JP4252885B2

JP4252885B2 - Plug, thermoplastic resin foam sheet manufacturing apparatus, and thermoplastic resin foam sheet manufacturing method

Info

Publication number: JP4252885B2
Application number: JP2003397411A
Authority: JP
Inventors: 真司石田; 三朗藤井
Original assignee: Sekisui Kasei Co Ltd
Current assignee: Sekisui Kasei Co Ltd
Priority date: 2003-11-27
Filing date: 2003-11-27
Publication date: 2009-04-08
Anticipated expiration: 2023-11-27
Also published as: JP2005153399A

Description

本発明は、熱可塑性樹脂発泡シート製造装置に用いるプラグ、これを用いた熱可塑性樹脂発泡シート製造装置及び熱可塑性樹脂発泡シートの製造方法に関する。 The present invention relates to a plug used in a thermoplastic resin foam sheet manufacturing apparatus, a thermoplastic resin foam sheet manufacturing apparatus using the plug, and a method of manufacturing a thermoplastic resin foam sheet.

樹脂発泡シートの製造方法として良く用いられる方法のひとつに、いわゆる押出発泡成形法がある。この押出発泡成形法はポリスチレン系樹脂、ポリエステル系樹脂、ポリプロピレン系樹脂、ポリエチレン系樹脂等の熱可塑性樹脂にも適用される。 One of the methods often used as a method for producing a resin foam sheet is a so-called extrusion foam molding method. This extrusion foam molding method is also applied to thermoplastic resins such as polystyrene resins, polyester resins, polypropylene resins, and polyethylene resins.

この押出発泡成形法について簡単に説明すると、これは、押出機内で熱可塑性樹脂を発泡剤と共に溶融混合し、この溶融混合物（以下、「樹脂溶融物」と記す。）を、押出機の吐出口に取り付けた、アウトリングとコアよりなるダイの、アウトリングとコアにより形成される円環状の隙間（以下、「樹脂流路」とする。）から外部の低圧領域に押出し、この押出された発泡中間体を、冷却された円筒状のプラグの外周面に、プラグの軸方向に沿わせることにより、上記発泡中間体を延伸して環状の発泡体を形成し、この発泡体をカッターにより切り開いて発泡シートを得る方法である。ちなみにこのプラグは、マンドレル、サイジングドラムとも言われるものである。 The extrusion foam molding method will be briefly described. This is a method in which a thermoplastic resin is melted and mixed with a foaming agent in an extruder, and this molten mixture (hereinafter referred to as “resin melt”) is discharged from an extruder. The die formed of the outer ring and the core attached to the outer ring is extruded from an annular gap formed by the outer ring and the core (hereinafter referred to as “resin flow path”) to an external low pressure region. By extending the intermediate body along the axial direction of the plug along the outer peripheral surface of the cooled cylindrical plug, the foamed intermediate body is stretched to form an annular foam body, and this foam body is cut open by a cutter. This is a method for obtaining a foam sheet. By the way, this plug is also called a mandrel or sizing drum.

このプラグを備えた装置の全体構成の一例を図１の概略図に示す。図１中、符号１は第１押出機、２は第２押出機、３はダイ（サーキュラーダイ）、４は原料配合装置、５はホッパー、６は発泡剤圧入ポンプ、７はプラグ、８はカッター、９は発泡シート、１０は引取りロール、１１は発泡シートロールである。この装置の動作を簡単に説明すると、ホッパー５からタンデム型押出機の第１押出機１内に投入された樹脂と添加剤は、第１押出機１内で溶融混合されて樹脂溶融物となり、この樹脂溶融物に発泡剤圧入ポンプ６を経て発泡剤が圧入されて、樹脂溶融物と混合される。この混合物は、第２押出機２に供給され、さらに混練され、適当な温度に冷却された後、第２押出機２の吐出口に取り付けられたダイ３の樹脂流路に導かれる。そして、ダイ３の樹脂流路に導かれた溶融混合物は、ダイ３の出口（樹脂流路の出口）で任意の押出量でもって、大気中に円筒状に押出され、そして押出されると同時に発泡する。この発泡により得られた円筒状の樹脂発泡シートは、冷却用のプラグ７で冷却された後、所定箇所がカッター８によって切り裂かれ、平面状に展開されて引取りロール１０で引っ張られ、ロール状に巻き取られて、発泡シートロール１１となる。 An example of the overall configuration of an apparatus provided with this plug is shown in the schematic diagram of FIG. In FIG. 1, reference numeral 1 is a first extruder, 2 is a second extruder, 3 is a die (circular die), 4 is a raw material blending device, 5 is a hopper, 6 is a blowing agent press-fitting pump, 7 is a plug, A cutter, 9 is a foam sheet, 10 is a take-up roll, and 11 is a foam sheet roll. Briefly describing the operation of this apparatus, the resin and additive charged from the hopper 5 into the first extruder 1 of the tandem extruder are melted and mixed in the first extruder 1 to form a resin melt. A foaming agent is pressed into the resin melt through a foaming agent press-fitting pump 6 and mixed with the resin melt. This mixture is supplied to the second extruder 2, further kneaded, cooled to an appropriate temperature, and then guided to the resin flow path of the die 3 attached to the discharge port of the second extruder 2. The molten mixture guided to the resin flow path of the die 3 is extruded into the atmosphere in a cylindrical shape with an arbitrary extrusion amount at the outlet of the die 3 (the outlet of the resin flow path), and simultaneously with the extrusion. Foam. The cylindrical resin foam sheet obtained by this foaming is cooled by a cooling plug 7, then a predetermined portion is cut by a cutter 8, developed in a plane, and pulled by a take-up roll 10, and rolled. To form a foam sheet roll 11.

そして、このような押出発泡成形法による樹脂発泡シートの製造に用いるプラグとしては、平面平滑性及び熱伝導性の良好な、例えばアルミニウムのような金属材料を、ダイの樹脂流路の径より大きな径を有した円筒状に形成したものを用いる（例えば、特許文献１〜５参照）。
特公平６−２２８８９号公報特開２００１−１９１３９１号公報特公平６−２８８８９号公報特開２００１−３２８１５５号公報特開２０００−２５４９５５号公報 And as a plug used for manufacture of the resin foam sheet by such an extrusion foaming method, a metal material such as aluminum having good flatness and thermal conductivity is larger than the diameter of the resin flow path of the die. What was formed in the cylindrical shape which has a diameter is used (for example, refer patent documents 1-5).
Japanese Examined Patent Publication No. 6-22889 JP 2001-191391 A Japanese Examined Patent Publication No. 6-28889 JP 2001-328155 A JP 2000-254955 A

前述した従来技術のうち、特許文献１〜４に記載されているような従来のプラグはポリスチレン系樹脂発泡シートの製造には適していたものの、これ以外の、例えばポリエチレンテレフタレート樹脂の低倍発泡体の製造に用いようとすると、発泡シートのプラグ表面における摩擦抵抗が大きい為、シートに品質上の問題が発生していた。 Among the above-described conventional techniques, the conventional plugs described in Patent Documents 1 to 4 are suitable for the production of polystyrene resin foam sheets, but other than this, for example, a low-magnification foam of polyethylene terephthalate resin When it was going to be used for manufacturing, the frictional resistance on the plug surface of the foamed sheet was large, which caused a quality problem in the sheet.

つまり、ダイの樹脂流路から押出されたポリエチレンテレフタレート樹脂の低倍発泡体からなる発泡シートを引取りロールで引っ張ると、プラグと発泡シートの間に生じる表面摩擦による摩擦抵抗が大きく、その表面を発泡シートが滑らかにすべらない為に、発泡シートに横シマが生じてしまうのである。この横シマは以下のようにして発生する。発泡シートをある一定の力で引っ張りつづけると、ある時点で発泡シートとプラグの間に生じる表面摩擦の為に、発泡シートがプラグ表面に引っ掛かってしまい、これを引き取る事が出来なくなってしまう。そこで、一時的にではあっても、新たに余分な力を加えて発泡シートを引き取ろうとする。発泡シートの表面を滑らかなものにする為には発泡シートの厚みが一定である必要があり、厚みを一定にする為には発泡シートを一定の力で引取り続けなければならないのに、このように引き取る力に変動が生じてしまう為に、発泡シートにかかる力加減が一定でなく、その為発泡シートの厚みが部分的に薄くなり、結果として、その薄くなった部分が横シマとなってしまうのである。 In other words, when a foam sheet made of polyethylene terephthalate resin extruded from a resin flow path of a die is pulled by a take-up roll, the frictional resistance due to surface friction generated between the plug and the foam sheet is large, and the surface is Since the foam sheet does not slide smoothly, a horizontal stripe is generated in the foam sheet. This horizontal stripe occurs as follows. If the foamed sheet is pulled with a certain force, the foamed sheet is caught on the plug surface due to surface friction generated between the foamed sheet and the plug at a certain point of time and cannot be taken up. Therefore, even if temporarily, an extra force is applied to try to take off the foam sheet. In order to make the surface of the foam sheet smooth, the thickness of the foam sheet needs to be constant, and in order to make the thickness constant, the foam sheet has to be taken up with a constant force, like this The force applied to the foam sheet fluctuates, so the force applied to the foam sheet is not constant, so the thickness of the foam sheet is partially reduced. As a result, the thinned part becomes a horizontal stripe. It ends up.

また発泡シートを引き取る時に、やはりプラグとの間に生じる抵抗のため、発泡シートを真っ直ぐ引き取る事が出来ず、製品が蛇行してしまうこともある。さらに、プラグを繰り返し使用することにより、プラグ表面にアルミニウムの摩耗が生じ、その摩耗が原因で発泡シートに黒スジが生じてしまうこともある。 Also, when the foam sheet is pulled, the resistance generated between the plug and the plug cannot be pulled straight, and the product may meander. Furthermore, repeated use of the plug may cause aluminum wear on the plug surface, which may cause black streaks on the foam sheet.

また、特許文献５に記載された技術では、ポリエチレンテレフタレート樹脂の低倍発泡シートの製造も可能なように、従来のアルミニウムを用いたプラグ表面に対してアルマイト処理を行い、表面を硬質アルマイトでメッキしたプラグを用いている。これによって、発泡シートのプラグ表面における摩擦抵抗が下げられ、ポリエチレンテレフタレート樹脂の低倍発泡シートを製造する際にも、製品の横シマ、厚み変動、蛇行などの問題はある程度改善された。 In addition, in the technique described in Patent Document 5, alumite treatment is applied to the plug surface using conventional aluminum so that a low-magnification foamed sheet of polyethylene terephthalate resin can be manufactured, and the surface is plated with hard anodized. The plug is used. As a result, the frictional resistance on the plug surface of the foamed sheet was reduced, and problems such as lateral stripes, thickness fluctuations, and meandering of the product were improved to some extent when producing a low-magnification foamed sheet of polyethylene terephthalate resin.

しかしながら、特許文献５に記載された改良型のプラグを用いても、ポリスチレン系樹脂発泡シートやポリプロピレン系樹脂発泡シートの製造においてはなお課題が残されていた。
すなわち、発泡シートの横シマや蛇行により製品の品質や生産性が低下する課題が残されていた。特に、結晶性樹脂であるポリプロピレン系樹脂発泡シートの押出成形においては、発泡樹脂温度における樹脂の溶融張力が低く、金型から押し出された直後の発泡体の樹脂の引張強度が低いため、プラグ部分での発泡シートの引取り抵抗が大きいと、発泡体が切断してしまう場合があり、特に低発泡倍率で低坪量（坪量＝目付け）の発泡体が製造できないという課題があった。
また、発泡シートの外観を向上させようとして、発泡シートの気泡径を細かくしていくと、さらに引取り抵抗が大きくなる現象が見られるため、気泡を細かくして外観を向上させることができないという課題もあった。
また、特許文献５においてポリエチレンテレフタレート樹脂の低倍発泡シートの製造では抵抗削減効果のあったプラグ表面へのショットブラスト加工は、ポリプロピレン系樹脂発泡シートの製造では発泡シート表面に凹状スジを発生させるという課題が発生した。 However, even when the improved plug described in Patent Document 5 is used, problems still remain in the production of polystyrene resin foam sheets and polypropylene resin foam sheets.
In other words, there remains a problem that the quality and productivity of the product are lowered due to the horizontal stripes and meandering of the foam sheet. In particular, in extrusion molding of a polypropylene resin foam sheet that is a crystalline resin, the melt tension of the resin at the foamed resin temperature is low, and the tensile strength of the foam resin immediately after being extruded from the mold is low, so the plug portion When the take-up resistance of the foamed sheet is large, the foam may be cut, and there is a problem that a foam with a low foaming ratio and a low basis weight (basis weight = basis weight) cannot be produced.
Also, if the bubble diameter of the foam sheet is made finer in an attempt to improve the appearance of the foam sheet, a phenomenon that the take-up resistance further increases is observed, so that the appearance cannot be improved by making the bubbles finer. There were also challenges.
Further, in Patent Document 5, shot blasting on the plug surface, which has a resistance reducing effect in the production of a low-magnification foamed sheet of polyethylene terephthalate resin, is said to generate concave streaks on the foamed sheet surface in the production of a polypropylene resin foamed sheet. A problem occurred.

本発明は前記事情に鑑みてなされ、摩擦抵抗や発泡シートの収縮による引取り抵抗を減少させて、高品質のポリスチレン系樹脂発泡シートの生産性のよい製造、低発泡倍率で低坪量のポリプロピレン系樹脂発泡シートの安定した製造を可能とした熱可塑性樹脂発泡シート製造装置に用いるプラグ、これを用いた熱可塑性樹脂発泡シート製造装置及び熱可塑性樹脂発泡シートの製造方法の提供を目的とする。 The present invention has been made in view of the above circumstances, reduces the friction resistance and the take-up resistance due to the shrinkage of the foam sheet, and produces a high-quality polystyrene resin foam sheet with good productivity, low foaming ratio and low basis weight polypropylene. It is an object of the present invention to provide a plug used in a thermoplastic resin foam sheet manufacturing apparatus that enables stable production of a thermoplastic resin foam sheet, a thermoplastic resin foam sheet manufacturing apparatus using the plug, and a method for manufacturing a thermoplastic resin foam sheet.

前記目的を達成するため、本発明は、熱可塑性樹脂と発泡剤とを溶融混合して溶融混合物を押し出す押出機と、該押出機の吐出口に取り付けられたダイと、ダイから押し出された発泡中間体を外周面に沿わせて進行させながら冷却して熱可塑性樹脂発泡シートを製造するプラグとを備えた熱可塑性樹脂発泡シート製造装置に用いるプラグにおいて、プラグの外周をダイ側からシート引取り方向下流側に向けて漸次減少させた外周漸減部が設けられ、減少角度が０．０５〜０．８度、かつ外周減少率が９９．８〜９７．５％である前記外周漸減部がプラグのダイ側からシート引取り方向終端まで設けられたことを特徴とするプラグを提供する。
また本発明は、熱可塑性樹脂と発泡剤とを溶融混合して溶融混合物を押し出す押出機と、該押出機の吐出口に取り付けられたダイと、ダイから押し出された発泡中間体を外周面に沿わせて進行させながら冷却して熱可塑性樹脂発泡シートを製造するプラグとを備えた熱可塑性樹脂発泡シート製造装置に用いるプラグにおいて、プラグの外周をダイ側からシート引取り方向下流側に向けて漸次減少させた外周漸減部が設けられ、減少角度が０．８〜２．５度、かつ外周減少率が９９．１〜９７．３％である前記外周漸減部がプラグのダイ側からシート引取り方向下流側の所定位置までの間に設けられ、それよりシート引取り方向下流側はプラグの外周が一定のストレート部分とされたことを特徴とするプラグを提供する。
また本発明は、熱可塑性樹脂と発泡剤とを溶融混合して溶融混合物を押し出す押出機と、該押出機の吐出口に取り付けられたダイと、ダイから押し出された発泡中間体を外周面に沿わせて進行させながら冷却して熱可塑性樹脂発泡シートを製造するプラグとを備えた熱可塑性樹脂発泡シート製造装置に用いるプラグにおいて、
プラグの外周をダイ側からシート引取り方向下流側に向けて漸次減少させた外周漸減部が複数設けられ、一段目の外周漸減部の減少角度が０．８〜２．５度、かつ外周減少率が９９．１〜９７．３％であり、二段目の外周漸減部の減少角度が０．１〜０．６度、かつ外周減少率が９９．８〜９８．９％であることを特徴とするプラグを提供する。
また本発明のプラグにおいて、表面にフッ素樹脂被覆を有する構成とすることが好ましい。 To achieve the above object, the present invention provides an extruder for extruding a molten mixture by melt-mixing a thermoplastic resin and a foaming agent, a die attached to a discharge port of the extruder, and a foam extruded from the die. In a plug for use in a thermoplastic resin foam sheet manufacturing apparatus comprising a plug for manufacturing a thermoplastic resin foam sheet by cooling the intermediate body along the outer peripheral surface, the outer periphery of the plug is taken up from the die side. The outer periphery gradually decreasing portion gradually decreased toward the downstream side in the direction is provided , and the outer periphery gradually decreasing portion having a decrease angle of 0.05 to 0.8 degrees and an outer periphery decreasing rate of 99.8 to 97.5% is plugged. The plug is provided from the die side to the end in the sheet take-up direction .
The present invention also includes an extruder for extruding a molten mixture by melt-mixing a thermoplastic resin and a foaming agent, a die attached to a discharge port of the extruder, and a foaming intermediate extruded from the die on the outer peripheral surface. In a plug for use in a thermoplastic resin foam sheet manufacturing apparatus comprising a plug for manufacturing a thermoplastic resin foam sheet by cooling while proceeding along the periphery, the outer periphery of the plug is directed from the die side toward the downstream side in the sheet take-up direction. The outer periphery gradually decreasing portion provided gradually decreases, the decreasing angle is 0.8 to 2.5 degrees, and the outer periphery decreasing rate is 99.1 to 97.3%. A plug is provided which is provided between a predetermined position on the downstream side in the take-up direction, and the outer periphery of the plug is a constant straight portion on the downstream side in the sheet take-up direction .
The present invention also includes an extruder for extruding a molten mixture by melt-mixing a thermoplastic resin and a foaming agent, a die attached to a discharge port of the extruder, and a foaming intermediate extruded from the die on the outer peripheral surface. In a plug used for a thermoplastic resin foam sheet manufacturing apparatus, comprising a plug for manufacturing a thermoplastic resin foam sheet by cooling while advancing along,
A plurality of outer periphery gradually decreasing portions are provided in which the outer periphery of the plug is gradually decreased from the die side toward the downstream side in the sheet take-up direction , and the decrease angle of the first outer periphery gradually decreasing portion is 0.8 to 2.5 degrees and the outer periphery is decreased. The rate is 99.1 to 97.3%, the reduction angle of the outer periphery gradually decreasing portion of the second stage is 0.1 to 0.6 degrees, and the outer periphery reduction rate is 99.8 to 98.9%. Provide the featured plug .
In the plug of the present invention, it is preferable that the surface has a fluororesin coating.

また本発明は、熱可塑性樹脂と発泡剤とを溶融混合して溶融混合物を押し出す押出機と、該押出機の吐出口に取り付けられたダイと、ダイから押し出された発泡中間体を外周面に沿わせて進行させながら冷却して熱可塑性樹脂発泡シートを製造するプラグとを備えた熱可塑性樹脂発泡シート製造装置において、プラグとして本発明に係る前記プラグを備えたことを特徴とする熱可塑性樹脂発泡シート製造装置を提供する。 The present invention also includes an extruder for extruding a molten mixture by melt-mixing a thermoplastic resin and a foaming agent, a die attached to a discharge port of the extruder, and a foaming intermediate extruded from the die on the outer peripheral surface. A thermoplastic resin foam sheet manufacturing apparatus comprising a plug for producing a thermoplastic resin foam sheet by cooling while proceeding along the thermoplastic resin foam, wherein the plug according to the present invention is provided as the plug. A foam sheet manufacturing apparatus is provided.

また本発明は、押出機内で溶融混合された熱可塑性樹脂と発泡剤との溶融混合物を、前記押出機に取り付けられたダイから低圧領域に押出して発泡させ、前記発泡により得られた発泡中間体を、プラグの外周面に沿わせて進行させながら冷却して熱可塑性樹脂発泡シートを製造する熱可塑性樹脂発泡シートの製造方法において、プラグとして本発明に係る前記プラグを用いることを特徴とする熱可塑性樹脂発泡シートの製造方法を提供する。 The present invention also provides a foamed intermediate obtained by foaming a molten mixture of a thermoplastic resin and a foaming agent melt-mixed in an extruder by extruding from a die attached to the extruder into a low pressure region and foaming. In the thermoplastic resin foam sheet manufacturing method in which the thermoplastic resin foam sheet is manufactured by cooling along the outer peripheral surface of the plug to produce the thermoplastic resin foam sheet, and the plug according to the present invention is used as the plug. Provided is a method for producing a plastic resin foam sheet.

本発明によれば、特に結晶性熱可塑性樹脂、なかでもポリプロピレン系樹脂の押出発泡成形による発泡シートの製造において、発泡シートのプラグ上での収縮によるプラグ部分での発泡シートの引取り抵抗の増加を緩和することができ、低倍率発泡で低坪量のポリプロピレン系樹脂発泡シートが製造可能となる。
また外観に優れた気泡径の小さい熱可塑性樹脂発泡シートが製造可能になる。
また熱可塑性樹脂発泡シートの引取り抵抗に起因する生産性の低下を改善することができる。 According to the present invention, particularly in the production of a foam sheet by extrusion foam molding of a crystalline thermoplastic resin, in particular, a polypropylene resin, an increase in take-up resistance of the foam sheet at the plug portion due to shrinkage on the plug of the foam sheet. This makes it possible to produce a polypropylene resin foam sheet having a low magnification and a low basis weight.
Moreover, it becomes possible to produce a thermoplastic resin foam sheet having a small cell diameter and excellent in appearance.
Moreover, the productivity fall resulting from the take-up resistance of the thermoplastic resin foam sheet can be improved.

以下、図面を参照して本発明の一実施形態を説明する。
本発明の熱可塑性樹脂発泡シート製造装置は、図１に示すように構成された熱可塑性樹脂発泡シート製造装置において、ダイ３から押し出された発泡中間体を外周面に沿わせて進行させながら冷却して熱可塑性樹脂発泡シート９を形成するためのプラグ７として、プラグ７の外周をダイ３側からシート引取り方向下流側に向けて漸次減少させた外周漸減部が設けられたものを用いたことを特徴としている。 Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
The thermoplastic resin foam sheet manufacturing apparatus according to the present invention is a thermoplastic resin foam sheet manufacturing apparatus configured as shown in FIG. 1 and is cooled while a foamed intermediate body extruded from the die 3 is advanced along the outer peripheral surface. As the plug 7 for forming the thermoplastic resin foam sheet 9, a plug 7 provided with an outer peripheral gradually decreasing portion in which the outer periphery of the plug 7 is gradually decreased from the die 3 side toward the downstream side in the sheet take-up direction was used. It is characterized by that.

この熱可塑性樹脂発泡シート製造装置において、プラグ７以外の各構成要素は、従来公知の熱可塑性樹脂発泡シート製造装置の各構成要素を適宜組み合わせて用いることができ、図１に例示した熱可塑性樹脂発泡シート製造装置では、タンデム型押出機を構成する第１の押出機１及び第２の押出機２と、この第２の押出機２の吐出口に取り付けられたダイ３（サーキュラーダイ）と、第１の押出機１に熱可塑性樹脂と添加剤を供給する原料配合装置４と、この原料配合装置４からの供給原料を入れるホッパー５と、ダイ３の出口に隣接して設けられたプラグ７と、該プラグ７のシート引取り方向下流側に設けられた管状シート切開用のカッター８と、このカッター８で切開されて得られる２枚の発泡シート９にそれぞれ引取り力を加える引取りロール１０と、引き取られた発泡シート９を巻き取り発泡シートロール１１とする巻き取り機とを備えて構成されている。 In this thermoplastic resin foam sheet manufacturing apparatus, each component other than the plug 7 can be used by appropriately combining each component of a conventionally known thermoplastic resin foam sheet manufacturing apparatus. The thermoplastic resin illustrated in FIG. In the foam sheet manufacturing apparatus, a first extruder 1 and a second extruder 2 constituting a tandem type extruder, and a die 3 (circular die) attached to a discharge port of the second extruder 2, A raw material blending device 4 for feeding the thermoplastic resin and additives to the first extruder 1, a hopper 5 for feeding the raw material from the raw material blending device 4, and a plug 7 provided adjacent to the outlet of the die 3. A tubular sheet cutting cutter 8 provided on the downstream side of the plug 7 in the sheet pulling direction, and a pulling force that applies a pulling force to each of the two foam sheets 9 cut by the cutter 8 A roll 10, is constituted by a winder of the foamed sheet 9 winding foam sheet roll 11 taken off.

図２は、この熱可塑性樹脂発泡シート製造装置に用いられている本発明のプラグ７を例示する正面図である。このプラグ７は、例えばアルミニウムのような金属材料を、ダイ３の樹脂流路の径より大きな径を有した略円筒状に形成した構造になっており、その内部には図示しない冷却水流路や温度センサ等が設けられる。なお、プラグ７の縦断面形状は、円形にのみ限定されるものではなく、楕円形、長円形、角部を丸めた四角形などの形状とすることもできる。 FIG. 2 is a front view illustrating the plug 7 of the present invention used in this thermoplastic resin foam sheet manufacturing apparatus. The plug 7 has a structure in which a metal material such as aluminum is formed in a substantially cylindrical shape having a diameter larger than the diameter of the resin flow path of the die 3. A temperature sensor or the like is provided. Note that the vertical cross-sectional shape of the plug 7 is not limited to a circular shape, and may be an elliptical shape, an oval shape, a quadrangular shape with rounded corners, or the like.

図２においてプラグ７の左側がダイ３に近い方であり、プラグ７の右側はシート引取り方向下流側になっている。
本発明に係るプラグ７は、プラグ７の外周をダイ３側からシート引取り方向下流側に向けて漸次減少させた外周漸減部が設けられたことを特徴としており、この外周漸減部は、次の（Ａ）〜（Ｃ）のパターンで形成することができる。
（Ａ）プラグ７のダイ３側からシート引取り方向終端まで、一定の外周減少率を持った外周漸減部とする。
（Ｂ）プラグ７のダイ３側からシート引取り方向下流側の所定位置までの間に一定の外周減少率を持った外周漸減部を設け、それよりシート引取り方向下流側はプラグ７の外周が一定のストレート部分とする。
（Ｃ）外周漸減部を複数設け、かつこれら外周漸減部の外周減少率が異なるように形成する。 In FIG. 2, the left side of the plug 7 is closer to the die 3, and the right side of the plug 7 is on the downstream side in the sheet take-up direction.
The plug 7 according to the present invention is characterized in that an outer periphery gradually decreasing portion is provided in which the outer periphery of the plug 7 is gradually decreased from the die 3 side toward the downstream side in the sheet take-up direction. (A) to (C).
(A) The outer periphery gradually decreases from the die 3 side of the plug 7 to the end of the sheet take-up direction with a constant outer periphery reduction rate.
(B) An outer periphery gradually decreasing portion having a constant outer periphery reduction ratio is provided between the die 7 side of the plug 7 and a predetermined position on the downstream side in the sheet take-up direction. Is a constant straight part.
(C) A plurality of outer periphery gradually decreasing portions are provided, and the outer periphery gradually decreasing portions are formed so as to have different outer periphery reduction rates.

ここで、「外周減少率」とは、（外周漸減部の最小外周／外周漸減部の最大外周）×１００（単位：％）で算出される値である。
また、以下の記載において「減少角度」とは、図２おいてプラグ７の直径をＤ１からＤ２（Ｄ１＞Ｄ２）へ長さＬ１で漸減させた時のプラグの傾斜角度を次式（１）
（Ｄ１−Ｄ２）／２Ｌ１＝ｔａｎＢ
で計算し、その角度Ｂを減少角度とする。 Here, the “peripheral decrease rate” is a value calculated by (minimum outer periphery of the outer periphery gradually decreasing portion / maximum outer periphery of the outer periphery gradually decreasing portion) × 100 (unit:%).
Further, in the following description, “decreasing angle” means the inclination angle of the plug when the diameter of the plug 7 is gradually decreased from D1 to D2 (D1> D2) by the length L1 in FIG.
(D1-D2) / 2L1 = tanB
And the angle B is set as a decrease angle.

本発明に係るプラグ７において、前記（Ａ）のパターンで外周漸減部を設ける場合、外周漸減部の好ましい減少角度は０．０５〜０．８度（プラグ７が円筒状の場合）の範囲である。また外周漸減部の好ましい外周減少率は９９．８〜９７．５％（プラグ７が円筒状の場合又は円筒状でない場合）の範囲である。
プラグ７の減少角度が前記範囲より小さいか又は外周減少率が前記範囲より大きいと、外周漸減部による発泡シートの引取り抵抗の緩和効果が十分に得られず、ストレートのプラグと同等の引取り抵抗となり、発泡シートに横シマや蛇行が生じ品質や生産性が低下する。特に低倍率発泡で低坪量のポリプロピレン系樹脂発泡シートが製造できなくなる。プラグ７の減少角度が前記範囲より大きいか又は外周減少率が前記範囲より小さいと、発泡シートとプラグ７の密着性が低下し、冷却効果が低下して局部的なシート延びが発生するおそれがある。 In the plug 7 according to the present invention, when the outer periphery gradually decreasing portion is provided in the pattern (A), a preferable decrease angle of the outer periphery gradually decreasing portion is in a range of 0.05 to 0.8 degrees (when the plug 7 is cylindrical). is there. Moreover, the preferable outer periphery decreasing rate of an outer periphery gradually decreasing part is the range of 99.8 to 97.5% (when the plug 7 is cylindrical or not cylindrical).
If the reduction angle of the plug 7 is smaller than the above range or the outer peripheral reduction rate is larger than the above range, the effect of relaxing the take-up resistance of the foam sheet by the outer peripheral gradually decreasing portion cannot be sufficiently obtained, and the same take-up as that of the straight plug Resistance is caused, and horizontal fringes and meandering occur in the foam sheet, resulting in a decrease in quality and productivity. In particular, it becomes impossible to produce a polypropylene resin foam sheet with low magnification and low basis weight. If the reduction angle of the plug 7 is larger than the above range or the outer periphery reduction rate is smaller than the above range, the adhesion between the foam sheet and the plug 7 is lowered, the cooling effect is lowered, and local sheet elongation may occur. is there.

また前記（Ｂ）のパターンで一段目の外周漸減部を設ける場合又は前記（Ｃ）のパターンで二段の外周漸減部を設ける場合、一段目の外周漸減部の好ましい減少角度は０．８〜２．５度（プラグ７が円筒状の場合）の範囲である。また一段目の外周漸減部の好ましい外周減少率は９９．１〜９７．３％（プラグ７が円筒状の場合又は円筒状でない場合）の範囲である。前記（Ｃ）のパターンの場合、二段目の外周漸減部の好ましい減少角度は０．１〜０．６度（プラグ７が円筒状の場合）の範囲である。また二段目の外周漸減部の好ましい外周減少率は９９．８〜９８．９％（プラグ７が円筒状の場合又は円筒状でない場合）の範囲である。
一段目の外周漸減部のより好ましい減少角度は１．０〜２．０度（プラグ７が円筒状の場合）の範囲である。また一段目の外周漸減部の好ましい外周減少率は９８．９〜９７．９％（プラグ７が円筒状の場合又は円筒状でない場合）の範囲である。
プラグ７の減少角度が前記範囲より小さいか又は外周減少率が前記範囲より大きいと、外周漸減部による発泡シートの引取り抵抗の緩和効果が十分に得られず、ストレートのプラグと同等の引取り抵抗となり、発泡シートに横シマや蛇行が生じ品質や生産性が低下する。特に低倍率発泡で低坪量のポリプロピレン系樹脂発泡シートが製造できなくなる。プラグ７の減少角度が前記範囲より大きいか又は外周減少率が前記範囲より小さいと、発泡シートとプラグ７の密着性が低下し、冷却効果が低下して局部的なシート延びが発生するおそれがある。また二段目の外周漸減部の減少角度が一段目よりも大きいと、プラグ７前部で主に冷却された発泡シートは、プラグ後部での収縮率が小さいためプラグ７と発泡シートの密着性が悪くなり、発泡シートの幅が不安定になるおそれがある。 In the case of providing the first-stage outer periphery gradually decreasing portion in the pattern (B) or in the case of providing the second-stage outer periphery gradually decreasing portion in the pattern (C), the preferable decreasing angle of the first-stage outer periphery gradually decreasing portion is 0.8 to. The range is 2.5 degrees (when the plug 7 is cylindrical). Moreover, the preferable outer periphery decreasing rate of the outer periphery gradually decreasing part of the 1st step is the range of 99.1 to 97.3% (when the plug 7 is cylindrical or not cylindrical). In the case of the pattern (C), the preferable reduction angle of the outer peripheral gradually decreasing portion in the second stage is in the range of 0.1 to 0.6 degrees (when the plug 7 is cylindrical). Moreover, the preferable outer periphery decreasing rate of the outer periphery gradually decreasing part of the 2nd step is 99.8 to 98.9% (when the plug 7 is cylindrical or not cylindrical).
A more preferable reduction angle of the first-stage outer periphery gradually decreasing portion is in a range of 1.0 to 2.0 degrees (when the plug 7 is cylindrical). Moreover, the preferable outer periphery decreasing rate of the outer periphery gradually decreasing part of the 1st step is the range of 98.9 to 97.9% (when the plug 7 is cylindrical or not cylindrical).
If the reduction angle of the plug 7 is smaller than the above range or the outer peripheral reduction rate is larger than the above range, the effect of relaxing the take-up resistance of the foam sheet by the outer peripheral gradually decreasing portion cannot be sufficiently obtained, and the same take-up as that of the straight plug Resistance is caused, and horizontal fringes and meandering occur in the foam sheet, resulting in a decrease in quality and productivity. In particular, it becomes impossible to produce a polypropylene resin foam sheet with low magnification and low basis weight. If the reduction angle of the plug 7 is larger than the above range or the outer periphery reduction rate is smaller than the above range, the adhesion between the foam sheet and the plug 7 is lowered, the cooling effect is lowered, and local sheet elongation may occur. is there. Further, if the angle of decrease of the outer peripheral gradually decreasing portion of the second stage is larger than that of the first stage, the foam sheet mainly cooled at the front part of the plug 7 has a small shrinkage rate at the rear part of the plug, and therefore the adhesiveness between the plug 7 and the foam sheet. May worsen and the width of the foam sheet may become unstable.

この外周漸減部の漸減形状は、テーパーまたは二次曲線形状とされる。外周漸減部は一段でもよいが、特にプラグ７上での収縮率変化が大きい結晶性熱可塑性樹脂発泡シートの製造においては、該発泡シートの収縮率に合わせて多段の外周漸減部を形成することが好ましい。発泡シートの収縮率に合わせて多段の外周漸減部を形成することにより、プラグ７の全長に渡って適度な密着性とすることができる。この場合、ダイ３に近い側の外周漸減部をそれより下流側の外周漸減部よりも急角度（外周減少率が小）とすることが好ましい。この結果、発泡シートの収縮率の大きい部分での引取り抵抗を緩和することができ、全長に渡って適度な密着性とすることができる。 The gradually decreasing shape of the outer periphery gradually decreasing portion is a taper or a quadratic curve shape. The outer periphery gradually decreasing portion may be one stage, but in the production of a crystalline thermoplastic resin foam sheet having a large change in shrinkage rate on the plug 7, a multi-stage outer periphery gradually decreasing portion should be formed in accordance with the shrinkage rate of the foam sheet. Is preferred. By forming the multi-stage outer periphery gradually decreasing portion in accordance with the shrinkage rate of the foam sheet, it is possible to achieve appropriate adhesion over the entire length of the plug 7. In this case, it is preferable that the outer periphery gradually decreasing portion closer to the die 3 is steeper than the outer periphery gradually decreasing portion downstream (the outer periphery decreasing rate is smaller). As a result, it is possible to reduce the take-up resistance at the portion where the shrinkage rate of the foamed sheet is large, and it is possible to achieve appropriate adhesion over the entire length.

本発明に係るプラグ７は、その表面にフッ素樹脂被覆を設けることで、表面に沿って引き取られる発泡シートの引取抵抗をより一層減じることができる。これに用いられるフッ素樹脂としては、ポリ四フッ化エチレン（ＰＴＦＥ）、パーフルオロアルコキシ・フッ素樹脂（ＰＦＡ）、四フッ化エチレン・六フッ化プロピレン共重合体（ＦＥＰ）、エチレン四フッ化エチレン共重合体（ＥＴＦＥ）、ポリクロロ三フッ化エチレン（ＰＣＴＦＥ）、フッ化ビニリデン（ＰＶＤＦ）、フッ化ビニル（ＰＦＶ）などが挙げられ、その中でも耐熱性、耐摩耗性などに優れたポリ四フッ化エチレン樹脂が好ましい。このフッ素樹脂被覆の厚さは限定されず、またその形成方法はフッ素樹脂コーティングの分野で従来公知の各種方法により形成可能である。 The plug 7 according to the present invention can further reduce the take-up resistance of the foamed sheet taken along the surface by providing a fluororesin coating on the surface. The fluororesin used for this is polytetrafluoroethylene (PTFE), perfluoroalkoxy / fluororesin (PFA), tetrafluoroethylene / hexafluoropropylene copolymer (FEP), ethylene tetrafluoride ethylene co Polymer (ETFE), polychlorotrifluoride ethylene (PCTFE), vinylidene fluoride (PVDF), vinyl fluoride (PFV), etc. Among them, polytetrafluoroethylene excellent in heat resistance, wear resistance, etc. Resins are preferred. The thickness of the fluororesin coating is not limited and can be formed by various methods known in the art in the field of fluororesin coating.

次に、本発明に係る熱可塑性樹脂発泡シートの製造方法を説明する。
本発明の方法は、前述したように、外周をダイ３側からシート引取り方向下流側に向けて漸次減少させた外周漸減部が設けられたプラグ７を備えた図１に示す熱可塑性樹脂発泡シート製造装置を用いて好適に実施される。
本発明の方法において、原料となる熱可塑性樹脂としては、ポリスチレン系樹脂、ポリエチレン系樹脂、ポリプロピレン系樹脂、ポリエチレンテレフタレート系樹脂などの各種の熱可塑性樹脂が使用できる。特に本発明の方法では、従来法では製造が困難であった結晶性熱可塑性樹脂、特にポリプロピレン系樹脂を用い、低倍率発泡で低坪量のポリプロピレン系樹脂発泡シートを製造することができる。 Next, the manufacturing method of the thermoplastic resin foam sheet concerning this invention is demonstrated.
As described above, the method of the present invention includes the thermoplastic resin foam shown in FIG. 1 provided with the plug 7 provided with the outer periphery gradually decreasing portion whose outer periphery is gradually decreased from the die 3 side toward the downstream side in the sheet take-up direction. It is preferably implemented using a sheet manufacturing apparatus.
In the method of the present invention, various thermoplastic resins such as polystyrene resin, polyethylene resin, polypropylene resin, and polyethylene terephthalate resin can be used as the raw material thermoplastic resin. In particular, in the method of the present invention, it is possible to produce a polypropylene resin foam sheet having a low magnification and a low basis weight by using a crystalline thermoplastic resin, particularly a polypropylene resin, which is difficult to produce by the conventional method.

原料のポリプロピレン系樹脂等の熱可塑性樹脂は、添加剤と共に原料配合装置４で配合されてホッパー５から押出機に供給される。添加剤としては、例えば、気泡調整剤、酸化防止剤、金属不活性剤、難燃剤、紫外線吸収剤、架橋剤、連鎖移動剤、滑剤、可塑剤、充填材、強化材、顔料、染料、帯電防止剤などが挙げられる。 A thermoplastic resin such as a polypropylene resin as a raw material is blended together with an additive by the raw material blending apparatus 4 and supplied from the hopper 5 to the extruder. Additives include, for example, bubble regulators, antioxidants, metal deactivators, flame retardants, UV absorbers, crosslinking agents, chain transfer agents, lubricants, plasticizers, fillers, reinforcing materials, pigments, dyes, charging Examples include inhibitors.

ホッパー５からタンデム型押出機の第１押出機１内に投入された樹脂と添加剤は、第１押出機１内で溶融混合されて樹脂溶融物となり、この樹脂溶融物に発泡剤圧入ポンプ６を経て発泡剤が圧入されて、樹脂溶融物と混合される。使用される発泡剤としては、例えば、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、ヘプタンなどの脂肪族炭化水素類、シクロブタン、シクロペンタン、シクロヘキサンなどの脂環式炭化水素類、クロロジフルオロメタン、クロロエタン、ジクロロトリフルオロエタンなどのハロゲン化炭化水素類、窒素、炭酸ガス、空気などの無機ガスなどの１種又は２種以上が挙げられる。 The resin and additive charged into the first extruder 1 of the tandem type extruder from the hopper 5 are melted and mixed in the first extruder 1 to form a resin melt, and a foaming agent press-fitting pump 6 is added to the resin melt. The foaming agent is pressed through and mixed with the resin melt. Examples of the blowing agent used include aliphatic hydrocarbons such as propane, normal butane, isobutane, normal pentane, isopentane, hexane, and heptane, alicyclic hydrocarbons such as cyclobutane, cyclopentane, and cyclohexane, and chlorodifluoro. Examples thereof include one or more of halogenated hydrocarbons such as methane, chloroethane, dichlorotrifluoroethane, and inorganic gases such as nitrogen, carbon dioxide, and air.

次いでこの混合物は、第２押出機２に供給され、さらに混練され、適当な温度に冷却された後、第２押出機２の吐出口に取り付けられたダイ３の樹脂流路に導かれる。そして、ダイ３の樹脂流路に導かれた溶融混合物は、ダイ３の出口（樹脂流路の出口）で任意の押出量でもって、大気中に円筒状に押出され、そして押出されると同時に発泡する。 Next, this mixture is supplied to the second extruder 2, further kneaded, cooled to an appropriate temperature, and then guided to the resin flow path of the die 3 attached to the discharge port of the second extruder 2. The molten mixture guided to the resin flow path of the die 3 is extruded into the atmosphere in a cylindrical shape with an arbitrary extrusion amount at the outlet of the die 3 (the outlet of the resin flow path), and simultaneously with the extrusion. Foam.

この発泡により得られた円筒状の発泡シートは、冷却用のプラグ７で冷却された後、所定箇所がカッター８によって切り裂かれ、平面状に展開されて２枚の発泡シート９となる。これらの発泡シート９はそれぞれ、引取りロール１０で引っ張られ、ロール状に巻き取られて、発泡シートロール１１となる。 The cylindrical foamed sheet obtained by this foaming is cooled by a cooling plug 7, and then a predetermined portion is cut by a cutter 8 and developed into a flat shape to form two foamed sheets 9. Each of these foam sheets 9 is pulled by a take-up roll 10 and wound into a roll shape to form a foam sheet roll 11.

本発明の方法では、外周をダイ３側からシート引取り方向下流側に向けて漸次減少させた外周漸減部が設けられたプラグ７を用いたことによって、特に結晶性熱可塑性樹脂、なかでもポリプロピレン系樹脂の押出発泡成形による発泡シートの製造において、発泡シートのプラグ７上での収縮によるプラグ部分での発泡シートの引取り抵抗の増加を緩和することができ、低倍率発泡で低坪量のポリプロピレン系樹脂発泡シートが製造可能となる。
また外観に優れた気泡径の小さい熱可塑性樹脂発泡シートが製造可能になる。
また熱可塑性樹脂発泡シートの引取り抵抗に起因する生産性の低下を改善することができる。 In the method of the present invention, the use of the plug 7 provided with the outer periphery gradually decreasing portion whose outer periphery is gradually decreased from the die 3 side toward the downstream side in the sheet take-up direction, particularly a crystalline thermoplastic resin, particularly polypropylene. In the production of a foam sheet by extrusion foam molding of a resin, the increase in the take-up resistance of the foam sheet at the plug portion due to the shrinkage on the plug 7 of the foam sheet can be alleviated, and the low basis weight and low basis weight can be reduced. A polypropylene resin foam sheet can be produced.
Moreover, it becomes possible to produce a thermoplastic resin foam sheet having a small cell diameter and excellent in appearance.
Moreover, the productivity fall resulting from the take-up resistance of the thermoplastic resin foam sheet can be improved.

本発明に係る外周漸減部が設けられたプラグ（Ａ〜Ｃ）と、従来技術による外周漸減部のないストレートなプラグ（Ｄ、Ｅ）を作製し、これらを図１に示す構成の熱可塑性樹脂発泡シート製造装置に組み込んで、［１］ポリスチレン系樹脂発泡シート、［２］ポリプロピレン系樹脂発泡シートの製造をそれぞれ実施した。 The plugs (A to C) provided with the outer periphery gradually decreasing portion according to the present invention and the straight plugs (D, E) without the outer periphery gradually decreasing portion according to the prior art are produced, and these are thermoplastic resins having the configuration shown in FIG. Incorporated into a foam sheet production apparatus, [1] polystyrene resin foam sheet and [2] polypropylene resin foam sheet were produced, respectively.

・プラグＡ：図２において、Ｄ１＝６７２．５ｍｍ、Ｄ３＝６７０．５、Ｌ１＋Ｌ２＝１０００ｍｍである略円筒状で外周漸減部（減少角度Ｂ＝０．０６°、外周減少率＝９９．７％）を有する前記（Ａ）のパターンのアルミニウム製のプラグを用いた。 Plug A: In FIG. 2, D1 = 672.5 mm, D3 = 670.5, L1 + L2 = 1000 mm, substantially cylindrical, outer peripheral gradually decreasing portion (decreasing angle B = 0.06 °, outer peripheral decreasing rate = 99.7% The aluminum plug having the pattern (A) having the above structure was used.

・プラグＢ：プラグＡの表面にポリ四フッ化エチレンを被覆した。この表面処理は東邦化成社製、タフコートによって行った。 Plug B: The surface of the plug A was coated with polytetrafluoroethylene. This surface treatment was performed by Tough Coat manufactured by Toho Kasei Co., Ltd.

・プラグＣ：図２において、Ｄ１＝６８２ｍｍ、Ｄ２＝６７３ｍｍ、Ｄ３＝６７３、Ｌ１＝２１０ｍｍ、Ｌ２＝３５０ｍｍである略円筒状で前部（Ｌ１）に外周漸減部（減少角度Ｂ＝１．２３°、外周減少率＝９８．７％）を有し、後部（Ｌ２）がストレートである前記（Ｂ）のパターンのアルミニウム製のプラグ基材を作製し、その表面に硬質アルマイト処理＋ＰＴＦＥ処理を施した。この表面処理はホシ技研社製、テフロハードによって行った。 Plug C: In FIG. 2, D1 = 682 mm, D2 = 673 mm, D3 = 673, L1 = 210 mm, L2 = 350 mm, and a substantially cylindrical shape with a gradually decreasing outer periphery (reduction angle B = 1.23) at the front (L1) The outer peripheral reduction rate was 98.7%), and the plug part made of aluminum having the pattern (B) having a straight rear part (L2) was prepared, and the surface thereof was subjected to hard anodized treatment + PTFE treatment. did. This surface treatment was performed by Tefrohard made by Hoshi Giken.

・プラグＤ：図２において、Ｄ１〜Ｄ３＝６７１ｍｍ、Ｌ１＋Ｌ２＝１０００ｍｍである円筒状で外周漸減部を持たないアルミニウム製のプラグを用いた。 -Plug D: In FIG. 2, an aluminum plug having a cylindrical shape with D1 to D3 = 671 mm and L1 + L2 = 1000 mm and having no outer circumferentially decreasing portion was used.

・プラグＥ：プラグＤの表面にポリ四フッ化エチレンを被覆した。この表面処理は東邦化成社製、タフコートによって行った。 Plug E: The surface of the plug D was coated with polytetrafluoroethylene. This surface treatment was performed by Tough Coat manufactured by Toho Kasei Co., Ltd.

［１］ポリスチレン系樹脂発泡シートの製造
［実施例１］
前記プラグＡを図１に示す製造装置に組み込んだ。
ポリスチレン系樹脂として、東洋スチレン社製ＨＲＭ−２６を用い、この樹脂１００質量部に対して、気泡調整剤として、タルクを１．０質量部ドライブレンドした。この混合原料を、口径９０ｍｍ−１１５ｍｍの第１押出機及び第２押出機からなるタンデム押出機の第１押出機のホッパーに供給し、加熱溶融した後、発泡剤としてブタン（イソブタン／ノルマルブタン＝３５／６５）を樹脂溶融物１００質量部に対して３．５質量部圧入し、混練した。この混合物を引き続き第２押出機に移送して発泡適性温度まで冷却し、第２押出機先端に取り付けた口径１９０ｍｍの円筒状の押出口をもつサーキュラーダイより、１８０ｋｇ／時間の押出量で押出発泡させた。得られた円筒状発泡体を、内部が２５℃の冷却水で冷却されているプラグＡ上を沿わせて冷却するとともに、その外面をプラグＡの直径よりも大きい吹き出し口をもつ空冷装置により空気を吹き付けて冷却成形し、プラグ下流に取り付けられたカッターで切り開いて２つの連続シートとしてロール上に巻き取った。
その結果、坪量２２０ｇ／ｍ^２、厚み２．２ｍｍのポリスチレン系樹脂発泡シートを安定して製造することができた。引取り抵抗は、引取り機のモーター負荷により評価した。引取り抵抗は、張力などの力の単位で表現することが望ましいが、この力は引取り機の駆動トルクとして代用できるので、引取り機のモーターの負荷として比較できる。実施例１においてモーター負荷は１７．０Ａであった。結果を表１に示す。 [1] Production of polystyrene resin foam sheet [Example 1]
The plug A was incorporated in the manufacturing apparatus shown in FIG.
HRM-26 manufactured by Toyo Styrene Co., Ltd. was used as the polystyrene-based resin, and 1.0 part by mass of talc was dry blended as a bubble regulator with respect to 100 parts by mass of the resin. This mixed raw material is supplied to a hopper of a first extruder of a tandem extruder composed of a first extruder and a second extruder having a diameter of 90 mm to 115 mm, heated and melted, and then butane (isobutane / normal butane = 35/65) was press-fitted into 3.5 parts by mass with respect to 100 parts by mass of the resin melt and kneaded. This mixture is subsequently transferred to the second extruder and cooled to a suitable foaming temperature, and extruded and foamed at an extrusion rate of 180 kg / hour from a circular die having a cylindrical extrusion port with a diameter of 190 mm attached to the tip of the second extruder. I let you. The obtained cylindrical foam is cooled along the plug A, the inside of which is cooled with cooling water at 25 ° C., and the outer surface thereof is air-cooled by an air cooling device having an outlet larger than the diameter of the plug A. Were blown and cooled, and cut by a cutter attached downstream of the plug and wound on a roll as two continuous sheets.
As a result, a polystyrene resin foam sheet having a basis weight of 220 g / m ² and a thickness of 2.2 mm could be stably produced. The take-up resistance was evaluated by the motor load of the take-up machine. The take-up resistance is desirably expressed in units of force such as tension, but since this force can be substituted as the drive torque of the take-up machine, it can be compared as the load of the take-up machine motor. In Example 1, the motor load was 17.0A. The results are shown in Table 1.

［実施例２］
プラグＡに代えてプラグＢを用いた以外は、実施例１と同様にしてポリスチレン系樹脂発泡シートを製造した。
その結果、坪量２２０ｇ／ｍ^２、厚み２．２ｍｍのポリスチレン系樹脂発泡シートを安定して製造することができた。モーター負荷は１６．５Ａであった。結果を表１に示す。 [Example 2]
A polystyrene resin foam sheet was produced in the same manner as in Example 1 except that the plug B was used in place of the plug A.
As a result, a polystyrene resin foam sheet having a basis weight of 220 g / m ² and a thickness of 2.2 mm could be stably produced. The motor load was 16.5A. The results are shown in Table 1.

［比較例１］
プラグＡに代えてプラグＤを用いた以外は、実施例１と同様にしてポリスチレン系樹脂発泡シートを製造した。
その結果、坪量２２０ｇ／ｍ^２、厚み２．２ｍｍのポリスチレン系樹脂発泡シートを安定して製造することができたが、モーター負荷は１９．５Ａと高くなった。結果を表１に示す。 [Comparative Example 1]
A polystyrene resin foam sheet was produced in the same manner as in Example 1 except that the plug D was used instead of the plug A.
As a result, a polystyrene resin foam sheet having a basis weight of 220 g / m ² and a thickness of 2.2 mm could be stably produced, but the motor load was as high as 19.5 A. The results are shown in Table 1.

［比較例２］
プラグＡに代えてプラグＥを用いた以外は、実施例１と同様にしてポリスチレン系樹脂発泡シートを製造した。
その結果、坪量２２０ｇ／ｍ^２、厚み２．２ｍｍのポリスチレン系樹脂発泡シートを安定して製造することができたが、モーター負荷は１９．０Ａと高くなった。結果を表１に示す。 [Comparative Example 2]
A polystyrene resin foam sheet was produced in the same manner as in Example 1 except that the plug E was used instead of the plug A.
As a result, a polystyrene resin foam sheet having a basis weight of 220 g / m ² and a thickness of 2.2 mm could be stably produced, but the motor load was as high as 19.0 A. The results are shown in Table 1.

前記実施例１〜２及び比較例１〜２においてそれぞれ製造した発泡シートについて横シマの発生度合、シートロールの蛇行発生度合及びこれらの総合評価を、次の評価基準に基づいて評価した、結果を表２に示す。 About the foam sheet produced in Examples 1 and 2 and Comparative Examples 1 and 2, the degree of occurrence of horizontal stripes, the degree of meandering of sheet rolls, and their overall evaluation were evaluated based on the following evaluation criteria. It shows in Table 2.

・横シマの評価（シートの外観の評価）
製造された発泡シートの外観を目視検査し、横シマの発生度合を次の判定基準で評価した。
◎：横シマは全く見られない。（外観良好）
○：横シマはほとんど見られない。（外観良好）
△：横シマがわずかに見られる。
×：横シマがはっきり目立つ。（外観悪い）・ Evaluation of horizontal stripes (evaluation of sheet appearance)
The appearance of the manufactured foam sheet was visually inspected, and the degree of occurrence of horizontal stripes was evaluated according to the following criteria.
A: Horizontal stripes are not seen at all. (Good appearance)
○: Horizontal stripes are hardly seen. (Good appearance)
Δ: Side stripes are slightly seen.
X: Horizontal stripes are clearly noticeable. (Appearance is bad)

・巻き蛇行の評価
製造された発泡シートロール１１について、図３（ｂ）に示すように一定幅の発泡シートを巻き取った際に、発泡シートの蛇行によって生じた発泡シートロール１２の端面のシートのずれ幅を測定し、次の判定基準で評価した。
ずれ幅５ｍｍ未満：蛇行なし（評価◎：図３（ａ）参照）。
ずれ幅５〜１０ｍｍ：蛇行少ない（評価○）。
ずれ幅１０ｍｍ超：蛇行多い（評価×：図３（ｂ）参照）。 -Evaluation of winding meandering About the manufactured foaming sheet roll 11, as shown in FIG.3 (b), when winding a foam sheet of fixed width, the sheet | seat of the end surface of the foaming sheet roll 12 produced by meandering of the foaming sheet The deviation width was measured and evaluated according to the following criteria.
Deviation width of less than 5 mm: no meandering (evaluation ◎: see FIG. 3A).
Deviation width 5 to 10 mm: Less meandering (evaluation ○).
Deviation width over 10 mm: many meanders (evaluation x: see FIG. 3B).

表１，２の結果から、本発明に係る外周漸減部を有するプラグＡ，Ｂを使用した実施例１，２では、プラグを通過する発泡シートの引取り抵抗が低下することで、モーター負荷が少なくなり、製造された発泡シートの横シマ発生が減少した。また発泡シートの巻き蛇行が少なくなり、高品質の発泡シートを生産性よく製造できることがわかった。
一方、外周漸減部の無いストレートな円筒状であるプラグＤ，Ｅを使用した比較例１，２では、プラグを通過する発泡シートの引取り抵抗が上昇することで、モーター負荷が上がり、製造された発泡シートの横シマ発生が増加した。また発泡シートの巻き蛇行が多くなった。 From the results of Tables 1 and 2, in Examples 1 and 2 using the plugs A and B having the outer periphery gradually decreasing portion according to the present invention, the take-up resistance of the foam sheet passing through the plug is reduced, so that the motor load is reduced. The occurrence of horizontal stripes in the produced foam sheet was reduced. It was also found that the winding sheet meandering was reduced, and a high-quality foam sheet could be produced with high productivity.
On the other hand, in Comparative Examples 1 and 2 using straight cylindrical plugs D and E without a gradually decreasing portion, the load on the foam sheet passing through the plug is increased, which increases the motor load and is manufactured. The occurrence of horizontal stripes on the foam sheet increased. In addition, the winding meander of the foam sheet increased.

［２］ポリプロピレン系樹脂発泡シートの製造
［実施例３］
前記プラグＣを図１に示す製造装置に組み込んだ。
ポリプロピレン系樹脂として、サンアロマー社製のＰＭ６００Ａ（７５質量％）と、Ｂａｓｅｌｌ社製のＳＤ６３２（２５質量％）とを混合し、この混合樹脂１００質量部に対して、気泡調整剤として、クラリアント社製のＨＫ−７０を０．２質量部ドライブレンドした。この混合原料を、口径９０ｍｍ−１１５ｍｍの第１押出機及び第２押出機からなるタンデム押出機の第１押出機のホッパーに供給し、加熱溶融した後、発泡剤としてブタン（イソブタン／ノルマルブタン＝３５／６５）を樹脂溶融物１００質量部に対して１．０質量部圧入し、混練した。この混合物を引き続き第２押出機に移送して発泡適性温度まで冷却し、第２押出機先端に取り付けた口径１９０ｍｍの円筒状の押出口をもつサーキュラーダイより、１４０ｋｇ／時間の押出量で押出発泡させた。得られた円筒状発泡体を、内部が２５℃の冷却水で冷却されているプラグＣ上を沿わせて冷却するとともに、その外面をプラグＣの直径よりも大きい吹き出し口をもつ空冷装置により空気を吹き付けて冷却成形し、プラグ下流に取り付けられたカッターで切り開いて２つの連続シートとしてロール上に巻き取った。
その結果、坪量３００ｇ／ｍ^２、厚み０．８２ｍｍのポリプロピレン系樹脂発泡シートを安定して製造することができた。モーター負荷は１６．０Ａであった。結果を表３に示す。 [2] Production of polypropylene resin foam sheet [Example 3]
The plug C was incorporated in the manufacturing apparatus shown in FIG.
As a polypropylene resin, PM600A (75% by mass) manufactured by Sun Allomer Co., Ltd. and SD632 (25% by mass) manufactured by Basell are mixed, and 100 parts by mass of the mixed resin is manufactured by Clariant Co. HK-70 of 0.2 parts by mass was dry blended. This mixed raw material is supplied to a hopper of a first extruder of a tandem extruder composed of a first extruder and a second extruder having a diameter of 90 mm to 115 mm, heated and melted, and then butane (isobutane / normal butane = 35/65) was press-fitted into 1.0 part by mass with respect to 100 parts by mass of the resin melt and kneaded. This mixture is subsequently transferred to the second extruder and cooled to a suitable foaming temperature, and is extruded and foamed at an extrusion rate of 140 kg / hour from a circular die having a cylindrical extrusion port with a diameter of 190 mm attached to the tip of the second extruder. I let you. The obtained cylindrical foam is cooled along the plug C, the inside of which is cooled with cooling water at 25 ° C., and the outer surface thereof is air-cooled by an air cooling device having a blower outlet larger than the diameter of the plug C. Were blown and cooled, and cut by a cutter attached downstream of the plug and wound on a roll as two continuous sheets.
As a result, a polypropylene resin foam sheet having a basis weight of 300 g / m ² and a thickness of 0.82 mm could be stably produced. The motor load was 16.0A. The results are shown in Table 3.

［比較例３］
プラグＣに代えてプラグＥを用いた以外は、実施例３と同様にして発泡シートの製造を試みた。しかし、坪量３００ｇ／ｍ^２となるように設定して製造を行った結果、プラグ外面のシート引取抵抗が大きく、プラグ部分でシートが切断され、安定な製造ができなかった。結果を表３に示す。 [Comparative Example 3]
An attempt was made to produce a foam sheet in the same manner as in Example 3 except that the plug E was used instead of the plug C. However, as a result of manufacturing with the basis weight set to 300 g / m ² , the sheet take-up resistance on the outer surface of the plug was large, the sheet was cut at the plug portion, and stable manufacturing could not be performed. The results are shown in Table 3.

表３の結果より、本発明に係る外周漸減部を有するプラグＣを使用した実施例３では、プラグを通過する発泡シートの引取り抵抗が低下することで、坪量３００ｇ／ｍ^２の低坪量のポリプロピレン系樹脂発泡シートを安定して製造することができた。
一方、外周漸減部の無いストレートな円筒状であるプラグＥを使用した比較例３では、プラグを通過する発泡シートの引取り抵抗が強くなり、坪量３００ｇ／ｍ^２の低坪量のポリプロピレン系樹脂発泡シートを製造することができなかった。 From the result of Table 3, in Example 3 using the plug C which has the outer periphery gradually decreasing part which concerns on this invention, the take-up resistance of the foam sheet which passes a plug falls, and the basic weight is 300g / m < ² > low basis weight. An amount of the polypropylene resin foam sheet could be stably produced.
On the other hand, in the comparative example 3 using the plug E which is a straight cylindrical shape without a gradually decreasing portion on the outer periphery, the take-up resistance of the foam sheet passing through the plug is increased, and a low basis weight polypropylene system having a basis weight of 300 g / m ^2. A resin foam sheet could not be produced.

本発明の熱可塑性樹脂発泡シート製造装置の一例を示す構成図である。It is a block diagram which shows an example of the thermoplastic resin foam sheet manufacturing apparatus of this invention. 本発明のプラグの一例を示す正面図である。It is a front view which shows an example of the plug of this invention. 本発明の実施例に係る巻き蛇行の測定方法を説明するための図であり、（ａ）は蛇行のない発泡シートロールの斜視図、（ｂ）は蛇行の有る発泡シートロールの側面図である。It is a figure for demonstrating the measuring method of the winding meander which concerns on the Example of this invention, (a) is a perspective view of the foam sheet roll without meandering, (b) is a side view of the foam sheet roll with meandering .

Explanation of symbols

１…第１押出機、２…第２押出機、３…ダイ、４…原料配合装置、５…ホッパー、６…発泡剤圧入ポンプ、７…プラグ、８…カッター、９…発泡シート、１０…引取りロール、１１，１２…発泡シートロール。
DESCRIPTION OF SYMBOLS 1 ... 1st extruder, 2 ... 2nd extruder, 3 ... Die, 4 ... Raw material compounding apparatus, 5 ... Hopper, 6 ... Foaming agent press injection pump, 7 ... Plug, 8 ... Cutter, 9 ... Foam sheet, 10 ... Take-up rolls, 11, 12, foam sheet rolls.

Claims

An extruder for extruding the molten mixture by melting and mixing the thermoplastic resin and the foaming agent, a die attached to the discharge port of the extruder, and a foaming intermediate extruded from the die are allowed to travel along the outer peripheral surface. In the plug used for the thermoplastic resin foam sheet manufacturing apparatus provided with a plug for producing a thermoplastic resin foam sheet by cooling while
An outer periphery gradually decreasing portion is provided in which the outer periphery of the plug is gradually decreased from the die side toward the downstream side in the sheet take-up direction , the reduction angle is 0.05 to 0.8 degrees, and the outer periphery reduction rate is 99.8 to 97. 5. A plug characterized in that the outer peripheral gradually decreasing portion of 5% is provided from the die side of the plug to the end in the sheet take-up direction .

An extruder for extruding the molten mixture by melting and mixing the thermoplastic resin and the foaming agent, a die attached to the discharge port of the extruder, and a foaming intermediate extruded from the die are allowed to travel along the outer peripheral surface. In the plug used for the thermoplastic resin foam sheet manufacturing apparatus provided with a plug for producing a thermoplastic resin foam sheet by cooling while
An outer periphery gradually decreasing portion is provided in which the outer periphery of the plug is gradually decreased from the die side toward the downstream side in the sheet take-up direction, the reduction angle is 0.8 to 2.5 degrees, and the outer periphery reduction rate is 99.1 to 97. the outer circumferential tapering portion is 3% in between the die side of the plug to a predetermined position of the sheet pulling direction downstream side, the downstream side it from the sheet take-off the outer periphery of the plug is a fixed straight portion Plug characterized by that .

An extruder for extruding the molten mixture by melting and mixing the thermoplastic resin and the foaming agent, a die attached to the discharge port of the extruder, and a foaming intermediate extruded from the die are allowed to travel along the outer peripheral surface. In the plug used for the thermoplastic resin foam sheet manufacturing apparatus provided with a plug for producing a thermoplastic resin foam sheet by cooling while
Periphery tapering portion gradually decreased toward the outer periphery of the plug in a sheet drawing direction downstream from the die side is provided with a plurality of, decrease the angle of the outer peripheral tapering portion of the first stage is 0.8 to 2.5 degrees, and the outer periphery decreases The rate is 99.1 to 97.3%, the reduction angle of the outer periphery gradually decreasing portion of the second stage is 0.1 to 0.6 degrees, and the outer periphery reduction rate is 99.8 to 98.9%. Features a plug.

The plug according to any one of claims 1 to 3 , wherein the surface has a fluororesin coating.

An extruder for extruding the molten mixture by melting and mixing the thermoplastic resin and the foaming agent, a die attached to the discharge port of the extruder, and a foaming intermediate extruded from the die are allowed to travel along the outer peripheral surface. In a thermoplastic resin foam sheet manufacturing apparatus comprising a plug for cooling and manufacturing a thermoplastic resin foam sheet while
A thermoplastic resin foam sheet manufacturing apparatus comprising the plug according to any one of claims 1 to 4 as a plug.

The molten mixture of the thermoplastic resin and the foaming agent melt-mixed in the extruder is extruded from a die attached to the extruder into a low-pressure region and foamed, and the foamed intermediate obtained by the foaming is expanded to the outer periphery of the plug. In the method for producing a thermoplastic resin foam sheet, which is cooled while proceeding along the surface to produce a thermoplastic resin foam sheet,
A method for producing a thermoplastic resin foam sheet, wherein the plug according to any one of claims 1 to 4 is used as the plug.