JP3769780B2 - Laminated body - Google Patents

Description

【００２２】
で示される単位から構成される、耐薬品性およびダスト剥離性に非常に優れる芳香族ポリイミドである。
【００２３】
ここで、上記一般式におけるＲは、一般式
【００２４】
【化２】

【００２５】
で示される基、および、一般式
【００２６】
【化３】

【００２７】
で示される基である。
【００２８】
上記ポリイミドは、通常、ベンゾフェノンテトラカルボン酸二無水物、トリレンジイソシアネート、およびメチレンジフェニルジイソシアネートを、非プロトン性有機溶媒中で反応させることにより調製され得る。
【００２９】
このような芳香族ポリイミドは、例えば、レンチング社（ＬｅｎｚｉｎｇＡＧ）よりポリイミド「Ｐ８４」（登録商標）として市販されている。
【００３０】
本発明で用いられるポリテトラフルオロエチレンは、従来より公知であり、以下の一般式
【００３１】
【化４】

【００３２】
で示される単位から構成される。
【００３３】
上記ポリテトラフルオロエチレンは、例えば、テトラフルオロエチレンを、少量の酸素を触媒として２２００〜１６００ｐｓｉの圧力下にて重合することにより得られる。
【００３４】
本発明に用いられる基布は、得られる積層体の通気性が大きく損なわれず、得られる積層体の強度および寸法安定性を向上するという目的が達成される限り、繊維から形成される基布、フィルム状成形体、スリットヤーンからの成形体、網状成形体などであり得る。絡合に用いられるニードルパンチ時の被損傷性の点から、繊維から形成される基布が好ましい。
【００３５】
本発明に用いる基布は、上記ポリイミドおよびポリテトラフルオロエチレンから各々乾式紡糸法、ペースト抽出法などの方法により形成されたポリイミド繊維およびポリテトラフルオロエチレン繊維を用いて形成されるモノフィラメント糸またはマルチフィラメント糸を、単独でまたは組み合わせて、平織、モクレノ織、綾織などに製織することにより、好適に形成され得る。
【００３６】
上記基布の形成に用いられるポリイミドおよび／またはポリテトラフルオロエチレンモノフィラメント糸またはマルチフィラメント糸は、５０デニール〜２０００デニール、好ましくは２００デニール〜１５００デニール、さらに好ましくは、３００デニール〜１０００デニールの範囲の繊度を有する。繊度が５０デニール未満では得られる積層体の強度に劣り、２０００デニールを越えると厚さが大きくなりすぎるおそれがある。
【００３７】
上記基布の密度は、製織方法により異なるが、基布が平織に製織される場合には、その密度は１０〜１００本／５ｃｍ、好ましくは１６〜８０本／５ｃｍである。密度が１０本／５ｃｍ未満では形態不安定であり、１００本／ｃｍを越えると通気性不良のおそれがある。基布がモクレノ織に製織されている場合には、その密度は１６〜１００本／５ｃｍ、好ましくは２０〜８０本／ｃｍである。密度が１６本／５ｃｍ未満では形態不安定であり、１００本／ｃｍを越えると通気性不良のおそれがある。
【００３８】
上記基布は、縦方向の引張強力が４０〜２００ｋｇｆ／５ｃｍ幅、好ましくは、５０〜１２０ｋｇｆ／５ｃｍ幅、さらに好ましくは、６０〜１１０ｋｇｆ／５ｃｍ幅である。縦方向の引張強力が４０ｋｇｆ／５ｃｍ幅に未満では、後述のウェブを積層して、好ましくはニードルパンチ絡合させることにより形成される積層体の縦引張強力が４０ｋｇｆ／５ｃｍ幅未満となる。その結果、バグフィルター用濾布として使用すると、短時間で破損、穴あきの恐れがあり好ましくない。逆に、縦方向の引張強力が２００ｋｇｆ／５ｃｍ幅を越えると、強度的には問題はないが、過剰品質となり、さらに、上記繊維のような基布構成材料を必要以上の量で使用することとなるため、コスト面で好ましくない。
【００３９】
ここで、上記「引張強力」とは、ＪＩＳ Ｌ １０９６ ６．１２．１（１）Ａ法カットストリップ法に準じて、定速伸長形引張試験機にて試験片の幅５ｃｍ、つかみ間隔２０ｃｍ、引張速度２０ｃｍ／分で測定される特性である。
【００４０】
本発明に用いられるウェブは、ポリイミドからなる繊維により構成される。
【００４１】
上記ポリイミドとしては、上記基布に用いられるポリイミドと同様のものが用いられる。
【００４２】
上記ポリイミドは、公知の方法を用いて製造されたポリイミドの単糸繊維に、さらに通常の捲縮工程および切断工程を施し、ポリイミド繊維のステープルに加工される。
【００４３】
本発明に用いられるポリイミド繊維は、表面積を大きくし濾過機能を向上させる点から、０．４〜６デニール、好ましくは０．６〜４デニールの繊度、かつ、３０ｍｍ〜２００ｍｍ、好ましくは４０ｍｍ〜１２０ｍｍの繊維長を有することが好ましい。繊度が０．４デニール未満では強度不足であり、６デニールを越えると、通気性不良のおそれがある。繊維長が３０ｍｍ未満では、絡合不足となり、２００ｍｍを越えると開繊不良のおそれがある。
【００４４】
本発明に用いられるウェブは、上記ポリイミド繊維から、目付け５０ｇ／ｍ²〜８００ｇ／ｍ²、好ましくは３００ｇ／ｍ²〜７００ｇ／ｍ²となるように、調合、開繊、カードなどの方法により製造され得る。目付が５０ｇ／ｍ²未満では通気性が大きすぎ、８００ｇ／ｍ²を越えると通気性不良のおそれがある。
【００４５】
本発明の積層体は、上記基布の両面に上記ポリイミド繊維からなるウェブを積層し、次いで、ウェブと基布との間の繊維を、例えば、通常のニードルパンチ、噴射水流などによる絡合を行うことにより得られる。絡合度が高いことから、ニードルパンチ法が好ましい。さらに、必要に応じて形態安定化のために、２５０℃〜３１０℃の高温で０．５分間〜５分間熱処理し、表面をガス毛焼きし、そして表面温度２００℃〜３００℃の熱ロールにて５ｋｇ／ｃｍ〜３０ｋｇ／ｃｍの圧力をかけてプレスが行われる。従って、本発明の積層体は、ウェブに基布が挟まれたサンドイッチ状の構造を有する。
【００４６】
本発明の積層体の乾熱収縮率は、縦方向（長尺方向）および横方向（短尺方向）のいずれにおいても０．８％以下、好ましくは０．６％以下、さらに好ましくは０．４％以下である。乾熱収縮率が０．８％を越えると、高温下での長時間の使用により、支持体であるリテーナーとの寸法的余裕がなくなり、バグ交換時にバグからリテーナーを抜き取ることが困難であったり、使用中のバグ長の収縮によりリテーナーが浮き上がるなどの問題が発生する。
【００４７】
ここで、上記「乾熱収縮率」は、２４０℃で１時間積層体を乾熱処理する前後での積層体の寸法の変化率をいい、下式
【００４８】
【数１】

【００４９】
により求められる。
【００５０】
上記積層体はまた、５〜３０ｍｌ／ｃｍ²／ｓｅｃ、好ましくは、５〜１５ｍｌ／ｃｍ²／ｓｅｃ、さらに好ましくは、７〜１３ｍｌ／ｃｍ²／ｓｅｃの通気性を有する。通気性が５ｍｌ／ｃｍ²／ｓｅｃ未満では、そのような積層体を用いて得られる濾布の使用初期には一時的に優れた集塵効果が得られるが、短時問で濾布が目詰まり状態に達して使用できなくなる。通気性が３０ｍｌ／ｃｍ²／ｓｅｃを越えると、微細ダストが濾布を通過してしまうため、所望の集塵効果が得られない。
【００５１】
ここで、上記「通気性」は、ＪＩＳ−Ｌ−１０９６−６．２７．１Ａ法に準じて、フラジール形試験機で測定される特性である。
【００５２】
上記積層体は、好ましくは１０ｋｇｆ／５ｃｍ幅以下、さらに好ましくは９ｋｇｆ／５ｃｍ幅以下、特に好ましくは８ｋｇｆ／５ｃｍ幅以下の熱応力を有する。熱応力が１０ｋｇｆ／５ｃｍ幅を越える場合には、前記の乾熱収縮率の２４０℃×１時間での値が０．８％以下であっても、リテーナーを浮き上がらせることがあり好ましくない。特に、熱応力が極度に大きい場合には、この積層体を用いて得られる濾布がリテーナーを押し曲げることもあり得る。このような現象は、バグフィルターの設計に依存して起こる。例えば、濾布とリテーナーの寸法差にゆとりがない場合、または、濾布の収縮によりリテーナーが容易に持ち上げられ、かつ、濾布に発生した熱応力がリテーナーを固定する力を上回った場合に、上記現象が生じる。さらに、リテーナーを用いず、濾布の収縮による長さの変化に対応できるように濾布をスプリングによって緊張させた状態で使用する内面濾過方式バグフィルター濾過集塵装置においては、熱応力が１０ｋｇｆ／５ｃｍ幅を越えると、スプリングが伸びてしまったり、破損もしくは破損寸前の状態になることがある。
【００５３】
ここで、上記「熱応力」は、本発明の積層体が一旦加熱されたときに膨張し、次いで冷却されて収縮する時に発生する応力である。
【００５４】
上記熱応力は、積層体の短冊状の試験片に初荷重２ｋｇｆ／５ｃｍ幅を加え、両端を引張試験機のクランプに固定したまま２６０℃で１時間加熱した後、常温中にさらしたときに発生する応力として、以下のように測定され、数値で表される。
【００５５】
積層体から切り出した幅５ｃｍおよび長さ３０ｃｍ（つかみ間隔２０ｃｍ）の試験片の長手方向の両端を把持して、初荷重２ｋｇｆ／５ｃｍ幅を加える。このときの手順としては、上記試験片の一端を引張試験機のクランプに固定し、次いで初荷重を加え、その状態で他の一端をもう一方のクランプに固定する方法、もしくは、試験片の両端をそれぞれのクランプに固定した後、クランプを移動させて初荷重を加える方法が用いられ得る。いずれの場合も、所定の初荷重を加えた後は、測定が終了するまで試験片を固定している両クランプは動かさず、そのまま２６０℃で１時間加熱した後、常温中にさらし、試験片から生じる応力をチャート上で読みとる。本発明では、縦方向の熱応力を測定して、試料の代表値とする。この測定で用いられる初荷重の値は、通常の引張強力測定の場合などと比較して非常に大きいが、それは、測定した熱応力の大きさを判定し易くするためである。
【００５６】
本発明の積層体の応力測定チャート例を図１に示す。図１は、温度と応力の変化を時間に対してプロットしたチャートである。上記測定法では、応力は２６０℃での１時間の加熱を停止した時点から増加し、約３時間半から４時間で一旦横這いになり、その後徐々に下降する。応力が横這いになった点、すなわち最高点を熱応力として読みとり、測定値とする。
【００５７】
本発明の積層体は、油成分の含有量が高いダストのような粘着性成分を含有するダストに対して使用される濾布に用いられる場合には、好ましくは、その両表面上に撥水撥油剤が付与され得る。このことにより、ダストの粘着成分が濾布表面に蓄積し、目詰まりが起こるのが防止され、粘着性ダストの剥離が容易になり得る。
【００５８】
上記撥水撥油剤としては、含フッ素エーテル型ポリウレタン、含フッ素ウレタンオリゴマー、含フッ素ポリアクリレート、ポリテトラフルオロエチレン、ジメチルシロキサン系シリコン、アミノ変性シロキサン系シリコン、エポキシ変性シロキサン系シリコンなどが好適に用いられ得る。高温使用時の撥水撥油性能の点から、含フッ素エーテル型ポリウレタンが最も好ましい。
【００５９】
上記撥水撥油剤の付与方法としては、積層体を撥水撥油剤の溶液に浸漬した後、引き上げてマングルで絞って乾燥させる方法；撥水撥油剤の溶液を積層体表面にコーティングし乾燥する方法；撥水撥油剤の溶液を発泡させて積層体表面にコーティングし乾燥する方法などの従来公知の方法が用いられ得る。
【００６０】
撥水撥油剤の付与量は、好ましくは積層体１００重量部に対して０．５〜１０重量部、さらに好ましくは１〜５重量部の範囲である。付与量が０．５重量部未満では、所望の粘着性ダスト剥離性が得られず、１０重量部を越えると、通気性不良のおそれがある。
【００６１】
以下、本発明の作用について説明する。
【００６２】
本発明の積層体は、耐熱性、耐薬品性、および強度のいずれにも優れるポリイミドおよび／または耐熱性と耐薬品性とに優れるポリテトラフルオロエチレンから構成され、所定の引張強力を有する基布の両面に、ポリイミドから構成されるウェブを有し、該基布と該ウェブがニードルパンチ絡合しているサンドイッチ状の構造と、緻密化され、ガス毛焼きなどで処理された表面状態とを有し、かつ、所定の引張強力、乾熱収縮率、および通気性を有する。従って、微細なダストも濾過され得（即ち、濾過機能が大きく）、かつ、高温応力下、酸性雰囲気下などの厳しい条件下でも、ポリイミドの有する特性が十分に発揮され、耐熱性、耐薬品性、および強度のいずれにも優れ、高温応力下での寸法変化が少ない。
【００６３】
本発明の積層体は、通常、熱応力が所定の範囲にあるため、変形しにくい。
【００６４】
本発明の積層体に撥水撥油剤が付与された場合には、常温および高温のいずれにおいても撥水撥油効果に優れ、そして粘着性ダストによる汚染および目詰まりが起こりにくく、ダストの払い落としが容易である。
【００６５】
【実施例】
以下、実施例によって本発明をさらに詳しく説明するが、本発明はこれらに限定されない。
【００６６】
（実施例１）
９６０デニールのポリイミドマルチフィラメント糸を用いて、縦３０本／５ｃｍおよび横２２本／５ｃｍの密度の平織物を製織した。得られた平織物の引張強力は、縦９１ｋｇｆ／５ｃｍ、横７７ｋｇｆ／５ｃｍであった。この平織物を基布とし、両面に２デニール×６０ｍｍ繊維長のポリイミドステープルからなるウェブを積層した後、ニードルパンチを施して絡合し、２８０℃の高温で３分間熱処理し、表面をガス毛焼きし、そして表面温度２００℃の熱ロールにて２０ｋｇ／ｃｍの圧力をかけてプレスすることにより、目付５１２ｇ／ｍ²および厚さ２．０ｍｍの積層体を得た。
【００６７】
（実施例２）
実施例１と同じポリイミドマルチフィラメント糸を用いて、縦２５本／５ｃｍおよび横２０本／５ｃｍの密度の平織物を製織し、この平織物を基布とし、両面に２デニール×６０ｍｍ繊維長のポリイミドステープルからなるウェブを積層した後、ニードルパンチを施して絡合し、３００℃の高温で３分間熱処理し、表面をガス毛焼きし、そして表面温度２５０℃の熱ロールにて２０ｋｇ／ｃｍの圧力をかけてプレスすることにより、目付５０８ｇ／ｍ²および厚さ１．９ｍｍの積層体を得た。
【００６８】
（実施例３）
実施例２で製織した平織物と同じ織物を基布とし、両面に２デニール×６０ｍｍ繊維長のポリイミドステープルからなるウェブを積層した後、ニードルパンチを施して絡合することにより積層体を得た。次いで、得られた積層体を、含フッ素エーテル型ポリウレタンからなる撥水撥油剤に浸漬した後引き上げ、マングルで絞って乾燥させることにより、撥水撥油剤を付与した。さらに、この積層体を、３００℃の高温で３分間熱処理した後、表面をガス毛焼きし、表面温度２５０℃の熱ロールにて２０ｋｇ／ｃｍの圧力をかけてプレスすることにより、目付４９８ｇ／ｍ²および厚さ２．１ｍｍの積層体を得た。
【００６９】
（実施例４）
４００デニールのポリテトラフルオロエチレン（ＰＴＦＥ）モノフィラメント糸を用いて縦６０本／５ｃｍ、横６０本／５ｃｍの密度のモクレノ織物を製織した。仕上がった織物の引張強力は縦７５ｋｇｆ／５ｃｍ、横７６ｋｇｆ／５ｃｍであった。このモクレノ織物を基布とし、両面に２デニール×６０ｍｍ繊維長のポリイミドステープルからなるウェブを積層しニードルパンチを施し、２８０℃の高温で３分間熟処理の後、表面をガス毛焼きし、表面温度２００℃の熱ロールにて２０ｋｇ／ｃｍの圧力をかけプレスし、目付５１７ｇ／ｍ²および厚さ１．９ｍｍの積層体を得た。
【００７０】
（実施例５）
撥水撥油剤として含フッ素ポリアクリレートを用いたこと以外は実施例３と同様にして、目付４９９ｇ／ｍ²および厚さ２．１ｍｍの積層体を得た。
【００７１】
（比較例１）
９６０デニールのポリイミドマルチフィラメント糸を用いて、縦３０本／５ｃｍ、横２２本／５ｃｍの密度の平織物を製織した。仕上がった平織物の引張強力は、縦９３ｋｇｆ／５ｃｍ、横７８ｋｇｆ／５ｃｍであった。この平織物を基布とし、両面に２デニール×６０ｍｍ繊維長のポリイミドステープルからなるウェブを積層しニードルパンチを施し、２５０℃の温度で３分間熱処理の後、表面をガス毛焼きし、表面温度２００℃の熱ロールにて２０ｋｇ／ｃｍの圧力をかけプレスし、目付５２０ｇ／ｍ²および厚さ２．２ｍｍの積層体を得た。
【００７２】
（比較例２）
実施例２と同じ縦２５本／５ｃｍ、横２０本／５ｃｍの密度のポリイミド平織物を基布とし、両面に２デニール×６０ｍｍ繊維長のポリイミドステープルからなるウェブを積層しニードルパンチを施し、３００℃の温度で３分間熱処理の後、表面をガス毛焼きし、表面温度２００℃の熱ロールにて５ｋｇ／ｃｍの圧力をかけプレスし、目付４９５ｇ／ｍ²および厚さ２．４ｍｍの積層体を得た。
【００７３】
（比較例３）
４５０デニールのポリイミドマルチフィラメント糸を用いて縦５０本／５ｃｍ、横４０本／５ｃｍの密度の平織物を製織した。仕上がった平織物の引張強力は縦７１ｋｇｆ／５ｃｍ、横６８ｋｇｆ／５ｃｍであった。この平織物を基布とし、両面に２デニール×６０ｍｍ繊維長のポリイミドステープルからなるウェブを積層しニードルパンチを施し、３００℃の高温で３分間熱処理の後、表面をガス毛焼きし、表面温度２５０℃の熱ロールにて、２０ｋｇ／ｃｍの圧力をかけプレスし、目付５０９ｇ／ｍ²および厚さ１．９ｍｍの積層体を得た。
【００７４】
（比較例４）
比較例３と同じポリイミドマルチフィラメント糸を用いて縦６０本／５ｃｍ、横４６本／５ｃｍの平織物を製織し、これを基布とし、両面に２デニール×６０ｍｍ繊維長のポリイミドステープルからなるウェブを積層しニードルパンチを施し、表面をガス毛焼きした後、表面温度２５０℃の熱ロールにて２０ｋｇ／ｃｍの圧力をかけプレスし、目付５１７ｇ／ｍ²および厚さ２．２ｍｍの積層体を得た。
【００７５】
積層体の評価
上記実施例および比較例で得られた各積層体を用いて、以下の項目（ａ）〜（ｄ）について評価した。
【００７６】
（ａ）引張強力
ＪＩＳ Ｌ １０９６ ６．１２．１（１）Ａ法カットストリップ法に準じて、上記実施例および比較例で得られた各積層体から切り出した幅５ｃｍおよび長さ３０ｃｍ（つかみ間隔２０ｃｍ）の試験片を、定速伸長形引張試験機にて引張速度２０ｃｍ／分で測定することにより、引張強力を評価した。
【００７７】
（ｂ）乾熱収縮率
上記実施例および比較例で得られた各積層体から、幅３０ｃｍおよび長さ３０ｃｍの試験片を切り出した。得られた試験片に長さ２５ｃｍの標準線を縦横それぞれ５本ずつ記した後、正確に長さを測定しておき、送風循環型オーブンを用いて２４０℃で１時間加熱し、次いで２０℃、相対湿度６５％の条件下で放冷した後、各標準線の長さを測定し、下式
【００７８】
【数２】

【００７９】
により、乾熱収縮率を求めて平均した。
【００８０】
（ｃ）通気性
ＪＩＳ−Ｌ−１０９６−６．２７．１Ａ法に準じて、フラジール形試験機で、上記実施例および比較例で得られた各積層体を測定することにより、通気性を評価した。
【００８１】
（ｄ）熱応力
上記実施例および比較例で得られた積層体をそれぞれ幅５ｃｍおよび長さ３０ｃｍに切り出し、試験片を得た。このとき、長尺方向に長さを取るようにした。得られた試験片の一端を引張試験機のクランプに固定し、２ｋｇｆ／５ｃｍ幅の初荷重を加えた状態で、他の一端をもう一方のクランプに固定した。所定の初荷重を加えた後は、測定が終了するまで試験片を固定している両クランプは動かさない。温度を記録しながら、この状態の試験片を２６０℃で１時間加熱した後、常温中にさらし、試験片から生じる縦方向の応力を記録し、得られたチャート上の最大応力を熱応力値として読みとった。
【００８２】
濾布の評価
さらに、上記実施例および比較例で得られた各積層体を用いて、都市ゴミ焼却炉に用いられるバグフィルター濾過集塵装置（ＮＫＫ（株）製「密閉ボトムインレット」）用の濾布（直径１６４ｍｍ×長さ５２００ｍｍの袋型）を作製した。比較例２で得られた濾布以外の濾布は全て、同時期に使用を開始し、同条件で使用し、以下の項目（ｅ）〜（ｇ）について、９ヶ月目に一度評価を行い、寸法変化が認められた濾布は交換した。この時点で寸法変化が認められなかった濾布はそのまま継続して使用し、１２ヶ月目に上記項目について評価した。
【００８３】
上記濾布による集塵の対象ガスは、温度が２３０℃〜２４０℃、水分率が５％〜３０％、ＨＣｌ濃度が３００ｍｇ／Ｎｍ³、ＳＯ_x濃度が１２０ｐｐｍ、ＮＯ_x濃度が１００ｐｐｍ、および見かけ濾過速度が１．２ｍ／分であった。
【００８４】
比較例２で得られた濾布は、通気性が高すぎたため使用しなかった。
【００８５】
（ｅ）寸法変化現象
上記の条件で得られた濾布の使用前の寸法を測り、使用開始から９ヶ月目または１２ヶ月目に取り出して寸法を測り、使用前後での寸法変化の有無を調べた。
【００８６】
（ｆ）濾布交換の容易さ
使用開始から９ヶ月目または１２ヶ月目に濾布交換を行い、その容易さを調べた。
【００８７】
（ｇ）引張強力残存率（平均％）
ＪＩＳ Ｌ １０９６ ６．１２．１（１）Ａ法カットストリップ法に準じて、９ヶ月または１２ヶ月使用した各濾布から、幅５ｃｍおよび長さ３０ｃｍ（つかみ間隔２０ｃｍ）の試験片を５枚ずつ切り出し、定速伸長形引張試験機にて引張速度２０ｃｍ／分の条件で、各濾布から得られた各試験片の使用後の引張強力を測定して平均することにより、各濾布の使用後の引張強力とした。
【００８８】
得られた各濾布の使用後の引張強力の値と、各濾布に使用された各積層体の引張強力の値（上記項目（ａ）で得られた値）とを用いて、下式
【００８９】
【数３】

【００９０】
により、引張強力残存率（平均％）を求めた。
【００９１】
結果を表１および表２に示す。
【００９２】
【表１】

【００９３】
【表２】

【００９４】
さらに、上記実施例３および実施例５で得られた積層体ならびにそれを用いて上記のように作製された濾布について、以下の項目（ｈ）および（ｉ）の評価を行った。
【００９５】
（ｈ）粘着性ダスト防汚性
実施例３および実施例５で得られた積層体から、それぞれ５ｃｍ×５ｃｍの大きさの試験片を２枚ずつ切り出した。
【００９６】
まず、２０℃において、一方の試験片の表面を上方に向けて水平に置き、Ｂ重油を０．０３ｇ滴下した。３０秒後に吸い取り紙にて試験片表面に残っているＢ重油を吸い取り、その後の試験片表面の汚れ具合を、汚染グレースケールで判定し、常温防汚性を評価した。
【００９７】
さらに、濾布の使用条件下を想定して、もう一方の試験片を予め２６０℃に加熱しておき、上記の手順のうちのＢ重油滴下までを２６０℃で実施した。残りの手順は上記のように行い、高温防汚性を評価した。
【００９８】
上記評価は、汚染グレースケールが３級以上である場合を良好とし、３級未満の場合を不良とした。
【００９９】
（ｉ）目詰まりの有無および圧力損失
実施例３および実施例５で得られた積層体を用いて作製した濾布を、それぞれバグフィルター式集塵機（近藤設備設計社製、「密閉ボトムインレット」）に用いて、１２ヶ月使用したときの目詰まりおよび圧力損失について評価した。
【０１００】
圧力損失は、ＪＩＳ Ｂ ９９１０−１９７７に準拠して、集塵機の入口および出口ダクトにおける処理ガスの平均全圧の差を測定することにより評価した。
結果を表３に示す。
【０１０１】
【表３】

【０１０２】
表１および表２から明らかなように、所定の引張強力を有するポリイミドおよび／またはポリテトラフルオロエチレンから構成される基布の両面にポリイミドから構成されるウェブを有し、該基布と該ウェブとがニードルパンチで絡合しており、そして所定の引張強力、乾熱収縮率、通気性を有する積層体を用いて得られた実施例１〜５で得られた濾布は、比較例１〜４で得られた積層体を用いて作製された濾布に比べて、耐熱性、耐薬品性、および高温応力下での寸法安定性に優れ、フィルター交換し易く、かつ、長期間使用可能である。
【０１０３】
上記実施例１〜５で得られた濾布は、いずれも１２ヶ月間使用された時点で全く問題がないことが確認され、さらに継続して使用され得る。引張強力についても殆ど低下は見られない。
【０１０４】
比較例１で得られた積層体は、乾熱収縮率が大きく、熱応力もわずかに大きい。この積層体を用いて作製された濾布は、９ヶ月目にはリテーナーの浮き上がりが生じており、交換が必要であった。このとき、リテーナーとバグとの間の寸法的余裕が無くなっており、リテーナーからのバグの抜き取りは困難であった。
【０１０５】
比較例２で得られた積層体は、引張強力、乾熱収縮率、熱応力はいずれも本発明に用いられる範囲内であるが、通気性が大きすぎてダストの吹き漏れが懸念された。そのため、この積層体を用いて作製された濾布は使用し得なかった。
【０１０６】
比較例３の積層体は、乾熱収縮率のみが本発明に用いられる範囲を越えている。この積層体を用いて作製された濾布は、９ヶ月目には異常は発見されなかったが、１２ヶ月目には寸法変化の兆候が見られた。そして、濾布交換の際、リテーナーからの濾布の抜き取りが困難であった。
【０１０７】
比較例４の積層体は、乾熱収縮率および熱応力が本発明に用いられる範囲を越えている。この積層体を用いて作製された濾布は、９ヶ月目にはリテーナーの浮き上がりが発見され、交換が必要であった。そして濾布交換の際、リテーナーからの濾布の抜き取りが困難であった。
【０１０８】
さらに、表３から明らかなように、含フッ素ポリエーテル型ポリウレタンが撥水撥油剤として付与された本発明の積層体は特に、粘着性ダストの集塵を行う場合でも、常温（２０℃）および高温（２６０℃）のいずれにおいても防汚性に優れ、粘着性ダストによる目詰まりが生じにくく、圧力損失が低く長期間使用可能である。
【０１０９】
【発明の効果】
本発明の積層体は、耐熱性、耐薬品性、および強度のいずれにも優れるポリイミドおよび／または耐熱性と耐薬品性とに優れるポリテトラフルオロエチレンから構成され、所定の引張強力を有する基布の両面に、ポリイミドから構成されるウェブを有し、該基布と該ウェブがニードルパンチ絡合されているサンドイッチ状の構造と適切な表面状態とを有し、かつ、所定の引張強力、乾熱収縮率、および通気性を有する。従って、微細なダストも濾過され得（濾過機能が大きく）、かつ、高温応力下、酸性雰囲気下などの厳しい条件下でも、ポリイミドの有する特性が十分に発揮され、耐熱性、耐薬品性、および強度のいずれにも優れ、高温応力下での寸法変化が少ない。本発明の積層体は、通常、熱応力が所定の範囲にあるため、変形しにくい。本発明の積層体に撥水撥油剤が付与された場合には、常温および高温のいずれにおいても撥水撥油効果に優れ、さらに粘着性ダストによる汚染および目詰まりが起こりにくく、ダストの払い落としが容易である。
【０１１０】
従って、本発明の積層体を用いることにより、高温応力下、酸性条件下などの厳しい条件下での排ガス集塵においても集塵効率が高く、強度、耐熱性、および耐薬品性に優れると共に、寸法安定性および濾布交換時の作業性にも優れ、適度な通気性を有し、目詰まりしにくく、そして長期間使用可能なバグフィルター濾過集塵装置に用いられる濾布が提供される。
【０１１１】
特に、本発明の積層体を用いて得られた濾布をリテーナーに被せて使用する場合には、これらのウェブのうちのリテーナー側（内側）のウェブにより、基布が直接リテーナーに接触せず、濾過および高圧エアーによる払い落とし作業の繰り返しによる衝撃から保護されるため、基布の強度低下が防止され、その結果、濾布自体の強度の低下が防止される。
【０１１２】
さらに、本発明の積層体を用いることにより、通常、熱応力が小さく、リテーナー、スプリングなどのバグフィルター濾過集塵装置の他の部品に悪影響を与えない、バグフィルター濾過集塵装置用濾布が提供される。
【０１１３】
さらにまた、粘着性ダストの集塵が行われる場合に、本発明の積層体を用いることにより、常温および高温のいずれにおいても汚染されにくく、目詰まりしにくく、圧力損失が少ないバグフィルター濾過集塵装置用濾布が提供される。
【図面の簡単な説明】
【図１】 図１は、本発明の積層体の熱応力の測定チャートである。チャートの横軸は、測定開始後の経過時間を表し、左側の縦軸は応力を、右側の縦軸は温度を表す。図中の２本の曲線は、それぞれ時間の経過に伴う応力および温度の変化を表す。[0001]
BACKGROUND OF THE INVENTION
The present invention is a laminate suitably used for a filter cloth used in a bag filter for exhaust gas dust collection, particularly heat resistance, chemical resistance, dimensions under severe conditions such as high temperature stress and acidic conditions. The present invention relates to a laminate suitably used as a filter cloth excellent in both stability and strength.
[0002]
[Prior art]
SO generated during combustion of municipal waste, etc. in municipal waste incinerators, industrial waste incinerators, etc.₂, SO_Three, NO, NO₂, NO_Three, HCl, Cl₂Gases such as HF are harmful per se, and further include dust containing harmful substances such as dioxins. The exhaust gas dust collection performed to remove such dust is very important as an air pollution prevention measure. For exhaust gas dust collection, methods such as electrostatic dust collection and bag filter filtration dust collection are used. In particular, it is well known that dust collection by bag filter filtration is one of the best methods. Yes. Recently, the shift from the electrostatic dust collection method to the bag filter filtration dust collection method is conspicuous from the viewpoint of dioxin environmental index problems.
[0003]
In the bag filter filtration method, a filter cloth (filter bag) is used for collecting dust. Dust contained in the exhaust gas adheres to the filter cloth surface and is filtered. Dust adhering to and accumulating on the filter cloth is removed periodically or as needed to be removed, while the filter cloth is used repeatedly.
[0004]
As the dust removal method, for example, the filtration operation is temporarily stopped for each of the divided blocks, and the dust is removed by mechanical vibration or reverse airflow. There is a pulse jet method in which dust accumulated on the outside of the filter cloth is removed by instantaneously flowing high-pressure air into the inside while allowing gas to pass through and filtering. Of these, the pulse jet method is widely used recently as the most effective method for removing dust because it can continuously and rapidly remove dust.
[0005]
The filter cloth used in the bag filter filtration dust collector as described above is usually formed from various fibers and formed into a flat bag shape like a cylinder or envelope having a circular or elliptical cross section. In any shape, it is used in units of several tens to several hundreds per apparatus. Such a filter cloth has fine dust when used for exhaust gas dust collection in the above-mentioned municipal waste incinerators, industrial waste incinerators, etc., which are performed under severe conditions such as high temperature stress and acidic atmosphere. It is important that the dust collection function is large so that dust can be collected efficiently, and that the heat resistance and chemical resistance are excellent.
[0006]
By the way, the bag filter filtration dust collector uses a metal support called a birdcage-like retainer for smooth filtration and wiping work and for supporting the filter cloth. Some cloths are used. In this case, there is a problem that the filter cloth is easily damaged at the contact portion with the retainer due to repeated filtration and scraping operations. Bag filter filtration dust collector does not use the retainer as described above, and uses an internal filtration type bag filter that is used with the filter cloth tensioned by a spring so that it can respond to changes in length due to shrinkage of the filter cloth. There is also a filtration dust collector. In this case, there is a problem that when the filter cloth is used for a long time at a high temperature, the dimensional change of the filter cloth occurs, which causes the spring to stretch, breakage, or a state just before the breakage.
[0007]
Therefore, in recent years, a filter cloth having excellent heat resistance, chemical resistance, and dimensional stability, high strength, and high dust collection efficiency has been demanded even under severe conditions such as high temperature stress and acidic atmosphere.
[0008]
Conventionally, filter fabrics used at high temperatures are laminated base fabric and web using filter fabric materials such as meta-aramid fiber, polyphenylene sulfide (PPS) fiber, polyimide fiber, fluorine fiber, and glass fiber. And a method of entanglement using a needle punch; a laminate is formed by a method such as entanglement by a jet water flow, and the obtained laminate is formed into a predetermined shape.
[0009]
Of the fibers used as the conventional filter cloth material, meta-aramid fibers have low chemical resistance. For this reason, products with improved acid resistance by treatment with a fluorine-based resin or the like are commercially available, but there is a limit in terms of durability. PPS fibers are excellent in chemical resistance but slightly inferior in heat resistance and are not suitable for long-term use at high temperatures. Fluorine-based fibers are excellent in both heat resistance and chemical resistance, but their use is limited because they are insufficient in strength and very expensive. Since glass fiber is inferior in bending strength, it is not suitable for pulse jet type high-speed filtration in which continuous removal is performed.
[0010]
Furthermore, if the dust to be filtered contains a high proportion of oily or other sticky components, the releasability of dust from the filter cloth is insufficient, the dust removal efficiency is low, and Since the cloth is easily contaminated and clogged, there is a problem that a sufficient filtration effect cannot be obtained.
[0011]
In order to eliminate such problems, conventionally, a water- and oil-repellent agent is applied to the filter cloth obtained by using the above-mentioned fibers, and the surface of the filter cloth is a component of a water- and oil-repellent agent such as silicon or fluorine The method of improving the chemical resistance and dust releasability of the filter cloth, protecting the filter cloth material and changing the characteristics of the filter cloth surface has been taken, but sufficient effects have been obtained. Absent.
[0012]
Of the above filter cloth materials, polyimide fibers are excellent in all of heat resistance, chemical resistance, and strength, and are advantageous in terms of cost, and have recently been exclusively used as filter cloth materials. However, the polyimide fiber is characterized by an irregular cross section in which a Y-shaped cross section, an L-shaped cross section, a U-shaped cross section, etc. are mixed, has no melting point, and has a high glass transition point of 315 ° C. In the filter cloth, even if polyimide fibers are used, the original characteristics are not sufficiently exhibited.
[0013]
For example, a base fabric composed of polyimide fibers and a web composed of polyimide fibers are entangled using a needle punch to form a sheet-like laminate, and the obtained sheet-like laminate is made into a desired shape. In the filter cloth produced by the above method, the polyimide fiber itself is excellent in heat resistance. Therefore, even if it is used for a long time at a high temperature, the dimensional change and the strength reduction should hardly occur. However, in the case of a sheet-like laminate formed using a needle punch, the web occupying the majority is composed of a large number of curvilinear fibers that are intertwined in multiple directions. Dimensional changes are likely to occur due to enlargement or reduction. Therefore, a dimensional change is likely to occur also in a filter cloth obtained using such a laminate. Such a phenomenon is particularly prominent when stress is present at high temperatures. Furthermore, since the air permeability of the obtained laminate is too large and fine dust passes, there is a problem that dust collection efficiency is low and it is not suitable for a filter cloth.
[0014]
Furthermore, when a filter cloth obtained using a laminate composed of polyimide fibers is used in a bag jet filtration dust collector using a pulse jet continuous removal method, depending on the shape of the bag filter, the filter cloth may be used for a long time at a high temperature. If used, there will be no dimensional allowance between the filter cloth and the retainer, and it will be difficult to remove the retainer from the filter cloth during replacement, or the length of the filter cloth will shrink during use, causing the retainer to float. There is a problem.
[0015]
[Problems to be solved by the invention]
The present invention has been made to solve the above-described conventional problems, and the object thereof is excellent in heat resistance, chemical resistance, and dimensional stability even under high temperature stress and acidic atmosphere. An object of the present invention is to provide a laminate that is suitably used for manufacturing a filter cloth for a bag filter having high strength, moderate air permeability, and high dust collection efficiency.
[0016]
[Means for Solving the Problems]
The laminate of the present invention is a sheet-like laminate having webs on both sides of a base fabric, and the base fabric and the web being entangled, wherein the base fabric is polyimide and / or polytetrafluoroethylene The base fabric has a longitudinal tensile strength of 40 to 200 kgf / 5 cm width, the web is composed of polyimide fibers, and the laminate has a longitudinal tensile strength of 40 to 250 kgf / 5 cm width. And the dry heat shrinkage in the machine direction and the transverse direction are both 0.8% or less and 5-30 ml / cm²/ Sec breathability. This achieves the above object.
[0017]
In a preferred embodiment, the thermal stress is 10 kgf / 5 cm width or less.
[0018]
In a preferred embodiment, a water / oil repellent comprising a fluorine-containing ether type polyurethane is provided.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
The base fabric used in the present invention is preferably produced from polyimide and / or polytetrafluoroethylene. From the standpoint that the heat resistance and chemical resistance of the base fabric and the web are aligned at the same level, it is preferable to mainly use the same type of polyimide as the web described later. Polytetrafluoroethylene is also preferably used because of its excellent chemical resistance.
[0020]
The polyimide used in the present invention has the following general formula as disclosed in Japanese Patent Publication No. 63-27444.
[0021]
[Chemical 1]

[0022]
Is an aromatic polyimide that is extremely excellent in chemical resistance and dust releasability.
[0023]
Here, R in the above general formula is the general formula
[0024]
[Chemical formula 2]

[0025]
And a group represented by the general formula
[0026]
[Chemical Formula 3]

[0027]
It is group shown by these.
[0028]
The polyimide can usually be prepared by reacting benzophenone tetracarboxylic dianhydride, tolylene diisocyanate, and methylene diphenyl diisocyanate in an aprotic organic solvent.
[0029]
Such an aromatic polyimide is commercially available, for example, as a polyimide “P84” (registered trademark) from Lenzing AG.
[0030]
The polytetrafluoroethylene used in the present invention is conventionally known and has the following general formula:
[0031]
[Formula 4]

[0032]
Consists of units indicated by
[0033]
The polytetrafluoroethylene can be obtained, for example, by polymerizing tetrafluoroethylene under a pressure of 2200 to 1600 psi using a small amount of oxygen as a catalyst.
[0034]
The base fabric used in the present invention is a base fabric formed from fibers as long as the air permeability of the resulting laminate is not significantly impaired and the purpose of improving the strength and dimensional stability of the resulting laminate is achieved, It may be a film-shaped molded body, a molded body from slit yarn, a net-shaped molded body, or the like. From the viewpoint of damage to the needle punch used for entanglement, a base fabric formed from fibers is preferable.
[0035]
The base fabric used in the present invention is a monofilament yarn or multifilament formed from the above polyimide and polytetrafluoroethylene using polyimide fiber and polytetrafluoroethylene fiber formed by methods such as dry spinning and paste extraction, respectively. It can be suitably formed by weaving yarns alone or in combination into plain weaves, mocleno weaves, twill weaves and the like.
[0036]
The polyimide and / or polytetrafluoroethylene monofilament yarn or multifilament yarn used for forming the base fabric is in the range of 50 denier to 2000 denier, preferably 200 denier to 1500 denier, more preferably 300 denier to 1000 denier. Has fineness. When the fineness is less than 50 denier, the strength of the resulting laminate is inferior, and when it exceeds 2000 denier, the thickness may be too large.
[0037]
Although the density of the base fabric varies depending on the weaving method, when the base fabric is woven into a plain weave, the density is 10 to 100 / 5cm, preferably 16 to 80 / 5cm. If the density is less than 10 pieces / cm, the form is unstable, and if it exceeds 100 pieces / cm, there is a risk of poor air permeability. When the base fabric is woven in mocleno weave, the density is 16 to 100 pieces / 5 cm, preferably 20 to 80 pieces / cm. If the density is less than 16/5 cm, the form is unstable, and if it exceeds 100 / cm, there is a risk of poor air permeability.
[0038]
The base fabric has a longitudinal tensile strength of 40 to 200 kgf / 5 cm width, preferably 50 to 120 kgf / 5 cm width, and more preferably 60 to 110 kgf / 5 cm width. When the tensile strength in the longitudinal direction is less than 40 kgf / 5 cm width, the longitudinal tensile strength of the laminate formed by laminating webs described later and preferably entangled with the needle punch is less than 40 kgf / 5 cm width. As a result, if it is used as a filter cloth for a bag filter, there is a risk of breakage or perforation in a short time. On the contrary, if the tensile strength in the longitudinal direction exceeds 200 kgf / 5 cm width, there is no problem in strength, but the quality becomes excessive, and moreover, a base fabric constituent material such as the above fiber is used in an excessive amount. Therefore, it is not preferable in terms of cost.
[0039]
Here, the above “tensile strength” means that the width of the test piece is 5 cm and the grip interval is 20 cm in a constant speed extension type tensile tester according to JIS L 1096 6.12.1 (1) A method cut strip method. It is a characteristic measured at a tensile speed of 20 cm / min.
[0040]
The web used in the present invention is composed of fibers made of polyimide.
[0041]
As said polyimide, the thing similar to the polyimide used for the said base fabric is used.
[0042]
The polyimide is processed into polyimide fiber staples by further subjecting a polyimide single yarn fiber produced by a known method to normal crimping and cutting steps.
[0043]
The polyimide fiber used in the present invention has a fineness of 0.4 to 6 denier, preferably 0.6 to 4 denier, and 30 mm to 200 mm, preferably 40 mm to 120 mm, from the viewpoint of increasing the surface area and improving the filtration function. It is preferable to have a fiber length of If the fineness is less than 0.4 denier, the strength is insufficient, and if it exceeds 6 denier, there is a risk of poor air permeability. If the fiber length is less than 30 mm, entanglement will be insufficient, and if it exceeds 200 mm, there is a risk of poor opening.
[0044]
The web used in the present invention has a basis weight of 50 g / m from the polyimide fiber.²~ 800g / m², Preferably 300 g / m²~ 700g / m²Thus, it can be produced by a method such as blending, opening, and carding. The basis weight is 50 g / m²The air permeability is too large at less than 800 g / m.²Exceeding this may result in poor ventilation.
[0045]
In the laminate of the present invention, the web made of the polyimide fiber is laminated on both sides of the base fabric, and then the fibers between the web and the base fabric are entangled by, for example, a normal needle punch, a jet water flow or the like. To obtain. The needle punch method is preferable because the degree of entanglement is high. Further, if necessary, heat treatment is performed at a high temperature of 250 ° C. to 310 ° C. for 0.5 minutes to 5 minutes, the surface is gas-fried, and heated to a hot roll having a surface temperature of 200 ° C. to 300 ° C. The pressing is performed by applying a pressure of 5 kg / cm to 30 kg / cm. Therefore, the laminate of the present invention has a sandwich-like structure in which a base fabric is sandwiched between webs.
[0046]
The dry heat shrinkage rate of the laminate of the present invention is 0.8% or less, preferably 0.6% or less, more preferably 0.4 in both the vertical direction (long direction) and the horizontal direction (short direction). % Or less. If the dry heat shrinkage rate exceeds 0.8%, it will be difficult to remove the retainer from the bug when replacing the bug due to lack of dimensional margin with the retainer as the support due to long-term use at high temperatures. The problem is that the retainer is lifted by the contraction of the bug length during use.
[0047]
Here, the above “dry heat shrinkage” refers to the rate of change in the dimensions of the laminate before and after the heat treatment of the laminate at 240 ° C. for 1 hour.
[0048]
[Expression 1]

[0049]
It is calculated by.
[0050]
The laminate is also 5-30 ml / cm²/ Sec, preferably 5-15 ml / cm²/ Sec, more preferably 7 to 13 ml / cm²/ Sec breathability. Breathability is 5ml / cm²If it is less than / sec, an excellent dust collection effect can be obtained temporarily at the beginning of use of the filter cloth obtained by using such a laminate, but the filter cloth can be clogged in a short time and used. Disappear. Breathability is 30ml / cm²If it exceeds / sec, fine dust passes through the filter cloth, so that a desired dust collection effect cannot be obtained.
[0051]
Here, the above “breathability” is a characteristic measured by a Frazier type tester according to JIS-L-1096-6.27.1A method.
[0052]
The laminate preferably has a thermal stress of 10 kgf / 5 cm width or less, more preferably 9 kgf / 5 cm width or less, particularly preferably 8 kgf / 5 cm width or less. When the thermal stress exceeds 10 kgf / 5 cm width, the retainer may be lifted even if the dry heat shrinkage rate at 240 ° C. × 1 hour is 0.8% or less, which is not preferable. In particular, when the thermal stress is extremely large, a filter cloth obtained using this laminate may bend the retainer. Such a phenomenon occurs depending on the design of the bug filter. For example, when there is no allowance in the dimension difference between the filter cloth and the retainer, or when the retainer is easily lifted by the contraction of the filter cloth and the thermal stress generated in the filter cloth exceeds the force for fixing the retainer, The above phenomenon occurs. Furthermore, in an internal surface filtration type bag filter filtration dust collector that is used in a state in which the filter cloth is tensioned by a spring so as to be able to cope with a change in length due to contraction of the filter cloth without using a retainer, the thermal stress is 10 kgf / If the width exceeds 5 cm, the spring may be stretched, or may be damaged or on the verge of being damaged.
[0053]
Here, the “thermal stress” is a stress generated when the laminate of the present invention once expands and then cools and contracts.
[0054]
The above-mentioned thermal stress is applied to a strip-shaped test piece of a laminate, when an initial load of 2 kgf / 5 cm width is applied, both ends are fixed to a clamp of a tensile tester, heated at 260 ° C. for 1 hour, and then exposed to room temperature. The generated stress is measured as follows and expressed as a numerical value.
[0055]
A test piece having a width of 5 cm and a length of 30 cm (grip interval 20 cm) cut out from the laminate is held at both ends in the longitudinal direction, and an initial load of 2 kgf / 5 cm width is applied. As a procedure at this time, one end of the test piece is fixed to the clamp of the tensile tester, and then the initial load is applied, and the other end is fixed to the other clamp in that state, or both ends of the test piece are used. After fixing to the respective clamps, a method of applying the initial load by moving the clamps can be used. In either case, after applying a predetermined initial load, the clamps holding the test piece are not moved until the measurement is completed, and the test piece is heated to 260 ° C. for 1 hour and then exposed to room temperature. On the chart. In the present invention, the thermal stress in the longitudinal direction is measured and used as a representative value of the sample. The value of the initial load used in this measurement is very large as compared with the case of normal tensile strength measurement, etc., in order to make it easier to determine the magnitude of the measured thermal stress.
[0056]
An example of a stress measurement chart of the laminate of the present invention is shown in FIG. FIG. 1 is a chart in which changes in temperature and stress are plotted against time. In the measurement method described above, the stress increases from the point of time when the heating at 260 ° C. is stopped for 1 hour, and then becomes flat in about 3 and a half hours to 4 hours, and then gradually decreases. The point at which the stress leveled out, that is, the highest point, is read as thermal stress and used as the measured value.
[0057]
When the laminate of the present invention is used for a filter cloth used for dust containing an adhesive component such as dust having a high oil component content, it is preferable that the water repellent is formed on both surfaces thereof. An oil repellent may be applied. This prevents dust adhesive components from accumulating on the surface of the filter cloth, preventing clogging and facilitating peeling of the adhesive dust.
[0058]
As the water / oil repellent, fluorine-containing ether type polyurethane, fluorine-containing urethane oligomer, fluorine-containing polyacrylate, polytetrafluoroethylene, dimethylsiloxane-based silicon, amino-modified siloxane-based silicon, epoxy-modified siloxane-based silicon and the like are preferably used. Can be. From the viewpoint of water and oil repellency at high temperature use, fluorine-containing ether type polyurethane is most preferable.
[0059]
As a method for applying the water / oil repellent, the laminate is dipped in a water / oil repellent solution, and then pulled up and squeezed with a mangle; the water / oil repellent solution is coated on the surface of the laminate and dried. Method: A conventionally known method such as a method of foaming a solution of a water / oil repellent agent, coating the surface of the laminate and drying the solution can be used.
[0060]
The application amount of the water / oil repellent is preferably in the range of 0.5 to 10 parts by weight, more preferably 1 to 5 parts by weight with respect to 100 parts by weight of the laminate. If the applied amount is less than 0.5 parts by weight, the desired adhesive dust releasability cannot be obtained, and if it exceeds 10 parts by weight, there is a risk of poor air permeability.
[0061]
The operation of the present invention will be described below.
[0062]
The laminate of the present invention is composed of polyimide having excellent heat resistance, chemical resistance, and strength and / or polytetrafluoroethylene having excellent heat resistance and chemical resistance, and has a predetermined tensile strength. A sandwich-like structure in which the web and the web are intertwined with the base fabric, and a surface state that has been densified and treated by gas hair roasting or the like. And has a predetermined tensile strength, dry heat shrinkage, and air permeability. Therefore, even fine dust can be filtered (that is, the filtration function is large), and even under severe conditions such as high-temperature stress and acidic atmosphere, the characteristics of polyimide are fully exhibited, and heat resistance and chemical resistance And strength are both excellent, and there is little dimensional change under high temperature stress.
[0063]
Since the laminated body of the present invention usually has a thermal stress in a predetermined range, it is difficult to deform.
[0064]
When a water- and oil-repellent agent is applied to the laminate of the present invention, the water- and oil-repellent effect is excellent at both normal temperature and high temperature, and contamination and clogging due to sticky dust hardly occur. Is easy.
[0065]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention in more detail, this invention is not limited to these.
[0066]
(Example 1)
Using a 960 denier polyimide multifilament yarn, a plain fabric with a density of 30 / 5cm and 22 / 5cm was woven. The tensile strength of the obtained plain woven fabric was 91 kgf / 5 cm in length and 77 kgf / 5 cm in width. This plain woven fabric is used as a base fabric, and webs made of polyimide staples with 2 denier x 60 mm fiber length are laminated on both sides, then entangled by needle punching, heat treated at a high temperature of 280 ° C. for 3 minutes, and the surface is treated with gas hair By baking and pressing with a hot roll having a surface temperature of 200 ° C. under a pressure of 20 kg / cm, the basis weight is 512 g / m.²And the laminated body of thickness 2.0mm was obtained.
[0067]
(Example 2)
Using the same polyimide multifilament yarn as in Example 1, weaving a plain fabric with a density of 25 / 5cm and 20 / 5cm in width, using this plain fabric as a base fabric, 2 denier x 60mm fiber length on both sides After laminating webs made of polyimide staples, they are entangled by needle punching, heat treated for 3 minutes at a high temperature of 300 ° C., gas-fried on the surface, and 20 kg / cm in a hot roll with a surface temperature of 250 ° C. By pressing under pressure, the basis weight is 508 g / m.²And the laminated body of thickness 1.9mm was obtained.
[0068]
(Example 3)
The same fabric as the plain weave woven in Example 2 was used as a base fabric, and a web of 2 denier × 60 mm fiber length polyimide staples was laminated on both sides, and then a needle punch was applied and entangled to obtain a laminate. . Next, the obtained laminate was dipped in a water / oil repellent composed of a fluorine-containing ether type polyurethane, then pulled up, squeezed with a mangle and dried to give a water / oil repellent. Furthermore, after heat-treating this laminated body at a high temperature of 300 ° C. for 3 minutes, the surface was burned with a gas and pressed with a hot roll having a surface temperature of 250 ° C. under a pressure of 20 kg / cm. m²And the laminated body of thickness 2.1mm was obtained.
[0069]
(Example 4)
A 400-denier polytetrafluoroethylene (PTFE) monofilament yarn was used to weave a mocleno fabric having a density of 60 / 5cm in length and 60 / 5cm in width. The finished fabric had a tensile strength of 75 kgf / 5 cm in length and 76 kgf / 5 cm in width. Using this mocleno woven fabric as a base fabric, a web of 2 denier x 60 mm fiber length polyimide staples is laminated on both sides, needle punched, ripened at a high temperature of 280 ° C. for 3 minutes, and then the surface is baked with gas hair. A 20 kg / cm pressure is applied with a hot roll at a temperature of 200 ° C., and the weight is 517 g / m.²And the laminated body of thickness 1.9mm was obtained.
[0070]
(Example 5)
The basis weight is 499 g / m in the same manner as in Example 3 except that fluorine-containing polyacrylate is used as the water and oil repellent.²And the laminated body of thickness 2.1mm was obtained.
[0071]
(Comparative Example 1)
Using a 960 denier polyimide multifilament yarn, a plain woven fabric with a density of 30 length / 5 cm and a width of 22/5 cm was woven. The tensile strength of the finished plain fabric was 93 kgf / 5 cm in length and 78 kgf / 5 cm in width. Using this plain woven fabric as a base fabric, a web made of polyimide staple of 2 denier x 60 mm fiber length is laminated on both sides, needle punched, heat treated for 3 minutes at a temperature of 250 ° C., then the surface is gas-fried, and the surface temperature Pressed with a heat roll of 200 ° C. under a pressure of 20 kg / cm, the basis weight is 520 g / m.²And the laminated body of thickness 2.2mm was obtained.
[0072]
(Comparative Example 2)
A base material is a polyimide plain woven fabric having a density of 25/5 cm in length and 20/5 cm in width as in Example 2, and a web made of polyimide staples of 2 denier × 60 mm fiber length is laminated on both sides and needle punched, 300 After heat treatment at a temperature of 3 ° C. for 3 minutes, the surface is burned with gas, pressed with a hot roll with a surface temperature of 200 ° C. under a pressure of 5 kg / cm, and a basis weight of 495 g / m²And the laminated body of thickness 2.4mm was obtained.
[0073]
(Comparative Example 3)
A plain woven fabric having a density of 50 / 5cm in length and 40 / 5cm in width was woven using a 450 denier polyimide multifilament yarn. The tensile strength of the finished plain fabric was 71 kgf / 5 cm in length and 68 kgf / 5 cm in width. Using this plain woven fabric as a base fabric, a web of polyimide staples with 2 denier x 60 mm fiber length is laminated on both sides, needle punched, heat-treated at 300 ° C for 3 minutes, and then the surface is gas-fried to obtain a surface temperature. Pressed with a heat roll of 250 ° C. under a pressure of 20 kg / cm, weight per unit of 509 g / m²And the laminated body of thickness 1.9mm was obtained.
[0074]
(Comparative Example 4)
A web made of polyimide staples of 2 denier x 60 mm fiber length on both sides of a plain fabric with a length of 60 / 5cm and a width of 46 / 5cm using the same polyimide multifilament yarn as in Comparative Example 3. After laminating and needle punching, the surface was burned with gas, and then pressed with a hot roll with a surface temperature of 250 ° C. under a pressure of 20 kg / cm, and the basis weight was 517 g / m.²And the laminated body of thickness 2.2mm was obtained.
[0075]
Evaluation of laminate
The following items (a) to (d) were evaluated using the respective laminates obtained in the above Examples and Comparative Examples.
[0076]
(A) Tensile strength
In accordance with JIS L 1096 6.12.1 (1) Method A cut strip method, a test piece having a width of 5 cm and a length of 30 cm (grip interval 20 cm) cut out from each of the laminates obtained in the above examples and comparative examples. Was measured at a tensile speed of 20 cm / min with a constant speed extension type tensile tester to evaluate the tensile strength.
[0077]
(B) Dry heat shrinkage
A test piece having a width of 30 cm and a length of 30 cm was cut out from each of the laminates obtained in the above examples and comparative examples. The test piece thus obtained was written with a standard line of 25 cm in length and 5 in each direction, and then the length was measured accurately, heated at 240 ° C. for 1 hour using an air circulation oven, and then 20 ° C. , After standing to cool at a relative humidity of 65%, measure the length of each standard wire.
[0078]
[Expression 2]

[0079]
Thus, the dry heat shrinkage was obtained and averaged.
[0080]
(C) Breathability
In accordance with JIS-L-1096-6.27.1A method, air permeability was evaluated by measuring each laminate obtained in the above Examples and Comparative Examples with a Frazier type tester.
[0081]
(D) Thermal stress
The laminates obtained in the above examples and comparative examples were cut out to a width of 5 cm and a length of 30 cm, respectively, to obtain test pieces. At this time, the length was taken in the long direction. One end of the obtained test piece was fixed to a clamp of a tensile tester, and the other end was fixed to the other clamp in a state where an initial load of 2 kgf / 5 cm width was applied. After the prescribed initial load is applied, the clamps holding the specimen are not moved until the measurement is completed. While recording the temperature, the test piece in this state was heated at 260 ° C. for 1 hour, then exposed to room temperature, the longitudinal stress generated from the test piece was recorded, and the maximum stress on the obtained chart was the thermal stress value. I read as.
[0082]
Evaluation of filter cloth
Furthermore, using each laminate obtained in the above Examples and Comparative Examples, a filter cloth (diameter) for a bag filter filtration dust collector (“closed bottom inlet” manufactured by NKK) used in a municipal waste incinerator. 164 mm × 5200 mm long bag type). All the filter cloths other than the filter cloth obtained in Comparative Example 2 started to be used at the same time and used under the same conditions. The following items (e) to (g) were evaluated once in the 9th month. The filter cloth in which the dimensional change was recognized was replaced. The filter cloth in which no dimensional change was observed at this time was used as it was, and the above items were evaluated at 12 months.
[0083]
The target gas for dust collection by the filter cloth has a temperature of 230 ° C. to 240 ° C., a moisture content of 5% to 30%, and an HCl concentration of 300 mg / Nm.^Three, SO_xConcentration is 120ppm, NO_xThe concentration was 100 ppm and the apparent filtration rate was 1.2 m / min.
[0084]
The filter cloth obtained in Comparative Example 2 was not used because the air permeability was too high.
[0085]
(E) Dimensional change phenomenon
The filter cloth obtained under the above conditions was measured for dimensions before use, taken out at the ninth or twelfth month from the start of use, measured for dimensions, and examined for dimensional changes before and after use.
[0086]
(F) Ease of filter cloth replacement
The filter cloth was changed in the 9th or 12th month from the start of use, and the ease of the change was examined.
[0087]
(G) Tensile strength remaining rate (average%)
According to JIS L 1096 6.12.1 (1) Method A cut strip method, 5 test pieces each having a width of 5 cm and a length of 30 cm (grip spacing 20 cm) from each filter cloth used for 9 months or 12 months Using each filter cloth by measuring and averaging the tensile strength after use of each test piece obtained from each filter cloth under the condition of a cut speed and a constant speed extension type tensile tester at a tensile speed of 20 cm / min. Later tensile strength was used.
[0088]
Using the value of tensile strength after use of each obtained filter cloth and the value of tensile strength of each laminate used for each filter cloth (value obtained in the above item (a)), the following formula
[0089]
[Equation 3]

[0090]
Thus, the residual tensile strength ratio (average%) was determined.
[0091]
The results are shown in Tables 1 and 2.
[0092]
[Table 1]

[0093]
[Table 2]

[0094]
Furthermore, the following items (h) and (i) were evaluated for the laminates obtained in Example 3 and Example 5 and the filter cloths produced as described above using the laminates.
[0095]
(H) Adhesive dust antifouling property
Two test pieces each having a size of 5 cm × 5 cm were cut out from the laminates obtained in Example 3 and Example 5.
[0096]
First, at 20 ° C., one test piece was placed horizontally with the surface facing upward, and 0.03 g of B heavy oil was dropped. After 30 seconds, the B heavy oil remaining on the surface of the test piece was blotted with a blotting paper, and the degree of soiling on the surface of the test piece thereafter was judged by a contaminated gray scale, and the room temperature antifouling property was evaluated.
[0097]
Further, assuming the use condition of the filter cloth, the other test piece was heated to 260 ° C. in advance, and the above procedure until the dropping of B heavy oil was performed at 260 ° C. The rest of the procedure was performed as described above to evaluate high temperature antifouling properties.
[0098]
In the above evaluation, the case where the contaminated gray scale was grade 3 or higher was judged good, and the case where it was less than grade 3 was judged poor.
[0099]
(I) Clogging and pressure loss
When the filter cloth produced using the laminate obtained in Example 3 and Example 5 is used for 12 months using a bag filter type dust collector (Kondo Equipment Design Co., Ltd., “sealed bottom inlet”), respectively. Clogging and pressure loss were evaluated.
[0100]
The pressure loss was evaluated by measuring the difference in average total pressure of the processing gas at the inlet and outlet ducts of the dust collector in accordance with JIS B 9910-1977.
The results are shown in Table 3.
[0101]
[Table 3]

[0102]
As is clear from Tables 1 and 2, the base fabric and the web have a web composed of polyimide on both sides of a base fabric composed of polyimide and / or polytetrafluoroethylene having a predetermined tensile strength. And the filter cloth obtained in Examples 1 to 5 obtained using a laminate having a predetermined tensile strength, dry heat shrinkage rate and air permeability. Compared with the filter cloth made using the laminate obtained in ~ 4, it has excellent heat resistance, chemical resistance, and dimensional stability under high temperature stress, easy to replace the filter, and can be used for a long time It is.
[0103]
Any of the filter cloths obtained in Examples 1 to 5 was confirmed to have no problem when used for 12 months, and can be used continuously. There is almost no decrease in tensile strength.
[0104]
The laminate obtained in Comparative Example 1 has a large dry heat shrinkage and a slightly large thermal stress. The filter cloth produced using this laminate had raised the retainer in the ninth month and needed to be replaced. At this time, there was no dimensional margin between the retainer and the bug, and it was difficult to remove the bug from the retainer.
[0105]
The laminate obtained in Comparative Example 2 had all of the tensile strength, the dry heat shrinkage, and the thermal stress within the range used in the present invention, but the air permeability was too high, and there was a concern about dust leakage. Therefore, the filter cloth produced using this laminate cannot be used.
[0106]
In the laminate of Comparative Example 3, only the dry heat shrinkage exceeds the range used in the present invention. No abnormality was found in the filter cloth produced using this laminate in the 9th month, but there was an indication of dimensional change in the 12th month. And, when replacing the filter cloth, it was difficult to remove the filter cloth from the retainer.
[0107]
The laminate of Comparative Example 4 has a dry heat shrinkage rate and thermal stress that exceed the ranges used in the present invention. The filter cloth produced using this laminate was found to have lifted retainers in the 9th month and needed to be replaced. When replacing the filter cloth, it was difficult to remove the filter cloth from the retainer.
[0108]
Further, as is apparent from Table 3, the laminate of the present invention to which the fluorine-containing polyether type polyurethane is applied as a water and oil repellent, particularly at the time of collecting dust of sticky dust at room temperature (20 ° C.) and It is excellent in antifouling property at any high temperature (260 ° C.), hardly clogged with adhesive dust, has a low pressure loss and can be used for a long time.
[0109]
【The invention's effect】
The laminate of the present invention is composed of polyimide having excellent heat resistance, chemical resistance, and strength and / or polytetrafluoroethylene having excellent heat resistance and chemical resistance, and has a predetermined tensile strength. A web composed of polyimide on both sides, a sandwich-like structure in which the base fabric and the web are entangled with a needle punch, and an appropriate surface state, and a predetermined tensile strength, dryness It has heat shrinkage rate and air permeability. Therefore, even fine dust can be filtered (the filtration function is large), and the characteristics of polyimide are fully exhibited even under severe conditions such as high temperature stress and acidic atmosphere, and heat resistance, chemical resistance, and Excellent in both strengths and little dimensional change under high temperature stress. Since the laminated body of the present invention usually has a thermal stress in a predetermined range, it is difficult to deform. When a water- and oil-repellent agent is applied to the laminate of the present invention, the water- and oil-repellent effect is excellent at both normal temperature and high temperature. Is easy.
[0110]
Therefore, by using the laminate of the present invention, dust collection efficiency is high even in exhaust gas dust collection under severe conditions such as high temperature stress and acidic conditions, and excellent in strength, heat resistance, and chemical resistance, Provided is a filter cloth used for a bag filter dust collector that is excellent in dimensional stability and workability at the time of filter cloth replacement, has moderate air permeability, is not easily clogged, and can be used for a long period of time.
[0111]
In particular, when the filter cloth obtained using the laminate of the present invention is used by covering the retainer, the base cloth does not directly contact the retainer by the retainer side (inner side) web of these webs. Further, since it is protected from the impact caused by repeated filtration and high-pressure air removal work, the strength of the base fabric is prevented from being lowered.
[0112]
Further, by using the laminate of the present invention, a filter cloth for a bag filter filtration dust collector that usually has low thermal stress and does not adversely affect other parts of the bag filter filtration dust collector such as a retainer and a spring is provided. Provided.
[0113]
In addition, when sticky dust is collected, by using the laminate of the present invention, bag filter filtration dust collection is less likely to be clogged, clogged, and low in pressure loss at both normal and high temperatures. An apparatus filter cloth is provided.
[Brief description of the drawings]
FIG. 1 is a measurement chart of thermal stress of a laminate of the present invention. The horizontal axis of the chart represents the elapsed time after the start of measurement, the left vertical axis represents stress, and the right vertical axis represents temperature. The two curves in the figure represent changes in stress and temperature over time, respectively.

Claims (3)

A sheet-like laminate having webs on both sides of a base fabric and intertwined with the base fabric and the web,
The base fabric is composed of polyimide and / or polytetrafluoroethylene,
The tensile strength in the longitudinal direction of the base fabric is 40 to 200 kgf / 5 cm width,
The web is composed of polyimide fibers ;
The laminate has a tensile strength in the machine direction of 40 to 250 kgf / 5 cm, and the dry heat shrinkage in the machine direction and transverse direction when the laminate is dry-heated at 240 ° C. for 1 hour is 0.8% or less. , and the passing temper Ri 5~30ml / cm ² / sec der, and thermal stress is 10 kgf / 5 cm width or less, laminate.   The laminate according to claim 1, wherein a water- and oil-repellent agent comprising a fluorine-containing ether type polyurethane is applied. The laminated body for bag filters of Claim 1 or 2.

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