the total weight of the paper, preferably 30 to 90%. It is better to be 40 to 85%.
[0028]
At this time, the single fiber fineness of the para-type aromatic polyamide short fibers used is preferably 0.11 to 5.56 dtex (0.1 to 5.0 de). If the single-fiber fineness is less than 0.11 dtex, there are many difficulties in the yarn-making technology, and it may be difficult to stably produce fibers of good quality due to yarn breakage and fluffing, and also cost. May also be high, which is not preferable. On the other hand, if the single fiber fineness exceeds 5.56 dtex, the entanglement between the fibers is reduced, and the strength is sometimes greatly reduced.
[0029]
The fiber length of such an aromatic polyamide short fiber is preferably in the range of 1 to 60 mm. Particularly, when the paper is formed by a wet method, the fiber length in the range of 2 to 12 mm is optimal. . If the fiber length is less than 1 mm, the mechanical properties of the obtained aromatic polyamide fiber paper (fiber aggregate) may be insufficient, which is not preferable. On the other hand, when the fiber length exceeds 60 mm, the dispersibility of short fibers is deteriorated during papermaking, so that the uniformity of the obtained fiber aggregate is impaired, and the mechanical properties may still be insufficient.
[0030]
The binder component other than the para-aromatic polyamide pulp, for example, a fibrid or undrawn fiber composed of a meta-aromatic polyamide, a wholly aromatic polyester, as long as the properties inherent in the para-aromatic polyamide pulp are not impaired. Pulp, an organic resin binder, or the like may be added. In this case, the proportion of the para-type aromatic polyamide pulp in all the binder components is 70% by weight or more, preferably 80% by weight or more, more preferably 90% by weight or more.
[0031]
As described above, when a mixed paper made of para-aromatic polyamide short fibers is produced using para-aromatic polyamide pulp, it can be produced by a conventionally known method. For example, the above-mentioned para-type aromatic polyamide short fiber and the above-mentioned para-type aromatic polyamide pulp are weighed so as to have a predetermined ratio, and put into water such that the fiber concentration becomes about 0.15 to 0.40% by weight. In the aqueous slurry uniformly dispersed and then, if necessary, after adding a dispersant and a viscosity modifier, to form a wet paper by a wet papermaking method with a paper machine such as a long net or a round net, If necessary, wet paper can be obtained by applying an organic binder resin to a predetermined solid content ratio by a spray method or the like, and then drying and heating and pressing to obtain a para-type aromatic polyamide fiber paper. .
[0032]
For example, in the case of performing heat-pressing processing using a calender, between a hard surface roll having a diameter of about 15 to 80 cm and a surface-deformable elastic roll having a diameter of about 30 to 100 cm. Or, more preferably, heating and pressing may be performed between two hard surface rolls having a diameter of about 20 to 80 cm.
[0033]
At that time, in order to sufficiently exhibit the binder performance of the para-type aromatic polyamide pulp, it is preferable to perform heating and pressing in a temperature range of 220 to 400 ° C, preferably, 250 to 350 ° C, more preferably, Excellent bonding results can be obtained by performing in a temperature range of 280 ° C to 330 ° C.
[0034]
The pressure is preferably set at a linear pressure in a range of 1470 to 2450 N / cm (150 to 250 kg / cm), and preferably a linear pressure in a range of 1764 to 2450 N / cm (180 to 250 kg / cm). It is good to do in. Further, the heat and pressure processing by the calender may be performed in one stage of a calender machine. However, in order to obtain a more uniform paper in the thickness direction, preliminary heat and pressure treatment is performed and two or three stages are performed. Multi-stage processing of more than stages can also be performed.
[0035]
By performing such heat-pressing processing, the bulk density of the aromatic polyamide fiber paper is 0.45 to 1.13 g / cm ³ , preferably 0.50 to 0.88 g / cm ³ , and more preferably. Can be controlled to fall within the range of 0.55 to 0.75 g / cm ³ .
[0036]
The para-type aromatic polyamide fiber paper thus obtained is excellent in the strength, heat resistance and heat resistance dimensional stability of the fiber paper, and is suitable for electric insulating paper, a composite material having a honeycomb structure, or a substrate for a printed wiring board. Can be used.
[0037]
【Example】
Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to the following contents. The methods for evaluating physical properties and the method for preparing test pieces in the examples are as follows.
[0038]
(1) Pulp fiber length The fiber length was measured by a laser projection method using a Kajaani fiber length measuring instrument FS-200 (manufactured by Valmet Automation).
[0039]
(2) Freeness of pulp Measured according to JIS P-8121.
[0040]
(3) L / l
Arbitrarily take out 10 pulp from a slurry obtained by mixing pulp and water and having a solid concentration of 0.2%, and take an optical microscope photograph at a magnification that allows the entire pulp to be in the field of view, and constitute each pulp. Then, L / l is calculated from the maximum width L of the main part to be processed and the maximum width l of the thickest branch part derived therefrom, and an average value of 10 pieces is obtained.
[0041]
(4) Basis weight of paper Measured according to JIS P-8124.
[0042]
(5) Paper thickness Measured according to JIS C-2111.
[0043]
(6) Bulk density of paper Measured according to JIS C-2111.
[0044]
(7) Tensile strength of paper Measured according to JIS P-8113.
[0045]
(8) Heat dimensional change rate of paper Using a high-precision two-dimensional coordinate measuring machine (manufactured by Mutou Kogyo Co., Ltd.), heat-treating the sample in the length direction of 250 mm in length and 50 mm in width at 280 ° C. for 5 minutes before heat treatment The length after the measurement was measured, and the thermal dimensional change was calculated by the following formula. In addition, the sample for measurement was taken from the length direction and the width direction of the continuous paper and measured, and the average value thereof was compared and determined.
[0046]
(Equation 1)

[0047]
(9) Preparation of para-type aromatic polyamide pulp Single fiber fineness of 1.68 dtex and fiber length of 5 mm made of para-type aromatic polyamide (polyparaphenylene terephthalamide) fiber ("Twaron" manufactured by Teijin Twaron Co., Ltd.) And water were mixed to prepare a slurry having a solid content of 4%.
[0048]
This slurry was passed three times with a disc refiner (manufactured by Kumagai Riki Kogyo Co., Ltd.) with the clearance between the discs being 0.02 mm to obtain pulp. The fiber length of this pulp was 1.7 mm, the freeness was 276 ml, and L / l was 25.
[0049]
[Examples 1 and 2]
Short fiber with a single fiber fineness of 1.67 dtex and a fiber length of 3 mm composed of the pulp obtained in the above (9) and copolyparaphenylene / 3,4'-oxydiphenylene / terephthalamide fiber ("Technola" manufactured by Teijin Limited) ) Were mixed at a ratio shown in Table 1 and disintegrated and dispersed in water by a pulper. A dispersant ("YM-80", manufactured by Matsumoto Yushi Co., Ltd.) was added, and the fiber concentration was 0.15% by weight. Was prepared.
[0050]
Next, using a tappy type square hand machine, papermaking is performed using the slurry for papermaking, lightly dewatered under pressure, and then dried in a hot air drier at a temperature of 160 ° C. for about 15 minutes to obtain a para-type fragrance. A group III polyamide fiber paper was obtained.
[0051]
Then, the aromatic polyamide fiber paper was heated at a temperature of 230 ° C. and a linear pressure of 1568 N (160 kg) / cm using a calender comprising a pair of hard surface metal rolls having a diameter of about 250 mm. After pressurizing, further, using a calendering machine consisting of a pair of hard surface metal rolls having a diameter of about 300 mm, heating and pressurizing at a temperature of 320 ° C. and a linear pressure of 1960 N (200 kg) / cm, substantially Thus, a fiber paper made of para-type aromatic polyamide was obtained.
[0052]
Table 2 shows the properties of the obtained aromatic polyamide fiber paper.
[0053]
[Example 3]
In Example 1, in place of copolyparaphenylene-3,4'-oxydiphenylene terephthalamide, a single fiber fineness of 1.61 dtex (1.45 de) made of polyparaphenylene terephthalamide and a short fiber having a cut length of 3 mm ( A para-type aromatic polyamide fiber paper was obtained in the same manner as in Example 1 except for using "Twaron" manufactured by Teijin Twaron Co., Ltd.).
[0054]
Table 2 shows the properties of the obtained aromatic polyamide fiber paper.
[0055]
[Example 4]
In Example 2, a single fiber fineness of 1.61 dtex (1.45 de) made of polyparaphenylene terephthalamide instead of copolyparaphenylene / 3,4'-oxydiphenylene terephthalamide, and a short fiber with a cut length of 3 mm ( A para-type aromatic polyamide fiber paper was obtained in the same manner as in Example 2 except that "Twaron" manufactured by Teijin Twaron Ltd.) was used.
[0056]
Table 2 shows the properties of the obtained aromatic polyamide fiber paper.
[0057]
[Comparative Example 1]
A single fiber fineness of 1.68 dtex composed of para-type aromatic polyamide (polyparaphenylene terephthalamide) fiber and a short fiber having a fiber length of 5 mm ("Twaron" manufactured by Teijin Twaron Co., Ltd.) and water are mixed, and the ratio of solid content Was 0.2%. The slurry was passed through a disc refiner (manufactured by Kumagai Riki Kogyo Co., Ltd.) five times with the clearance between the discs being 0.02 mm, and the fiber length was 1.4 mm, the freeness was 225 ml, and the L / l was 48. I got some pulp.
[0058]
This pulp was used in the same manner as in Example 1 except that the pulp obtained in the above (9) was used, to obtain a para-type aromatic polyamide paper.
[0059]
Table 2 shows the properties of the obtained aromatic polyamide fiber paper.
[0060]
[Comparative Example 2]
Example 3 was carried out in the same manner as in Example 3 except that the pulp used in Comparative Example 1 was used instead of the pulp obtained in the above (9).
[0061]
Table 2 shows the properties of the obtained aromatic polyamide fiber paper.
[0062]
[Comparative Example 3]
In Example 1, instead of the pulp obtained in the above (9), it is made of polymetaphenylene isophthalamide ("Nomex" manufactured by DuPont), the fiber length is 1.2 mm, and the freeness is 70 ml ( (L / l cannot be measured due to the shape of the scale).
[0063]
Table 2 shows the properties of the obtained aromatic polyamide fiber paper.
[0064]
[Comparative Example 4]
In Example 1, without using the pulp obtained in (9) above, only short fibers composed of copolyparaphenylene / 3,4'-oxydiphenylene / terephthalamide fibers were wet-processed, and then bisphenol A epichlorohydrin type water was used. A water diluent (solid content: 2% by weight) of a dispersible epoxy resin binder (manufactured by Dainippon Ink and Chemicals, Inc.) was sprayed so that the solid content of the resin was 10% by weight. It carried out similarly to Example 1.
[0065]
Table 2 shows the properties of the obtained aromatic polyamide fiber paper.
[0066]
[Table 1]

[0067]
[Table 2]

Claims (3)

A pulp formed from a para-type aromatic polyamide, wherein the pulp has a total length of 0.5 to 5 mm, a freeness measured in accordance with JIS P 8121 (Canadian standard form) of more than 10 and not more than 500 ml, and A para-type aromatic polyamide pulp, wherein L / l measured by the following method is 40 or less.
<Method of measuring L / l>
Arbitrarily take out 10 pulp from a slurry obtained by mixing pulp and water and having a solid concentration of 0.2%, and take an optical microscope photograph at a magnification that allows the entire pulp to be in the field of view, and constitute each pulp. Then, L / l is calculated from the maximum width L of the main part to be processed and the maximum width l of the thickest branch part derived therefrom, and an average value of 10 pieces is obtained. The para type aromatic polyamide pulp according to claim 1, wherein the para type aromatic polyamide fiber is a polyparaphenylene terephthalamide fiber and / or a copolyparaphenylene / 3,4'-oxydiphenylene terephthalamide fiber. A para-aromatic polyamide fiber paper comprising para-aromatic polyamide short fibers as a main component and the para-aromatic polyamide pulp according to claim 1 or 2 as a binder component.