JP2005126605A - Heat resistant crosslinked product having biodegradability and method for producing the heat resistant crosslinked product - Google Patents
Heat resistant crosslinked product having biodegradability and method for producing the heat resistant crosslinked product Download PDFInfo
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本発明は生分解性を有する耐熱性架橋物およびその製造方法に関し、フィルム、容器、筐体などの構造体や部品などプラスチック製品が利用される分野において、特に使用後の廃棄処理問題の解決を図るための生分解性製品或いは部品として好適に用いられるものである。 The present invention relates to a heat-resistant crosslinked product having biodegradability and a method for producing the same, and particularly in the field where plastic products such as a structure such as a film, a container, and a casing are used, and a solution for disposal treatment after use. It is suitably used as a biodegradable product or component for the purpose.
現在、多くのフィルムや容器に利用されている石油合成高分子材料は、その原料の枯渇、及び加熱廃棄処理に伴う熱及び排出ガスによる地球温暖化、更に燃焼ガス及び燃焼後残留物中の毒性物質による食物や健康への影響、及び廃棄埋設処理地の確保など、様々な社会的な問題が懸念されている。 Petroleum synthetic polymer materials currently used in many films and containers are depleted of their raw materials, global warming due to heat and exhaust gas from heat treatment, and toxicity in combustion gases and post-combustion residues. There are concerns about various social issues such as the effects of substances on food and health, and securing landfill sites.
これらの問題に対して、デンプンやポリ乳酸を代表とするなどの生分解性高分子は、石油合成高分子の廃棄処理の問題点を解決する材料として従来から注目されてきた材料である。
生分解性高分子は、石油合成高分子に比べて、燃焼に伴う熱量が少なく自然環境での分解再合成のサイクルが保たれる等、生態系を含む地球環境に悪影響を与えない。中でも、強度や加工性の点で、石油合成高分子に匹敵する特性をもつ脂肪族ポリエステル系の樹脂は、近年注目を浴びてきた素材である。特に、ポリ乳酸は、植物から供給されるデンプンから作られ、近年の大量生産によるコストダウンで他の生分解性高分子に比べて非常に安価になりつつある点から、現在その応用について多くの検討がなされている。
In response to these problems, biodegradable polymers such as starch and polylactic acid have been attracting attention as materials for solving the problems of disposal of petroleum synthetic polymers.
Biodegradable polymers do not adversely affect the global environment, including ecosystems, as compared to petroleum synthetic polymers, the amount of heat associated with combustion is small and the cycle of decomposition and resynthesis in the natural environment is maintained. Among them, aliphatic polyester resins having properties comparable to petroleum synthetic polymers in terms of strength and processability are materials that have attracted attention in recent years. In particular, polylactic acid is made from starch supplied from plants, and is currently becoming much cheaper than other biodegradable polymers due to cost reduction due to mass production in recent years. Consideration has been made.
ポリ乳酸は、その特性の面から見ても汎用の石油合成高分子に匹敵する加工性、強度を持つことから、その代替材料にもっとも近い生分解性樹脂である。また、アクリル樹脂に匹敵する透明性からその代替や、ヤング率が高く形状保持性がある点からは電気機器の筐体等のＡＢＳ樹脂の代替等、様々な用途への応用が期待される。 Polylactic acid is a biodegradable resin that is closest to its substitute material because it has processability and strength comparable to general-purpose petroleum synthetic polymers in terms of its characteristics. In addition, it is expected to be applied to various uses such as substitution from transparency comparable to acrylic resin, and substitution of ABS resin such as a casing of electrical equipment from the viewpoint of high Young's modulus and shape retention.
しかしながら、ポリ乳酸は６０℃近辺と比較的低い温度にガラス転移点をもち、その温度前後でいわゆるガラス板が突然ビニル製のテーブルクロスになってしまうというほどに、ヤング率が激減し、もはや低温時の形状を維持することが困難になるという、致命的な欠点を持つ。
かつ、１６０℃と比較的高い融点に達するまでは溶融しないポリ乳酸の結晶部分が、大きな塊状を示さない微結晶であり、通常の結晶化度では結晶部分だけで全体の強度を支えるような構造になりにくいることもこの激しいヤング率変化の一因ではあるが、非結晶の部分が自由に動くようになる温度であるガラス転移点前後でその変化が起こることから、非結晶部分が６０℃以上で殆ど分子間の相互作用を失うことに大きな原因があると言える。
However, polylactic acid has a glass transition point at a relatively low temperature of around 60 ° C., and the so-called glass plate suddenly becomes a vinyl table cloth before and after that temperature. It has a fatal defect that it is difficult to maintain the shape of time.
In addition, the polylactic acid crystal part that does not melt until it reaches a relatively high melting point of 160 ° C. is a microcrystal that does not show a large lump shape, and in a normal crystallinity, the crystal part alone supports the overall strength. Although it is a cause of this drastic change in Young's modulus, the change occurs before and after the glass transition temperature, which is the temperature at which the amorphous part can move freely. Thus, it can be said that there is a major reason for almost losing the interaction between molecules.
高温下での形状保持力が無く、耐熱性の劣る欠点を改善する方法として、非結晶部分を減少させ、ポリ乳酸の結晶化度を９０〜９５％に高めると、６０℃以上における軟化を抑制し、その形状を保持することが可能になる。
しかしながら、ポリ乳酸の結晶化度を高める具体的な方法としては、射出成形などでポリ乳酸を一旦溶融させて様々な形状に成形した後、融点以下ガラス転移温度以上の温度で結晶化が進行していくまで長時間そのまま維持しておく必要がある。よって、例えば、ほんの数ミリから１センチ弱の厚みの部品を作るのに、射出成形後、数十分も加温しつつ金型内で維持する必要があり、工業生産的に利用できず現実的なものではない。
As a method of improving the disadvantages of lack of shape retention at high temperatures and poor heat resistance, reducing the non-crystalline portion and increasing the crystallinity of polylactic acid to 90-95% suppresses softening at 60 ° C or higher. And it becomes possible to hold | maintain the shape.
However, as a specific method for increasing the degree of crystallinity of polylactic acid, after the polylactic acid is once melted and molded into various shapes by injection molding or the like, crystallization proceeds at a temperature below the melting point and above the glass transition temperature. It is necessary to keep it as it is for a long time. Therefore, for example, in order to make a part with a thickness of only a few millimeters to less than 1 cm, it is necessary to maintain it in the mold while heating for several tens of minutes after injection molding. It is n’t.
上記ポリ乳酸の耐熱性を図るために、雑誌「プラスチックエージ」に「高耐熱性ポリ乳酸射出成形グレード アドバンスト・テラマック」（非特許文献１）が発表されている。
上記非特許文献１には、ナノオーダーの微細粒子の鉱物フィラーをポリ乳酸に混ぜ込んで、その粒子を核に比較的短い時間で結晶化度を上げる技術が開示されている。
In order to improve the heat resistance of the polylactic acid, “High Heat-resistant Polylactic Acid Injection Molding Grade Advanced Terramac” (Non-Patent Document 1) has been published in the magazine “Plastic Age”.
Non-Patent Document 1 discloses a technology in which a nano-sized fine particle mineral filler is mixed with polylactic acid and the degree of crystallization is increased in a relatively short time using the particle as a nucleus.
上記論文に記載された方法では、従来の数十分から数分のオーダーで金型から取り出すことが可能であり、現実的な製造が可能となりつつある。しかし、工業生産的なコストの面では改善は見られるものの、不透明な粘土フィラーをポリ乳酸の１〜５重量％以上も混合しているため、元々ポリ乳酸が持つ透明性が失われ、且つ元々ガラスのように光沢感のあるポリ乳酸表面がフィラーによってザラザラした手触りになり、見た目の悪さなどの欠点があり、利用できる製品が限られることとなる。 In the method described in the above paper, it is possible to take out from the mold on the order of several tens of minutes to several minutes, and realistic manufacturing is becoming possible. However, although there is an improvement in terms of industrial production cost, since the opaque clay filler is mixed with 1 to 5% by weight or more of polylactic acid, the transparency inherent in polylactic acid is lost, and originally A glossy polylactic acid surface such as glass has a rough feel due to the filler, and has disadvantages such as poor appearance, and the usable products are limited.
さらに、配合する鉱物フィラーは元の大きさ以上に分散させることは不可能であるため、強度的なバラツキが発生し易く、また、鉱物フィラーとベースの樹脂の間には基本的に結合はなく、補強効果はもっぱらフィラー自身の強度に依存するため、強度を高めるためにはフィラーの配合量を多くする必要があり、フィラー配合量を多くすると上記透明感や平滑性が損なわれる。さらにまた、フィラーを混合成形した場合、フィラーはベースの樹脂から外に出てくるブリード現象が経時的に起こやすい等の問題がある。
本発明は上記問題に鑑みてなされたもので、生分解性材料からなり、ガラス転移点以上で激しく低下する形状保持性を改良して耐熱性を付与し、かつ、透明性、表面光沢感および平滑性を損なわない生分解性を有する耐熱性架橋物および、工業生産上も実用性のある製造方法を提供することを課題としている。 The present invention has been made in view of the above problems, is made of a biodegradable material, improves the shape retention that is drastically lowered above the glass transition point, imparts heat resistance, and has transparency, surface glossiness and It is an object of the present invention to provide a heat-resistant crosslinked product having biodegradability that does not impair smoothness and a production method that is practical in industrial production.
本発明者は、この問題について鋭意研究を重ねた結果、生分解性脂肪族ポリエステルと疎水性多糖類誘導体の両者を架橋により一体化させることで、上記問題を解決できることを見出した。
さらに、上記耐熱性架橋物を製造する方法として、生分解性脂肪族ポリエスエル、疎水性多糖類誘導体、架橋型多官能性モノマーの３種を、該生分解性脂肪族ポリエスエルの融点以上の温度において、均一に混合した後に、該混合物に電離性放射線を照射することを特徴とする製造方法を知見した。
As a result of intensive studies on this problem, the present inventor has found that the above problem can be solved by integrating both the biodegradable aliphatic polyester and the hydrophobic polysaccharide derivative by crosslinking.
Furthermore, as a method for producing the above heat-resistant crosslinked product, three types of biodegradable aliphatic polyester, hydrophobic polysaccharide derivative and cross-linked polyfunctional monomer are used at a temperature equal to or higher than the melting point of the biodegradable aliphatic polyester. The present inventors have found a production method characterized by irradiating the mixture with ionizing radiation after uniform mixing.
上記知見に基づいてなされた第１の発明は、生分解性脂肪族ポリエステルと疎水性多糖類誘導体の両者が架橋により一体化していることを特徴とする耐熱性架橋物を提供している。
上記「一体化」とは、両成分が元来単一では溶解可能な溶媒に、架橋により不溶化した物の成分として、両者の一部が少なくとも含まれることを指す。
The first invention made based on the above knowledge provides a heat-resistant crosslinked product characterized in that both the biodegradable aliphatic polyester and the hydrophobic polysaccharide derivative are integrated by crosslinking.
The term “integrated” means that at least a part of both components is included as a component of a product insolubilized by crosslinking in a solvent in which both components can be originally dissolved.
具体的には、本発明の耐熱性架橋物は、ゲル分率（ゲル分乾燥重量／初期乾燥重量）が５０％〜９５％の架橋構造としている。
ゲル分率の測定は、サンプルシートの所定量を２００メッシュのステンレス金網に包み、クロロホルム溶液の中で４８時間煮沸したのちに、クロロホルムに溶解したゾル分を除いて残ったゲル分を得る。５０℃２４時間で乾燥してゲル中のクロロホルムを除去してゲル分の乾燥重量を測定し、以下の式でゲル分率を計算する。
ゲル分率（％）＝（ゲル分乾燥重量）／（初期乾燥重量）×１００
Specifically, the heat-resistant crosslinked product of the present invention has a crosslinked structure with a gel fraction (gel content dry weight / initial dry weight) of 50% to 95%.
The gel fraction is measured by wrapping a predetermined amount of a sample sheet in a 200-mesh stainless steel wire net and boiling it in a chloroform solution for 48 hours, and then removing the sol dissolved in chloroform to obtain the remaining gel. Dry at 50 ° C. for 24 hours to remove chloroform in the gel, measure the dry weight of the gel, and calculate the gel fraction by the following formula.
Gel fraction (%) = (gel content dry weight) / (initial dry weight) × 100
上記のように、本発明の耐熱性架橋物は、主たる成分は生分解性脂肪族ポリエステルからなるポリマーのゲル分率を５０％以上、望ましくは６５％以上とし、生分解性脂肪族ポリエステルを疎水性多糖類誘導体と架橋して一体化し、ポリマー内に無数の三次元網目構造としているため、ポリマーのガラス転移温度以上でも変形しない耐熱性を付与することができる。よって、生分解性材料の欠点であった耐熱性を改善でき、従来の石油合成高分子からなる汎用樹脂製品と同様の形状保持力を備え、その代替品として利用でき、かつ、生分解性を有するため破棄処理問題を解決することができる。 As described above, the heat resistant cross-linked product of the present invention is such that the main component of the polymer composed of biodegradable aliphatic polyester is 50% or more, preferably 65% or more, and the biodegradable aliphatic polyester is hydrophobic. Since it is crosslinked and integrated with the functional polysaccharide derivative to form an infinite number of three-dimensional network structures in the polymer, heat resistance that does not deform even at a temperature higher than the glass transition temperature of the polymer can be imparted. Therefore, the heat resistance, which was a drawback of biodegradable materials, can be improved, has the same shape retention as conventional resin products made of petroleum synthetic polymers, can be used as an alternative, and has biodegradability. Therefore, the discard processing problem can be solved.
本発明の本来の目的は、様々な特性において汎用石油合成高分子と同等の特性を持ち、それを代替しうる生分解性を有する耐熱性架橋物を提供することにある。したがって、本発明の目的に供される上記生分解性脂肪族ポリエステルとしては、ポリ乳酸、そのＬ体、Ｄ体、または混合物、ポリブチレンサクシネート、ポリカプロラクトン、ポリヒドロキシブチレートなどが上げられるが、コスト面や特性面からは、特にポリ乳酸類が適している。 The original object of the present invention is to provide a heat-resistant cross-linked product having biodegradability that has various properties equivalent to those of general-purpose petroleum synthetic polymers and can be substituted for them. Therefore, examples of the biodegradable aliphatic polyester provided for the purpose of the present invention include polylactic acid, L-form, D-form, or a mixture thereof, polybutylene succinate, polycaprolactone, polyhydroxybutyrate and the like. In view of cost and characteristics, polylactic acids are particularly suitable.
さらに、上記本発明の目的に供される架橋して生分解性脂肪族ポリエステルと一体化させる疎水性多糖類誘導体としては、トウモロコシデンプン、馬鈴薯デンプン、甘藷デンプン、小麦デンプン、米デンプン、タピオカデンプン、サゴデンプンなどのデンプンを原料とする、メチルデンプン、エチルデンプンなどのエーテル化デンプン誘導体、酢酸エステルデンプン、脂肪酸エステルデンプンなどのエステル化デンプン誘導体、及びアルキル化デンプン誘導体が挙げられる。
また、疎水性多糖類誘導体としては、セルロースを原料とするデンプン同様の誘導体、およびプルランなどの他の多糖類の誘導体も利用可能である。
Furthermore, the hydrophobic polysaccharide derivatives that are crosslinked and integrated with the biodegradable aliphatic polyester for the purpose of the present invention include corn starch, potato starch, sweet potato starch, wheat starch, rice starch, tapioca starch, Examples thereof include etherified starch derivatives such as methyl starch and ethyl starch, esterified starch derivatives such as acetate ester starch and fatty acid ester starch, and alkylated starch derivatives based on starch such as sago starch.
As the hydrophobic polysaccharide derivative, derivatives similar to starch using cellulose as a raw material, and derivatives of other polysaccharides such as pullulan can also be used.
上記疎水性多糖類誘導体は単独あるいは２種類以上を混合して利用可能であるが、脂肪族ポリエステルと混合する目的を鑑みれば、基本的に水酸基の置換度が１．５以上、望ましくは１．８以上、さらに望ましくは２．０以上に十分置換された誘導体で、すなわち十分疎水化されているものが好適に利用できる。
上記置換度とは、多糖類が１構成単位にもつ３つの水酸基のうち、エステル化などで置換された水酸基の数の平均値をいい、従って、置換度の最大値は３である。多糖類の誘導体は、その置換導入した官能基にも影響されるが、一般に、置換度１．５以下が親水性、１．５以上が疎水性を示す。
The above hydrophobic polysaccharide derivatives can be used alone or in combination of two or more. However, in view of the purpose of mixing with an aliphatic polyester, the degree of substitution of hydroxyl groups is basically 1.5 or more, preferably 1. Derivatives sufficiently substituted with 8 or more, more desirably 2.0 or more, that is, those sufficiently hydrophobized can be suitably used.
The degree of substitution refers to the average value of the number of hydroxyl groups substituted by esterification or the like among the three hydroxyl groups of the polysaccharide in one constituent unit. Therefore, the maximum value of the degree of substitution is 3. The polysaccharide derivative is affected by the functional group introduced by substitution, but generally has a degree of substitution of 1.5 or less and is hydrophilic, and 1.5 or more is hydrophobic.
さらに、これらへの添加物として、柔軟性を向上させる目的で、グリセリンやエチレングリコール、トリアセチルグリセリンなどの常温では液状の可塑剤、あるいは常温では固形の可塑剤としての、ポリグルコール酸やポリビニルアルコール等の生分解性樹脂の添加、あるいは、例えばポリ乳酸に少量のポリカプロラクトンを添加する可塑剤として添加する等、他の生分解性脂肪酸ポリエステルを添加することは可能であるが、本発明においては必須ではない。 Furthermore, as an additive to these, for the purpose of improving flexibility, polyglycolic acid or polyvinyl alcohol as a liquid plasticizer at room temperature such as glycerin, ethylene glycol or triacetylglycerin, or as a solid plasticizer at room temperature It is possible to add other biodegradable fatty acid polyesters such as the addition of a biodegradable resin such as, for example, as a plasticizer for adding a small amount of polycaprolactone to polylactic acid. Not required.
脂肪族ポリエステルと疎水性多糖類にアリル基を有するモノマーを配合することが好ましい。このモノマーは両者を単独でも架橋することが可能である。
上記脂肪族ポリエステルと疎水性多糖類に一分子内に二つ以上の二重結合を持つアクリル系およびメタクリル系のモノマー、例えば１，６ヘキサンジオールジアクリレート（以下、ＨＤＤＡと記す）、トリメチロールプロパントリメタクリレート（以下、ＴＭＰＴと記す）などでも効果はあるが、比較的低濃度で高い架橋度を得るには、次に挙げるアリル基を有するモノマーが有効である。
It is preferable to add a monomer having an allyl group to the aliphatic polyester and the hydrophobic polysaccharide. This monomer can crosslink both alone.
Acrylic and methacrylic monomers having two or more double bonds in one molecule in the above aliphatic polyester and hydrophobic polysaccharide, such as 1,6 hexanediol diacrylate (hereinafter referred to as HDDA), trimethylolpropane Trimethacrylate (hereinafter referred to as TMPT) is effective, but the following monomers having an allyl group are effective for obtaining a high degree of crosslinking at a relatively low concentration.
トリアリルイソシアヌレート、トリメタアリルイソシアヌレート、トリアリルシアヌレート、トリメタアリルシアヌレート、ジアリルアミン、トリアリルアミン、ジアクリルクロレンテート、アリルアセテート、アリルベンゾエート、アリルジプロピルイソシナヌレート、アリルオクチルオキサレート、アリルプロピルフタレート、ビチルアリルマレート、ジアリルアジペート、ジアリルカーボネート、ジアリルジメチルアンモニウムクロリド、ジアリルフマレート、ジアリルイソフタレート、ジアリルマロネート、ジアリルオキサレート、ジアリルフタレート、ジアリルプロピルイソシアヌレート、ジアリルセバセート、ジアリルサクシネート、ジアリルテレフタレート、ジアリルタトレート、ジメチルアリルフタレート、エチルアリルマレート、メチルアリルフマレート、メチルメタアリルマレート。 Triallyl isocyanurate, trimethallyl isocyanurate, triallyl cyanurate, trimethallyl cyanurate, diallylamine, triallylamine, diacrylic chlorate, allyl acetate, allyl benzoate, allyl dipropyl isocyanurate, allyl octyl oxalate Allylpropyl phthalate, bityl allyl malate, diallyl adipate, diallyl carbonate, diallyl dimethyl ammonium chloride, diallyl fumarate, diallyl isophthalate, diallyl malonate, diallyl oxalate, diallyl phthalate, diallyl propyl isocyanurate, diallyl sebacate, Diallyl succinate, diallyl terephthalate, diallyl tartrate, dimethylallyl phthalate, ethyl allyl Over DOO, methyl allyl fumarate, methyl meta-allyl maleate.
特にその中でも望ましいのは、トリアリルイソシアヌレート（以下、ＴＡＩＣと記す）、トリメタアリルイソシアヌレート（以下ＴＭＡＩＣ）である。また、ＴＡＩＣ、ＴＭＡＩＣと、加熱によって相互に構造変換しうる、トリアリルシアヌレートおよびトリメタアリルシアヌレートも実質的に効果は同様である。 Of these, triallyl isocyanurate (hereinafter referred to as TAIC) and trimethallyl isocyanurate (hereinafter referred to as TMAIC) are particularly desirable. Further, TAIC, TMAIC and triallyl cyanurate and trimethallyl cyanurate, which can be mutually converted by heating, have substantially the same effect.
添加するモノマーの濃度比率は、脂肪酸ポリエステル１００重量％に対して０．１重量％以上で効果が認められ、より効果が確実な濃度は０．５〜３重量％の範囲であるが、生分解性プラスチックとしての使用を勘案すれば、分解が確実な生分解性脂肪族ポリエステルよび疎水性多糖類誘導体を９９％以上とすることが望ましく、従って、上記モノマーは０．５〜１重量％の範囲であることが望ましい。 The concentration ratio of the monomer to be added is 0.1% by weight or more with respect to 100% by weight of the fatty acid polyester, and an effect is confirmed. In view of the use as a functional plastic, it is desirable that the biodegradable aliphatic polyester and the hydrophobic polysaccharide derivative, which are surely decomposed, be 99% or more, and therefore the monomer content is in the range of 0.5 to 1% by weight. It is desirable that
本発明に係わる生分解性を有する耐熱性架橋物は、生分解性脂肪族ポリエステルの融点および疎水性多糖類誘導体の軟化点以上および実質的な溶融成形温度が、１５０℃〜２００℃以下で、該温度近傍の高温時における抗張力が３０〜７０ｇ／ｍｍ2で且つ伸び率が５０〜２０％で、伸びが小さく抗張力が大としている。
上記のように、高温下において、伸び率を小さく抗張力を大とし、変形しにくくしているため、高温時の形状保持力を備え、耐熱性を改善しているため、工業製品として汎用し得るものとなる。
The heat-resistant crosslinked product having biodegradability according to the present invention has a melting point of the biodegradable aliphatic polyester and a softening point of the hydrophobic polysaccharide derivative and a substantial melt molding temperature of 150 ° C to 200 ° C, The tensile strength at a high temperature in the vicinity of the temperature is 30 to 70 g / mm 2 , the elongation is 50 to 20%, the elongation is small, and the tensile strength is large.
As mentioned above, at high temperatures, it has a low elongation and a high tensile strength, making it difficult to deform, so it has shape retention at high temperatures and improved heat resistance, so it can be widely used as an industrial product. It will be a thing.
第２の本発明は、上記本発明の耐熱性架橋物の製造方法として、生分解性脂肪族ポリエスエル、疎水性多糖類誘導体、架橋型多官能性モノマーの３種を、該生分解性脂肪族ポリエスエルの融点点以上の温度において、均一に混合した後に、該混合物に電離性放射線を照射することを特徴とする耐熱性架橋物の製造方法を提供している。 The second aspect of the present invention is a method for producing the heat-resistant crosslinked product of the present invention, wherein three types of biodegradable aliphatic polyester, hydrophobic polysaccharide derivative, and crosslinkable polyfunctional monomer are used as the biodegradable aliphatic. There is provided a method for producing a heat-resistant cross-linked product, characterized in that after mixing uniformly at a temperature equal to or higher than the melting point of polyester, the mixture is irradiated with ionizing radiation.
詳細には、まず、脂肪族ポリエステルおよび疎水性多糖類誘導体の両者が、加熱により溶融または軟化する温度に加熱した状態か、或いはクロロホルムやクレゾール等の両者を溶解しうる溶媒中に溶解・分散した状態とする。次に、そこにモノマーを添加し、これら３つの成分をできるだけ均一に混合する。これら３つの成分は、同時に混合してもよいし、或いはこのうちの２つ、例えば脂肪族ポリエステル中に疎水性多糖類誘導体を十分分散混合させる目的で予め両者のみを混練したもよい。
次に、加熱軟化あるいは溶媒に溶解した状態のまま、あるいは、一旦冷却あるいは溶媒を乾燥除去した後に再び加熱軟化させてプレスし、その後急冷して所望の形状に成形している。
この成形品に対して、架橋反応を生じさせるために電離性放射線を照射している。
Specifically, first, both the aliphatic polyester and the hydrophobic polysaccharide derivative are heated to a temperature at which they are melted or softened by heating, or are dissolved and dispersed in a solvent capable of dissolving both chloroform and cresol. State. The monomer is then added thereto and the three components are mixed as uniformly as possible. These three components may be mixed simultaneously, or only two of them may be kneaded in advance for the purpose of sufficiently dispersing and mixing the hydrophobic polysaccharide derivative in two of them, for example, aliphatic polyester.
Next, it is heated and softened or dissolved in a solvent, or once cooled or dried to remove the solvent, it is heated and softened again, pressed, and then rapidly cooled to form a desired shape.
The molded article is irradiated with ionizing radiation to cause a crosslinking reaction.
照射する電離性放射線としては、γ線、エックス線、β線或いはα線などが使用できるが、工業的生産にはコバルト−６０によるγ線照射や電子加速器による電子線が好ましい。また、架橋反応を発生させるために必要な照射量は１ｋＧｙ以上で３００ｋＧｙ程度まで可能であるが、望ましくは３０〜１００ｋＧｙで、３０〜５０ｋＧｙが最も好ましい。 As the ionizing radiation to be irradiated, γ rays, X-rays, β rays, α rays, or the like can be used. However, for industrial production, γ ray irradiation with cobalt-60 and electron beams with an electron accelerator are preferable. Further, the irradiation dose necessary for generating the crosslinking reaction can be from 1 kGy to 300 kGy, preferably 30 to 100 kGy, and most preferably 30 to 50 kGy.
上記本発明の製造方法では、ＴＡＩＣ等のアリル系モノマーを利用して、電離性放射線を照射して生分解性脂肪酸ポリエステルと疎水性多糖類誘導体とを架橋一体化しているため、脂肪族ポリエステルの欠点である６０℃以上における形状保持性の改良を図るものである。 In the production method of the present invention, an allyl monomer such as TAIC is used to irradiate ionizing radiation to crosslink and integrate the biodegradable fatty acid polyester and the hydrophobic polysaccharide derivative. It is intended to improve the shape retention at 60 ° C. or higher, which is a drawback.
本発明の耐熱性架橋物の主たる成分である生分解性脂肪族ポリエステル、疎水性多糖類誘導体、架橋型多官能性モノマーの関係は以下のように説明できる。
上記３種の混練物に電離性放射線を照射すると、放射線により活性化された架橋型多官能性モノマーによって、主たる成分である生分解性脂肪族ポリエステルの分子同士、混練された疎水性多糖類誘導体の分子同士、さらに生分解性脂肪族ポリエステルと疎水性多糖類誘導体の分子間にも架橋構造が形成され、無数の三次元網目構造となる。
疎水性多糖類誘導体は、一体化する生分解性脂肪族ポリエステルの融点付近で軟化する疎水性多糖類誘導体を選択することで両者の加熱混練ができるが、一般に明確な融点を持たず、高温時でも非常に硬い性質を維持する。ポリ乳酸のように１６０℃付近の融点よりはるかに低い６０℃のガラス転移温度以上の温度で柔らかくなって形状保持性が失われる生分解性脂肪族ポリエステルの場合、１６０℃以上に軟化点を持ち、それ以下の温度では硬く変形しない疎水性多糖類誘導体はその性質で混練物全体に硬い性質を有効に付与する。 即ち、本発明において疎水性多糖類誘導体は、単に生分解性脂肪族ポリエステルに混練されているだけではなく、放射線照射によって活性化された架橋型多官能性モノマーによって、両者が一体化して架橋した網目構造に取り込まれているので、このガラス転移温度以上で硬く容易に形状変形しない耐熱性を、生分解性脂肪族ポリエステルを主たる成分とするポリマー全体に効率よく付与することができる。
The relationship between the biodegradable aliphatic polyester, the hydrophobic polysaccharide derivative, and the crosslinked polyfunctional monomer, which are the main components of the heat-resistant crosslinked product of the present invention, can be explained as follows.
When the above three types of kneaded materials are irradiated with ionizing radiation, the biodegradable aliphatic polyester molecules as the main components are kneaded with the hydrophobic polysaccharide derivative by the cross-linked polyfunctional monomer activated by the radiation. A cross-linked structure is formed between these molecules, and also between the biodegradable aliphatic polyester and the hydrophobic polysaccharide derivative molecules, resulting in an infinite number of three-dimensional network structures.
Hydrophobic polysaccharide derivatives can be heated and kneaded by selecting a hydrophobic polysaccharide derivative that softens near the melting point of the biodegradable aliphatic polyester to be integrated, but generally does not have a clear melting point, But it remains very hard. In the case of biodegradable aliphatic polyesters such as polylactic acid that are softened at a temperature above the glass transition temperature of 60 ° C., which is much lower than the melting point near 160 ° C., and lose their shape retention, they have a softening point above 160 ° C. The hydrophobic polysaccharide derivative that is hard and does not deform at temperatures below that effectively imparts a hard property to the entire kneaded product. That is, in the present invention, the hydrophobic polysaccharide derivative is not only kneaded into the biodegradable aliphatic polyester, but is also cross-linked with the cross-linked polyfunctional monomer activated by radiation irradiation. Since it is incorporated in the network structure, heat resistance that is hard above this glass transition temperature and is not easily deformed can be efficiently imparted to the entire polymer comprising biodegradable aliphatic polyester as a main component.
生分解性脂肪酸ポリエステルに配合する疎水性多糖類誘導体は、高温時に固いという点は、鉱物フィラーを入れて補強する前記非特許文献に開示した方法と似ているが、以下の点で優れている。 The hydrophobic polysaccharide derivative to be blended with the biodegradable fatty acid polyester is similar to the method disclosed in the non-patent document in which a mineral filler is reinforced to be hard at high temperatures, but is excellent in the following points. .
（１）鉱物フィラーは元の大きさ以上に分散させることは不可能であるのに対して、疎水性多糖類誘導体は、加熱や溶媒溶解による混合時に一旦溶融状態になるため、混合具合を任意に選ぶことで混合前の粒子の大きさから分子の大きさまで、脂肪族ポリエステルと任意のレベルで混合させることが可能である。 (1) While it is impossible to disperse the mineral filler beyond its original size, the hydrophobic polysaccharide derivative is once melted when mixed by heating or solvent dissolution, so the mixing condition is arbitrary. It is possible to mix with the aliphatic polyester at an arbitrary level from the particle size before mixing to the molecular size.
（２）鉱物フィラーとベースの樹脂の間には基本的に結合はなく、補強効果はもっぱらフィラー自身の強度に依存するが、疎水性多糖類誘導体は、同じモノマーで架橋するベースの脂肪族ポリエステルとの間にも架橋が起こる。このため、疎水性多糖類誘導体の本来の硬度に、架橋による自身の硬度向上、ベース樹脂との架橋一体化による効果、この３つによって、フィラーとして見た場合の単独の補強効果を上回る耐熱性強度をベースの樹脂に与えることが可能となる。 (2) There is basically no bond between the mineral filler and the base resin, and the reinforcing effect depends solely on the strength of the filler itself, but the hydrophobic polysaccharide derivative is a base aliphatic polyester that is crosslinked with the same monomer. Cross-linking also occurs between the two. For this reason, the original hardness of the hydrophobic polysaccharide derivative is improved by its own hardness by cross-linking, the effect of cross-linking integration with the base resin, and by these three, the heat resistance exceeds the single reinforcing effect when viewed as a filler. Strength can be imparted to the base resin.
（３）フィラーを混合成形した場合、フィラーはベースの樹脂から外に出てくるブリード現象が経時的に起こる問題があるが、前記（２）と同様の理由で、混合時には未架橋で分子がばらばらになって混合しやすいにも関わらず、疎水性多糖類誘導体は放射線照射後には架橋して、誘導体同士或いは脂肪族ポリエステルと架橋一体化して高分子量化するためにブリードすることは全くない。 (3) When filler is mixed and molded, the filler has a problem that the bleed phenomenon that goes out from the base resin occurs with time. For the same reason as in (2) above, the molecules are uncrosslinked during mixing. Despite being separated and easy to mix, the hydrophobic polysaccharide derivative crosslinks after irradiation and does not bleed at all because it is crosslinked and integrated with the derivative or aliphatic polyester to increase the molecular weight.
（４）鉱物フィラーがその混入でたとえばポリ乳酸の透明性や樹脂表面の光沢を失い、さらにざらついた感触を与えるのに対して、本発明では、混合の具合によって多少透明性は失われるものの軽微で、表面の質感も損なわない。 (4) Mineral filler, for example, loses the transparency of polylactic acid and the gloss of the resin surface due to its mixing, and gives a rough texture. In the present invention, although the transparency is somewhat lost depending on the mixing condition, it is slight. The surface texture is not impaired.
（５）加工性においては、結晶化度を高めるための高温維持時間は、ナノサイズの鉱物フィラーを利用する方法では比較的短時間化に成功しているが、本発明では、その時間は全く必要ない。したがって製造時間は大幅に短縮可能である。 (5) In terms of workability, the high temperature maintenance time for increasing the degree of crystallinity has been successfully shortened by a method using a nano-sized mineral filler. unnecessary. Therefore, the manufacturing time can be greatly shortened.
放射線照射の代わりに化学開始剤を用いて橋架け反応を発生させる場合、生分解性脂肪族ポリエステルの融点以上の温度でアリル基を有するモノマーと化学開始剤とを加え、よく混練し、均一に混ぜた後、この混合物からなる成形品を、化学開始剤が熱分解する温度まで上げている。
本発明に使用することができる化学開始剤は、熱分解により過酸化ラジカルを生成する過酸化ジクミル、過酸化プロピオニトリル、過酸化ペンソイル、過酸化ジーｔ−ブチル、過酸化ジアシル、過酸化ベラルゴニル、過酸化ミリストイル、過安息香酸−ｔ−ブチル、２，２’−アゾビスイソブチルニトリルなどの過酸化物触媒又はモノマーの重合を開始する触媒であればいずれでもよい。橋かけ作用は、放射線照射の場合と同様、空気を除いた不活性雰囲気下や真空下で行うのが好ましい。
When using a chemical initiator instead of radiation to generate a crosslinking reaction, add a monomer having an allyl group and a chemical initiator at a temperature equal to or higher than the melting point of the biodegradable aliphatic polyester, knead well, and uniformly After mixing, the molded article made of this mixture is raised to a temperature at which the chemical initiator is thermally decomposed.
Chemical initiators that can be used in the present invention are dicumyl peroxide, propionitrile peroxide, pensoyl peroxide, di-t-butyl peroxide, diacyl peroxide, and verargonyl peroxide that generate peroxide radicals by thermal decomposition. , Peroxide catalyst such as myristoyl peroxide, t-butyl perbenzoate, 2,2′-azobisisobutylnitrile, or any other catalyst that initiates polymerization of monomers. The bridging action is preferably performed in an inert atmosphere or air, excluding air, as in the case of radiation irradiation.
以上に示したように、本発明の耐熱性架橋物は、生分解性脂肪族ポリエステル、特にポリ乳酸の６０℃以上における形状保持性を向上させることができる。また、ポリ乳酸に高温時における強度維持のために配合する疎水性多糖類誘導体を用いているため、鉱物フィラーを用いる場合に生じるポリ乳酸の透明性や表面光沢などを大きく損なうことがない。かつ、工業生産的にも多少設定温度を高めにする必要があるものの、従来の射出成形設備で生産性を低下することなく生産することが可能となる。
また、疎水性多糖類誘導体も生分解性である点から、自然界において生態系に及ぼす影響が極めて少ないことから、大量に製造、廃棄されるプラスチック製品全般の代替材料としての応用が期待される。また、生体への影響がない点から、生体内外に利用される医療用器具への適用にも適した材料となる。
As described above, the heat-resistant crosslinked product of the present invention can improve the shape retention of a biodegradable aliphatic polyester, particularly polylactic acid, at 60 ° C. or higher. Further, since the hydrophobic polysaccharide derivative blended in the polylactic acid for maintaining the strength at high temperature is used, the transparency and surface gloss of the polylactic acid generated when using the mineral filler are not greatly impaired. Moreover, although it is necessary to raise the set temperature to some extent in industrial production, it is possible to produce without lowering the productivity with conventional injection molding equipment.
In addition, since hydrophobic polysaccharide derivatives are also biodegradable, they have little impact on ecosystems in nature, and are expected to be used as alternative materials for plastic products in general that are manufactured and discarded in large quantities. In addition, since it does not affect the living body, it is a material suitable for application to medical instruments used inside and outside the living body.
以下、本発明の実施形態を説明する。
実施形態の耐熱性架橋物は、生分解性脂肪族ポリエステルとしてポリ乳酸を用い、該ポリ乳酸に、疎水性多糖類誘導体として酢酸エステルスターチを用いている。さらに、架橋型多官能性モノマーとしてＴＡＩＣを用い、ポリ乳酸１００重量％に対して０．５〜３重量％を配合した組成物からなる。
上記３種を混合し、該混合物を射出成形でシートを成形し、該シートに電離性放射線を３０〜１００ｋＧｙ照射し、ＴＡＩＣにより架橋を促進させて、ポリ乳酸と酢酸エステルスターチを架橋により一体化している。
Embodiments of the present invention will be described below.
The heat-resistant crosslinked product of the embodiment uses polylactic acid as a biodegradable aliphatic polyester, and uses acetic ester starch as a hydrophobic polysaccharide derivative in the polylactic acid. Furthermore, it consists of the composition which mix | blended 0.5 to 3 weight% with respect to 100 weight% of polylactic acid, using TAIC as a bridge | crosslinking type polyfunctional monomer.
The above three types are mixed, the mixture is formed into a sheet by injection molding, ionizing radiation is irradiated to the sheet at 30 to 100 kGy, crosslinking is promoted by TAIC, and polylactic acid and acetate ester starch are integrated by crosslinking. ing.
上記耐熱性架橋物は、ゲル分率が５０〜９５％の架橋構造で、上記生分解性脂肪族ポリエステルの融点以上、疎水性多糖類誘導体の軟化点以上および実質的な溶融成形温度が１５０℃〜２００℃以下で、該温度近傍の高温時における抗張力が３０〜７０ｇ／ｍｍ2で且つ伸び率が５０〜２０％である。よって、高温環境下で、伸びを小さく抗張力を大として、形状保持力を大としている。 The heat-resistant crosslinked product has a crosslinked structure having a gel fraction of 50 to 95%, has a melting point of the biodegradable aliphatic polyester or higher, a softening point or higher of the hydrophobic polysaccharide derivative, and a substantial melt molding temperature of 150 ° C. The tensile strength is 30 to 70 g / mm 2 and the elongation is 50 to 20% at a high temperature around −200 ° C. or lower. Therefore, in a high temperature environment, the elongation is reduced and the tensile strength is increased, and the shape retention force is increased.
なお、本発明は上記実施形態に限定されず、生分解材の原料の種類、疎水性多糖類誘導体の種類および量、架橋型多官能性モノマー種類および配合量をかえることで、電子線の照射量、該電子線の照射により架橋構造（ゲル分率）を本発明の範囲内で変更しえる。 The present invention is not limited to the above-described embodiment, and the electron beam irradiation can be performed by changing the type of raw material of the biodegradable material, the type and amount of the hydrophobic polysaccharide derivative, the type and amount of the crosslinked polyfunctional monomer. The amount of the crosslinked structure (gel fraction) can be changed within the scope of the present invention by irradiation with the electron beam.
（実施例１）
脂肪族ポリエステルとして、微粉末状のポリ乳酸（三井化学製レイシアＨ−１００Ｊ）を使用した。また、疎水性多糖類誘導体として、酢酸エステルスターチ（日本コーンスターチ製ＣＰ−１）の粉末を使用した。
上記多糖類誘導体は、水酸基の置換度が約２．０で、水には不溶であるがアセトンに溶解し、完全に疎水性である。また、１８０℃以上で軟化するものの明確な融点を持たず、非常にヤング率の高い樹脂である。
(Example 1)
As the aliphatic polyester, finely powdered polylactic acid (Lacia H-100J manufactured by Mitsui Chemicals) was used. Moreover, the powder of acetate ester starch (CP-1 by Nippon Corn Starch) was used as a hydrophobic polysaccharide derivative.
The polysaccharide derivative has a hydroxyl group substitution degree of about 2.0, is insoluble in water but dissolves in acetone, and is completely hydrophobic. Moreover, although it softens at 180 degreeC or more, it does not have clear melting point, but is resin with very high Young's modulus.
ポリ乳酸１００重量％に酢酸エステルスターチを５重量部を予め混合した。この混合物を、略閉鎖型混練機ラボプラストミルにて、１９０℃で融解させ、透明になるまで十分溶融混練した。この混合中に、アリル系モノマーの１種であるＴＡＩＣ（日本化成株式会社製）を、ポリ乳酸と酢酸エステルスターチの合計に対して３重量％添加し、回転数２０ｒｐｍで１０分間良く練って混合した。
その後、この混練物を１９０℃熱プレスにし、ついで１００℃／分で急冷して常温とし、１ｍｍ厚のシートを作製した。このシートを、空気を除いた不活性雰囲気下で電子加速器（加速電圧２ＭｅＶ 電流量１ｍＡ）により電子線を５〜１００ｋＧｙで照射し、得られた放射線架橋物を実施例１とした。
5 parts by weight of acetic ester starch was previously mixed with 100% by weight of polylactic acid. This mixture was melted at 190 ° C. in a substantially closed kneader Laboplast Mill, and sufficiently melt-kneaded until it became transparent. During this mixing, 3% by weight of TAIC (Nippon Kasei Co., Ltd.), which is one of allyl monomers, is added to the total of polylactic acid and acetate ester starch, and kneaded well for 10 minutes at a rotation speed of 20 rpm. did.
Thereafter, this kneaded product was subjected to hot pressing at 190 ° C., and then rapidly cooled at 100 ° C./min to normal temperature to produce a 1 mm thick sheet. This sheet was irradiated with an electron beam at 5 to 100 kGy by an electron accelerator (acceleration voltage 2 MeV, current amount 1 mA) under an inert atmosphere excluding air, and the obtained radiation cross-linked product was taken as Example 1.
（実施例２，３）
脂肪族ポリエステルと疎水性多糖類誘導体に対するＴＡＩＣの割合を、実施例２では１０重量％、実施例３では３０重量％とした。これ以外は実施例１と同様にした。
（実施例４）
実施例４は疎水性多糖類誘導体として置換度約２のセルロースジアセテート（ダイセル株式会社製、酢酸セルロースＬ−３０）を用い、かつ、脂肪族ポリエステルに対する疎水性多糖類誘導体の割合を１０重量％とした。これ以外は実施例２と同様とした。
（実施例５）
実施例５では疎水性多糖類誘導体として、実施例２と同一の置換度約２のセルロースジアセテートを用い、かつ、脂肪族ポリエステルに対する疎水性多糖類誘導体の割合を３０重量％とした。これ以外は実施例３と同様とした。
これ以外は実施例２および３と同様にして、それぞれ実施例４、実施例５とした。
（実施例６）
脂肪族ポリエステルとしてポリブチレンサクシネート（昭和高分子製ビオノーレ＃１０２０）を用い、疎水性多糖類誘導体として脂肪酸エステルスターチ（日本コーンスターチ製ＣＰ−５）を用いた。上記脂肪酸エステルスターチは置換度が約２、脂肪酸の平均炭化水素長約１０である。
実施例３と同様に脂肪族ポリエステルと疎水性多糖類誘導体に対するＴＡＩＣの割合を３重量％とした。
上記脂肪族ポリエステルと疎水性多糖類誘導体とを軟化温度の１５０℃で混練し、かつ、１５０℃でプレスしてシートを得た。
(Examples 2 and 3)
The ratio of TAIC to aliphatic polyester and hydrophobic polysaccharide derivative was 10% by weight in Example 2 and 30% by weight in Example 3. The rest was the same as in Example 1.
Example 4
Example 4 uses cellulose diacetate having a substitution degree of about 2 as a hydrophobic polysaccharide derivative (manufactured by Daicel Corporation, cellulose acetate L-30), and the ratio of the hydrophobic polysaccharide derivative to the aliphatic polyester is 10% by weight. It was. The rest was the same as in Example 2.
(Example 5)
In Example 5, as the hydrophobic polysaccharide derivative, cellulose diacetate having the same substitution degree of about 2 as in Example 2 was used, and the ratio of the hydrophobic polysaccharide derivative to the aliphatic polyester was 30% by weight. Except this, it was the same as Example 3.
Except this, Example 4 and Example 5 were made in the same manner as Example 2 and 3, respectively.
(Example 6)
Polybutylene succinate (Bionor # 1020, Showa High Polymer) was used as the aliphatic polyester, and fatty acid ester starch (CP-5, Nippon Corn Starch) was used as the hydrophobic polysaccharide derivative. The fatty acid ester starch has a degree of substitution of about 2 and an average fatty acid length of about 10 fatty acids.
As in Example 3, the ratio of TAIC to the aliphatic polyester and the hydrophobic polysaccharide derivative was 3% by weight.
The aliphatic polyester and the hydrophobic polysaccharide derivative were kneaded at a softening temperature of 150 ° C. and pressed at 150 ° C. to obtain a sheet.
（比較例１〜６）
電子線照射を行わないこと以外は、実施例１〜６と同様にして、それぞれ比較例１〜６とした。
（比較例７）
疎水性多糖類誘導体およびモノマーを混練せず、ポリ乳酸のみを原料としたこと以外は実施例１と同様にして、比較例７とした。
（比較例８）
疎水性多糖類誘導体だけを使用しなかったものを比較例８とした。
（比較例９）
ＴＡＩＣの代わりにＴＭＰＴを３重量％使用したこと以外は実施例３と同様にした。
（比較例１０）
架橋型多官能性モノマーを使用しなかったこと以外は、実施例６と同様にした。
(Comparative Examples 1-6)
Except not performing electron beam irradiation, it was set as Comparative Examples 1-6 similarly to Examples 1-6, respectively.
(Comparative Example 7)
Comparative Example 7 was made in the same manner as in Example 1 except that only the polylactic acid was used as a raw material without kneading the hydrophobic polysaccharide derivative and the monomer.
(Comparative Example 8)
A comparative example 8 was obtained by using only the hydrophobic polysaccharide derivative.
(Comparative Example 9)
Example 3 was repeated except that 3% by weight of TMPT was used instead of TAIC.
(Comparative Example 10)
The procedure was the same as Example 6 except that no cross-linked multifunctional monomer was used.
以上の実施例１〜６、および比較例１〜１０の違いを表１にまとめた。 The differences between the above Examples 1 to 6 and Comparative Examples 1 to 10 are summarized in Table 1.
表中、○は試験前後で変化無し、△は曲がる等多少の変化が見られたこと、×は完全に倒れて形状を維持できなかったことを示す。 In the table, ○ indicates that there was no change before and after the test, Δ indicates that there was some change such as bending, and × indicates that the shape could not be maintained due to complete collapse.
以上の実施例１〜６および比較例１〜１０について、ガラス転移点以上の温度における耐熱性向上効果を評価するため、８０℃及び１５０℃における形状保持性を評価した。 評価は、各実施例および比較例の電子線照射量５０ｋＧｙのサンプルにて行った。その結果を表１に付せて表記する。 About the above Examples 1-6 and Comparative Examples 1-10, in order to evaluate the heat-resistant improvement effect in the temperature more than a glass transition point, the shape retainability in 80 degreeC and 150 degreeC was evaluated. Evaluation was performed on samples of electron beam irradiation amount of 50 kGy of each example and comparative example. The results are shown in Table 1.
また、照射による分子の架橋程度を評価する目的で、各実施例および比較例のサンプルの照射量とゲル分率の関係を測定した。その結果を図１に示す。
さらに、ガラス転移点以上におけるヤング率の向上効果をみるために、実施例１〜３および比較例７〜８の電子線照射量５０ｋＧｙのサンプルについて、１００℃引張試験における強度伸び曲線を測定し、その結果を図２に示す。
Further, for the purpose of evaluating the degree of cross-linking of molecules by irradiation, the relationship between the irradiation amount and the gel fraction of the samples of each Example and Comparative Example was measured. The result is shown in FIG.
Furthermore, in order to see the improvement effect of the Young's modulus above the glass transition point, the strength elongation curve in a 100 ° C. tensile test was measured for the samples of Examples 1 to 3 and Comparative Examples 7 to 8 with an electron beam irradiation amount of 50 kGy, The result is shown in FIG.
以下に各評価の評価方法は下記の通りである。 The evaluation methods for each evaluation are as follows.
（１）形状保持性評価
各実施例および比較例のシートを、長さ１０センチ幅１センチの長方形状に切り出したものを、幅がシートの厚みと等しい１ミリで、深さが１センチの溝に、サンプルの長辺が上下になるようにほぼ垂直に立てる。これを８０℃の恒温槽に入れて１時間後にサンプルが自立しているかどうかを評価した。評価は８０℃以外に１５０℃でも行った。
(1) Shape retention evaluation Each sheet of each example and comparative example was cut into a rectangular shape having a length of 10 cm and a width of 1 cm, and the width was 1 mm equal to the thickness of the sheet and the depth was 1 cm. Stand in the groove almost vertically so that the long side of the sample is up and down. This was put into a constant temperature bath at 80 ° C. and evaluated whether or not the sample was self-supporting after 1 hour. Evaluation was also performed at 150 ° C. in addition to 80 ° C.
（２）ゲル分率評価
前述したゲル分率測定方法を同一の方法、即ち、各シートの所定量を２００メッシュのステンレス金網に包み、クロロホルム液の中で４８時間煮沸したのちに、クロロホルムに溶解したゾル分を除いて残ったゲル分を得る。５０℃２４時間で乾燥してゲル中のクロロホルムを除去してゲル分の乾燥重量を測定し、以下の式でゲル分率を計算する。
ゲル分率（％）＝（ゲル分乾燥重量）／（初期乾燥重量）×１００
(2) Gel fraction evaluation The gel fraction measurement method described above is the same method, that is, a predetermined amount of each sheet is wrapped in a 200 mesh stainless wire mesh, boiled in chloroform solution for 48 hours, and then dissolved in chloroform. The remaining gel content is obtained by removing the sol content. Dry at 50 ° C. for 24 hours to remove chloroform in the gel, measure the dry weight of the gel, and calculate the gel fraction by the following formula.
Gel fraction (%) = (gel content dry weight) / (initial dry weight) × 100
（３）高温引張試験評価
幅１ｃｍ長さ１０ｃｍの長方形に、サンプルを成型したのちに、１００℃恒温槽内でチャック間２ｃｍ、引張速度１０ｍｍ／分にて引っ張り、破断するまでの伸びと、抗張力を測定した。測定はサンプルが該恒温槽内で同温度に達したあとに行った。
(3) Evaluation of high-temperature tensile test After molding a sample into a rectangle with a width of 1 cm and a length of 10 cm, the sample was pulled in a 100 ° C constant temperature bath at 2 cm between chucks and at a tensile rate of 10 mm / min. Was measured. The measurement was performed after the sample reached the same temperature in the thermostat.
（実施例および比較例の評価結果）
形状保持性については、表１に示したように、ポリ乳酸のガラス転移点である６０℃を越える８０℃においては、実施例１〜６の全部と比較例８〜１０のサンプルは、加熱前後で変化無かったが、比較例１〜７はシートがとけて倒れるなど形状が保持できなかった。 更に、融点付近の１５０℃では、実施例１だけはシートが曲がってしまって形状に変化が見られたが、他の実施例２〜６は良好な形状保持性を示した。
(Evaluation results of Examples and Comparative Examples)
Regarding shape retention, as shown in Table 1, at 80 ° C., which exceeds 60 ° C., which is the glass transition point of polylactic acid, all of Examples 1 to 6 and Comparative Examples 8 to 10 were subjected to before and after heating. However, in Comparative Examples 1 to 7, the shape could not be maintained, for example, the sheet melted and fell down. Furthermore, at 150 ° C. near the melting point, only in Example 1 the sheet was bent and the shape was changed, but the other Examples 2 to 6 showed good shape retention.
ゲル分率については、図１に示すように、実施例１〜６は電子線照射によって架橋が進んで、混合した脂肪族ポリエステル、疎水性多糖類誘導体、架橋型多官能性モノマーが一体化し、ピークは６８〜９５％に達していた。実施例１〜３は照射量が５０ｋＧｙ付近でピークに達し、実施例４、５、６は１００ｋＧｙでピークに達していた。照射量が１００ｋＧｙを越えると、特に電子線分解性であるポリ乳酸を配合した例では逆に分解が始まってゲル分率が低下していく傾向が見られた。
比較例でも、ポリ乳酸とＴＡＩＣを配合した比較例８は実施例同様に架橋した。比較例９はＴＭＰＴが製造時の熱で架橋を起こしてしまい、電子線照射時には架橋機能を失い、照射しても分解していくことが判った。
As for the gel fraction, as shown in FIG. 1, in Examples 1 to 6, crosslinking proceeds by electron beam irradiation, and the mixed aliphatic polyester, hydrophobic polysaccharide derivative, and crosslinked polyfunctional monomer are integrated. The peak reached 68-95%. Examples 1 to 3 reached a peak at an irradiation dose of about 50 kGy, and Examples 4, 5, and 6 reached a peak at 100 kGy. When the irradiation amount exceeded 100 kGy, in particular, in the case of blending polylactic acid having electron beam decomposability, the decomposition started and the gel fraction tended to decrease.
Also in the comparative example, the comparative example 8 which mix | blended polylactic acid and TAIC was bridge | crosslinked similarly to the Example. In Comparative Example 9, it was found that TMPT caused crosslinking by heat during production, lost the crosslinking function when irradiated with an electron beam, and decomposed even when irradiated.
高温時における抗張力と伸びについては、図２に示すように、１００℃の測定条件下において、ポリ乳酸のみの比較例７では抗張力がほとんどなく引っ張ればいくらでも伸びるようになってしまうが、ポリ乳酸にＴＡＩＣをいれて架橋した比較例８は多少抗張力を示すが十分ではなかった。
これに対して、実施例１〜３では抗張力が３０〜７０ｇ／ｍｍ2で、伸び率が２０〜５０％程度で、疎水性多糖類誘導体の配合量が増えるにつれて抗張力が上昇し、と伸びの低下が見られ、即ち、ヤング率が上昇して、形状保持性が上がっていくことが認められた。
Regarding the tensile strength and elongation at high temperatures, as shown in FIG. 2, under the measurement condition of 100 ° C., in Comparative Example 7 using only polylactic acid, there is almost no tensile strength, but it can be extended as much as possible. Comparative Example 8, which was crosslinked with TAIC, showed some tensile strength, but was not sufficient.
On the other hand, in Examples 1 to 3, the tensile strength is 30 to 70 g / mm 2 , the elongation is about 20 to 50%, the tensile strength increases as the blending amount of the hydrophobic polysaccharide derivative increases, and the elongation increases. A decrease was observed, that is, it was observed that the Young's modulus increased and the shape retention increased.
上記実施例と比較例との評価より、ポリ乳酸は６０℃以上ではヤング率が激減し、材質的に極めて柔らかくなってしまうために、形状保持が困難になる。ＴＡＩＣ等のモノマーの添加による架橋で形状保持性は多少上がるが、不充分であることが確認できた。
また、疎水性多糖類誘導体の酢酸エステルスターチや酢酸エステルセルロースは、同様にＴＡＩＣで架橋する上に、ポリ乳酸のガラス転移点以上でも非常に高いヤング率を示す。これらはポリ乳酸の融点付近においても明確な融点を示さずヤング率があまり下がらないことが確認できた。
From the evaluation of the above examples and comparative examples, the polylactic acid has a Young's modulus drastically reduced at 60 ° C. or higher, and the material becomes extremely soft, so that it is difficult to maintain the shape. It was confirmed that the shape retention was slightly increased by crosslinking by addition of a monomer such as TAIC, but it was insufficient.
In addition, the hydrophobic polysaccharide derivatives acetate starch and cellulose acetate cellulose are similarly crosslinked by TAIC and exhibit a very high Young's modulus even above the glass transition point of polylactic acid. These did not show a clear melting point even near the melting point of polylactic acid, and it was confirmed that the Young's modulus did not decrease so much.
Claims (8)
上記疎水性多糖類誘導体として、酢酸エステルスターチ、脂肪酸エステルスターチまたは酢酸エステルセルロース、
上記架橋型多官能性モノマーとして、トリアリルイソシアヌレートやトリメタアリルイソシアヌレート等のアリル基を有するモノマーが用いられている請求項４に記載の生分解性を有する耐熱性架橋物。 As the biodegradable aliphatic polyester, polylactic acid or polybutylene succinate,
As the hydrophobic polysaccharide derivative, acetate ester starch, fatty acid ester starch or acetate cellulose,
The heat-resistant cross-linked product having biodegradability according to claim 4, wherein a monomer having an allyl group such as triallyl isocyanurate or trimethallyl isocyanurate is used as the cross-linked polyfunctional monomer.
上記温度近傍の高温時における抗張力が３０〜７０ｇ／ｍｍ2で且つ伸び率が５０〜２０％で、伸びが小さく抗張力が大きい請求項１乃至請求項５記載の生分解性を有する耐熱性架橋物。 The melting point of the biodegradable aliphatic polyester and the softening point of the hydrophobic polysaccharide derivative and the substantial melt molding temperature are 150 ° C. to 200 ° C.,
6. A heat-resistant crosslinked product having biodegradability according to claim 1, wherein the tensile strength at a high temperature near the above temperature is 30 to 70 g / mm 2 and the elongation is 50 to 20%, and the elongation is small and the tensile strength is large. .
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| US10/569,966 US20060160984A1 (en) | 2003-10-24 | 2004-10-20 | Biodegradable material and process for producing the same |
| KR1020067004311A KR20060135605A (en) | 2003-10-24 | 2004-10-20 | Biodegradable material and process for producing the same |
| DE112004001201T DE112004001201T5 (en) | 2003-10-24 | 2004-10-20 | Biodegradable material and manufacturing process for the same |
| CN200810181267XA CN101423592B (en) | 2003-10-24 | 2004-10-20 | Biodegradable material and process for producing the same |
| PCT/JP2004/015482 WO2005040255A1 (en) | 2003-10-24 | 2004-10-20 | Biodegradable material and process for producing the same |
| TW093132103A TWI336706B (en) | 2003-10-24 | 2004-10-22 | Biodegradable material and process for producing said biodegradable material |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007092031A (en) * | 2005-08-30 | 2007-04-12 | Sumitomo Electric Fine Polymer Inc | Crosslinked material of polylactic acid and method for manufacturing the same |
| WO2007088920A1 (en) * | 2006-02-02 | 2007-08-09 | Sumitomo Electric Fine Polymer, Inc. | Exterior structure member for electronic device, and electronic device having the exterior structure member |
| WO2009001625A1 (en) * | 2007-06-25 | 2008-12-31 | Sumitomo Electric Industries, Ltd. | Resin composition, and method for production of molded article comprising the resin composition |
| JP2014055266A (en) * | 2012-09-13 | 2014-03-27 | Fuji Xerox Co Ltd | Cross-linked polylactic acid, resin composition, and molded article thereof |
| US9074778B2 (en) | 2009-11-04 | 2015-07-07 | Ssw Holding Company, Inc. | Cooking appliance surfaces having spill containment pattern |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007092031A (en) * | 2005-08-30 | 2007-04-12 | Sumitomo Electric Fine Polymer Inc | Crosslinked material of polylactic acid and method for manufacturing the same |
| WO2007088920A1 (en) * | 2006-02-02 | 2007-08-09 | Sumitomo Electric Fine Polymer, Inc. | Exterior structure member for electronic device, and electronic device having the exterior structure member |
| JPWO2007088920A1 (en) * | 2006-02-02 | 2009-06-25 | 住友電工ファインポリマー株式会社 | Exterior member for electronic device, and electronic device provided with the exterior member |
| WO2009001625A1 (en) * | 2007-06-25 | 2008-12-31 | Sumitomo Electric Industries, Ltd. | Resin composition, and method for production of molded article comprising the resin composition |
| US9074778B2 (en) | 2009-11-04 | 2015-07-07 | Ssw Holding Company, Inc. | Cooking appliance surfaces having spill containment pattern |
| JP2014055266A (en) * | 2012-09-13 | 2014-03-27 | Fuji Xerox Co Ltd | Cross-linked polylactic acid, resin composition, and molded article thereof |
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