JP4540228B2 - Fiber reinforced plastic and its denture base - Google Patents

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【００２１】
表１に示すように木綿や羊毛に比し、シルク繊維はヤング率が高くて変形しにくく、衝撃剪断エネルギーが高くて丈夫であり、熱による分解点の温度も高くて耐熱性に優れる等の特徴を有し、シルク繊維は他の天然繊維に比して総合的な物性に優れている。また合成繊維は２００℃前後で分解・溶融・燃焼して有毒ガスを発生するが、シルク繊維は３００〜４００℃で燃焼して有毒ガスを発生することがなく、強度、安全性、コスト面で優れている。さらに母材に添加する場合でも透過性が高くて白濁等を起こさずに、母材の色調や色彩等に変化を起こすことが少なく、母材内部に混在しても目立たないので審美性が高い繊維強化プラスチックを製造することができる。
【００２２】
さらにシルク繊維は単に高い強度等の特性を有するだけでなく人体等の生態環境に積極的なプラス効果を有する。即ち、シルク繊維は古来から美しさ、肌触りの良さ等から重要視され有用性が認められてきたが、現代ではシルクの外套膜であるセリシンが、粘膜疾患及び皮膚疾患に有効であるなど、その薬理効果が科学的に実証され、人体に直接適用する素材としては最適な「環境素材」といえる。シルクのフィブロインも生体への適合性がよく生体材料として最適である。
【００２３】
そして、後述する実験例で母材の合成樹脂に添加するシルク繊維の形状・太さは、粉状の微砕片（原糸１ｍｍ以下のもの）、綿状の１．０デニール原糸（太さ約１０μ）、２本撚り２７デニールの撚糸（太さ約２７０μ）、４本撚り２９デニールの撚糸（太さ約２９０μ）、６本撚り３２デニールの撚糸（太さ約３２０μ）の５種類である。前記シルクの長さは、２本撚り２７デニールの撚糸、４本撚り２９デニールの撚糸、６本撚り３２デニールの撚糸はいずれも試験片の長軸方向の寸法を基本として１０ｍｍ以上の適切な長さとした。前記シルクのうち粉状の微砕片以外の形状を図３に示す。図３（ａ）は綿状１．０デニール原糸であるシルク繊維を示す部分斜視図、同図（ｂ）は２本撚り２７デニールの撚糸であるシルク繊維を示す部分斜視図、同図（ｃ）は４本撚り２９デニールの撚糸であるシルク繊維を示す部分斜視図、同図（ｄ）は６本撚り３２デニールの撚糸であるシルク繊維を示す部分斜視図である。
【００２４】
以下、母材となる合成樹脂に上記５種類のシルク繊維を各々混合添加した繊維強化プラスチック及びその義歯床について、その実施例を示す。
【００２５】
［実施例１］
繊維強化プラスチックの試験片は、合成樹脂の母材としてメタクリル酸メチル樹脂（ＰＭＭＡ）を用い、粉状微砕片、綿状１．０デニール原糸、２本撚り２７デニール撚糸、４本撚り２９デニール撚糸、６本撚り３２デニール撚糸の５種類のシルク繊維を、前記メタクリル酸メチル樹脂１８．０ｇに各々分散して添加することで製作した。試験片はＪＩＳ Ｋ７２０３（硬質プラスチックの曲げ試験）に準じた標準寸法・形状に成形している。図４は製作されたメタクリル酸メチル樹脂の試験片を示す説明図であり、ＪＩＳ Ｋ７２０３の試験片の規定寸法・形状である１１０ｍｍ×１０ｍｍ×４ｍｍの矩形に仕上げられている。
【００２６】
メタクリル酸メチル樹脂へ分散・添加するシルク繊維の混合量・混合重量比率は表２に示す通りである。尚、綿状１．０デニール原糸は嵩張るため混合量・混合重量比率を他のシルクの混合量・混合重量比率に対して１／１０にしてある。
【００２７】
【表２】

【００２８】
前記試験片の製作に当たっては、厚さ４ｍｍ、長さ１１０ｍｍ、幅２１ｍｍのアルミ板の原型を製作し、型枠となる金型の中に石膏を詰めて前記原型を埋没する。前記金型の型枠は後で二分割できるようになっており、分割線にはアルミ板（原型）の厚さの中心を位置させ上下２回に分け石膏で埋没する。また埋没する型枠の石膏には上下の石膏が分離するように予め硬化した下面の石膏には分離材（合成中性洗剤）を塗布しておく。石膏が硬化した後、上下の型枠及び石膏を分割して原型のアルミ板を取り出す。上記工程で試験片を製作する際の石膏型が完成する。完成した石膏型の内面には、試験片素材と石膏との分離材としてアルギン酸ナトリウム系分離材を塗布して十分に乾燥させておく。
【００２９】
試験片の母材となるメタクリル酸メチル樹脂は重合体粉末と単量体液体とから製作する。前記重合体粉末の組成は微粉末状ＰＭＭＡ（ポリメチルメタクリレート・重合体）９９．０〜９９．３％、過酸化ベンゾイル（重合開始剤）０．２〜０．５％、着色剤０．５％であり、前記単量体液体の組成はＭＭＡ（モノメチルメタクリレート・単量体）８４〜１００％、ＥＤＭＡ（エチレングリコールジメタクリレート・架橋剤）０〜１６％、ハイドロキノン（重合禁止剤）０．００５％である。本実施例の試験片製作には、（株）ハイデンタル・ジャパン社製のイソレジンＨを使用した。
【００３０】
前記重合体粉末１８０ｇに対して前記単量体液体７７．４ｍｌを混和すると室温２３℃で約１５分経過後に餅状の前重合段階に入る。十分な可塑性を有する前重合段階で上下に分割された石膏型に上下均等に填入し、この間に長方向に揃えた各種類のシルクを試験片の長軸方向（１１０ｍｍの方向）に対して平行に所定重量比で分散して添加する。なお微砕片のシルク繊維は予め重合体粉末に混入しておく。その後、ポリエチレンフィルムを介して石膏型を合わせて５ｋｇｆ／ｃｍ-^３の圧力で試圧し、試圧後に石膏型を分割して余剰の填入物を除去する。その後、ポリエチレンフィルムを介さずに石膏型を合わせて試圧同様の圧力で結合させ乾式重合法で加熱重合を行い、１００℃で約１５分間加熱後に徐冷して試験片材料を取り出す。重合完了後の試験片材料は規定寸法に切断し試験片が完成する。
【００３１】
そして、上記製作工程で得られた試験片に対し、ＪＩＳ Ｋ７２０３（硬質プラスチックの曲げ試験）による抗破折試験を行った。試験機器にはインストロン型万能試験機・島津ＡＧ−５０００Ａ（滋賀県工業試験所所有）を使用し、試験設定条件は、試験形態ＳＩＮＧＬＥ ＢＥＮＤ（単方向曲げ試験）、試験圧子移動速度２０．０００ｍｍ／分、試験圧子２０．０００ＫＧＦ、支点間距離８０．０００ｍｍとした。前記設定条件で抗破折試験を実施して、各シルク混合条件別に各四片の試験片を試験してデータを取得した（内一本試験不能）。また比較対象として、シルク無添加のメタクリル酸メチル樹脂とポリスルフォン樹脂の試験片からもデータを取得した。抗破折試験による最大荷重値（曲げ応力値）を各シルク混合条件別に表３〜表７に示す。表中の最大荷重値（曲げ応力値）の単位はＭＰａである。
【００３２】
【表３】

【００３３】
【表４】

【００３４】
【表５】

【００３５】
【表６】

【００３６】
【表７】

【００３８】
上記表３〜表７の試験結果をグラフに示す。図６は粉状微砕片シルクの混合重量比率と最大荷重時曲げ応力との関係を示すグラフ、図７は綿状原糸１．０デニールシルクの混合重量比率と最大荷重時曲げ応力との関係を示すグラフ、図８は２本撚り２７デニールシルクの混合重量比率と最大荷重時曲げ応力との関係を示すグラフ、図９は４本撚り２９デニールシルクの混合重量比率と最大荷重時曲げ応力との関係を示すグラフ、図１０は６本撚り３２デニールシルクの混合重量比率と最大荷重時曲げ応力との関係を示すグラフ、図１１は粉状徴砕片、２本撚り２７デニール、４本撚り２９デニール、６本撚り３２デニールの各添加シルクの混合重量比率と最大荷重時曲げ応力との関係を示すグラフである。図６〜図１１中で、１点鎖線はシルク無添加のメタクリル酸メチル樹脂の曲げ応力を、破線はポリスルフォン樹脂の曲げ応力を示している。
【００３９】
図６〜図１１の試験結果から判断すると、シルク繊維を添加したメタクリル酸メチル樹脂はシルク無添加のメタクリル酸メチル樹脂に比較して、いずれも曲げ応力が向上しており強度が高まっている。特に綿状原糸１．０デニール、２本撚り２７デニール撚糸、４本撚り２９デニール撚糸、６本撚り３２デニール撚糸の４種類を混合した場合は、図１１のシルク無添加メタクリル酸メチル樹脂（１点鎖線）より上の領域で示されるように確実且つ顕著に強度が増し、最大で５９．３％もの曲げ応力による強度向上がみられ、シルク繊維を添加した繊維強化プラスチックの有効性が確認された。更にシルク繊維が原糸・撚糸で混合重量比率が２．２％以上であるときには、いずれも強度の向上がより顕著であった。
【００４０】
添加シルク繊維の混合重量比率を０．５５％、２．２％、４．４％と増加するに従い強度が向上し、ポリスルフォン樹脂に匹敵する曲げ応力による強度が得られるようになるが、図１０に示すように６本撚り３２デニール撚糸の混合重量比率を１５％とした場合には４．４％のときより強度が低下している傾向がみられるので、メタクリル酸メチル樹脂を母材とした場合には６本撚り３２デニール撚糸で４．４％と１５％との間にシルクの最適な混合重量比率が存在すると考えられる。他の傾向として、添加シルク繊維の太さが太いほど曲げ応力による強度が向上し且つその試験データの安定性がみられ、又綿状原糸１．０デニールの場合には混合量が他の添加シルク繊維に比して１／１０であるにも関わらず顕著な曲げ応力による強度の向上が確認された。
【００４１】
［実施例２］
繊維強化プラスチックの試験片は、合成樹脂の母材にポリエチレン（ＰＥ）を用い、粉状微砕片、綿状１．０デニール原糸、２本撚り２７デニール撚糸、４本撚り２９デニール撚糸、６本撚り３２デニール撚糸の５種類のシルク繊維を、前記ポリエチレン４．０ｇに各々混合して製作した。試験片はＪＩＳ Ｋ７１１３（プラスチックの引張試験方法）の２号型試験片に準じた標準寸法・形状に成形している。図５はポリエチレンの試験片を示す説明図であり、試験片はＪＩＳ Ｋ７１１３の規定寸法・形状で全長Ａ１１５ｍｍ、両端の幅Ｂ２５±１ｍｍ、平行部分の長さＣ３３±２ｍｍ、平行部分の幅Ｄ６±０．４ｍｍ、小半径Ｅ１４±１ｍｍ、大半径Ｆ２５±２ｍｍ、標線間距離Ｇ２５±１ｍｍ、つかみ具間距離Ｈ８０±５ｍｍ、厚さＩ１〜３ｍｍに仕上げられている。
【００４２】
母材のポリエチレンヘ混合するシルク繊維の混合量・混合重量比率は表８に示す通りである。なお綿状１．０デニール原糸は嵩張るために混合量・混合重量比率を他のシルク繊維の混合重量比率に対して１／１０にしてある。
【００４３】
【表８】

【００４４】
前記試験片の製作に当たっては、予め凹面と平滑面で２分割される金型を製作しておく。又試験片の母材であるポリエチレンには、ノバテックＬＬフイルムグレードＵＦ２４０（（株）日本ポリケム製造）を使用する。前記ＵＦ２４０の特性はＭＦＲ（流れ性の度合）２．１ｇ／１０分、密度０．９２０ｇ／ｃｍ^３（ＬＤＰＥ（直鎖状低密度ポリエチレン））、融点（融解終了点）１２４℃、軟化温度１００℃、添加助剤は無添加である。
【００４５】
母材のペレット４．０ｇと、試験片の長方向の寸法・形状に揃えて所定の重量比率に調整したシルク繊維を用意し、母材のペレットの一部を金型の凹面に溶解時に均等となるように置いて１４０℃の電気炉中で溶解し、スパチュラ（へラ）で気泡の無いように圧迫する。そして、シルクを長方向に分散して添加する。シルクの添加は、図５の平行部分の長さＣ：３３ｍｍを基本として全長Ａ：１１５ｍｍの試験片全体に均等にシルクが分布するように添加する。その後、残りのペレットを被覆後に１４０℃の電気炉で再度融解し、スパチュラで溶解した母材をシルク繊維に馴染ませる。その後、金型を合わせて５ｋｇｆ／ｃｍ^３の圧力でプレスして加圧成形後に徐冷し、余剰部分の削除など規定寸法・形状への調整を行い、試験片が完成する。
【００４６】
上記製作工程で得られた試験片に対し、ＪＩＳ Ｋ７１１３（プラスチックの引張試験方法）による引張試験を行った。試験機器には万能抗張力試験機（５ｔ）ＩＮＳＴＲＯＮ５５６９（滋賀県東北部工業センター所有）を使用し、試験設定条件は、試験形態引っ張り、クロスヘッド速度２０．０００ｍｍ／分、フルスケール荷重レンジ５０ｋｇ（試験片の一部が荷重レンジを超えたために変更した荷重レンジ：５０００ｋｇ）、試験片の掴み具間距離８０ｍｍとした。前記設定条件で引張試験を実施して、各シルク混合条件別に最大荷重時の引張応力（ＭＰａ）と最大荷重時の試験片の伸び（ｍｍ）のデータ、及び比較対象としてシルク無添加のポリエチレン試験片による同様のデータを取得した。各シルク混合条件別に引張試験による最大荷重時の引張応力（ＭＰａ）のデータを表９〜表１３に、これに対応した最大荷重時の試験片の伸び（ｍｍ）のデータを表１４〜表１８に示す。
【００４７】
【表９】

【００４８】
【表１０】

【００４９】
【表１１】

【００５０】
【表１２】

【００５１】
【表１３】

【００５２】
【表１４】

【００５３】
【表１５】

【００５４】
【表１６】

【００５５】
【表１７】

【００５６】
【表１８】

【００５７】
上記表９〜表１３の最大荷重時の引張応力（ＭＰａ）に関する試験結果をグラフに示す。図１２は粉状微砕片シルクの混合重量比率と最大荷重時引張応力との関係を示すグラフ、図１３は綿状原糸１．０デニールシルクの混合重量比率と最大荷重時引張応力との関係を示すグラフ、図１４は２本撚り２７デニールシルクの混合重量比率と最大荷重時引張応力との関係を示すグラフ、図１５は４本撚り２９デニールシルクの混合重量比率と最大荷重時引張応力との関係を示すグラフ、図１６は６本撚り３２デニールシルクの混合重量比率と最大荷重時引張応力との関係を示すグラフ、図１７は粉状徴砕片、２本撚り２７デニール、４本撚り２９デニール、６本撚り３２デニールの各添加シルクの混合重量比率と最大荷重時引張応力との関係を示すグラフである。図１２〜図１７中で破線、一点鎖線、二点鎖線はシルク無添加のポリエチレン樹脂の最大荷重時引張応力を示している。
【００５８】
図１２〜図１７について検討すると、２本撚り２７デニール撚糸、４本撚り２９デニール撚糸、６本撚り３２デニール撚糸の場合、シルク繊維の添加量を順次増加するにつれて繊維強化プラスチックの引張応力に関する強度が顕著に増加し、特に６本撚り３２デニール撚糸の場合については引張応力に関する強度が極めて増加している。
【００５９】
さらに、上記表９〜表１３に示された最大荷重時の引張応力（ＭＰａ）と上記表１４〜表１８に示された最大荷重時の試験片伸び（ｍｍ）の対応関係のグラフを図１８に示す。図１８において、○は粉状微砕片シルク、◎は綿状１．０デニール原糸シルク、□は２本撚り２７デニール撚糸シルク、△は４本撚り２９デニール撚糸シルク、■は６本撚り３２デニール撚糸シルク、◇はシルク無添加のポリエチレンの試験結果をそれぞれ示している。
【００６０】
図１８について検討すると、シルク無添加ポリエチレンは最大荷重時の引張応力（ＭＰａ）が負荷されたときに試験片の伸び（変位）が約３００ｍｍ以上となっているが、シルク添加ポリエチレンの場合には最大荷重時の引張応力が負荷されたときに試験片の伸びが１０ｍｍ以下の範囲に移行している。この傾向は２本撚り２７デニール撚糸の２．２％以上、４本撚り２９デニール撚糸の２．２％以上、６本撚り３２デニール撚糸の０．５％以上からみられ、２本撚り２７デニール撚糸の４．４％以上、４本撚り２９デニール撚糸の４．４％以上、６本撚り３２デニール撚糸の２．２％以上では引張応力に関する強度が飛躍的に向上すると共に、最大荷重時の試験片伸びも１１ｍｍ以下に抑えられている。故に、シルク繊維の添加が繊維強化プラスチックの強度向上に有効であることが認められると共に、特にシルク繊維の太さや量の増加に伴って繊維強化プラスチックの強度が向上していることがわかる。
【００６１】
［実施例３］
繊維強化プラスチックの試験片は、合成樹脂の母材にポリプロピレン（ＰＰ）を用い、粉状微砕片、綿状１．０デニール原糸、２本撚り２７デニール撚糸、４本撚り２９デニール撚糸、６本撚り３２デニール撚糸の５種類のシルク繊維を、前記ポリプロピレン４．１ｇに各々混合して製作した。試験片はＪＩＳ Ｋ７２０３（プラスチックの曲げ試験方法）に準じた標準寸法・形状に作成した。図５はポリプロピレンの試験片を示す説明図であり、試験片はＪＩＳ Ｋ７２０３の規定寸法・形状で１１０ｍｍ×１０ｍｍ×４ｍｍの矩形に仕上げられている。
【００６２】
母材のポリプロピレンヘ混合するシルク繊維の混合量・混合重量比率は表１９に示す通りである。なお綿状１．０デニール原糸は嵩張るために混合量・混合重量比率を他のシルク繊維の混合重量比率に対して１／１０にしてある。
【００６３】
【表１９】

【００６４】
前記試験片の製作に当たっては、予め凹面より構成される２分割できる金型を製作しておく。試験片の母材であるポリプロピレンには、ノバテックＰＰ射出成形グレードＭＡ０３（（株）日本ポリケム製造）を使用する。前記ＭＡ０３の特性は、ＭＦＲ（流れ性の度合）２５ｇ／１０分、密度０．９１０〜０．９２０ｇ／ｃｍ^３、融点（融解終了点）１６３℃である。
【００６５】
母材のペレット４．１ｇと、試験片の長方向の寸法・形状に揃えて所定の重量比率に調整したシルクを用意し、母材のペレットを金型の凹面に溶解時に均等になるように置いて１６５℃の電気炉中で溶解し、スパチュラ（へラ）で気泡の無いように圧迫する。その後、シルクを試験片の長軸方向（１１０ｍｍの方向）に対して平行に均等になるように分散して添加し、余剰のシルクを試験片より切除し、スパチュラを用いて溶解した母材をシルク繊維に馴染ませる。その後、金型を合わせて５ｋｇｆ／ｃｍ^３の圧力でプレスして加圧成形後に徐冷し、取り出し余剰部分の削除など規定寸法・形状への調整を行って試験片が完成する。
【００６６】
上記製作工程で得られた試験片に対し、ＪＩＳ Ｋ７２０３（硬質プラスチックの曲げ試験方法）による抗破折試験を行った。試験機器にはインストロン型万能試験機ＯＲＩＥＮＴＥＣ ＲＴＣ−１３５０Ａ（滋賀県工業試験所所有）を使用し、試験設定条件は、試験形態ＳＩＮＧＬＥ ＢＥＮＤ（単方向曲げ試験）、試験圧子移動速度２０．０００ｍｍ／分、試験圧子２０．０００ＫＧＦ、支点間距離８０．０００ｍｍとした。前記設定条件で抗破折試験を実施して、各シルク混合条件別に各四片の試験片を試験してデータを取得した。なお比較対象として、シルク無添加のポリプロピレン試験片からもデータを取得した。抗破折試験による最大荷重値（曲げ応力値）を各シルク混合条件別に表２０〜表２４に示す。表中の最大荷重値（曲げ応力値）の単位はＭＰａである。
【００６７】
【表２０】

【００６８】
【表２１】

【００６９】
【表２２】

【００７０】
【表２３】

【００７１】
【表２４】

【００７２】
上記表２０〜表２４の最大荷重時の曲げ応力（ＭＰａ）に関する試験結果をグラフに示す。図１９は粉状微砕片シルクの混合重量比率と最大荷重時曲げ応力との関係を示すグラフ、図２０は綿状原糸１．０デニールシルクの混合重量比率と最大荷重時曲げ応力との関係を示すグラフ、図２１は２本撚り２７デニールシルクの混合重量比率と最大荷重時曲げ応力との関係を示すグラフ、図２２は４本撚り２９デニールシルクの混合重量比率と最大荷重時曲げ応力との関係を示すグラフ、図２３は６本撚り３２デニールシルクの混合重量比率と最大荷重時曲げ応力との関係を示すグラフ、図２４は粉状微砕片、２本撚り２７デニール、４本撚り２９デニール、６本撚り３２デニールの各添加シルクの混合重量比率と最大荷重時曲げ応力との関係を示すグラフである。図１９〜図２４中で破線、一点鎖線、二点鎖線、点線はシルク無添加のポリプロピレンの最大荷重時曲げ応力を示している。
【００７３】
図２４について検討すると、ポリプロピレンにシルク繊維を添加した本実施例においても繊維強化プラスチックの曲げ応力に関する強度の向上が認められた。特に２本撚り２７デニール撚糸４．４％と４本撚り２９デニール撚糸２．２％で強度の向上が顕著であった。ポリプロピレンを母材として使用した場合、シルク繊維添加の強度向上に関する有効性は、緩やかな二次曲線を伴った形で現れている。
【００７４】
［実施例４］
本実施例では繊維強化プラスチックの強度向上を多角的に検証するため、多角的な試験片の強度試験を行った。母材には人体や自然環境に悪影響を与えない代表的なプラスチックであるメタクリル酸メチル樹脂を使用し、これにシルク繊維を分散・添加して繊維強化プラスチックの試験片とする。前記試験片は、上記実施例と同様に繊維強化プラスチックの強度に対するシルクの混合状態の影響を考慮し、実験的にシルクの太さ、長さ、形状等を変えつつシルクの混合量（或いは重量比）を変化させて成形した。
【００７５】
具体的には母材であるメタクリル酸メチル樹脂１８．０ｇに、試験片に適合する寸法を有する５種類の形状のシルク繊維を分散・添加して試験片を製作した。添加するシルク繊維の形状は、粉状微砕片（原糸で１ｍｍ以下のもの）、綿状１．０デニール原糸、２本撚り２７デニール撚糸、４本撚り２９デニール撚糸、６本撚り３２デニール撚糸とし、母材に対して均等に混合して加圧を施した。シルク混合量（混合重量比）は表２５に示す通りである。なお比較対象として、ポリスルフォン樹脂とシルク無添加のメタクリル酸メチル樹脂との比較試験片を製作し、前記比較試験片にも同様の実験を試みた。
【００７６】
【表２５】

【００７７】
試験片の強度試験は、ＪＩＳ Ｋ７２０３（硬質プラスチックの曲げ試験方法）の工業規格に基づく抗破折試験で実施した。前記曲げ試験を実施するため、試験片は上記の如く母材にシルクを均一に分散・混合して冷却が完了したもので、これを前記曲げ試験方法に規定された標準寸法（１１０ｍｍ×１０ｍｍ×４ｍｍ）に切削加工したものとし、各シルクの混合重量比別に製作した。試験設備は、滋賀県工業試験場所有設備であるインストロン型万能試験機（島津製作所製オートグラフＡＧ−５０００Ａ）を用い、前記試験機の設定条件は、試験形態（ＴＥＳＴ ＭＯＤＥ）はＳＩＮＧＬＥＢＥＮＤ（単方向曲げ試験）、試験圧子移動速度（ＴＥＳＴ ＳＰＥＥＤ）は２０．０００ｍｍ／分、試験圧子荷重（Ｆ／Ｓ ＬＯＡＤ）は２０．０００ＫＧＦ（１９６．１３３Ｎ）とした。図２５に抗破折試験の概要図を示す。
【００７８】
前記抗破折試験を実施することにより、以下の強度に関するデータを取得した。このデータに基づいた応力−ひずみ関係等から、繊維強化プラスチックの材料特性を判断する。
（ａ）最大値（ＭＡＸ）。材料である試験片が、応力が増加しないで伸びが急激に増加しはじめる降伏点以前における、最大の荷重が負荷されたときの各値である。
（ｂ）破析値（ＢＲＥＡＫ）。試験片の応力が増加しないで伸びが急激に増加しはじめる降伏点以降における、荷重が負荷され試験片が折れ曲がったときの各値である。
（ｃ）最大限界値（ＬＯＡＤ ＫＧＦ）。試験片の応力がピークになったときの荷重値である。ここでは曲げ荷重を加えているので、試験片の曲げ強さの荷重である。尚、単位はＮ：ニュートンに換算して示した（１ｋｇｆ＝９．８０６６５Ｎ）。
（ｄ）曲げ値（ＥＬＯＮＧ ＭＭ）。圧子が移動した距離で、単位はｍｍである。
（ｅ）曲げ応力（ＳＴＲＥＳＳ ＫＧＦ／ＭＭ^２）。単位はＭＰａに換算して示した（１ＭＰａ＝９．８０６６５Ｎ）。
（ｆ）伸び値（ＳＴＲＡＩＮ％）。試験片に荷重を加わえて応力が生じたときに、試験片の材料を構成している分子と分子は移動して試験片は変形する。伸び値はこの変形量（もとの試験片の平面と変形した平面とのなす曲がり）の割合である。
【００７９】
以下には、混合添加するシルクの形状と添加量を変化させて試験片の抗破折試験を行った実験例を示す。試験片の母材はメタクリル酸メチル樹脂である。
【００８０】
（実験Ｎｏ．１）母材量１８．０ｇに粉状微砕片のシルク０．１ｇ（０．５５％）を添加した場合の試験結果を表２６に示す。
【００８１】
【表２６】

【００８２】
（実験Ｎｏ．２）母材量１８．０ｇに粉状微砕片のシルク０．４ｇ（２．２％）を添加した場合の試験結果を表２７に示す。
【００８３】
【表２７】

【００８４】
（実験Ｎｏ．３）母材量１８．０ｇに粉状微砕片のシルク０．８ｇ（４．４％）を添加した場合の試験結果を表２８に示す。
【００８５】
【表２８】

【００８６】
（実験Ｎｏ．４）母材量１８．０ｇに１．０デニール綿状原糸であるシルク０．０１ｇ（０．０５５％）を添加した場合の試験結果を表２９に示す。
【００８７】
【表２９】

【００８８】
（実験Ｎｏ．５）母材量１８．０ｇに１．０デニール綿状原糸であるシルク０．０４ｇ（０．２２％）を添加した場合の試験結果を表３０に示す。
【００８９】
【表３０】

【００９０】
（実験Ｎｏ．６）母材量１８．０ｇに１．０デニール綿状原糸であるシルク０．０８ｇ（０．４４％）を添加した場合の試験結果を表３１に示す。
【００９１】
【表３１】

【００９２】
（実験Ｎｏ．７）母材量１８．０ｇに、２７デニール（２本撚り）のシルク０．１ｇ（０．５５％）を添加した場合の試験結果を表３２に示す。
【００９３】
【表３２】

【００９４】
（実験Ｎｏ．８）母材量１８．０ｇに、２７デニール（２本撚り）のシルク０．４ｇ（２．２％）を添加した場合の試験結果を表３３に示す。
【００９５】
【表３３】

【００９６】
（実験Ｎｏ．９）母材量１８．０ｇに、２７デニール（２本撚り）のシルク０．８ｇ（４．４％）を添加した場合の試験結果を表３４に示す。
【００９７】
【表３４】

【００９８】
（実験Ｎｏ．１０）母材量１８．０ｇに、２９デニール（４本撚り）のシルク０．１ｇ（０．５５％）を添加した場合の試験結果を表３５に示す。
【００９９】
【表３５】

【０１００】
（実験Ｎｏ．１１）母材量１８．０ｇに、２９デニール（４本撚り）のシルク０．４ｇ（２．２％）を添加した場合の試験結果を表３６に示す。
【０１０１】
【表３６】

【０１０２】
（実験Ｎｏ．１２）母材量１８．０ｇに、２９デニール（４本撚り）のシルク０．８ｇ（４．４％）を添加した場合の試験結果を表３７に示す。
【０１０３】
【表３７】

【０１０４】
（実験Ｎｏ．１３）母材量１８．０ｇに、３２デニール（６本撚り）のシルク０．１ｇ（０．５５％）を添加した場合の試験結果を表３８に示す。
【０１０５】
【表３８】

【０１０６】
（実験Ｎｏ．１４）母材量１８．０ｇに、３２デニール（６本撚り）のシルク０．４ｇ（２．２％）を添加した場合の試験結果を表３９に示す。
【０１０７】
【表３９】

【０１０８】
（実験Ｎｏ．１５）母材量１８．０ｇに、３２デニール（６本撚り）のシルク０．８ｇ（４．４％）を添加した場合の試験結果を表４０に示す。
【０１０９】
【表４０】

【０１１０】
（実験Ｎｏ．１６）母材量１８．０ｇに、３２デニール（６本撚り）のシルク２．７ｇ（１５％）を添加した場合の試験結果を表４１に示す。
【０１１１】
【表４１】

【０１１２】
（実験Ｎｏ．１７）比較例として、規定寸法を有するポリスルフォン樹脂の試験片で行った試験結果を表４２に示す。
【０１１３】
【表４２】

【０１１４】
（実験Ｎｏ．１８）比較例として、規定寸法を有するメタクリル酸メチル樹脂の試験片で行った試験結果を表４３に示す。
【０１１５】
【表４３】

【０１１６】
次に、上記実験結果に基づき、混合添加したシルク形状別の表及びグラフを表４４〜表４８及び図２６〜図３０に示す。表４４〜表４８及び図２６〜図３０の試験結果のデータは、最大限界値（単位：Ｎ）、曲げ値（単位：ｍｍ）、曲げ応力（単位：ＭＰａ）、伸び値（単位：％）の各値として最大値（ＭＡＸ）を採用している。比較のため、比較試験片であるポリスルフォン樹脂とメタクリル酸メチル樹脂（シルク無添加）の試験結果についても前記表及びグラフに示した。
【０１１７】
（ｉ）添加シルクが粉状微砕片の場合における、複合プラスチックのシルク添加量に応じた分析結果を表４４及び図２６（ａ）、同図（ｂ）に示す。
【０１１８】
【表４４】

【０１１９】
（ｉｉ）添加シルクが綿状原糸１．０デニールの場合における、複合プラスチックのシルク添加量に応じた分析結果を表４５及び図２７（ａ）、同図（ｂ）に示す。
【０１２０】
【表４５】

【０１２１】
（ｉｉｉ）添加シルクが２本撚り２７デニールの場合における、複合プラスチックのシルク添加量に応じた分析結果を表４６及び図２８（ａ）、同図（ｂ）に示す。
【０１２２】
【表４６】

【０１２３】
（ｉｖ）添加シルクが４本撚り２９デニールの場合における、複合プラスチックのシルク添加量に応じた分析結果を表４７及び図２９（ａ）、同図（ｂ）に示す。
【０１２４】
【表４７】

【０１２５】
（ｖ）添加シルクが６本撚り３２デニールの場合における、複合プラスチックのシルク添加量に応じた分析結果を表４８及び図３０（ａ）、同図（ｂ）に示す。
【０１２６】
【表４８】

【０１２７】
また、上記実験結果に基づき、分散・添加したシルク繊維の混合重量比（添加量）別の表及びグラフを表４９〜表５１及び図３１〜図３３に示す。表４９〜表５１及び図３１〜図３３の試験結果のデータは、最大限界値（単位：Ｎ）、曲げ値（単位：ｍｍ）、曲げ応力（単位：ＭＰａ）、伸び値（単位：％）の各値として最大値（ＭＡＸ）を採用している。比較のため、比較試験片であるポリスルフォン樹脂とメタクリル酸メチル樹脂（シルク無添加）の試験結果についても前記表及びグラフに示した。なお便宜上、綿状原糸１．０デニールシルクの混合重量比０．０５５％、０．２２％、０．４４％はそれぞれ混合重量比０．５５％、２．２％、４．４％の表及びグラフに含めて表示し、又６本撚り３２デニールシルクの混合重量比１５％（添加量２．７ｇ）は全ての表及びグラフに表示した。
【０１２８】
（ｉ）シルク添加量が０．１ｇ（混合重量比０．５５％）の場合におけるシルク形状に応じた分析結果を表４９及び図３１（ａ）、同図（ｂ）に示す。なお１．０デニール綿状原糸の添加量は０．０１ｇ（混合重量比０．０５５％）である。
【０１２９】
【表４９】

【０１３０】
（ｉｉ）シルク添加量が０．４ｇ（混合重量比２．２％）の場合におけるシルク形状に応じた分析結果を表５０及び図３２（ａ）、同図（ｂ）に示す。なお１．０デニール綿状原糸の添加量は０．０４ｇ（混合重量比０．２２％）である。
【０１３１】
【表５０】

【０１３２】
（ｉｉｉ）シルク添加量が０．８ｇ（混合重量比４．４％）の場合におけるシルク形状に応じた分析結果を表５１及び図３３（ａ）、同図（ｂ）に示す。なお１．０デニール綿状原糸の添加量は０．０８ｇ（混合重量比０．４４％）である。
【０１３３】
【表５１】

【０１３４】
以上のシルク繊維の形状別及びシルク繊維の混合重量比（添加量）別の分析結果から、下記の結論が導かれる。
【０１３５】
まず、シルク繊維形状別の表４４〜表４８及び図２６〜図３０について検討すると、いずれのシルク繊維形状の場合においても、シルク添加メタクリル酸メチル樹脂の棒グラフの先端は、シルク無添加のメタクリル酸メチル樹脂の棒グラフの先端より常に上方に位置している。従って、シルクの添加が明らかに母材の強度向上に寄与し、繊維強化プラスチックが高い強度を有することがわかる。
【０１３６】
又、シルク無添加のメタクリル酸メチル樹脂やポリスルフォン樹脂は、シルク繊維を添加したメタクリル酸メチル樹脂と比較して、最大荷重時の最大限界値／Ｎ、曲げ応力／MＭＰａに対する曲げ値／ｍｍや伸び値／％が低い。一方、シルク繊維を添加した繊維強化プラスチックは、最大荷重時の最大限界値／Ｎ、曲げ応力／ＭＰａの増加に対して、曲げ値／ｍｍや伸び値／％も比例して増加している。このことから、シルク添加により応力ー歪み関係、換言すれば母材の機械的性質が向上し、シルク無添加の場合よりも強度が増して粘りを有する。
【０１３７】
また、上記グラフから、シルク繊維添加量の増加に対して強度も比例して増加しているといえない場合がある。表４４〜表４８から抜粋したシルク添加量に応じた強度順位をシルク繊維形状別に表５２に示す。表５２の強度順位は曲げ応力／ＭＰａのデータで判定している。
【０１３８】
【表５２】

【０１３９】
表５２において、シルク繊維混合重量比４．４％は２７、２９、３２デニール撚糸の各シルク形状において比較的高い強度を発揮したが、強度順位１位ではなかった。同様に、３２デニール撚糸でシルク混合重量比１５％は高い強度を発揮したものの、強度順位１位ではなかった。又締状原糸はシルク混合重量比０．２２％で、２９、３２デニール撚糸はシルク混合重量比２．２％で強度順位が１位になっている。実施例１（母材をメタクリル酸メチル樹脂とする場合）等の結果を考慮すると、繊維強化プラスチックの強度は母材に添加するシルク繊維形状にも依存すると判断できることから、繊維強化プラスチックに混合添加すべきシルク繊維には、強度の観点から最適な形状や前記形状に応じた最適な混合重量比の範囲等があると思料される。
【０１４０】
ここで、上記実験結果に対し理論的考察を試みる。
【０１４１】
試験結果から判断すると、母材であるメタクリル酸メチル樹脂等ヘシルク繊維を添加して母材の強度向上を図る場合、単純にシルク繊維の混合重量比に依存して強度が向上するというよりも、添加するシルク繊維の母材に対する体積比、シルク繊維の母材粒子との比率、シルク繊維自体の分子レベルでの断面積比などが影響して強度が向上するように思われる。そして、シルクは繊維の束の表面を取り巻くセリシンが母材である高分子プラスチック材料と親和性があるので、混合したシルクが架橋作用を発揮して母材の強度を向上し、或いはシルクの繊維構造の束自体による強化作用で母材の強度を向上すると考えられる。従って、高分子の状態であるメタクリル酸メチル樹脂等を鎖状にして結合するための形状などが添加するシルク繊維にとって重要になると思われ、かかる架橋作用や強化作用が相乗して働くことによって、強度が飛躍的に増加した繊維強化プラスチックになると考えられる。
【０１４２】
また、上述のように強度向上等の観点から、より望ましい添加シルク繊維の形状やその混合重量比等が存在すると考えられる。例えば、上記実施例１〜４で判断すると、添加シルク繊維の形状・太さは２本撚り２７デニール撚糸、４本撚り２９デニール撚糸、６本撚り３２デニール撚糸等が望ましく、その混合重量比も２．２％〜１５％程度が望ましい。これは、シルクのフィブロイン繊維自体が高分子と馴染みやすい構造で適度な強度を有すること、フィブロイン繊維束はねじれ合って細く不規則な断面を有しており、母材分子と交わり易く母材の強度を向上することの他、精錬でセリシンが除去された隙間には母材分子を取り込みやすくなって、より母材の強度を向上すること等の理由による。なお前記理由から、シルク繊維の精錬度を調整することで、高い強度が要求される場合には高い精錬を行ったシルク繊維を使用して強度を向上し、義歯床などセリシン等による薬理効果が期待される場合には比較的低い精錬度のシルク繊維を使用して薬理効果を発揮させる等が可能であり、本発明の繊維強化プラスチックには用途の多様性がある。
【０１４３】
次に、上記繊維強化プラスチックの義歯床としての適格性について説明する。
【０１４４】
表５３には義歯床に使用可能な代表的素材であるメタクリル酸メチル樹脂とポリスルフォンの特性を示す。
【０１４５】
【表５３】

【０１４６】
メタクリル酸メチル樹脂とポリスルフォン樹脂は上記のような長所、短所を備えているが、いずれも理想的な義歯床材料とはいえない。そこで、毒性がないメタクリル酸メチル樹脂にシルク繊維を混合添加した繊維強化プラスチックによって義歯床を製作する。前記義歯床の製造方法は、繊維強化プラスチックを使用して製造する以外は、通常の義歯床材料であるメタクリル酸メチル樹脂等によって義歯床を製造する技法とほぼ同様である。
【０１４７】
上記のように本繊維強化プラスチックを素材として製造した義歯床の特性について検討すると、（ア）前記繊維強化プラスチックによる義歯床はメタクリル酸メチル樹脂の義歯床よりも強度が高い、（イ）義歯床材料に使用する母材プラスチックの量を削減できる、（ウ）環境ホルモンやダイオキシンを発生する危険性がないので人体等に対し安全である、（エ）添加シルク繊維による保水作用やセリシンによる薬効作用など積極的な人体等への効果が期待できる、セリシンには血中のコレステロール値を良性にコントロールする能力もある、（オ）繊維強化プラスチックの製造に伴う環境面へのプラス作用がある、（カ）シルク繊維強化プラスチックやその義歯床は製造上容易且つ低コストであり、個々人に対するオーダーメイド等にも容易に対処しうる、等の特性があり、通常の義歯床には無い高い強度や人体への好影響等の有効性を有する。
【０１４８】
尚、ガラス繊維強化プラスチックや炭素繊維強化プラスチックなど他の繊維強化プラスチックを義歯床等の人体に直接使用する製品に用いる場合には、シルク繊維強化プラスチックと異なり、以下のような問題がある。例えば、ガラス繊維を混合した強化プラスチックを義歯床として使用することを想定した場合、義歯床は人体に装着されるものであるから、人体に対して大変危険且つ有害で安全基準をクリアできない。即ち、プラスチックとガラス繊維の摩耗率を比較するとプラスチックの摩耗率の方が大きいため、露出した繊維が口腔内に迷入する恐れがある。また、炭素繊維強化プラスチックを義歯床として使用することを想定した場合、義歯及び義歯床は個々人のオーダーメイドであるが、炭素繊維強化プラスチックの義歯床で前記オーダーメイドに対処するのは操作上困難であり、又実際に炭素繊維強化プラスチックで上記のように義歯床を製作すると、機械設備等に対する膨大な費用がかかる。これに対し、本発明によるシルク繊維強化プラスチック及びその義歯床等には上記のようなデメリットは全くなく、例えば義歯床からシルク繊維が露出してもむしろ人体等に対し積極的な好影響を与え、又容易な操作性を有するものである。
【０１４９】
本発明による繊維強化プラスチック及びその義歯床は上記構成であるから、高い強度など良好な特性を発揮すると共に、人体や自然など生態環境に対する高度な順応性を有し、地球環境の保全及び人体の健康維持を図ることができるという効果がある。即ち、前記繊維強化プラスチック及びその義歯床は、廃棄焼却時に発生するダイオキシンや環境ホルモン（内分泌攪乱化学物質）など、生態環境に対して有害な化学物質を生ずる危険性がなく、且つ強度等の特性で高機能を発揮することができる。
【０１５０】
また、上記繊維強化プラスチック及びその義歯床は合成樹脂から成形されるものであるから、加工が容易で高度な操作性及び利便性を有すると共に、製造コストが安価で経済性に優れているという効果がある。
【０１５１】
さらに上記繊維強化プラスチック及びその義歯床は、生態環境への悪影響がないばかりでなく、人体などへ積極的に好影響を与えるという効果がある。即ち、シルクの繊維構造を形成しているセリシンは粘膜疾患や皮膚疾患等に有効な薬理作用を発揮するものであり、例えば直接人体などに使用する義歯床等では、前記疾患を有する患者をはじめとする義歯床使用者の健康を維持・増進することができ、且つ医療費の抑制・削減を実現することができる。
【０１５２】
上記繊維強化プラスチックは生態環境に配慮した工業製品等に幅広く利用可能なものであり、前記繊維強化プラスチックを生産・普及することによって環境産業といえるような産業を勃興しうる。即ち、前記繊維強化プラスチックに必要なシルク繊維が生産されるため、繭、養蚕が不可欠となり、広範囲な桑畑が必要となる。そのため、休耕田が利用されて農業が盛んになり、農村地域の雇用が拡大される。さらに桑を植樹することにより緑が増加し、大気中のＣＯ_２が削減でき、落葉樹として土質の改善に寄与し、周辺水系の水質も改善できるという効果も期待できる。【Technical field】
[0001]
The present invention relates to a fiber reinforced plastic having high strength and having high adaptability to an ecological environment such as a human body and nature, and a denture base formed of the fiber reinforced plastic.
[Background]
[0002]
In modern society, plastic crystals continue to be consumed in large quantities from daily convenience to every corner of daily life, and life without plastic is hard to imagine, but it is bathed in its benefits. However, in recent years, some plastics have a high degree of convenience, but some of them have started to be recognized as dangerous and have become a social problem.
[0003]
Historically, plastic (PE) and polypropylene (PP) were originally used as plastics, have almost no toxicity, burn relatively cleanly when discarded and burned, and have a certain usefulness Met. Later, polyethylene (PE) and polypropylene (PP) were recognized as having problems in strength, etc., and improved plastics such as polyvinyl chloride (PVC) and polycarbonate (PC) produced from ethylene and chlorine. Polysulfone (PSF) and the like have been improved to a great extent in properties such as strength.
[0004]
However, when plastics made of organochlorine compounds such as polyvinyl chloride (PVC) are discarded and incinerated after production and consumption, there is a possibility that dioxins are generated by the high temperature during incineration and the chlorine contained in the plastics. is there. Dioxin has two toxicities, acute toxicity and chronic toxicity, and shows chronic toxicity such as carcinogenicity and teratogenicity by long-term intake of low concentrations of dioxin. For example, it is well known that dioxins are contained in dead leaves used during the Vietnam War, and that many malformed children were born after the war and cancer patients occurred.
[0005]
Furthermore, dioxins, bisphenol A (bis-A) constituting polycarbonate (PC) and polysulfone (PSF), phthalic acid compounds such as phthalic acid esters added as plasticizers to vinyl chloride, As an environmental hormone (endocrine disrupting chemical substance) that affects the endocrine function of humans, it has been pointed out. Such environmental hormones are being recognized as inhibiting the normal growth of living cells and having a great adverse effect on the human body and the natural environment. Towards the ecological environment caused by dioxins generated during incineration and eluted bisphenol A, etc. The influence of is worried.
[0006]
Therefore, along with the recent increase in recognition of the impact on the ecological environment, the newly provided plastics have characteristics such as strength, etc., which conventional plastics such as polyvinyl chloride (PVC) and polycarbonate (PC) have. It is highly desired that it has a high degree of adaptability to the ecological environment and can preserve the global environment and maintain human health.
[0007]
In particular, the above requirements are particularly strong for plastics that are used directly on the human body, such as denture bases, but polycarbonate resins and sulfone resins are used as materials for conventional denture bases, and polyvinyl chloride is used to further strengthen the strength. Sometimes mixed. Polycarbonate, polyvinyl chloride, and the like are plastics having the dangers as described above, and there is a strong concern that the human body may be adversely affected by leaving the current state of the denture base.
[0008]
Disclosure of the invention
The present invention has been made in view of the above-described problems, and exhibits high characteristics such as high strength and has high adaptability to an ecological environment, and aims to preserve the global environment and maintain human health. It is an object of the present invention to provide a fiber reinforced plastic that can be used, and a denture base made of the fiber reinforced plastic. The fiber-reinforced plastic and denture base of the present invention have no risk of generating chemical substances harmful to the ecological environment, such as dioxins and environmental hormones (endocrine disrupting chemical substances) generated during incineration, and properties such as strength It is highly functional.
[0009]
The fiber reinforced plastic according to the present invention uses a synthetic resin having a biocompatibility that can be said to be harmless to the ecological environment. For example, in a methyl methacrylate resin, polyethylene or polypropylene having a predetermined mechanical property and a predetermined biocompatibility. It is characterized by being formed by dispersing and adding a predetermined proportion of silk fibers. In the fiber-reinforced plastic, it is preferable that the silk fiber is in the form of a powdered crushed piece, a raw yarn shape, a twisted yarn shape, or a combination thereof. Furthermore, in the fiber reinforced plastic, In the pre-polymerization stage In methyl tacrylate resin , 6 Main twist 32 denier twist yarn of Mixed weight ratio of silk fiber 4.4 % To 15% Align the direction Dispersion addition After heat polymerization Once formed, again Melted polyethylene Of pellets Inside, two twisted 27 denier twisted yarn More than 4.4% blended silk fiber, or 4 twisted 29 denier twisted yarn More than 4.4% blended silk fiber, or 6 twisted 32 denier twisted yarn Align the direction of silk fiber with a mixing weight ratio of 2.2% or more Dispersion addition And then melt again, then press mold Once formed, again Melted polypropylene Of pellets Inside, two twisted 27 denier twisted yarn 4.4% mixed weight ratio of silk fiber, or 4 twisted 29 denier twisted yarn Align the direction of silk fiber with a mixing weight ratio of 2.2% Dispersion addition After that, press molding More preferably it is formed.
[0010]
Furthermore, the denture base according to the present invention uses a synthetic resin having biocompatibility that is harmless to the ecological environment. For example, a predetermined proportion of methyl methacrylate resin having a predetermined mechanical property and a predetermined biocompatibility is used. It is characterized by being formed by dispersing and adding silk fibers. Also in this case, it is preferable that the silk fiber is in the form of fine powder pieces, raw yarn shape, twisted yarn shape, or a combination thereof. Furthermore, in the denture base, when the silk fiber is any one of a 2-twisted 27 denier twisted yarn, a 4-twisted 29 denier twisted yarn, and a 6-twisted 32 denier twisted yarn, the mixing weight ratio is 2.2% to 15%. Is preferred. The fiber reinforced plastic and the denture base synthetic resin may be combined.
[0011]
The above fiber-reinforced plastic and its denture base are made of natural synthetic silk fiber with a synthetic resin that is harmless to the ecological environment, so that the strength and other properties can be improved, and the ecological environment such as the human body and nature can be improved. Is highly adaptable and safe.
[0012]
For example, when using methyl methacrylate resin, polyethylene, polypropylene, etc. as a base material, it has a strength equal to or higher than that of an organic chlorine compound and does not generate dioxin at the time of incineration or leak environmental hormones. Does not adversely affect the human body or natural environment. In particular, the fiber reinforced plastic using a methyl methacrylate resin as a base material has high strength, and the fiber reinforced material is inconspicuous and has high aesthetics, and is optimal as a material used directly on the human body such as a denture base. The fiber-reinforced plastic and its denture base of the present invention have the following merits in detail.
[0013]
(1) By improving strength, it is possible to create new products and improve product value. A product having a strength that could not be realized with ordinary methyl methacrylate resin (PMMA), polyethylene (PE), polypropylene (PP) or the like can be produced.
(2) Because it is made of silk and silk that does not produce harmful substances, it is harmless and useful. For example, vinyl chloride (PVC) or the like leaks toxicity contained in water or hot water, but the fiber reinforced plastic does not have such toxicity. It can be applied to a wide range of products that touch the skin of infants and carry them to their mouths, thus protecting the safety of users. Examples of products include toothbrushes, tableware, toys, and water-washing instruments.
(3) Silk fiber as a reinforcing material does not impair the aesthetics of products made of this fiber-reinforced plastic. Since the mixed reinforcing material has transparency and does not affect the aesthetics of the product, it is superior to the products using glass fiber or carbon fiber.
(4) In particular, for materials used directly on the human body, such as denture bases placed in the mouth, it is an essential condition that the material has high strength and is not toxic. This fiber reinforced plastic is most suitable because it positively affects the human body by pharmacological action against diseases.
[Brief description of the drawings]
[0014]
FIG. 1 is an explanatory view showing the fiber structure of silk,
FIG. 2 is a sectional view showing the structure of sericin,
FIG. 3 (a) is a partial perspective view showing silk which is a cotton-like 1.0 denier yarn,
FIG. 3 (b) is a partial perspective view showing a two-strand 27 denier silk.
FIG. 3 (c) is a partial perspective view showing a four-strand 29 denier silk,
FIG. 3 (d) is a partial perspective view showing a silk of 6-twisted 32 denier,
FIG. 4 is an explanatory view showing a test piece of methyl methacrylate resin (or polypropylene),
FIG. 5 is an explanatory view showing a polyethylene test piece,
FIG. 6 is a graph showing the relationship between the mixing weight ratio of powdered finely divided piece silk and the bending stress at maximum load when the base material is methyl methacrylate resin,
FIG. 7 is a graph showing the relationship between the mixture weight ratio of 1.0 denier silk of cotton-like raw yarn and the bending stress at maximum load when the base material is methyl methacrylate resin;
FIG. 8 is a graph showing the relationship between the mixed weight ratio of double twisted 27 denier silk and the bending stress at maximum load when the base material is methyl methacrylate resin;
FIG. 9 is a graph showing the relationship between the mixed weight ratio of 4-twisted 29 denier silk and the bending stress at maximum load when the base material is methyl methacrylate resin;
FIG. 10 is a graph showing the relationship between the mixed weight ratio of 6-twisted 32 denier silk and the bending stress at maximum load when the base material is methyl methacrylate resin;
FIG. 11 is a graph showing the relationship between the mixed weight ratio of each added silk and the bending stress at maximum load when the base material is methyl methacrylate resin;
FIG. 12 is a graph showing the relationship between the mixed weight ratio of powdered finely divided piece silk and the maximum load tensile stress when the base material is polyethylene,
FIG. 13 is a graph showing the relationship between the blended weight ratio of 1.0 denier silk and the tensile stress at maximum load when the base material is polyethylene.
FIG. 14 is a graph showing the relationship between the mixed weight ratio of two twisted 27 denier silk and the tensile stress at maximum load when the base material is polyethylene,
FIG. 15 is a graph showing the relationship between the mixed weight ratio of four-strand 29 denier silk and the tensile stress at maximum load when the base material is polyethylene.
FIG. 16 is a graph showing the relationship between the mixed weight ratio of six-twisted 32 denier silk and the tensile stress at maximum load when the base material is polyethylene.
FIG. 17 is a graph showing the relationship between the mixed weight ratio of each added silk and the tensile stress at maximum load when the base material is polyethylene,
FIG. 18 is a graph showing the relationship between the test piece elongation at the maximum load and the tensile stress at the maximum load when the base material is polyethylene,
FIG. 19 is a graph showing the relationship between the mixed weight ratio of powdered finely divided piece silk and the bending stress at maximum load when the base material is polypropylene,
FIG. 20 is a graph showing the relationship between the blended weight ratio of 1.0 denier silk and the bending stress at maximum load when the base material is polypropylene.
FIG. 21 is a graph showing the relationship between the mixed weight ratio of two-strand 27 denier silk and the bending stress at maximum load when the base material is polypropylene.
FIG. 22 is a graph showing the relationship between the mixed weight ratio of four-twisted 29 denier silk and the bending stress at maximum load when the base material is polypropylene.
FIG. 23 is a graph showing the relationship between the mixed weight ratio of 6-twisted 32 denier silk and the bending stress at maximum load when the base material is polypropylene.
FIG. 24 is a graph showing the relationship between the mixing weight ratio of each added silk and the bending stress at maximum load when the base material is polypropylene,
FIG. 25 is a schematic diagram of the anti-breaking test,
FIG. 26 is a graph showing the analysis results according to the amount of silk added to the composite plastic when the added silk is a powdered piece;
FIG. 27 is a graph showing the analysis result according to the amount of silk added to the composite plastic when the added silk is 1.0 denier of cotton-like raw yarn;
FIG. 28 is a graph showing the analysis results according to the amount of silk added to the composite plastic when the added silk is 2 twisted 27 denier,
FIG. 29 is a graph showing the analysis results according to the amount of silk added to the composite plastic when the added silk is 4 twisted 29 denier,
FIG. 30 is a graph showing the analysis results according to the amount of silk added to the composite plastic when the added silk is 6-twisted 32 denier,
FIG. 31 is a graph showing the analysis results according to the silk shape when the silk addition amount is 0.1 g (mixing weight ratio 0.55%);
FIG. 32 is a graph showing the analysis results according to the silk shape when the silk addition amount is 0.4 g (mixing weight ratio 2.2%).
FIG. 33 is a graph showing the analysis results according to the silk shape when the silk addition amount is 0.8 g (mixing weight ratio 4.4%).
BEST MODE FOR CARRYING OUT THE INVENTION
[0015]
The embodiments of the fiber reinforced plastic and the denture base according to the present invention will be described based on examples, but the present invention is not limited to the following embodiments and examples. In particular, the synthetic resin used for the fiber reinforced plastic and its denture base is appropriate as long as it is a synthetic resin harmless to the ecological environment other than those shown in the examples. Further, the shape, thickness, length, and mixing weight ratio of the silk fiber dispersed / added to the fiber reinforced plastic are appropriate as long as they are within the scope of the present invention other than those shown in the examples. This includes the case of adding what is contained.
[0016]
As a premise, the characteristics and properties of the fiber reinforced plastic of the present invention and silk fibers mixed and added to the denture base will be described. Silk is made by releasing the protein produced by the cocoon from the spout to the outside, and the cross-sectional shape of the silk fiber and the chemical structure of the protein are complex. It will be a factor to cause.
[0017]
FIG. 1 is an explanatory view showing the fiber structure of silk, and FIG. 2 is a cross-sectional view showing the structure of sericin. As shown in FIG. 1, the silk fiber structure is configured such that one raw yarn 3 is formed in a shape in which a glue-like sericin 2 is wrapped around two fibroin fibers 1. One fibroin fiber 1 has about 900 to 1400 spiral microfibrils 1b made of fibroin molecules 1a and having a thickness of 0.2 to 0.4 .mu.b. The microfibrils 1b constitute fibers. The fibril 1c, which is a basic structural unit, is configured.
[0018]
The sericin 2 wrapping the fibroin fiber 1 has a layered structure as shown in FIG. 2 when enlarged, and from the outside, the I layer 2a of the sericin 2, the mixed layer 2b of the I layer 2a and the II layer 2c, the II layer 2c, It has a six-layer structure of III layer 2d, IV layer 2e, and V layer 2f. Each layer 2a to 2f of sericin 2 has its own characteristics in each layer and the entire six layers, and all of them are important for silk fibers. For example, in order to protect the living body in the cage, it works to protect the inside in response to changes in the outside air and changes in the outside environment.
[0019]
Here, the characteristic compared with the other natural fiber of a silk fiber is shown. Table 1 is a characteristic comparison table between silk and other natural fibers. In Table 1, d: denier of Young's modulus unit g / d is a unit representing the thickness of a fiber, and one having a weight of 450 m and a weight of 50 mg is 1 denier. Unit of impact cutting energy Erg / cm ² Erg: The erg is a work performed when a force of 1 dyn acts on an object and the point of action moves 1 cm in the direction of the force.
[0020]
[Table 1]

[0021]
As shown in Table 1, compared to cotton and wool, silk fibers have a high Young's modulus and are difficult to deform, have high impact shear energy and are strong, have a high decomposition point temperature, and have excellent heat resistance. It has the characteristics that silk fibers are superior in overall physical properties compared to other natural fibers. Synthetic fibers are decomposed, melted and burned around 200 ° C to generate toxic gases, but silk fibers are not burned at 300 to 400 ° C to generate toxic gases, and are strong, safe and cost-effective. Are better. Furthermore, even when added to the base material, it has high permeability and does not cause white turbidity, etc., hardly changes in the color tone, color, etc. of the base material, and it is not noticeable even if mixed in the base material, so it is highly aesthetic. Fiber reinforced plastics can be manufactured.
[0022]
Furthermore, silk fibers not only have characteristics such as high strength, but also have a positive effect on the ecological environment such as the human body. In other words, silk fibers have been regarded as useful from the ancient times because of their beauty and softness, but today, sericin, a silk mantle, is effective for mucosal and skin diseases. The pharmacological effect is scientifically proven, and it can be said to be the most suitable “environmental material” as a material to be applied directly to the human body. Silk fibroin also has good compatibility with living organisms and is optimal as a biomaterial.
[0023]
And the shape and thickness of the silk fiber added to the synthetic resin of the base material in the experimental examples to be described later are powdered finely crushed pieces (thickness of 1 mm or less of raw yarn), cotton-like 1.0 denier raw yarn (thickness) There are 5 types: 2 twisted 27 denier twisted yarn (approx. 270 μm thick), 4 twisted 29 denier twisted yarn (approx. 290 μm thick), 6 twisted 32 denier twisted yarn (thickness approx. 320 μm) . The length of the silk is 2 twisted 27 denier twisted yarn, 4 twisted 29 denier twisted yarn, and 6 twisted 32 denier twisted yarn, all suitable lengths of 10 mm or more based on the dimension in the major axis direction of the test piece. Say it. A shape of the silk other than powdered fine fragments is shown in FIG. FIG. 3A is a partial perspective view showing a silk fiber which is a cotton-like 1.0 denier yarn, and FIG. 3B is a partial perspective view showing a silk fiber which is a double-twisted 27 denier twist yarn. c) is a partial perspective view showing a silk fiber which is a twisted yarn of 4 deniers and 29 deniers, and FIG. 8D is a partial perspective view showing a silk fiber which is a twisted yarns of 6 deniers and 32 denier.
[0024]
Examples of fiber reinforced plastics and denture bases obtained by mixing and adding the above five types of silk fibers to a synthetic resin as a base material will be described below.
[0025]
[Example 1]
The test piece of fiber reinforced plastic uses methyl methacrylate resin (PMMA) as a base material of synthetic resin, finely pulverized fragments, cotton-like 1.0 denier raw yarn, 2 twisted 27 denier twisted yarn, 4 twisted 29 denier Five types of silk fibers, twisted yarns and 6-twisted 32 denier twisted yarns, were each dispersed and added to 18.0 g of the methyl methacrylate resin. The test piece is molded into a standard size and shape according to JIS K7203 (hard plastic bending test). FIG. 4 is an explanatory view showing a manufactured test piece of methyl methacrylate resin, which is finished to a rectangle of 110 mm × 10 mm × 4 mm, which is the prescribed size and shape of the test piece of JIS K7203.
[0026]
Table 2 shows the mixing amount and mixing weight ratio of the silk fibers dispersed and added to the methyl methacrylate resin. Since the cotton-like 1.0 denier yarn is bulky, the mixing amount / mixing weight ratio is set to 1/10 of the mixing amount / mixing weight ratio of other silks.
[0027]
[Table 2]

[0028]
In the production of the test piece, a prototype of an aluminum plate having a thickness of 4 mm, a length of 110 mm, and a width of 21 mm is produced, and plaster is filled in a mold serving as a mold, and the prototype is buried. The mold form can be divided into two later, and the center of the thickness of the aluminum plate (original mold) is positioned on the dividing line, and the mold is embedded in gypsum twice. In addition, a separating material (synthetic neutral detergent) is applied to the plaster on the lower surface so that the upper and lower gypsums are separated from the gypsum of the mold to be buried. After the plaster is cured, the upper and lower molds and the plaster are divided and the original aluminum plate is taken out. The gypsum mold for producing the test piece in the above process is completed. On the inner surface of the finished gypsum mold, a sodium alginate-based separating material is applied as a separating material for the test piece material and the gypsum and dried sufficiently.
[0029]
The methyl methacrylate resin used as the base material of the test piece is manufactured from polymer powder and monomer liquid. The composition of the polymer powder is fine powdery PMMA (polymethyl methacrylate / polymer) 99.0 to 99.3%, benzoyl peroxide (polymerization initiator) 0.2 to 0.5%, colorant 0.5 The composition of the monomer liquid is MMA (monomethyl methacrylate / monomer) 84-100%, EDMA (ethylene glycol dimethacrylate / crosslinking agent) 0-16%, hydroquinone (polymerization inhibitor) 0.005. %. Isoresin H manufactured by Hydental Japan Co., Ltd. was used for the production of the test piece of this example.
[0030]
When 77.4 ml of the monomer liquid is mixed with 180 g of the polymer powder, a bowl-like prepolymerization stage starts after about 15 minutes at room temperature of 23 ° C. The gypsum mold divided into the upper and lower parts in the pre-polymerization stage having sufficient plasticity is filled up and down evenly, and each kind of silk aligned in the long direction in the meantime is relative to the long axis direction (110 mm direction) of the test piece. It is dispersed in a predetermined weight ratio and added in parallel. The finely divided silk fibers are previously mixed in the polymer powder. After that, the gypsum mold is put together through a polyethylene film to give 5 kgf / cm @-. ³ After the test pressure, the gypsum mold is divided to remove excess filler. Thereafter, the gypsum molds are combined without using a polyethylene film, bonded at the same pressure as the test pressure, heated and polymerized by a dry polymerization method, heated at 100 ° C. for about 15 minutes and then slowly cooled to take out the test piece material. After completion of the polymerization, the test piece material is cut to a specified size to complete the test piece.
[0031]
And the anti-breaking test by JISK7203 (hard plastic bending test) was done with respect to the test piece obtained at the said manufacture process. The test equipment is an Instron universal testing machine, Shimadzu AG-5000A (owned by Shiga Prefectural Industrial Laboratory), and the test setting conditions are test form SINGLE BEND (unidirectional bending test), test indenter moving speed 20.000 mm / Min, test indenter 20.000 KGF, distance between fulcrums 80.000 mm. An anti-breaking test was performed under the set conditions, and data was obtained by testing each of the four test pieces for each silk mixing condition (one of which cannot be tested). For comparison, data were also obtained from test pieces of methyl methacrylate resin and polysulfone resin without addition of silk. Tables 3 to 7 show the maximum load values (bending stress values) by the anti-breaking test according to each silk mixing condition. The unit of the maximum load value (bending stress value) in the table is MPa.
[0032]
[Table 3]

[0033]
[Table 4]

[0034]
[Table 5]

[0035]
[Table 6]

[0036]
[Table 7]

[0038]
The test results of Tables 3 to 7 are shown in the graph. FIG. 6 is a graph showing the relationship between the mixed weight ratio of powdered finely crushed silk and the bending stress at maximum load, and FIG. 7 is the relationship between the mixed weight ratio of cotton-like raw yarn 1.0 denier silk and the bending stress at maximum load. FIG. 8 is a graph showing the relationship between the mixed weight ratio of two-twisted 27 denier silk and the bending stress at maximum load, and FIG. 9 is the mixed weight ratio of four-twisted 29 denier silk and the bending stress at maximum load. FIG. 10 is a graph showing the relationship between the mixed weight ratio of 6-twisted 32 denier silk and the bending stress at maximum load. FIG. 11 is a powdered crushed piece, 2 twisted 27 denier, 4 twisted 29. It is a graph which shows the relationship between the mixing weight ratio of each addition silk of denier and 6 twist 32 denier, and the bending stress at the time of a maximum load. 6 to 11, the alternate long and short dash line indicates the bending stress of the methyl methacrylate resin without addition of silk, and the broken line indicates the bending stress of the polysulfone resin.
[0039]
Judging from the test results of FIGS. 6 to 11, the methyl methacrylate resin added with silk fibers has improved bending stress and increased strength compared to the methyl methacrylate resin without addition of silk. In particular, when four types of cotton-like raw yarn 1.0 denier, 2 twisted 27 denier twisted yarn, 4 twisted 29 denier twisted yarn, 6 twisted 32 denier twisted yarn are mixed, the silk-free methyl methacrylate resin (FIG. 11) As shown in the area above the one-dot chain line), the strength increased reliably and markedly, and the strength was improved by bending stress of 59.3% at the maximum, confirming the effectiveness of the fiber reinforced plastic added with silk fibers. It was done. Further, when the silk fiber was a raw yarn / twisted yarn and the mixing weight ratio was 2.2% or more, the improvement in strength was more remarkable in both cases.
[0040]
As the blended weight ratio of the added silk fibers increases to 0.55%, 2.2%, and 4.4%, the strength improves and a strength due to bending stress comparable to that of polysulfone resin can be obtained. As shown in FIG. 10, when the mixing weight ratio of the six-twisted 32 denier twisted yarn is 15%, the strength tends to be lower than when it is 4.4%. In this case, it is considered that there is an optimum mixing weight ratio of silk between 4.4% and 15% in the 6-twisted 32 denier twisted yarn. As another tendency, as the thickness of the added silk fiber is increased, the strength due to bending stress is improved and the stability of the test data is observed. Although it was 1/10 as compared with the added silk fiber, an improvement in strength due to remarkable bending stress was confirmed.
[0041]
[Example 2]
The test piece of fiber reinforced plastic uses polyethylene (PE) as a base material of synthetic resin, powdered finely divided pieces, cotton-like 1.0 denier raw yarn, 2 twisted 27 denier twisted yarn, 4 twisted 29 denier twisted yarn, 6 Five types of silk fibers of the main twisted 32 denier twisted yarn were mixed with 4.0 g of the polyethylene, respectively. The test piece is molded in standard dimensions and shape in accordance with JIS K7113 (plastic tensile test method) type 2 test piece. FIG. 5 is an explanatory view showing a polyethylene test piece. The test piece has a JIS K7113 stipulated size and shape, a total length A115 mm, a width B25 ± 1 mm at both ends, a parallel part length C33 ± 2 mm, and a parallel part width D6 ±. It is finished to 0.4 mm, small radius E14 ± 1 mm, large radius F25 ± 2 mm, distance between marked lines G25 ± 1 mm, distance between grips H80 ± 5 mm, and thickness I1 to 3 mm.
[0042]
Table 8 shows the mixing amount and mixing weight ratio of silk fibers to be mixed with the base material polyethylene. Since the cotton-like 1.0 denier yarn is bulky, the mixing amount / mixing weight ratio is set to 1/10 of the mixing weight ratio of other silk fibers.
[0043]
[Table 8]

[0044]
In manufacturing the test piece, a mold that is divided in two by a concave surface and a smooth surface is manufactured in advance. In addition, Novatec LL film grade UF240 (manufactured by Nippon Polychem Co., Ltd.) is used for polyethylene as a base material of the test piece. The characteristics of the UF240 are MFR (degree of flow) 2.1 g / 10 min, density 0.920 g / cm. ³ (LDPE (linear low density polyethylene)), melting point (melting end point) 124 ° C., softening temperature 100 ° C., no additive aids added.
[0045]
Prepare 4.0 g of base material pellets and silk fibers adjusted to the specified weight ratio to match the size and shape of the specimen in the longitudinal direction, and evenly dissolve a part of the base material pellets in the concave surface of the mold And melt in an electric furnace at 140 ° C. and press with a spatula so that there are no bubbles. Then, silk is dispersed and added in the long direction. The silk is added so that the silk is evenly distributed over the entire test piece having a total length A of 115 mm based on the length C: 33 mm of the parallel portion in FIG. Thereafter, the remaining pellets are coated, melted again in an electric furnace at 140 ° C., and the base material melted with a spatula is made to conform to silk fibers. Then, 5kgf / cm ³ The test piece is completed by adjusting to the specified dimensions and shape, such as removing excess parts, by pressing at a pressure of ℃ and gradually cooling after pressure forming.
[0046]
A tensile test according to JIS K7113 (plastic tensile test method) was performed on the test piece obtained in the manufacturing process. A universal tensile tester (5t) INSTRON 5569 (owned by the Tohokubu Industrial Center, Shiga Prefecture) is used as the test equipment, and the test setting conditions are test form pull, crosshead speed 20.000 mm / min, full scale load range 50 kg (test The load range was changed because part of the piece exceeded the load range: 5000 kg), and the distance between the grips of the test piece was 80 mm. A tensile test was conducted under the above-mentioned setting conditions, and for each silk mixing condition, data on tensile stress (MPa) at the maximum load and test piece elongation (mm) at the maximum load, and a polyethylene test without addition of silk as a comparison target Similar data from the pieces were obtained. Tables 9 to 13 show data on tensile stress (MPa) at the maximum load according to the tensile test for each silk mixing condition, and Tables 14 to 18 show data on elongation (mm) of the test piece at the maximum load corresponding to this. Shown in
[0047]
[Table 9]

[0048]
[Table 10]

[0049]
[Table 11]

[0050]
[Table 12]

[0051]
[Table 13]

[0052]
[Table 14]

[0053]
[Table 15]

[0054]
[Table 16]

[0055]
[Table 17]

[0056]
[Table 18]

[0057]
The test result regarding the tensile stress (MPa) at the maximum load of the said Table 9-Table 13 is shown on a graph. FIG. 12 is a graph showing the relationship between the mixed weight ratio of powdered finely crushed silk and the maximum load tensile stress, and FIG. 13 is the relationship between the mixed weight ratio of cotton-like raw yarn 1.0 denier silk and the maximum load tensile stress. FIG. 14 is a graph showing the relationship between the mixed weight ratio of two-twisted 27 denier silk and the tensile stress at maximum load, and FIG. 15 is the mixed weight ratio of four-twisted 29 denier silk and the tensile stress at maximum load. FIG. 16 is a graph showing the relationship between the mixed weight ratio of 6-twisted 32 denier silk and the tensile stress at maximum load, and FIG. 17 is a powdered crushed piece, 2 twisted 27 denier, 4 twisted 29 It is a graph which shows the relationship between the mixing weight ratio of each addition silk of denier and six twist 32 denier, and the tensile stress at the time of a maximum load. 12-17, the broken line, the dashed-dotted line, and the dashed-two dotted line have shown the tensile stress at the time of the maximum load of the polyethylene resin without a silk.
[0058]
12 to 17, in the case of 2-twisted 27-denier twisted yarn, 4-twisted 29-denier twisted yarn, and 6-twisted 32 denier twisted yarn, the strength related to the tensile stress of the fiber-reinforced plastic is increased as the amount of addition of the silk fiber is sequentially increased. Markedly increased, and particularly in the case of 6-twisted 32 denier twisted yarn, the strength related to tensile stress is extremely increased.
[0059]
Further, FIG. 18 is a graph showing the correspondence between the tensile stress (MPa) at the maximum load shown in Tables 9 to 13 and the test piece elongation (mm) at the maximum load shown in Tables 14 to 18. Shown in In FIG. 18, ◯ is powdered finely divided piece silk, ◎ is cotton-like 1.0 denier raw silk, □ is 2 twisted 27 denier twisted silk, Δ is 4 twisted 29 denier twisted silk, and ■ is 6 twisted 32 Denier twisted silk and ◇ indicate the test results of polyethylene with no silk added.
[0060]
When examining FIG. 18, the silk-free polyethylene has an elongation (displacement) of the test piece of about 300 mm or more when the tensile stress (MPa) at the maximum load is applied. When the tensile stress at the maximum load is applied, the elongation of the test piece shifts to a range of 10 mm or less. This tendency is seen from 2.2% or more of 2-twisted 27 denier twisted yarn, 2.2% or more of 4-twisted 29 denier twisted yarn, and 0.5% or more of 6-twisted 32 denier twisted yarn, and 2 twisted 27 denier twisted yarn 4.4% or more of 4-twisted 29 denier twisted yarn and 4.4% or more of 6-twisted 32 denier twisted yarn, the tensile strength is dramatically improved and the test is performed at the maximum load. The single elongation is also suppressed to 11 mm or less. Therefore, it is recognized that the addition of silk fibers is effective in improving the strength of the fiber reinforced plastic, and it can be seen that the strength of the fiber reinforced plastic is improved particularly with an increase in the thickness and amount of the silk fiber.
[0061]
[Example 3]
The test piece of fiber reinforced plastic uses polypropylene (PP) as a base material of synthetic resin, powdered finely crushed pieces, cotton-like 1.0 denier raw yarn, 2 twisted 27 denier twisted yarn, 4 twisted 29 denier twisted yarn, 6 Five types of silk fibers of a main twisted 32 denier twisted yarn were mixed with 4.1 g of the polypropylene, respectively. Test specimens were prepared in standard dimensions and shapes according to JIS K7203 (plastic bending test method). FIG. 5 is an explanatory view showing a test piece made of polypropylene, and the test piece is finished in a rectangular shape of 110 mm × 10 mm × 4 mm with a prescribed size and shape of JIS K7203.
[0062]
Table 19 shows the mixing amount and mixing weight ratio of the silk fibers mixed with the base material polypropylene. Since the cotton-like 1.0 denier yarn is bulky, the mixing amount / mixing weight ratio is set to 1/10 of the mixing weight ratio of other silk fibers.
[0063]
[Table 19]

[0064]
In the production of the test piece, a mold that can be divided into two parts composed of a concave surface is produced in advance. Novatec PP injection molding grade MA03 (manufactured by Nippon Polychem Co., Ltd.) is used as the base material of the test piece. The characteristics of MA03 are as follows: MFR (degree of flowability) 25 g / 10 min, density 0.910 to 0.920 g / cm. ³ The melting point (melting end point) is 163 ° C.
[0065]
Prepare 4.1g of base material pellets and silk adjusted to the specified weight ratio according to the size and shape of the test piece in the long direction so that the base material pellets are even when dissolved in the concave surface of the mold Then, melt in an electric furnace at 165 ° C., and press with a spatula so that there are no bubbles. Thereafter, the silk is dispersed and added so as to be even in parallel to the long axis direction (110 mm direction) of the test piece, and the excess silk is cut out from the test piece and the base material dissolved using a spatula is added. Accustom to silk fiber. Then, 5kgf / cm ³ The test piece is completed by adjusting to the specified size and shape, such as by removing the surplus portion by removing the surplus part by pressing at a pressure of ℃ and gradually cooling after press molding.
[0066]
The test piece obtained in the above production process was subjected to an anti-destructive test according to JIS K7203 (hard plastic bending test method). Instron type universal testing machine ORIENTEC RTC-1350A (owned by Shiga Prefectural Industrial Laboratory) is used as the test equipment. Test setting conditions are test form SINGLE BEND (unidirectional bending test), test indenter moving speed 20.000 mm / The test indenter was 20.000 KGF, and the distance between fulcrums was 80.000 mm. An anti-breaking test was carried out under the set conditions, and data were obtained by testing each of the four test pieces for each silk mixing condition. For comparison purposes, data were also obtained from polypropylene test specimens without addition of silk. Tables 20 to 24 show the maximum load values (bending stress values) by the anti-breaking test according to the silk mixing conditions. The unit of the maximum load value (bending stress value) in the table is MPa.
[0067]
[Table 20]

[0068]
[Table 21]

[0069]
[Table 22]

[0070]
[Table 23]

[0071]
[Table 24]

[0072]
The test result regarding the bending stress (MPa) at the time of the maximum load of the said Table 20-Table 24 is shown on a graph. FIG. 19 is a graph showing the relationship between the mixed weight ratio of powdered finely crushed silk and the bending stress at maximum load, and FIG. FIG. 21 is a graph showing the relationship between the mixed weight ratio of two twisted 27 denier silks and the bending stress at maximum load, and FIG. 22 is the mixed weight ratio of four twisted 29 denier silks and the bending stress at maximum load. FIG. 23 is a graph showing the relationship between the mixed weight ratio of 6-twisted 32 denier silk and the bending stress at the maximum load, and FIG. 24 is a powdered crushed piece, 2 twisted 27 denier, 4 twisted 29 It is a graph which shows the relationship between the mixing weight ratio of each addition silk of denier and 6 twist 32 denier, and the bending stress at the time of a maximum load. 19 to 24, the broken line, the alternate long and short dash line, the alternate long and two short dashes line, and the dotted line indicate the bending stress at the maximum load of the polypropylene with no silk added.
[0073]
When FIG. 24 is examined, the strength improvement regarding the bending stress of the fiber reinforced plastic was recognized also in the present Example in which silk fiber was added to polypropylene. In particular, the improvement in strength was remarkable at 4.4% for 2 twisted 27 denier yarn and 2.2% for 4 twisted 29 denier twisted yarn. When polypropylene is used as a base material, the effectiveness of improving the strength of adding silk fibers appears in a form with a gentle quadratic curve.
[0074]
[Example 4]
In this example, in order to verify the strength improvement of the fiber reinforced plastic from various perspectives, the strength test of multiple test pieces was performed. For the base material, methyl methacrylate resin, which is a typical plastic that does not adversely affect the human body and natural environment, is used, and silk fibers are dispersed and added to the fiber reinforced plastic test piece. In the same manner as in the above example, the test piece was considered in consideration of the influence of the mixed state of the silk on the strength of the fiber reinforced plastic, and the mixed amount (or weight) of the silk while experimentally changing the thickness, length, shape, etc. of the silk. The ratio was changed.
[0075]
Specifically, five kinds of silk fibers having dimensions suitable for the test piece were dispersed and added to 18.0 g of methyl methacrylate resin as a base material to produce a test piece. The shape of the silk fiber to be added is powdered crushed pieces (raw yarn of 1 mm or less), cotton-like 1.0 denier raw yarn, 2 twisted 27 denier twisted yarn, 4 twisted 29 denier twisted yarn, 6 twisted 32 denier A twisted yarn was applied and mixed with the base material evenly to apply pressure. The silk mixing amount (mixing weight ratio) is as shown in Table 25. For comparison, a comparative test piece of polysulfone resin and methyl methacrylate resin without addition of silk was produced, and the same experiment was attempted on the comparative test piece.
[0076]
[Table 25]

[0077]
The strength test of the test piece was performed by an anti-destructive test based on the industrial standard of JIS K7203 (bending test method of hard plastic). In order to carry out the bending test, the test piece was prepared by uniformly dispersing and mixing the silk with the base material as described above, and cooling was completed. This was measured using the standard dimensions (110 mm × 10 mm ×) defined in the bending test method. 4 mm) and manufactured according to the mixing weight ratio of each silk. The test equipment uses an Instron universal testing machine (Autograph AG-5000A, manufactured by Shimadzu Corporation), which is a Shiga industrial test place-owned equipment, and the setting conditions of the testing machine are SINGLEBEND (unidirectional) Bending test), test indenter moving speed (TEST SPEED) was 20.000 mm / min, and test indenter load (F / S LOAD) was 20.000 KGF (196.133 N). FIG. 25 shows a schematic diagram of the anti-breaking test.
[0078]
By carrying out the anti-destructive test, the following data on strength were obtained. From the stress-strain relationship based on this data, the material properties of the fiber reinforced plastic are judged.
(A) Maximum value (MAX). Each value when the maximum load is applied to the test piece which is a material before the yield point where the elongation starts to increase rapidly without increasing the stress.
(B) Breaking value (BREAK). Each value when a load is applied and the test piece is bent after the yield point where the elongation starts to increase rapidly without increasing the stress of the test piece.
(C) Maximum limit value (LOAD KGF). It is a load value when the stress of the test piece reaches a peak. Since the bending load is applied here, it is the load of the bending strength of the test piece. The unit is shown in terms of N: Newton (1 kgf = 9.80665N).
(D) Bending value (ELONG MM). The distance traveled by the indenter, the unit is mm.
(E) Bending stress (STRESS KGF / MM ² ). The unit is shown in terms of MPa (1 MPa = 9.80665N).
(F) Elongation value (STRAIN%). When stress is generated by applying a load to the test piece, the molecules and molecules constituting the material of the test piece move and the test piece is deformed. The elongation value is the ratio of this deformation amount (bending made by the original plane of the specimen and the deformed plane).
[0079]
Below, the experiment example which performed the anti-breaking test of the test piece by changing the shape and addition amount of the silk to mix and add is shown. The base material of the test piece is a methyl methacrylate resin.
[0080]
(Experiment No. 1) Table 26 shows the test results when 0.1 g (0.55%) of finely pulverized silk was added to the base material amount of 18.0 g.
[0081]
[Table 26]

[0082]
(Experiment No. 2) Table 27 shows the test results when 0.4 g (2.2%) of finely pulverized silk was added to 18.0 g of the base material.
[0083]
[Table 27]

[0084]
(Experiment No. 3) Table 28 shows the test results when 0.8 g (4.4%) of finely pulverized silk was added to 18.0 g of the base material.
[0085]
[Table 28]

[0086]
(Experiment No. 4) Table 29 shows the test results in the case where 0.01 g (0.055%) of 1.0 denier cotton yarn is added to the base material amount of 18.0 g.
[0087]
[Table 29]

[0088]
(Experiment No. 5) Table 30 shows the test results obtained when 0.04 g (0.22%) of silk, which is a 1.0 denier cotton-like raw material, was added to the base material amount of 18.0 g.
[0089]
[Table 30]

[0090]
(Experiment No. 6) Table 31 shows the test results obtained when 0.08 g (0.44%) of 1.0 denier cotton-like raw yarn was added to 18.0 g of the base material.
[0091]
[Table 31]

[0092]
(Experiment No. 7) Table 32 shows the test results obtained when 0.1 g (0.55%) of 27 denier (double twisted) silk was added to the base material amount of 18.0 g.
[0093]
[Table 32]

[0094]
(Experiment No. 8) Table 33 shows the test results obtained when 0.4 g (2.2%) of 27 denier (double twisted) silk was added to 18.0 g of the base material.
[0095]
[Table 33]

[0096]
(Experiment No. 9) Table 34 shows the test results in the case of adding 0.8 g (4.4%) of 27 denier (twisted) silk to 18.0 g of the base material.
[0097]
[Table 34]

[0098]
(Experiment No. 10) Table 35 shows the test results obtained when 0.1 g (0.55%) of 29-denier (4-twisted) silk was added to the base material amount of 18.0 g.
[0099]
[Table 35]

[0100]
(Experiment No. 11) Table 36 shows the test results obtained when 0.4 g (2.2%) of 29-denier (4-twisted) silk was added to the base material amount of 18.0 g.
[0101]
[Table 36]

[0102]
(Experiment No. 12) Table 37 shows the test results in the case of adding 0.8 g (4.4%) of 29 denier (4-twisted) silk to 18.0 g of the base material.
[0103]
[Table 37]

[0104]
(Experiment No. 13) Table 38 shows the test results when 0.1 g (0.55%) of 32 denier (six strands) silk was added to the base material amount of 18.0 g.
[0105]
[Table 38]

[0106]
(Experiment No. 14) Table 39 shows the test results in the case of adding 0.4 g (2.2%) of 32 denier (6-twisted) silk to 18.0 g of the base material.
[0107]
[Table 39]

[0108]
(Experiment No. 15) Table 40 shows the test results obtained when 0.8 g (4.4%) of 32 denier (6-twisted) silk was added to 18.0 g of the base material.
[0109]
[Table 40]

[0110]
(Experiment No. 16) Table 41 shows the test results when 2.7 g (15%) of 32 denier (six strands) silk is added to the base material amount of 18.0 g.
[0111]
[Table 41]

[0112]
(Experiment No. 17) As a comparative example, Table 42 shows the test results of a polysulfone resin test piece having specified dimensions.
[0113]
[Table 42]

[0114]
(Experiment No. 18) As a comparative example, Table 43 shows the test results of a test piece of methyl methacrylate resin having specified dimensions.
[0115]
[Table 43]

[0116]
Next, Tables 44 to 48 and FIGS. 26 to 30 show tables and graphs according to the silk shapes mixed and added based on the experimental results. The data of the test results in Tables 44 to 48 and FIGS. 26 to 30 are the maximum limit value (unit: N), bending value (unit: mm), bending stress (unit: MPa), elongation value (unit:%). The maximum value (MAX) is adopted as each value. For comparison, the test results of polysulfone resin and methyl methacrylate resin (without addition of silk), which are comparative test pieces, are also shown in the table and graph.
[0117]
(I) Table 44, FIG. 26 (a), and FIG. 26 (b) show the analysis results according to the amount of silk added to the composite plastic when the added silk is powdered crushed pieces.
[0118]
[Table 44]

[0119]
(Ii) Table 45, FIG. 27 (a), and FIG. 27 (b) show the analysis results according to the amount of silk added to the composite plastic when the added silk is 1.0 denier of cotton-like raw yarn.
[0120]
[Table 45]

[0121]
(Iii) Table 46, FIG. 28 (a), and FIG. 28 (b) show the analysis results according to the amount of silk added to the composite plastic when the added silk is a double twisted 27 denier.
[0122]
[Table 46]

[0123]
(Iv) Table 47, FIG. 29 (a), and FIG. 29 (b) show the analysis results according to the amount of silk added to the composite plastic when the added silk is 29-denier with 4 twists.
[0124]
[Table 47]

[0125]
(V) Table 48, FIG. 30 (a), and the same figure (b) show the analysis result according to the amount of silk addition of the composite plastic when the added silk is 6-twisted 32 denier.
[0126]
[Table 48]

[0127]
Further, based on the above experimental results, Tables 49 to 51 and FIGS. 31 to 33 show tables and graphs for each mixed weight ratio (addition amount) of dispersed and added silk fibers. The test result data of Table 49 to Table 51 and FIGS. 31 to 33 are the maximum limit value (unit: N), bending value (unit: mm), bending stress (unit: MPa), elongation value (unit:%). The maximum value (MAX) is adopted as each value. For comparison, the test results of polysulfone resin and methyl methacrylate resin (without addition of silk), which are comparative test pieces, are also shown in the table and graph. For convenience, the mixing weight ratios of the cotton-based yarn 1.0 denier silk are 0.055%, 0.22%, and 0.44%, respectively. The mixing weight ratios are 0.55%, 2.2%, and 4.4%. Tables and graphs were included, and a 6% twisted 32 denier silk mixed weight ratio of 15% (added amount 2.7 g) was displayed in all tables and graphs.
[0128]
(I) Table 49, FIG. 31 (a), and FIG. 31 (b) show the analysis results corresponding to the silk shape when the amount of added silk is 0.1 g (mixing weight ratio 0.55%). The addition amount of 1.0 denier cotton-like raw yarn is 0.01 g (mixing weight ratio 0.055%).
[0129]
[Table 49]

[0130]
(Ii) Table 50, FIG. 32 (a), and FIG. 32 (b) show the analysis results according to the silk shape when the silk addition amount is 0.4 g (mixing weight ratio 2.2%). The addition amount of 1.0 denier cotton-like raw yarn is 0.04 g (mixing weight ratio 0.22%).
[0131]
[Table 50]

[0132]
(Iii) Table 51, FIG. 33 (a), and FIG. 33 (b) show the analysis results corresponding to the silk shape when the silk addition amount is 0.8 g (mixed weight ratio 4.4%). The amount of 1.0 denier cotton yarn added is 0.08 g (mixing weight ratio 0.44%).
[0133]
[Table 51]

[0134]
The following conclusions can be derived from the above analysis results by silk fiber shape and by mixing weight ratio (addition amount) of silk fibers.
[0135]
First, considering Tables 44 to 48 and FIGS. 26 to 30 for each silk fiber shape, the top of the bar graph of the silk-added methyl methacrylate resin is not added with silk in any silk fiber shape. It is always above the tip of the bar graph of methyl resin. Therefore, it can be seen that the addition of silk clearly contributes to improving the strength of the base material, and the fiber reinforced plastic has high strength.
[0136]
Further, methyl methacrylate resin and polysulfone resin without addition of silk are compared with methyl methacrylate resin with addition of silk fiber, maximum limit value / N at maximum load, bending value / mm with respect to bending stress / MPa, Elongation value /% is low. On the other hand, the fiber reinforced plastic to which silk fiber is added increases the bending value / mm and the elongation value /% in proportion to the increase in the maximum limit value / N and bending stress / MPa at the maximum load. For this reason, the addition of silk improves the stress-strain relationship, in other words, the mechanical properties of the base material are improved, and the strength is increased and the stickiness is increased as compared with the case where no silk is added.
[0137]
Moreover, it cannot be said from the above graph that the strength increases in proportion to the increase in the amount of silk fiber added. Table 52 shows the strength ranking according to the amount of added silk extracted from Table 44 to Table 48 for each silk fiber shape. The strength ranking in Table 52 is determined by data of bending stress / MPa.
[0138]
[Table 52]

[0139]
In Table 52, the silk fiber mixing weight ratio of 4.4% exhibited a relatively high strength in each silk shape of the 27, 29, and 32 denier twisted yarns, but was not the first in the strength ranking. Similarly, with a 32 denier twisted yarn, a silk mixing weight ratio of 15% exhibited high strength, but was not ranked first in the strength ranking. In addition, the fastening yarn is 0.22% in the silk mixing weight ratio, and the 29 and 32 denier twisted yarns are 2.2% in the silk mixing weight ratio and the strength rank is first. Considering the results of Example 1 (when the base material is methyl methacrylate resin) and the like, it can be determined that the strength of the fiber reinforced plastic also depends on the shape of the silk fiber added to the base material. The silk fiber to be considered is considered to have an optimum shape from the viewpoint of strength, an optimum mixing weight ratio range according to the shape, and the like.
[0140]
Here, a theoretical consideration is made on the experimental results.
[0141]
Judging from the test results, when trying to improve the strength of the base material by adding the silk fiber such as methyl methacrylate resin as the base material, rather than simply depending on the mixing weight ratio of the silk fiber, the strength improves. It seems that the strength is improved by the influence of the volume ratio of the silk fiber added to the base material, the ratio of the silk fiber to the base material particles, the cross-sectional area ratio of the silk fiber itself at the molecular level, and the like. And since silk has affinity with the polymeric plastic material whose base material is sericin surrounding the surface of the fiber bundle, the mixed silk exhibits a cross-linking action to improve the strength of the base material, or the silk fiber It is thought that the strength of the base material is improved by the strengthening action of the bundle of structures itself. Therefore, it seems to be important for the silk fiber to be added, such as a shape for binding the methyl methacrylate resin that is in a polymer state in a chain, and by such synergistic action of the crosslinking action and reinforcing action, It is thought to be a fiber reinforced plastic with dramatically increased strength.
[0142]
Further, as described above, from the viewpoint of improving the strength and the like, it is considered that there are more desirable shapes of added silk fibers, their mixing weight ratio, and the like. For example, judging from the above Examples 1 to 4, the shape and thickness of the added silk fiber is preferably 2 twisted 27 denier twisted yarn, 4 twisted 29 denier twisted yarn, 6 twisted 32 denier twisted yarn, etc. About 2.2% to 15% is desirable. This is because the silk fibroin fiber itself has a structure that is easy to blend with the polymer and has an appropriate strength, and the fibroin fiber bundle is twisted and has a thin and irregular cross-section, making it easy to cross the matrix material. In addition to improving the strength, the base material molecules can be easily taken into the gaps from which sericin has been removed by refining, thereby improving the strength of the base material. For the above reasons, by adjusting the refining degree of the silk fiber, when high strength is required, the strength is improved by using the highly refined silk fiber, and the pharmacological effect by sericin etc. such as denture base When expected, it is possible to exert a pharmacological effect using silk fibers having a relatively low refining degree, and the fiber-reinforced plastic of the present invention has a variety of uses.
[0143]
Next, the eligibility of the fiber reinforced plastic as a denture base will be described.
[0144]
Table 53 shows the characteristics of methyl methacrylate resin and polysulfone, which are representative materials usable for denture bases.
[0145]
[Table 53]

[0146]
Methyl methacrylate resin and polysulfone resin have the above-mentioned advantages and disadvantages, but neither is an ideal denture base material. Therefore, a denture base is made of a fiber reinforced plastic obtained by adding silk fibers to non-toxic methyl methacrylate resin. The method for producing the denture base is substantially the same as the technique for producing a denture base using methyl methacrylate resin, which is a normal denture base material, except that fiber reinforced plastic is used.
[0147]
When examining the characteristics of the denture base manufactured using the fiber reinforced plastic as a material as described above, (A) Denture base made of fiber reinforced plastic is stronger than denture base of methyl methacrylate resin, (I) The amount of base plastic used for denture base materials can be reduced. (U) Because there is no risk of generating environmental hormones or dioxins, it is safe for the human body, (D) Expected to have positive effects on the human body such as water retention by added silk fiber and medicinal effects by sericin, sericin also has the ability to control blood cholesterol levels benign, (E) It has a positive effect on the environment associated with the production of fiber reinforced plastics. (F) Silk fiber reinforced plastic and its denture base are easy to manufacture and low in cost, and can be easily customized to individual customers. Effectiveness such as positive effects.
[0148]
In addition, when using other fiber reinforced plastics, such as glass fiber reinforced plastics and carbon fiber reinforced plastics, directly on the human body such as a denture base, there are the following problems, unlike silk fiber reinforced plastics. For example, when it is assumed that a reinforced plastic mixed with glass fiber is used as a denture base, the denture base is attached to the human body, so it is very dangerous and harmful to the human body and cannot clear safety standards. That is, when the wear rate of plastic and glass fiber is compared, the wear rate of plastic is larger, so that exposed fibers may get into the oral cavity. In addition, assuming that carbon fiber reinforced plastic is used as a denture base, dentures and denture bases are tailor-made for each individual, but it is difficult to operate with the carbon fiber reinforced plastic denture base. In addition, if a denture base is actually made of carbon fiber reinforced plastic as described above, enormous costs are incurred for mechanical equipment and the like. On the other hand, the silk fiber reinforced plastic according to the present invention and its denture base do not have the above disadvantages. For example, even if the silk fiber is exposed from the denture base, it has a positive effect on the human body. In addition, it has easy operability.
[0149]
Since the fiber-reinforced plastic and its denture base according to the present invention have the above-described configuration, they exhibit good characteristics such as high strength, and have high adaptability to the ecological environment such as the human body and nature, and the preservation of the global environment and the human body. The effect is that health can be maintained. That is, the fiber-reinforced plastic and its denture base have no risk of generating chemical substances harmful to the ecological environment, such as dioxins and environmental hormones (endocrine disrupting chemical substances) generated during incineration, and properties such as strength. High performance can be achieved.
[0150]
Further, since the fiber reinforced plastic and its denture base are molded from a synthetic resin, the processing is easy and has high operability and convenience, and the manufacturing cost is low and the economy is excellent. There is.
[0151]
Furthermore, the fiber reinforced plastic and its denture base have not only an adverse effect on the ecological environment, but also have an effect of positively affecting the human body and the like. That is, sericin forming a silk fiber structure exerts an effective pharmacological action for mucosal diseases and skin diseases. For example, in a denture base used directly on the human body, it includes patients with the above diseases. Thus, the health of the denture base user can be maintained and enhanced, and medical costs can be suppressed and reduced.
[0152]
The fiber reinforced plastic can be widely used for industrial products and the like in consideration of the ecological environment. By producing and spreading the fiber reinforced plastic, an industry that can be called an environmental industry can be established. That is, since silk fibers necessary for the fiber-reinforced plastic are produced, cocoons and sericulture are indispensable, and a wide range of mulberry fields is required. For this reason, fallow fields are used and agriculture is flourishing, and employment in rural areas is expanded. Furthermore, planting mulberry trees increases the greenery, and CO in the atmosphere ₂ Can contribute to the improvement of soil quality as a deciduous tree, and can also be expected to improve the water quality of the surrounding water system.

Claims (2)

  A denture base characterized by being formed by dispersing and adding a predetermined proportion of silk fibers in a methyl methacrylate resin having a predetermined mechanical property and a predetermined biocompatibility.   Weight ratio of two twisted 27 denier twisted yarns, 4 twisted 29 denier twisted yarns, 6 twisted 32 denier twisted yarns in a methyl methacrylate resin having predetermined mechanical properties and predetermined biocompatibility A denture base comprising a fiber plastic formed by dispersion addition of 2.2% to 15%.

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