JPH0451574B2 - - Google Patents
Info
- Publication number
- JPH0451574B2 JPH0451574B2 JP62228182A JP22818287A JPH0451574B2 JP H0451574 B2 JPH0451574 B2 JP H0451574B2 JP 62228182 A JP62228182 A JP 62228182A JP 22818287 A JP22818287 A JP 22818287A JP H0451574 B2 JPH0451574 B2 JP H0451574B2
- Authority
- JP
- Japan
- Prior art keywords
- foam
- resin
- weight
- parts
- open
- 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
- 239000006260 foam Substances 0.000 claims description 118
- 229920005989 resin Polymers 0.000 claims description 61
- 239000011347 resin Substances 0.000 claims description 61
- 238000004781 supercooling Methods 0.000 claims description 16
- 229920005672 polyolefin resin Polymers 0.000 claims description 13
- 229920001748 polybutylene Polymers 0.000 claims description 12
- 238000004519 manufacturing process Methods 0.000 claims description 11
- 238000000034 method Methods 0.000 claims description 11
- 239000000203 mixture Substances 0.000 claims description 8
- 239000004604 Blowing Agent Substances 0.000 claims description 6
- 229920012753 Ethylene Ionomers Polymers 0.000 claims description 6
- 238000004898 kneading Methods 0.000 claims description 3
- 238000000113 differential scanning calorimetry Methods 0.000 claims 4
- 238000005187 foaming Methods 0.000 description 31
- 230000000052 comparative effect Effects 0.000 description 19
- 210000004027 cell Anatomy 0.000 description 16
- 239000000463 material Substances 0.000 description 16
- 230000035699 permeability Effects 0.000 description 14
- 238000011156 evaluation Methods 0.000 description 13
- JOYRKODLDBILNP-UHFFFAOYSA-N Ethyl urethane Chemical compound CCOC(N)=O JOYRKODLDBILNP-UHFFFAOYSA-N 0.000 description 10
- 229920000554 ionomer Polymers 0.000 description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 10
- 239000004088 foaming agent Substances 0.000 description 9
- 229920000642 polymer Polymers 0.000 description 9
- 239000000126 substance Substances 0.000 description 9
- 230000008859 change Effects 0.000 description 8
- 238000009826 distribution Methods 0.000 description 7
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- 238000002844 melting Methods 0.000 description 7
- 230000008018 melting Effects 0.000 description 7
- 230000000694 effects Effects 0.000 description 6
- 238000011084 recovery Methods 0.000 description 6
- 239000000454 talc Substances 0.000 description 6
- 229910052623 talc Inorganic materials 0.000 description 6
- 239000011358 absorbing material Substances 0.000 description 5
- 239000002585 base Substances 0.000 description 5
- 230000000903 blocking effect Effects 0.000 description 5
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- DDMOUSALMHHKOS-UHFFFAOYSA-N 1,2-dichloro-1,1,2,2-tetrafluoroethane Chemical compound FC(F)(Cl)C(F)(F)Cl DDMOUSALMHHKOS-UHFFFAOYSA-N 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 4
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- 239000012528 membrane Substances 0.000 description 4
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- 230000003068 static effect Effects 0.000 description 4
- 238000004383 yellowing Methods 0.000 description 4
- YMWUJEATGCHHMB-UHFFFAOYSA-N Dichloromethane Chemical compound ClCCl YMWUJEATGCHHMB-UHFFFAOYSA-N 0.000 description 3
- 239000004743 Polypropylene Substances 0.000 description 3
- 239000000853 adhesive Substances 0.000 description 3
- 230000001070 adhesive effect Effects 0.000 description 3
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 3
- 238000012669 compression test Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 239000012530 fluid Substances 0.000 description 3
- 229920001903 high density polyethylene Polymers 0.000 description 3
- 239000004700 high-density polyethylene Substances 0.000 description 3
- 229920001684 low density polyethylene Polymers 0.000 description 3
- 239000004702 low-density polyethylene Substances 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 3
- OFBQJSOFQDEBGM-UHFFFAOYSA-N n-pentane Natural products CCCCC OFBQJSOFQDEBGM-UHFFFAOYSA-N 0.000 description 3
- 229920001200 poly(ethylene-vinyl acetate) Polymers 0.000 description 3
- 229920001155 polypropylene Polymers 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 229920003002 synthetic resin Polymers 0.000 description 3
- 239000000057 synthetic resin Substances 0.000 description 3
- 239000011800 void material Substances 0.000 description 3
- IBXNCJKFFQIKKY-UHFFFAOYSA-N 1-pentyne Chemical compound CCCC#C IBXNCJKFFQIKKY-UHFFFAOYSA-N 0.000 description 2
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- 239000004338 Dichlorodifluoromethane Substances 0.000 description 2
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 2
- 239000005977 Ethylene Substances 0.000 description 2
- 239000004372 Polyvinyl alcohol Substances 0.000 description 2
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 2
- UIIMBOGNXHQVGW-UHFFFAOYSA-M Sodium bicarbonate Chemical compound [Na+].OC([O-])=O UIIMBOGNXHQVGW-UHFFFAOYSA-M 0.000 description 2
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 230000003139 buffering effect Effects 0.000 description 2
- 210000000170 cell membrane Anatomy 0.000 description 2
- 238000002425 crystallisation Methods 0.000 description 2
- 230000008025 crystallization Effects 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- PXBRQCKWGAHEHS-UHFFFAOYSA-N dichlorodifluoromethane Chemical compound FC(F)(Cl)Cl PXBRQCKWGAHEHS-UHFFFAOYSA-N 0.000 description 2
- 235000019404 dichlorodifluoromethane Nutrition 0.000 description 2
- 239000005038 ethylene vinyl acetate Substances 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- NNPPMTNAJDCUHE-UHFFFAOYSA-N isobutane Chemical compound CC(C)C NNPPMTNAJDCUHE-UHFFFAOYSA-N 0.000 description 2
- 229920002589 poly(vinylethylene) polymer Polymers 0.000 description 2
- 229920002451 polyvinyl alcohol Polymers 0.000 description 2
- 238000005070 sampling Methods 0.000 description 2
- CYRMSUTZVYGINF-UHFFFAOYSA-N trichlorofluoromethane Chemical compound FC(Cl)(Cl)Cl CYRMSUTZVYGINF-UHFFFAOYSA-N 0.000 description 2
- 229940029284 trichlorofluoromethane Drugs 0.000 description 2
- NPNPZTNLOVBDOC-UHFFFAOYSA-N 1,1-difluoroethane Chemical compound CC(F)F NPNPZTNLOVBDOC-UHFFFAOYSA-N 0.000 description 1
- 229940051271 1,1-difluoroethane Drugs 0.000 description 1
- RFCAUADVODFSLZ-UHFFFAOYSA-N 1-Chloro-1,1,2,2,2-pentafluoroethane Chemical compound FC(F)(F)C(F)(F)Cl RFCAUADVODFSLZ-UHFFFAOYSA-N 0.000 description 1
- BHNZEZWIUMJCGF-UHFFFAOYSA-N 1-chloro-1,1-difluoroethane Chemical compound CC(F)(F)Cl BHNZEZWIUMJCGF-UHFFFAOYSA-N 0.000 description 1
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 description 1
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 1
- VOPWNXZWBYDODV-UHFFFAOYSA-N Chlorodifluoromethane Chemical compound FC(F)Cl VOPWNXZWBYDODV-UHFFFAOYSA-N 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000000872 buffer Substances 0.000 description 1
- 239000001273 butane Substances 0.000 description 1
- CQEYYJKEWSMYFG-UHFFFAOYSA-N butyl acrylate Chemical group CCCCOC(=O)C=C CQEYYJKEWSMYFG-UHFFFAOYSA-N 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- 239000000378 calcium silicate Substances 0.000 description 1
- 229910052918 calcium silicate Inorganic materials 0.000 description 1
- OYACROKNLOSFPA-UHFFFAOYSA-N calcium;dioxido(oxo)silane Chemical compound [Ca+2].[O-][Si]([O-])=O OYACROKNLOSFPA-UHFFFAOYSA-N 0.000 description 1
- 210000002390 cell membrane structure Anatomy 0.000 description 1
- NEHMKBQYUWJMIP-NJFSPNSNSA-N chloro(114C)methane Chemical compound [14CH3]Cl NEHMKBQYUWJMIP-NJFSPNSNSA-N 0.000 description 1
- 235000019406 chloropentafluoroethane Nutrition 0.000 description 1
- AFYPFACVUDMOHA-UHFFFAOYSA-N chlorotrifluoromethane Chemical compound FC(F)(F)Cl AFYPFACVUDMOHA-UHFFFAOYSA-N 0.000 description 1
- 229960004106 citric acid Drugs 0.000 description 1
- 239000011538 cleaning material Substances 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 239000002537 cosmetic Substances 0.000 description 1
- 238000004132 cross linking Methods 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 230000006378 damage Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- UMNKXPULIDJLSU-UHFFFAOYSA-N dichlorofluoromethane Chemical compound FC(Cl)Cl UMNKXPULIDJLSU-UHFFFAOYSA-N 0.000 description 1
- 229940099364 dichlorofluoromethane Drugs 0.000 description 1
- 238000000635 electron micrograph Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000006261 foam material Substances 0.000 description 1
- 150000008282 halocarbons Chemical class 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000007731 hot pressing Methods 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 239000003112 inhibitor Substances 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 1
- 239000001282 iso-butane Substances 0.000 description 1
- 239000000314 lubricant Substances 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229940073584 methylene chloride Drugs 0.000 description 1
- IJDNQMDRQITEOD-UHFFFAOYSA-N n-butane Chemical compound CCCC IJDNQMDRQITEOD-UHFFFAOYSA-N 0.000 description 1
- 239000002667 nucleating agent Substances 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 229920001083 polybutene Polymers 0.000 description 1
- 238000012805 post-processing Methods 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 230000003449 preventive effect Effects 0.000 description 1
- 239000001294 propane Substances 0.000 description 1
- 239000011342 resin composition Substances 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 239000000344 soap Substances 0.000 description 1
- 229910000030 sodium bicarbonate Inorganic materials 0.000 description 1
- 235000017557 sodium bicarbonate Nutrition 0.000 description 1
- 239000003381 stabilizer Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 229920001169 thermoplastic Polymers 0.000 description 1
- 239000004416 thermosoftening plastic Substances 0.000 description 1
- 238000009423 ventilation Methods 0.000 description 1
- 235000012431 wafers Nutrition 0.000 description 1
- 239000011787 zinc oxide Substances 0.000 description 1
- XOOUIPVCVHRTMJ-UHFFFAOYSA-L zinc stearate Chemical compound [Zn+2].CCCCCCCCCCCCCCCCCC([O-])=O.CCCCCCCCCCCCCCCCCC([O-])=O XOOUIPVCVHRTMJ-UHFFFAOYSA-L 0.000 description 1
Description
〔産業上の利用分野〕
本発明は、ポリオレフイン系樹脂の連続気泡発
泡体とその製造方法との改良技術に関し、例えば
緩衝材としての利用分野では、軟質ウレタンフオ
ームに匹敵する高度の緩衝性能を経済的かつ有益
に発揮させることが可能なポリオレフイン系樹脂
連続気泡発泡体とその製造方法に関する。
〔従来の技術〕
従来、合成樹脂の連続気泡(連通気泡とも云
う)の発泡体としては軟質ウレタンフオームがよ
く知られている。このものは柔軟で加工性がよ
く、しかも比較的安価に供給できるために、例え
ば洗浄用材、濾過材、吸音材、吸水材、緩衝材、
緩衝保護材等の幅広い分野で大量に使用されてい
る。殊に、コンピユータのフロツピイデイスス装
置等の許容衝撃性の低い被包装体用の緩衝材分野
では低い静的応力の領域で低い値の最大減速度
(低G値)が取り出せる所謂「高度の緩衝性能を
持つ緩衝材」としてのウレタンフオームの市場性
は、独占的と言えるものになつている。
一方、ポリオレフイン系樹脂を上記連続気泡の
発泡体分野に活用させる試みも古い。このものは
ポリオレフイン樹脂自体の持つ優れた特性、即ち
例えば耐酸、耐アルカリ等の耐薬品性、耐熱、耐
水、耐候等の耐久・堅牢性等がその連通気泡体に
付与されるならば、これらの耐久・堅牢性に欠け
る軟質ウレタンフオームに取つて代わることが可
能となり、そこにポリオレフイン系樹脂発泡体の
一大市場分野が形成されると考えられるからであ
る。
しかしながら、現状は中々そうはならないので
ある。その原因は次の点にあると言われている。
〔発明が解決しようとする課題〕
即ち、一般にポリオレフイン系樹脂は、揮発性
発泡材との相溶性に乏しく、又、ガス体としての
保持性に乏しい。その上溶融時の流動粘弾性は発
泡適性温度の近傍において急激に変化する性質を
有する。従つて、これを押出発泡に供しようとす
る時は、発泡剤を樹脂内により多く相溶分散さ
せ、かつ発泡が生じない圧力状態に維持させてお
き度い押出機内の加圧加熱条件と、押出直後に樹
脂の流動配向が生じ多次元の発泡膨脹が生じ易い
押出条件との調和が図れず、押出機設備能力を大
幅に下回る小断面積の発泡体になつてしまう現象
が生じたり、押出発泡時の発泡剤の揮発逸散が激
しくて気泡化(低密度化)が進行せず、かつ収縮
変形の著しい発泡体にしかならなかつたり、独立
気泡体形成温度より高温側に当たる連続気泡の形
成温度領域では、樹脂の粘弾性の低下が急激に進
行して、気泡の連通化と気泡の破壊や発泡体内部
での空洞化(ブローホールの形成)現象とが同時
に生じてしまうことになつて、不均一でかつ緩衝
性能の悪い発泡体にしかならない原因が本質的に
存在していることに由来する。
これらの改良策として基材樹脂を変更するとい
う観点からは、エチレン系イオノマー樹脂の単体
を用いる提案(特公昭58−41297号公報)、ポリプ
ロピレン樹脂に1,2−ポリブタジエン樹脂を混
合したものを用いる提案(特開昭56−60233号公
報)、低密度ポリエチレン、高密度ポリエチレン
及びエチレン酢酸ビニル共重合体等のポリオレフ
イン樹脂に、各々エチレン系イオノマー樹脂を混
合した樹脂を用いる提案(特開昭59−194820号公
報)並びにエチレン系イオノマー樹脂を押出機内
で金属架橋させながら、これに十分発泡剤を溶解
させて発泡に供する提案(特開昭46−48145号公
報)等がある。
これらの提案は、概して200cm2程度の断面積の
発泡体が得られる程度には改善されているが、そ
の断面積の発泡体を得る上での空洞性(ブローホ
ールの度合)、繰り返しの圧縮強度、通気性(緩
衝性に関する特性)、密度分布、寸法変化及びそ
のものの(押出発泡の)生産性等から総合的に評
価する時は、未だ市場要求を満たす経済性及び品
質水準の発泡体には程遠いし、発泡体の断面積を
経済的に更に大きくし度いと云う観点からも、満
足できる水準のものではないと云う問題点を有し
ている(第1表の結果参照)。
換言すれば、ポリオレフイン系樹脂の連続気泡
発泡体の技術水準は、まだ第1表に示す程度であ
るため「高度の緩衝性能を持つ緩衝材」が必要な
包装の分野では、軟質ウレタンフオームがそれな
りの欠点を有しているにもかかわらず、独占的な
地位を保つ背景になつている。
かかる観点に立つて本発明の目的は、ブローホ
ールのない、通気性、密度分布の均一性、繰り返
しの圧縮強度に優れ、寸法変化の少ない所謂軟質
ウレタン連続気泡発泡体の緩衝性能に近い性能を
備え、かつ耐候性、耐薬品性、耐水性、熱接着性
及び熱成形性を有するポリオレフイン系樹脂の連
続気泡発泡体として、経済性を満たす状態(大断
面積のものが生産性良く確保できる状態)で提供
できるようにすることにある。
〔課題を解決するための手段〕
本発明の第1発明(発泡体)、第2発明(製造
法)の双方に共通する構成上の主要部は、
(イ) 使用する基材樹脂は、ポリブテン−1樹脂
〔A〕 100重量部とエチレン系イオノマー樹脂
〔B〕 10〜100重量部との混合樹脂であり、その
ポリブテン−1樹脂〔A〕はD.S.C.で測つた
過冷却度が20〜70℃の値の範囲である、
(ロ) 対象の発泡体は、その断面積が150cm2以上の
均質な気泡構造を有する連続気泡発泡体であ
る、
の(イ)、(ロ)の組合せにある。
以下に本発明を表及び図面を併用して詳述す
る。発明内容の理解を深める意味からまず発泡体
の製造方法について説明する。
第1表(実施例1、比較例1〜7に対応)は、
本発明の基材樹脂種を選ぶことについて、従来技
術のそれと対比する形で本発明の内容を具体的に
説明しようとしたものである。即ち、第1表の評
価項目b〜gは断面積が300cm2、目標密度30Kg/
m3の水準のものを得ようとした時の空洞性(ブロ
ーホールの発生)、通気性、密度分布、寸法変化、
繰り返し圧縮強度と言つた得られる発泡体の品質
及びその発泡体の生産性について評価したもので
ある。又、第1表a項は、発泡体の断面積を更に
大きなものにできる可能性の程度を評価したもの
である。この第1表のa〜g項の結果によると、
本発明の目的を達成し得る発泡体の製造方法は、
発泡に供する基材樹脂そのものに、本発明特有の
ポリブテン−1樹脂〔A〕と、エチレン系イオノ
マー樹脂〔B〕との混合樹脂を採用することであ
る。それは樹脂〔A〕を例えばポリプロピレン樹
脂、低・高密度ポリエチレン或いはエチレン酢酸
ビニル共重合体に置き換えたりすると、例えば空
洞性(ブローホールの発生)が著しく、反面、通
気性が悪化して緩衝性能の良い発泡体が得られな
い。又〔A〕樹脂が単独の場合は、断面倍率を大
きくでき、〔B〕樹脂が単独の場合は、空洞性を
抑制できる利点を示すが、〔A〕、〔B〕の各々は
共に通気性に乏しく生産性にも今一つ十分な結果
が得られない(比較例6、7参照)。
これらの関係において、〔A〕、〔B〕樹脂を混
合することで達成される本発明の製法上の改善効
果は、本発明者らによつて初めて究明された現象
で、連続気泡にするのに適した流動粘弾特性に改
質されるこることに由来する現象と推察される。
即ち、ポリオレフイン系樹脂の押出発泡での連
続気泡の製造方法は、独立気泡の場合の発泡温度
条件に比べて約2〜6℃高温側に設定される。こ
の際、流動状態の樹脂粘度は、気泡の相互が合併
し、気泡数を減じて大寸法の気泡にならないよう
に、かつ穴の開いた気泡膜が多数形成されて固化
し、連続した気泡の割合が多くなる状態に維持さ
れることを要するが、〔A〕+〔B〕からなる混合
樹脂は上記発泡適性温度領域での樹脂粘度変化の
温度依存性が小さく、従つて調整温度範囲が拡大
されるために、上記状態の維持が容易となるもの
と推定される。又、本発明では、この流動粘弾性
の状態を押出が安定して容易な無架橋状態の樹脂
のままで確保できる点に大きな利点がある。
第2表(実施例2〜5、比較例8、9に対応)
は、本発明で云う混合樹脂〔A〕、〔B〕の、その
成分割合が及ぼす効果への影響を明らかにした結
果の表である。第2表の結果によると、〔B〕樹
脂を混合することの効力は〔A〕樹脂100重量部
に対し少なくとも10重量部以上の量は必要である
が、100重量部では混合効力の上限に達してしま
う状態がよくわかる。本発明の〔A〕樹脂と
〔B〕樹脂を混合することで得られる相互の改良
効果は〔A〕樹脂100重量部に対して〔B〕樹脂
は30〜60重量部の範囲になるよう調整することが
望ましいと言える。
第3表(実施6〜8及び比較例10、11に対応)
は、発泡体の製造方法の生産性上の別の側面、即
ち生産された発泡板の多数を積み重ねて貯蔵しよ
うとする時、発泡板の重なり面が粘着(ブロツキ
ング)し、個々の発泡板として扱い難くなる問題
点への対策(耐ブロツキング性)、出来上がつた
発泡板を所定の形状サイズに切断・切削加工した
時に加工面が凹凸化(或いは粗面化)して商品価
値を減じてしまうことへの対策(耐加工粗面性)
或いは所定の形状サイズの型刃で打抜き加工する
時の発泡体の圧縮に対する回復性と云う三つの面
の総合から、発泡体の後加工適性を評価したもの
である。
この側面は、発泡体を構成するポリブテン−1
樹脂の持つ「過冷却度」の程度を選ぶことで調整
できるが、第3表の結果によると「過冷却度」の
10〜90℃の範囲、更には20〜70℃の範囲にあるも
のを選ぶことが望ましいことが示されるている。
次に、本発明の連続気泡発泡体について述べ
る。
本発明の発泡体は、上記した製造方法によつて
得られる関係で、基材樹脂が〔A〕+〔B〕の混合
樹脂の〔A〕100重量部:〔B〕100〜10重量部の
割合の、樹脂〔A〕のD.S.C.で測つた過冷却度が
20〜70℃の連続気泡構造の発泡体である。
第1,2図は気泡膜に形成された穴の形状を示
すセル膜の構造写真(20倍の電子顕微鏡による)
で第1図は本発明のもの、第2図は比較品で
〔B〕樹脂単品のものを示す。
第1図における本発明の特色は、気泡膜に穿が
たれている穴の形状分布が、比較品は比較的単純
な形のものが散在している状態であるのに対し、
本発明品は残つた気泡膜が網目様になるように小
さな穴が多数穿たれて穴開口部を大きくしている
形状構造をなしている。この相違は通気性におい
て、本発明(第1図)のものが良く(通気抵抗は
低く)、比較品(第2図)のものは悪い(通気抵
抗が高い)。軟質合成樹脂発泡体に高度な緩衝性
能を発揮させようとする時、その妨げとなる大き
な因子は発泡体内で閉鎖密封されている気体の存
在である。このものは押圧変形量に比例した反撥
力を衝撃として被包装物に与えることになるから
である。
本発明で評価されている通気性の良さ(通気抵
抗の低さ)は、発泡体に押圧変形力が加わつた
時、その変形量に見合う発泡体内の気体を迅速に
排出できる能力を示している。よつて、これに気
泡膜の強靭さや弾性の働きを示す繰り返しの回復
力が加われば、良質の緩衝材になる筈である。本
発明(第1図)の発泡体では、網目状に残された
気泡膜壁が上記の繰り返しの回復力を与え、開口
面積の大きい穴は通気性を与えることになるの
で、理想的な緩衝能を発揮できる。
第3図は市販品との緩衝性能の比較図で、Aは
本発明の発泡体(実施例1のもの)、Bは軟質ウ
レタンフオーム、Cはポリビニルアルコールフオ
ームを示す。図中、横軸は静的応力(Kg/cm2)、
縦軸は最大減速度(G)を表している。
第3図の結果によると、本発明の発泡体は静的
応力が約0.02〜0.03Kg/cm2の低応力側で、最大減
速度約32Gである低いG値の緩衝性能が取り出せ
ることを示している。この緩衝性能は軟質ウレタ
ンフオームの性能に匹敵するものである。
第4表(実施例9、比較例12、13に対応)は、
上記A、B、Cの発泡体について上記緩衝性の他
に耐候性、耐薬品性、耐水性、耐熱性、熱成形性
についても評価し、総合的な観点から対比した実
験結果表である。
第4表の結果によると、本発明の発泡体は、耐
候性、耐薬品性、耐水性、熱接着性及び熱成形性
のすべてにおいて軟質ウレタンフオームより優れ
総合的に調和のとれた優秀な発泡体であると言え
る。
殊に耐候性、耐水性が備わつた点は屋外での有
用性を、耐薬品性が加わつた点は工業資材、医薬
材用途への有用性を、熱接着性、熱成形性が揃つ
た点は、継ぎ合わせ、重ね合わせによる大面積
化、厚肉化の加工及び形に添わせる賦形加工等と
して使い易くする有用性を共に高めるものとして
注目できる。具体的には、例えば、フイルター、
吸音材、吸水材、吸油材、湿度センサー、おむつ
カバー、目地材、女性用生理用品及びシユーズ、
足袋などの緩衝材、日用品雑貨、各種ケースの緩
衝材などの用途に用いられる。特に、圧縮強度が
低く緩衝性能も優れているため、シリコンウエハ
ーやフロツピイデイスク装置のような軽くて壊れ
易い製品を保護するのに極めて適した性能を有す
る緩衝材となるのである。
本発明で使用される発泡剤としては、通常の揮
発性発泡剤が用いられる。代表的なものとしてプ
ロパン、ブタン、ペンタン、ペンチン、ヘキサン
等の低級炭化水素、メチレンクロライド、塩化メ
チル、トリクロロモノフルオロメタン、ジクロロ
モノフルオロメタン、モノクロロジフルオロメタ
ン、モノクロロトリフルオロメタン、ジクロロジ
フルオロメタン、1,1−ジフルオロエタン、1
−クロロ−1,1−ジフルオロエタン、1,2−
ジクロロテトラフルオロエタン、モノクロロペン
タフルオロエタン等のハロゲン化炭化水素があ
る。又、これらの混合物も有用である。又、発泡
剤の量としてはポリブテン−1とイオノマーとの
混合樹脂100重量部に対し通常は5〜50重量部で
ある。
本発明の連続気泡発泡体の製造には、公知の押
出発泡装置と同様の装置を使用できる。これは、
上記樹脂組成物に発泡剤を混合或いは押出機途中
から注入し、高温高圧下で混練溶融し低圧帯域に
連続押出発泡させる方法等が挙げられる。又、潤
滑剤、気泡調整剤としてステアリン酸亜鉛のよう
な金属石鹸、珪酸カルシウム、タルク、炭酸カル
シウム等の無機物微粉末を少量含有することがで
きる。又、場合によつては紫外線劣化防止剤、酸
化安定剤、着色剤等の添加も可能である。更に発
泡体の物性を改良する目的で連続気泡を形成する
のに妨げとならない熱可塑性合成樹脂を添加する
ことができる。
次に本発明で用いる特性の測定方法について述
べる。
(1) ポリマーの過冷却度
D.S.C.(パーキンエルマー社製IB型)を使用
し、10℃/minで融解させた場合のピーク温度
(融点=Tm℃)と、10℃/minで冷却し、接線
法で求めた結晶化が開始する温度(結晶化開始
温度=Tc℃)との差を表す(過冷却度=Tm
−Tc)。
(2) 発泡体を構成するポリブテン−1樹脂の過冷
却度
発泡体を熱プレスによりシート化したものに
ついて(1)で述べた方法により融点及び結晶化開
始温度の測定を行う。
第4図に示す通り、融点の高い方(T2)と
結晶化開始温度の高い方(T3)との差を発泡
体を構成するポリブテン−1樹脂の過冷却度と
する。
(3) ポリマーのM.I.
ASTM−D−1238−70、条件D(測定温度
190℃、荷重2.16Kg)により求めた。
(4) ポリマーの密度
ASTM−D−1505により求めた。
(5) 発泡体の連続気泡率
東芝ベツクマン社製のエアーピクノメータ
(モデル930)を使用し、ASTM−D−2856に
準じ求めた。
(6) 発泡体の断面積
安定して製造されたサンプルを1m毎に5か
所切断し、切断面にインクを付着させ、白紙に
写し取る。写し取つたものの断面積をプラニメ
ータにより測定する。5か所の平均値を発泡体
の断面積とする。
(7) 発泡体の空洞部面積
(6)と同様の方法で断面を写し取り、その中に
ある面積25mm2以上の空洞部について面積を測定
し各断面毎の空洞部面積を積算する。5か所の
平均値を採用する。
(8) 発泡体の気泡径
ISO NG/10N 159に記載の方法により、30
mmの直線を横切る気泡数より算出する。
(9) 発泡体の通気抵抗
ASTM−D−1564に記載の方法に準じサン
プル形状50mm厚×150mm幅×150mm長さのもの
を、140mm×140mmの開口部を持つチヤンバー上
に載せ、流量150/minで吸引した場合のチ
ヤンバー内圧力を測定する。
(10) 発泡体の密度
JIS−K−6767に記載の方法に準じて測定す
る。
(11) 発泡体の圧縮試験
JIS−K−6767に記載の方法に準じて測定す
る。
(12) 発泡体の圧縮残留歪
上記圧縮試験において、80%圧縮後除荷した
後応力を示さなくなつた時点での歪を測定す
る。
以下本発明で用いる評価方法と評価尺度につい
て述べる。
なお、下記項目の(B)〜(G)は採取する発泡体の断
面積が約300cm2(約70mm厚×400mm幅)及び発泡体
の平均密度を30Kg/m3に揃えたものについての評
価である。
(A) 断面倍率:採取する発泡体の平均気泡径を
1.0mmに揃え、ダイ内で発泡しない限界まで押
出量を低下した剪断速度で発泡させた場合にお
ける断面倍率により評価した〔断面倍率=(発
泡体の断面積÷ダイ開孔部面積)×100〕。
(尺度)
40以上 ◎
30を超え40未満 ○
30未満 ×
〔この値が大きい方が小さな押出機でも大きな
断面の製品がとれ、作業効率上及びエネルギー
的にも有利である。〕
(B) 空洞性:発泡体の断面積に占める空洞部の面
積割合である空洞率により評価した〔空洞率=
(空洞部面積÷断面積)×100〕。
(尺度)
5%未満 ◎
5%以上10%未満 ○
10%以上 ×
〔この値は小さい方が圧縮強度や緩衝性能のバ
ラツキが小さく、物性への信頼性が高い製品が
得られる。〕
(C) 通気性:発泡体中央部の中心部においてサン
プリングを行い、前記(9)の方法で通気抵抗を測
定した。なお、採取したサンプルは測定後全断
面において連続気泡率が90%以上で、かつ空洞
率が5%未満であることを確認した。
(尺度)
10cmHg未満 ◎
10cmHg以上20cmHg未満 ○
20cmHg以上 ×
〔この値は小さい方が通気性が良く、緩衝材と
して用いた場合に衝撃値の小さな材料が得られ
る。〕
(D) 密度分布:発泡体中央部において厚み方向に
10等分し(サンプル形状:約7mm厚×30mm幅×
30mm長さ)各々について密度を測定し最大値と
最小値との差を評価した。
(尺度)
3Kg/m3未満 ◎
3Kg/m3以上6Kg/m3未満 ○
6Kg/m3以上 ×
〔この値は小さい方が、圧縮強度のバラツキの
小さな発泡体が得られる。〕
(E) 寸法変化:発泡直後の発泡体中央厚み(t0)
と発泡後3日経過時の同部分厚み(t3)とを測
定し、寸法変化率〔(1−t3/t0)×100〕によ
り評価した。
(尺度)
10%未満 ◎
10%以上20%未満 ○
20%以上 ×
〔一般に発泡体の中心部は端部よりも収縮が大
きい。そのため、この値が小さい方が厚みの差
の小さい平滑な発泡体が得られ、製品効率及び
加工上有利である。〕
(F) 繰り返し圧縮強度:採取した発泡体について
圧縮試験を歪率80%の条件で連続的に5回行
い、25%歪時における初回の応力(σ0)と5回
目の応力(σ5)との変化率〔(σ5/σ0)×100〕
により評価した。
(尺度)
40%以上 ◎
20%以上40%未満 ○
20%未満 ×
〔緩衝材料のように繰り返し衝撃が加わる用途
において、この値が小さいと性能の劣化が大き
くなるために使用できない。〕
(G) 生産性:発泡体全断面における連続気泡率が
90%以上で、かつ空洞率が5%未満の部分の占
める面積割合(取り効率)により評価した。連
続気泡率及び空洞率の測定は、試料の厚み方向
及び幅方向について各々中心部分に沿つて連続
に10か所以上サンプリングして行つた。
(尺度)
80%以上 ◎
60%以上80%未満 ○
60%未満 ×
〔この値が大きい方が同体積において製品が取
れる割合が高くなり生産効率が高い。〕
(H) ブロツキング性:発泡後10分経過した後、発
泡体を1m間隔で切断し10段に積み重ねる。1
日後サンプルを引き離し、発泡体同士の密着状
態を観察する。
(尺度)
密着しない ◎
密着しているが剥がしても表面は割れない ○
密着していて剥がすと表面が割れる ×
〔この評価は発泡後の発泡体の取扱の容易さを
表しており、密着するものは積み重ねができな
いため著しく不利となる。〕
(I) 回復性:発泡体の圧縮残留歪により評価す
る。
(尺度)
20%未満 ◎
20%以上30%未満 ○
30%以上 ×
〔この評価は所望形状に打抜きカツトする場合
の回復性を表しており、この値の大きなものは
製品寸法が小さくなり効率が悪い。〕
(J) 切断性:発泡体の表面に基準線を引き、その
線に沿つてバンドソウで切断加工を行う。但
し、使用する刃はのこ刃を用いる。
(尺度)
切断面が平滑である ◎
若干凹凸がある ○
凹凸が目立つ ×
〔この評価は所望の形状に加工する場合の切断
面の平滑性を表しており、この評価が良いもの
ほど接着性、美粧性に優れる。〕
(K) 耐候性:JIS−A−1415のフエードメータに
よる方法を用いサンプルの変化を観察した。
(尺度)
40時間以上で黄変する ◎
10時間以上40時間未満で黄変する ○
5時間未満で黄変する ×
〔この値が大きいものほど耐候性に優れ、メデ
イカル分野やフアツシヨン分野のような黄変を
嫌う用途に適した材料である。〕
(L) 耐薬品性:ASTM−D−543 56Tに準じて
各薬品に対し測定した。
(尺度)
変化しない ◎
僅かに変化する ○
変化する ×
〔この評価はメデイカル分野や防錆剤等を使用
した商品の緩衝用途において必要とされる特性
である。〕
(M) 耐水性:50℃×90%RHの雰囲気に1か月放
置し、放置前後の圧縮強度の低下率を測定し
た。
(尺度)
10%未満 ◎
10%以上30%未満 ○
30%以上 ×
〔この評価は高温多湿雰囲気中での材料の信頼
性を表している。〕
(N) 緩衝性:JIS−Z−0235に従い、落下高さ60
cm、緩衝材厚み5cmの条件で測定し、静的応力
0.05Kg/cm2以下における発生減速度の最小値で
評価する。
(尺度)
35G未満 ◎
35G以上40G未満 ○
40G以上 ×
〔この値が小さい方が軽量で精密な商品におい
て加わる衝撃が小さくなり、商品の破損が少な
くなる。〕
(O) 熱接着性:サンプル形状として50mm厚×150
mm幅×150mm長に切断したもの2片使用し、150
℃の熱板に5秒間接触後互いに密着させる。10
分後接着面を引つ張り接着状態を観察する。
(尺度)
完全に接着している ◎
僅かに接着している ○
接着しない ×
〔この評価は緩衝材として使用する場合に商品
に適した形状に材料を加工する上で重要な特性
であり、熱接着が可能であると接着剤なしで容
易に加工できる。〕
(P) 熱成形性:サンプル形状として10mm厚×200
mm×200mm長のものを使用し、真空成形性を評
価する。
(尺度)
成形できる ◎
条件は狭いが成形できる ○
成形できない ×
〔この評価は発泡体の形状がシート状の場合に
通気性の優れた容器として使用する上で重要な
特性である。〕
〔実施例〕
次に実施例によつて本発明を具体的に説明す
る。
実施例 1
スクリユー先端部に混練ゾーンを有し当該混練
ゾーンに発泡剤を注入する注入ラインを付した
150mm口径押出機と押出機の出口に接続され重合
体の温度を調整する熱交換器及び熱交換器の出口
に取り付けられた6.0mm厚×120mm幅のダイからな
る押出発泡装置を使用し、ポリマーとしてポリブ
テン−1樹脂(M.I.1.0g/10分、密度0.19g/
cm3、融点112℃、過冷却度50℃)100重量に対しイ
オノマー樹脂(M.I.1.0g/10分、密度0.95g/
cm3、融点90度、過冷却度40℃)60重量部、核剤と
してタルク0.1重量部を添加したものを使用し、
発泡剤としてジクロロジフルオロメタンをポリマ
ーに対し20重量部加熱混練し、ダイより低圧域に
押出発泡させた。得られた発泡体は、密度が
0.027g/cm3で空洞がなく、気泡も均一な連続気
泡のものであつた。
比較例 1
ポリマーとしてアイソタクチツクポリプロピレ
ン樹脂(M.I.0.26g/10分、密度0.91g/cm3)100
重量部及び1,2−ポリブタジエン樹脂(M.
I.0.25g/10分、密度0.91g/cm3)20重量部、及
び重曹とクエン酸を夫々0.3重量部混合したもの
を使用し、発泡剤としてトリクロロモノフルオロ
メタンとジクロロテトラフルオロエタンを夫々
21.6重量部注入したこと以外は実施例1と同様の
方法で発泡させた。
得られた発泡体は、密度が0.023g/cm3で断面
が小さく空洞の大きなものであり、最適発泡温度
範囲の極めて狭いものであつた。
比較例 2
ポリマーとして低密度ポリエチレン樹脂(M.
I.4.5g/10分、密度0.927g/cm3)100重量部に対
しイオノマー(M.I.10g/10分、密度0.95g/
cm3)70重量部及びタルク0.6重量部を使用し、発
泡剤としてジクロロテトラルオロエタンを30重量
部注入したこと以外は実施例1と同様の方法で発
泡させた。
得られた発泡体は、密度が0.033g/cm3で断面
が小さく空洞の大きなものであつた。
比較例 3
ポリマーとして高密度ポリエチレン樹脂(M.
I.15g/10分、密度0.965g/cm3)100重量部に対
しイオノマー(M.I.2.8g/10分、密度0.95g/
cm3)120重量部、タルク0.6重量部を混合したもの
を使用し、発泡剤としてジクロロテトラフルオロ
エタンを30重量部注入したこと以外は実施例1と
同様の方法で発泡させた。
得られた発泡体は、密度が0.033g/cm3で断面
が小さく空洞の大きなものであつた。
比較例 4
ポリマーとしてエチレン−酢酸ビニル共重合体
(M.I.1.4g/10分、密度0.93g/cm3)100重量部に
対しイオノマー(M.I.2.8g/10分、密度0.95g/
cm3)70重量部、タルク0.6重量部を混合したもの
を使用し、発泡剤としてジクロロテトラフルオロ
エタンを30重量部注入したこと以外は実施例1と
同様の方法で発泡させた。
得られた発泡体は、密度が0.035g/cm3で空洞
の非常に大きなものであつた。
比較例 5
ポリマーとしてエチレン85重量%、アクリル酸
5重量%及び三級ブチルアクリレート10重量%か
らなるM.I.4g/10分のものを使用し、スクリユ
ー押出機内でタルク3重量部、粒径100μ以下の
乾燥酸化亜鉛3重量部とイソブタン15重量部とを
175℃で混合する以外は実施例1と同様の方法で
発泡させた。発泡温度を110℃とし、ダイ先端部
を塞いだ状態で内部で発泡しない程度の圧力に保
ち、1.5時間滞留させた後再押出し発泡させた。
得られた発泡体は、密度が0.065g/cm3で断面
が小さく、気泡が不均一であり、収縮の大きなも
のであつた。
比較例 6
ポリマーとしてイオノマー(M.I.1.0g/10分、
密度0.95g/cm3)単体を使用し、発泡剤としてジ
クロロテトラフルオロメタンをイオノマーに対し
25重量部注入したこと以外は実施例1と同様の方
法で発泡させた。
得られた発泡体は、密度が0.054g/cm3で断面
が小さく、通気性に乏しく、収縮の大きなもので
あつた。
比較例 7
ポリマーとしてポリブテン−1樹脂(M.I.1.0
g/10分、密度0.91g/cm3)単体を使用すること
以外は実施例1と同様の方法で発泡させた。
得られた発泡体は、密度が0.025g/cm3で空洞
が大きく、生産性の低いものであつた。
第1表に実施例1及び比較例1〜7により得ら
れる発泡体において、前記評価方法に従い、断面
倍率、空洞性、通気性、密度分布、寸法変化、繰
り返し圧縮強度、生産性についての評価結果を示
す。
この表から分かるように、本発明により得られ
る発泡体はすべての評価において満足できるもの
であつた。
実施例2〜5及び比較例8、9
実施例1で使用したポリブテン−1樹脂とイオ
ノマーの比率を第2表で示した比率に変更しただ
けで、その他は実施例1と同じ方法で発泡させ
た。
第2表から分かるように、イオノマーの量が10
重量部より少ないと空洞の発生が顕著となり、
100重量部を超えると通気性及び寸法変化が悪化
する。
実施例6〜8及び比較例10、11
発泡体を構成するポリブテン−1樹脂の過冷却
度を10〜90℃の間で変化させた以外は実施例1と
同じ方法で発泡させた。
得られた発泡体は、概ね同様の特性のものであ
つたが、ブロツキング性、回復性、切断性におい
て若干の差があつた。
第3表に得られた発泡体における特性差を示
す。この表から分かるように、発泡体を構成する
ホリブテン−1の過冷却度が20℃より低いと回復
性が悪くなり、70℃より高いとブロツキング性及
び切断性に問題が出るため、ポリブテン−1の過
冷却度は20〜70℃の範囲にあることが望ましい。
実施例9及び比較例12、13
本発明で得られる発泡体と、従来からある連続
気泡体である軟質ウレタンフオーム及びポリビニ
ルアルコールフオームについて前記評価方法に従
い、耐候性、耐薬品性、耐水性、緩衝性、熱接着
性、熱成形性の比較を行つた。
第4表に比較結果を示す。この表から分かるよ
うに、本発明品はすべての評価において満足でき
る水準のものであつた。
[Industrial Field of Application] The present invention relates to an improved technology for an open-cell foam made of polyolefin resin and a method for producing the same. The present invention relates to an open-cell polyolefin resin foam that can be effectively and beneficially exhibited, and a method for producing the same. [Prior Art] Soft urethane foam has been well known as a synthetic resin open-cell foam (also referred to as open-cell foam). This material is flexible, has good processability, and can be supplied at a relatively low cost, so it can be used as a cleaning material, a filter material, a sound absorbing material, a water absorbing material, a cushioning material, etc.
It is used in large quantities in a wide range of fields such as cushioning and protection materials. In particular, in the field of cushioning materials for packaged objects with low permissible impact resistance, such as computer floppy disk devices, so-called "altitude" materials that can achieve a low maximum deceleration (low G value) in the region of low static stress are used. The marketability of urethane foam as a ``cushioning material with a cushioning performance of '' has become monopolistic. On the other hand, attempts to utilize polyolefin resins in the field of open-cell foams have also been made for some time. If the excellent properties of the polyolefin resin itself, such as chemical resistance such as acid resistance and alkali resistance, and durability and robustness such as heat resistance, water resistance, and weather resistance, are imparted to the open-cell foam, these This is because it will be possible to replace soft urethane foam, which lacks durability and robustness, and it is thought that a major market for polyolefin resin foam will be created there. However, the current situation is that this is unlikely to happen. The reason for this is said to be the following. [Problems to be Solved by the Invention] That is, polyolefin resins generally have poor compatibility with volatile foam materials and also have poor retention as a gas body. Moreover, the flow viscoelasticity during melting has the property of rapidly changing near the suitable foaming temperature. Therefore, when using this product for extrusion foaming, the foaming agent should be dispersed in a larger amount in the resin and maintained at a pressure that does not cause foaming, and the pressure and heating conditions in the extruder should be adjusted. Immediately after extrusion, the flow orientation of the resin occurs, which tends to cause multi-dimensional foam expansion, which cannot be balanced with the extrusion conditions, resulting in a foam with a small cross-sectional area that is significantly below the extruder equipment capacity. During foaming, the foaming agent volatilizes and evaporates rapidly, so that foaming (low density) does not proceed, and the result is a foam with significant shrinkage and deformation, or the formation of open cells at a temperature higher than the temperature for forming closed cells. In the temperature range, the viscoelasticity of the resin rapidly decreases, resulting in the simultaneous occurrence of bubble communication, cell destruction, and cavitation (formation of blowholes) inside the foam. This is because there are essentially causes that result in a foam that is non-uniform and has poor cushioning performance. From the perspective of changing the base resin as a means of improving these, proposals have been made to use a single ethylene ionomer resin (Japanese Patent Publication No. 58-41297), and to use a mixture of polypropylene resin and 1,2-polybutadiene resin. (Japanese Unexamined Patent Publication No. 56-60233), a proposal to use resins in which ethylene-based ionomer resins are mixed with polyolefin resins such as low-density polyethylene, high-density polyethylene, and ethylene-vinyl acetate copolymers (Japanese Unexamined Patent Publication No. 59-1982). 194820 (Japanese Patent Laid-Open No. 1948-48145), and a proposal for foaming an ethylene ionomer resin by sufficiently dissolving a foaming agent therein while metal-crosslinking the resin in an extruder (Japanese Patent Application Laid-Open No. 46-48145). These proposals have generally been improved to the extent that a foam with a cross-sectional area of about 200 cm 2 can be obtained, but obtaining a foam with a cross-sectional area of about 200 cm 2 requires the hollowness (degree of blowholes) and repeated compression. When comprehensively evaluating strength, air permeability (characteristics related to cushioning properties), density distribution, dimensional changes, and productivity of the foam itself (extruded foam), it is still difficult to find a foam that is economical and has a quality level that meets market requirements. The problem is that it is far from a satisfactory level from the viewpoint of economically increasing the cross-sectional area of the foam (see the results in Table 1). In other words, the technical level of open-cell foam made of polyolefin resin is still at the level shown in Table 1, so in the field of packaging that requires ``a cushioning material with a high degree of cushioning performance'', flexible urethane foam is suitable. Despite having these shortcomings, this is the reason why it maintains its monopolistic position. From this point of view, the object of the present invention is to provide a cushioning performance similar to that of a so-called flexible open-cell urethane foam that is free of blowholes, has excellent air permeability, uniform density distribution, and repeated compressive strength, and has little dimensional change. A state that satisfies economic efficiency as an open-cell foam made of polyolefin resin that has weather resistance, chemical resistance, water resistance, thermal adhesiveness, and thermoformability (a state in which a large cross-sectional area can be secured with good productivity) ). [Means for Solving the Problems] The main structural parts common to both the first invention (foam) and the second invention (manufacturing method) of the present invention are: (a) The base resin used is polybutene. -1 resin [A] is a mixed resin of 100 parts by weight and ethylene ionomer resin [B] 10 to 100 parts by weight, and the polybutene-1 resin [A] has a degree of supercooling of 20 to 70°C as measured by DSC. (b) The target foam is an open-cell foam having a homogeneous cell structure with a cross-sectional area of 150 cm 2 or more, and is a combination of (a) and (b). The present invention will be described in detail below using tables and drawings. First, a method for producing a foam will be explained in order to deepen the understanding of the invention. Table 1 (corresponding to Example 1 and Comparative Examples 1 to 7) is
This is an attempt to concretely explain the content of the present invention in comparison with that of the prior art regarding the selection of the base resin type of the present invention. That is, evaluation items b to g in Table 1 have a cross-sectional area of 300 cm 2 and a target density of 30 kg/
Cavity (occurrence of blowholes ), air permeability, density distribution, dimensional changes,
The quality of the resulting foam, such as repeated compression strength, and the productivity of the foam were evaluated. Also, Table 1, item a, evaluates the possibility of increasing the cross-sectional area of the foam. According to the results in sections a to g of this Table 1,
A method for producing a foam that can achieve the object of the present invention is as follows:
As the base resin used for foaming, a mixed resin of polybutene-1 resin [A] and ethylene ionomer resin [B], which is unique to the present invention, is used. If resin [A] is replaced with, for example, polypropylene resin, low/high density polyethylene, or ethylene-vinyl acetate copolymer, for example, cavities (occurrence of blowholes) will be significant, and on the other hand, air permeability will deteriorate, resulting in poor cushioning performance. Good foam cannot be obtained. In addition, when [A] resin is used alone, the cross-sectional magnification can be increased, and when [B] resin is used alone, it has the advantage of suppressing cavities, but both [A] and [B] have low air permeability. However, it is not possible to obtain satisfactory results in terms of productivity (see Comparative Examples 6 and 7). In these relationships, the improvement effect on the manufacturing process of the present invention achieved by mixing resins [A] and [B] is a phenomenon that was first investigated by the present inventors, and is a phenomenon that was discovered for the first time by the present inventors. This phenomenon is presumed to be due to the fact that the fluid viscoelastic properties are modified to be suitable for. That is, in the method for producing open cells by extrusion foaming of polyolefin resin, the foaming temperature conditions are set to about 2 to 6° C. higher than the foaming temperature conditions for closed cells. At this time, the viscosity of the resin in the fluid state is adjusted so that the bubbles merge with each other, reduce the number of bubbles, and do not form large bubbles. Although it is necessary to maintain a high ratio, the mixed resin consisting of [A] + [B] has a small temperature dependence of resin viscosity change in the above foaming suitable temperature range, and therefore the adjustment temperature range is expanded. It is presumed that this makes it easier to maintain the above state. Furthermore, the present invention has a great advantage in that this fluid viscoelastic state can be maintained as a non-crosslinked resin that is stable and easy to extrude. Table 2 (corresponding to Examples 2 to 5 and Comparative Examples 8 and 9)
This is a table showing the effects of the component ratios of the mixed resins [A] and [B] in the present invention. According to the results in Table 2, the effectiveness of mixing resin [B] requires at least 10 parts by weight or more per 100 parts by weight of resin [A], but 100 parts by weight is at the upper limit of the mixing effectiveness. You can clearly see the state you've reached. The mutual improvement effect obtained by mixing the [A] resin and the [B] resin of the present invention is adjusted so that the amount of the [B] resin is in the range of 30 to 60 parts by weight per 100 parts by weight of the [A] resin. It can be said that it is desirable to do so. Table 3 (corresponding to Examples 6 to 8 and Comparative Examples 10 and 11)
Another aspect of the productivity of the foam manufacturing method is that when a large number of produced foam boards are stacked and stored, the overlapping surfaces of the foam boards stick together (blocking), and the individual foam boards become unusable. Countermeasures against problems that make it difficult to handle (blocking resistance): When the finished foam board is cut and machined into a predetermined shape and size, the processed surface becomes uneven (or roughened), reducing the product value. Measures against storage (machining roughness resistance)
Alternatively, the suitability of the foam for post-processing is evaluated based on the totality of three aspects: the recovery performance of the foam against compression when punched with a mold blade of a predetermined shape and size. This side surface shows the polybutene-1 constituting the foam.
It can be adjusted by selecting the degree of "supercooling" of the resin, but according to the results in Table 3, the "degree of supercooling"
It has been shown that it is desirable to select a temperature in the range of 10 to 90°C, and more preferably in the range of 20 to 70°C. Next, the open-cell foam of the present invention will be described. The foam of the present invention is obtained by the above-described manufacturing method, and the base resin is a mixed resin of [A] + [B], [A] 100 parts by weight: [B] 100 to 10 parts by weight. The degree of supercooling measured by DSC of resin [A] is
It is a foam with an open cell structure at a temperature of 20 to 70°C. Figures 1 and 2 are structural photographs of the cell membrane showing the shape of the holes formed in the bubble membrane (taken with an electron microscope at 20x magnification).
FIG. 1 shows a product according to the present invention, and FIG. 2 shows a comparative product [B] made of resin alone. The feature of the present invention shown in FIG. 1 is that the shape distribution of the holes drilled in the bubble membrane is scattered with relatively simple shapes in the comparative product.
The product of the present invention has a shape structure in which a large number of small holes are bored so that the remaining bubble film becomes mesh-like, and the openings of the holes are enlarged. The reason for this difference is that in terms of air permeability, the product of the present invention (Fig. 1) is better (low air resistance), while the comparative product (Fig. 2) is poor (high air resistance). When trying to make a soft synthetic resin foam exhibit a high degree of cushioning performance, a major factor that hinders this is the presence of gas that is closed and sealed within the foam. This is because this applies a repulsive force proportional to the amount of pressure deformation to the packaged item as an impact. The good air permeability (low ventilation resistance) evaluated in the present invention indicates the ability to quickly discharge gas within the foam commensurate with the amount of deformation when pressure deformation force is applied to the foam. . Therefore, if you add to this the repeated recovery power that shows the toughness and elasticity of the bubble membrane, it should become a high-quality cushioning material. In the foam of the present invention (Fig. 1), the cell membrane wall left in a network provides the above-mentioned repeated recovery force, and the holes with large opening areas provide breathability, making it an ideal buffer. I can demonstrate my abilities. FIG. 3 is a comparison diagram of the cushioning performance with a commercially available product, where A shows the foam of the present invention (Example 1), B shows the soft urethane foam, and C shows the polyvinyl alcohol foam. In the figure, the horizontal axis is static stress (Kg/cm 2 ),
The vertical axis represents the maximum deceleration (G). According to the results shown in Figure 3, the foam of the present invention exhibits a low G-value cushioning performance with a maximum deceleration of approximately 32G at a low static stress of approximately 0.02 to 0.03Kg/ cm2 . ing. This buffering performance is comparable to that of soft urethane foam. Table 4 (corresponding to Example 9 and Comparative Examples 12 and 13) is
In addition to the cushioning properties, the foams A, B, and C were also evaluated for weather resistance, chemical resistance, water resistance, heat resistance, and thermoformability, and are compared from a comprehensive viewpoint. According to the results in Table 4, the foam of the present invention has excellent foaming properties that are superior to flexible urethane foam in all of weather resistance, chemical resistance, water resistance, thermal adhesion, and thermoformability. It can be said that it is the body. In particular, it has weather resistance and water resistance, which makes it useful outdoors, chemical resistance, which makes it useful for industrial and pharmaceutical materials, and thermal adhesiveness and thermoformability. This point can be noted as something that increases the usefulness of making it easier to use, such as processing to enlarge the area and thicken it by splicing and overlapping, and shaping processing to add to the shape. Specifically, for example, a filter,
Sound absorbing materials, water absorbing materials, oil absorbing materials, humidity sensors, diaper covers, joint materials, feminine hygiene products and shoes,
It is used as a cushioning material for socks, daily necessities, and various cases. In particular, it has low compressive strength and excellent cushioning performance, making it an extremely suitable cushioning material for protecting light and fragile products such as silicon wafers and floppy disk devices. As the blowing agent used in the present invention, ordinary volatile blowing agents are used. Typical examples include lower hydrocarbons such as propane, butane, pentane, pentyne, and hexane, methylene chloride, methyl chloride, trichloromonofluoromethane, dichloromonofluoromethane, monochlorodifluoromethane, monochlorotrifluoromethane, dichlorodifluoromethane, 1, 1-difluoroethane, 1
-Chloro-1,1-difluoroethane, 1,2-
There are halogenated hydrocarbons such as dichlorotetrafluoroethane and monochloropentafluoroethane. Mixtures of these are also useful. The amount of the blowing agent is usually 5 to 50 parts by weight per 100 parts by weight of the mixed resin of polybutene-1 and ionomer. For producing the open-cell foam of the present invention, equipment similar to known extrusion foaming equipment can be used. this is,
Examples include a method in which a foaming agent is mixed with the resin composition or injected into the middle of an extruder, kneaded and melted under high temperature and high pressure, and then continuously extruded into a low pressure zone. Further, a small amount of a metal soap such as zinc stearate, or an inorganic fine powder such as calcium silicate, talc, or calcium carbonate may be contained as a lubricant or a bubble regulator. Further, depending on the case, it is also possible to add an ultraviolet deterioration inhibitor, an oxidation stabilizer, a coloring agent, etc. Furthermore, for the purpose of improving the physical properties of the foam, a thermoplastic synthetic resin that does not interfere with the formation of open cells can be added. Next, a method for measuring characteristics used in the present invention will be described. (1) Degree of supercooling of polymer The peak temperature (melting point = Tm℃) when melting at 10℃/min using DSC (PerkinElmer Model IB) and the tangential line when cooling at 10℃/min (supercooling degree = Tm)
−Tc). (2) Degree of supercooling of polybutene-1 resin constituting the foam The melting point and crystallization onset temperature of the foam formed into a sheet by hot pressing are measured by the method described in (1). As shown in FIG. 4, the difference between the higher melting point (T 2 ) and the higher crystallization initiation temperature (T 3 ) is defined as the degree of supercooling of the polybutene-1 resin constituting the foam. (3) Polymer MI ASTM-D-1238-70, Condition D (measurement temperature
(190℃, load 2.16Kg). (4) Polymer density Determined according to ASTM-D-1505. (5) Open-cell ratio of foam It was determined according to ASTM-D-2856 using an air pycnometer (model 930) manufactured by Toshiba Beckman. (6) Cross-sectional area of foam A stably produced sample is cut at 5 points every 1 m, ink is applied to the cut surfaces, and the cut surfaces are copied onto white paper. Measure the cross-sectional area of the copied object using a planimeter. The average value of the five points is taken as the cross-sectional area of the foam. (7) Cavity area of foam Copy a cross section using the same method as in (6), measure the area of any cavity with an area of 25 mm 2 or more, and add up the cavity area for each cross section. Adopt the average value of 5 locations. (8) Cell diameter of foam: 30 by the method described in ISO NG/10N 159
Calculated from the number of bubbles crossing a straight line in mm. (9) Airflow resistance of foam A sample of 50 mm thickness x 150 mm width x 150 mm length was placed on a chamber with an opening of 140 mm x 140 mm according to the method described in ASTM-D-1564, and a flow rate of 150 mm was placed on a chamber with an opening of 140 mm x 140 mm. Measure the pressure inside the chamber when suctioning at min. (10) Foam density Measured according to the method described in JIS-K-6767. (11) Foam compression test Measure according to the method described in JIS-K-6767. (12) Compression residual strain of foam In the above compression test, the strain is measured at the time when the foam no longer exhibits stress after unloading after 80% compression. The evaluation method and evaluation scale used in the present invention will be described below. In addition, (B) to (G) in the following items are evaluations of foams with a cross-sectional area of approximately 300 cm 2 (approximately 70 mm thickness x 400 mm width) and an average density of 30 Kg/m 3. It is. (A) Cross-sectional magnification: The average cell diameter of the foam to be collected.
Evaluated by the cross-sectional magnification when foaming was performed at a shear rate that was adjusted to 1.0 mm and the extrusion rate was reduced to the limit that does not cause foaming in the die [Cross-sectional magnification = (cross-sectional area of foam ÷ die opening area) x 100] . (Scale) 40 or more ◎ More than 30 but less than 40 ○ Less than 30 × [The larger this value is, the larger the product can be made with a larger cross-section even with a small extruder, which is advantageous in terms of work efficiency and energy. ] (B) Cavity: Evaluated by the cavity ratio, which is the area ratio of the cavity to the cross-sectional area of the foam.
(Cavity area ÷ cross-sectional area) x 100]. (Scale) Less than 5% ◎ 5% or more and less than 10% ○ 10% or more (C) Air permeability: Sampling was performed at the center of the foam, and the air permeability resistance was measured using the method described in (9) above. After measurement, it was confirmed that the sample had an open cell ratio of 90% or more and a void ratio of less than 5% in all cross sections. (Scale) Less than 10cmHg ◎ 10cmHg or more and less than 20cmHg ○ 20cmHg or more ] (D) Density distribution: in the thickness direction at the center of the foam
Divide into 10 equal parts (sample shape: approx. 7mm thick x 30mm wide x
30 mm length), the density was measured for each, and the difference between the maximum and minimum values was evaluated. (Scale) Less than 3Kg/m 3 ◎ 3Kg/m 3 or more and less than 6Kg/m 3 ○ 6Kg/m 3 or more × [The smaller this value is, the smaller the variation in compressive strength can be obtained. ] (E) Dimensional change: center thickness of foam immediately after foaming (t 0 )
and the thickness (t 3 ) of the same portion 3 days after foaming were measured and evaluated based on the dimensional change rate [(1-t 3 /t 0 )×100]. (Scale) Less than 10% ◎ 10% or more and less than 20% ○ 20% or more × [Generally, the center of the foam shrinks more than the edges. Therefore, the smaller this value is, the smoother the foam with a smaller difference in thickness can be obtained, which is advantageous in terms of product efficiency and processing. ] (F) Repeated compressive strength: Compression tests were performed on the sampled foams five times consecutively at a strain rate of 80%, and the stress at the first time (σ 0 ) at 25% strain and the stress at the fifth time (σ 5 ) [(σ 5 /σ 0 )×100]
Evaluated by. (Scale) 40% or more ◎ 20% or more and less than 40% ○ Less than 20% × [In applications where shocks are applied repeatedly, such as cushioning materials, if this value is small, the performance will deteriorate significantly, so it cannot be used. ] (G) Productivity: The percentage of open cells in the entire cross section of the foam is
Evaluation was made based on the area ratio (removal efficiency) occupied by a portion with a void ratio of 90% or more and less than 5%. The open cell ratio and void ratio were measured by consecutively sampling 10 or more locations along the center of each sample in the thickness direction and width direction. (Scale) 80% or more ◎ 60% or more and less than 80% ○ Less than 60% × [The larger this value is, the higher the proportion of product that can be obtained from the same volume, and the higher the production efficiency. (H) Blocking property: After 10 minutes after foaming, cut the foam into 1m intervals and stack them in 10 tiers. 1
After a day, the sample was separated and the state of adhesion between the foams was observed. (Scale) Not adhering ◎ Adhering but the surface will not break even if removed ○ Adhering but the surface will crack if removed Things are at a significant disadvantage because they cannot be stacked. ] (I) Recovery property: Evaluated by compressive residual strain of the foam. (Scale) Less than 20% ◎ 20% or more and less than 30% ○ 30% or more bad. ] (J) Cutability: Draw a reference line on the surface of the foam and cut along the line with a band saw. However, the blade used is a saw blade. (Scale) The cut surface is smooth. ◎ Some unevenness. ○ The unevenness is noticeable. Excellent cosmetic properties. (K) Weather resistance: Changes in the sample were observed using a method using a fade meter according to JIS-A-1415. (Scale) Yellowing in 40 hours or more ◎ Yellowing in 10 hours or more but less than 40 hours ○ Yellowing in less than 5 hours This material is suitable for applications where yellowing is a concern. ] (L) Chemical resistance: Measured for each chemical according to ASTM-D-543 56T. (Scale) No change ◎ Slight change ○ Change × [This evaluation is a characteristic required in the medical field and in cushioning applications for products that use rust preventives. ] (M) Water resistance: It was left in an atmosphere of 50°C x 90% RH for one month, and the rate of decrease in compressive strength before and after being left was measured. (Scale) Less than 10% ◎ 10% or more and less than 30% ○ 30% or more × [This evaluation represents the reliability of the material in a high temperature and humid atmosphere. ] (N) Cushioning property: Drop height 60 according to JIS-Z-0235
Static stress
Evaluate based on the minimum value of deceleration occurring at 0.05Kg/cm2 or less . (Scale) Less than 35G ◎ More than 35G and less than 40G ○ More than 40G ] (O) Thermal adhesiveness: Sample shape: 50mm thick x 150
Use 2 pieces cut into mm width x 150 mm length, 150
After contacting a hot plate at ℃ for 5 seconds, they are brought into close contact with each other. Ten
After a minute, pull the adhesive surface and observe the adhesion state. (Scale) Completely bonded ◎ Slightly bonded ○ Not bonded If adhesive is possible, it can be easily processed without adhesive. ] (P) Thermoformability: Sample shape: 10mm thick x 200
A piece with a length of mm x 200 mm is used to evaluate vacuum formability. (Scale) Can be molded ◎ Can be molded under narrow conditions ○ Cannot be molded × [This evaluation is an important characteristic when the foam is in the form of a sheet and is used as a container with excellent air permeability. ] [Example] Next, the present invention will be specifically explained with reference to Examples. Example 1 A kneading zone was provided at the tip of the screw, and an injection line was attached to inject the foaming agent into the kneading zone.
Using an extrusion foaming device consisting of a 150 mm diameter extruder, a heat exchanger connected to the outlet of the extruder to adjust the temperature of the polymer, and a 6.0 mm thick x 120 mm wide die attached to the outlet of the heat exchanger, the polymer was As polybutene-1 resin (MI 1.0g/10 min, density 0.19g/
cm 3 , melting point 112℃, supercooling degree 50℃) ionomer resin (MI 1.0g/10 min, density 0.95g/
cm 3 , melting point 90 degrees Celsius, supercooling degree 40 degrees Celsius), 60 parts by weight, with 0.1 parts by weight of talc added as a nucleating agent,
20 parts by weight of dichlorodifluoromethane as a foaming agent was heated and kneaded with the polymer, and the mixture was extruded into a low pressure region through a die and foamed. The resulting foam has a density of
There were no cavities at 0.027 g/cm 3 , and the cells were uniform and open cells. Comparative Example 1 Isotactic polypropylene resin as polymer (MI 0.26 g/10 min, density 0.91 g/cm 3 ) 100
Parts by weight and 1,2-polybutadiene resin (M.
I.0.25g/10 minutes, density 0.91g/ cm3 ) 20 parts by weight, and a mixture of 0.3 parts by weight each of baking soda and citric acid, and trichloromonofluoromethane and dichlorotetrafluoroethane as blowing agents.
Foaming was carried out in the same manner as in Example 1, except that 21.6 parts by weight was injected. The resulting foam had a density of 0.023 g/cm 3 , a small cross section and large cavities, and an extremely narrow optimum foaming temperature range. Comparative Example 2 Low density polyethylene resin (M.
I.4.5g/10min, density 0.927g/ cm3 ) to 100 parts by weight of ionomer (MI10g/10min, density 0.95g/cm3)
Foaming was carried out in the same manner as in Example 1, except that 70 parts by weight of cm 3 ) and 0.6 parts by weight of talc were used, and 30 parts by weight of dichlorotetraloroethane was injected as a foaming agent. The resulting foam had a density of 0.033 g/cm 3 , a small cross section, and large cavities. Comparative Example 3 High-density polyethylene resin (M.
I.15g/10min, density 0.965g/ cm3 ) to 100 parts by weight of ionomer (MI2.8g/10min, density 0.95g/cm3)
Foaming was carried out in the same manner as in Example 1, except that a mixture of 120 parts by weight (cm 3 ) and 0.6 parts by weight of talc was used, and 30 parts by weight of dichlorotetrafluoroethane was injected as a foaming agent. The resulting foam had a density of 0.033 g/cm 3 , a small cross section, and large cavities. Comparative Example 4 Ionomer (MI 2.8 g/10 min, density 0.95 g/cm 3 ) was added to 100 parts by weight of ethylene-vinyl acetate copolymer (MI 1.4 g/10 min, density 0.93 g/cm 3 ) as a polymer.
Foaming was carried out in the same manner as in Example 1, except that a mixture of 70 parts by weight (cm 3 ) and 0.6 parts by weight of talc was used, and 30 parts by weight of dichlorotetrafluoroethane was injected as a foaming agent. The resulting foam had a density of 0.035 g/cm 3 and had very large cavities. Comparative Example 5 A polymer containing 85% by weight of ethylene, 5% by weight of acrylic acid, and 10% by weight of tertiary butyl acrylate with an MI of 4 g/10 minutes was used, and 3 parts by weight of talc was dried in a screw extruder to a particle size of 100μ or less. 3 parts by weight of zinc oxide and 15 parts by weight of isobutane.
Foaming was carried out in the same manner as in Example 1 except that the mixture was mixed at 175°C. The foaming temperature was set to 110° C., the die tip was closed and the pressure was kept at a level that would not cause foaming inside, and after being allowed to stay for 1.5 hours, it was re-extruded and foamed. The resulting foam had a density of 0.065 g/cm 3 , a small cross section, nonuniform cells, and large shrinkage. Comparative Example 6 Ionomer (MI1.0g/10min,
Density 0.95g/cm 3 ) was used alone, and dichlorotetrafluoromethane was used as a blowing agent for the ionomer.
Foaming was carried out in the same manner as in Example 1 except that 25 parts by weight was injected. The resulting foam had a density of 0.054 g/cm 3 , a small cross section, poor air permeability, and large shrinkage. Comparative Example 7 Polybutene-1 resin (MI1.0
g/10 minutes, density 0.91 g/cm 3 ) Foaming was carried out in the same manner as in Example 1 except that a single product was used. The resulting foam had a density of 0.025 g/cm 3 , large cavities, and low productivity. Table 1 shows the evaluation results for the cross-sectional magnification, hollowness, air permeability, density distribution, dimensional change, repeated compressive strength, and productivity for the foams obtained in Example 1 and Comparative Examples 1 to 7 according to the evaluation method described above. shows. As can be seen from this table, the foam obtained by the present invention was satisfactory in all evaluations. Examples 2 to 5 and Comparative Examples 8 and 9 Foaming was performed in the same manner as in Example 1, except that the ratio of polybutene-1 resin and ionomer used in Example 1 was changed to the ratio shown in Table 2. Ta. As can be seen from Table 2, the amount of ionomer is 10
If it is less than the weight part, the formation of cavities will be noticeable,
If it exceeds 100 parts by weight, air permeability and dimensional changes will deteriorate. Examples 6 to 8 and Comparative Examples 10 and 11 Foaming was performed in the same manner as in Example 1, except that the degree of supercooling of the polybutene-1 resin constituting the foam was varied between 10 and 90°C. The resulting foams had generally similar properties, but there were slight differences in blocking properties, recovery properties, and cuttability. Table 3 shows the differences in properties of the obtained foams. As can be seen from this table, if the degree of supercooling of polybutene-1 constituting the foam is lower than 20°C, the recovery performance will be poor, and if it is higher than 70°C, problems will arise in blocking and cutting properties. The degree of supercooling is preferably in the range of 20 to 70°C. Example 9 and Comparative Examples 12 and 13 The foam obtained by the present invention and conventional open-celled soft urethane foam and polyvinyl alcohol foam were evaluated for weather resistance, chemical resistance, water resistance, and buffering according to the evaluation method described above. Comparisons were made in terms of properties, thermal adhesion, and thermoformability. Table 4 shows the comparison results. As can be seen from this table, the products of the present invention were of a satisfactory level in all evaluations.
【表】【table】
【表】【table】
【表】【table】
本発明は上述の構成を持つことにより、ブロー
ホール(空洞)の発生のない、通気性、密度分布
の均一性、繰り返しの圧縮強度に優れ、寸法変化
が小さく、かつ軟質ウレタンフオームに匹敵する
緩衝性能を有し、しかも耐候性、耐薬品性、耐水
性、熱接着性等に優れたポリオレフイン系樹脂発
泡体として、経済的(大断面積のものが十分な取
代をもつて二次加工し易い状態)に供給できると
云う効果を発揮する。
この効果は、産業界で求められていて未だ達成
されることのなかつた有益なものであるので、本
発明は産業界に果たす役割の高い優れた発明であ
る。
By having the above-mentioned structure, the present invention has excellent air permeability, uniformity of density distribution, and repeated compressive strength without the occurrence of blowholes (cavities), has small dimensional changes, and has a cushioning property comparable to that of soft urethane foam. It is economical as a polyolefin resin foam that has high performance and excellent weather resistance, chemical resistance, water resistance, thermal adhesiveness, etc. It exhibits the effect of being able to supply it to the customers (conditions). This effect is a beneficial effect that has been desired in industry but has not yet been achieved, and therefore the present invention is an excellent invention that will play a large role in industry.
第1,2図は発泡体の発泡膜に形成された穴の
状態を示すセル膜構造の電子顕微鏡写真図、第3
図は発泡体の緩衝性能の比較図である。第4図は
発泡体の過冷却度の測定の説明図である。
Figures 1 and 2 are electron micrographs of the cell membrane structure showing the state of holes formed in the foam membrane of the foam;
The figure is a comparison diagram of the cushioning performance of foams. FIG. 4 is an explanatory diagram of measurement of the degree of supercooling of a foam.
Claims (1)
レン系イオノマー樹脂〔B〕10〜100重量部の混
合樹脂からなる連続気泡発泡体で、ポリブテン−
1樹脂〔A〕がD.S.C.(示差走査熱量測定)で測
つた過冷却度が20〜70℃の範囲のものであり、発
泡体が断面積150cm2以上の均質な気泡構造を有す
る連続気泡発泡体であることを特徴とするポリオ
レフイン系樹脂の連続気泡発泡体。 2 D.S.C.(示差走査熱量測定)で測つた過冷却
度が20〜70℃の範囲のポリブデン−1樹脂〔A〕
100重量部とエチレン系イオノマー樹脂〔B〕10
〜100重量部の混合樹脂に揮発性発泡剤を高温高
圧雰囲気下で混練混合し、得られる混合物を該混
練雰囲気よりも低温低圧の雰囲気下に押出して断
面積が150cm2以上の均質な気泡構造を有する連続
気泡発泡体を得ることを特徴とするポリオレフイ
ン系樹脂の連続気泡発泡体の製造方法。[Scope of Claims] 1. An open cell foam consisting of a mixed resin of 100 parts by weight of polybutene-1 resin [A] and 10 to 100 parts by weight of ethylene ionomer resin [B].
1. An open-cell foam in which the resin [A] has a degree of supercooling measured by DSC (differential scanning calorimetry) in the range of 20 to 70°C, and the foam has a homogeneous cell structure with a cross-sectional area of 150 cm 2 or more. An open-cell foam made of polyolefin resin. 2 Polybdenum-1 resin with a degree of supercooling measured by DSC (differential scanning calorimetry) in the range of 20 to 70°C [A]
100 parts by weight and ethylene ionomer resin [B] 10
~100 parts by weight of mixed resin is kneaded with a volatile blowing agent under a high temperature and high pressure atmosphere, and the resulting mixture is extruded into an atmosphere at a lower temperature and lower pressure than the kneading atmosphere to form a homogeneous cell structure with a cross-sectional area of 150 cm 2 or more. 1. A method for producing an open-cell foam of polyolefin resin, the method comprising obtaining an open-cell foam having the following properties.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP62228182A JPS6474237A (en) | 1987-09-11 | 1987-09-11 | Open-cell foam of polyolefin resin and preparation thereof |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP62228182A JPS6474237A (en) | 1987-09-11 | 1987-09-11 | Open-cell foam of polyolefin resin and preparation thereof |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS6474237A JPS6474237A (en) | 1989-03-20 |
JPH0451574B2 true JPH0451574B2 (en) | 1992-08-19 |
Family
ID=16872495
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP62228182A Granted JPS6474237A (en) | 1987-09-11 | 1987-09-11 | Open-cell foam of polyolefin resin and preparation thereof |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS6474237A (en) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2002146080A (en) * | 2000-08-29 | 2002-05-22 | Jsp Corp | Polyolefin-based resin extruded foam and method for producing the same |
JP5757754B2 (en) * | 2011-03-07 | 2015-07-29 | 三井化学株式会社 | Oil absorber made of foam of ionomer resin |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS4974264A (en) * | 1972-11-18 | 1974-07-17 |
-
1987
- 1987-09-11 JP JP62228182A patent/JPS6474237A/en active Granted
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS4974264A (en) * | 1972-11-18 | 1974-07-17 |
Also Published As
Publication number | Publication date |
---|---|
JPS6474237A (en) | 1989-03-20 |
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