JP4065374B2

JP4065374B2 - Waterproof tape for cable

Info

Publication number: JP4065374B2
Application number: JP2001333140A
Authority: JP
Inventors: 茂直小柳
Original assignee: FUKUOKA CLOTH INDUSTRY CO., LTD.
Current assignee: FUKUOKA CLOTH INDUSTRY CO., LTD.
Priority date: 2001-10-30
Filing date: 2001-10-30
Publication date: 2008-03-26
Anticipated expiration: 2021-10-30
Also published as: JP2003141939A

Description

【０００１】
【産業上の利用分野】
本発明は、電力ケーブルの外被の破損時に放射状と長さ方向への水の浸入と移動を防止するためにケーブル内に捲回して使用される止水テープに関する。
【０００２】
【従来の技術】
本願出願人は、先に、特許第３２１２２５１号において、コルゲート金属外装溝及び隙間の走水を更に確実に防止できる二種類の止水テープを用いた超高圧コルゲート金属電力ケーブルを開示した。
【０００３】
この止水テープは、銅線が長さ方向に数本織り込まれた織物基材の両面に吸水性半導電ゴム組成物を含浸し銅線が表面に露出している第１のテープと、厚手織物の基材の片面に半導電性ゴム組成物を塗布し、他面に吸水性半導電ゴム組成物を塗布し、吸水性半導電ゴム組成物の塗布層上に低目付不織布カバー材を貼り合わした第２のテープの組合せからなり、それぞれのテープを金属コルゲート外装ケーブルの押出外部半導電層上（金属コルゲート下）に合わせ巻きして使用される。
【０００４】
これによって、いずれのテープも、押出外部半導電層と金属コルゲート外装との間に吸水面を外側に向けて合わせ巻きされるので、金属コルゲート外装が破損して水がケーブル内に侵入すると両テープが同時に吸水して膨潤する。そして、前記第２のテープの低目付不織布カバー材は、外部から水分が浸入した際には、その箇所が吸水性ゴム組成物の膨潤したゲル状物を溜める膨潤ダムとして作用し、吸水性ゴム組成物の膨潤したゲル状物が水圧で押し流されることを妨げ、短い距離で走水を防止する機能を有する。
【０００５】
これによって上記特許に開示された止水テープは、非常に大きな隙間空間を有する金属コルゲート部分のその止水能において極めて優れた止水効果を発揮する。
【０００６】
なお、二枚の半導電性又は絶縁性布帛間にサンドイッチされた半導電性又は絶縁性吸水層よりなる一般的なケーブル用止水テープの膨潤面の少なく共一枚の布帛として、前記金属コルゲート電力ケーブル等に使用されているような繊維間間隙（目隙）が比較的少ない低目付不織布カバー材と、特開平３−２２４７２９号や特開平５−９２５２５号に開示されているような目隙が大きい特殊不織布カバー材の二種類が使用されている。
【０００７】
【発明が解決しようとする課題】
ところが、最近、金属コルゲート電力ケーブルにおいて、この種の止水テープのコスト面からの検討が行われるようになり、とくに、前記の第１のテープの銅線が長さ方向に数本織り込まれた織物基材の両面への吸水性半導電ゴム組成物の含浸処理に手間と時間を要するのがコスト低減の阻害要因であることが問題点として指摘されるようになった。
【０００８】
そこで、テープ自体のコスト低減のために、第１のテープの銅線が長さ方向に数本織り込まれた織物基材の両面への吸水性半導電ゴム組成物の含浸処理を省略し、第２のテープによる膨潤ダムとしての作用による防水機能に頼る方式が検討されるようになり、これによるコスト低減を図ることが試みられるようになった。
【０００９】
ところが、この第１のテープへの吸水性半導電ゴム組成物の削減による吸水能の大幅な低下によって、全体としての止水機能を維持するためには、第２のテープによる膨潤ダムの止水機能を大幅に高める必要が生じる。
【００１０】
この第２のテープは、目隙が比較的小さな布帛がカバー材として使用されているため、前記電力ケーブルの金属コルゲート外装が破損時に水と接触しても、半導電性吸水層中の膨潤吸水性樹脂粉末がカバー材を貫通してカバー材の表面に露出することは殆どなく、表面に露出していない膨潤吸水性樹脂が蓄積されるいわゆる「膨潤ダム」を形成し、これによって止水効果を発揮する機能を有する。
【００１１】
ところが、第２のテープの機能は、金属コルゲート電力ケーブルの半導電性層の上に第１のテープと合わせ巻きして使用される際、押出半導電性層上に張力下で巻き付けられるため、第２のテープのカバー材が引張られた状態で捲回された状態にあり、その結果止水テープのカバー材が止水テープの吸水層の膨潤能力を著しく阻害しているという知見を得た。
【００１２】
すなわち、カバー材は、吸水性樹脂粉末が基材布帛上に付着される場合、基材とカバー材としての布帛間に吸水性樹脂粉末を挟持して吸水性樹脂粉末の脱落を防止する。しかしながら、実際には、ケーブル用止水テープはケーブル内の使用部位に螺旋状に引張った状態で或いは螺旋状に重ね合わせて、又は長さ方向に折り重ねて巻き付けられており、全体的又は部分的に止水テープのカバー材全体や耳部が張力下又は重ね合わせにより拘束された状態にあり、カバー材が、水と接触した際、吸水性樹脂粉末の膨潤を抑制し、導電性又は絶縁性吸水層の吸水能力を著しく阻害している。従って、前記の第２のテープにおいて、高吸水性樹脂粉末の付着量を増加して吸水能を増加させても、実用上ケーブル捲回後は殆ど止水能の向上に寄与しないことも判明した。
【００１３】
一方、少なくとも一枚の布帛としての目隙が大きな特殊不織布カバー材は、製法が特殊で複雑なため高価であるが、吸水層の吸水性樹脂粉末の粒子径に関して、小さな粒子径の粉末が使用される場合、水と接触した際、吸水性樹脂粉末が目隙を貫通してカバー材上に露出するという長所を持っている。しかしながら、このように目隙が大きなカバー材を前記金属コルゲート電力ケーブルに使用すると止水テープのカバー材表面から吸水性樹脂粉末が露出するため、ケーブルの止水試験時露出した膨潤粉末が水圧により押し流され、その止水能を発揮できず、このように大きな隙間空間部位には使用できないという欠陥がある。更に、最近、走水防止型電力ケーブルの用途拡大と共にケーブルの止水試験に使用される水頭圧が従来の１ｍ高さから数１０ｍへと徐々に増加されており、目隙が大きな特殊不織布カバー材では、水と接触時カバー材を貫通してカバー材表面上に膨潤吸水性粉末が露出すると、水圧によって粉末が益々押し流されてしまい止水能を発揮できず、海底ケーブルのように高水圧が適用されるケーブルにも使用できない。
【００１４】
本発明は、二枚の半導電性布帛の間にサンドイッチされた半導電性吸水層からなるケーブル用止水テープにおいて、少なくとも一枚の半導電性カバー材布帛の改良によって、金属コルゲートケーブル部位のような大きな隙間は勿論、高水圧が適用される海底ケーブルにも使用できる優れた止水能を有するケーブル用止水テープを提供する。
【００１５】
【課題を解決するための手段】
本願発明は、このような従来の比較的小さな目隙の低目付不織布や目隙の大きな特殊不織布をカバー材として使用した止水テープの止水能には限界があり、ケーブル外装の破損よる浸入水による吸水層に含まれる吸水性組成物のゲル化による膨潤吸水層がカバー材の箇所に貯蔵されるダム作用を、より機能させることによって達成でき、そのためには、カバー材の伸張特性を管理することによって止水テープの止水能の向上が可能であるという知見の下で完成した。
【００１６】
すなわち、本願発明に係るカバー材布帛の特性として、カバー材該当布帛の長さ方向に対して４５°の角度で採取した試料の５％モジュラスが、５０ｍｍ幅当たり、０．２００ｋｇまでは効果的な前記「膨潤ダム」による機能を発揮でき、このモジュラスの値は小さい程良い。すなわち、本発明の止水テープは、低いモジュラス特性を有する低モジュラス布帛と呼ぶるカバー材の使用によって、ゲル化した吸水性組成物の「膨潤ダム」による機能による止水機能を発揮させるものである。
【００１７】
一般には、５％モジュラス値は、材質の低荷重付与時の伸びやすさ又は柔軟性の尺度を指す。本発明の場合は、水との接触によって吸水性樹脂粉末が膨潤する際、止水テープが引張って突合せで又は部分的に重ね合わせてケーブル周囲に捲回されている時、カバー材が縦方向及び横方向の両方向に伸びなければ吸水性樹脂粉末の膨潤能力を阻害することになることから、その伸び易さを示す尺度を、カバー材の長さ方向に対して４５°の角度で採取した試料の５％モジュラス値によって規定した。
【００１８】
４５°の角度の５％モジュラスの上限値を０．２００ｋｇ／５０ｍｍ幅を規定したのは、この値を超えると吸水層の膨潤時低モジュラス布帛が殆ど伸びず、その膨潤能力を著しく阻害するからである。また、その下限は、あまりにも低すぎると、半導電性吸水層への低モジュラス不織布の貼り合わせ時、低モジュラス不織布が伸び過ぎて上手く貼り合わせできないため、５０ｍｍ幅当り０．００１ｋｇ程度までである。
【００１９】
【発明の実施の形態】
以下、本願発明の実施の形態を実施例に基づいて説明する。
【００２０】
図１は、本発明のケーブル用半導電性止水テープの断面構造を示す。ここで、１は半導電性布帛、２は半導電性吸水層、３は半導電性不織布である。
【００２２】
片面膨潤タイプ止水テープは、一面に他面より大きな強度を有する半導電性布帛（以下、高強度布帛と呼ぶ）を、他面に前記のカバー材として作用する半導電性低目付不織布を有している。
【００２４】
片面膨潤タイプ止水テープの場合、半導電性高強度布帛１は、ケーブル用半導電性止水テープにケーブル捲回時やテープ製造時に適切な引張強度を提供する基材よりなり、ポリエステル繊維、ナイロン繊維、アクリル繊維、ポリウレタン繊維、木綿繊維、レーヨン繊維、ポリノジック繊維、ビニロン繊維等の単独又は組み合わせの織物、編物、又は不織布等が使用される。これらの高強度布帛は、止水テープの使用部位に応じて、周知の半導電性ブチルゴム溶剤溶液等の含浸により半導電性にすることができる。
【００２５】
半導電性吸水層２は、外被等が破損してケーブル内に水が浸入した際、水と接触して膨潤し膨潤ゲルを形成して長さ方向や放射状に走水するのを防止するものであり、吸水性樹脂粉末単独、又は吸水性樹脂粉末と合成ゴムや合成樹脂のバインダー、導電剤との組み合わせのいずれも使用できる。
【００２６】
半導電性吸水層２の吸水性樹脂粉末は、水と接触しても溶解せず、自重の１０倍から１０００倍の吸水能力を有する周知の天然変性系及び合成系の代表的にはポリアクリル酸ナトリウム共重合架橋体等のような周知の高吸水性樹脂粉末が使用できる。
【００２７】
図１に３として示す本発明のケーブル用片面膨潤性タイプ止水テープの半導電性低モジュラス不織布は、前記半導電性高強度布帛上に設置した半導電性吸水層の上に設置される。
【００２８】
低モジュラス不織布としては、材質的には綿繊維、ポリウレタン繊維、ポリエステル繊維、ナイロン繊維、アクリル繊維、ポリプロピレン繊維、レーヨン繊維、ポリノジック繊維、ビニロン繊維等の不織布が好適である。とくに、不織布の場合、水流交絡法によって不織ウエッブの繊維を結合したものが好適である。この低モジュラス不織布も予め周知の半導電性ブチルゴム溶剤溶液等に含浸して半導電性にすることができる。
【００２９】
この半導電性低モジュラス不織布は、半導電性高強度布帛の上に、例えば、前記の吸水性樹脂粉末と導電剤を含むバインダーよりなる周知の吸水性樹脂溶剤溶液を塗布し、その上に周知の積層方法により貼り合わせられる。或いは、半導電性高強度布帛の上に吸水性樹脂粉末を均一に撒布し、その上に半導電性低モジュラス不織布を設置し二本のロール間で加圧して積層される。
【００３０】
具体的に、以下の要領で電力ケーブル用半導電性止水テープを以下の要領で製造した。
【００３１】
実施例１（電力ケーブル用半導電性止水テープ）
周知の半導電性ブチルゴム溶剤溶液（固形分：２３％）に溶液６５０重量部にポリアクリル酸ナトリウム系吸水性樹脂粉末（蒸留水吸水倍率：３００ｇ／ｇ、平均粒子径：１００μｍ）４５０重量部を添加し、充分に攪拌して半導電性吸水性樹脂溶剤溶液を得た。
【００３２】
高強度布帛であるポリエステル長繊維不織布（目付６０ｇ／ｍ^２）の片面に周知の半導電性ブチルゴム溶剤溶液を乾燥付着量３０ｇ／ｍ^２で塗布・乾燥した。次いで、その反対面に上記半導電性吸水性樹脂溶剤溶液を塗布し乾燥付着量１８０ｇ／ｍ^２で塗布・乾燥し、直ちに低モジュラス不織布である予め半導電性処理を施した水流交絡法で繊維を接合したセルローズ長繊維不織布（目付：１８ｇ／ｍ^２）を塗布面に載せ、２本ロールで圧着して本発明の電力ケーブル用半導電性止水テープを得た。
【００３３】
参考例（電力ケーブル用絶縁性止水テープ）
高強度布帛であるアクリル樹脂で繊維を結合された乾式法ポリエステル短繊維不織布（目付６０ｇ／ｍ^２）の片面にポリアクリル酸ナトリウム系吸水性樹脂粉末（蒸留水吸水倍率：３００ｇ／ｇ、平均粒子径：１００μｍ）を付着量３５ｇ／ｍ^２で撒布し、直ちに低モジュラス布帛である婦人用ナイロンストッキング用編物（目付：６７ｇ／ｍ^２）を載せ、２本ロールで圧着して電力ケーブル用絶縁性止水テープを得た。
【００３５】
比較例１
実施例１において低モジュラス不織布である水流交絡法で繊維を接合したセルローズ長繊維不織布の代りに、従来技術の低目付不織布カバー材であるスパンボンド法ポリエステル長繊維不織布（目付：１２ｇ／ｍ^２）を使用し、従来技術の電力ケーブル用半導電性止水テープを得た。
【００３６】
比較例２
参考例において低モジュラス布帛である婦人用ナイロンストッキング用編物の代りに、従来技術の低目付不織布カバー材であるアクリル樹脂で繊維を結合した乾式法ポリエステル短繊維不織布（目付：２０ｇ／ｍ^２）を使用し従来技術の電力ケーブル用絶縁性止水テープを得た。
【００３７】
上記実施例と、参考例と比較例について、カバー材の４５°の角度で採取した試料の５％モジュラス値と、吸水高さ、それに耳部固定時吸水高さを調べた。
【００３８】
使用前の低モジュラス布帛を、広幅シートから長さ方向に対して４５°の角度を持たせて幅５０ｍｍ・長さ２５０ｍｍの試験片を採取し、引張試験機を使用して掴み間隔２００ｍｍ、引張速度１００ｍｍ／分で試験片を引張り、５％伸張時の引張強度を求めた結果、何れも、この止水テープのカバー材の５％モジュラス特性は、長さ方向に対して４５°の角度で採取した試料の５０ｍｍ幅当たり、０．０１〜０．０７ｋｇ以下であった。一方、従来技術で使用されている比較例１及び２のカバー材の５％モジュラス特性は、長さ方向に対して４５°の角度で採取した試料の５０ｍｍ幅当たり、０．２５ｋｇ及び０．４０ｋｇであった。
【００３９】
そして、得られた止水テープの吸水高さと、耳部固定時吸水高さを調べた結果、それぞれ１３．５〜１５．５ｍｍと、８．２〜１５．４ｍｍであり、一方、比較例１と比較例２の止水テープの吸水高さと、耳部固定時の吸水高さはそれぞれ１５．５ｍｍ〜１５．０ｍｍと、３．０ｍｍ〜２．８ｍｍであり、本発明の止水テープは重ね合わせて使用されても吸水高さは、著しく高いものであった。尚、ここでいう耳部固定時吸水高さとは、前記の特許第３２１２２５１号に記載されている吸水高さ測定装置において、下型カップの周囲縁に肉厚１０ｍｍのプラスチック円筒状リングを押し付けて止水テープ試験片の円周縁を固定して外径が２０ｍｍ小さい上蓋を載せて測定される吸水高さである。
【００４０】
又、実施例１と比較例１の半導電性止水テープ及び吸水導電処理を施していない銅線織り込みテープを併用して前記特許第３２１２２５１号記載と同様な方法で模擬ケーブルの止水試験を行った結果、実施例１のテープ使用では８０ｃｍで止水していたが、比較例１のテープでは止水試験開始後１０分間で模擬ケーブル端末から漏水した。
【００４１】
【発明の効果】
１．本発明のケーブル用止水テープは、膨潤面に使用する低モジュラス布帛の４５°角度の５％モジュラス値が従来のカバー材に較べて低いので、吸水性樹脂粉末の膨潤能力を向上し、著しくケーブルの止水能力を高める。
【００４２】
２．吸水性樹脂粉末の付着量を低減でき、従来技術品より安価に製造できる。
【００４３】
３．突合せ共巻きは勿論重ね合わせ巻き等のように止水テープが拘束された状態で使用されても吸水高さが従来品に較べて高いので大きな隙間、例えば電力ケーブルの金属コルゲートの大きな谷間も止水できる。その際、未処理の銅線織り込みテープが併用でき、ケーブルのコストダウンと納期短縮に貢献する。
【００４４】
４．電力ケーブルにおいて、本発明のケーブル用半導電性止水テープは、導体抑え巻き、コア上クッション層、金属遮蔽層（銅テープや銅ワイヤー）上下にも適用できる。
【００４６】
５．水と接触してもカバー材表面から膨潤吸水性樹脂粉末が露出しないので、従来（１ｍ）より高い水圧でケーブルの止水試験を行っても膨潤吸水性樹脂粉末が押し流されない。従って、海底ケーブルにも適用できる。
【図面の簡単な説明】
【図１】本発明のケーブル用半導電性止水テープの断面図である。
【符号の説明】
１‥‥半導電性高強度布帛
２‥‥半導電性吸水層
３‥‥半導電性低モジュラス不織布 [0001]
[Industrial application fields]
The present invention relates to a water-stopping tape that is used by being wound in a cable in order to prevent the intrusion and movement of water radially and in the lengthwise direction when a jacket of the power cable is damaged.
[0002]
[Prior art]
The applicant of the present application previously disclosed an ultra-high pressure corrugated metal power cable using two types of water-stopping tape that can more reliably prevent corrugated metal exterior grooves and running water in the gap in Japanese Patent No. 3212251.
[0003]
This waterproof tape is composed of a first tape in which a water absorbent semiconductive rubber composition is impregnated on both sides of a textile base material in which several copper wires are woven in the length direction, and the copper wire is exposed on the surface. A semiconductive rubber composition is applied to one side of a woven fabric base, a water absorbent semiconductive rubber composition is applied to the other side, and a low-weight non-woven fabric cover material is pasted on the coated layer of the water absorbent semiconductive rubber composition. It consists of the combination of the 2nd tape which match | combined, and each tape is used by winding together on the extrusion external semiconductive layer (under metal corrugate) of a metal corrugated armored cable.
[0004]
As a result, both tapes are wound with the water-absorbing surface facing outward between the extruded outer semiconductive layer and the metal corrugated sheath, so that both tapes are damaged when the metal corrugated sheath breaks and water enters the cable. Absorbs water and swells at the same time. And when the moisture permeates from the outside, the low-weight nonwoven fabric cover material of the second tape acts as a swelling dam for storing the swollen gel-like material of the water-absorbing rubber composition, and the water-absorbing rubber It has the function of preventing the swollen gel-like material of the composition from being washed away by water pressure and preventing running water at a short distance.
[0005]
Accordingly, the water-stopping tape disclosed in the above patent exhibits a water-stopping effect that is extremely excellent in the water-stopping ability of the metal corrugated portion having a very large gap space.
[0006]
In addition, the metal corrugated metal cloth corrugated as a single cloth with a small swelling surface of a general cable waterproofing tape comprising a semiconductive or insulating water absorbing layer sandwiched between two semiconductive or insulating cloths. A low-weight nonwoven fabric cover material having a relatively small interfiber gap (gap) used for power cables and the like, and gaps disclosed in JP-A-3-224729 and JP-A-5-92525 Two types of special non-woven cover materials are used.
[0007]
[Problems to be solved by the invention]
Recently, however, metal corrugated power cables have been examined from the cost aspect of this type of waterproof tape, and in particular, several copper wires of the first tape have been woven in the length direction. It has been pointed out as a problem that cost and labor are impeded by the time and effort required for the impregnation treatment of the water-absorbing semiconductive rubber composition on both sides of the textile substrate.
[0008]
Therefore, in order to reduce the cost of the tape itself, the impregnation treatment of the water-absorbing semiconductive rubber composition on both sides of the fabric base material in which several copper wires of the first tape are woven in the length direction is omitted. The method of relying on the waterproof function due to the action as a swelling dam by the tape of No. 2 has been studied, and attempts have been made to reduce the cost by this.
[0009]
However, in order to maintain the water-stopping function as a whole due to a significant decrease in the water-absorbing ability due to the reduction of the water-absorbing semiconductive rubber composition on the first tape, There is a need to greatly increase functionality.
[0010]
Since the second tape uses a cloth having a relatively small gap as a cover material, even if the metal corrugated sheath of the power cable is in contact with water at the time of breakage, the swollen water absorption in the semiconductive water absorption layer The conductive resin powder hardly penetrates the cover material and is exposed on the surface of the cover material, forming a so-called “swelling dam” in which the swollen water-absorbing resin that is not exposed on the surface is accumulated. It has the function to demonstrate.
[0011]
However, the function of the second tape is wound under tension on the extruded semiconductive layer when used with the first tape on the semiconductive layer of the metal corrugated power cable, It was found that the cover material of the second tape was wound in a tensioned state, and as a result, the cover material of the water-stopping tape significantly inhibited the swelling ability of the water-absorbing layer of the water-stopping tape. .
[0012]
That is, when the water absorbent resin powder is attached onto the base fabric, the cover material sandwiches the water absorbent resin powder between the base fabric and the fabric as the cover material to prevent the water absorbent resin powder from falling off. However, in actuality, the waterproof tape for cables is wound around the use site in the cable in a state of being spirally pulled or superposed on the spiral, or folded in the length direction. In general, the entire cover material and ears of the water-stopping tape are in a state of being restrained under tension or by overlapping, and when the cover material comes into contact with water, the swelling of the water-absorbent resin powder is suppressed, and conductivity or insulation is achieved. The water-absorbing capacity of the water-absorbing layer is significantly inhibited. Therefore, in the second tape, it has been found that even if the amount of the superabsorbent resin powder is increased to increase the water absorption capacity, practically it does not contribute to the improvement of the water stoppage capacity after winding the cable. .
[0013]
On the other hand, a special nonwoven fabric cover material with a large gap as at least one piece of fabric is expensive because the manufacturing method is special and complicated, but with respect to the particle size of the water-absorbent resin powder of the water-absorbing layer, a powder with a small particle size is used. In such a case, the water-absorbent resin powder penetrates the gaps and is exposed on the cover material when contacted with water. However, when such a cover material with a large gap is used for the metal corrugated power cable, the water-absorbing resin powder is exposed from the surface of the cover material of the water-stopping tape. There is a defect that it cannot be used in such a large gap space part because it is washed away and cannot exhibit its water stopping ability. In addition, recently, with the expansion of the use of water-carrying prevention type power cables, the water head pressure used for cable water-stop testing has been gradually increased from the conventional 1m height to several tens of meters, and a special nonwoven fabric cover with a large gap. In the case of the material, when the swollen water-absorbing powder is exposed on the surface of the cover material through the cover material when in contact with water, the powder is pushed away more and more due to the water pressure, and the water stopping ability cannot be exhibited. Cannot be used for cables to which is applied.
[0014]
The present invention relates to a waterproofing tape for a cable comprising a semiconductive water-absorbing layer sandwiched between two semiconductive fabrics, and by improving at least one semiconductive cover material fabric, Provided is a cable waterproofing tape having excellent water stopping capability that can be used for a submarine cable to which a high water pressure is applied as well as such a large gap.
[0015]
[Means for Solving the Problems]
The present invention has a limit in the water-stopping ability of the water-stopping tape using such a conventional low-weight non-woven fabric with a relatively small gap or a special non-woven fabric with a large gap as a cover material, and the intrusion due to the breakage of the cable sheath This can be achieved by making the swelled water-absorbing layer formed by gelation of the water-absorbing composition contained in the water-absorbing layer more functioning in the dam action stored in the location of the cover material. It was completed with the knowledge that the water stopping ability of the water stopping tape can be improved.
[0016]
That is, as a characteristic of the cover material cloth according to the present invention, a 5% modulus of a sample collected at an angle of 45 ° with respect to the length direction of the cover material cloth is effective up to 0.200 kg per 50 mm width. The function of the “swelling dam” can be exhibited, and the smaller the modulus value, the better. That is, the water-stopping tape of the present invention exhibits a water-stopping function due to the function of the “swelling dam” of the gelled water-absorbing composition by using a cover material called a low modulus fabric having low modulus characteristics. is there.
[0017]
In general, the 5% modulus value refers to a measure of the ease of extension or flexibility of a material when a low load is applied. In the case of the present invention, when the water-absorbing resin powder swells by contact with water, when the water-stopping tape is pulled and abutted or partially overlapped and wound around the cable, the cover material is in the longitudinal direction. Since the swelling ability of the water-absorbent resin powder is hindered if it does not extend in both the lateral direction and the lateral direction, a scale indicating the ease of the elongation is taken at an angle of 45 ° with respect to the length direction of the cover material. It was defined by the 5% modulus value of the sample.
[0018]
The upper limit value of 5% modulus at an angle of 45 ° is defined as 0.200 kg / 50 mm width because if the value exceeds this value, the low modulus fabric hardly expands when the water absorbing layer swells, and the swelling ability is significantly inhibited. It is. Also, if the lower limit is too low, when the low modulus nonwoven fabric is bonded to the semiconductive water-absorbing layer, the low modulus nonwoven fabric is too stretched and cannot be bonded well, so it is up to about 0.001 kg per 50 mm width. .
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described based on examples.
[0020]
FIG. 1 shows a cross-sectional structure of a semiconductive waterproofing tape for cable according to the present invention. Here, 1 is a semiconductive fabric, 2 is a semiconductive water absorbing layer, and 3 is a semiconductive nonwoven fabric .
[0022]
A single-sided swelling type waterproofing tape has a semiconductive fabric (hereinafter referred to as a high-strength fabric) having greater strength than the other side on one side and a semiconductive low-weight nonwoven fabric that acts as the cover material on the other side. is doing.
[0024]
In the case of a single-side swelling type waterproofing tape, the semiconductive high-strength fabric 1 is made of a base material that provides an appropriate tensile strength to the semiconductive waterproofing tape for cables when the cable is wound or when the tape is manufactured. Nylon fiber, acrylic fiber, polyurethane fiber, cotton fiber, rayon fiber, polynosic fiber, vinylon fiber, or the like alone or in combination is used. These high-strength fabrics can be made semiconductive by impregnation with a well-known semiconductive butyl rubber solvent solution or the like depending on the use site of the water blocking tape.
[0025]
The semiconductive water-absorbing layer 2 prevents the water from running in the length direction or radially by forming a swollen gel by contacting and swelling with water when the outer sheath or the like is damaged and water enters the cable. Any of the water-absorbent resin powders alone or a combination of the water-absorbent resin powders with a synthetic rubber or synthetic resin binder or conductive agent can be used.
[0026]
The water-absorbent resin powder of the semiconductive water-absorbing layer 2 does not dissolve even when it comes into contact with water, and is typically a well-known natural modified and synthetic system having a water absorption capacity of 10 to 1000 times its own weight. A well-known superabsorbent resin powder such as sodium acid copolymer crosslinked product can be used.
[0027]
The semiconductive low modulus nonwoven fabric of the single-side swellable waterproofing tape for cable of the present invention shown as 3 in FIG. 1 is installed on a semiconductive water-absorbing layer installed on the semiconductive high-strength fabric.
[0028]
As the low modulus nonwoven fabric , non-woven fabrics such as cotton fiber, polyurethane fiber, polyester fiber, nylon fiber, acrylic fiber, polypropylene fiber, rayon fiber, polynosic fiber, and vinylon fiber are suitable. In particular, in the case of non-woven fabrics, those obtained by binding non-woven web fibers by the hydroentanglement method are suitable. This low modulus nonwoven fabric can also be made semiconductive by impregnating it in advance with a known semiconductive butyl rubber solvent solution or the like.
[0029]
This semiconductive low modulus nonwoven fabric is obtained by, for example, applying a well-known water-absorbing resin solvent solution composed of a binder containing the above water-absorbing resin powder and a conductive agent on a semi-conductive high-strength fabric, and then well-known thereon. The lamination method is used. Alternatively, the water-absorbent resin powder is uniformly spread on a semiconductive high-strength fabric, and a semiconductive low modulus nonwoven fabric is placed thereon and pressed between two rolls to be laminated.
[0030]
Specifically, a semiconductive waterproofing tape for electric power cables was produced in the following manner.
[0031]
Example 1 (Semiconductive waterproofing tape for power cable)
450 parts by weight of a sodium polyacrylate-based water absorbent resin powder (distilled water absorption ratio: 300 g / g, average particle size: 100 μm) is added to 650 parts by weight of a known semiconductive butyl rubber solvent solution (solid content: 23%). The mixture was added and sufficiently stirred to obtain a semiconductive water-absorbent resin solvent solution.
[0032]
A well-known semiconductive butyl rubber solvent solution was applied and dried at a dry adhesion amount of 30 g / m ² on one side of a high-strength polyester non-woven fabric (weight per unit: 60 g / m ² ). Next, the semiconductive water-absorbing resin solvent solution is applied to the opposite surface, applied and dried at a dry adhesion amount of 180 g / m ² , and immediately followed by a hydroentanglement method in which a semi-conductive treatment that is a low modulus nonwoven fabric is applied in advance. Cellulose long fiber nonwoven fabric (weight per unit: 18 g / m ² ) bonded to was applied on the coated surface and pressure-bonded with two rolls to obtain a semiconductive waterproofing tape for power cables of the present invention.
[0033]
Reference example (insulating waterproof tape for power cables)
Polyacrylate sodium water-absorbent resin powder (distilled water absorption ratio: 300 g / g, average particle) on one side of a dry-type polyester short fiber nonwoven fabric (weight per unit: 60 g / m ² ) in which fibers are bonded with an acrylic resin which is a high-strength fabric (Diameter: 100 μm) with an adhesion amount of 35 g / m ² , and immediately put a knitted fabric for women's nylon stockings (weight per unit: 67 g / m ² ), which is a low modulus fabric , and crimp with two rolls to insulate the power cable A waterstop tape was obtained.
[0035]
Comparative Example 1
In place of the cellulose long fiber nonwoven fabric in which fibers are joined by the hydroentanglement method which is a low modulus nonwoven fabric in Example 1, a spunbond polyester long fiber nonwoven fabric (weight per unit: 12 g / m ² ) which is a low-weight nonwoven fabric cover material of the prior art Was used to obtain a semiconductive waterproofing tape for a power cable of the prior art.
[0036]
Comparative Example 2
In the reference example , instead of the knitted fabric for women's nylon stockings which is a low modulus fabric, a dry method polyester short fiber nonwoven fabric (weight per unit: 20 g / m ² ) in which fibers are bonded with an acrylic resin which is a conventional low-weight nonwoven fabric cover material. Insulating waterproof tape for power cables of the prior art was obtained.
[0037]
With respect to the above examples, the reference example and the comparative example, the 5% modulus value, the water absorption height, and the water absorption height at the time of fixing the ear portion of the sample collected at an angle of 45 ° of the cover material were examined.
[0038]
A low-modulus fabric before use is taken from a wide sheet at a 45 ° angle with respect to the length direction, and a specimen having a width of 50 mm and a length of 250 mm is collected, and a tensile tester is used to hold a grip interval of 200 mm. The test piece was pulled at a speed of 100 mm / min, and the tensile strength at 5% elongation was obtained. As a result, the 5% modulus characteristic of the cover material of this waterproofing tape was 45 ° with respect to the length direction. It was 0.01 to 0.07 kg or less per 50 mm width of the collected sample. On the other hand, the 5% modulus characteristics of the cover materials of Comparative Examples 1 and 2 used in the prior art are 0.25 kg and 0.40 kg per 50 mm width of a sample collected at an angle of 45 ° with respect to the length direction. Met.
[0039]
And as a result of investigating the water absorption height of the obtained water-stopping tape and the water absorption height at the time of fixing the ear portion, they were 13.5 to 15.5 mm and 8.2 to 15.4 mm, respectively. The water-absorbing height of the water-stopping tape of Comparative Example 2 and the water-absorbing height when the ears are fixed are 15.5 mm to 15.0 mm and 3.0 mm to 2.8 mm, respectively. Even when used together, the water absorption height was remarkably high. The water absorption height at the time of fixing the ear part here refers to a water absorption height measuring device described in the above-mentioned Japanese Patent No. 3212251 by pressing a plastic cylindrical ring having a wall thickness of 10 mm against the peripheral edge of the lower mold cup. This is the water absorption height measured by fixing the circular peripheral edge of the water-stopping tape test piece and placing an upper lid with an outer diameter of 20 mm.
[0040]
Moreover, the water stop test of the simulated cable was conducted in the same manner as described in the above-mentioned Japanese Patent No. 3212251 by using the semiconductive water stop tape of Example 1 and Comparative Example 1 and the copper wire woven tape not subjected to water absorption conductive treatment in combination. As a result, water was stopped at 80 cm when the tape of Example 1 was used, but the tape of Comparative Example 1 leaked from the simulated cable terminal 10 minutes after the start of the water stop test.
[0041]
【The invention's effect】
1. The waterproof tape for cable according to the present invention has a low 5% modulus value of 45 ° angle of the low modulus fabric used for the swelling surface, which is lower than that of the conventional cover material. Increase the water stopping ability of the cable.
[0042]
2. The adhesion amount of the water-absorbent resin powder can be reduced, and it can be manufactured at a lower cost than the prior art products.
[0043]
3. Of course, even when used in a state where the waterproofing tape is constrained, such as lap winding, the water absorption height is higher than that of the conventional product, so a large gap, for example, a large valley in the metal corrugation of the power cable is also stopped. I can water. At that time, untreated copper wire woven tape can be used together, which contributes to cable cost reduction and delivery time reduction.
[0044]
4). In a power cable, the semiconductive waterproofing tape for cable of the present invention can be applied to a conductor holding winding, a cushion layer on the core, and a metal shielding layer (copper tape or copper wire).
[0046]
5 . Since the swollen water-absorbent resin powder is not exposed from the surface of the cover material even when it comes into contact with water, the swollen water-absorbent resin powder will not be washed away even if a waterproof test of the cable is performed at a higher water pressure than the conventional (1 m). Therefore, it can also be applied to submarine cables.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a semiconductive waterproofing tape for cable according to the present invention.
[Explanation of symbols]
1 Semiconductive high strength fabric 2 Semiconductive water absorption layer 3 Semiconductive low modulus nonwoven fabric

Claims

Intrusion of water in the radial and length directions due to the water-stopping action of the swollen dam of the gelled water-absorbent composition when the jacket of the power cable is damaged and wound under the metal corrugated power cable In order to prevent such movement, a low-modulus material in which a semiconductive fabric having strength greater than that of the other surface installed on one surface and a web fiber by a hydroentanglement method acting as a cover material installed on the other surface is combined. In the waterproof tape for single-sided swelling type cable in which a semiconductive water-absorbing layer is inserted in a sandwich between the semiconductive nonwoven fabric,
The low modulus semi-conductive nonwoven fabric acting as the cover material has a stretchability when applied with a low load per 50 mm width in a 5% modulus characteristic of a sample taken at an angle of 45 ° with respect to the length direction of the nonwoven fabric. A waterproofing tape for cables of 0.200 kg or less and 0.001 kg or more.