JP2006131703A - Foam and method for producing the same - Google Patents

Foam and method for producing the same Download PDF

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JP2006131703A
JP2006131703A JP2004320405A JP2004320405A JP2006131703A JP 2006131703 A JP2006131703 A JP 2006131703A JP 2004320405 A JP2004320405 A JP 2004320405A JP 2004320405 A JP2004320405 A JP 2004320405A JP 2006131703 A JP2006131703 A JP 2006131703A
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foam
resin
supercritical fluid
mixed resin
mass
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Hideki Suzuki
秀樹 鈴木
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Shin Etsu Polymer Co Ltd
Shin Etsu Chemical Co Ltd
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Shin Etsu Polymer Co Ltd
Shin Etsu Chemical Co Ltd
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  • Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
  • Extrusion Moulding Of Plastics Or The Like (AREA)
  • Molding Of Porous Articles (AREA)
  • Biological Depolymerization Polymers (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To provide a foam comprising a biodegradable resin with excellent handing property of a foaming agent and free from remaining foaming agent in the foam. <P>SOLUTION: The invention relates to the foam obtained by foaming a mixed resin comprising 100 parts by mass of the biodegradable resin and 1.0-300 parts by mass of particles of moisture absorbing material, using a supercritical fluid. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

本発明は、生分解性樹脂を用いた発泡体およびその製造方法に関する。   The present invention relates to a foam using a biodegradable resin and a method for producing the same.

従来、生分解性樹脂からなる発泡体は、発泡剤として水、化学発泡剤、物理発泡剤(フロン、ブタン、二酸化炭素、窒素等)を利用して製造されている(例えば下記特許文献1〜5)。
特開平10−152572号公報 特許第3471810号公報 特許第2609795号公報 特開2003−327735号公報 特開平11−147943号公報
Conventionally, the foam which consists of biodegradable resin is manufactured using water, a chemical foaming agent, and a physical foaming agent (CFC, butane, a carbon dioxide, nitrogen, etc.) as a foaming agent (for example, the following patent documents 1-1). 5).
Japanese Patent Laid-Open No. 10-152572 Japanese Patent No. 3471810 Japanese Patent No. 2609795 JP 2003-327735 A Japanese Patent Laid-Open No. 11-147743

しかし、これらの発泡剤を用いた場合、発泡剤の残渣が発泡体中に残ったり、例えばブタンなどは可燃性ガスであるため発泡剤そのものの取り扱い性が問題となっている。
また、生分解性樹脂は加水分解作用により最終的には分解に至る性質を有することを特徴とするものであるが、吸湿が生じると分解が促進され、短期間のうちに物性の劣化が生じ易いという不都合がある。
However, when these foaming agents are used, a residue of the foaming agent remains in the foam or, for example, butane is a flammable gas, so that the handling property of the foaming agent itself is a problem.
In addition, biodegradable resins are characterized by having a property that ultimately leads to degradation by hydrolytic action. However, when moisture absorption occurs, degradation is accelerated and physical properties deteriorate within a short period of time. There is an inconvenience that it is easy.

本発明は、上記事情に鑑みてなされたものであって、生分解性樹脂からなる発泡体であって、発泡剤の取り扱い性が良く、発泡体中に発泡剤の残渣が残らない発泡体およびその製造方法を提供することを目的とする。
また好ましくは、生分解性樹脂の吸湿による物性劣化が抑えられるようにした発泡体およびその製造方法を提供することを目的とする。
The present invention has been made in view of the above circumstances, and is a foam made of a biodegradable resin. The foam has good handleability of the foaming agent, and no foaming agent residue remains in the foam. It aims at providing the manufacturing method.
It is also desirable to provide a foam and a method for producing the same, in which deterioration of physical properties due to moisture absorption of the biodegradable resin can be suppressed.

上記の目的を達成するために、本発明は、生分解性樹脂100質量部と、粒子状吸湿性材料1.0〜300質量部を含有する混合樹脂を超臨界流体を用いて発泡させてなることを特徴とする発泡体を提供する。
前記生分解性樹脂が、脂肪族ポリエステルおよび/または脂肪族−芳香族コポリエステルを含有することが好ましい。
前記超臨界流体が窒素または二酸化炭素のいずれか一方であることが好ましい。
前記粒子状吸湿性材料が無機化合物からなり、平均粒径が0.1μm〜50μmであることが好ましい。
好ましい態様において、発泡体の発泡倍率が1.1〜30である。
In order to achieve the above object, the present invention foams a mixed resin containing 100 parts by mass of a biodegradable resin and 1.0 to 300 parts by mass of a particulate hygroscopic material using a supercritical fluid. A foam is provided.
The biodegradable resin preferably contains an aliphatic polyester and / or an aliphatic-aromatic copolyester.
The supercritical fluid is preferably either nitrogen or carbon dioxide.
It is preferable that the particulate hygroscopic material is made of an inorganic compound and has an average particle size of 0.1 μm to 50 μm.
In a preferred embodiment, the foam has an expansion ratio of 1.1 to 30.

また本発明は、本発明の発泡体を製造する方法であって、生分解性樹脂100質量部と、粒子状吸湿性材料1.0〜300質量部を含有する混合樹脂を加熱溶融させた状態で、超臨界流体を該混合樹脂中に導入する工程と、超臨界流体が導入された混合樹脂を融点以上、融点+10℃以下の温度範囲内まで冷却させる工程と、前記冷却された混合樹脂を押出成形する工程を有することを特徴とする発泡体の製造方法を提供する。   Moreover, this invention is the method of manufacturing the foam of this invention, Comprising: The state which heat-melted the mixed resin containing 100 mass parts of biodegradable resin and 1.0-300 mass parts of particulate hygroscopic materials A step of introducing a supercritical fluid into the mixed resin, a step of cooling the mixed resin into which the supercritical fluid has been introduced to a temperature range of a melting point to a melting point + 10 ° C., and the cooled mixed resin. There is provided a method for producing a foam, comprising a step of extruding.

本発明の発泡体は、生分解性樹脂からなる発泡体であり、発泡剤として超臨界流体を用いたものであるので、発泡剤の取り扱い性が良く、発泡体中に発泡剤の残渣が残らない。
また本発明の発泡体は、粒子状吸湿性材料を含有するものであるので、生分解性樹脂の吸湿による物性劣化が抑えられる。
本発明の発泡体の製造方法によれば、生分解性樹脂からなり、発泡剤の取り扱い性が良く、発泡体中に発泡剤の残渣が残らない発泡体を製造することができる。
また本発明の発泡体の製造方法によれば、粒子状吸湿性材料を含有しており、生分解性樹脂の吸湿による物性劣化が抑えられる発泡体を製造することができる。
The foam of the present invention is a foam made of a biodegradable resin and uses a supercritical fluid as a foaming agent. Therefore, the foaming agent is easy to handle, and a residue of the foaming agent remains in the foam. Absent.
Moreover, since the foam of this invention contains a particulate hygroscopic material, the physical property degradation by the moisture absorption of biodegradable resin is suppressed.
According to the method for producing a foam of the present invention, it is possible to produce a foam that is made of a biodegradable resin, has good handleability of the foaming agent, and does not leave a foaming agent residue in the foam.
Moreover, according to the manufacturing method of the foam of this invention, the foam which contains a particulate hygroscopic material and can suppress the physical-property deterioration by moisture absorption of biodegradable resin can be manufactured.

<生分解性樹脂>
本発明における生分解性樹脂組成物としては、脂肪族ポリエステル樹脂、脂肪族−芳香族コポリエステル、ポリブチレンサクシネート、ポリブチレンアジペート、ポリ乳酸、ポリカプロラクトン等の公知の生分解性樹脂から選ばれる1種または2種以上を用いることができる。これらの生分解性樹脂は市販品として入手可能である。中でも、少なくとも脂肪族ポリエステルおよび/または脂肪族−芳香族コポリエステルを含有することが好ましい。特に、脂肪族ポリエステル樹脂、脂肪族−芳香族コポリエステル、または脂肪族ポリエステル樹脂と脂肪族−芳香族コポリエステルの混合物が好適である。また、これらの混合物を主成分として、さらにポリ乳酸系樹脂(例えば、レイシアH440、レイシアH100、レイシアH280、M−151SQ52、いずれも三井化学社製)を含有させてもよい。
<Biodegradable resin>
The biodegradable resin composition in the present invention is selected from known biodegradable resins such as aliphatic polyester resins, aliphatic-aromatic copolyesters, polybutylene succinates, polybutylene adipates, polylactic acid, and polycaprolactone. 1 type (s) or 2 or more types can be used. These biodegradable resins are available as commercial products. Among them, it is preferable to contain at least an aliphatic polyester and / or an aliphatic-aromatic copolyester. In particular, aliphatic polyester resins, aliphatic-aromatic copolyesters, or mixtures of aliphatic polyester resins and aliphatic-aromatic copolyesters are suitable. Further, a polylactic acid-based resin (for example, Lacia H440, Lacia H100, Lacia H280, M-151SQ52, all manufactured by Mitsui Chemicals, Inc.) may be further contained with these mixtures as the main components.

脂肪族ポリエステル樹脂の具体例としては、ビオノーレ#1001、ビオノーレ#3001、ビオノーレ#1903、ビオノーレ#3903、ビオノーレ2001G、ビオノーレ5001G(いずれも商品名、昭和高分子社製)等が挙げられる。
脂肪族−芳香族コポリエステルの具体例としては、ECOFLEX(商品名、BASF社製)等が挙げられる。
Specific examples of the aliphatic polyester resin include Bionore # 1001, Bionore # 3001, Bionore # 1903, Bionore # 3903, Bionore 2001G, Bionore 5001G (all trade names, Showa Polymer Co., Ltd.) and the like.
Specific examples of the aliphatic-aromatic copolyester include ECOFLEX (trade name, manufactured by BASF).

<粒子状吸湿性材料>
本発明における粒子状吸湿性材料としては、吸湿性を有する無機化合物が好ましく用いられる。具体例としてはシリカゲル、アロフェン、ベントナイト、ゼオライト、アルミナシリカゲル、塩化カルシウム、塩化マグネシウム、酸化カルシウム、酸化マグネシウム、酸化ストロンチウム、酸化バリウム、酸化マグネシウムと塩化マグネシウムとの混合物などが挙げられる。
これらの中ではシリカゲル、ベントナイト、酸化カルシウム、および酸化マグネシウムが生分解性樹脂への混合、分散性の点で好ましい。
粒子状吸湿性材料の平均粒径は0.1μm〜50μmが好ましく、より好ましい範囲は0.5〜20μmである。粒子状吸湿性材料の平均粒径が前記範囲内にあると発泡性および発泡体の物性の点で好ましい。
<Particulate hygroscopic material>
As the particulate hygroscopic material in the present invention, a hygroscopic inorganic compound is preferably used. Specific examples include silica gel, allophane, bentonite, zeolite, alumina silica gel, calcium chloride, magnesium chloride, calcium oxide, magnesium oxide, strontium oxide, barium oxide, and a mixture of magnesium oxide and magnesium chloride.
Among these, silica gel, bentonite, calcium oxide, and magnesium oxide are preferable in terms of mixing and dispersibility in the biodegradable resin.
The average particle diameter of the particulate hygroscopic material is preferably 0.1 μm to 50 μm, and more preferably 0.5 to 20 μm. When the average particle diameter of the particulate hygroscopic material is within the above range, it is preferable in terms of foamability and physical properties of the foam.

本発明において、粒子状吸湿性材料は、生分解性樹脂からなる発泡体中に存在することにより該生分解性樹脂の吸湿による物性低下を抑制する吸湿剤として作用するほか、超臨界流体を発泡剤として発泡体を形成する際に、発泡セルを形成するための核剤として作用する。
粒子状吸湿性材料の使用量は、生分解性樹脂100質量部に対して1.0〜300質量部の範囲で、要求される性能等により適宜設定される。粒子状吸湿性材料の使用量が多いほど吸湿性能は向上するが、多すぎると発泡体の柔軟性が低下する傾向がある。したがって、上記生分解性樹脂100質量部に対する粒子状吸湿性材料の使用量は、発泡体の柔軟性を重視する場合は、1.0質量部以上50質量部以下であることが好ましく、1.2〜30質量部程度がより好ましく、さらに好ましくは2.0〜20質量部である。上記範囲の下限値より少ないと核剤としての作用が十分に得られず、又吸湿性能にも劣る。
一方、発泡体における吸湿性能を重視する場合は、50質量部を超えて300質量部未満であることが好ましい。より好ましい使用量の範囲は100〜250質量部であり、さらに好ましくは150〜200質量部である。上記範囲の上限値を超えると成形が困難となるばかりでなく、相対的に生分解性樹脂の含有割合が低くなる結果、発泡体としての緩衝効果、柔軟性が悪くなる。
In the present invention, the particulate hygroscopic material acts as a hygroscopic agent that suppresses deterioration of physical properties due to moisture absorption of the biodegradable resin by being present in the foam made of the biodegradable resin, and also foams a supercritical fluid. When forming a foam as an agent, it acts as a nucleating agent for forming foam cells.
The usage-amount of a particulate hygroscopic material is suitably set by the performance etc. which are requested | required in the range of 1.0-300 mass parts with respect to 100 mass parts of biodegradable resin. As the amount of the particulate hygroscopic material used increases, the hygroscopic performance improves, but if too much, the flexibility of the foam tends to decrease. Accordingly, the amount of the particulate hygroscopic material used with respect to 100 parts by mass of the biodegradable resin is preferably 1.0 part by mass or more and 50 parts by mass or less when importance is attached to the flexibility of the foam. About 2-30 mass parts is more preferable, More preferably, it is 2.0-20 mass parts. When the amount is less than the lower limit of the above range, a sufficient effect as a nucleating agent cannot be obtained, and the hygroscopic performance is inferior.
On the other hand, when emphasizing the hygroscopic performance of the foam, it is preferably more than 50 parts by mass and less than 300 parts by mass. The range of the more preferable usage-amount is 100-250 mass parts, More preferably, it is 150-200 mass parts. Exceeding the upper limit of the above range not only makes molding difficult, but also results in a relatively low content of the biodegradable resin, resulting in poor cushioning effect and flexibility as a foam.

<製造方法>
図1は、本発明の発泡体の製造方法に好適に用いられる押出成形機の一例を示した概略構成図である。この例の押出成形機は、一段目の押出機1と二段目の押出機2とが連結されており、一段目の押出機1の途中で超臨界流体が注入されるように概略構成されている。図中符号3は超臨界流体注入部を示す。また二段目の押出機2の出口にはダイ6が連結されている。なお図示していないが、二段目の押出機2には、内部を冷却するための冷却手段が設けられている。なお、二段目の押出機を設けず、一段目の押出機で冷却する構成とすることも可能である。
図中符号4は一段目の押出機1と二段目の押出機2との連結部(第1の連結部という)を示し、5は二段目の押出機2とダイ6との連結部(第2の連結部という)を示している。
<Manufacturing method>
FIG. 1 is a schematic configuration diagram showing an example of an extrusion molding machine suitably used in the method for producing a foam of the present invention. The extrusion molding machine in this example is configured so that a first stage extruder 1 and a second stage extruder 2 are connected, and a supercritical fluid is injected in the middle of the first stage extruder 1. ing. Reference numeral 3 in the figure indicates a supercritical fluid injection part. A die 6 is connected to the outlet of the second stage extruder 2. Although not shown, the second-stage extruder 2 is provided with a cooling means for cooling the inside. It is also possible to employ a configuration in which the second stage extruder is not provided and the first stage extruder is used for cooling.
Reference numeral 4 in the figure denotes a connecting portion (referred to as a first connecting portion) between the first-stage extruder 1 and the second-stage extruder 2, and 5 denotes a connecting portion between the second-stage extruder 2 and the die 6. (Referred to as a second connecting portion).

以下、本発明の発泡体の製造方法の一実施形態として、図1の押出成形機を用い、押出成形法により発泡体を製造する方法を説明する。
まず、生分解性樹脂と粒子状吸湿性材料を含有する混合樹脂を調製する。好ましくは、予め、生分解性樹脂と粒子状吸湿性材料を混合した混合樹脂をペレット状に成形しておく。該混合樹脂は、例えば二軸混練機や加圧ニーダー等の一般的な混合装置を用いて各材料を均一に混合分散することによって調製することができる。該混合樹脂には、本発明の効果を損なわない範囲で適宜の添加剤を含有させてもよい。
Hereinafter, as an embodiment of the method for producing a foam of the present invention, a method for producing a foam by an extrusion molding method using the extruder shown in FIG. 1 will be described.
First, a mixed resin containing a biodegradable resin and a particulate hygroscopic material is prepared. Preferably, a mixed resin obtained by mixing a biodegradable resin and a particulate hygroscopic material is previously formed into a pellet shape. The mixed resin can be prepared by uniformly mixing and dispersing the respective materials using a general mixing apparatus such as a biaxial kneader or a pressure kneader. The mixed resin may contain an appropriate additive as long as the effects of the present invention are not impaired.

次に、前記混合樹脂を一段目の押出機1に投入して加熱溶融させる。そして、超臨界流体注入部3で、溶融状態にある混合樹脂中に超臨界流体を注入する。
本発明において用いられる超臨界流体は、臨界温度以上かつ臨界圧力以上とすることにより超臨界状態となった流体であり、具体的には超臨界二酸化炭素または超臨界窒素等が好ましい。
超臨界流体の注入量は、混合樹脂の伸張粘度や溶融張力等の物性を考慮して、所望の発泡倍率の発泡体が得られるように適宜設定することができる。
Next, the mixed resin is charged into the first stage extruder 1 and melted by heating. Then, the supercritical fluid injection unit 3 injects the supercritical fluid into the mixed resin in the molten state.
The supercritical fluid used in the present invention is a fluid that has become a supercritical state by setting the temperature to a critical temperature or higher and a critical pressure or higher. Specifically, supercritical carbon dioxide or supercritical nitrogen is preferable.
The injection amount of the supercritical fluid can be appropriately set so as to obtain a foam having a desired expansion ratio in consideration of physical properties such as extensional viscosity and melt tension of the mixed resin.

超臨界流体が注入された溶融状態の混合樹脂は、第1の連結部4を介して二段目の押出機2に連続的に送られ、該押出機2内を通る間に所定の冷却温度まで冷却される。
混合樹脂の冷却温度は、融点以上、融点+10℃以下の温度範囲が好ましく、より好ましくは融点+5℃以上である。混合樹脂の冷却温度を上記範囲内とすることにより、混合樹脂の伸張粘度、溶融張力を高めることができる。なお、ここでの混合樹脂の融点は、原料として用いた生分解性樹脂の融点であり、2種以上の生分解性樹脂を併用した場合は、混合割合が高い方の樹脂の融点となる。
この後、冷却された混合樹脂がダイ6から押し出され、混合樹脂中の超臨界流体が常圧に減圧されて気相へ相変化することにより発泡が生じ、発泡体が得られる。
The molten mixed resin into which the supercritical fluid has been injected is continuously sent to the second-stage extruder 2 via the first connecting portion 4, and a predetermined cooling temperature is passed through the extruder 2. Until cooled.
The cooling temperature of the mixed resin is preferably in the temperature range from the melting point to the melting point + 10 ° C., more preferably the melting point + 5 ° C. or more. By setting the cooling temperature of the mixed resin within the above range, the extension viscosity and melt tension of the mixed resin can be increased. The melting point of the mixed resin here is the melting point of the biodegradable resin used as a raw material, and when two or more kinds of biodegradable resins are used in combination, the melting point of the resin having the higher mixing ratio.
Thereafter, the cooled mixed resin is pushed out from the die 6, and the supercritical fluid in the mixed resin is decompressed to normal pressure and phase-changed to the gas phase, thereby generating foam and obtaining a foam.

このようにして得られる発泡体は、生分解性樹脂層内に中空の発泡セルが多数存在し、該発泡セル内において粒子状吸湿性材料の表面のうちの少なくとも一部が露出している構造を有する。
発泡体の発泡倍率(発泡前の混合樹脂の比重/発泡体の比重)は、低すぎると良好な発泡状態が得られないので1.1以上が好ましく、1.5以上がより好ましい。発泡倍率の上限は特に制限されず、要求される機械的強度等の特性に応じて適宜設定することができるが、本発明によれば発泡倍率30程度の高倍率の発泡体を製造することができる。該発泡倍率のより好ましい範囲は、発泡体の用途にもよるが、例えば1.5〜30程度であり、さらに好ましい範囲は3.0〜20程度である。
発泡体の形状は特に制限されず、押出成形や射出成形等、用いる成形法により成形可能な形状であればよい。具体例としてはフィルム、シート、その他の形状の成形体等が挙げられる。
The foam thus obtained has a structure in which a large number of hollow foam cells exist in the biodegradable resin layer, and at least a part of the surface of the particulate hygroscopic material is exposed in the foam cells. Have
The foam expansion ratio (specific gravity of the mixed resin before foaming / specific gravity of the foam) is preferably 1.1 or more, and more preferably 1.5 or more, since a good foamed state cannot be obtained if it is too low. The upper limit of the expansion ratio is not particularly limited, and can be appropriately set according to required characteristics such as mechanical strength. According to the present invention, a foam with a high expansion ratio of about 30 can be manufactured. it can. A more preferable range of the expansion ratio is, for example, about 1.5 to 30, and a more preferable range is about 3.0 to 20, although it depends on the use of the foam.
The shape of the foam is not particularly limited, and may be a shape that can be molded by a molding method used such as extrusion molding or injection molding. Specific examples include films, sheets, and other shaped molded bodies.

上記実施形態の製造方法によれば、生分解性樹脂と粒子状吸湿性材料を含有する混合樹脂中に注入された超臨界流体が可塑剤として作用し、該混合樹脂の流動性が向上する。このため、粒子状吸湿性材料を配合させることによって樹脂の流動性が低下して成形性が悪くなるのが防止される。したがって、粒子状吸湿性材料を配合して、生分解性樹脂の吸湿による物性劣化が抑制された発泡体を得ることができる。   According to the manufacturing method of the above embodiment, the supercritical fluid injected into the mixed resin containing the biodegradable resin and the particulate hygroscopic material acts as a plasticizer, and the fluidity of the mixed resin is improved. For this reason, mixing the particulate hygroscopic material prevents the fluidity of the resin from being lowered and the moldability from being deteriorated. Therefore, a foam in which deterioration of physical properties due to moisture absorption of the biodegradable resin is suppressed can be obtained by blending the particulate hygroscopic material.

また、上記のように超臨界流体の注入により混合樹脂の流動性が向上するので、二段目の押出機2において、ダイ6から押し出す前の混合樹脂を融点近傍まで冷却しても、良好な流動性が得られる。すなわち、混合樹脂の冷却温度の制限が緩和されるので、冷却温度条件の制御により伸張粘度、溶融張力をより好ましい範囲に設定することができる。これにより、発泡体の発泡状態をコントロールして、より良好な発泡状態の発泡体を得ることができる。例えば、発泡セルが微細なもの、いわゆるマイクロセルを有する発泡体や、逆にセルが大きくて発泡による緩衝効果が高い成形品やシートを製造することができる。
さらに、発泡剤として用いる超臨界流体は取り扱い性が良く、発泡体中に残渣が残らないという利点を有する。
In addition, since the fluidity of the mixed resin is improved by injecting the supercritical fluid as described above, even if the mixed resin before being extruded from the die 6 is cooled to the vicinity of the melting point in the second-stage extruder 2, it is good. Fluidity is obtained. That is, since the restriction of the cooling temperature of the mixed resin is relaxed, the extensional viscosity and the melt tension can be set to more preferable ranges by controlling the cooling temperature condition. Thereby, the foaming state of a foam can be controlled and the foam of a more favorable foaming state can be obtained. For example, a foam having fine foam cells, that is, a foam having a so-called micro cell, or a molded article or sheet having a large cell and a high cushioning effect by foaming can be produced.
Furthermore, the supercritical fluid used as the foaming agent has good handleability and has the advantage that no residue remains in the foam.

本発明の発泡体は、例えば緩衝材(シート、成形品)、乾燥剤成形体、シートを二次加工して得られる容器等、一般的な発泡材の用途に適用可能であるほか、吸湿性を有するので乾燥材としても利用可能である。また、生分解性樹脂からなるので、例えば土中や水中等で生分解するものであり、焼却せずに廃棄処分することができ、環境上好ましい。   The foam of the present invention can be applied to general foam materials such as cushioning materials (sheets, molded products), desiccant molded products, containers obtained by secondary processing of sheets, etc. It can be used as a desiccant. Further, since it is made of a biodegradable resin, it is biodegradable in, for example, soil or water, and can be disposed of without incineration, which is environmentally preferable.

(実施例1〜7)
下記表1に示す組成で生分解性樹脂と粒子状吸湿性材料を混合して混合樹脂を得、この混合樹脂をペレット状に成形した。
・表1における生分解性樹脂(1)(2)(3)としてそれぞれ次のものを用いた。
生分解性樹脂(1)…脂肪族ポリエステル、製品名:ビオノーレ#1903、昭和高分子社製、融点116℃。
生分解性樹脂(2)…脂肪族ポリエステル、製品名:ビオノーレ#3903、昭和高分子社製、融点88℃。
生分解性樹脂(3)…脂肪族−芳香族コポリエステル、製品名:エコフレックス、ビーエーエスエフ社製、融点125℃。
・下記表1における粒子状吸湿性材料は、平均粒径1μmの酸化カルシウム(CaO)である。
(Examples 1-7)
A biodegradable resin and a particulate hygroscopic material were mixed with the composition shown in Table 1 to obtain a mixed resin, and the mixed resin was molded into a pellet.
-The following were used as biodegradable resins (1), (2), and (3) in Table 1, respectively.
Biodegradable resin (1): aliphatic polyester, product name: Bionore # 1903, manufactured by Showa Polymer Co., Ltd., melting point 116 ° C.
Biodegradable resin (2): Aliphatic polyester, product name: Bionore # 3903, Showa Polymer Co., Ltd., melting point 88 ° C.
Biodegradable resin (3): aliphatic-aromatic copolyester, product name: Ecoflex, manufactured by BASF, melting point 125 ° C.
The particulate hygroscopic material in the following Table 1 is calcium oxide (CaO) having an average particle diameter of 1 μm.

上記で調製した混合樹脂を用いてシート状の発泡体を成形した。
成形は、図1に示す構成の押出成形機を用い押出成形した。
すなわち、上記でペレット状に成形した混合樹脂を一段目の押出機1に投入し、ここで十分に溶融させた後、超臨界流体注入部3で超臨界流体を注入した。こうして一段目の押出機1において超臨界流体が注入された溶融状態の混合樹脂は、第1の連結部4を介して二段目の押出機2に連続的に送られ、冷却され、第2の連結部5を介してダイ6から押し出される。こうして発泡体を得た。
なお一段目の押出機1のバレル内径(口径)は65mm、二段目の押出機2のバレル内径は75mmとした。
A sheet-like foam was formed using the mixed resin prepared above.
The molding was performed by using an extrusion molding machine having the configuration shown in FIG.
That is, the mixed resin formed into a pellet shape as described above was charged into the first-stage extruder 1 and sufficiently melted therein, and then the supercritical fluid was injected by the supercritical fluid injection unit 3. The molten mixed resin into which the supercritical fluid has been injected in the first-stage extruder 1 is continuously sent to the second-stage extruder 2 via the first connecting portion 4, cooled, and second It is extruded from the die 6 through the connecting portion 5. A foam was thus obtained.
The barrel inner diameter (portion) of the first stage extruder 1 was 65 mm, and the barrel inner diameter of the second stage extruder 2 was 75 mm.

各実施例における条件を下記表1に示す。
・下記表1における超臨界流体は、超臨界窒素(表中ではNと記載)または超臨界二酸化炭素(表中ではCOと記載)である。
・下記表1における樹脂吐出量Aは、超臨界流体を注入しない状態においてダイ6から吐出される混合樹脂の吐出量(単位;kg/h)の測定結果である。
・下記表1における超臨界流体注入量Bは、超臨界流体注入部3から一段目の押出機1内に注入される超臨界流体の注入量(単位;kg/h)の測定結果である。
・下記表1における注入割合Cは、上記B/A×100で求められる値(単位;質量%)である。
・ダイ6としては、Tダイまたは丸ダイを用いた。Tダイは直線スリットからなる吐出口を有するもので、該吐出口の長さが300mmのものを用いた。一方、丸ダイは環状スリットからなる吐出口を有するもので、該吐出口の径が50mmのものを用いた。丸ダイを用いた場合は、丸ダイから押出成形された円筒状の成形物を、長さ方向に沿って切り開くことによりシート状にした。
・表1中の温度は、第2の連結部5内における混合樹脂の温度の測定結果である。
The conditions in each example are shown in Table 1 below.
The supercritical fluid in the following Table 1 is supercritical nitrogen (described as N 2 in the table) or supercritical carbon dioxide (described as CO 2 in the table).
The resin discharge amount A in Table 1 below is a measurement result of the discharge amount (unit: kg / h) of the mixed resin discharged from the die 6 in a state where the supercritical fluid is not injected.
The supercritical fluid injection amount B in Table 1 below is a measurement result of the injection amount (unit: kg / h) of the supercritical fluid injected from the supercritical fluid injection part 3 into the first stage extruder 1.
-The injection | pouring ratio C in following Table 1 is a value (unit; mass%) calculated | required by said B / Ax100.
-As the die 6, a T die or a round die was used. The T die had a discharge port composed of a straight slit, and the discharge port had a length of 300 mm. On the other hand, the round die has a discharge port composed of an annular slit, and the discharge port has a diameter of 50 mm. When a round die was used, a cylindrical shaped product extruded from the round die was cut into a sheet shape along the length direction.
The temperature in Table 1 is a measurement result of the temperature of the mixed resin in the second connecting portion 5.

得られたシート状の発泡体について、シートの厚さおよび発泡倍率を測定した。その結果を下記表1に示す。   About the obtained sheet-like foam, the thickness and expansion ratio of the sheet were measured. The results are shown in Table 1 below.

Figure 2006131703
Figure 2006131703

(比較例1)
実施例2において、CaOの配合量を310質量部に変更して、同様の押出成形法によりシート状の発泡体を成形しようとしたが、樹脂の流動性が低すぎて成形不能であった。
(Comparative Example 1)
In Example 2, the amount of CaO was changed to 310 parts by mass and a sheet-like foam was formed by the same extrusion molding method. However, the fluidity of the resin was too low to be molded.

(比較例2)
実施例2において、CaOの配合量を0.5質量部に変更して、同様の押出成形法によりシート状の発泡体を成形したが、良好な発泡状態は得られなかった。
(Comparative Example 2)
In Example 2, the amount of CaO was changed to 0.5 parts by mass, and a sheet-like foam was formed by the same extrusion molding method, but a good foamed state was not obtained.

本発明の発泡体の製造方法に好適に用いられる押出成形機の一例を示した概略構成図である。It is the schematic block diagram which showed an example of the extruder suitably used for the manufacturing method of the foam of this invention.

符号の説明Explanation of symbols

1…一段目の押出機、2…二段目の押出機、3…超臨界流体注入部、6…ダイ。

DESCRIPTION OF SYMBOLS 1 ... First stage extruder, 2 ... Second stage extruder, 3 ... Supercritical fluid injection part, 6 ... Die.

Claims (6)

生分解性樹脂100質量部と、粒子状吸湿性材料1.0〜300質量部を含有する混合樹脂を超臨界流体を用いて発泡させてなることを特徴とする発泡体。   A foam obtained by foaming a mixed resin containing 100 parts by mass of a biodegradable resin and 1.0 to 300 parts by mass of a particulate hygroscopic material using a supercritical fluid. 前記生分解性樹脂が、脂肪族ポリエステルおよび/または脂肪族−芳香族コポリエステルを含有することを特徴とする請求項1記載の発泡体   The foam according to claim 1, wherein the biodegradable resin contains an aliphatic polyester and / or an aliphatic-aromatic copolyester. 前記超臨界流体が窒素または二酸化炭素のいずれか一方であることを特徴とする請求項1または2に記載の発泡体。   The foam according to claim 1 or 2, wherein the supercritical fluid is either nitrogen or carbon dioxide. 前記粒子状吸湿性材料が無機化合物からなり、平均粒径が0.1μm〜50μmであることを特徴とする請求項1〜3のいずれか一項に記載の発泡体。   The foam according to any one of claims 1 to 3, wherein the particulate hygroscopic material is made of an inorganic compound and has an average particle diameter of 0.1 µm to 50 µm. 発泡体の発泡倍率が1.1〜30であることを特徴とする請求項1〜4のいずれか一項に記載の発泡体。   The foam according to any one of claims 1 to 4, wherein the foam has a foaming ratio of 1.1 to 30. 請求項1〜5のいずれか一項に記載の発泡体を製造する方法であって、
生分解性樹脂100質量部と、粒子状吸湿性材料1.0〜300質量部を含有する混合樹脂を加熱溶融させた状態で、超臨界流体を該混合樹脂中に導入する工程と、超臨界流体が導入された混合樹脂を融点以上、融点+10℃以下の温度範囲内まで冷却させる工程と、前記冷却された混合樹脂を押出成形する工程を有することを特徴とする発泡体の製造方法。

A method for producing the foam according to any one of claims 1 to 5,
Introducing a supercritical fluid into the mixed resin in a state where 100 parts by mass of the biodegradable resin and 1.0 to 300 parts by mass of the particulate hygroscopic material are heated and melted; A method for producing a foam, comprising: a step of cooling a mixed resin into which a fluid is introduced to a temperature range of a melting point or higher and a melting point + 10 ° C. or lower; and a step of extruding the cooled mixed resin.

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