JP3529175B2 - Method for producing foamed thermoplastic polyester resin product - Google Patents
Method for producing foamed thermoplastic polyester resin productInfo
- Publication number
- JP3529175B2 JP3529175B2 JP31855894A JP31855894A JP3529175B2 JP 3529175 B2 JP3529175 B2 JP 3529175B2 JP 31855894 A JP31855894 A JP 31855894A JP 31855894 A JP31855894 A JP 31855894A JP 3529175 B2 JP3529175 B2 JP 3529175B2
- Authority
- JP
- Japan
- Prior art keywords
- sheet
- mold
- thermoplastic polyester
- polyester resin
- molded product
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Landscapes
- Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
- Blow-Moulding Or Thermoforming Of Plastics Or The Like (AREA)
- Molding Of Porous Articles (AREA)
Description
【発明の詳細な説明】
【０００１】
【産業上の利用分野】本発明は熱可塑性ポリエステル樹
脂発泡成形品の製造方法に関する。
【０００２】
【従来の技術】従来、熱可塑性樹脂発泡成形品を製造す
るには、１次発泡シートをクランプなどで固定し、雌雄
の加熱金型でシートを挟み込み、金型内において型内発
泡（２次発泡）させて所望の成形品を得る方法が一般的
に知られている。
【０００３】また、成形品を多数個取りするために、雄
型と雌型との間に各々の成形品の輪郭となる部分を押え
つける仕切板を挟んで成形する方法なども知られている
（例えば特開昭５８−１９３１２３号公報）。
【０００４】更に、熱可塑性ポリエステル樹脂発泡成形
品を製造するには、種々の公知の方法により発泡シート
を作製し、発泡シートが軟化するまで予備加熱した後、
真空成形機の加熱金型を用いて成形と同時に熱による結
晶化を起こさせて耐熱性を付与し、更に冷却用金型を用
いて外観形状を均一にする方法が知られている（プラス
チックス、Ｖｏｌ．４３、Ｎｏ．６、ｐ．１２１−１２
６、１９９２）。なお、発泡シートを作製する方法とし
ては、サーキュラーダイを使用して微細な気泡をもつ縞
のない熱可塑性ポリエステル樹脂発泡シートを製造する
方法（例えば特開平４−２２９４２３号公報）などが知
られている。
【０００５】
【発明が解決しようとする課題】しかしながら、上述し
た従来のいずれの方法でも既に発泡した１次発泡シート
を使用しているため、これをクランプや仕切板などで強
く押えつけても、その部分が無発泡になることはない。
このため、得られた成形品の輪郭部分は横方向又は上方
向からの力に弱いという欠点があった。特に、この輪郭
部分の発泡倍率が５倍以上になると、成形品の形状をど
のように工夫しても機械的強度の不足が避けられなかっ
た。
【０００６】また、従来の方法でカップなどの成形品を
作製する場合には、成形時にカップの側面に対応する部
分のシートが延伸されて気泡が楕円形状に歪むため、得
られる成形品の機械的強度が部分によって不均一になる
という問題があった。
【０００７】更に、従来の方法により深絞り成形しよう
としても、１次発泡シートは伸びが小さいため、発泡シ
ートが成形時の延伸に耐えきれなくなって発泡シートが
破れることがあった。このため、従来の方法では深絞り
成形は困難であった。
【０００８】本発明はかかる問題点に鑑みてなされたも
のであり、熱可塑性ポリエステル樹脂シートから発泡成
形品を製造する場合に、機械的強度が高く、成形品の部
分によって機械的強度のばらつきがない成形品を得るこ
とができ、深絞り成形にも好適な方法を提供することを
目的とする。
【０００９】
【課題を解決するための手段と作用】本発明の熱可塑性
ポリエステル樹脂発泡成形品の製造方法は、熱可塑性ポ
リエステル樹脂シートに発泡剤として不活性ガスを含有
させる工程と、前記シートを真空成形機中に保持し、前
記シートの両面に成形品の輪郭部分に対応する形状を有
し金型が挿入される穴が設けられた押え板を圧着させる
工程と、雄型の加熱金型を前記押え板に設けられた穴を
通して前記シートに圧着させ、前記シートの前記金型に
接した部分を選択的に発泡させるとともに、前記金型に
設けられた微細孔より真空引きしてシートを成形する工
程と、真空引きを停止し、前記工程で得られた成形品か
ら前記金型を離した後、成形品を冷却する工程とを具備
したことを特徴とするものである。
【００１０】以下、本発明を更に詳細に説明する。本発
明の方法では、まず熱可塑性ポリエステル樹脂シートに
発泡剤として不活性ガスを含有させる。
【００１１】ここで用いられる熱可塑性ポリエステル樹
脂としては、ポリエチレンテレフタレート、ポリブチレ
ンテレフタレート又はこれらのベース樹脂とポリカーボ
ネートなどとからなる各種のポリマーアロイが挙げられ
るが、これらのうちポリエチレンテレフタレートが特に
好ましい。
【００１２】熱可塑性ポリエステル樹脂には、樹脂本来
の特性を損なわない範囲で、結晶化核剤、結晶化促進
剤、気泡化核剤、抗酸化剤、帯電防止剤、紫外線防止
剤、顔料、染料、滑剤などの各種添加剤を配合してもよ
い。
【００１３】熱可塑性ポリエステル樹脂に含有させる不
活性ガスとしては、ヘリウム、窒素、二酸化炭素、アル
ゴンなどが挙げられる。これらの不活性ガスのうちで
は、樹脂中の含有量を多くできることから二酸化炭素が
特に好ましい。
【００１４】本発明において、発泡剤として不活性ガス
を含有する熱可塑性ポリエステル樹脂シートを調製する
には、例えばＵＳＰ−４４７３６６５号に記載されてい
る方法を用いることができる。この方法は、押出機によ
り均一な厚みに制御して成形した熱可塑性ポリエステル
樹脂シートをロール状に巻き、これを高圧容器内に収納
して不活性ガスを高圧下で含浸させるものである。ま
た、例えば特開平４−２６８３４５号に開示されている
方法を用いることもできる。この方法は、押出機中で溶
融状態にある熱可塑性ポリエステル樹脂に発泡剤として
不活性ガスを注入し、樹脂の発泡を完全に抑制しながら
冷却することにより不活性ガスを含有する熱可塑性ポリ
エステル樹脂シートを調製するものである。いずれの方
法を用いても、この段階では樹脂シートはまだ発泡して
いない。
【００１５】次に、不活性ガスを含有させたシートを真
空成形機中に保持し、シートの両面に成形品の輪郭部分
（成形品の開口の周辺部分）に対応する形状を有し金型
が挿入される穴が設けられた押え板を圧着させる。押え
板には、１個の穴だけを設けてもよいし、成形品の多数
個取りができるように複数個の穴を設けてもよい。シー
トに対する押え板の圧着力は１０ｋｇ／ｃｍ2 以上とす
ることが望ましい。圧着時の押え板の温度は樹脂シート
の軟化温度以下とする必要がある。これは、押え板の温
度が樹脂シートの軟化温度よりも高くなると圧着と同時
に発泡が開始するため、圧着部分の無発泡状態を維持で
きなくなるためである。また、成形回数の増加に伴い、
加熱金型の輻射熱により押え板の温度が上昇するため、
圧着時の押え板が常に樹脂シートの軟化温度以下となる
ように冷媒などを用いて冷却する。なお、後工程におけ
る加熱金型の圧着後に押え板の温度が樹脂シートの軟化
温度より多少高くなることは許容される。
【００１６】次いで、雄型の加熱金型を押え板に設けら
れた穴を通して不活性ガスを含有させた樹脂シートに圧
着させ、シートの金型に接した部分を選択的に発泡させ
るとともに、金型に設けられた微細孔より真空引きして
シートを所望の形状に成形する。この際、加熱金型によ
る加熱温度、加熱時間などの条件は、目的とする成形品
の深絞りの度合などに応じて適宜設定する。
【００１７】最後に、真空引きを停止し、前記工程で得
られた成形品から金型を離した後、成形品を冷却して、
目的とする成形品を製造する。本発明の方法では、発泡
剤として不活性ガスを含有させただけで未発泡の熱可塑
性ポリエステル樹脂シートの両面を押え板で圧着し、雄
型加熱金型を押え板に設けられた穴を通してシートに圧
着させ、金型に接した部分を選択的に発泡させるので、
押え板で押えられた輪郭部分（成形品の開口の周辺部
分）が無発泡となっている成形品を得ることができる。
このように成形品の輪郭部分が無発泡であるので機械的
強度が高く、手で掴むときに受ける横からの力や輪郭部
分を別の樹脂でラップするときの受ける上からの力など
による変形に対して非常に強くなる。また、輪郭部分の
強度を増強するための端部の折り返しなどの工夫も不必
要になる。
【００１８】また本発明の方法では加熱発泡と同時に真
空成形を行うため、可塑化効果が大きい熱可塑性ポリエ
ステル樹脂シートに対して成形時の伸びとともに発泡時
の気泡成長に伴う伸びが加わり、シートを大幅に伸長さ
せることができる。このため、本発明の方法は深絞り成
形に非常に好適である。しかも、真空成形時にシートに
無理な変形力が加わらないため、気泡の変形やつぶれが
ほとんどなく、部分によって機械的強度のばらつきのな
い発泡成形品が得られる。
【００１９】
【実施例】以下、本発明の実施例を説明する。図１は下
記の実施例で熱可塑性ポリエステル樹脂発泡成形品を製
造するために用いた真空成形機の構成を示す図である。
真空成形機１の内部上面及び下面にはそれぞれ複数の支
持柱２が上下動可能に取り付けられ、これらの支持柱２
によって上下の押え板３が支持される。これらの押え板
３は成形品の輪郭部分に対応する形状を有し、金型が挿
入される穴が設けられている。押え板３の穴は例えば２
列×３段に設けられ、６個取りできるようになってい
る。真空成形機１の内部下面には保持台４が上下動可能
に取り付けられ、その上端に雄型の加熱金型５が保持さ
れる。発泡剤として不活性ガスを含有する巻体から熱可
塑性ポリエステル樹脂のシート１１が真空成形機１内に
送られて本発明の方法に従った所定の工程を経ることに
より、例えばカップ状をなす発泡成形品１２が製造され
る。
【００２０】（実施例１）結晶化核剤を含有するポリエ
チレンテレフタレート樹脂（ユニチカ（株）社製、商品
名：Ｃ−０３１２）を除湿乾燥機にて１４０℃で５時間
乾燥させた。この樹脂を押出機に供給して溶融混練した
後、０．５ｍｍ厚さのシート状に押出成形し、このポリ
エチレンテレフタレート樹脂シートをロールに巻き取っ
た。次に、ポリエチレンテレフタレート樹脂シート巻体
を高圧容器内に収納し、容器内に発泡剤として６０ｋｇ
／ｃｍ2 の炭酸ガスを充填した。シート巻体に炭酸ガス
を２４時間含浸させた後、高圧容器から取り出した。
【００２１】このシート巻体を図１に示すように真空成
形機１の外側にセットした。巻体からシート１１を真空
成形機中に送り、支持柱２を作動させてシート１１の上
下両面に押え板３を圧着させた。この状態で保持台４を
作動させて下方から２４０℃に加熱した雄型の加熱金型
５を押え板３に２列×３段に設けられた６個の穴を通し
てシート１１に圧着させ、シート１１の金型５に接した
部分を選択的に発泡させるとともに、金型５に設けられ
た微細孔より真空引きしてシートを成形した。次いで、
真空引きを停止し、成形品から金型５を離した後、成形
品を冷却して、開口の直径と深さとの比が２：１で内容
積２００ｃｃのカップ状発泡成形品１２を製造した。
【００２２】得られた成形品の側面部及び底面部の断面
を走査電子顕微鏡（ＳＥＭ）により観察したところ、い
ずれの部分においても気泡形状に変形は認められなかっ
た。成形品の側面部及び底面部からそれぞれダンベル形
状の試料を打ち抜き、引っ張り強度を測定したところ、
両者の強度にはほとんど差が認められなかった。
【００２３】また、成形品に１５０ｃｃの水を入れ輪郭
部分（上部開口の周辺部分）を手で掴んで持ち上げたと
きの開口部の変形率を測定したところ、変形率は３％以
下と非常に小さいものであった。
【００２４】（比較例１）実施例１と同一のポリエチレ
ンテレフタレート樹脂を実施例１と全く同様に処理して
０．５ｍｍ厚さのポリエチレンテレフタレート樹脂シー
トをロールに巻き取って炭酸ガスを含浸させた。
【００２５】得られたシート巻体からシートを熱風循環
式の発泡炉中に通し、シート表面温度が２２０℃になる
ように加熱して発泡させ、均一に発泡した微細な気泡を
有するポリエチレンテレフタレート樹脂発泡シートを作
製した。
【００２６】得られたポリエチレンテレフタレート樹脂
発泡シートを、加熱ヒーターと成形金型とを有する一般
的な真空成形機を用いて成形し、開口直径と深さとの比
が２：１で内容積２００ｃｃのカップ状発泡成形品を製
造した。
【００２７】得られた成形品では、側面部の厚みが底面
部に比べて１／３以下になっていた。この成形品の側面
部及び底面部の断面を走査電子顕微鏡（ＳＥＭ）により
観察したところ、側面部断面の気泡形状は偏平に引き延
ばされた楕円形になっていた。成形品の側面部及び底面
部からそれぞれダンベル形状の試料を打ち抜き、引っ張
り強度を測定したところ、側面部の強度は底面部に比べ
て１／４以下と非常に低いものであった。このように、
側面部が薄くしかも側面部に含有されている気泡が変形
する結果、側面部の強度が低下していることが判明し
た。
【００２８】また、成形品に１５０ｃｃの水を入れ輪郭
部分（上部開口の周辺部分）を手で掴んで持ち上げたと
きの開口部の変形率を測定したところ、変形率は２５％
と実施例１と比較して約８倍も大きくなった。
【００２９】（実施例２）ポリエチレンテレフタレート
樹脂（ユニチカ（株）社製、商品名：ＳＡ−１２０６）
を除湿乾燥機にて１４０℃で５時間乾燥させた。この樹
脂と結晶化核剤として０．５重量％のタルク（日本タル
ク（株）社製、商品名：ミクロエースＫ−１）とを押出
機に供給して溶融混練した後、０．５ｍｍ厚さのシート
状に押出成形し、このポリエチレンテレフタレート樹脂
シートをロールに巻き取った。次に、ポリエチレンテレ
フタレート樹脂シート巻体を高圧容器内に収納し、容器
内に発泡剤として６０ｋｇ／ｃｍ2 の炭酸ガスを充填し
た。シート巻体に炭酸ガスを２４時間含浸させた後、高
圧容器から取り出した。
【００３０】このシート巻体を図１に示すように真空成
形機１の外側にセットし、実施例１と全く同様に本発明
の方法に従って開口直径と深さとの比が２：１で内容積
２００ｃｃのカップ状発泡成形品１２を製造した。
【００３１】得られた成形品の側面部及び底面部の断面
を走査電子顕微鏡（ＳＥＭ）により観察したところ、い
ずれの部分においても気泡形状に変形は認められなかっ
た。成形品の側面部及び底面部からそれぞれダンベル形
状の試料を打ち抜き、引っ張り強度を測定したところ、
両者の強度にはほとんど差が認められなかった。
【００３２】また、成形品に１５０ｃｃの水を入れ輪郭
部分を手で掴んで持ち上げたときの開口部の変形率を測
定したところ、変形率は４％以下と非常に小さいもので
あった。一方、比較のために従来の方法により１次発泡
したシートから作製された、発泡した輪郭部分を有する
成形品について上記と同様にして開口部の変形率を測定
したところ、変形率は４０％と非常に大きかった。
【００３３】（実施例３）ポリブチレンテレフタレート
樹脂（東レ（株）社製、商品名：１４０１−Ｘ０４）を
除湿乾燥機にて１４０℃で５時間乾燥させた。この樹脂
を押出機に供給して溶融混練した後、０．５ｍｍ厚さの
シート状に押出成形し、このポリブチレンテレフタレー
ト樹脂シートをロールに巻き取った。次に、ポリブチレ
ンテレフタレート樹脂シート巻体を高圧容器内に収納
し、容器内に発泡剤として６０ｋｇ／ｃｍ2 の炭酸ガス
を充填した。シート巻体に炭酸ガスを２４時間含浸させ
た後、高圧容器から取り出した。
【００３４】このシート巻体を図１に示すように真空成
形機１の外側にセットし、加熱金型の温度を２００℃と
した以外は実施例１と全く同様に本発明の方法に従って
開口直径と深さとの比が２：１で内容積２００ｃｃのカ
ップ状発泡成形品１２を製造した。
【００３５】得られた成形品の側面部及び底面部の断面
を走査電子顕微鏡（ＳＥＭ）により観察したところ、い
ずれの部分においても気泡形状に変形は認められなかっ
た。成形品の側面部及び底面部からそれぞれダンベル形
状の試料を打ち抜き、引っ張り強度を測定したところ、
両者の強度にはほとんど差が認められなかった。
【００３６】また、成形品に１５０ｃｃの水を入れ輪郭
部分を手で掴んで持ち上げたときの開口部の変形率を測
定したところ、変形率は２％以下と非常に小さいもので
あった。一方、比較のために従来の方法により１次発泡
したシートから作製された、発泡した輪郭部分を有する
成形品について上記と同様にして開口部の変形率を測定
したところ、変形率は３５％と非常に大きかった。
【００３７】
【発明の効果】以上詳述したように本発明の方法を用い
れば、機械的強度が高く、成形品の部分によって機械的
強度のばらつきがない熱可塑性ポリエステル樹脂発泡成
形品を製造することができ、深絞り成形にも好適に適用
できる。Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a foamed thermoplastic polyester resin article. 2. Description of the Related Art Conventionally, in order to manufacture a thermoplastic resin foam molded article, a primary foam sheet is fixed with a clamp or the like, the sheet is sandwiched between male and female heating molds, and foaming in the mold is performed in the mold. A method of obtaining a desired molded product by (secondary foaming) is generally known. [0003] In order to obtain a large number of molded products, there is also known a method in which a partition plate for pressing a contour portion of each molded product is sandwiched between a male die and a female die. (For example, JP-A-58-193123). Further, in order to produce a foamed molded article of a thermoplastic polyester resin, a foamed sheet is prepared by various known methods, and preheated until the foamed sheet is softened.
It is known to use a heating mold of a vacuum molding machine to cause heat crystallization at the same time as molding to impart heat resistance, and to use a cooling mold to make the appearance uniform (plastics). 43, No. 6, p.
6, 1992). As a method for producing a foamed sheet, a method for producing a striped thermoplastic polyester resin foamed sheet having fine bubbles using a circular die (for example, Japanese Patent Application Laid-Open No. 4-229423) is known. I have. [0005] However, in any of the conventional methods described above, since the already foamed primary foam sheet is used, even if this is strongly pressed with a clamp, a partition plate, or the like, The part does not become non-foamed.
For this reason, there was a drawback that the contour portion of the obtained molded article was weak against a lateral or upward force. In particular, when the expansion ratio of the contour portion becomes 5 times or more, insufficient mechanical strength is inevitable regardless of the shape of the molded product. Further, when a molded article such as a cup is produced by a conventional method, the sheet at the portion corresponding to the side surface of the cup is stretched at the time of molding and the bubbles are distorted into an elliptical shape. There was a problem that the target strength became non-uniform depending on the part. Further, even if deep drawing is performed by a conventional method, since the primary foamed sheet has a small elongation, the foamed sheet may not be able to withstand the stretching during the molding, and the foamed sheet may be broken. For this reason, deep drawing was difficult with the conventional method. The present invention has been made in view of such a problem, and when a foamed molded article is manufactured from a thermoplastic polyester resin sheet, the mechanical strength is high, and the mechanical strength varies depending on the molded article portion. It is an object of the present invention to provide a method which can obtain a molded article without any trouble and is suitable for deep drawing. According to the present invention, there is provided a method for producing a foamed thermoplastic polyester resin article, comprising the steps of: adding an inert gas as a foaming agent to a thermoplastic polyester resin sheet; Holding in a vacuum forming machine, pressing a pressing plate having a shape corresponding to the contour of the molded product on both surfaces of the sheet and having a hole into which a die is inserted, and a male heating die Is pressed against the sheet through a hole provided in the pressing plate, and a portion of the sheet that is in contact with the mold is selectively foamed, and the sheet is evacuated from the fine holes provided in the mold to pull the sheet. It is characterized by comprising a molding step, and a step of stopping the evacuation, separating the mold from the molded article obtained in the step, and then cooling the molded article. Hereinafter, the present invention will be described in more detail. In the method of the present invention, the thermoplastic polyester resin sheet first contains an inert gas as a foaming agent. Examples of the thermoplastic polyester resin used here include polyethylene terephthalate, polybutylene terephthalate, and various polymer alloys composed of these base resins and polycarbonate. Of these, polyethylene terephthalate is particularly preferred. [0012] The thermoplastic polyester resin includes a crystallization nucleating agent, a crystallization accelerator, a foaming nucleating agent, an antioxidant, an antistatic agent, an ultraviolet inhibitor, a pigment, a dye as long as the inherent properties of the resin are not impaired. And various additives such as lubricants. The inert gas contained in the thermoplastic polyester resin includes helium, nitrogen, carbon dioxide, argon and the like. Among these inert gases, carbon dioxide is particularly preferable because the content in the resin can be increased. In the present invention, in order to prepare a thermoplastic polyester resin sheet containing an inert gas as a foaming agent, for example, a method described in US Pat. No. 4,473,665 can be used. In this method, a thermoplastic polyester resin sheet formed into a uniform thickness by an extruder is wound into a roll, and the roll is housed in a high-pressure container and impregnated with an inert gas under high pressure. Further, for example, a method disclosed in JP-A-4-268345 can be used. In this method, a thermoplastic polyester resin containing an inert gas is injected by injecting an inert gas as a foaming agent into a thermoplastic polyester resin in a molten state in an extruder and cooling while completely suppressing foaming of the resin. A sheet is prepared. Regardless of the method used, the resin sheet has not yet been foamed at this stage. Next, the sheet containing the inert gas is held in a vacuum forming machine, and a mold having a shape corresponding to the contour portion of the molded product (the peripheral portion of the opening of the molded product) is formed on both sides of the sheet. Is pressed on a holding plate provided with a hole into which is inserted. The holding plate may be provided with only one hole, or may be provided with a plurality of holes so that a large number of molded products can be obtained. It is desirable that the pressing force of the holding plate against the sheet be 10 kg / cm 2 or more. It is necessary that the temperature of the holding plate at the time of pressure bonding be lower than the softening temperature of the resin sheet. This is because, when the temperature of the press plate becomes higher than the softening temperature of the resin sheet, foaming starts simultaneously with pressure bonding, so that a non-foamed state of the pressure-bonded portion cannot be maintained. Also, with the increase in the number of moldings,
Because the temperature of the holding plate rises due to the radiant heat of the heating mold,
Cooling is performed using a refrigerant or the like so that the pressing plate at the time of pressure bonding is always at or below the softening temperature of the resin sheet. In addition, it is permissible that the temperature of the holding plate is slightly higher than the softening temperature of the resin sheet after the pressing of the heating mold in the subsequent step. Next, a male heating mold is pressed against a resin sheet containing an inert gas through a hole provided in the holding plate, and a portion of the sheet in contact with the mold is selectively foamed. The sheet is formed into a desired shape by evacuating from the fine holes provided in the mold. At this time, conditions such as a heating temperature and a heating time by a heating mold are appropriately set according to a degree of deep drawing of a target molded article. Finally, the evacuation is stopped, the mold is separated from the molded product obtained in the above step, and the molded product is cooled.
Manufacture the desired molded product. In the method of the present invention, the both sides of an unfoamed thermoplastic polyester resin sheet containing only an inert gas as a foaming agent are pressure-bonded with a holding plate, and a male heating mold is passed through a hole provided in the holding plate. As it selectively foams the part in contact with the mold,
It is possible to obtain a molded product in which the contour portion (the peripheral portion of the opening of the molded product) pressed by the press plate is non-foamed.
Since the contour of the molded article is non-foamed, the mechanical strength is high, and deformation due to the lateral force received when grasping by hand or the top force received when wrapping the contour with another resin Very strong against In addition, it is not necessary to devise a method of turning the end portion to increase the strength of the contour portion. In the method of the present invention, since vacuum forming is carried out simultaneously with heat foaming, the thermoplastic polyester resin sheet having a large plasticizing effect undergoes elongation at the time of molding and elongation accompanying the growth of cells at the time of foaming. It can be greatly extended. For this reason, the method of the present invention is very suitable for deep drawing. In addition, since no excessive deformation force is applied to the sheet during the vacuum forming, a foam molded article having almost no deformation and collapse of the air bubbles and having no variation in mechanical strength depending on the portion can be obtained. Embodiments of the present invention will be described below. FIG. 1 is a diagram showing the configuration of a vacuum forming machine used for manufacturing a thermoplastic polyester resin foam molded article in the following examples.
A plurality of support columns 2 are respectively mounted on the upper surface and the lower surface of the vacuum forming machine 1 so as to be vertically movable.
Thus, the upper and lower holding plates 3 are supported. These holding plates 3 have a shape corresponding to the contour of the molded product, and are provided with holes into which a mold is inserted. The hole of the holding plate 3 is, for example, 2
It is provided in three rows × 3 rows, and can take six pieces. A holding table 4 is attached to the inner lower surface of the vacuum forming machine 1 so as to be vertically movable, and a male heating mold 5 is held at an upper end thereof. From a roll containing an inert gas as a foaming agent, a sheet 11 of a thermoplastic polyester resin is fed into the vacuum forming machine 1 and subjected to predetermined steps in accordance with the method of the present invention, thereby forming, for example, a cup-shaped foam. A molded article 12 is manufactured. Example 1 A polyethylene terephthalate resin (C-0312, manufactured by Unitika Ltd.) containing a crystallization nucleating agent was dried at 140 ° C. for 5 hours using a dehumidifying dryer. The resin was supplied to an extruder, melt-kneaded, extruded into a sheet having a thickness of 0.5 mm, and the polyethylene terephthalate resin sheet was wound around a roll. Next, the rolled polyethylene terephthalate resin sheet is housed in a high-pressure container, and 60 kg of a foaming agent is placed in the container.
/ Cm 2 of carbon dioxide gas. After the sheet roll was impregnated with carbon dioxide for 24 hours, it was taken out of the high-pressure container. This sheet roll was set outside the vacuum forming machine 1 as shown in FIG. The sheet 11 was sent from the winding body into the vacuum forming machine, and the support column 2 was operated to press the pressing plate 3 on both the upper and lower surfaces of the sheet 11. In this state, the holding table 4 is operated, and the male heating mold 5 heated to 240 ° C. from below is pressed against the sheet 11 through six holes provided in the holding plate 3 in two rows × three steps, The portion of the mold 11 in contact with the mold 5 was selectively foamed, and the sheet was formed by evacuating from the fine holes provided in the mold 5. Then
After the evacuation was stopped and the mold 5 was separated from the molded product, the molded product was cooled to produce a cup-shaped foam molded product 12 having an opening diameter of 2: 1 and an internal volume of 200 cc. . When the cross sections of the side and bottom portions of the obtained molded article were observed with a scanning electron microscope (SEM), no deformation was observed in the bubble shape in any of the portions. When dumbbell-shaped samples were punched from the side and bottom of the molded product, and the tensile strength was measured,
Almost no difference was found between the two. The deformation rate of the opening when 150 cc of water was poured into the molded product and the contour (the periphery of the upper opening) was grasped by hand and lifted up was measured. The deformation rate was very low at 3% or less. It was small. Comparative Example 1 The same polyethylene terephthalate resin as in Example 1 was treated in the same manner as in Example 1, and a 0.5 mm-thick polyethylene terephthalate resin sheet was wound around a roll and impregnated with carbon dioxide gas. . A sheet is passed from the obtained sheet roll into a hot air circulation type foaming furnace, heated to a sheet surface temperature of 220 ° C. and foamed, and a polyethylene terephthalate resin having fine bubbles uniformly foamed. A foam sheet was produced. The obtained polyethylene terephthalate resin foam sheet is molded using a general vacuum molding machine having a heater and a molding die, and has a ratio of opening diameter to depth of 2: 1 and an internal volume of 200 cc. A cup-shaped foam molded article was manufactured. In the obtained molded product, the thickness of the side portion was 1/3 or less of that of the bottom portion. When the cross sections of the side surface and the bottom surface of this molded product were observed with a scanning electron microscope (SEM), the bubble shape of the side surface cross section was an elliptical shape elongated flat. When a dumbbell-shaped sample was punched out from each of the side and bottom portions of the molded product and the tensile strength was measured, the strength of the side portion was very low, being 1/4 or less of that of the bottom portion. in this way,
It has been found that the strength of the side portion is reduced as a result of the side portion being thin and the bubbles contained in the side portion being deformed. Further, the deformation rate of the opening when 150 cc of water was poured into the molded product and the contour (the periphery of the upper opening) was grasped by hand and lifted up was measured. The deformation rate was 25%.
And about 8 times larger than that of Example 1. Example 2 Polyethylene terephthalate resin (trade name: SA-1206, manufactured by Unitika Ltd.)
Was dried at 140 ° C. for 5 hours using a dehumidifying dryer. This resin and 0.5% by weight of talc (trade name: Micro Ace K-1 manufactured by Nippon Talc Co., Ltd.) as a crystallization nucleating agent were supplied to an extruder and melt-kneaded. The polyethylene terephthalate resin sheet was wound into a roll. Next, the polyethylene terephthalate resin sheet roll was housed in a high-pressure container, and the container was filled with 60 kg / cm 2 of carbon dioxide gas as a foaming agent. After the sheet roll was impregnated with carbon dioxide for 24 hours, it was taken out of the high-pressure container. This sheet roll is set on the outside of the vacuum forming machine 1 as shown in FIG. 1, and the ratio of the opening diameter to the depth is 2: 1 and the internal volume is exactly the same as in the first embodiment according to the method of the present invention. A 200 cc cup-shaped foam molded product 12 was produced. When the cross sections of the side and bottom surfaces of the obtained molded product were observed by a scanning electron microscope (SEM), no deformation was observed in the bubble shape in any of the portions. When dumbbell-shaped samples were punched from the side and bottom of the molded product, and the tensile strength was measured,
Almost no difference was found between the two. The deformation rate of the opening when 150 cc of water was poured into the molded product and the contour portion was grasped by hand and lifted up was measured, and the deformation rate was as extremely small as 4% or less. On the other hand, for the purpose of comparison, when the deformation rate of the opening was measured in the same manner as above for a molded article having a foamed contour portion, which was produced from a primary foamed sheet by a conventional method, the deformation rate was 40%. It was very big. Example 3 A polybutylene terephthalate resin (trade name: 1401-X04, manufactured by Toray Industries, Inc.) was dried at 140 ° C. for 5 hours using a dehumidifying dryer. The resin was supplied to an extruder, melt-kneaded, extruded into a sheet having a thickness of 0.5 mm, and the polybutylene terephthalate resin sheet was wound around a roll. Next, the roll of polybutylene terephthalate resin sheet was housed in a high-pressure container, and the container was filled with carbon dioxide gas at 60 kg / cm 2 as a foaming agent. After the sheet roll was impregnated with carbon dioxide for 24 hours, it was taken out of the high-pressure container. This sheet roll was set on the outside of the vacuum forming machine 1 as shown in FIG. 1, and the diameter of the opening was determined in the same manner as in Example 1 except that the temperature of the heating mold was set to 200 ° C. A cup-shaped foam molded product 12 having an inner volume of 200 cc and a ratio of depth to depth of 2: 1 was produced. When the cross sections of the side and bottom surfaces of the obtained molded product were observed by a scanning electron microscope (SEM), no deformation was observed in the bubble shape in any of the portions. When dumbbell-shaped samples were punched from the side and bottom of the molded product, and the tensile strength was measured,
Almost no difference was found between the two. The deformation rate of the opening when 150 cc of water was poured into the molded product and the contour portion was grasped by hand and lifted was measured. The deformation rate was very small, 2% or less. On the other hand, for the purpose of comparison, the deformation rate of the opening was measured in the same manner as above for a molded article having a foamed contour portion, which was produced from a sheet that was primarily foamed by a conventional method, and the deformation rate was 35%. It was very big. As described in detail above, the use of the method of the present invention produces a thermoplastic polyester resin foam molded article having high mechanical strength and having no variation in mechanical strength depending on the molded article. It can be suitably applied to deep drawing.
【図面の簡単な説明】
【図１】本発明の方法の実施に用いられた真空成形機の
構成を示す図。
【符号の説明】
１…真空成形機、２…支持柱、３…押え板、４…保持
台、５…加熱金型、１１…熱可塑性ポリエステル樹脂シ
ート、１２…発泡成形品。BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing a configuration of a vacuum forming machine used for carrying out a method of the present invention. [Description of Signs] 1 ... vacuum forming machine, 2 ... support column, 3 ... holding plate, 4 ... holding table, 5 ... heating mold, 11 ... thermoplastic polyester resin sheet, 12 ... foam molded product.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 岡田 光範 東京都千代田区丸の内２丁目６番１号 古河電気工業株式会社内 (56)参考文献 特開 平３−239527（ＪＰ，Ａ) 特開 平４−268345（ＪＰ，Ａ) 特開 平６−134854（ＪＰ，Ａ) 特開 昭50−91666（ＪＰ，Ａ) 米国特許4473665（ＵＳ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) B29C 51/00 - 51/46 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Mitsunori Okada 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Inside Furukawa Electric Co., Ltd. (56) References JP-A-3-239527 (JP, A) JP-A Heihei 4-268345 (JP, A) JP-A-6-134854 (JP, A) JP-A-50-91666 (JP, A) US Patent 4,473,665 (US, A) (58) Fields investigated (Int. Cl. 7) , DB name) B29C 51/00-51/46
Claims (1)
剤として不活性ガスを含有させる工程と、前記シートを
真空成形機中に保持し、前記シートの両面に成形品の輪
郭部分に対応する形状を有し金型が挿入される穴が設け
られた押え板を圧着させる工程と、雄型の加熱金型を前
記押え板に設けられた穴を通して前記シートに圧着さ
せ、前記シートの前記金型に接した部分を選択的に発泡
させるとともに、前記金型に設けられた微細孔より真空
引きしてシートを成形する工程と、真空引きを停止し、
前記工程で得られた成形品から前記金型を離した後、成
形品を冷却する工程とを具備したことを特徴とする熱可
塑性ポリエステル樹脂発泡成形品の製造方法。(57) [Claims 1] A step of causing a thermoplastic polyester resin sheet to contain an inert gas as a foaming agent, and holding the sheet in a vacuum forming machine to form molded articles on both sides of the sheet. Pressing a holding plate having a shape corresponding to the contour of the die and having a hole into which a mold is inserted, and pressing a male heating mold against the sheet through a hole provided in the holding plate. A step of selectively foaming a portion of the sheet in contact with the mold, and a step of forming a sheet by evacuating the fine holes provided in the mold, and stopping the evacuation;
Cooling the molded article after separating the mold from the molded article obtained in the step, and manufacturing the foamed thermoplastic polyester resin article.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31855894A JP3529175B2 (en) | 1994-12-21 | 1994-12-21 | Method for producing foamed thermoplastic polyester resin product |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31855894A JP3529175B2 (en) | 1994-12-21 | 1994-12-21 | Method for producing foamed thermoplastic polyester resin product |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH08174646A JPH08174646A (en) | 1996-07-09 |
| JP3529175B2 true JP3529175B2 (en) | 2004-05-24 |
Family
ID=18100475
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP31855894A Expired - Lifetime JP3529175B2 (en) | 1994-12-21 | 1994-12-21 | Method for producing foamed thermoplastic polyester resin product |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3529175B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9296126B2 (en) * | 2003-05-17 | 2016-03-29 | Microgreen Polymers, Inc. | Deep drawn microcellularly foamed polymeric containers made via solid-state gas impregnation thermoforming |
| JP5554551B2 (en) * | 2009-11-30 | 2014-07-23 | キョーラク株式会社 | Method for producing foam molded article |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5091666A (en) * | 1973-12-17 | 1975-07-22 | ||
| US4473665A (en) * | 1982-07-30 | 1984-09-25 | Massachusetts Institute Of Technology | Microcellular closed cell foams and their method of manufacture |
| JP2551854B2 (en) * | 1990-02-16 | 1996-11-06 | 積水化成品工業株式会社 | Forming method of expanded polyethylene terephthalate sheet |
| JP3138488B2 (en) * | 1991-02-25 | 2001-02-26 | 古河電気工業株式会社 | Method for producing saturated polyester resin foam |
| JP2849513B2 (en) * | 1992-10-27 | 1999-01-20 | 積水化成品工業株式会社 | Molding mold for crystalline thermoplastic resin sheet |
-
1994
- 1994-12-21 JP JP31855894A patent/JP3529175B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH08174646A (en) | 1996-07-09 |
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