JPH0570959B2 - - Google Patents
Info
- Publication number
- JPH0570959B2 JPH0570959B2 JP59004521A JP452184A JPH0570959B2 JP H0570959 B2 JPH0570959 B2 JP H0570959B2 JP 59004521 A JP59004521 A JP 59004521A JP 452184 A JP452184 A JP 452184A JP H0570959 B2 JPH0570959 B2 JP H0570959B2
- Authority
- JP
- Japan
- Prior art keywords
- thermoplastic resin
- layer
- conductive
- filler
- sheet
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 239000010410 layer Substances 0.000 claims description 63
- 229920005992 thermoplastic resin Polymers 0.000 claims description 60
- 239000000945 filler Substances 0.000 claims description 28
- 239000012792 core layer Substances 0.000 claims description 20
- 239000011231 conductive filler Substances 0.000 claims description 15
- 239000002131 composite material Substances 0.000 claims description 11
- 230000035699 permeability Effects 0.000 claims description 10
- 239000002985 plastic film Substances 0.000 claims description 9
- 229920005989 resin Polymers 0.000 description 27
- 239000011347 resin Substances 0.000 description 27
- 230000000694 effects Effects 0.000 description 24
- PPBRXRYQALVLMV-UHFFFAOYSA-N Styrene Chemical compound C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 description 18
- 229920003023 plastic Polymers 0.000 description 12
- 239000004033 plastic Substances 0.000 description 12
- 230000000704 physical effect Effects 0.000 description 11
- 238000001125 extrusion Methods 0.000 description 10
- 238000010030 laminating Methods 0.000 description 8
- 238000000034 method Methods 0.000 description 8
- 239000000203 mixture Substances 0.000 description 8
- 229910052751 metal Inorganic materials 0.000 description 7
- 239000002184 metal Substances 0.000 description 7
- 239000012790 adhesive layer Substances 0.000 description 6
- 239000000835 fiber Substances 0.000 description 6
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 5
- 229910052782 aluminium Inorganic materials 0.000 description 5
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 5
- VXNZUUAINFGPBY-UHFFFAOYSA-N 1-Butene Chemical compound CCC=C VXNZUUAINFGPBY-UHFFFAOYSA-N 0.000 description 4
- 229910001369 Brass Inorganic materials 0.000 description 4
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- 239000010951 brass Substances 0.000 description 4
- 239000006229 carbon black Substances 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 229910000889 permalloy Inorganic materials 0.000 description 4
- 229920005604 random copolymer Polymers 0.000 description 4
- 238000007666 vacuum forming Methods 0.000 description 4
- 229910000859 α-Fe Inorganic materials 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- 229920000049 Carbon (fiber) Polymers 0.000 description 3
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 3
- 239000005977 Ethylene Substances 0.000 description 3
- 229920000122 acrylonitrile butadiene styrene Polymers 0.000 description 3
- 239000000654 additive Substances 0.000 description 3
- 238000005452 bending Methods 0.000 description 3
- 239000004917 carbon fiber Substances 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 239000011888 foil Substances 0.000 description 3
- 238000004898 kneading Methods 0.000 description 3
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- -1 vinyl aromatic compound Chemical class 0.000 description 3
- 229910000640 Fe alloy Inorganic materials 0.000 description 2
- RRHGJUQNOFWUDK-UHFFFAOYSA-N Isoprene Chemical compound CC(=C)C=C RRHGJUQNOFWUDK-UHFFFAOYSA-N 0.000 description 2
- BZHJMEDXRYGGRV-UHFFFAOYSA-N Vinyl chloride Chemical compound ClC=C BZHJMEDXRYGGRV-UHFFFAOYSA-N 0.000 description 2
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 2
- 239000000853 adhesive Substances 0.000 description 2
- 230000001070 adhesive effect Effects 0.000 description 2
- KAKZBPTYRLMSJV-UHFFFAOYSA-N butadiene group Chemical group C=CC=C KAKZBPTYRLMSJV-UHFFFAOYSA-N 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 229920001577 copolymer Polymers 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000007733 ion plating Methods 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- XWHPIFXRKKHEKR-UHFFFAOYSA-N iron silicon Chemical compound [Si].[Fe] XWHPIFXRKKHEKR-UHFFFAOYSA-N 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 239000003973 paint Substances 0.000 description 2
- 238000007747 plating Methods 0.000 description 2
- 239000011802 pulverized particle Substances 0.000 description 2
- 239000002356 single layer Substances 0.000 description 2
- 238000005507 spraying Methods 0.000 description 2
- 238000004544 sputter deposition Methods 0.000 description 2
- 229910000815 supermalloy Inorganic materials 0.000 description 2
- 229920001169 thermoplastic Polymers 0.000 description 2
- 239000004416 thermosoftening plastic Substances 0.000 description 2
- 238000011282 treatment Methods 0.000 description 2
- 238000001771 vacuum deposition Methods 0.000 description 2
- 229910052725 zinc Inorganic materials 0.000 description 2
- 239000011701 zinc Substances 0.000 description 2
- PMJHHCWVYXUKFD-SNAWJCMRSA-N (E)-1,3-pentadiene Chemical group C\C=C\C=C PMJHHCWVYXUKFD-SNAWJCMRSA-N 0.000 description 1
- JLBJTVDPSNHSKJ-UHFFFAOYSA-N 4-Methylstyrene Chemical compound CC1=CC=C(C=C)C=C1 JLBJTVDPSNHSKJ-UHFFFAOYSA-N 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- 229910001030 Iron–nickel alloy Inorganic materials 0.000 description 1
- 241000209490 Nymphaea Species 0.000 description 1
- 235000016791 Nymphaea odorata subsp odorata Nutrition 0.000 description 1
- NIXOWILDQLNWCW-UHFFFAOYSA-N acrylic acid group Chemical group C(C=C)(=O)O NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 1
- 229920001400 block copolymer Polymers 0.000 description 1
- WYDVQMAEAOAAAJ-UHFFFAOYSA-N chromium copper iron nickel Chemical compound [Fe][Cr][Cu][Ni] WYDVQMAEAOAAAJ-UHFFFAOYSA-N 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- DIOQZVSQGTUSAI-UHFFFAOYSA-N decane Chemical compound CCCCCCCCCC DIOQZVSQGTUSAI-UHFFFAOYSA-N 0.000 description 1
- 150000001993 dienes Chemical class 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000010292 electrical insulation Methods 0.000 description 1
- 229920006226 ethylene-acrylic acid Polymers 0.000 description 1
- 239000003365 glass fiber Substances 0.000 description 1
- 230000007257 malfunction Effects 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 239000010445 mica Substances 0.000 description 1
- 229910052618 mica group Inorganic materials 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 239000008188 pellet Substances 0.000 description 1
- PMJHHCWVYXUKFD-UHFFFAOYSA-N piperylene Natural products CC=CC=C PMJHHCWVYXUKFD-UHFFFAOYSA-N 0.000 description 1
- 229920002863 poly(1,4-phenylene oxide) polymer Polymers 0.000 description 1
- QQONPFPTGQHPMA-UHFFFAOYSA-N propylene Natural products CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 description 1
- 125000004805 propylene group Chemical group [H]C([H])([H])C([H])([*:1])C([H])([H])[*:2] 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 238000007740 vapor deposition Methods 0.000 description 1
- 229920002554 vinyl polymer Polymers 0.000 description 1
Description
本発明は、高度な電磁波遮蔽性を有する複合プ
ラスチツクシートに関するものであり、更に詳し
くは、熱可塑性樹脂に対して、粉末状及び／又は
繊維状の、高透磁性フイラーを含有させた層を中
芯層とし、その両面に導電性熱可塑性樹脂を積層
し、更にその両面又は片面に熱可塑性樹脂を積層
してなる高度な電磁波遮蔽性を有し、成形加工性
及び物性に優れた複合プラスチツクシートに関す
るものである。
従来、事務機器、電子計算機、TVレシーバー
などの電子機器は、それ自体が電磁波の発生源と
なり得るものであり、また、周囲の電気機器によ
つても影響を受け、誤動作やノイズの原因となつ
ている。
さらに、電子機器の筐体には、板金やアルミダ
イキヤストなどが使用されていたが、この場合は
電磁波による障害はある程度防止できた。
しかしながら近年、成形の容易さ、自由なデザ
イン、軽さ、などのメリツトより、プラスチツク
材料が電子機器の筐体に使用される例が増加して
いる。
プラスチツク材料は、一般に電気絶縁性が高
く、電磁波に対しては透明である為に、そのまま
では遮蔽効果が期待できないので、電子機器の筐
体にプラスチツク材料を用いる場合は、遮蔽処理
が必要となる。
特に最近では、電子機器からの電磁波の放射に
対して、厳しく制限が加えられて居り、遮蔽処理
に対する要求が高まつている。
プラスチツクに遮蔽効果を付与する方法とし
て、従来よりアルミ箔や導電テープの貼り合
せ、亜鉛熔射、導電性塗料、プラスチツク
メツキ、真空蒸着、スパツタリング、イオ
ンプレーテイング、導電性フイラー混入プラス
チツクコンパウンドなど数多くの方法が検討され
ている。
まず、
(1) アルミ箔や導電テープの貼り合せによる遮蔽
効果の付与は、作業に熟練を要する上に複雑な
形状に適さないなどの欠点を有する。
(2) 亜鉛熔射や導電性塗料の塗工は、現在最も一
般的に用いられる方法であるが、複雑な形状で
は膜厚が不均一になる上に、密着性が不充分
で、導電層の剥落により火災の危険があるとさ
れる。
(3) プラスチツクメツキは、耐久性、密着性が良
好であるが、ベースとなるプラスチツクに制限
がある。さらに、大型品に不向きなどの欠点を
有する。
(4) 真空蒸着、スパツタリング、イオンプレーテ
イングなどは蒸着技術の応用で、良好な遮蔽効
果が得られるが、装置が高価である上に、高度
な技術が必要であるので、コマーシヤルベース
では殆んど行なわれていない。
このように(1)〜(4)に述べてきた様な、プラスチ
ツク成形体の表面に導電層を形成する手法は種々
あるが、導電性フイラーをプラスチツク中に分散
し複合材としたものは、導電層の剥落、クラツ
ク、腐食などの心配がない。
しかしながら、この複合材は、導電性フイラー
を多量に加えないと、電磁波遮蔽効果が上がらな
いので、ベースとなるプラスチツクの基本物性を
損なつたり、また押出時の流動特性を損なう為、
成形が困難になる欠点があつた。
更に、たとえ導電性フイラーを多量に加えて
も、低インピーダンス電磁波に対する充分な遮蔽
効果は得ることが出来ず、低インピーダンス電磁
波に対する遮蔽材としての要求に応える事は出来
なかつた。
本発明は、導電性フイラーをプラスチツク中に
分散する遮蔽効果付与法のかかる欠点を解決した
ものであり、熱可塑性樹脂に対して高透磁性フイ
ラーを含有させた層を中芯層とし、その両面に導
電性熱可塑性樹脂を一体に積層し、更にその両面
又は片面に熱可塑性樹脂を積層することにより、
高透磁性フイラー含有熱可塑性樹脂層と導電性熱
可塑性樹脂層との間の、極めて大きなインピーダ
ンス不整合効果により、高透磁性フイラーや導電
性フイラーを少量添加することで、良好な電磁波
遮蔽効果及び低インピーダンス電磁波に対する充
分な遮蔽効果を有し、高透磁性フイラーや導電性
フイラー分散層を押出も安定化し、かつ２次加工
適性にも優れ、更に、複合シートの機械的強度、
耐折性及び耐衝撃性にも優れた、複合プラスチツ
クシートを提供しようとするものである。
すなわち本発明は、10キロヘルツにおける比透
磁率100以上の粉末状及び／又は繊維状高透磁性
フイラーを６〜40容量％含有する熱可塑性樹脂フ
イルム又はシートの中芯層の両面に導電性フイラ
ーを６〜40容量％含有する熱可塑性樹脂フイルム
又はシートの中間層を積層し、更に該中間層の片
面又は両面に熱可塑性樹脂フイルム又はシート表
皮層を積層してなることを特徴とする。
以下本発明を更に詳細に説明する。
本発明に用いる表皮層の熱可塑性樹脂として
は、硬質塩化ビニル樹脂、アクリル変性硬質塩化
ビニル樹脂、一般用のスチレン樹脂、耐衝撃スチ
レン樹脂、ビニル芳香族化合物が、スチレン、α
−メチルスチレン等であり、共役ジエンがブタジ
エン、イソプレン、ピペリレン等であり、その割
合が75〜95：35：５である熱可塑性ブロツク共重
合樹脂、さらにABS樹脂、エチレン樹脂、エチ
レン−１−ブテンランダム共重合体、エチレン−
酢酸ビニル共重合体及びエチレン−アクリル酸エ
ステル共重合体等の変性エチレン樹脂、プロピレ
ン樹脂、カーボネート樹脂、ポリ（２，６ジメチ
ルフエニレンオキシド）及びその誘導体である変
性P.P.O樹脂等を用いることができる。
表皮層として用いる熱可塑性樹脂は単味でも良
く、更に導電性熱可塑性樹脂中間層及び高透磁性
フイラー含有熱可塑性樹脂中芯層との押出流動特
性を合わせる為に、また複合プラスチツクシート
の性能を改良する為に、２種以上の樹脂の混合物
とする事や、添加剤を適量添加する事も出来る。
また、本発明の導電性熱可塑性樹脂からなる中
間層は、機械的強度、剛性、耐衝撃性、及び耐折
強さの様な物性を、表皮層の熱可塑性樹脂層によ
つてもたせる事が出来るので、導電性熱可塑性樹
脂中間層は、上記の様な物性はそれ程強く要求さ
れるものではなく、押出加工時の流動性を表皮層
の熱可塑性樹脂及び高透磁性フイラー含有熱可塑
性樹脂に合せる事や、熱可塑性樹脂表皮層及び高
透磁性フイラー含有熱可塑性樹脂中芯層との密着
性又は接着剤を介する場合にあつては、接着層と
の密着性を高める事が重要となる。
この目的から、導電性熱可塑性樹脂中間層は、
表皮層と同様な各種の熱可塑性樹脂が、単味もし
くは２種以上の混合物として用いられ、性能に応
じて添加剤を適量用いる事も出来る。
次に、本発明の高透磁性フイラー含有熱可塑性
樹脂からなる中芯層は、機械的強度、剛性、耐衝
撃性、及び耐折強さの様な物性を、表皮層の熱可
塑性樹脂層によつてもたせる事が出来るので、高
透磁性フイラー含有熱可塑性樹脂中芯層は、上記
の様な物性はそれ程強く要求されるものではな
く、押出加工時の流動性を、導電性熱可塑性樹脂
中間層に合せる事や、導電性熱可塑性樹脂中間層
との密着性又は接着剤を介する場合にあつては、
接着層との密着性を高める事が重要となる。
この目的から、高透磁性フイラー含有熱可塑性
樹脂中芯層は、熱可塑性樹脂表皮層及び導電性熱
可塑性樹脂中間層と同様な各種の熱可塑性樹脂が
単味もしくは２種以上の混合物として用いられ、
性能に応じて添加剤を適量用いる事も出来る。
本発明に用いる導電性フイラーとしては、
(i) 粒子状のカーボンブラツク、金属粉、黒鉛粉
及びニツケルコート黒鉛粉
(ii) 薄片状のアルミフレークや金属メツキマイカ
(iii) 繊維状のカーボン繊維、金属繊維、及び表面
にアルミニウムをコーテイングした金属化ガラ
ス繊維
であり、単一で用いても、２種以上の併用で用い
ても何ら構わないが、カーボンブラツクとカーボ
ン繊維を併用することで最も良好な結果を得るこ
とができる。
導電性フイラーの添加量は、６〜40容量％、好
ましくは10〜30容量％であり、６容量％未満では
電磁波遮蔽効果が殆んど得られず、40容量％を超
えると、押出加工が困難となり、機械的強度等の
特性値が大きく低下し、２次加工適性も不充分な
ものとなる。
本発明に用いる高透磁性フイラーとしては、10
キロヘルツにおける比透磁率が100以上の粉末状
及び／又は繊維状の金属及び／又は金属酸化物で
あり、具体的には粉末状及び／又は繊維状のスー
パーマロイ、超パーマロイ、パーマロイ、フエラ
イト、純鉄、ケイ素−鉄合金、銅−クロム−ニツ
ケル−鉄合金及びニツケル等が用いられるが、な
かでもスーパーマロイ、超パーマロイ、パーマロ
イ、フエライト、純鉄、ケイ素−鉄合金は良好な
効果を与える。比透磁率が100未満では、電磁波
遮蔽効果が低下し、フイラー量を増大させないと
遮蔽効果が得られない。
高透磁性フイラーの添加量は６〜40容量％、好
ましくは10〜30容量％であり、６容量％未満では
電磁波遮蔽効果が殆んど得られず、40容量％を超
えると、押出加工が困難となり、機械的強度等の
特性値が大きく低下し、２次加工適性も不充分な
ものとなる。
次に、本発明品を製造するには、例えば高透磁
性フイラー含有熱可塑性樹脂中芯層に用いる熱可
塑性樹脂と高透磁性フイラー、及び導電性熱可塑
性樹脂中間層に用いる熱可塑性樹脂と導電性フイ
ラーとを夫々バンバリーミキサー、コニーダー、
押出機等の混練機で混練してペレツトとし、次に
３台の押出機により、熱可塑性樹脂表皮層、導電
性熱可塑性樹脂中間層及び高透磁性フイラー含有
熱可塑性樹脂中芯層の樹脂を夫々供給し、５層ダ
イにより熱可塑性樹脂表皮層、導電性熱可塑性樹
脂中間層及び高透磁性フイラー含有熱可塑性樹脂
中芯層を押出し積層一体化するか、４台の押出機
により、熱可塑性樹脂表皮層、導電性熱可塑性樹
脂中間層、高透磁性フイラー含有熱可塑性樹脂中
芯層及び接着剤層の樹脂を夫々供給し、７層ダイ
より熱可塑性樹脂表皮層、導電性熱可塑性樹脂中
間層、高透磁性フイラー含有熱可塑性樹脂中芯層
及び接着層を積層一体化する。
更に、上記の複合プラスチツクシートを製造す
るにあたつて、熱可塑性樹脂表皮層は導電性熱可
塑性樹脂中間層の片面のみに積層しても良く、こ
の場合接着剤層を介さぬ時には４層ダイを、接着
剤層を介する時には６層ダイを用いる。
更に夫々の樹脂を押出機シリンダー部と、単層
ダイの間に付設した環状流路に供給し、環状流路
内で積層後単層ダイより押出一体化する方法もと
る事が可能である。
この様な共押出方法で得られた、本発明の電磁
波遮蔽性複合プラスチツクシートの全体の肉厚
は、0.2〜10.0mm、好ましくは0.5〜6.0mm程度であ
り、肉厚が0.2mm未満では、圧空又は真空成形で
電子機器の筐体等の成形品とした場合に、機械的
強度、剛性、耐衝撃性、耐折強さなどの物性が低
下する。
一方、肉厚が10.0ｍ／ｍを超えると圧空又は真
空成形が困難となる。また高透磁性フイラー含有
熱可塑性樹脂中芯層の肉厚は、全体の肉厚の2.5
〜35％、好ましくは５〜25％であり、肉厚が2.5
％未満では、押出成形時の製膜が困難になり、更
に充分な電磁波遮蔽効果が得られない。
一方、肉厚が35％を越えると、圧空又は真空成
形が困難となる上に、成形品の、機械的強度等の
物性が不充分なものとなる。
また導電性熱可塑性樹脂中間層の肉厚は、全体
の肉厚の５〜70％、好ましくは10〜50％であり、
肉厚が５％未満では、押出時の製膜が困難にな
り、更に電磁波遮蔽効果が殆んど得られなくな
る。
一方肉厚が70％を超えると、圧空又は真空成形
が困難となる上に、成形品の、機械的強度等の物
性が不充分なものとなる。
以上説明した通り、本発明は高透磁性フイラー
を混入した、高透磁性フイラー含有熱可塑性樹脂
中芯層の両面に導電性フイラーを混入した導電性
熱可塑性樹脂中間層とし、更にその片面又は両面
を熱可塑性樹脂表皮層とした積層シートを作成す
ることにより、各積層樹脂間の押出特性が改善さ
れかつ密着性も良好である。さらに２次加工性に
もすぐれ、シートの機械的強度、耐折性及び耐衝
撃性もすぐれ、また、電気絶縁層が存在するの
で、感電事故を防止できる等の効果がある。
以上本発明を実施例により、更に詳細に説明す
る。
実施例 １〜４
耐衝撃スチレン樹脂は「デンカスチロールHI
−Ｓ−３：電気化学工業(株)商品名」、エチレン−
１−ブテンランダム共重合体樹脂は「タフマーＡ
−4085：三井石油化学(株)商品名」、粉末状フエラ
イトは「BSF−547：戸田工業(株)商品名」を用
い、表に示す様な組成で配合し、その配合物を
2.5バンバリーミキサーで混練した後、粉砕機
で粉砕粒とした。
更に耐衝撃スチレン樹脂は「デンカスチロール
HI−Ｓ−３：電気化学工業(株)商品名」、エチレン
−１−ブテンランダム共重合体樹脂は「タフマー
Ａ−4085：三井石油化学(株)商品名」、カーボンブ
ラツクは「バルカンXC−72：キヤボツト社 商
品名」、黄銅繊維は「アイシン メタルフアイバ
ー：アイシン精密(株)商品名」を用い、表に示す様
な組成で配合し、その配合物を、2.5バンバリ
ーミキサーで混練した後、粉砕機で粉砕粒とし
た。
上記の粉砕粒のうち、フエライト粉を混練した
ものは、40ｍ／ｍ押出機（Ｌ／Ｄ＝24）の供給口
より押出機内に供給し、溶融して５層シートダイ
の中芯層に供給し、カーボンブラツク及び黄銅繊
維を混練したものは、50ｍ／ｍ押出機（Ｌ／Ｄ＝
27）の供給口より押出機内に供給し、溶融して５
層シートダイの中間層２層に供給した。
一方耐衝撃スチレン樹脂を65mmφの押出機
（Ｌ／Ｄ＝25）の供給口より押出機に供給し、溶
融して前記５層シートの表皮層２層に供給した。
ダイは、マニホールドを複数個有し、マニホー
ルドを出た後リツプの手前で樹脂同志が打合う様
になつている。
ダイの巾は600ｍ／ｍ、リツプは6.0ｍ／ｍに調
整され、この結果、中芯層の高透磁性フイラー含
有熱可塑性樹脂層1.0ｍ／ｍ、中間層の導電性熱
可塑性樹脂層各1.0ｍ／ｍ、表面層の耐衝撃性ス
チレン樹脂層各1.0ｍ／ｍシート全体としての厚
さ5.0ｍ／ｍの５層シートを得た。
得られた５層シートは、各層間の密着力が充分
であり、剥離することは不可能であつた。
このシートは表で示す通り、電磁波遮蔽効果、
及び機械的強度等の性能において、いずれもすぐ
れたものであつた。
また、このシートを圧空成形にて、筐体形状と
したところ、電磁波遮蔽効果を充分に保持したま
ま、剛性、耐衝撃性にすぐれた成形品が得られ
た。
実施例 ５
実施例１の、耐衝撃スイレン樹脂とエチレン−
１−ブテンランダム共重合体樹脂のかわりに、
ABS樹脂「デカンABS GR−2000：電気化学工
業(株)商品名」を用いた以外は、実施例１と同様な
操作を行なつた。
物性測定結果は表に示す通り、電磁波遮蔽効果
及び機械的強度等の性能において、すぐれたもの
であつた。
実施例 ６
実施例１の黄銅繊維のかわりに、炭素繊維「ベ
スフアイトHTA−C6S：東邦レーヨン(株)商品名」
を用いた以外は実施例１と同様な操作を行なつ
た。
物性測定結果は表に示す通り、電磁波遮蔽効
果、及び機械的強度等の性能において、すぐれた
ものであつた。
比較例 １〜４
高透磁性フイラー又は導電性フイラーを、特許
請求範囲上限値を超える量、及び下限値に達しな
い量、添加した以外は実施例１と同様な条件で、
肉厚5.0mmのシートを得た。
高透磁性フイラー又は導電性フイラーの添加が
過剰であると、プラスチツクシートの機械的強度
等が失なわれ、不足であると電磁波遮蔽効果が得
られない。
比較例 ５〜６
中芯層に用いるフイラーを黄銅繊維「アイシン
メタルフアイバー：アイシン精機(株)商品名」とニ
ツケルパウダー「福田金属箔粉工業(株)」とを用い
た以外は、実施例１と同様の配合であつた。結果
を表に示す。実施例１に比較して電磁波遮蔽効果
が低下している。
The present invention relates to a composite plastic sheet having high electromagnetic wave shielding properties, and more specifically, the present invention relates to a composite plastic sheet having a high electromagnetic wave shielding property. A composite plastic sheet with advanced electromagnetic shielding properties, excellent moldability and physical properties, made by laminating conductive thermoplastic resin on both sides of the core layer and laminating thermoplastic resin on both or one side of the core layer. It is related to. Conventionally, electronic devices such as office equipment, computers, and TV receivers can themselves be sources of electromagnetic waves, and are also affected by surrounding electrical devices, causing malfunctions and noise. ing. Furthermore, the housings of electronic devices used to be made of sheet metal or die-cast aluminum, which could prevent electromagnetic interference to some extent. However, in recent years, plastic materials have been increasingly used for the housings of electronic devices due to their advantages such as ease of molding, flexible design, and light weight. Plastic materials generally have high electrical insulation properties and are transparent to electromagnetic waves, so they cannot be expected to have a shielding effect as they are, so if plastic materials are used for the housing of electronic devices, shielding treatment is required. . Particularly recently, strict restrictions have been placed on the radiation of electromagnetic waves from electronic devices, and there has been an increasing demand for shielding treatments. Conventionally, there are many methods for imparting a shielding effect to plastics, such as laminating aluminum foil or conductive tape, zinc spraying, conductive paint, plastic plating, vacuum deposition, sputtering, ion plating, and plastic compounds mixed with conductive fillers. Methods are being considered. First, (1) Providing a shielding effect by laminating aluminum foil or conductive tape has drawbacks such as requiring skill and being unsuitable for complex shapes. (2) Zinc spraying and coating with conductive paint are currently the most commonly used methods, but when the shape is complex, the film thickness becomes uneven, the adhesion is insufficient, and the conductive layer There is a risk of fire due to flaking. (3) Plastic plating has good durability and adhesion, but there are limitations to the base plastic. Furthermore, it has drawbacks such as being unsuitable for large items. (4) Vacuum deposition, sputtering, ion plating, etc. are applications of vapor deposition technology that can provide good shielding effects, but they are rarely used on a commercial basis because the equipment is expensive and advanced technology is required. It is not done often. As described above in (1) to (4), there are various methods for forming a conductive layer on the surface of a plastic molded object, but the method that forms a composite material by dispersing conductive filler in plastic is There is no need to worry about peeling off, cracking, or corrosion of the conductive layer. However, the electromagnetic wave shielding effect of this composite material cannot be improved unless a large amount of conductive filler is added, which impairs the basic physical properties of the base plastic, and also impairs the flow characteristics during extrusion.
The drawback was that it was difficult to mold. Furthermore, even if a large amount of conductive filler is added, a sufficient shielding effect against low impedance electromagnetic waves cannot be obtained, and the demand for a shielding material against low impedance electromagnetic waves cannot be met. The present invention solves the drawbacks of the method of imparting a shielding effect by dispersing a conductive filler in plastic, and uses a layer containing a highly permeable filler in a thermoplastic resin as the core layer. By integrally laminating a conductive thermoplastic resin on the substrate, and further laminating a thermoplastic resin on both or one side,
Due to the extremely large impedance mismatch effect between the highly permeable filler-containing thermoplastic resin layer and the conductive thermoplastic resin layer, by adding a small amount of the highly permeable filler or conductive filler, a good electromagnetic shielding effect and It has a sufficient shielding effect against low-impedance electromagnetic waves, stabilizes the extrusion of highly permeable fillers and conductive filler dispersion layers, and has excellent suitability for secondary processing, and also improves the mechanical strength of composite sheets.
The object of the present invention is to provide a composite plastic sheet that has excellent folding durability and impact resistance. That is, the present invention provides conductive fillers on both sides of the core layer of a thermoplastic resin film or sheet containing 6 to 40% by volume of a powdery and/or fibrous highly permeable filler with a relative magnetic permeability of 100 or more at 10 kHz. It is characterized by laminating an intermediate layer of thermoplastic resin film or sheet containing 6 to 40% by volume, and further laminating a thermoplastic resin film or sheet skin layer on one or both sides of the intermediate layer. The present invention will be explained in more detail below. As the thermoplastic resin for the skin layer used in the present invention, hard vinyl chloride resin, acrylic modified hard vinyl chloride resin, general styrene resin, impact-resistant styrene resin, vinyl aromatic compound, styrene, α
- Thermoplastic block copolymer resins such as methylstyrene and the conjugated diene is butadiene, isoprene, piperylene, etc. in a ratio of 75 to 95:35:5, as well as ABS resin, ethylene resin, ethylene-1-butene Random copolymer, ethylene-
Modified ethylene resins such as vinyl acetate copolymers and ethylene-acrylic acid ester copolymers, propylene resins, carbonate resins, poly(2,6 dimethylphenylene oxide) and modified PPO resins that are derivatives thereof, etc. can be used. . The thermoplastic resin used as the skin layer may be a single substance, and it is also necessary to match the extrusion flow characteristics with the conductive thermoplastic resin intermediate layer and the highly permeable filler-containing thermoplastic resin core layer, and to improve the performance of the composite plastic sheet. In order to improve it, it is also possible to use a mixture of two or more types of resins or to add an appropriate amount of additives. Furthermore, the intermediate layer made of the conductive thermoplastic resin of the present invention can have physical properties such as mechanical strength, rigidity, impact resistance, and bending strength due to the thermoplastic resin layer of the skin layer. Therefore, the conductive thermoplastic resin intermediate layer is not required to have the above-mentioned physical properties so strongly, and the fluidity during extrusion processing is determined by the thermoplastic resin of the skin layer and the thermoplastic resin containing a high magnetic permeability filler. It is important to improve the adhesion to the adhesive layer, or in the case of using an adhesive, or the adhesion with the thermoplastic resin skin layer and the thermoplastic resin core layer containing a highly permeable filler. For this purpose, the conductive thermoplastic intermediate layer is
Various thermoplastic resins similar to those for the skin layer can be used alone or as a mixture of two or more types, and additives can be used in appropriate amounts depending on the performance. Next, the core layer made of the thermoplastic resin containing a highly permeable filler of the present invention imparts physical properties such as mechanical strength, rigidity, impact resistance, and bending strength to the thermoplastic resin layer of the skin layer. Since the thermoplastic resin core layer containing a highly permeable filler is not required to have the above-mentioned physical properties, the fluidity during extrusion processing is not as strong as the conductive thermoplastic resin core layer. In the case of matching the layer, adhesion with the conductive thermoplastic resin intermediate layer, or using an adhesive,
It is important to improve the adhesion with the adhesive layer. For this purpose, the thermoplastic resin core layer containing a highly permeable filler is made of various thermoplastic resins similar to those used in the thermoplastic resin skin layer and the conductive thermoplastic resin intermediate layer, either alone or as a mixture of two or more types. ,
Appropriate amounts of additives can also be used depending on performance. The conductive filler used in the present invention includes (i) particulate carbon black, metal powder, graphite powder, and nickel-coated graphite powder (ii) flaky aluminum flakes and metal-plated mica (iii) fibrous carbon fiber, metal It is a metalized glass fiber whose surface is coated with aluminum, and it does not matter whether it is used alone or in combination of two or more types, but it is best to use carbon black and carbon fiber together. You can get results. The amount of conductive filler added is 6 to 40% by volume, preferably 10 to 30% by volume. If it is less than 6% by volume, almost no electromagnetic wave shielding effect will be obtained, and if it exceeds 40% by volume, extrusion processing will be difficult. This results in a significant decrease in property values such as mechanical strength, and insufficient suitability for secondary processing. The highly permeable filler used in the present invention is 10
Powdered and/or fibrous metals and/or metal oxides with a relative magnetic permeability of 100 or more in kilohertz, specifically powdered and/or fibrous supermalloy, super permalloy, permalloy, ferrite, pure Iron, silicon-iron alloy, copper-chromium-nickel-iron alloy, nickel, etc. are used, and among them, supermalloy, super permalloy, permalloy, ferrite, pure iron, and silicon-iron alloy give good effects. When the relative magnetic permeability is less than 100, the electromagnetic wave shielding effect decreases, and the shielding effect cannot be obtained unless the amount of filler is increased. The amount of high magnetic permeability filler added is 6 to 40% by volume, preferably 10 to 30% by volume. If it is less than 6% by volume, almost no electromagnetic wave shielding effect will be obtained, and if it exceeds 40% by volume, extrusion processing will be difficult. This results in a significant decrease in property values such as mechanical strength, and insufficient suitability for secondary processing. Next, in order to manufacture the product of the present invention, for example, a thermoplastic resin and a high magnetic permeability filler used for a thermoplastic resin core layer containing a highly magnetically permeable filler, and a thermoplastic resin and a conductive resin used for a conductive thermoplastic resin intermediate layer. Banbury mixer, co-kneader, and filler respectively.
The pellets are kneaded using a kneading machine such as an extruder, and then the resins of the thermoplastic resin skin layer, the conductive thermoplastic resin intermediate layer, and the thermoplastic resin core layer containing a highly permeable filler are mixed using three extruders. The thermoplastic resin skin layer, the conductive thermoplastic resin intermediate layer, and the highly permeable filler-containing thermoplastic resin core layer are extruded and laminated together using a five-layer die, or the thermoplastic resin is supplied using four extruders. The resins for the resin skin layer, the conductive thermoplastic resin intermediate layer, the highly permeable filler-containing thermoplastic resin core layer, and the adhesive layer are respectively supplied, and the thermoplastic resin skin layer and the conductive thermoplastic resin intermediate layer are supplied from a 7-layer die. The core layer of thermoplastic resin containing a highly permeable filler and the adhesive layer are laminated and integrated. Furthermore, in manufacturing the above-mentioned composite plastic sheet, the thermoplastic resin skin layer may be laminated on only one side of the conductive thermoplastic resin intermediate layer, and in this case, if the adhesive layer is not interposed, a 4-layer die is used. When using an adhesive layer, a 6-layer die is used. Furthermore, it is also possible to adopt a method in which each resin is supplied to an annular passage provided between the extruder cylinder section and a single-layer die, and after being laminated within the annular passage, the resins are extruded and integrated from the single-layer die. The overall wall thickness of the electromagnetic wave shielding composite plastic sheet of the present invention obtained by such a coextrusion method is about 0.2 to 10.0 mm, preferably about 0.5 to 6.0 mm, and if the wall thickness is less than 0.2 mm, When molded products such as electronic device casings are formed by compressed air or vacuum forming, physical properties such as mechanical strength, rigidity, impact resistance, and bending strength deteriorate. On the other hand, if the wall thickness exceeds 10.0 m/m, compressed air or vacuum forming becomes difficult. In addition, the wall thickness of the thermoplastic resin core layer containing high magnetic permeability filler is 2.5 of the total wall thickness.
~35%, preferably 5-25%, and the wall thickness is 2.5
If it is less than %, it becomes difficult to form a film during extrusion molding, and a sufficient electromagnetic wave shielding effect cannot be obtained. On the other hand, if the wall thickness exceeds 35%, air pressure or vacuum forming becomes difficult, and the physical properties such as mechanical strength of the molded product become insufficient. Further, the thickness of the conductive thermoplastic resin intermediate layer is 5 to 70%, preferably 10 to 50% of the total thickness,
If the wall thickness is less than 5%, it will be difficult to form a film during extrusion, and furthermore, the electromagnetic wave shielding effect will hardly be obtained. On the other hand, if the wall thickness exceeds 70%, air pressure or vacuum forming becomes difficult, and the physical properties such as mechanical strength of the molded product become insufficient. As explained above, the present invention provides a conductive thermoplastic resin intermediate layer containing a conductive filler on both sides of a high magnetic permeability filler-containing thermoplastic resin core layer, and furthermore, one or both of the conductive filler-containing thermoplastic resin intermediate layers. By creating a laminated sheet with a thermoplastic resin skin layer, the extrusion characteristics between each laminated resin are improved and the adhesion is also good. Furthermore, it has excellent secondary processability, and the sheet has excellent mechanical strength, folding durability, and impact resistance, and the presence of an electrical insulating layer has the effect of preventing electric shock accidents. The present invention will be described in more detail with reference to Examples. Examples 1 to 4 The impact-resistant styrene resin is “Denka Styrene HI”
-S-3: Denki Kagaku Kogyo Co., Ltd. trade name", ethylene -
The 1-butene random copolymer resin is “Tafmer A”.
-4085: Mitsui Petrochemical Co., Ltd. trade name" and the powdered ferrite is "BSF-547: Toda Kogyo Co., Ltd. trade name," and the composition shown in the table is used.
2.5 After kneading with a Banbury mixer, the mixture was made into pulverized particles using a pulverizer. In addition, the impact-resistant styrene resin is “Denka Styrene”.
HI-S-3: Denki Kagaku Kogyo Co., Ltd. trade name", ethylene-1-butene random copolymer resin "Tafmer A-4085: Mitsui Petrochemical Co., Ltd. trade name", carbon black "Vulcan XC-" 72: Kyabot Co., Ltd. trade name" and the brass fiber was "Aisin Metal Fiber: Aisin Seimitsu Co., Ltd. trade name", and the composition was as shown in the table. After kneading the mixture with a 2.5 Banbury mixer, It was made into pulverized particles using a pulverizer. Among the above-mentioned crushed grains, those mixed with ferrite powder are supplied into the extruder from the supply port of a 40 m/m extruder (L/D = 24), melted, and supplied to the center layer of a 5-layer sheet die. , carbon black and brass fibers are kneaded using a 50m/m extruder (L/D=
27) is fed into the extruder from the supply port, melted and
The two middle layers of the layer sheet die were fed. On the other hand, an impact-resistant styrene resin was supplied to the extruder from the supply port of a 65 mmφ extruder (L/D=25), melted, and supplied to the two skin layers of the five-layer sheet. The die has multiple manifolds, and after exiting the manifold, the resins collide with each other in front of the lip. The width of the die was adjusted to 600 m/m, and the lip was adjusted to 6.0 m/m. As a result, the core layer was a highly permeable filler-containing thermoplastic resin layer of 1.0 m/m, and the middle layer was a conductive thermoplastic resin layer of 1.0 m/m each. A five-layer sheet having a total thickness of 5.0 m/m and a surface layer of impact-resistant styrene resin layer of 1.0 m/m and a total thickness of 5.0 m/m was obtained. The resulting five-layer sheet had sufficient adhesion between each layer and was impossible to peel off. As shown in the table, this sheet has an electromagnetic shielding effect,
Both were excellent in performance such as mechanical strength and mechanical strength. Furthermore, when this sheet was formed into a housing shape by pressure forming, a molded product with excellent rigidity and impact resistance was obtained while sufficiently maintaining the electromagnetic wave shielding effect. Example 5 Impact-resistant water lily resin and ethylene of Example 1
Instead of 1-butene random copolymer resin,
The same operation as in Example 1 was performed except that the ABS resin "Decan ABS GR-2000: trade name of Denki Kagaku Kogyo Co., Ltd." was used. As shown in the table, the physical properties measurement results were excellent in performance such as electromagnetic wave shielding effect and mechanical strength. Example 6 Instead of the brass fiber of Example 1, carbon fiber “Besphite HTA-C6S: Toho Rayon Co., Ltd. trade name” was used.
The same operation as in Example 1 was performed except that . As shown in the table, the physical properties measurement results were excellent in performance such as electromagnetic wave shielding effect and mechanical strength. Comparative Examples 1 to 4 Under the same conditions as Example 1, except that a highly permeable filler or a conductive filler was added in an amount exceeding the upper limit of the claimed range and an amount less than the lower limit,
A sheet with a wall thickness of 5.0 mm was obtained. If the highly permeable filler or conductive filler is added in excess, the plastic sheet will lose its mechanical strength, and if it is insufficient, the electromagnetic wave shielding effect will not be obtained. Comparative Examples 5 to 6 Example 1 except that brass fiber "Aisin Metal Fiber: trade name of Aisin Seiki Co., Ltd." and nickel powder "Fukuda Metal Foil Powder Kogyo Co., Ltd." were used as fillers for the middle core layer. It had a similar composition. The results are shown in the table. Compared to Example 1, the electromagnetic wave shielding effect is reduced.
【表】【table】
Claims (1)
末状及び／又は繊維状高透磁性フイラーを６〜40
容量％含有する熱可塑性樹脂フイルム又はシート
の中芯層の両面に導電性フイラーを６〜40容量％
含有する熱可塑性樹脂フイルム又はシートの中間
層を積層し、更に該中間層の片面又は両面に熱可
塑性樹脂フイルム又はシートの表皮層を積層して
なる電磁波遮蔽性複合プラスチツクシート。1 Powdered and/or fibrous high permeability filler with a relative magnetic permeability of 100 or more at 10 kilohertz from 6 to 40
6 to 40% by volume of conductive filler on both sides of the core layer of thermoplastic resin film or sheet containing 6% to 40% by volume
An electromagnetic wave-shielding composite plastic sheet comprising a thermoplastic resin film or sheet containing an intermediate layer laminated thereon, and a thermoplastic resin film or sheet skin layer laminated on one or both sides of the intermediate layer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59004521A JPS60148195A (en) | 1984-01-13 | 1984-01-13 | Electromagnetic shielding composite plastic sheet |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59004521A JPS60148195A (en) | 1984-01-13 | 1984-01-13 | Electromagnetic shielding composite plastic sheet |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS60148195A JPS60148195A (en) | 1985-08-05 |
| JPH0570959B2 true JPH0570959B2 (en) | 1993-10-06 |
Family
ID=11586350
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP59004521A Granted JPS60148195A (en) | 1984-01-13 | 1984-01-13 | Electromagnetic shielding composite plastic sheet |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS60148195A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2518626B2 (en) * | 1986-10-15 | 1996-07-24 | 呉羽化学工業株式会社 | Electromagnetic wave shielding sheet and manufacturing method thereof |
| CA2080177C (en) * | 1992-01-02 | 1997-02-25 | Edward Allan Highum | Electro-magnetic shield and method for making the same |
| JP3224936B2 (en) * | 1994-03-03 | 2001-11-05 | 日本シイエムケイ株式会社 | Printed wiring board material containing magnetic material in insulating layer |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS54124298A (en) * | 1978-03-20 | 1979-09-27 | Tdk Corp | Material for radio wave absorber |
| JPS58173898A (en) * | 1982-04-05 | 1983-10-12 | 日本電気株式会社 | Radio wave absorber |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0225280Y2 (en) * | 1980-10-01 | 1990-07-11 |
-
1984
- 1984-01-13 JP JP59004521A patent/JPS60148195A/en active Granted
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS54124298A (en) * | 1978-03-20 | 1979-09-27 | Tdk Corp | Material for radio wave absorber |
| JPS58173898A (en) * | 1982-04-05 | 1983-10-12 | 日本電気株式会社 | Radio wave absorber |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS60148195A (en) | 1985-08-05 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Huang et al. | Studies on the influence of double-layer electroless metal deposition on the electromagnetic interference shielding effectiveness of carbon fiber/ABS composites | |
| JPS59152936A (en) | Hybrid resin composition having excellent electromagnetic shielding property and rigidity | |
| JPH0570959B2 (en) | ||
| JPH0417777B2 (en) | ||
| JPS6013516A (en) | Manufacture of multilayer injection molded product with electromagnetic shielding property | |
| JPH09116293A (en) | Electromagnetic wave shielding material, its manufacture, and its application method | |
| JPS58127743A (en) | Thermoplastic resin composition | |
| JPS60177699A (en) | Method of producing electromagnetic wave shielding housing | |
| JPS59210957A (en) | Electrically conductive plastic film or sheet | |
| JP2000244167A (en) | Electromagnetic-wave-disturbance preventive material | |
| JPS5920662A (en) | Composite plastic sheet | |
| KR100466134B1 (en) | Electromagnetic Shielding Resin Composition | |
| JPS5986638A (en) | Resin composition having excellent electromagnetic wave shielding property and rigidity | |
| JP2009125974A (en) | Flame retardant laminated sheet | |
| JPH048224B2 (en) | ||
| JPS60176300A (en) | Method of producing electromagnetic wave shielding housing | |
| JPS60201697A (en) | Electromagnetic wave shielding conductive plastic film or sheet | |
| JPS6042899A (en) | Method of producing electromagnetic wave shielding multilayer molded part | |
| JP4381871B2 (en) | Electromagnetic wave noise suppressing body, manufacturing method thereof, and printed wiring board with electromagnetic wave noise suppressing function | |
| JPH0322904B2 (en) | ||
| JPS5996148A (en) | Ethylene copolymer composition | |
| JPH0435920B2 (en) | ||
| JPS6076542A (en) | Electrically conductive resin | |
| JPS58222144A (en) | Thermoplastic resin composition | |
| CN1215303A (en) | Radio telephone electromagnetic radiation shielding cover and its production method |