JP2007169394A - Method for producing polylactic acid resin expanded particle for in-mold expansion molding - Google Patents

Method for producing polylactic acid resin expanded particle for in-mold expansion molding Download PDF

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JP2007169394A
JP2007169394A JP2005367012A JP2005367012A JP2007169394A JP 2007169394 A JP2007169394 A JP 2007169394A JP 2005367012 A JP2005367012 A JP 2005367012A JP 2005367012 A JP2005367012 A JP 2005367012A JP 2007169394 A JP2007169394 A JP 2007169394A
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polylactic acid
acid resin
particles
resin
foamed
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JP4820641B2 (en
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Takaaki Hirai
孝明 平井
Katsunori Nishijima
克典 西嶋
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Sekisui Kasei Co Ltd
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Sekisui Plastics Co Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a polylactic acid expanded particle for in-mold expansion molding by which an in-mold expansion molded product having excellent heat resistance and mechanical strength is obtained. <P>SOLUTION: The method for producing the polylactic acid resin expanded particle for the in-mold expansion molding is carried out as follows. A polylactic acid resin and an acrylic-styrenic compound having an epoxy group are fed to an extruder to produce an extruded foam. The resultant extruded foam is then cut into a particulate form to produce the expanded particle. In the method, the polylactic acid resin contains optical isomers of both the D- and the L-isomers as a constituent monomer component and the content of whichever smaller of the D- or the L-isomer is <5 mol% or only either one of the optical isomer of the D- or L-isomer is contained as the constituent monomer component. The polylactic acid resin expanded particle is regulated so as to provide <30% open-cell ratio and <30% crystallinity. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

本発明は、型内発泡成形によって耐熱性及び機械的強度に優れたポリ乳酸系樹脂発泡成形体を得ることができる型内発泡成形用ポリ乳酸系樹脂発泡粒子の製造方法に関する。   The present invention relates to a method for producing polylactic acid resin foamed particles for in-mold foam molding, which can obtain a polylactic acid resin foam molded article having excellent heat resistance and mechanical strength by in-mold foam molding.

ポリ乳酸系樹脂は、天然に存在する乳酸を重合されて得られた樹脂であり、自然界に存在する微生物によって分解可能な生分解性樹脂であると共に、常温での機械的特性についても優れていることから注目を集めている。   Polylactic acid resin is a resin obtained by polymerizing naturally occurring lactic acid, is a biodegradable resin that can be decomposed by microorganisms existing in nature, and has excellent mechanical properties at room temperature. It attracts attention.

ポリ乳酸系樹脂は、一般に、Ｄ−乳酸及び／又はＬ−乳酸を重合させるか、或いは、Ｌ−ラクチド、Ｄ−ラクチド及びＤＬ−ラクチドからなる群から選ばれた一又は二以上のラクチドを開環重合させることによって製造されている。   The polylactic acid resin generally polymerizes D-lactic acid and / or L-lactic acid, or opens one or more lactides selected from the group consisting of L-lactide, D-lactide and DL-lactide. Manufactured by ring polymerization.

そして、得られるポリ乳酸系樹脂は、該ポリ乳酸系樹脂中に含有されるＤ体成分或いはＬ体成分の含有比率によって物性、特に結晶性が変化し、具体的には、Ｄ体成分或いはＬ体成分のうちの少ない方の光学異性体の割合が多くなるにしたがってポリ乳酸系樹脂の結晶性が低下し、やがて非結晶性となる。   The obtained polylactic acid-based resin changes in physical properties, particularly crystallinity, depending on the content ratio of the D-form component or L-form component contained in the polylactic acid-based resin. As the proportion of the smaller optical isomer of the body components increases, the crystallinity of the polylactic acid resin decreases and eventually becomes amorphous.

又、ポリ乳酸系樹脂発泡粒子を金型内に充填し、水蒸気などの熱媒体によってポリ乳酸系樹脂発泡粒子を加熱して軟化させると共に発泡させ、ポリ乳酸系樹脂発泡粒子の発泡圧によって発泡粒子同士を融着一体化させて所望形状を有するポリ乳酸系樹脂発泡成形体を製造する方法、所謂、型内発泡成形が提案されている。   Also, the polylactic acid resin foam particles are filled in a mold, and the polylactic acid resin foam particles are heated and softened by a heat medium such as water vapor to be foamed, and the foamed particles are expanded by the foaming pressure of the polylactic acid resin foam particles. A method for producing a polylactic acid-based resin foam molded body having a desired shape by fusing them together, so-called in-mold foam molding, has been proposed.

具体的には、特許文献１には、Ｌ体とＤ体のモル比が９５／５〜６０／４０、又は４０／６０〜５／９５であるポリ乳酸にイソシアネート基≧２．０当量／モルのポリイソシアネート化合物を該ポリ乳酸に対して０．５〜５重量％配合し反応させた樹脂組成物を所定条件で熟成させてなる樹脂組成物が提案され、そして、上記樹脂組成物から粒子を製造し、この粒子に発泡剤及び発泡助剤を含浸させ、得られた発泡性粒子を予備発泡させて発泡粒子を製造し、この発泡粒子を金型に充填して発泡させて所望形状を有する成形体を成形することが開示されている。   Specifically, Patent Document 1 discloses that an isocyanate group ≧ 2.0 equivalents / mol in polylactic acid having a molar ratio of L-form to D-form of 95/5 to 60/40, or 40/60 to 5/95. A resin composition obtained by aging under a predetermined condition a resin composition obtained by mixing 0.5 to 5% by weight of the polyisocyanate compound with respect to the polylactic acid and reacting the same is proposed, and particles are formed from the resin composition. Producing foam particles by impregnating the particles with a foaming agent and a foaming auxiliary agent, pre-foaming the resulting foamable particles, filling the mold with foam, and foaming to have a desired shape It is disclosed to form a shaped body.

しかしながら、上記ポリ乳酸系樹脂は、そのＬ体成分又はＤ体成分のうちの少ない方の光学異性体成分のモル比が５モル％以上であり、ポリ乳酸系樹脂は結晶性が低いか或いは非結晶性であって耐熱性に劣り、得られる成形体の耐熱性はせいぜい５０℃程度であって、実用上の使用には問題点があった。   However, the polylactic acid-based resin has a molar ratio of the smaller optical isomer component of the L-form component or the D-form component of 5 mol% or more, and the polylactic acid-based resin has low crystallinity or is not non-crystalline. It is crystalline and inferior in heat resistance, and the resulting molded article has a heat resistance of about 50 ° C. at most, which is problematic for practical use.

そこで、Ｌ体又はＤ体のうちの少ない方の光学異性体のモル比が５モル未満である結晶性の高いポリ乳酸系樹脂を用いることが考えられるが、粒子に発泡剤を含浸させて発泡性粒子とし、この発泡性粒子を加熱して予備発泡させていることから、この発泡過程で加えられる熱によってポリ乳酸系樹脂の結晶化が進行してしまい、結晶化度の高い発泡粒子となり、その結果、得られる発泡粒子の融着性が低下してしまい、このような発泡粒子を用いて得られる成形体は、融着性が悪くて機械的強度が低いといった問題点があった。   Therefore, it is conceivable to use a polylactic acid-based resin with high crystallinity in which the molar ratio of the smaller optical isomer of L-form or D-form is less than 5 moles. Since the foamable particles are heated and pre-foamed, the polylactic acid resin is crystallized by the heat applied in the foaming process, resulting in foamed particles having a high degree of crystallinity. As a result, the fusibility of the foamed particles obtained is lowered, and a molded product obtained using such foamed particles has a problem that the fusibility is poor and the mechanical strength is low.

又、Ｌ体又はＤ体のうちの少ない方の光学異性体のモル比が５モル未満であるか、或いは、Ｌ体又はＤ体のうちの何れか一方の光学異性体のみを含有しているポリ乳酸系樹脂は、その結晶性が高く耐熱性に優れているものの、結晶性が高くなるにしたがって脆性が高くなることから、得られる型内発泡成形体の耐衝撃性が不充分であるといった問題点があった。   Moreover, the molar ratio of the smaller optical isomer of L-form or D-form is less than 5 moles, or contains only one optical isomer of either L-form or D-form. Although the polylactic acid resin has high crystallinity and excellent heat resistance, the brittleness increases as the crystallinity increases, so that the impact resistance of the in-mold foam molded product obtained is insufficient. There was a problem.

更に、特許文献２には、ポリ乳酸系樹脂と、カルボキシル基及び／又は水酸基との反応性を持つ官能基を有する単量体単位を構成単位として含むビニル重合体を含有するポリ乳酸系樹脂組成物であり、２００℃におけるひずみ０．１％、周波数１００ｒａｄ／ｓにおけるせん断粘度が８００〜２０００Ｐａ・ｓであり、かつ、一軸伸長速度１．０ｓｅｃ-1、一軸伸長歪み１．０〜４．０における一軸伸長粘度の歪み硬化度λが０．４〜０．８であることを特徴とするポリ乳酸系樹脂組成物が提案されており、ダイレクトブロー成形体、インフレーション成形体、発泡成形体、押出成形体などの成形に有利なレオロジー特性を有しており、このポリ乳酸系樹脂組成物を用いた成型品を得ることができることが開示されている。 Furthermore, Patent Document 2 discloses a polylactic acid resin composition containing a polylactic acid resin and a vinyl polymer containing a monomer unit having a functional group having reactivity with a carboxyl group and / or a hydroxyl group as constituent units. It has a strain of 0.1% at 200 ° C., a shear viscosity of 800 to 2000 Pa · s at a frequency of 100 rad / s, a uniaxial elongation rate of 1.0 sec −1 , and a uniaxial elongation strain of 1.0 to 4.0. A polylactic acid resin composition characterized in that the strain hardening degree λ of the uniaxial elongation viscosity is 0.4 to 0.8 has been proposed, and a direct blow molded article, an inflation molded article, a foam molded article, an extrusion It has been disclosed that it has rheological properties advantageous for molding of molded articles and the like, and a molded product using this polylactic acid-based resin composition can be obtained.

しかしながら、特許文献２には、ポリ乳酸系樹脂組成物を用いて押出発泡により発泡体を製造することが記載されているものの、型内発泡成形については一切、開示されていない。   However, Patent Document 2 describes that a foam is produced by extrusion foaming using a polylactic acid resin composition, but does not disclose in-mold foam molding at all.

上述したように、型内発泡成形は、ポリ乳酸系樹脂発泡粒子を型内にて発泡させ、このポリ乳酸系樹脂発泡粒子の発泡圧によってポリ乳酸系樹脂発泡粒子同士を融着一体化させるものであって、押出発泡とは異なり、ポリ乳酸系樹脂発泡粒子同士の融着性を考慮する必要がある。   As described above, in-mold foam molding is one in which polylactic acid resin foamed particles are foamed in the mold, and the polylactic acid resin foamed particles are fused and integrated by the foaming pressure of the polylactic acid resin foamed particles. However, unlike extrusion foaming, it is necessary to consider the fusibility between the foamed polylactic acid resin particles.

従って、特許文献２のように、ポリ乳酸系樹脂組成物に発泡剤を含有させて押出発泡体を製造することはできても、得られた押出発泡体を粒子状に切断して発泡粒子とし、この発泡粒子を型内発泡成形に用いようとしても、発泡粒子同士の融着性に欠け、良好なポリ乳酸系樹脂発泡体を得ることができなかった。   Therefore, as disclosed in Patent Document 2, even though an extruded foam can be produced by adding a foaming agent to the polylactic acid resin composition, the obtained extruded foam is cut into particles to form expanded particles. Even if the foamed particles were used for in-mold foam molding, the foamed particles lacked the fusibility, and a good polylactic acid resin foam could not be obtained.

特開２０００−１７０３７号公報JP 2000-17037 A 特開２００５−２３９９３２号公報JP 2005-239932 A

本発明は、型内発泡成形によって耐熱性及び機械的強度に優れたポリ乳酸系樹脂発泡成形体を得ることができる型内発泡成形用ポリ乳酸系樹脂発泡粒子の製造方法を提供する。   The present invention provides a method for producing polylactic acid resin foamed particles for in-mold foam molding, which can obtain a polylactic acid resin foam molded article having excellent heat resistance and mechanical strength by in-mold foam molding.

本発明の型内発泡成形用ポリ乳酸系樹脂発泡粒子の製造方法は、ポリ乳酸系樹脂と、エポキシ基を有するアクリル・スチレン系化合物とを押出機に供給して発泡剤の存在下にて溶融混練し押出発泡して押出発泡体を製造し、この押出発泡体を粒子状に切断して発泡粒子を製造するポリ乳酸系樹脂発泡粒子の製造方法において、上記ポリ乳酸系樹脂が、その構成モノマー成分としてＤ体及びＬ体の双方の光学異性体を含有し且つＤ体又はＬ体のうちの少ない方の光学異性体の含有量が５モル％未満であるか、或いは、構成モノマー成分としてＤ体又はＬ体のうちの何れか一方の光学異性体のみを含有していると共に、ポリ乳酸系樹脂発泡粒子の連続気泡率が３０％未満で且つポリ乳酸系樹脂発泡粒子の結晶化度が３０％未満となるように調整することを特徴とする。以下の説明において、「型内発泡成形用ポリ乳酸系樹脂発泡粒子」を単に「ポリ乳酸系樹脂発泡粒子」と表現する。   The method for producing foamed polylactic acid resin particles for in-mold foam molding of the present invention is to supply a polylactic acid resin and an acrylic / styrene compound having an epoxy group to an extruder and melt in the presence of a foaming agent. In the method for producing a polylactic acid resin foamed particle, which is kneaded and extruded and foamed to produce an extruded foam, and the extruded foam is cut into particles to produce foamed particles. The component contains both optical isomers of D-form and L-form, and the content of the optical isomer of the lesser of D-form and L-form is less than 5 mol%, or D as a constituent monomer component Only the optical isomer of either the L-form or the L-form, the open cell ratio of the polylactic acid-based resin expanded particles is less than 30%, and the crystallinity of the polylactic acid-based resin expanded particles is 30 Adjust to be less than% I am characterized in. In the following description, “polylactic acid resin foamed particles for in-mold foam molding” is simply expressed as “polylactic acid resin foamed particles”.

本発明で用いられるポリ乳酸系樹脂は、一般に市販されているポリ乳酸系樹脂を用いることができ、具体的には、ポリ乳酸系樹脂は下記化１で示され、Ｄ−乳酸及びＬ−乳酸をモノマーとして共重合させるか、Ｄ−乳酸又はＬ−乳酸の何れか一方をモノマーとして重合させるか、或いは、Ｄ−ラクチド、Ｌ−ラクチド及びＤＬ−ラクチドからなる群より選ばれた一又は二以上のラクチドを開環重合させることによって得ることができ、何れのポリ乳酸系樹脂であってもよい。   As the polylactic acid resin used in the present invention, a commercially available polylactic acid resin can be used. Specifically, the polylactic acid resin is represented by the following chemical formula 1, and D-lactic acid and L-lactic acid. One or more selected from the group consisting of D-lactide, L-lactide and DL-lactide, or D-lactic acid or L-lactic acid as a monomer. Any of the polylactic acid resins may be used.

Figure 2007169394
Figure 2007169394

そして、ポリ乳酸系樹脂を製造するに際して、モノマーとしてＤ体とＬ体とを併用した場合においてＤ体若しくはＬ体のうちの少ない方の光学異性体の割合が５モル％未満である場合、又は、モノマーとしてＤ体若しくはＬ体のうちの何れか一方の光学異性体のみを用いた場合、即ち、上記ポリ乳酸系樹脂が、その構成モノマー成分としてＤ体及びＬ体の双方の光学異性体を含有し且つＤ体又はＬ体のうちの少ない方の光学異性体の含有量が５モル％未満であるか、或いは、構成モノマー成分としてＤ体又はＬ体のうちの何れか一方の光学異性体のみを含有している場合は、得られるポリ乳酸系樹脂は、その結晶性が高くなる一方、モノマーとしてＤ体とＬ体とを併用した場合においてＤ体又はＬ体のうちの少ない方の割合が５モル％以上である時は、少ない方の光学異性体が増加するにしたがって、得られるポリ乳酸系樹脂は、その結晶性が低くなり、やがて非結晶となる。   And when producing a polylactic acid-based resin, when the D isomer and L isomer are used in combination as a monomer, the proportion of the lesser optical isomer of the D isomer or L isomer is less than 5 mol%, or In the case where only one of the optical isomers of D-form or L-form is used as a monomer, that is, the polylactic acid-based resin has both D-form and L-form optical isomers as its constituent monomer components. And the content of the smaller optical isomer of D-form or L-form is less than 5 mol%, or any one of the D-form or L-form optical isomer as a constituent monomer component In the case where only the D-form and the L-form are used together, the polylactic acid-based resin obtained has a higher crystallinity, while the D-form and the L-form are used in combination as a monomer. Is more than 5 mol% When that is, according to the optical isomer is increased the smaller the resulting polylactic acid-based resin, its crystallinity decreases, the eventually amorphous.

従って、本発明では、構成モノマー成分としてＤ体及びＬ体の双方の光学異性体を含有し且つＤ体又はＬ体のうちの少ない方の光学異性体の含有量が５モル％未満であるポリ乳酸系樹脂か、或いは、構成モノマー成分としてＤ体又はＬ体のうちの何れか一方の光学異性体のみを含有しているポリ乳酸系樹脂を用いることによって、得られるポリ乳酸系樹脂発泡粒子の耐熱性を高いものとしている。   Therefore, in the present invention, a polymorphism containing both D-form and L-form optical isomers as a constituent monomer component and the content of the smaller of the D-form and L-form is less than 5 mol%. Polylactic acid resin expanded particles obtained by using a lactic acid resin or a polylactic acid resin containing only one optical isomer of D-form or L-form as a constituent monomer component High heat resistance.

更に、Ｄ体とＬ体をモノマーとして併用して重合させて得られたポリ乳酸系樹脂としては、Ｄ体又はＬ体のうちの何れか少ない方の光学異性体の割合が４モル％未満であるモノマーを重合させて得られたポリ乳酸系樹脂が好ましく、Ｄ体又はＬ体のうちの何れか少ない方の光学異性体の割合が３モル％未満であるモノマーを重合させて得られたポリ乳酸系樹脂がより好ましく、Ｄ体又はＬ体のうちの何れか少ない方の光学異性体の割合が２モル％未満であるモノマーを重合させて得られたポリ乳酸系樹脂が特に好ましい。   Furthermore, the polylactic acid-based resin obtained by polymerizing the D-form and the L-form in combination as a monomer has a ratio of the lesser of the D-form and the L-form of less than 4 mol% of the optical isomer. A polylactic acid resin obtained by polymerizing a certain monomer is preferred, and a polylactic acid resin obtained by polymerizing a monomer in which the proportion of the optical isomer, whichever is smaller, of D-form or L-form is less than 3 mol% A lactic acid-based resin is more preferable, and a polylactic acid-based resin obtained by polymerizing a monomer in which the ratio of the optical isomer, which is the smaller of either the D-form or the L-form, is less than 2 mol% is particularly preferred.

即ち、構成モノマー成分としてＤ体及びＬ体の双方の光学異性体を含有し且つＤ体又はＬ体のうちの少ない方の光学異性体の含有量が４モル％未満であるポリ乳酸系樹脂が好ましく、構成モノマー成分としてＤ体及びＬ体の双方の光学異性体を含有し且つＤ体又はＬ体のうちの少ない方の光学異性体の含有量が３モル％未満であるポリ乳酸系樹脂がより好ましく、構成モノマー成分としてＤ体及びＬ体の双方の光学異性体を含有し且つＤ体又はＬ体のうちの少ない方の光学異性体の含有量が２モル％未満であるポリ乳酸系樹脂が更に好ましい。   That is, a polylactic acid-based resin containing both optical isomers of D-form and L-form as a constituent monomer component, and the content of the smaller optical isomer of D-form or L-form is less than 4 mol%. Preferably, a polylactic acid-based resin that contains both D-form and L-form optical isomers as a constituent monomer component, and the content of the smaller of the D-form and L-form is less than 3 mol%. More preferably, a polylactic acid resin containing both D isomer and L isomer as constituent monomer components, and the content of the lesser of the D isomer and L isomer being less than 2 mol% Is more preferable.

そして、構成モノマー成分としてＤ体及びＬ体を含有するポリ乳酸系樹脂は、Ｄ体又はＬ体のうちの何れか少ない方の光学異性体の割合が少なくなればなる程、ポリ乳酸系樹脂は、その結晶性のみならず融点も上昇する。よって、発泡粒子を金型内に充填して発泡させて得られる発泡成形体の耐熱性も向上し、発泡成形体は高い温度であってもその形態を維持することができ、発泡成形体を金型から高い温度のまま取り出すことが可能となって発泡成形体の金型内における冷却時間が短縮され、発泡成形体の生産効率を向上させることもできる。   And as for the polylactic acid-type resin which contains D body and L body as a constituent monomer component, the ratio of the optical isomer of the smaller one of D body or L body decreases, and the polylactic acid resin becomes In addition to its crystallinity, the melting point increases. Therefore, the heat resistance of the foamed molded product obtained by filling the foamed particles in the mold and foaming is improved, and the foamed molded product can maintain its form even at a high temperature. It becomes possible to take out from the mold at a high temperature, the cooling time in the mold of the foamed molded product is shortened, and the production efficiency of the foamed molded product can be improved.

ここで、ポリ乳酸系樹脂中におけるＤ体又はＬ体の含有量は以下の方法によって測定することができる。先ず、ポリ乳酸系樹脂をクロロホルムに溶解させて、ポリ乳酸系樹脂の濃度が１０ｍｇ／ミリリットルのクロロホルム溶液を作製する。次に、旋光計を用いて２５℃にて波長５８９ｎｍの偏光をクロロホルム溶液に照射して、クロロホルム溶液の比旋光度を測定する。   Here, the content of D-form or L-form in the polylactic acid-based resin can be measured by the following method. First, a polylactic acid resin is dissolved in chloroform to prepare a chloroform solution having a polylactic acid resin concentration of 10 mg / ml. Next, the chloroform solution is irradiated with polarized light having a wavelength of 589 nm at 25 ° C. using a polarimeter, and the specific rotation of the chloroform solution is measured.

一方、モノマーとしてＤ体のみを用いて重合して得られたポリ乳酸系樹脂、或いは、モノマーとしてＬ体のみを用いて重合して得られたポリ乳酸系樹脂について、上述と同様の要領で比旋光度を測定してもよいが、この比旋光度は、通常、既に測定されており、Ｄ体のみを用いて重合して得られたポリ乳酸系樹脂は＋１５６°、モノマーとしてＬ体のみを用いて重合して得られたポリ乳酸系樹脂は−１５６°とされている。   On the other hand, the polylactic acid resin obtained by polymerization using only the D isomer as the monomer, or the polylactic acid resin obtained by polymerizing using only the L isomer as the monomer, was compared in the same manner as described above. Although the optical rotation may be measured, this specific optical rotation is usually already measured. The polylactic acid resin obtained by polymerization using only D-form is + 156 °, and only L-form is used as a monomer. The polylactic acid-based resin obtained by polymerization using it is set to −156 °.

そして、下記式に基づいてポリ乳酸系樹脂中におけるＤ体成分又はＬ体成分の量を算出することができる。
Ｄ体成分量（モル％）＝１００×｛クロロホルム溶液の比旋光度−（−１５６）｝
／｛１５６−（−１５６）｝
Ｌ体成分量（モル％）＝１００−（Ｄ体成分量） And the quantity of D body component or L body component in polylactic acid-type resin is computable based on a following formula.
D-form component amount (mol%) = 100 × {specific rotation of chloroform solution − (− 156)}
/ {156-(-156)}
L-form component amount (mol%) = 100- (D-form component amount)

そして、本発明の型内発泡成形用ポリ乳酸系樹脂発泡粒子の製造方法では、上述のように、一般に市販されているポリ乳酸系樹脂を用いることができるが、このポリ乳酸系樹脂は、動的粘弾性のバランスが悪く、型内発泡成形に適したポリ乳酸系樹脂発泡粒子を得ることが困難である。   In the method for producing foamed polylactic acid resin particles for in-mold foam molding of the present invention, as described above, commercially available polylactic acid resins can be used. The balance of mechanical viscoelasticity is poor, and it is difficult to obtain polylactic acid resin foamed particles suitable for in-mold foam molding.

そこで、本発明では、ポリ乳酸系樹脂の動的粘弾性を調整して押出発泡に適したものとし型内発泡成形に適したポリ乳酸系樹脂発泡粒子を得るべく、押出機にポリ乳酸系樹脂と共に改質剤として、エポキシ基を有するアクリル・スチレン系化合物を供給する。このエポキシ基を有するアクリル・スチレン系化合物は、エポキシ基がポリ乳酸系樹脂の末端基と結合することによってポリ乳酸系樹脂の動的粘弾性を改質する。   Therefore, in the present invention, in order to obtain polylactic acid resin foamed particles suitable for extrusion foaming by adjusting the dynamic viscoelasticity of the polylactic acid resin to obtain polylactic acid resin foam particles suitable for in-mold foam molding, At the same time, an acrylic / styrene compound having an epoxy group is supplied as a modifier. This acrylic / styrene compound having an epoxy group modifies the dynamic viscoelasticity of the polylactic acid resin by bonding the epoxy group to the terminal group of the polylactic acid resin.

更に、ポリ乳酸系樹脂は、その構成モノマー成分としてＤ体又はＬ体のうちの何れか少ない方の光学異性体の割合が０モル％に近づくにしたがって結晶性が高くなり耐熱性が向上する一方、脆性が大きくなるが、上記エポキシ基を有するアクリル・スチレン系化合物は、ポリ乳酸系樹脂の動的粘弾性を改質することによって押出発泡特性の向上のみならず、ポリ乳酸系樹脂の脆性を改善することができ、この改質されたポリ乳酸系樹脂からなるポリ乳酸系樹脂発泡粒子を用いて型内発泡成形により得られるポリ乳酸系樹脂発泡成形体は優れた耐衝撃性を有する。   Furthermore, the polylactic acid-based resin has higher crystallinity and improved heat resistance as the proportion of the optical isomer, which is the lesser of D-form or L-form, as a constituent monomer component approaches 0 mol%. However, the acryl / styrene compound having the epoxy group improves not only the extrusion foaming property by modifying the dynamic viscoelasticity of the polylactic acid resin but also the brittleness of the polylactic acid resin. The polylactic acid-based resin foam molded article obtained by in-mold foam molding using the polylactic acid-based resin foamed particles made of the modified polylactic acid-based resin has excellent impact resistance.

上記エポキシ基を有するアクリル・スチレン系化合物としては、構成モノマー成分として、エポキシ基を有するアクリル系単量体と、スチレン系単量体とを含有してなるビニル重合体が好ましい。   The acrylic / styrene compound having an epoxy group is preferably a vinyl polymer containing an acrylic monomer having an epoxy group and a styrene monomer as constituent monomer components.

そして、上記エポキシ基を有するアクリル系単量体としては、例えば、グリシジルメタアクリレート、グリシジルアクリレート、（３，４−エポキシシクロヘキシル）メチルメタアクリレート、（３，４−エポキシシクロヘキシル）メチルアクリレートなどが挙げられる。又、スチレン系単量体としては、例えば、スチレン、α−メチルスチレン、ｔ−ブチルスチレン、クロルスチレンなどが挙げられる。   Examples of the acrylic monomer having an epoxy group include glycidyl methacrylate, glycidyl acrylate, (3,4-epoxycyclohexyl) methyl methacrylate, and (3,4-epoxycyclohexyl) methyl acrylate. . Examples of the styrene monomer include styrene, α-methylstyrene, t-butylstyrene, chlorostyrene, and the like.

更に、エポキシ基を有するアクリル・スチレン系化合物は、エポキシ基を有するアクリル系単量体及びスチレン系単量体以外の単量体を構成モノマー成分として含有していてもよく、このような単量体としては、例えば、メチルアクリレート、エチルアクリレート、プロピルアクリレート、ブチルアクリレート、２−エチルヘキシルアクリレート、シクロヘキシルアクリレート、メチルメタアクリレート、エチルメタアクリレート、プロピルメタアクリレート、ブチルメタアクリレート、２−エチルヘキシルメタアクリレート、シクロヘキシルメタアクリレートなどが挙げられる。   Further, the acrylic / styrene compound having an epoxy group may contain a monomer other than an acrylic monomer having an epoxy group and a styrene monomer as a constituent monomer component. Examples of the body include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate. An acrylate etc. are mentioned.

なお、エポキシ基を有するアクリル・スチレン系化合物は、例えば、東亜合成社から商品名「ＡＲＵＦＯＮ ＵＧ−４０００」「ＡＲＵＦＯＮ ＵＧ−４０１０」「「ＡＲＵＦＯＮ ＵＧ−４０３０」「ＡＲＵＦＯＮ ＵＧ−４０４０」「ＡＲＵＦＯＮ ＵＧ−４０７０」で市販されている。   Acrylic / styrene-based compounds having an epoxy group are commercially available from Toa Gosei Co., Ltd. under the trade names “ARUFON UG-4000”, “ARUFON UG-4010”, “ARUFON UG-4030”, “ARUFON UG-4040”, “ARUFON UG-”, for example. 4070 ".

そして、押出機に供給するエポキシ基を有するアクリル・スチレン系化合物の量としては、少ないと、ポリ乳酸系樹脂の動的粘弾性の改質効果が低く、得られるポリ乳酸系樹脂発泡粒子の発泡性が低下し且つ連続気泡率が高くなり、ポリ乳酸系樹脂発泡粒子を用いて型内発泡成形を行う際に、ポリ乳酸系樹脂発泡粒子同士の融着性が低下することがある一方、多いと、得られるポリ乳酸系樹脂発泡粒子の結晶性が高くなって、型内発泡成形時のポリ乳酸系樹脂発泡粒子同士の融着性が低下することがあるので、ポリ乳酸系樹脂１００重量部に対して０．１〜２重量部が好ましく、０．２〜１．５重量部がより好ましく、０．３〜１．０重量部が特に好ましい。   If the amount of the acrylic / styrene compound having an epoxy group supplied to the extruder is small, the effect of modifying the dynamic viscoelasticity of the polylactic acid resin is low, and the foamed polylactic acid resin foamed particles are obtained. When the in-mold foam molding is performed using the polylactic acid resin foamed particles, the fusion property between the polylactic acid resin foamed particles may be decreased. And the crystallinity of the obtained polylactic acid-based resin expanded particles may be increased, and the fusion property between the polylactic acid-based resin expanded particles during in-mold foam molding may be reduced. The amount is preferably 0.1 to 2 parts by weight, more preferably 0.2 to 1.5 parts by weight, and particularly preferably 0.3 to 1.0 parts by weight.

更に、エポキシ基を有するアクリル・スチレン系化合物によって改質されたポリ乳酸系樹脂（以下、単に「改質されたポリ乳酸系樹脂」ということがある）、即ち、得られたポリ乳酸系樹脂発泡粒子を構成しているポリ乳酸系樹脂において、ポリ乳酸系樹脂の融点（ｍｐ）と、動的粘弾性測定にて得られた、貯蔵弾性率曲線と損失弾性率曲線との交点における温度Ｔとが後述する式１を満たすように、エポキシ基を有するアクリル・スチレン系化合物の押出機への供給量を調整することが好ましい。   Furthermore, a polylactic acid resin modified with an acrylic / styrene compound having an epoxy group (hereinafter, simply referred to as “modified polylactic acid resin”), that is, the obtained polylactic acid resin foam In the polylactic acid resin constituting the particles, the melting point (mp) of the polylactic acid resin and the temperature T at the intersection of the storage elastic modulus curve and the loss elastic modulus curve obtained by dynamic viscoelasticity measurement However, it is preferable to adjust the supply amount to the extruder of the acryl-styrene type compound which has an epoxy group so that Formula 1 mentioned later may be satisfy | filled.

ここで、動的粘弾性測定にて得られた貯蔵弾性率は、粘弾性において弾性的な性質を示す指標であって、発泡過程における気泡膜の弾性の大小を示す指標であり、発泡過程において、気泡膜の収縮力に抗して気泡を膨張させるのに必要な発泡圧の大小を示す指標である。   Here, the storage elastic modulus obtained by the dynamic viscoelasticity measurement is an index indicating elastic properties in the viscoelasticity, and is an index indicating the elasticity of the bubble film in the foaming process. This is an index indicating the magnitude of the foaming pressure required to expand the bubbles against the contraction force of the bubble film.

即ち、改質されたポリ乳酸系樹脂の動的粘弾性測定にて得られた貯蔵弾性率が低いと、気泡膜が伸長された場合、気泡膜が伸長力に抗して収縮しようとする力が小さく、ポリ乳酸系樹脂発泡粒子の製造に必要とする発泡圧によって発泡膜が容易に伸長してしまう結果、気泡膜が過度に伸長してしまい破泡を生じる一方、改質されたポリ乳酸系樹脂の動的粘弾性測定にて得られた貯蔵弾性率が高いと、気泡膜に伸長力が加わった場合、伸長に抗する気泡膜の収縮力が大きく、ポリ乳酸系樹脂発泡粒子の製造に必要とする発泡圧で一旦、気泡が膨張したとしても、温度低下などに起因する経時的な発泡圧の低下に伴って気泡が収縮してしまう。   That is, if the storage elastic modulus obtained by the dynamic viscoelasticity measurement of the modified polylactic acid resin is low, when the cell membrane is stretched, the force that the cell membrane attempts to contract against the stretching force The foamed film easily stretches due to the foaming pressure required for the production of polylactic acid resin foamed particles, resulting in excessive expansion of the foamed film and foam breakage. On the other hand, modified polylactic acid When the storage elastic modulus obtained by the dynamic viscoelasticity measurement of the resin is high, when the expansion force is applied to the cell membrane, the cell membrane has a large contraction force against the expansion, and the production of polylactic acid resin expanded particles Even if the bubbles expand once at the required foaming pressure, the bubbles contract as the foaming pressure decreases over time due to a temperature drop or the like.

又、動的粘弾性測定にて得られた損失弾性率は、粘弾性において粘性的な性質を示す指標であって、発泡過程における気泡膜の粘性を示す指標であり、発泡過程において、気泡膜をどの程度まで破れることなく伸長させることができるかの許容範囲を示す指標であると同時に、発泡圧によって所望大きさに気泡を膨張させた後、この膨張した気泡をその大きさに維持する能力を示す指標でもある。   Further, the loss modulus obtained by dynamic viscoelasticity measurement is an index indicating a viscous property in viscoelasticity, and is an index indicating the viscosity of the bubble film in the foaming process. This is an index indicating the allowable range of how much can be expanded without breaking, and at the same time, the ability to expand the bubbles to the desired size by the foaming pressure and then maintain the expanded bubbles at that size It is also an indicator that indicates.

即ち、改質されたポリ乳酸系樹脂の動的粘弾性測定にて得られた損失弾性率が低いと、ポリ乳酸系樹脂発泡粒子の製造に必要とする発泡圧によって気泡膜が伸長された場合、気泡膜が容易に破れてしまう一方、改質されたポリ乳酸系樹脂の動的粘弾性測定にて得られた損失弾性率が高いと、発泡力が気泡膜によって熱エネルギーに変換されてしまい、ポリ乳酸系樹脂発泡粒子の製造時に気泡膜を円滑に伸長させることが難しくなり、気泡を膨張させることが困難になる。   That is, when the loss elastic modulus obtained by the dynamic viscoelasticity measurement of the modified polylactic acid resin is low, the cell membrane is stretched by the foaming pressure required for producing the polylactic acid resin expanded particles. While the bubble film is easily broken, if the loss elastic modulus obtained by the dynamic viscoelasticity measurement of the modified polylactic acid resin is high, the foaming force is converted into thermal energy by the bubble film. In the production of the polylactic acid-based resin expanded particles, it becomes difficult to smoothly extend the cell membrane, and it is difficult to expand the cells.

このように、ポリ乳酸系樹脂を発泡させてポリ乳酸系樹脂発泡粒子を製造するにあたっては、発泡過程において、ポリ乳酸系樹脂は、ポリ乳酸系樹脂発泡粒子を得るために必要とされる発泡圧によって気泡膜が破れることなく適度に伸長するための弾性力、即ち、貯蔵弾性率を有している必要があると共に、上記発泡圧によって気泡膜が破れることなく円滑に伸長し、所望大きさに膨張した気泡をその大きさに発泡圧の経時的な減少にかかわらず維持しておくための粘性力、即ち、損失弾性率を有していることが好ましい。   As described above, in producing polylactic acid resin foamed particles by foaming polylactic acid resin, in the foaming process, the polylactic acid resin has a foaming pressure required to obtain polylactic acid resin foamed particles. It is necessary to have an elastic force for stretching the bubble film appropriately without breaking, i.e., a storage elastic modulus, and the bubble film can be smoothly stretched without breaking by the foaming pressure, to a desired size. It is preferable to have a viscous force, that is, a loss elastic modulus, for maintaining the expanded bubble in its size regardless of the decrease in the foaming pressure over time.

つまり、押出発泡工程において、エポキシ基を有するアクリル・スチレン系化合物によって改質されたポリ乳酸系樹脂の貯蔵弾性率及び損失弾性率の双方が押出発泡に適した値を有していることが好ましく、このような押出発泡に適した貯蔵弾性率及び損失弾性率を押出発泡工程においてポリ乳酸系樹脂に付与するために、改質されたポリ乳酸系樹脂における動的粘弾性測定にて得られた、貯蔵弾性率曲線と損失弾性率曲線との交点における温度Ｔ（以下「貯蔵弾性率曲線と損失弾性率曲線との交点における温度Ｔ」ということがある）と、改質されたポリ乳酸系樹脂の融点（ｍｐ）とが、好ましくは下記式１を満たすように、より好ましくは式２を満たすように、特に好ましくは式３を満たすように調整することによって、改質されたポリ乳酸系樹脂の貯蔵弾性率及び損失弾性率をそれらのバランスをとりながら押出発泡に適したものとしてポリ乳酸系樹脂の押出発泡性を良好なものとし、ポリ乳酸系樹脂発泡粒子を安定的に製造することができる。   That is, in the extrusion foaming process, it is preferable that both the storage elastic modulus and the loss elastic modulus of the polylactic acid resin modified by the acrylic / styrene compound having an epoxy group have values suitable for extrusion foaming. In order to impart a storage elastic modulus and loss elastic modulus suitable for such extrusion foaming to the polylactic acid resin in the extrusion foaming process, it was obtained by dynamic viscoelasticity measurement in the modified polylactic acid resin. , A temperature T at the intersection of the storage modulus curve and the loss modulus curve (hereinafter sometimes referred to as “temperature T at the intersection of the storage modulus curve and the loss modulus curve”), and a modified polylactic acid resin By adjusting the melting point (mp) of the polymer so that it preferably satisfies the following formula 1, more preferably satisfies the formula 2, and particularly preferably satisfies the formula 3. Stable production of polylactic acid resin foamed particles with good extrusion foamability of polylactic acid resin by making the storage elastic modulus and loss elastic modulus of acid resin suitable for extrusion foaming while balancing them can do.

〔改質されたポリ乳酸系樹脂の融点（ｍｐ）−４０℃〕
≦交点における温度Ｔ≦改質されたポリ乳酸系樹脂の融点（ｍｐ）・・・式１ [Melting point of modified polylactic acid resin (mp) −40 ° C.]
≦ Temperature at the intersection T ≦ Melting point of modified polylactic acid resin (mp) Equation 1

〔改質されたポリ乳酸系樹脂の融点（ｍｐ）−３８℃〕
≦交点における温度Ｔ≦〔改質されたポリ乳酸系樹脂の融点（ｍｐ）−１０℃〕
・・・式２ [Melting point of modified polylactic acid resin (mp) -38 ° C.]
≦ Temperature at intersection T ≦ [Melting point of modified polylactic acid resin (mp) −10 ° C.]
... Formula 2

〔改質されたポリ乳酸系樹脂の融点（ｍｐ）−３５℃〕
≦交点における温度Ｔ≦〔改質されたポリ乳酸系樹脂の融点（ｍｐ）−２０℃〕
・・・式３ [Melting point of modified polylactic acid resin (mp) -35 ° C.]
≦ Temperature at intersection T ≦ [Melting point of modified polylactic acid resin (mp) −20 ° C.]
... Formula 3

更に、改質されたポリ乳酸系樹脂の動的粘弾性測定にて得られた、貯蔵弾性率曲線と損失弾性率曲線との交点における温度Ｔと、改質されたポリ乳酸系樹脂の融点（ｍｐ）とが上記式１を満たすように調整するのが好ましい理由を下記に詳述する。   Furthermore, the temperature T at the intersection of the storage elastic modulus curve and the loss elastic modulus curve obtained by the dynamic viscoelasticity measurement of the modified polylactic acid resin, and the melting point of the modified polylactic acid resin ( The reason why it is preferable to adjust so that mp) satisfies the above equation 1 will be described in detail below.

先ず、改質されたポリ乳酸系樹脂の動的粘弾性測定にて得られた、貯蔵弾性率曲線と損失弾性率曲線との交点における温度Ｔが、改質されたポリ乳酸系樹脂の融点（ｍｐ）よりも４０℃を越えて低い場合には、押出発泡時におけるポリ乳酸系樹脂の損失弾性率が貯蔵弾性率に比して大き過ぎるために、損失弾性率と貯蔵弾性率とのバランスが崩れてしまう。   First, the temperature T at the intersection of the storage elastic modulus curve and the loss elastic modulus curve obtained by dynamic viscoelasticity measurement of the modified polylactic acid resin is the melting point of the modified polylactic acid resin ( mp) below 40 ° C., the loss elastic modulus of the polylactic acid resin at the time of extrusion foaming is too large compared to the storage elastic modulus, so the balance between the loss elastic modulus and the storage elastic modulus is It will collapse.

そこで、ポリ乳酸系樹脂の損失弾性率に適した発泡力、即ち、ポリ乳酸系樹脂の粘性に合わせた発泡力とすると、ポリ乳酸系樹脂の弾性力にとっては発泡力が大き過ぎてしまい、気泡膜が破れて破泡を生じて良好なポリ乳酸系樹脂発泡粒子を得ることができず、逆に、ポリ乳酸系樹脂の貯蔵弾性率に適した発泡力、即ち、ポリ乳酸系樹脂の弾性に合わせた発泡力とすると、ポリ乳酸系樹脂の粘性力にとっては発泡力が小さく、ポリ乳酸系樹脂が発泡しにくくなり、やはり良好なポリ乳酸系樹脂発泡粒子を得ることが困難となる。   Therefore, if the foaming force suitable for the loss elastic modulus of the polylactic acid-based resin, that is, the foaming force matched to the viscosity of the polylactic acid-based resin, the foaming force is too large for the elastic force of the polylactic acid-based resin. The film is broken and bubbles are broken, and good polylactic acid resin expanded particles cannot be obtained. Conversely, the foaming force suitable for the storage elastic modulus of the polylactic acid resin, that is, the elasticity of the polylactic acid resin is reduced. If the combined foaming force is used, the foaming force is small for the viscosity of the polylactic acid-based resin, the polylactic acid-based resin is difficult to foam, and it is difficult to obtain good polylactic acid-based resin foamed particles.

又、改質されたポリ乳酸系樹脂の動的粘弾性測定にて得られた、貯蔵弾性率曲線と損失弾性率曲線との交点における温度Ｔが、改質されたポリ乳酸系樹脂の融点（ｍｐ）よりも高いと、押出発泡時におけるポリ乳酸系樹脂の貯蔵弾性率が損失弾性率に比して大き過ぎるために、上述と同様に損失弾性率と貯蔵弾性率とのバランスが崩れてしまう。   In addition, the temperature T at the intersection of the storage elastic modulus curve and the loss elastic modulus curve obtained by dynamic viscoelasticity measurement of the modified polylactic acid resin is the melting point of the modified polylactic acid resin ( mp), the storage elastic modulus of the polylactic acid resin at the time of extrusion foaming is too large compared to the loss elastic modulus, so that the balance between the loss elastic modulus and the storage elastic modulus is lost as described above. .

そこで、ポリ乳酸系樹脂の貯蔵弾性率に適した発泡力、即ち、ポリ乳酸系樹脂の弾性に合わせた発泡力とすると、ポリ乳酸系樹脂の粘性力にとっては発泡力が大き過ぎてしまい、気泡膜が破れて破泡を生じ良好なポリ乳酸系樹脂発泡粒子を得ることができず、逆に、ポリ乳酸系樹脂の損失弾性率に適した発泡力、即ち、ポリ乳酸系樹脂の粘性に合わせた発泡力とすると、ポリ乳酸系樹脂の弾性力にとっては発泡力が小さく、ポリ乳酸系樹脂が発泡力で一旦、発泡したとしても、経時的な発泡力の低下に伴って気泡が収縮してしまって、やはり良好なポリ乳酸系樹脂発泡粒子を得ることが困難となる。   Therefore, if the foaming force suitable for the storage elastic modulus of the polylactic acid-based resin, that is, the foaming force matched to the elasticity of the polylactic acid-based resin, the foaming force is too large for the viscosity force of the polylactic acid-based resin, The film is broken and bubbles are broken, and good polylactic acid resin foam particles cannot be obtained. Conversely, the foaming force suitable for the loss elastic modulus of the polylactic acid resin, that is, the viscosity of the polylactic acid resin is adjusted. If the foaming force is high, the foaming force is small for the elastic force of the polylactic acid-based resin. Even if the polylactic acid-based resin foams once due to the foaming force, the bubbles shrink as the foaming force decreases over time. In other words, it becomes difficult to obtain good polylactic acid resin expanded particles.

そして、エポキシ基を有するアクリル・スチレン系化合物によって改質されたポリ乳酸系樹脂の動的粘弾性測定にて得られた、貯蔵弾性率曲線と損失弾性率曲線との交点における温度Ｔと、改質されたポリ乳酸系樹脂の融点（ｍｐ）とが上記式１を満たすように調整する方法としては、前述したように、エポキシ基を有するアクリル・スチレン系化合物の押出機への供給量を調整する方法の他に、ポリ乳酸系樹脂とエポキシ基を有するアクリル・スチレン系化合物とが反応する押出機部分、即ち、押出機の圧縮部の温度を調整する方法が挙げられる。   Then, the temperature T at the intersection of the storage elastic modulus curve and the loss elastic modulus curve obtained by dynamic viscoelasticity measurement of the polylactic acid resin modified with the acrylic / styrene compound having an epoxy group, As a method of adjusting the melting point (mp) of the obtained polylactic acid resin to satisfy the above formula 1, as described above, the supply amount of the acrylic / styrene compound having an epoxy group to the extruder is adjusted. In addition to the method, there is a method of adjusting the temperature of the extruder part where the polylactic acid resin and the acrylic / styrene compound having an epoxy group react, that is, the compression part of the extruder.

押出機の圧縮部の温度は、低いと、ポリ乳酸系樹脂とエポキシ基を有するアクリル・スチレン系化合物との反応が不充分となり、ポリ乳酸系樹脂の粘弾性の改質効果が低下することがある一方、高いと、ポリ乳酸系樹脂が分解して分子量が低下し、ポリ乳酸系樹脂の発泡性が低下することがあるので、２００〜２５０℃が好ましく、２１０〜２４０℃がより好ましく、２１５〜２３５℃が特に好ましい。   If the temperature of the compression section of the extruder is low, the reaction between the polylactic acid resin and the acrylic / styrene compound having an epoxy group becomes insufficient, and the effect of modifying the viscoelasticity of the polylactic acid resin may be reduced. On the other hand, if it is high, the polylactic acid resin is decomposed to lower the molecular weight, and the foamability of the polylactic acid resin may be lowered. Therefore, 200 to 250 ° C is preferable, 210 to 240 ° C is more preferable, and 215 ˜235 ° C. is particularly preferred.

ここで、ポリ乳酸系樹脂の融点（ｍｐ）は下記の要領で測定されたものをいう。即ち、ＪＩＳ Ｋ７１２１：１９８７に準拠してポリ乳酸系樹脂の示差走査熱量分析を行い、得られたＤＳＣ曲線における融解ピークの温度をポリ乳酸系樹脂の融点（ｍｐ）とする。なお、融解ピークの温度が複数個ある場合には、最も高い温度とする。   Here, the melting point (mp) of the polylactic acid resin is measured in the following manner. That is, the differential scanning calorimetry of the polylactic acid resin is performed in accordance with JIS K7121: 1987, and the melting peak temperature in the obtained DSC curve is defined as the melting point (mp) of the polylactic acid resin. When there are a plurality of melting peak temperatures, the highest temperature is set.

又、改質されたポリ乳酸系樹脂の動的粘弾性測定にて得られた、貯蔵弾性率曲線と損失弾性率曲線との交点における温度Ｔは下記の要領で測定されたものをいう。先ず、ポリ乳酸系樹脂発泡粒子を製造する要領において、発泡剤を添加しないこと以外は同様の要領にて、改質されたポリ乳酸系樹脂粒子を得る。   Further, the temperature T at the intersection of the storage elastic modulus curve and the loss elastic modulus curve obtained by the dynamic viscoelasticity measurement of the modified polylactic acid-based resin means that measured in the following manner. First, modified polylactic acid resin particles are obtained in the same manner except that the foaming agent is not added in the procedure for producing the polylactic acid resin expanded particles.

この改質されたポリ乳酸系樹脂粒子を９．３３×１０4 Ｐａの減圧下にて８０℃で３時間に亘って乾燥する。この改質されたポリ乳酸系樹脂粒子を該ポリ乳酸系樹脂粒子を構成しているポリ乳酸系樹脂の融点よりも４０〜５０℃だけ高い温度に加熱した測定プレート上に載置して窒素雰囲気下にて５分間に亘って放置し溶融させる。 This modified polylactic acid resin particles to dry for three hours at 80 ° C. under reduced pressure of 9.33 × 10 4 Pa. The modified polylactic acid resin particles are placed on a measurement plate heated to a temperature 40 to 50 ° C. higher than the melting point of the polylactic acid resin constituting the polylactic acid resin particles, and a nitrogen atmosphere Allow to melt for 5 minutes underneath.

次に、直径が２５ｍｍの平面円形状の押圧板を用意し、この押圧板を用いて測定プレート上のポリ乳酸系樹脂を押圧板と測定プレートとの対向面間の間隔が１ｍｍとなるまで上下方向に押圧する。そして、押圧板の外周縁からはみ出したポリ乳酸系樹脂を除去した後、５分間に亘って放置する。   Next, a flat circular pressure plate having a diameter of 25 mm is prepared, and the polylactic acid resin on the measurement plate is moved up and down until the distance between the opposing surfaces of the pressure plate and the measurement plate becomes 1 mm. Press in the direction. And after removing the polylactic acid-type resin which protruded from the outer periphery of a press plate, it is left to stand for 5 minutes.

しかる後、歪み５％、周波数１ｒａｄ／秒、降温速度２℃／分、測定間隔３０秒の条件下にて、ポリ乳酸系樹脂の動的粘弾性測定を行って貯蔵弾性率及び損失弾性率を測定する。次に、横軸を温度とし、縦軸を貯蔵弾性率及び損失弾性率として、貯蔵弾性率曲線及び損失弾性率曲線を描く。なお、貯蔵弾性率曲線及び損失弾性率曲線を描くにあたっては、測定温度を基準として互いに隣接する測定値同士を直線で結ぶ。   Thereafter, the dynamic viscoelasticity measurement of the polylactic acid resin is performed under the conditions of 5% strain, frequency 1 rad / sec, temperature drop rate 2 ° C./min, and measurement interval 30 sec to determine the storage elastic modulus and loss elastic modulus. taking measurement. Next, a storage elastic modulus curve and a loss elastic modulus curve are drawn with the horizontal axis as temperature and the vertical axis as storage elastic modulus and loss elastic modulus. In drawing the storage elastic modulus curve and the loss elastic modulus curve, the measurement values adjacent to each other are connected with a straight line based on the measurement temperature.

そして、得られた貯蔵弾性率曲線と損失弾性率曲線との交点における温度Ｔを上記グラフから読み取ることによって得ることができる。なお、貯蔵弾性率曲線と損失弾性率曲線とが複数箇所において互いに交差する場合は、貯蔵弾性率曲線と損失弾性率曲線との複数の交点における温度のうち最も高い温度を、貯蔵弾性率曲線と損失弾性率曲線との交点における温度Ｔとする。   And it can obtain by reading the temperature T in the intersection of the obtained storage elastic modulus curve and loss elastic modulus curve from the said graph. When the storage modulus curve and the loss modulus curve intersect each other at a plurality of locations, the highest temperature among the temperatures at the plurality of intersections of the storage modulus curve and the loss modulus curve is defined as the storage modulus curve. It is set as the temperature T in the intersection with a loss elastic modulus curve.

又、動的粘弾性測定にて得られた、貯蔵弾性率曲線と損失弾性率曲線との交点における温度Ｔは、Reologica Instruments A.B 社から商品名「DynAlyser DAR-100」 にて市販されている動的粘弾性測定装置を用いて測定することができる。   The temperature T at the intersection of the storage elastic modulus curve and the loss elastic modulus curve obtained by dynamic viscoelasticity measurement is a dynamic value commercially available from Reologica Instruments AB under the trade name “DynAlyser DAR-100”. It can be measured using a mechanical viscoelasticity measuring device.

上記ポリ乳酸系樹脂を押出機に供給して発泡剤の存在下にて溶融混練した後、押出機の先端に取り付けた金型から押出発泡させる。この押出発泡させて得られた押出発泡体の形態は、特に限定されず、ストランド状、シート状などが挙げられるが、ストランド状が好ましい。   The polylactic acid-based resin is supplied to an extruder, melted and kneaded in the presence of a foaming agent, and then extruded and foamed from a mold attached to the tip of the extruder. The form of the extruded foam obtained by extrusion foaming is not particularly limited, and examples thereof include a strand shape and a sheet shape, and a strand shape is preferable.

なお、上記押出機としては、従来から汎用されている押出機であれば、特に限定されず、例えば、単軸押出機、二軸押出機、複数の押出機を連結させたタンデム型の押出機が挙げられ、タンデム型の押出機が好ましい。   The extruder is not particularly limited as long as it is a conventionally used extruder. For example, a single-screw extruder, a twin-screw extruder, and a tandem extruder in which a plurality of extruders are connected. A tandem type extruder is preferable.

又、上記発泡剤としては、従来から汎用されているものが用いられ、例えば、アゾジカルボンアミド、ジニトロソペンタメチレンテトラミン、ヒドラゾイルジカルボンアミド、重炭酸ナトリウムなどの化学発泡剤；プロパン、ノルマルブタン、イソブタン、ノルマルペンタン、イソペンタン、ヘキサンなどの飽和脂肪族炭化水素、ジメチルエーテルなどのエーテル類、塩化メチル、１，１，１，２−テトラフルオロエタン、１，１−ジフルオロエタン、モノクロロジフルオロメタンなどのフロン、二酸化炭素、窒素などの物理発泡剤などが挙げられ、ジメチルエーテル、プロパン、ノルマルブタン、イソブタン、二酸化炭素が好ましく、プロパン、ノルマルブタン、イソブタンがより好ましく、ノルマルブタン、イソブタンが特に好ましい。   Further, as the foaming agent, those conventionally used are used, for example, chemical foaming agents such as azodicarbonamide, dinitrosopentamethylenetetramine, hydrazoyldicarbonamide, sodium bicarbonate; propane, normal butane, Saturated aliphatic hydrocarbons such as isobutane, normal pentane, isopentane, hexane, ethers such as dimethyl ether, chlorofluorocarbons such as methyl chloride, 1,1,1,2-tetrafluoroethane, 1,1-difluoroethane, monochlorodifluoromethane, Examples thereof include physical blowing agents such as carbon dioxide and nitrogen, dimethyl ether, propane, normal butane, isobutane and carbon dioxide are preferred, propane, normal butane and isobutane are more preferred, and normal butane and isobutane are particularly preferred.

そして、押出機に供給される発泡剤量としては、少ないと、ポリ乳酸系樹脂発泡粒子を所望発泡倍率まで発泡させることができないことがある一方、多いと、発泡剤が可塑剤として作用することから溶融状態のポリ乳酸系樹脂の粘弾性が低下し過ぎて発泡性が低下し良好なポリ乳酸系樹脂発泡粒子を得ることができなかったり或いはポリ乳酸系樹脂発泡粒子の発泡倍率が高過ぎる場合があるので、ポリ乳酸系樹脂１００重量部に対して０．１〜５重量部が好ましく、０．２〜４重量部がより好ましく、０．３〜３重量部が特に好ましい。   If the amount of foaming agent supplied to the extruder is small, the polylactic acid resin foamed particles may not be foamed to the desired foaming ratio, while if large, the foaming agent acts as a plasticizer. When the melted polylactic acid-based resin has too low viscoelasticity and foamability is reduced, and good polylactic acid-based resin expanded particles cannot be obtained, or the expansion ratio of the polylactic acid-based resin expanded particles is too high Therefore, the amount is preferably 0.1 to 5 parts by weight, more preferably 0.2 to 4 parts by weight, and particularly preferably 0.3 to 3 parts by weight with respect to 100 parts by weight of the polylactic acid resin.

なお、押出機には気泡調整剤が添加されることが好ましいが、気泡調整剤の多くは、ポリ乳酸系樹脂発泡粒子の結晶核剤として作用するため、ポリ乳酸系樹脂の結晶化を促進しない気泡調整剤を用いることが好ましく、このような気泡調整剤としては、ポリテトラフルオロエチレン粉末、アクリル樹脂で変性されたポリテトラフルオロエチレン粉末が好ましい。   In addition, it is preferable that a bubble regulator is added to the extruder, but since many of the bubble regulators act as crystal nucleating agents for the polylactic acid resin foamed particles, crystallization of the polylactic acid resin is not promoted. It is preferable to use a bubble regulator, and as such a bubble regulator, polytetrafluoroethylene powder or polytetrafluoroethylene powder modified with an acrylic resin is preferred.

更に、ポリテトラフルオロエチレン粉末、アクリル樹脂で変性されたポリテトラフルオロエチレン粉末は、エポキシ基を有するアクリル・スチレン系化合物と併用することによって、エポキシ基を有するアクリル・スチレン系化合物のポリ乳酸系樹脂に対する動的粘弾性の改質効果を促進することができる。   In addition, polytetrafluoroethylene powder and polytetrafluoroethylene powder modified with acrylic resin can be used together with acrylic / styrene compound having epoxy group, so that polylactic acid resin of acrylic / styrene compound having epoxy group can be used. The effect of modifying the dynamic viscoelasticity with respect to can be accelerated.

これは、ポリテトラフルオロエチレン粉末や、アクリル樹脂で変性されたポリテトラフルオロエチレン粉末は、押出機内において加えられる剪断応力によって繊維状となり、この繊維状のポリテトラフルオロエチレンは、エポキシ基を有するアクリル・スチレン系化合物により改質されたポリ乳酸系樹脂の分子鎖に絡みつき、ポリ乳酸系樹脂の溶融張力を高めることによってポリ乳酸系樹脂の動的粘弾性の改質を促進するからである。   This is because polytetrafluoroethylene powder or polytetrafluoroethylene powder modified with an acrylic resin becomes fibrous due to shear stress applied in the extruder, and this fibrous polytetrafluoroethylene is an acrylic having an epoxy group. This is because the modification of the dynamic viscoelasticity of the polylactic acid resin is promoted by entanglement with the molecular chain of the polylactic acid resin modified with the styrene compound and increasing the melt tension of the polylactic acid resin.

又、押出機に供給される気泡調整剤の量としては、少ないと、ポリ乳酸系樹脂発泡粒子の気泡が粗大となり、得られるポリ乳酸系樹脂発泡成形体の外観が低下することがある一方、多いと、ポリ乳酸系樹脂を押出発泡させる際に破泡を生じてポリ乳酸系樹脂発泡粒子の独立気泡率が低下することがあるので、ポリ乳酸系樹脂１００重量部に対して０．０１〜３重量部が好ましく、０．０５〜２重量部がより好ましく、０．１〜１重量部が特に好ましい。   In addition, as the amount of the air conditioner supplied to the extruder, if the amount is small, the bubbles of the polylactic acid-based resin expanded particles become coarse, and the appearance of the resulting polylactic acid-based resin foam molded product may be deteriorated, If the amount is too large, bubbles may be broken when the polylactic acid-based resin is extruded and foamed, and the closed cell ratio of the polylactic acid-based resin foamed particles may be reduced, so 0.01 to 100 parts by weight of the polylactic acid-based resin. 3 parts by weight is preferable, 0.05 to 2 parts by weight is more preferable, and 0.1 to 1 part by weight is particularly preferable.

押出機に取り付ける金型としては、特に限定されないが、ポリ乳酸系樹脂を押出発泡させて均一微細な気泡を形成できる金型が好ましく、このような金型としては、ノズル金型が好ましく、ノズルを複数有するマルチノズル金型がより好ましい。   The mold attached to the extruder is not particularly limited, but a mold capable of forming uniform fine bubbles by extrusion foaming a polylactic acid-based resin is preferable. As such a mold, a nozzle mold is preferable, and a nozzle A multi-nozzle mold having a plurality of is more preferable.

マルチノズル金型のノズルの出口直径は、小さいと、押出圧力が高くなりすぎて押出発泡が困難となることがある一方、大きいと、ポリ乳酸系樹脂発泡粒子の径が大きくなって金型への充填性が低下するので、０．２〜２ｍｍが好ましく、０．３〜１．６ｍｍがより好ましく、０．４〜１．２ｍｍが特に好ましい。   If the outlet diameter of the nozzle of the multi-nozzle mold is small, the extrusion pressure may become too high and extrusion foaming may become difficult. Therefore, 0.2 to 2 mm is preferable, 0.3 to 1.6 mm is more preferable, and 0.4 to 1.2 mm is particularly preferable.

そして、ノズル金型のノズルの口金出口部分におけるポリ乳酸系樹脂の剪断速度は、小さいと、ポリ乳酸系樹脂発泡粒子の発泡倍率が低下し或いはポリ乳酸系樹脂発泡粒子の気泡が粗大となることがある一方、大きいと、フラクチャーが発生して安定的に押出発泡することができないことがあるので、１０００〜３００００ｓｅｃ-1が好ましく、２０００〜２５０００ｓｅｃ-1がより好ましく、３０００〜２００００ｓｅｃ-1が特に好ましい。 If the shear rate of the polylactic acid-based resin at the nozzle outlet portion of the nozzle of the nozzle mold is small, the expansion ratio of the polylactic acid-based resin foamed particles is reduced or the bubbles of the polylactic acid-based resin expanded particles are coarse. On the other hand, if it is large, fracture may occur and stable extrusion foaming may not be possible, so 1000 to 30000 sec -1 is preferable, 2000 to 25000 sec -1 is more preferable, and 3000 to 20000 sec -1 is particularly preferable. preferable.

なお、ノズル金型のノズルの口金出口部分における剪断速度は、下記式に基づいて算出されたものをいう。
剪断速度（ｓｅｃ-1）＝４×Ｑ／（πｒ3 ）
但し、Ｑは、ポリ乳酸系樹脂の体積押出量（ｃｍ3 ／ｓｅｃ）であり（Ｑを質量押出量（ｇ／ｓｅｃ）から算出する場合は、ポリ乳酸系樹脂の密度は１．０ｇ／ｃｍ3 とする）、ｒは、ノズルの半径（ｃｍ）である。 In addition, the shear rate in the nozzle | cap | die exit part of the nozzle of a nozzle metal mold | die says what was computed based on the following formula.
Shear rate (sec −1 ) = 4 × Q / (πr 3 )
However, Q is the volume extrusion rate (cm 3 / sec) of the polylactic acid-based resin (when Q is calculated from the mass extrusion rate (g / sec), the density of the polylactic acid-based resin is 1.0 g / cm 3 ), r is the radius (cm) of the nozzle.

又、フラクチャーを低減させるために、ノズル金型のランド部の長さは、ノズル金型のノズルの出口直径の４〜３０倍が好ましく、ノズル金型のノズルの出口直径の５〜２０倍がより好ましい。これは、ノズル金型のランド部の長さがノズル金型のノズルの出口直径に比較して小さいと、フラクチャーが発生して安定的に押出発泡することができないことがある一方、ノズル金型のランド部の長さがノズル金型のノズルの出口直径に比較して大きいと、ノズル金型に大きな圧力が加わり過ぎて押出発泡ができない場合があるからである。   In order to reduce fracture, the length of the land portion of the nozzle mold is preferably 4 to 30 times the nozzle outlet diameter of the nozzle mold, and 5 to 20 times the nozzle outlet diameter of the nozzle mold. More preferred. This is because when the length of the land portion of the nozzle mold is smaller than the nozzle outlet diameter of the nozzle mold, fracturing occurs and the foam cannot be stably extruded. This is because if the length of the land portion is larger than the outlet diameter of the nozzle of the nozzle mold, excessive pressure may be applied to the nozzle mold to prevent extrusion foaming.

そして、押出機から押出発泡されたポリ乳酸系樹脂押出発泡体を冷却して、ポリ乳酸系樹脂押出発泡体の結晶化が進行するのを抑制し、このポリ乳酸系樹脂押出発泡体を粒子状に切断して得られるポリ乳酸系樹脂発泡粒子の結晶化度が３０％未満となるように、好ましくは３〜２８％となるように、より好ましくは５〜２６％となるように調整する。   Then, the polylactic acid resin extruded foam extruded from the extruder is cooled to suppress the crystallization of the polylactic acid resin extruded foam, and the polylactic acid resin extruded foam is formed into particles. It adjusts so that it may become 3 to 28%, More preferably, it may become 5 to 26% so that the crystallinity degree of the polylactic acid-type resin expanded particle obtained by cutting | disconnecting to less than 30%.

ここで、ポリ乳酸系樹脂発泡粒子の結晶化度は、示差走査熱量計（ＤＳＣ）を用いてＪＩＳ Ｋ７１２１に記載の測定方法に準拠して１０℃／分の昇温速度にて昇温しながら測定された１ｍｇ当たりの冷結晶化熱量及び１ｍｇ当たりの融解熱量に基づいて下記式により算出することができる。   Here, the degree of crystallinity of the polylactic acid-based resin expanded particles is measured while using a differential scanning calorimeter (DSC) while raising the temperature at a rate of temperature increase of 10 ° C./min according to the measurement method described in JIS K7121. Based on the measured amount of cold crystallization per 1 mg and heat of fusion per 1 mg, it can be calculated by the following formula.

Figure 2007169394
Figure 2007169394

このように、得られるポリ乳酸系樹脂発泡粒子の結晶化度を３０％未満に調整することによって、ポリ乳酸系樹脂発泡粒子の融着性を確保し、型内発泡成形時、ポリ乳酸系樹脂発泡粒子を発泡させて得られる発泡粒子同士の融着性を良好なものとすることができる。又、型内発泡成形途上において、ポリ乳酸系樹脂発泡粒子の結晶化度を上昇させて、ポリ乳酸系樹脂の耐熱性を向上させることができ、得られるポリ乳酸系樹脂発泡成形体は、優れた融着性及び耐熱性を有している。   Thus, by adjusting the crystallinity of the obtained polylactic acid-based resin expanded particles to less than 30%, the fusion property of the polylactic acid-based resin expanded particles is ensured, and during the in-mold foam molding, The fusibility between the foamed particles obtained by foaming the foamed particles can be improved. In addition, during the in-mold foam molding process, the crystallinity of the polylactic acid resin foamed particles can be increased to improve the heat resistance of the polylactic acid resin, and the resulting polylactic acid resin foam molding is excellent. It has excellent fusion and heat resistance.

そして、ポリ乳酸系樹脂押出発泡体の冷却方法としては、押出発泡されたポリ乳酸系樹脂押出発泡体の結晶化度の上昇を速やかに停止できる方法が好ましく、具体的には、押出機から押出発泡されたポリ乳酸系樹脂押出発泡体を水面に浮かせて冷却する方法、押出機から押出発泡されたポリ乳酸系樹脂押出発泡体に水などを霧状に吹き付ける方法、低温に温度調節された冷却板上に、押出機から押出発泡されたポリ乳酸系樹脂押出発泡体を接触させることによって冷却させる方法、押出機から押出発泡された押出発泡体に冷風などの冷却された気体を吹き付ける方法などが挙げられる。なお、ポリ乳酸系樹脂押出発泡体を水面に浮かせて冷却する場合は、水温は０〜４５℃に調整することが好ましい。   The cooling method for the extruded polylactic acid resin foam is preferably a method capable of quickly stopping the increase in the degree of crystallinity of the extruded foam of the polylactic acid resin foam. A method of cooling the foamed polylactic acid resin foam by floating it on the water surface, a method of spraying water or the like on the extruded polylactic acid resin foam foamed from an extruder, and a cooling controlled to a low temperature A method of cooling a polylactic acid resin extruded foam that has been extruded and foamed from an extruder on a plate, a method of blowing a cooled gas such as cold air onto an extruded foam that has been extruded and foamed from an extruder, etc. Can be mentioned. In addition, when making a polylactic acid-type resin extrusion foaming body float on the water surface and cooling, it is preferable to adjust water temperature to 0-45 degreeC.

次に、上述のようにして冷却されたポリ乳酸系樹脂押出発泡体を粒子状に切断することによってポリ乳酸系樹脂発泡粒子を得ることができる。ポリ乳酸系樹脂押出発泡体を粒子状に切断する切断機としては、ペレタイザーやホットカット機などが挙げられ、又、切断機の切断方法としては、ドラムカッタ式やファンカッタ式があるが、ポリ乳酸系樹脂押出発泡体の切断時にポリ乳酸系樹脂押出発泡体に割れや欠けが発生しにくいことから、ファンカッタ式の切断方法を用いることが好ましい。なお、上記では、ポリ乳酸系樹脂押出発泡体の冷却後に、ポリ乳酸系樹脂押出発泡体を切断する場合を説明したが、押出機から押出発泡させると同時にポリ乳酸系樹脂押出発泡体を切断して粒子状とした後に、ポリ乳酸系樹脂発泡粒子を冷却するようにしてもよい。   Next, polylactic acid resin foamed particles can be obtained by cutting the extruded polylactic acid resin foam as described above into particles. Examples of the cutting machine that cuts the extruded polylactic acid resin into particles include a pelletizer and a hot-cut machine. The cutting methods of the cutting machine include a drum cutter type and a fan cutter type. It is preferable to use a fan-cutter-type cutting method because cracking and chipping are less likely to occur in the extruded polylactic acid resin foam when cutting the extruded lactic acid resin foam. In the above description, the case where the polylactic acid resin extruded foam is cut after cooling the polylactic acid resin extruded foam has been described. However, the polylactic acid resin extruded foam is cut simultaneously with the extrusion foaming from the extruder. Then, the polylactic acid resin foamed particles may be cooled after being made into particles.

このようにして得られたポリ乳酸系樹脂発泡粒子の嵩密度は、小さいと、ポリ乳酸系樹脂発泡粒子の連続気泡率が上昇して、型内発泡成形における発泡時にポリ乳酸系樹脂発泡粒子に必要な発泡力を付与することができない虞れがある一方、大きいと、得られるポリ乳酸系樹脂発泡粒子の気泡が不均一となって、型内発泡成形時におけるポリ乳酸系樹脂発泡粒子の発泡性が不充分となることがあるので、０．０３〜０．５ｇ／ｃｍ3 が好ましく、０．０５〜０．４ｇ／ｃｍ3 がより好ましく、０．０７〜０．３ｇ／ｃｍ3 が特に好ましい。 If the bulk density of the polylactic acid-based resin expanded particles obtained in this way is small, the open cell ratio of the polylactic acid-based resin expanded particles increases, and the polylactic acid-based resin expanded particles become foamed during foaming in in-mold foam molding. On the other hand, there is a possibility that the necessary foaming force cannot be imparted. On the other hand, if it is large, the resulting foam of the polylactic acid resin foamed particles becomes uneven, and foaming of the polylactic acid resin foamed particles during in-mold foam molding 0.03 to 0.5 g / cm 3 is preferable, 0.05 to 0.4 g / cm 3 is more preferable, and 0.07 to 0.3 g / cm 3 is particularly preferable. preferable.

そして、ポリ乳酸系樹脂発泡粒子の連続気泡率は、高いと、型内発泡成形時にポリ乳酸系樹脂発泡粒子が殆ど発泡せず、ポリ乳酸系樹脂発泡粒子同士の融着性が低くなって、得られるポリ乳酸系樹脂発泡成形体の機械的強度が低下することがあるので、３０％未満に限定され、２８％以下がより好ましく、２６％以下が特に好ましい。なお、ポリ乳酸系樹脂発泡粒子の連続気泡率の調整は、エポキシ基を有するアクリル・スチレン系化合物の押出機への供給量を調整する他に、押出機からのポリ乳酸系樹脂の押出発泡温度、金型の形状、押出機への発泡剤の供給量などを調整することによって行われる。   And when the open cell ratio of the polylactic acid-based resin expanded particles is high, the polylactic acid-based resin expanded particles hardly foam at the time of in-mold foam molding, and the fusion property between the polylactic acid-based resin expanded particles becomes low, Since the mechanical strength of the obtained polylactic acid-based resin foam molded article may be lowered, it is limited to less than 30%, more preferably 28% or less, and particularly preferably 26% or less. In addition, the adjustment of the open cell ratio of the polylactic acid resin expanded particles is not only the adjustment of the supply amount of the acrylic / styrene compound having an epoxy group to the extruder, but also the extrusion foaming temperature of the polylactic acid resin from the extruder. It is performed by adjusting the shape of the mold, the amount of foaming agent supplied to the extruder, and the like.

ここで、ポリ乳酸系樹脂発泡粒子の連続気泡率は下記の要領で測定される。先ず、体積測定空気比較式比重計の試料カップを用意し、この試料カップの８０％程度を満たす量のポリ乳酸系樹脂発泡粒子の全重量Ａ（ｇ）を測定する。次に、上記ポリ乳酸系樹脂発泡粒子全体の体積Ｂ（ｃｍ3 ）を比重計を用いて１−１／２−１気圧法により測定する。なお、体積測定空気比較式比重計は、例えば、東京サイエンス社から商品名「１０００型」にて市販されている。 Here, the open cell ratio of the polylactic acid-based resin expanded particles is measured in the following manner. First, a sample cup of a volumetric air comparison type hydrometer is prepared, and the total weight A (g) of polylactic acid resin expanded particles in an amount satisfying about 80% of the sample cup is measured. Next, the volume B (cm 3 ) of the whole polylactic acid-based resin expanded particles is measured by a 1-1 / 2-1 atmospheric pressure method using a hydrometer. The volumetric air comparison type hydrometer is commercially available, for example, from Tokyo Science Co. under the trade name “1000 type”.

続いて、金網製の容器を用意し、この金網製の容器を水中に浸漬し、この水中に浸漬した状態における金網製の容器の重量Ｃ（ｇ）を測定する。次に、この金網製の容器内に上記ポリ乳酸系樹脂発泡粒子を全量入れた上で、この金網製の容器を水中に浸漬し、水中に浸漬した状態における金網製の容器とこの金網製容器に入れたポリ乳酸系樹脂発泡粒子の全量とを併せた重量Ｄ（ｇ）を測定する。   Subsequently, a wire mesh container is prepared, the wire mesh container is immersed in water, and the weight C (g) of the wire mesh container in the state immersed in the water is measured. Next, after all the polylactic acid-based resin expanded particles are put in the wire mesh container, the wire mesh container is immersed in water, and the wire mesh container and the wire mesh container are immersed in water. The weight D (g) of the total amount of the polylactic acid-based resin expanded particles put in the container is measured.

そして、下記式に基づいてポリ乳酸系樹脂発泡粒子の見掛け体積Ｅ（ｃｍ3 ）を算出し、この見掛け体積Ｅと上記ポリ乳酸系樹脂発泡粒子全体の体積Ｂ（ｃｍ3 ）に基づいて下記式によりポリ乳酸系樹脂発泡粒子の連続気泡率を算出することができる。なお、水１ｇの体積を１ｃｍ3 とした。
Ｅ＝Ａ＋（Ｃ−Ｄ）
連続気泡率（％）＝１００×（Ｅ−Ｂ）／Ｅ Then, the apparent volume E (cm 3 ) of the polylactic acid-based resin expanded particles is calculated based on the following formula, and the following formula is calculated based on this apparent volume E and the volume B (cm 3 ) of the entire polylactic acid-based resin expanded particles. Thus, the open cell ratio of the polylactic acid-based resin expanded particles can be calculated. The volume of 1 g of water was 1 cm 3 .
E = A + (CD)
Open cell ratio (%) = 100 × (EB) / E

又、上記ポリ乳酸系樹脂発泡粒子の粒径は、小さいと、型内発泡成形時にポリ乳酸系樹脂発泡粒子の発泡性が低下することがある一方、大きいと、型内発泡成形時に金型内へのポリ乳酸系樹脂発泡粒子の充填性が低下することがあるので、１．０〜５．０ｍｍが好ましい。そして、押出発泡体がストランド状であり、このストランド状の押出発泡体をその長さ方向に所定間隔毎に切断してポリ乳酸系樹脂発泡粒子を製造した場合、ポリ乳酸系樹脂発泡粒子における切断面に直交する方向の長さは、５ｍｍ以下が好ましい。   In addition, if the particle diameter of the polylactic acid-based resin expanded particles is small, the foamability of the polylactic acid-based resin expanded particles may be reduced during in-mold foam molding. Since the filling property of the polylactic acid-based resin foamed particles may be lowered, 1.0 to 5.0 mm is preferable. When the extruded foam is in the form of a strand, and the polylactic acid resin foamed particles are produced by cutting the strand-shaped extruded foam at predetermined intervals in the length direction, cutting in the polylactic acid resin foamed particles The length in the direction perpendicular to the surface is preferably 5 mm or less.

ここで、ポリ乳酸系樹脂発泡粒子の粒径は、ポリ乳酸系樹脂発泡粒子の直径を直接、ノギスを用いて測定することができる。なお、押出発泡体がストランド状であり、このストランド状の押出発泡体をその長さ方向に所定間隔毎に切断してポリ乳酸系樹脂発泡粒子を製造した場合には、各ポリ乳酸系樹脂発泡粒子の切断面における最も長い直径（長径）及び最も短い直径（短径）を測定すると共に、各ポリ乳酸系樹脂発泡粒子における切断面に直交する方向の長さを測定し、ポリ乳酸系樹脂発泡粒子の長径、短径及び長さの相加平均値をポリ乳酸系樹脂発泡粒子の粒径とする。   Here, the particle diameter of the polylactic acid-based resin expanded particles can be measured directly using a caliper with the diameter of the polylactic acid-based resin expanded particles. In addition, when the extruded foam is in the form of a strand, and the strand-shaped extruded foam is cut at predetermined intervals in the length direction, the polylactic acid resin foamed particles are produced. While measuring the longest diameter (major axis) and the shortest diameter (minor axis) at the cut surface of the particle, the length of each polylactic acid resin foamed particle in the direction perpendicular to the cut surface is measured, and the polylactic acid resin foam The arithmetic average value of the major axis, minor axis and length of the particles is taken as the particle size of the polylactic acid-based resin expanded particles.

このようにして得られたポリ乳酸系樹脂発泡粒子を金型のキャビティ内に充填して加熱し、ポリ乳酸系樹脂発泡粒子を発泡させることによって、ポリ乳酸系樹脂発泡粒子を発泡させて得られる発泡粒子同士をそれらの発泡圧によって互いに融着一体化させると共にポリ乳酸系樹脂の結晶化度を上昇させて、融着性及び耐熱性に優れた所望形状を有するポリ乳酸系樹脂発泡成形体を得ることができる。   Obtained by foaming the polylactic acid-based resin foamed particles by filling the polylactic acid-based resin foamed particles thus obtained into a mold cavity and heating the foamed polylactic acid-based resin foamed particles. A foamed molded product of polylactic acid resin having a desired shape excellent in fusion property and heat resistance by fusing the foamed particles to each other by their foaming pressure and increasing the crystallinity of the polylactic acid resin. Obtainable.

なお、金型内に充填したポリ乳酸系樹脂発泡粒子の加熱媒体としては、特に限定されず、水蒸気の他に、熱風などが挙げられる。水蒸気の圧力は、低いと、ポリ乳酸系樹脂発泡粒子の結晶化度を充分に上昇させることができず、得られるポリ乳酸系樹脂発泡成形体の耐熱性が低下することがある一方、高いと、ポリ乳酸系樹脂発泡粒子の温度上昇が急激なものとなり、ポリ乳酸系樹脂発泡粒子の結晶化度の上昇がポリ乳酸系樹脂発泡粒子の溶融速度に追いつかず、ポリ乳酸系樹脂発泡粒子が溶けてしまい、発泡圧が不足して、ポリ乳酸系樹脂発泡粒子を発泡させて得られる発泡粒子同士の融着性が低下し或いは得られるポリ乳酸系樹脂発泡成形体に収縮が生じることがあるので、適宜調整される。   In addition, it does not specifically limit as a heating medium of the polylactic acid-type resin expanded particle with which it filled in the metal mold | die, Hot air etc. are mentioned other than water vapor | steam. If the water vapor pressure is low, the degree of crystallinity of the polylactic acid-based resin expanded particles cannot be sufficiently increased, and the heat resistance of the resulting polylactic acid-based resin foamed molded product may decrease, whereas if the pressure is high As a result, the temperature rise of the polylactic acid resin expanded particles becomes abrupt, and the increase in crystallinity of the polylactic acid resin expanded particles cannot keep up with the melting rate of the polylactic acid resin expanded particles, so that the polylactic acid resin expanded particles melt. Therefore, the foaming pressure is insufficient, and the fusion property between the foamed particles obtained by foaming the polylactic acid-based resin foamed particles may be lowered, or the resulting polylactic acid-based resin foamed molded product may shrink. , Adjusted as appropriate.

又、得られたポリ乳酸系樹脂発泡成形体の融着率は、４０％以上が好ましく、５０％以上がより好ましく、６０％以上が特に好ましい。なお、ポリ乳酸系樹脂発泡成形体の融着率は、下記の要領で測定されたものをいう。先ず、ポリ乳酸系樹脂発泡成形体を折り曲げて所定箇所から切断する。そして、ポリ乳酸系樹脂発泡成形体の切断面に露出している発泡粒子の全粒子数Ｎ1 を目視により数えると共に、材料破壊した発泡粒子、即ち、分割された発泡粒子の粒子数Ｎ2 を目視により数え、下記式に基づいて融着率を算出することができる。
融着率（％）＝１００×材料破壊した発泡粒子の粒子数Ｎ2 ／発泡粒子の全粒子数Ｎ1 Further, the fusion rate of the obtained polylactic acid resin foamed molded article is preferably 40% or more, more preferably 50% or more, and particularly preferably 60% or more. In addition, the fusion rate of a polylactic acid-type resin foaming molding means what was measured in the following way. First, the polylactic acid resin foamed molded body is bent and cut from a predetermined location. The total number of foam particles N 1 exposed on the cut surface of the polylactic acid resin foam molded article is visually counted, and the foamed particles whose material is broken, that is, the number N 2 of the divided foam particles is calculated. It can be counted visually and the fusion rate can be calculated based on the following formula.
Fusing rate (%) = 100 × number of particles of expanded foam particles N 2 / total number of expanded particles N 1

更に、上記ポリ乳酸系樹脂発泡粒子に更に不活性ガスを常温にて含浸させて、ポリ乳酸系樹脂発泡粒子の発泡力を向上させてもよい。このようにポリ乳酸系樹脂発泡粒子の発泡力を向上させることにより、型内発泡成形時におけるポリ乳酸系樹脂発泡粒子を発泡させて得られる発泡粒子同士の融着性が向上し、得られるポリ乳酸系樹脂発泡成形体は更に優れた機械的強度を有する。なお、上記不活性ガスとしては、例えば、二酸化炭素、窒素、ヘリウムなどが挙げられる。   Furthermore, the foaming power of the polylactic acid resin expanded particles may be improved by impregnating the polylactic acid resin expanded particles with an inert gas at room temperature. Thus, by improving the foaming power of the polylactic acid-based resin foamed particles, the fusion property between the foamed particles obtained by foaming the polylactic acid-based resin foamed particles at the time of in-mold foam molding is improved. The lactic acid-based resin foam molded article has further excellent mechanical strength. Examples of the inert gas include carbon dioxide, nitrogen, and helium.

本発明の型内発泡成形用ポリ乳酸系樹脂発泡粒子の製造方法は、ポリ乳酸系樹脂と、エポキシ基を有するアクリル・スチレン系化合物とを押出機に供給して発泡剤の存在下にて溶融混練し押出発泡して押出発泡体を製造し、この押出発泡体を粒子状に切断して発泡粒子を製造する型内発泡成形用ポリ乳酸系樹脂発泡粒子の製造方法において、上記ポリ乳酸系樹脂が、その構成モノマー成分としてＤ体及びＬ体の双方の光学異性体を含有し且つＤ体又はＬ体のうちの少ない方の光学異性体の含有量が５モル％未満であるか、或いは、構成モノマー成分としてＤ体又はＬ体のうちの何れか一方の光学異性体のみを含有していると共に、ポリ乳酸系樹脂発泡粒子の連続気泡率が３０％未満で且つポリ乳酸系樹脂発泡粒子の結晶化度が３０％未満となるように調整することを特徴とするので、ポリ乳酸系樹脂と、エポキシ基を有するアクリル・スチレン系化合物とを押出機内において反応させて、ポリ乳酸系樹脂の動的粘弾性を改質し、ポリ乳酸系樹脂の結晶化度を低く抑えた状態に押出発泡させていると共に、ポリ乳酸系樹脂の脆性を改善しており、よって、本発明のポリ乳酸系樹脂発泡粒子の製造方法にて得られたポリ乳酸系樹脂発泡粒子を用いて型内発泡成形することによって、融着性、耐熱性及び耐衝撃性に優れたポリ乳酸系樹脂発泡成形体を得ることができる。   The method for producing foamed polylactic acid resin particles for in-mold foam molding of the present invention is to supply a polylactic acid resin and an acrylic / styrene compound having an epoxy group to an extruder and melt in the presence of a foaming agent. In the method for producing in-mold foamed polylactic acid resin foamed particles, the above polylactic acid resin is produced by kneading and extrusion foaming to produce an extruded foam, and then cutting the extruded foam into particles to produce foamed particles. Which contains both D-form and L-form optical isomers as constituent monomer components and the content of the lesser of the D-form and L-form is less than 5 mol%, or Containing only one optical isomer of D-form or L-form as a constituent monomer component, and the open cell ratio of the polylactic acid-based resin expanded particles is less than 30%, and the polylactic acid-based resin expanded particles Crystallinity is less than 30% The polylactic acid resin is reacted with an acrylic / styrene compound having an epoxy group in the extruder to modify the dynamic viscoelasticity of the polylactic acid resin. The lactic acid resin is extruded and foamed in a state where the crystallinity of the resin is kept low, and the brittleness of the polylactic acid resin is improved. Therefore, the polylactic acid resin foam particles of the present invention can be obtained. A polylactic acid-based resin foam molded article excellent in fusion property, heat resistance and impact resistance can be obtained by in-mold foam molding using the expanded polylactic acid resin particles.

そして、本発明の型内発泡成形用ポリ乳酸系樹脂発泡粒子の製造方法では、ポリ乳酸系樹脂として、構成モノマー成分としてＤ体及びＬ体の双方の光学異性体を含有し且つＤ体又はＬ体のうちの少ない方の光学異性体の含有量が５モル％未満であるポリ乳酸系樹脂か、或いは、構成モノマー成分としてＤ体又はＬ体のうちの何れか一方の光学異性体のみを含有しているポリ乳酸系樹脂を用いていることから、得られるポリ乳酸系樹脂発泡粒子は、その結晶化性が高くて耐熱性に優れている。   And in the manufacturing method of the polylactic acid-type resin expanded particle for in-mold foam-molding of this invention, as a polylactic acid-type resin, it contains the optical isomer of both D body and L body as a structural monomer component, and D body or L body. A polylactic acid-based resin having a content of less than 5 mol% of the optical isomer of the isomer, or only one of the optical isomers of the D isomer and the L isomer as a constituent monomer component Since the polylactic acid resin used is used, the resulting polylactic acid resin foamed particles have high crystallinity and excellent heat resistance.

更に、上記型内発泡成形用ポリ乳酸系樹脂発泡粒子の製造方法では、結晶性が高いポリ乳酸系樹脂をエポキシ基を有するアクリル・スチレン系化合物によって改質して押出発泡に適したものとし、押出発泡によってポリ乳酸系樹脂を発泡させており、従来のようにポリ乳酸系樹脂粒子を一旦、作製し、このポリ乳酸系樹脂粒子に発泡剤を含浸させて予備発泡させる場合と異なり、粒子状にしてから熱を加えることはなく、よって、ポリ乳酸系樹脂発泡粒子の結晶化度の上昇を防止し、得られるポリ乳酸系樹脂発泡粒子の融着性を良好に維持することができる。   Furthermore, in the method for producing foamed polylactic acid resin particles for in-mold foam molding, a polylactic acid resin having high crystallinity is modified with an acrylic / styrene compound having an epoxy group and is suitable for extrusion foaming, Unlike the case where the polylactic acid resin is foamed by extrusion foaming, and the polylactic acid resin particles are once prepared and impregnated with a foaming agent in the conventional manner and then pre-foamed. Therefore, heat is not applied, and therefore, the increase in crystallinity of the polylactic acid-based resin expanded particles can be prevented, and the fusion property of the obtained polylactic acid-based resin expanded particles can be maintained well.

そして、上記型内発泡成形用ポリ乳酸系樹脂発泡粒子の製造方法で得られるポリ乳酸系樹脂発泡粒子は、その結晶化度が３０％未満となるように調整されていることから、型内発泡時における融着性に優れていると共に、この型内発泡時に加えられる熱によってポリ乳酸系樹脂粒子の結晶化度を、該ポリ乳酸系樹脂発泡粒子を発泡させて得られる発泡粒子同士の融着性を阻害させないように上昇させて、ポリ乳酸系樹脂発泡成形体に優れた耐熱性を付与することができ、よって、本発明のポリ乳酸系樹脂発泡粒子を用いて得られたポリ乳酸系樹脂発泡成形体は優れた耐熱性及び機械的強度を有する。   The polylactic acid resin foamed particles obtained by the above-described method for producing foamed polylactic acid resin for foam molding are adjusted so that the crystallinity thereof is less than 30%. In addition to excellent fusion at the time, the degree of crystallinity of the polylactic acid resin particles by the heat applied during in-mold foaming and the fusion of the foamed particles obtained by foaming the foamed polylactic acid resin particles The polylactic acid-based resin obtained by using the polylactic acid-based resin foamed particles of the present invention can be imparted with excellent heat resistance to the polylactic acid-based resin foamed molded article. The foamed molded article has excellent heat resistance and mechanical strength.

又、上記型内発泡成形用ポリ乳酸系樹脂発泡粒子の製造方法において、押出機に、気泡調整剤としてポリテトラフルオロエチレン粉末又はアクリル樹脂で変性されたポリテトラフルオロエチレン粉末を供給する場合には、これら気泡調整剤は押出機内において繊維状となり、この繊維状のポリテトラフルオロエチレンは、エポキシ基を有するアクリル・スチレン系化合物によって改質されたポリ乳酸系樹脂の分子鎖に絡みついて、エポキシ基を有するアクリル・スチレン系化合物によるポリ乳酸系樹脂の動的粘弾性の改質を一層促進し、ポリ乳酸系樹脂の押出発泡性をより向上させて、ポリ乳酸系樹脂の結晶化度を抑えた状態に更に安定的に押出発泡させることができると共に、ポリ乳酸系樹脂発泡粒子の連続気泡率も低いものとすることができ、そして、このようなポリ乳酸系樹脂発泡粒子を用いることによって、耐熱性及び機械的強度に優れたポリ乳酸系樹脂発泡成形体をより確実に得ることができる。   Also, in the above-described method for producing foamed polylactic acid-based resin particles for in-mold foam molding, when supplying polytetrafluoroethylene powder or polytetrafluoroethylene powder modified with acrylic resin as a foam regulator to the extruder, These bubble regulators become fibrous in the extruder, and the fibrous polytetrafluoroethylene is entangled with the molecular chain of the polylactic acid resin modified with the acrylic / styrene compound having an epoxy group, Improved the dynamic viscoelasticity modification of polylactic acid resin with acrylic / styrene compound containing styrene, further improved the extrusion foamability of polylactic acid resin, and reduced the crystallinity of polylactic acid resin It can be more stably extruded and foamed in a state, and the open cell ratio of the polylactic acid resin foamed particles should be low. Come, and, by using such a polylactic acid-based resin foamed particles, it is possible to obtain a polylactic acid resin expansion molding having excellent heat resistance and mechanical strength more reliably.

本発明においてポリ乳酸系樹脂発泡粒子の嵩密度及びポリ乳酸系樹脂発泡成形体の見掛け密度は下記の要領によって測定されたものをいう。   In the present invention, the bulk density of the polylactic acid-based resin expanded particles and the apparent density of the polylactic acid-based resin expanded molded product are those measured according to the following procedure.

（ポリ乳酸系樹脂発泡粒子の嵩密度）
ポリ乳酸系樹脂発泡粒子の嵩密度は、ＪＩＳ Ｋ６９１１：１９９５年「熱硬化性プラスチック一般試験方法」に準拠して測定されたものをいう。即ち、ＪＩＳ Ｋ６９１１に準拠した見掛け密度測定器を用いて測定し、下記式に基づいてポリ乳酸系樹脂発泡粒子の嵩密度を測定した。 (Bulk density of polylactic acid resin foamed particles)
The bulk density of the polylactic acid-based resin expanded particles refers to that measured according to JIS K6911: 1995 “General Test Method for Thermosetting Plastics”. That is, it measured using the apparent density measuring device based on JISK6911, and measured the bulk density of the polylactic acid-type resin expanded particle based on the following formula.

ポリ乳酸系樹脂発泡粒子の嵩密度（ｇ／ｃｍ3 ）
＝〔試料を入れたメスシリンダーの質量（ｇ）−メスシリンダーの質量（ｇ）〕
／〔メスシリンダーの容量（ｃｍ3 ）〕 Bulk density (g / cm 3 ) of foamed polylactic acid resin
= [Mass of measuring cylinder with sample (g) -Mass of measuring cylinder (g)]
/ [Capacity of measuring cylinder (cm 3 )]

（ポリ乳酸系樹脂発泡成形体の見掛け密度）
ポリ乳酸系樹脂発泡成形体の見掛け密度は、ＪＩＳ Ｋ６７６７：１９９９「発泡プラスチック及びゴム−見掛け密度の測定」に記載の方法で測定されたものをいう。 (Apparent density of polylactic acid resin foam molding)
The apparent density of the polylactic acid-based resin foamed molded product refers to that measured by the method described in JIS K6767: 1999 “Measurement of foamed plastic and rubber-apparent density”.

（実施例１）
一段目となる口径５０ｍｍの単軸押出機と二段目となる口径６５ｍｍの単軸押出機とを接続管を介して接続してなるタンデム型の押出機を用意した。 Example 1
A tandem type extruder in which a single-screw extruder having a diameter of 50 mm serving as the first stage and a single-screw extruder having a diameter of 65 mm serving as the second stage were connected via a connecting pipe was prepared.

そして、上記タンデム型の押出機の一段目の押出機に、結晶性のポリ乳酸系樹脂（島津製作所社製 商品名「ＬＡＣＴＹ ９０３０Ａ」、融点：１７１．０℃、Ｄ体比率：１．６モル％、Ｌ体比率：９８．４モル％）１００重量部、エポキシ基を有するアクリル・スチレン系化合物とポリ乳酸系樹脂とのマスターバッチ２．０重量部、及び、気泡調整剤としてポリテトラフルオロエチレン粉末（旭硝子社製 商品名「フルオンＬ１６９Ｊ」）０．１重量部を供給して溶融混練した。なお、エポキシ基を有するアクリル・スチレン系化合物とポリ乳酸系樹脂とのマスターバッチは、エポキシ基を有するアクリル・スチレン系化合物（東亞合成社製 商品名「ＡＲＵＦＯＮ ＵＧ−４０３０」、重量平均分子量：１１０００、エポキシ価：１．８ｍｍｏｌ／ｇ）３０重量％とポリ乳酸系樹脂（三井化学社製 商品名「ＬＡＣＥＡ Ｈ−１００」）７０重量％とから構成されていた。   Then, a crystalline polylactic acid resin (trade name “LACTY 9030A” manufactured by Shimadzu Corporation, melting point: 171.0 ° C., D-form ratio: 1.6 mol) %, L-form ratio: 98.4 mol%) 100 parts by weight, 2.0 parts by weight of a master batch of an acrylic / styrene compound having an epoxy group and a polylactic acid resin, and polytetrafluoroethylene as a bubble regulator 0.1 parts by weight of powder (trade name “Fluon L169J” manufactured by Asahi Glass Co., Ltd.) was supplied and melt-kneaded. The master batch of an acrylic / styrene compound having an epoxy group and a polylactic acid resin is an acrylic / styrene compound having an epoxy group (trade name “ARUFON UG-4030” manufactured by Toagosei Co., Ltd., weight average molecular weight: 11000. , Epoxy value: 1.8 mmol / g) and 30% by weight of polylactic acid resin (trade name “LACEA H-100” manufactured by Mitsui Chemicals, Inc.).

なお、第一押出機は、その供給部を１９０℃に、圧縮部を２３０℃に、発泡剤注入・混合部を２２０℃に、計量部を１９０℃に、ヘッド部を２００℃に保持した。   The first extruder was maintained at 190 ° C. for the supply unit, 230 ° C. for the compression unit, 220 ° C. for the blowing agent injection / mixing unit, 190 ° C. for the metering unit, and 200 ° C. for the head unit.

続いて、第一押出機の途中から、イソブタン３５重量％及びノルマルブタン６５重量％からなるブタンをポリ乳酸系樹脂１００重量部に対して０．７重量部となるように溶融状態のポリ乳酸系樹脂に圧入して、ポリ乳酸系樹脂中に均一に分散させた。   Subsequently, in the middle of the first extruder, a polylactic acid-based polylactic acid in a molten state so that butane comprising 35% by weight of isobutane and 65% by weight of normal butane is 0.7 parts by weight with respect to 100 parts by weight of the polylactic acid-based resin. It was press-fitted into the resin and uniformly dispersed in the polylactic acid resin.

しかる後、溶融状態のポリ乳酸系樹脂を一段目の押出機から接続管を介して二段目の押出機に連続的に供給した。溶融状態のポリ乳酸系樹脂を二段目の押出機にて樹脂温度２００℃に冷却した後、二段目の押出機の先端に取り付けたマルチノズル金型の各ノズルから剪断速度５６５９ｓｅｃ-1で押出発泡させてストランド状のポリ乳酸系樹脂押出発泡体を製造した。 Thereafter, the molten polylactic acid-based resin was continuously supplied from the first-stage extruder to the second-stage extruder via a connecting pipe. After cooling to a resin temperature of 200 ° C. The polylactic acid-based resin in a molten state by a two-stage extruder, at a shear rate 5659Sec -1 from the nozzles of the multi-nozzle die attached to the tip of the extruder in the second stage Extruded and foamed to produce a strand-like polylactic acid resin extruded foam.

続いて、ストランド状のポリ乳酸系樹脂押出発泡体を、マルチノズル金型の各ノズル先端から６０ｃｍの距離に亘って空冷により冷却し、続いて、ストランド状のポリ乳酸系樹脂押出発泡体を２ｍの距離に亘って冷却水槽内の水面上に浮かせて冷却した。なお、冷却水槽内の水温は、３０℃であった。   Subsequently, the strand-shaped polylactic acid-based resin extruded foam was cooled by air cooling over a distance of 60 cm from each nozzle tip of the multi-nozzle mold, and then the strand-shaped polylactic acid-based resin extruded foam was 2 m. Over the water surface in the cooling water tank and cooled. In addition, the water temperature in a cooling water tank was 30 degreeC.

なお、マルチノズル金型は、出口直径が１．０ｍｍのノズルが１５個、配設されており、ランド部の長さは５ｍｍであり、２００℃に保持されていた。又、マルチノズル金型のノズルから押出発泡させた際の樹脂温度は、二段目の押出機の先端部と金型との間にブレーカープレートを挿入し、このブレーカープレートの中心部に熱電対を挿入することによって測定した。   The multi-nozzle mold was provided with 15 nozzles having an exit diameter of 1.0 mm, the land portion had a length of 5 mm, and was maintained at 200 ° C. The resin temperature when extrusion foaming from the nozzle of the multi-nozzle mold is such that a breaker plate is inserted between the tip of the second stage extruder and the mold, and a thermocouple is placed in the center of the breaker plate. Was measured by inserting.

そして、ストランド状のポリ乳酸系樹脂押出発泡体を充分に水切りした後、このポリ乳酸系樹脂押出発泡体をファンカッタ式のペレタイザーを用いて２．２ｍｍ毎に円柱状に切断してポリ乳酸系樹脂発泡粒子を得た。なお、得られたポリ乳酸系樹脂発泡粒子は、その嵩密度が０．２０ｇ／ｃｍ3 で、粒径が１．７〜２．２ｍｍで、結晶化度は２１．１％で、連続気泡率は２５．３％であった。 Then, after sufficiently draining the strand-like polylactic acid resin extruded foam, the polylactic acid resin extruded foam is cut into a cylindrical shape every 2.2 mm using a fan cutter type pelletizer. Resin foam particles were obtained. The obtained polylactic acid-based resin expanded particles had a bulk density of 0.20 g / cm 3 , a particle size of 1.7 to 2.2 mm, a crystallinity of 21.1%, and an open cell ratio. Was 25.3%.

次に、上記ポリ乳酸系樹脂発泡粒子を密閉容器内に入れ、この密閉容器内に二酸化炭素を０．４９ＭＰａの圧力にて圧入して常温にて２４時間に亘って放置してポリ乳酸系樹脂発泡粒子に二酸化炭素を含浸させた。   Next, the polylactic acid-based resin expanded particles are put in a sealed container, and carbon dioxide is pressed into the sealed container at a pressure of 0.49 MPa and left at room temperature for 24 hours to leave the polylactic acid-based resin. The expanded particles were impregnated with carbon dioxide.

続いて、上記ポリ乳酸系樹脂発泡粒子を金型内に充填して型締めし、この金型内にゲージ圧０．０６ＭＰａの水蒸気を２０秒間に亘って供給して、ポリ乳酸系樹脂発泡粒子を加熱、発泡させて、このポリ乳酸系樹脂発泡粒子を発泡させて得られる発泡粒子同士を融着一体化させ、更に、この状態にて１２０秒間に亘って保温した後に水冷して、縦３００ｍｍ×横４００ｍｍ×高さ２０ｍｍの直方体形状のポリ乳酸系樹脂発泡成形体を得た。なお、得られたポリ乳酸系樹脂発泡成形体は、その見掛け密度が０．２０ｇ／ｃｍ3 で、融着率は６０％であった。 Subsequently, the polylactic acid-based resin expanded particles are filled in a mold and clamped, and water vapor with a gauge pressure of 0.06 MPa is supplied into the mold for 20 seconds. The foamed particles obtained by foaming and foaming the polylactic acid resin foamed particles are fused and integrated with each other, and further kept warm in this state for 120 seconds, and then water-cooled to 300 mm in length. A rectangular parallelepiped polylactic acid-based resin foam molded article having a width of 400 mm and a height of 20 mm was obtained. The resulting polylactic acid resin foamed molded article had an apparent density of 0.20 g / cm 3 and a fusion rate of 60%.

又、第一押出機への発泡剤の圧入をしなかったこと、ペレタイザーを用いて０．７〜１．０ｍｍ毎に円柱状に切断したこと以外は、上記と同様の要領で測定用ポリ乳酸系樹脂粒子を得た。   In addition, polylactic acid for measurement was measured in the same manner as described above except that the foaming agent was not pressed into the first extruder and was cut into a cylindrical shape every 0.7 to 1.0 mm using a pelletizer. System resin particles were obtained.

得られた測定用ポリ乳酸系樹脂粒子を用いて動的粘弾性測定を行ったところ、貯蔵弾性率曲線と損失弾性率曲線との交点における温度Ｔは、１３８．１℃であった。又、測定用ポリ乳酸系樹脂粒子を構成しているポリ乳酸系樹脂の融点（ｍｐ）を測定したところ、１７１．１℃であった。   When dynamic viscoelasticity measurement was performed using the obtained polylactic acid resin particles for measurement, the temperature T at the intersection of the storage elastic modulus curve and the loss elastic modulus curve was 138.1 ° C. Further, the melting point (mp) of the polylactic acid resin constituting the polylactic acid resin particles for measurement was measured and found to be 171.1 ° C.

（実施例２）
エポキシ基を有するアクリル・スチレン系化合物とポリ乳酸系樹脂とのマスターバッチを２．０重量部の代わりに３．０重量部としたこと以外は実施例１と同様にしてポリ乳酸系樹脂発泡粒子を得た。なお、得られたポリ乳酸系樹脂発泡粒子は、その嵩密度が０．２０ｇ／ｃｍ3 で、粒径が１．７〜２．２ｍｍで、結晶化度は２５．３％で、連続気泡率は２１．１％であった。 (Example 2)
Polylactic acid resin expanded particles in the same manner as in Example 1 except that the master batch of the acrylic / styrene compound having an epoxy group and the polylactic acid resin was changed to 3.0 parts by weight instead of 2.0 parts by weight. Got. The obtained polylactic acid-based resin foamed particles had a bulk density of 0.20 g / cm 3 , a particle size of 1.7 to 2.2 mm, a crystallinity of 25.3%, and an open cell ratio. Was 21.1%.

得られたポリ乳酸系樹脂発泡粒子を用いて実施例１と同様の要領でポリ乳酸系樹脂発泡成形体を得た。なお、得られたポリ乳酸系樹脂発泡成形体は、その見掛け密度が０．２０ｇ／ｃｍ3 で、融着率は７０％であった。 Using the obtained polylactic acid resin foamed particles, a polylactic acid resin foam molded article was obtained in the same manner as in Example 1. The obtained polylactic acid resin foamed molded article had an apparent density of 0.20 g / cm 3 and a fusion rate of 70%.

又、第一押出機への発泡剤の圧入をしなかったこと、ペレタイザーを用いて０．７〜１．０ｍｍ毎に円柱状に切断したこと以外は、上記と同様の要領で測定用ポリ乳酸系樹脂粒子を製造し、この測定用ポリ乳酸系樹脂粒子を用いて動的粘弾性測定を行ったところ、貯蔵弾性率曲線と損失弾性率曲線との交点における温度Ｔは、１４０．６℃であった。又、測定用ポリ乳酸系樹脂粒子を構成しているポリ乳酸系樹脂の融点（ｍｐ）を測定したところ、１７１．２℃であった。   In addition, polylactic acid for measurement was measured in the same manner as described above except that the foaming agent was not pressed into the first extruder and was cut into a cylindrical shape every 0.7 to 1.0 mm using a pelletizer. When the system resin particles were produced and the dynamic viscoelasticity measurement was performed using the polylactic acid resin particles for measurement, the temperature T at the intersection of the storage elastic modulus curve and the loss elastic modulus curve was 140.6 ° C. there were. Further, the melting point (mp) of the polylactic acid resin constituting the polylactic acid resin particles for measurement was measured and found to be 171.2 ° C.

（実施例３）
エポキシ基を有するアクリル・スチレン系化合物とポリ乳酸系樹脂とのマスターバッチとして、エポキシ基を有するアクリル・スチレン系化合物（東亜合成社製 商品名「ＡＲＵＦＯＮ ＵＧ−４０４０」）３０重量％と、ポリ乳酸系樹脂（三井化学社製 商品名「ＬＡＣＥＡ Ｈ−１００」）７０重量％とから構成されているマスターバッチを用いたこと以外は実施例１と同様にしてポリ乳酸系樹脂発泡粒子を得た。なお、得られたポリ乳酸系樹脂発泡粒子は、その嵩密度が０．２０ｇ／ｃｍ3 で、粒径が１．７〜２．２ｍｍで、結晶化度は２１．６％で、連続気泡率は１９．８％であった。 (Example 3)
As a master batch of an acrylic / styrene compound having an epoxy group and a polylactic acid resin, 30% by weight of an acrylic / styrene compound (trade name “ARUFON UG-4040” manufactured by Toagosei Co., Ltd.) having an epoxy group and polylactic acid Polylactic acid-based resin expanded particles were obtained in the same manner as in Example 1 except that a master batch composed of 70% by weight of a resin based on a product (trade name “LACEA H-100” manufactured by Mitsui Chemicals, Inc.) was used. The obtained polylactic acid-based resin expanded particles have a bulk density of 0.20 g / cm 3 , a particle size of 1.7 to 2.2 mm, a crystallinity of 21.6%, and an open cell ratio. Was 19.8%.

得られたポリ乳酸系樹脂発泡粒子を用いて実施例１と同様の要領でポリ乳酸系樹脂発泡成形体を得た。なお、得られたポリ乳酸系樹脂発泡成形体は、その見掛け密度が０．２０ｇ／ｃｍ3 で、融着率は７０％であった。 A polylactic acid resin foam molded article was obtained in the same manner as in Example 1 using the obtained polylactic acid resin foamed particles. The resulting polylactic acid resin foamed molded article had an apparent density of 0.20 g / cm 3 and a fusion rate of 70%.

又、第一押出機への発泡剤の圧入をしなかったこと、ペレタイザーを用いて０．７〜１．０ｍｍ毎に円柱状に切断したこと以外は、上記と同様の要領で測定用ポリ乳酸系樹脂粒子を製造し、この測定用ポリ乳酸系樹脂粒子を用いて動的粘弾性測定を行ったところ、貯蔵弾性率曲線と損失弾性率曲線との交点における温度Ｔは、１３９．３℃であった。又、測定用ポリ乳酸系樹脂粒子を構成しているポリ乳酸系樹脂の融点（ｍｐ）を測定したところ、１７１．１℃あった。   In addition, polylactic acid for measurement was measured in the same manner as described above except that the foaming agent was not pressed into the first extruder and was cut into a cylindrical shape every 0.7 to 1.0 mm using a pelletizer. When the dynamic viscoelasticity measurement was performed using the polylactic acid resin particles for measurement, the temperature T at the intersection of the storage elastic modulus curve and the loss elastic modulus curve was 139.3 ° C. there were. Further, when the melting point (mp) of the polylactic acid resin constituting the polylactic acid resin particles for measurement was measured, it was 171.1 ° C.

（実施例４）
ポリ乳酸系樹脂として、結晶性のポリ乳酸系樹脂（ユニチカ社製 商品名「ＴＥＲＲＡＭＡＣ ＴＥ−４０００」、融点：１７０．３℃、Ｄ体比率：１．６モル％、Ｌ体比率：９８．４モル％）１００重量部を用いたこと以外は実施例２と同様にしてポリ乳酸系樹脂発泡粒子を得た。なお、得られたポリ乳酸系樹脂発泡粒子は、その嵩密度が０．２０ｇ／ｃｍ3 で、粒径が１．７〜２．２ｍｍで、結晶化度は２５．７％で、連続気泡率は２１．８％であった。 Example 4
As a polylactic acid resin, a crystalline polylactic acid resin (trade name “TERRAMAC TE-4000” manufactured by Unitika Ltd.), melting point: 170.3 ° C., D-form ratio: 1.6 mol%, L-form ratio: 98.4 Mol%) Polylactic acid resin expanded particles were obtained in the same manner as in Example 2 except that 100 parts by weight were used. The obtained polylactic acid-based resin expanded particles had a bulk density of 0.20 g / cm 3 , a particle size of 1.7 to 2.2 mm, a crystallinity of 25.7%, and an open cell ratio. Was 21.8%.

得られたポリ乳酸系樹脂発泡粒子を用いて実施例１と同様の要領でポリ乳酸系樹脂発泡成形体を得た。なお、得られたポリ乳酸系樹脂発泡成形体は、その見掛け密度が０．２０ｇ／ｃｍ3 で、融着率は７０％であった。 A polylactic acid resin foam molded article was obtained in the same manner as in Example 1 using the obtained polylactic acid resin foamed particles. The resulting polylactic acid resin foamed molded article had an apparent density of 0.20 g / cm 3 and a fusion rate of 70%.

又、第一押出機への発泡剤の圧入をしなかったこと、ペレタイザーを用いて０．７〜１．０ｍｍ毎に円柱状に切断したこと以外は、上記と同様の要領で測定用ポリ乳酸系樹脂粒子を製造し、この測定用ポリ乳酸系樹脂粒子を用いて動的粘弾性測定を行ったところ、貯蔵弾性率曲線と損失弾性率曲線との交点における温度Ｔは、１４０．１℃であった。又、測定用ポリ乳酸系樹脂粒子を構成しているポリ乳酸系樹脂の融点（ｍｐ）を測定したところ、１７０．５℃であった。   In addition, polylactic acid for measurement was measured in the same manner as described above except that the foaming agent was not pressed into the first extruder and was cut into a cylindrical shape every 0.7 to 1.0 mm using a pelletizer. When the dynamic viscoelasticity measurement was performed using the polylactic acid resin particles for measurement, the temperature T at the intersection of the storage elastic modulus curve and the loss elastic modulus curve was 140.1 ° C. there were. Further, when the melting point (mp) of the polylactic acid resin constituting the polylactic acid resin particles for measurement was measured, it was 170.5 ° C.

（比較例１）
エポキシ基を有するアクリル・スチレン系化合物とポリ乳酸系樹脂とのマスターバッチを用いなかったこと以外は実施例１と同様の要領でポリ乳酸系樹脂発泡粒子を得た。しかしながら、押出機から押出発泡させて得られたストランド状のポリ乳酸系樹脂押出発泡体に、破泡に伴うガスの抜け穴が断続的に発生し、ポリ乳酸系樹脂発泡粒子を安定的に製造することができなかった。 (Comparative Example 1)
Polylactic acid resin expanded particles were obtained in the same manner as in Example 1 except that a master batch of an acrylic / styrene compound having an epoxy group and a polylactic acid resin was not used. However, in the strand-like polylactic acid resin extruded foam obtained by extrusion foaming from an extruder, gas pits are generated intermittently due to foam breakage, and polylactic acid resin expanded particles are stably produced. I couldn't.

又、第一押出機への発泡剤の圧入をしなかったこと、ペレタイザーを用いて０．７〜１．０ｍｍ毎に円柱状に切断したこと以外は、上記と同様の要領で測定用ポリ乳酸系樹脂粒子を製造し、この測定用ポリ乳酸系樹脂粒子を用いて動的粘弾性測定を行ったところ、貯蔵弾性率曲線と損失弾性率曲線との交点における温度Ｔは、１１８．２℃であった。又、測定用ポリ乳酸系樹脂粒子を構成しているポリ乳酸系樹脂の融点（ｍｐ）を測定したところ、１７１．０℃であった。   In addition, polylactic acid for measurement was measured in the same manner as described above except that the foaming agent was not pressed into the first extruder and was cut into a cylindrical shape every 0.7 to 1.0 mm using a pelletizer. When the dynamic viscoelasticity measurement was performed using the polylactic acid resin particles for measurement, the temperature T at the intersection of the storage elastic modulus curve and the loss elastic modulus curve was 118.2 ° C. there were. The melting point (mp) of the polylactic acid resin constituting the measurement polylactic acid resin particles was measured and found to be 171.0 ° C.

（比較例２）
エポキシ基を有するアクリル・スチレン系化合物とポリ乳酸系樹脂とのマスターバッチを２．０重量部の代わりに１．０重量部としたこと以外は実施例１と同様にしてポリ乳酸系樹脂発泡粒子を得た。なお、得られたポリ乳酸系樹脂発泡粒子は、その嵩密度が０．２０ｇ／ｃｍ3 で、粒径が１．７〜２．２ｍｍで、結晶化度は１９．０％で、連続気泡率は３５．０％であった。 (Comparative Example 2)
Polylactic acid resin expanded particles in the same manner as in Example 1 except that the master batch of the acrylic / styrene compound having an epoxy group and the polylactic acid resin was changed to 1.0 part by weight instead of 2.0 parts by weight. Got. The obtained polylactic acid-based resin expanded particles had a bulk density of 0.20 g / cm 3 , a particle size of 1.7 to 2.2 mm, a crystallinity of 19.0%, and an open cell ratio. Was 35.0%.

得られたポリ乳酸系樹脂発泡粒子を用いて実施例１と同様の要領でポリ乳酸系樹脂発泡成形体を得た。なお、得られたポリ乳酸系樹脂発泡成形体は、その見掛け密度が０．２０ｇ／ｃｍ3 で、融着率は１０％であった。 A polylactic acid resin foam molded article was obtained in the same manner as in Example 1 using the obtained polylactic acid resin foamed particles. The resulting polylactic acid resin foamed molded article had an apparent density of 0.20 g / cm 3 and a fusion rate of 10%.

又、第一押出機への発泡剤の圧入をしなかったこと、ペレタイザーを用いて０．７〜１．０ｍｍ毎に円柱状に切断したこと以外は、上記と同様の要領で測定用ポリ乳酸系樹脂粒子を製造し、この測定用ポリ乳酸系樹脂粒子を用いて動的粘弾性測定を行ったところ、貯蔵弾性率曲線と損失弾性率曲線との交点における温度Ｔは、１２９．０℃であった。又、測定用ポリ乳酸系樹脂粒子を構成しているポリ乳酸系樹脂の融点（ｍｐ）を測定したところ、１７１．０℃であった。   In addition, polylactic acid for measurement was measured in the same manner as described above except that the foaming agent was not pressed into the first extruder and was cut into a cylindrical shape every 0.7 to 1.0 mm using a pelletizer. When the dynamic viscoelasticity measurement was performed using the polylactic acid resin particles for measurement, the temperature T at the intersection of the storage elastic modulus curve and the loss elastic modulus curve was 129.0 ° C. there were. The melting point (mp) of the polylactic acid resin constituting the measurement polylactic acid resin particles was measured and found to be 171.0 ° C.

（比較例３）
ストランド状のポリ乳酸系樹脂押出発泡体を、水面上に浮かせて冷却する代わりに、ポリテトラフルオロエチレンで被覆された鉄製冷却板上に接触させることによって冷却したこと以外は実施例１と同様にしてポリ乳酸系樹脂発泡粒子を得た。なお、得られたポリ乳酸系樹脂発泡粒子は、その嵩密度が０．２０ｇ／ｃｍ3 で、粒径が１．７〜２．２ｍｍで、結晶化度は３１．２％で、連続気泡率は２０．９％であった。 (Comparative Example 3)
Except that the extruded polylactic acid resin foam in the form of a strand was cooled by bringing it into contact with an iron cold plate coated with polytetrafluoroethylene instead of floating on the water surface and cooling, the same as in Example 1. Thus, polylactic acid resin expanded particles were obtained. The obtained polylactic acid-based resin expanded particles had a bulk density of 0.20 g / cm 3 , a particle size of 1.7 to 2.2 mm, a crystallinity of 31.2%, and an open cell ratio. Was 20.9%.

得られたポリ乳酸系樹脂発泡粒子を用いて実施例１と同様の要領でポリ乳酸系樹脂発泡成形体を得た。なお、得られたポリ乳酸系樹脂発泡成形体は、その見掛け密度が０．２０ｇ／ｃｍ3 で、融着率は０％であった。 A polylactic acid resin foam molded article was obtained in the same manner as in Example 1 using the obtained polylactic acid resin foamed particles. The resulting polylactic acid resin foamed molded article had an apparent density of 0.20 g / cm 3 and a fusion rate of 0%.

Figure 2007169394
Figure 2007169394

Claims (6)

ポリ乳酸系樹脂と、エポキシ基を有するアクリル・スチレン系化合物とを押出機に供給して発泡剤の存在下にて溶融混練し押出発泡して押出発泡体を製造し、この押出発泡体を粒子状に切断して発泡粒子を製造する型内発泡成形用ポリ乳酸系樹脂発泡粒子の製造方法において、上記ポリ乳酸系樹脂が、その構成モノマー成分としてＤ体及びＬ体の双方の光学異性体を含有し且つＤ体又はＬ体のうちの少ない方の光学異性体の含有量が５モル％未満であるか、或いは、構成モノマー成分としてＤ体又はＬ体のうちの何れか一方の光学異性体のみを含有していると共に、ポリ乳酸系樹脂発泡粒子の連続気泡率が３０％未満で且つポリ乳酸系樹脂発泡粒子の結晶化度が３０％未満となるように調整することを特徴とする型内発泡成形用ポリ乳酸系樹脂発泡粒子の製造方法。 A polylactic acid resin and an acrylic / styrene compound having an epoxy group are supplied to an extruder, melt-kneaded in the presence of a foaming agent, extruded and foamed to produce an extruded foam, and the extruded foam is made into particles. In the method for producing foamed particles of in-mold foamed polylactic acid resin for producing foamed particles by cutting into foams, the polylactic acid-based resin has both D-form and L-form optical isomers as constituent monomer components thereof. And the content of the smaller optical isomer of D-form or L-form is less than 5 mol%, or any one of the D-form or L-form optical isomer as a constituent monomer component And a mold characterized in that the open cell ratio of the polylactic acid resin expanded particles is less than 30% and the crystallinity of the polylactic acid resin expanded particles is adjusted to be less than 30%. Polylactic acid tree for internal foam molding The method of manufacturing a sparkling particles. ポリ乳酸系樹脂発泡粒子を構成するポリ乳酸系樹脂が、その融点（ｍｐ）と、動的粘弾性測定にて得られた、貯蔵弾性率曲線と損失弾性率曲線との交点における温度Ｔとが下記式１を満たすように調整されていることを特徴とする請求項１に記載の型内発泡成形用ポリ乳酸系樹脂発泡粒子の製造方法。
（ポリ乳酸系樹脂の融点（ｍｐ）−４０℃）
≦（交点における温度Ｔ）≦ポリ乳酸系樹脂の融点（ｍｐ）・・・式１ The polylactic acid resin constituting the expanded polylactic acid resin particles has a melting point (mp) and a temperature T at the intersection of the storage elastic modulus curve and the loss elastic modulus curve obtained by dynamic viscoelasticity measurement. It adjusts so that following formula 1 may be satisfy | filled, The manufacturing method of the polylactic acid-type resin expanded particle for in-mold foam molding of Claim 1 characterized by the above-mentioned.
(Melting point of polylactic acid resin (mp) -40 ° C)
≦ (temperature T at the intersection) ≦ melting point of polylactic acid resin (mp) Formula 1 押出発泡体を粒子状に切断前又は切断後に水を用いて冷却することを特徴とする請求項１又は請求項２に記載の型内発泡成形用ポリ乳酸系樹脂発泡粒子の製造方法。 The method for producing foamed polylactic acid-based resin particles for in-mold foam molding according to claim 1 or 2, wherein the extruded foam is cooled with water before or after being cut into particles. 押出機に、気泡調整剤としてポリテトラフルオロエチレン粉末又はアクリル樹脂で変性されたポリテトラフルオロエチレン粉末を供給することを特徴とする請求項１乃至請求項３の何れか１項に記載の型内発泡成形用ポリ乳酸系樹脂発泡粒子の製造方法。 The mold according to any one of claims 1 to 3, wherein polytetrafluoroethylene powder or polytetrafluoroethylene powder modified with an acrylic resin is supplied as an air conditioner to the extruder. A method for producing foamed polylactic acid resin particles for foam molding. ポリ乳酸系樹脂１００重量部に対して気泡調整剤０．０１〜３重量部を供給することを特徴とする請求項４に記載の型内発泡成形用ポリ乳酸系樹脂発泡粒子の製造方法。 The method for producing foamed polylactic acid resin particles for in-mold foam molding according to claim 4, wherein 0.01 to 3 parts by weight of a cell regulator is supplied to 100 parts by weight of the polylactic acid resin. 押出機の圧縮部の温度を２００〜２５０℃に調整することを特徴とする請求項１乃至請求項５の何れか１項に記載の型内発泡成形用ポリ乳酸系樹脂発泡粒子の製造方法。 The method for producing foamed polylactic acid-based resin particles for in-mold foam molding according to any one of claims 1 to 5, wherein the temperature of the compression section of the extruder is adjusted to 200 to 250 ° C.
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JP2012025869A (en) * 2010-07-26 2012-02-09 Jsp Corp Method for producing polylactic acid-based resin foamed particle
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