JP2006022174A - Biodegradable resin composition molding and method for producing the same - Google Patents
Biodegradable resin composition molding and method for producing the same Download PDFInfo
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本発明は、生分解性樹脂組成物成形品、具体的にはポリ乳酸コンパウンド成形品に関するものであり、詳しくは優れた耐熱性を有するとともに、ポリ乳酸の結晶化時間の短縮や様々な化合物の原料にリサイクル可能な生分解性樹脂組成物成形品に関するものである。 The present invention relates to a biodegradable resin composition molded article, specifically, a polylactic acid compound molded article. Specifically, the present invention has excellent heat resistance, shortens the crystallization time of polylactic acid, and various compounds. The present invention relates to a biodegradable resin composition molded product that can be recycled as a raw material.
従来から、軽量で加工性にすぐれ、腐食、分解しにくい特性を利用した各種プラスチック製品の多くが市場に出まわり、安価で、かつその利便性から、人の生活面や各種産業面の隅々にまでゆきわたってきている。一方、このような状況に対応して、使用後の前記プラスチック製品の廃棄物量が年々増加の傾向にあり、そのうえ、腐食、分解しにくい特性の物質であることから、これが大きな公害問題になってきている。
かかる情勢に対処して、上記の腐食、分解しにくいプラスチック製品に代わる、自然界に存在する生物、特に土や水の中の微生物により容易に、そして、最終的に水と二酸化炭素に分解される各種の生分解性樹脂の開発がなされ、環境保全型製品として注目されている。
Conventionally, many plastic products that use light weight, excellent workability, and are difficult to corrode and decompose have been put on the market. They are inexpensive and convenient. It has become even to the day. On the other hand, in response to this situation, the amount of plastic product waste after use tends to increase year by year, and furthermore, it is a substance with properties that are difficult to corrode and decompose, and this has become a major pollution problem. ing.
Coping with this situation, it is easily degraded by natural organisms, especially microorganisms in the soil and water, and finally decomposed into water and carbon dioxide instead of the above-mentioned corrosion and difficult-to-decompose plastic products. Various biodegradable resins have been developed and are attracting attention as environmentally friendly products.
ポリ乳酸は、デンプンを発酵して得られた乳酸から合成される環境への負荷が少ない、バイオベースポリマーである。そして、ポリ乳酸の成形品は、市販のポリ乳酸ペレットを、金型温度３０℃、保持時間２５秒という条件のもとに射出成形して作製されていた。ポリ乳酸の特徴として、高い融点（約１６０℃）が挙げられるが、非結晶状態のボリ乳酸では耐熱性が低い（荷重たわみ温度が５３℃）ため、ポリ乳酸の成形品を結晶化して耐熱性を上げる必要がある。 Polylactic acid is a bio-based polymer with a low environmental load synthesized from lactic acid obtained by fermenting starch. A molded product of polylactic acid was produced by injection molding a commercially available polylactic acid pellet under the conditions of a mold temperature of 30 ° C. and a holding time of 25 seconds. Polylactic acid is characterized by a high melting point (about 160 ° C.), but amorphous poly-lactic acid has low heat resistance (the deflection temperature under load is 53 ° C.). It is necessary to raise.
しかしながら、ポリ乳酸は結晶化速度が遅いため、充分な耐熱性能を発揮する結晶化度（４０％以上）にまで結晶化させるには、１２０℃のオーブン中で１５分程熱処理しなくてはならない。また成形品を熱処理する際、成形品が変形するという問題がある。 However, since polylactic acid has a slow crystallization rate, it must be heat-treated in an oven at 120 ° C. for about 15 minutes in order to crystallize to a degree of crystallinity (40% or higher) that exhibits sufficient heat resistance. . Moreover, when heat-treating a molded product, there is a problem that the molded product is deformed.
この問題を解決するものとして、特許文献１には、ポリ乳酸に結晶核剤としてタルクを２５質量％程配合した結果、ポリ乳酸の結晶化時間が短縮（３０秒）され、射出成形サイクル中に結晶化されることが可能となり、成形品の耐熱性が１００℃以上に改善されたことが開示されている。しかしながら、ポリ乳酸にタルクを２５質量％も添加すると、成形品の比重が増えてしまい、好ましくないという問題が残る。 As a solution to this problem, in Patent Document 1, as a result of blending about 25% by mass of talc as a crystal nucleating agent with polylactic acid, the crystallization time of polylactic acid was shortened (30 seconds), and during the injection molding cycle, It has been disclosed that it is possible to crystallize and the heat resistance of the molded product has been improved to 100 ° C. or higher. However, when 25% by mass of talc is added to polylactic acid, the specific gravity of the molded article increases, which is not preferable.
本発明は、上記のような従来の事情に鑑みてなされたものであり、優れた耐熱性を有するとともに、ポリ乳酸の結晶化時間を短縮すると同時に、そのままで様々な原料にリサイクルできるポリ乳酸コンパウンド成形品およびその製造方法を提供することを目的とする。 The present invention has been made in view of the above-described conventional circumstances, and has a polylactic acid compound that has excellent heat resistance and can be recycled to various raw materials as it is while reducing the crystallization time of polylactic acid. It aims at providing a molded article and its manufacturing method.
本発明は、上記の目的を達成するために下記の構成からなるものである。
（１）ポリ乳酸を主体とする樹脂成分と、結晶核剤として乳酸−糖類共重合樹脂が含まれていることを特徴とするポリ乳酸コンパウンド成形品。
（２）ポリ乳酸成形品中に結晶核剤として、ポリ乳酸１００質量部に対し乳酸−糖類共重合樹脂が１〜２０質量部の範囲で含まれていることを特徴とする前記（１）に記載のポリ乳酸コンパウンド成形品。
（３）乳酸−糖類共重合樹脂が、Ｄ−乳酸−糖類共重合樹脂とＬ−乳酸−糖類共重合樹脂を混合して製造されたものであることを特徴とする前記（１）または（２）に記載のポリ乳酸コンパウンド成形品。
（４）乳酸−糖類共重合樹脂が、Ｄ−乳酸−糖類共重合樹脂とポリＬ−乳酸を混合、またはポリＤ−乳酸とＬ−乳酸−糖類共重合樹脂を混合して製造されたものであることを特徴とする前記（１）〜（３）に記載のポリ乳酸コンパウンド成形品。
（５）乳酸−糖類共重合樹脂の糖類が、多糖類または単糖類であることを特徴とする前記（１）〜（４）に記載のポリ乳酸コンパウンド成形品。
In order to achieve the above object, the present invention comprises the following constitution.
(1) A polylactic acid compound molded article comprising a resin component mainly composed of polylactic acid and a lactic acid-saccharide copolymer resin as a crystal nucleating agent.
(2) In the above (1), the polylactic acid molded article contains a lactic acid-saccharide copolymer resin in a range of 1 to 20 parts by mass with respect to 100 parts by mass of polylactic acid as a crystal nucleating agent. The polylactic acid compound molded article as described.
(3) The lactic acid-saccharide copolymer resin produced by mixing a D-lactic acid-saccharide copolymer resin and an L-lactic acid-saccharide copolymer resin (1) or (2) ).
(4) The lactic acid-saccharide copolymer resin is produced by mixing D-lactic acid-saccharide copolymer resin and poly L-lactic acid, or mixing poly D-lactic acid and L-lactic acid-saccharide copolymer resin. The polylactic acid compound molded article according to any one of (1) to (3) above, wherein
(5) The polylactic acid compound molded article according to any one of (1) to (4) above, wherein the saccharide of the lactic acid-saccharide copolymer resin is a polysaccharide or a monosaccharide.
（６）乳酸−糖類共重合樹脂の平均粒子径が、０．１〜５０μｍであることを特徴とする前記（１）〜（５）に記載のポリ乳酸コンパウンド成形品。
（７）乳酸−糖類共重合樹脂の製造法が、Ｄ−乳酸−糖類共重合樹脂とＬ−乳酸−糖類共重合樹脂を有機溶剤で溶解混合して再沈殿、または二軸押出機で溶融混合して得られることを特徴とする前記（１）〜（６）に記載のポリ乳酸コンパウンド成形品。
（８）Ｄ−乳酸−糖類共重合樹脂およびＬ−乳酸−糖類共重合樹脂の重量平均分子量が、１，０００〜１，０００，０００であることを特徴とする前記（１）〜（７）に記載のポリ乳酸コンパウンド成形品。
（９）ポリ乳酸を主体とする樹脂成分と、結晶核剤として乳酸−糖類共重合樹脂が含まれている成形品の結晶化度が、４０％以上であることを特徴とする前記（１）〜（８）に記載のポリ乳酸コンパウンド成形品。
(6) The polylactic acid compound molded article as described in (1) to (5) above, wherein the lactic acid-saccharide copolymer resin has an average particle size of 0.1 to 50 μm.
(7) A method for producing a lactic acid-saccharide copolymer resin is such that D-lactic acid-saccharide copolymer resin and L-lactic acid-saccharide copolymer resin are dissolved and mixed in an organic solvent and re-precipitated, or melt mixed in a twin screw extruder. The polylactic acid compound molded article according to any one of (1) to (6) above, which is obtained as described above.
(8) The weight average molecular weights of the D-lactic acid-saccharide copolymer resin and the L-lactic acid-saccharide copolymer resin are 1,000 to 1,000,000, (1) to (7) 2. Polylactic acid compound molded article as described in 1.
(9) The degree of crystallinity of a molded product containing a resin component mainly composed of polylactic acid and a lactic acid-saccharide copolymer resin as a crystal nucleating agent is 40% or more (1) The polylactic acid compound molded article as described in (8).
（１０）結晶核剤として、乳酸と糖類と触媒を真空下に加熱、撹拌下に反応させて得たＤ体及びＬ体の乳酸−糖類共重合樹脂ペレットを有機溶剤で溶解混合して再沈殿、または二軸押出機で溶融混合し、次いで共重合樹脂の非溶媒を前記混合液に添加して沈殿物を生成させ、ろ過乾燥した後粉砕して乳酸−糖類共重合樹脂の粉体を生成し、該粉体とポリ乳酸ペレットを二軸押出機中で加熱混合し、次いでペレタイザーでペレット状に切断して生成した乳酸コンパウンドのペレットを射出成形して成形品を作製することを特徴とするポリ乳酸コンパウンド成形品の製造方法。 (10) As a crystal nucleating agent, lactic acid, saccharide and catalyst are heated under vacuum and reacted with stirring to dissolve and mix D-form and L-form lactic acid-saccharide copolymer resin pellets in an organic solvent for reprecipitation. Or melt-mix with a twin-screw extruder, and then add a non-solvent of copolymer resin to the mixture to produce a precipitate, filter dry, and then pulverize to produce a powder of lactic acid-saccharide copolymer resin The powder and polylactic acid pellets are heated and mixed in a twin-screw extruder, then cut into pellets with a pelletizer, and injection molded to produce lactic acid compound pellets to produce a molded product. A method for producing a polylactic acid compound molded article.
すなわち、本発明の骨子は、図１に示した様にＤ−乳酸−糖類共重合樹脂とＬ−乳酸−糖類共重合樹脂を混合し、熱処理することにより得られた高融点乳酸−糖類共重合樹脂を、結晶核剤としてポリ乳酸に配合することにより、ポリ乳酸の結晶化時間を短縮すると同時に成形品の耐熱性（荷重たわみ温度）を１００℃以上に改善するものである。 That is, the gist of the present invention is a high melting point lactic acid-saccharide copolymer obtained by mixing D-lactic acid-saccharide copolymer resin and L-lactic acid-saccharide copolymer resin and heat-treating as shown in FIG. By blending the resin with polylactic acid as a crystal nucleating agent, the crystallization time of polylactic acid is shortened, and at the same time, the heat resistance (deflection temperature under load) of the molded product is improved to 100 ° C. or higher.
本発明に開示する結晶核剤、これを利用した生分解性樹脂組成物成形品およびその製造方法は、タルクを配合した耐熱成形品に較べて以下に列挙する特徴を有する。 The crystal nucleating agent disclosed in the present invention, a biodegradable resin composition molded article using the same, and a method for producing the same have the following characteristics as compared with heat-resistant molded articles containing talc.
（１）タルクの様な無機の結晶核剤とは違い、高融点乳酸−糖類共重合樹脂の比重は１．２８ｇ／ｃｍ３であり、ポリ乳酸の比重（１．２７ｇ／ｃｍ３）とほぼ等しいため、ポリ乳酸中に高融点乳酸−糖類共重合樹脂をいくら配合しても成形品の比重増にはならない。
（２）高融点乳酸−糖類共重合樹脂のポリ乳酸への配合量は、ポリ乳酸１００質量部に対し１０質量部程度で１００℃以上の耐熱性能が得られる。
（３）Ｄ−乳酸−糖類共重合樹脂とＬ−乳酸−糖類共重合樹脂の製造方法は、特開平１０−２０４１５７号公報のなかで開示されているように、無溶媒直接重合法により製造されるため、環境への負荷が少ない。
（４）高融点乳酸−糖類共重合樹脂は、Ｄ−乳酸−糖類共重合樹脂とＬ−乳酸−糖類共重合樹脂を混合して熱処理したものであるため、ポリ乳酸成形品中に高融点乳酸−糖類共重合樹脂が存在するまで、その成形品を加水分解してもＤ−乳酸とＬ−乳酸の混合物になるだけであり、この乳酸は様々な化合物の原料にリサイクルできる。一方、ポリ乳酸中にタルクを配合した成形品から乳酸にリサイクルする場合、成形品を加水分解した後にタルクを除去しなくてはならないため、コストが掛かる。
(1) Unlike inorganic crystal nucleating agents such as talc, the specific gravity of the high melting point lactic acid-saccharide copolymer resin is 1.28 g / cm 3 , which is almost equal to the specific gravity of polylactic acid (1.27 g / cm 3 ). Therefore, no matter how much the high melting point lactic acid-saccharide copolymer resin is added to the polylactic acid, the specific gravity of the molded article does not increase.
(2) The blending amount of the high melting point lactic acid-saccharide copolymer resin into the polylactic acid is about 10 parts by mass with respect to 100 parts by mass of the polylactic acid, and a heat resistance of 100 ° C. or higher is obtained.
(3) The method for producing the D-lactic acid-saccharide copolymer resin and the L-lactic acid-saccharide copolymer resin is produced by a solventless direct polymerization method as disclosed in JP-A-10-204157. Therefore, the load on the environment is small.
(4) The high melting point lactic acid-saccharide copolymer resin is obtained by mixing D-lactic acid-saccharide copolymer resin and L-lactic acid-saccharide copolymer resin and heat-treating them. -Until the saccharide copolymer resin is present, hydrolysis of the molded product only results in a mixture of D-lactic acid and L-lactic acid, and this lactic acid can be recycled to various compound raw materials. On the other hand, when a molded product in which talc is blended in polylactic acid is recycled to lactic acid, talc must be removed after the molded product is hydrolyzed, which is costly.
上記の構成及び特徴を有することにより、本発明においては、優れた耐熱性を有するとともに、ポリ乳酸の結晶化時間が短縮されると同時に、成形品を加水分解したとき様々な化合物の原料にリサイクルできる環境保全型成形品が提供される。 By having the above configuration and characteristics, in the present invention, it has excellent heat resistance and shortens the crystallization time of polylactic acid, and at the same time, when the molded product is hydrolyzed, it is recycled to various compound raw materials. An environmentally friendly molded product is provided.
以下、本発明の構成成分についてさらに詳細に説明する。
本発明のポリ乳酸を主体とする樹脂成分は、市販品ポリ乳酸ペレットをそのまま使用できる。
しかしながら、このポリ乳酸だけを単独で、金型温度３０℃、保持時間２５秒という標準的射出成形条件で成形した成形品は、荷重たわみ温度が５３．０℃と低く、耐熱性が低いため、この成形品を結晶化させて耐熱性を上げなければならないことは、先に記述したとおりである。
Hereinafter, the constituent components of the present invention will be described in more detail.
Commercially available polylactic acid pellets can be used as they are for the resin component mainly composed of polylactic acid of the present invention.
However, since this polylactic acid alone is molded under standard injection molding conditions of a mold temperature of 30 ° C. and a holding time of 25 seconds, the deflection temperature under load is as low as 53.0 ° C. and heat resistance is low. As described above, the molded product must be crystallized to improve heat resistance.
この結晶化速度を促進するために、本発明においては、結晶核剤として乳酸−糖類共重合樹脂を使用する。
ここで、乳酸−糖類共重合樹脂としては、高融点乳酸−糖類共重合樹脂であることが望ましい。融点としては、２００℃以上の高融点であることが望ましい。このような高融点の結晶核剤を使用することにより、耐熱性が向上するとともに、結晶化時間の短縮も可能となる。
In order to accelerate this crystallization rate, in the present invention, a lactic acid-saccharide copolymer resin is used as a crystal nucleating agent.
Here, the lactic acid-saccharide copolymer resin is preferably a high melting point lactic acid-saccharide copolymer resin. The melting point is preferably a high melting point of 200 ° C. or higher. By using such a high melting point crystal nucleating agent, the heat resistance is improved and the crystallization time can be shortened.
また、結晶核剤としての乳酸−糖類共重合樹脂がポリ乳酸コンパウンド成形品中に、ポリ乳酸１００質量部に対し１〜２０質量部の割合で含有されていることが好ましい。
乳酸−糖類共重合樹脂の使用割合を１質量部以上にすることにより結晶化時間を短縮できる。また、共重合樹脂の使用割合を２０質量部以下にすることにより、添加量による耐熱性向上効果を最適化でき、２０質量部以上添加しても耐熱性向上効果は余り向上しなく、不経済になるだけである。
Moreover, it is preferable that the lactic acid-saccharide copolymer resin as a crystal nucleating agent is contained in the polylactic acid compound molded article in a ratio of 1 to 20 parts by mass with respect to 100 parts by mass of polylactic acid.
The crystallization time can be shortened by setting the use ratio of the lactic acid-saccharide copolymer resin to 1 part by mass or more. Moreover, the heat resistance improvement effect by addition amount can be optimized by making the usage-amount of a copolymer resin 20 mass parts or less, and even if it adds 20 mass parts or more, the heat resistance improvement effect does not improve so much and is uneconomical. It only becomes.
乳酸−糖類共重合樹脂は、Ｄ−乳酸−糖類共重合樹脂とＬ−乳酸−糖類共重合樹脂を混合して製造したものであること、およびＤ−乳酸−糖類共重合樹脂とポリＬ−乳酸を混合、またはポリＤ−乳酸とＬ−乳酸−糖類共重合樹脂を混合して製造したものであることが好ましく、また上記の混合割合は上記それぞれの両者の質量比１：１であることが望ましい。これらの乳酸−糖類共重合樹脂は、三者いずれであろうともポリ乳酸コンパウンド成形品においては、同等の効果を奏することは実験的に確認している。 The lactic acid-saccharide copolymer resin is produced by mixing D-lactic acid-saccharide copolymer resin and L-lactic acid-saccharide copolymer resin, and D-lactic acid-saccharide copolymer resin and poly L-lactic acid. Or a mixture of poly-D-lactic acid and L-lactic acid-saccharide copolymer resin, and the mixing ratio is preferably a mass ratio of the above two. desirable. It has been experimentally confirmed that these lactic acid-saccharide copolymer resins have the same effect in a polylactic acid compound molded product regardless of the three.
また、乳酸−糖類共重合樹脂の糖類は、多糖類または単糖類のいずれもが好ましく、多糖類としてはデンプン、セルロース、グリコーゲンなどが代表的なものであり、単糖類としてはブドウ糖、果糖、ガラクトースが例示される。 The saccharide of the lactic acid-saccharide copolymer resin is preferably either a polysaccharide or a monosaccharide. Examples of the polysaccharide include starch, cellulose, glycogen and the like, and examples of the monosaccharide include glucose, fructose, and galactose. Is exemplified.
乳酸−糖類共重合樹脂の平均粒子径は、０．１〜５０μｍであることが好ましい。平均粒子径が０．１μｍ未満であると、分散不良や二次凝集を生じて結晶核剤としての効果が十分に得られなくなり、一方平均的粒子径が５０μｍを越えると、成形した際に成形体の物性に悪影響を与える。 The average particle size of the lactic acid-saccharide copolymer resin is preferably 0.1 to 50 μm. If the average particle size is less than 0.1 μm, poor dispersion or secondary aggregation will occur, and the effect as a crystal nucleating agent will not be sufficiently obtained. On the other hand, if the average particle size exceeds 50 μm, molding will occur. Adversely affects the physical properties of the body.
Ｄ−乳酸−糖類共重合樹脂およびＬ−乳酸−糖類共重合樹脂の重量平均分子量は、１，０００〜１，０００，０００であることが好ましい。
重量平均分子量が１，０００以上の乳酸−糖類共重合樹脂を成形用ポリ乳酸コンパウンド中に混合することによって、コンパウンドの耐熱性および機械的強度がさらに向上する。また重量平均分子量を１，０００，０００以下にすることによって、溶融粘度の過度の上昇が抑制され、各種原料の均一な分散が達成される。
It is preferable that the weight average molecular weights of D-lactic acid-saccharide copolymer resin and L-lactic acid-saccharide copolymer resin are 1,000-1,000,000.
By mixing a lactic acid-saccharide copolymer resin having a weight average molecular weight of 1,000 or more in a molding polylactic acid compound, the heat resistance and mechanical strength of the compound are further improved. Moreover, by making a weight average molecular weight into 1,000,000 or less, the excessive raise of melt viscosity is suppressed and uniform dispersion | distribution of various raw materials is achieved.
ポリ乳酸を主体とする樹脂成分と、結晶核剤として乳酸−糖類共重合樹脂が含まれている成形品の結晶化度が４０％以上であることが好ましく、このように結晶化度を４０％以上にすることによって成形品の耐熱性が十分に高くなる。 It is preferable that the degree of crystallinity of a molded article containing a resin component mainly composed of polylactic acid and a lactic acid-saccharide copolymer resin as a crystal nucleating agent is 40% or more. By setting it as the above, the heat resistance of a molded article becomes high enough.
次に、本発明の成形品の製造方法について説明する。
先ず、ポリ乳酸コンパウンド成形品の製造方法の全般について概略説明を行い、続いて各製造工程について個別に詳細に説明する。
高融点の乳酸−糖類共重合樹脂は、Ｄ−乳酸−糖類共重合樹脂とＬ−乳酸−糖類共重合樹脂を有機溶剤で溶解混合して再沈殿、または二軸押出機で溶融混合して製造する。前者の方法では粉体として得られ、前記したように適度の平均粒子径を持たせることにより、分散不良や成形品の物性に悪影響を及ぼさないようにすることができる。後者の方法ではペレットとして得られ、市販のポリ乳酸ペレットと混練するには、混練効果が一軸スクリュ押出機よりも格段に増加した二軸押出機を使用する必要がある。
Next, the manufacturing method of the molded product of this invention is demonstrated.
First, a general description of the overall method for producing a polylactic acid compound molded article will be given, and then each production process will be explained in detail individually.
A high melting point lactic acid-saccharide copolymer resin is produced by dissolving and mixing D-lactic acid-saccharide copolymer resin and L-lactic acid-saccharide copolymer resin in an organic solvent and re-precipitation, or melt-mixing with a twin screw extruder. To do. In the former method, it is obtained as a powder, and by giving an appropriate average particle diameter as described above, it is possible to prevent adverse effects on the dispersion failure and the physical properties of the molded product. In the latter method, it is obtained as pellets, and in order to knead with commercially available polylactic acid pellets, it is necessary to use a twin screw extruder whose kneading effect is significantly increased as compared with a single screw extruder.
上記のようにして得た高融点乳酸−糖類共重合樹脂を、市販のポリ乳酸ペレット１００質量部に対し１０質量部前後添加して、混練効果の優れた二軸押出機で混練、押出し、次いでペレタイザーでペレット状に切断し、こうして得られたポリ乳酸コンパウンドのペレットを金型を用いる射出成形、圧縮成形、ブロー成形等により所望の成形品に成形して使用に供する。 The high melting point lactic acid-saccharide copolymer resin obtained as described above is added to around 10 parts by mass with respect to 100 parts by mass of commercially available polylactic acid pellets, and is then kneaded and extruded with a twin screw extruder having an excellent kneading effect. The pellets of the polylactic acid compound thus obtained are cut into pellets with a pelletizer, and formed into a desired molded product by injection molding using a mold, compression molding, blow molding or the like, and used.
そして、先に記述したように、Ｄ−乳酸−糖類共重合樹脂およびＬ−乳酸−糖類共重合樹脂の製造方法は、特開平１０−２０４１５７号公報に開示されているが、このときに使用する反応触媒としては、有機スズ化合物、例えばモノアルキルスズ誘導体、ジアルキルスズ誘導体、具体的にはモノブチルスズオキサイド、１，３−置換−１，１，３，３−テトラオルガノジスタノキサン等が挙げられ、中でも活性の高さから、モノブチルスズオキサイドが好ましい。 As described above, the method for producing the D-lactic acid-saccharide copolymer resin and the L-lactic acid-saccharide copolymer resin is disclosed in Japanese Patent Application Laid-Open No. 10-204157, and is used at this time. Examples of the reaction catalyst include organic tin compounds such as monoalkyltin derivatives and dialkyltin derivatives, specifically monobutyltin oxide, 1,3-substituted-1,1,3,3-tetraorganodistanoxane and the like. Of these, monobutyltin oxide is preferred because of its high activity.
以下に、各製造工程を個別に説明する。
・高融点乳酸−糖類共重合樹脂の製造
（１）Ｄ−乳酸−糖類共重合樹脂の合成
還流塔を設置した容量９０リットルのリアクターに、３０ｋｇの９０％Ｄ−乳酸とコーンスターチ０．１質量部（３０ｇ）、そして触媒としてモノブチルスズオキサイド０．０５質量部（１５ｇ）を投入し、真空度を１３Ｐａに保ちながら１９５℃に加熱撹拌した。この時の撹拌翼の回転数は１２０ｒｐｍであり、反応時間は２２時間である。こうして得られた樹脂は、ゲルパーミェーションクロマトグラフィー（ＧＰＣ）で分子量を測定した結果、重量平均分子量は９６，０００であった。また融点を示差走査熱量計（ＤＳＣ）で測定した結果、１５３．０℃であった。
Below, each manufacturing process is demonstrated separately.
-Production of high melting point lactic acid-saccharide copolymer resin (1) Synthesis of D-lactic acid-saccharide copolymer resin 30 kg of 90% D-lactic acid and 0.1 parts by mass of corn starch in a reactor having a capacity of 90 liters equipped with a reflux tower (30 g) and 0.05 part by mass (15 g) of monobutyltin oxide as a catalyst were added, and the mixture was heated and stirred at 195 ° C. while maintaining the degree of vacuum at 13 Pa. The rotation speed of the stirring blade at this time is 120 rpm, and the reaction time is 22 hours. As a result of measuring the molecular weight of the resin thus obtained by gel permeation chromatography (GPC), the weight average molecular weight was 96,000. Moreover, it was 153.0 degreeC as a result of measuring melting | fusing point with a differential scanning calorimeter (DSC).
（２）Ｌ−乳酸−糖類共重合樹脂の合成
還流塔を設置した容量９０リットルのリアクターに、３０ｋｇの９０％Ｌ−乳酸とコーンスターチ０．１質量部（３０ｇ）、そして触媒としてモノブチルスズオキサイド０．０５質量部（１５ｇ）を投入し、真空度を１３Ｐａに保ちながら１９５℃に加熱撹拌した。この時の撹拌翼の回転数は１２０ｒｐｍであり、反応時間は２２時間である。こうして得られた樹脂は、ＧＰＣで分子量を測定した結果、重量平均分子量は８１，０００であった。融点は１５５．２℃であった。
(2) Synthesis of L-lactic acid-saccharide copolymer resin In a reactor having a capacity of 90 liters equipped with a reflux tower, 30 kg of 90% L-lactic acid, 0.1 part by mass of corn starch (30 g), and monobutyltin oxide 0 as a catalyst .05 parts by mass (15 g) was added, and the mixture was heated and stirred at 195 ° C. while maintaining the degree of vacuum at 13 Pa. The rotation speed of the stirring blade at this time is 120 rpm, and the reaction time is 22 hours. The resin thus obtained was measured for molecular weight by GPC, and as a result, the weight average molecular weight was 81,000. The melting point was 155.2 ° C.
（３）高融点乳酸−糖類共重合樹脂の製造
上記の（１）と（２）で得られた、Ｄ−乳酸−糖類共重合樹脂およびＬ−乳酸−糖類共重合樹脂のペレットを、それぞれ５０ｇづつ５リットル容器に投入し、１．３リットルのクロロホルムで溶解した。ペレットが完全にクロロホルムに溶解したのを確認した後、その溶液にメタノール２．０リットルを加え、溶液中に沈殿物を生じさせた。
溶液をろ過し、沈殿物をバット上に広げ、１１０℃以上に加熱したオーブンで１２時間以上沈殿物を乾燥した。乾燥した沈殿物９６ｇを、乳鉢で粉砕して粉体とし、篩にかけて平均粒子径が１３．４μｍの粉体を得た。得られた粉体の融点をＤＳＣで測定した結果、２０４．４℃であった。
(3) Production of high melting point lactic acid-saccharide copolymer resin 50 g each of the pellets of D-lactic acid-saccharide copolymer resin and L-lactic acid-saccharide copolymer resin obtained in (1) and (2) above. Each was put into a 5 liter container and dissolved in 1.3 liters of chloroform. After confirming that the pellet was completely dissolved in chloroform, 2.0 liters of methanol was added to the solution to cause precipitation in the solution.
The solution was filtered, the precipitate was spread on a vat, and the precipitate was dried in an oven heated to 110 ° C. or more for 12 hours or more. 96 g of the dried precipitate was pulverized in a mortar to form a powder, and sieved to obtain a powder having an average particle size of 13.4 μm. It was 204.4 degreeC as a result of measuring melting | fusing point of the obtained powder by DSC.
以下、本発明を実施例によりさらに詳細に説明するが、本発明はこれらの例に限定されるものではない。
実施例１
・ポリ乳酸コンパウンドの製造
市販のポリ乳酸ペレットに対し、高融点乳酸−糖類共重合樹脂の粉体を１０質量部の割合で二軸押出機中で混合し、ペレタイザーでペレット状に切断した。この時の二軸押出機のシリンダー温度は１９０℃以下であった。
EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these examples.
Example 1
-Manufacture of a polylactic acid compound With respect to the commercially available polylactic acid pellet, the powder of high melting-point lactic acid-saccharide copolymer resin was mixed in the ratio of 10 mass parts in the twin-screw extruder, and it cut | disconnected by the pelletizer with the pelletizer. The cylinder temperature of the twin screw extruder at this time was 190 ° C. or less.
・ポリ乳酸コンパウンド試験片の作製
得られたポリ乳酸コンパウンドのペレットを射出成形し、荷重たわみ温度測定用の試験片（ＪＩＳ Ｋ ７１９１）を作製した。この際金型の温度は、ＤＳＣで測定したポリ乳酸コンパウンドの結晶化温度である１０４℃に保っておく。ポリ乳酸コンパウンドを射出成形する時、樹脂を金型内に射出し終わってから金型を開くまでの保持時間は、１８０秒であった。
-Preparation of polylactic acid compound test piece The obtained polylactic acid compound pellet was injection-molded to prepare a test piece for measuring a deflection temperature under load (JIS K 7191). At this time, the mold temperature is kept at 104 ° C., which is the crystallization temperature of the polylactic acid compound measured by DSC. When the polylactic acid compound was injection molded, the holding time from when the resin was completely injected into the mold until the mold was opened was 180 seconds.
・ポリ乳酸コンパウンド試験片の荷重たわみ温度と結晶化度の測定
得られたポリ乳酸コンパウンドの試験片をオイルバス中に漬け、連続的に０．４５ＭＰａの荷重を試験片に掛け続けながらオイルを加熱した（昇温速度２℃／ｍｉｎ）結果、試験片が０．２７ｍｍ撓んだ温度は１１２．０℃であった。
各試験片の結晶化度は、ＤＳＣで結晶化時の発熱量（△Ｈｃ）と溶融時の吸熱量（△Ｈｍ）を測定し、下記式１に各数値を代入して求めた。得られた結晶化度は４７．５％であった。これらの結果を比較例１との比較を容易にするために、表１にまとめて示す。
・ Measurement of deflection temperature and crystallinity of polylactic acid compound test piece Soak the obtained polylactic acid compound test piece in an oil bath and heat the oil while continuously applying 0.45 MPa load on the test piece. (Temperature increase rate 2 ° C./min), the temperature at which the test piece was bent 0.27 mm was 112.0 ° C.
The degree of crystallinity of each test piece was obtained by measuring the calorific value (ΔHc) during crystallization and the endothermic amount (ΔHm) during melting by DSC, and substituting each numerical value into the following formula 1. The crystallinity obtained was 47.5%. These results are summarized in Table 1 for easy comparison with Comparative Example 1.
結晶化度（％）＝（△Ｈｍ＋△Ｈｃ）／９３×１００ 式１ Crystallinity (%) = (ΔHm + ΔHc) / 93 × 100 Formula 1
参考文献：Ｅ．，Ｗ．Ｆｉｓｃｈｅｒ，ｅｔ ａｌ．，Ｋｏｌｌｏｉｄ−Ｚ．ｕ．Ｚ．ｐｏｌｙｍ．，２５１，９８０，（１９７３） Reference: E.E. , W .; Fischer, et al. , Kolloid-Z. u. Z. polym. 251 980 (1973)
比較例１
・ポリ乳酸試験片の作製および荷重たわみ温度と結晶化度の測定（１）
市販のポリ乳酸ペレットを射出成形し、荷重たわみ温度測定用試験片（ＪＩＳ Ｋ ７１９１）を作製した。
このときの金型温度は３０℃、保持時間は２５秒である。得られた試験片について荷重たわみ試験と結晶化度の測定を行った結果、荷重たわみ温度は５３℃、結晶化度は７．５％であった。
これらの結果も実施例１との比較を容易にするために、上記の表１にまとめて示した。
Comparative Example 1
-Preparation of polylactic acid test piece and measurement of deflection temperature under load and crystallinity (1)
A commercially available polylactic acid pellet was injection molded to prepare a test piece for measuring a deflection temperature under load (JIS K 7191).
The mold temperature at this time is 30 ° C., and the holding time is 25 seconds. The obtained test piece was subjected to a load deflection test and a measurement of crystallinity. As a result, the deflection temperature under load was 53 ° C. and the crystallinity was 7.5%.
These results are also shown in Table 1 above for easy comparison with Example 1.
比較例２
・ポリ乳酸試験片の作製および荷重たわみ温度と結晶化度の測定（２）
実施例１のポリ乳酸コンパウンドの成形条件（金型温度１０４℃、保持時間１８０秒）と同じ条件でポリ乳酸成形品の作製を試みたが、ポリ乳酸は金型内で固まらずにゴム状であったため、試験片の作製は不可能であった。
Comparative Example 2
-Preparation of polylactic acid test piece and measurement of deflection temperature under load and crystallinity (2)
An attempt was made to produce a polylactic acid molded product under the same conditions as the molding conditions of the polylactic acid compound of Example 1 (mold temperature: 104 ° C., holding time: 180 seconds). Therefore, it was impossible to produce a test piece.
以上の結果から、ポリ乳酸に高融点乳酸−糖類共重合樹脂粉末を結晶核剤として添加することによって、結晶化速度が大きくなることが確認され、射出成形サイクル中で結晶化させることが可能となった。また、射出成形サイクル中で結晶化したポリ乳酸コンパウンド試験片の荷重たわみ温度が上昇し、耐熱性が上昇したことがわかった。 From the above results, it was confirmed that by adding a high melting point lactic acid-saccharide copolymer resin powder as a nucleating agent to polylactic acid, the crystallization speed was increased, and it was possible to crystallize in an injection molding cycle. became. It was also found that the deflection temperature under load of the polylactic acid compound test piece crystallized during the injection molding cycle increased and the heat resistance increased.
本発明により製造されたポリ乳酸コンパウンド成形品は、高融点乳酸−糖類共重合樹脂をポリ乳酸中にいくらでも配合でき、１０質量部程度配合すれば１００℃以上の耐熱性（荷重たわみ温度）が得られ、加水分解後は様々な化合物の原料にリサイクルできるので、耐熱性が必要とされる容器、例えば、弁当用トレー、どんぶり、皿、コップなどの食器用途に好適に使用できる他、夏季の倉庫保管中や運搬中においても変形しないため、蓋材や建材、ボード、文具、ケース、キャリアテープ、プリペイドカード、ＩＣカードなどのカード類、ＦＲＰ、各種容器など様々な用途にも適用できる。 The polylactic acid compound molded article produced according to the present invention can contain any amount of high melting point lactic acid-saccharide copolymer resin in polylactic acid, and if it is added in an amount of about 10 parts by mass, heat resistance of 100 ° C. or higher (deflection temperature under load) can be obtained After hydrolysis, it can be recycled into raw materials for various compounds, so it can be used for containers that require heat resistance, such as trays for lunch boxes, bowls, dishes, cups, etc. Since it does not deform during storage or transportation, it can also be applied to various uses such as lids, building materials, boards, stationery, cases, carrier tapes, prepaid cards, IC cards and other cards, FRP, and various containers.
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