JP4049301B2

JP4049301B2 - Twisted tie

Info

Publication number: JP4049301B2
Application number: JP2002007099A
Authority: JP
Inventors: 秀樹鈴木; 美智子真貝
Original assignee: Shin Etsu Polymer Co Ltd
Current assignee: Shin Etsu Polymer Co Ltd
Priority date: 2002-01-16
Filing date: 2002-01-16
Publication date: 2008-02-20
Anticipated expiration: 2022-01-16
Also published as: JP2003205565A

Description

【０００１】
【発明の属する技術分野】
本発明は、成形シート、具体的には、パン、煎餅、焼き菓子、麺類等の食品用包装袋の袋口封絨、包装容器の装飾包装、植木の添え木の結束、電気コードの結束等に用いる捻じり結束紐及びマスクの鼻形固定部材等として使用される成形シートに関するものである。
【０００２】
【従来技術】
従来、捻じり結束紐やマスクの鼻形固定部材等として使用される成形シートは、芯材と被覆材を貼り合わせて、芯材を被覆材で一体的に挟持かつ被覆した構造を有している。一般的に、芯材には針金が使用され、被覆材には基材の表面に熱融着性フィルムを積層したものが使用されている。
このような従来の成形シートは、芯材に針金を使用しているため、食品製造工程において、金属探知器に感知されてしまい、そのため、食品製造工程では使用することができないという問題点があった。また、電気及び電子製品に、従来の成形シートを使用すると、電気的な短絡を生じる虞があった。そこで、これらの問題点を解消するため、芯材に合成樹脂等の非金属を用いた成形シートが提案されている。
【０００３】
しかしながら、芯材に合成樹脂を用いた従来の成形シートは、芯材が針金の成形シートとは異なり、物品を結束したり、固定したりする場合に、形状が安定せず、形状保持能力が十分ではなかった。
また、合成樹脂からなる芯材は、その特性上、長手方向に配向しやすく、捻じり結束時に、繊維状に裂けたり、毛羽が生じたりする。そのため、芯材に合成樹脂を用いた従来の成形シートでは、捻じり結束時の結束性が低下してしまい、また、繰り返し捻じり使用することができなかった。さらに、芯材が合成樹脂からなる従来の成形シートでは、自動結束機により安定して結束することができないという不具合も生じていた。
【０００４】
【発明が解決しようとする課題】
本発明は、前記問題点を解決するものであり、具体的には、従来の針金を芯材とした成形シートと比べて遜色のない結束性、繰返し使用性及び形状保持性を有し、自動結束機により安定して結束することができる、合成樹脂を芯材とした成形シートを提供することを課題とする。
【０００５】
【課題を解決するための手段】
本発明者らは、かかる課題を解決するために、鋭意検討した結果、芯材を構成する熱可塑性樹脂のビカット軟化点を、被覆材の熱融着性フィルムを構成する熱可塑性樹脂のビカット軟化点よりも低くすること、及び芯材の断面形状を真円以外の任意の断面形状とすることが、上記課題を解決する上で、極めて有効であることを発見し、かかる知見に基づき、本発明を完成するに至った。
【０００６】
すなわち、本発明は、熱可塑性樹脂からなる熱融着性フィルムを基材の表面に積層した被覆材と熱可塑性樹脂からなる芯材より構成され、該熱融着性フィルムで該芯材を一体的に挟持かつ被覆してなる帯状の成形シートであって、該芯材を構成する熱可塑性樹脂は、該熱融着性フィルムを構成する熱可塑性樹脂よりも低いビカット軟化点をもち、該芯材の断面形状が真円以外の形状であることを特徴とする成形シートである。
【０００７】
【発明の実施の形態】
以下、図面を参照しつつ、本発明について詳述する。
本発明の成形シートは、熱融着性フィルムを基材の表面に積層した被覆材と芯材より構成される。図１(ａ)〜（ｆ）は、本発明の成形シートの例を示した断面説明図で、１は被覆材、２は芯材を表す。
本発明の成形シートは、芯材２を少なくとも１枚の被覆材１で被覆、挟持一体化して、図１に示したような形状に成形したものである。本発明の成形シートの態様として、例えば、被覆材を１枚とした場合は、芯材の周囲を覆うように、被覆材の熱融着性フィルムと芯材を貼り合わせて、芯材を被覆材で挟持、一体化した成形シートが例示される(図１(ａ)、(ｂ)、（ｃ))。また、例えば、被覆材を２枚とした場合は、それぞれの被覆材の熱融着性フィルム同志を貼り合わせて、それらの間に配置した芯材を被覆材で挟持、一体化した成形シートが例示される(図１(ｄ)、(ｅ)、（ｆ）)。
【０００８】
図２は本発明の成形シートを構成する被覆材の一例を示した断面説明図で、３は被覆材、４は基材、５は熱融着性フィルムである。
本発明を構成する被覆材３の基材４としては、通常、▲１▼ポリエチレン、ポリエチレンテレフタレート、ポリプロピレン、ポリエステル、ポリアミド、ポリウレタン、ポリカーボネート、ポリスチレン等の合成樹脂からなるフィルム及びこれらにアルミニウム等の非鉄金属蒸着層を設けたもの、▲２▼ポリプロピレン、ポリエチレン、レーヨン、パルプ及びこれらの混紡からなる坪量10〜100ｇ／ｍ²、好ましくは30〜60ｇ／ｍ²の不織布、▲３▼合成紙、和紙等の紙及びこれらにポリエチレン等の合成樹脂をラミネート加工したものが適宜使用される。
基材４の厚さは、一般に、５〜50μｍ、好ましくは10〜30μｍである。
【０００９】
本発明を構成する被覆材３の熱融着性フィルム５としては、通常、低密度ポリエチレン、直鎖状低密度ポリエチレン、高密度ポリエチレン、エチレン酢酸ビニル共重合樹脂、ポリプロピレン、ポリウレタン、熱可塑性ポリエステル、ポリアミド、スチレン系ブロックコポリマー、エチレンアクリル酸共重合樹脂、無水マレイン酸グラフトポリエチレン、無水マレイン酸グラフトポリオレフィン樹脂など及びこれらの混合物が適宜使用される。
熱融着性フィルム５の厚さは、一般に、５〜50μｍ、好ましくは10〜30μｍである。
【００１０】
本発明を構成する被覆材３の製造方法は、特に限定されないが、例えば、基材４と熱融着性フィルム５の各成分を、押出機に供給して溶融混練した後、Ｔ−ダイによる押出ラミネーション法等により製膜する公知の製膜方法が挙げられる。
【００１１】
本発明を構成する芯材２としては、通常、低密度ポリエチレン、直鎖状低密度ポリエチレン、高密度ポリエチレン、エチレン酢酸ビニル共重合樹脂、ポリプロピレン、ポリウレタン、熱可塑性ポリエステル、ポリアミド、スチレン系ブロックコポリマー、アクリル樹脂、エチレンアクリル酸共重合樹脂、無水マレイン酸グラフトポリエチレン、無水マレイン酸グラフトポリオレフィン樹脂及びこれらの混合物が適宜使用される。
さらに、上記芯材には、結束性及び形状保持性を向上させるため、炭酸カルシウム、酸化チタン、タルク、シリカ等の無機充填材を混合してもよい。
【００１２】
本発明の成形シートでは、芯材２は、真円以外の任意の断面形状を有するものに限定される。芯材の断面形状の例としては、図３(ａ)〜(ｈ)に示した形状が挙げられる。芯材の断面形状が真円である場合は、芯材に使用される合成樹脂の特性から、成形シートの形状保持能力、捻じり結束時の結束力、繰り返し捻じり使用性を得ることが困難となり、本発明の目的を達成することができない。
芯材の断面形状としては、長円形、多角形、湾曲形、不定形などの形状を、芯材を構成する素材に応じて適宜選択することができるが、成形時における形状の賦形性及び上記した本発明の目的の達成には、図３(ａ)〜(ｄ)に示したような長円形及び不定形が好ましい。
【００１３】
芯材の断面寸法は、任意に選択することができるが、実用上、その断面積は0.10〜1.00 cｍ²の範囲が好ましく、さらには0.15〜0.70 cｍ²の範囲が好ましい。芯材の断面積が、0.10 cｍ²よりも小さいと、芯材の強度が得られず、結束力が不十分となり、一方、1.00 cｍ²よりも大きいと、芯材の強度が高くなりすぎて、結束しにくくなる不具合が生じる。
【００１４】
本発明の成形シートを作製するには、被覆材の熱融着性フィルムの表面に芯材を加熱加圧融着して貼り合わせて、被覆材で該芯材を挟持、一体化すればよく、例えば、▲１▼所望する断面形状部を有するロール等を備えた加熱ラミネートロールで芯材と被覆材とを加熱溶融して、熱融着性フィルムの表面に芯材を加熱加圧融着する際に、加熱溶融しつつ連続的に芯材を加圧成形して賦形し、被覆材で該芯材を挟持、一体化する方法、あるいは、▲２▼溶融押出成形法で所望する断面形状に予め成形加工して賦形された芯材を準備しておき、加熱ラミネートロールで連続的に被覆材で該芯材を挟持、一体化する方法が選択できる。
【００１５】
本発明の成形シートでは、芯材を構成する熱可塑性樹脂は、熱融着性フィルムを構成する熱可塑性樹脂よりも低いビカット軟化点をもつように、熱融着性フィルムと芯材を構成する熱可塑性樹脂を選択する必要がある。熱融着性フィルムを構成する熱可塑性樹脂のビカット軟化点が、芯材を構成する熱可塑性樹脂のビカット軟化点よりも低いと、上記▲１▼の成形シートの作製方法において、芯材を所望の形状に賦形するために、熱融着性フィルムのシール温度以上に加熱した場合に、熱融着性フィルムが過度に溶融してしまい、熱融着性フィルムと芯材を貼り合わせる際に加える圧力により、熱融着性フィルムが基材からはみ出すとともに、熱融着性フィルムが極端に薄くなりシール性が低下して、芯材を挟持、一体化することが困難になる。
また、上記▲２▼の成形シートの作製方法においても、芯材の断面形状に基材が追従して、芯材と熱融着性フィルムとの間に空隙が生じないように挟持、一体化させることが、同様の理由から困難になる。
さらに、芯材が高結晶性で配向しやすい合成樹脂で構成されている場合、熱融着性フィルムを構成する熱可塑性樹脂のビカット軟化点が、芯材を構成する熱可塑性樹脂のビカット軟化点よりも高いと、上記した▲１▼、▲２▼の方法で成形シートを作製した場合、芯材の表面層が再溶融して配向性が緩和されて、曲げ等に対する耐久性が向上する効果が得られるが、熱融着性フィルムを構成する熱可塑性樹脂のビカット軟化点が、芯材を構成する熱可塑性樹脂のビカット軟化点よりも低いと、かかる効果が得られなくなる。
【００１６】
熱融着性フィルムと芯材を構成する熱可塑性樹脂のビカット軟化点の温度差は、５℃以上、好ましくは10℃以上あれば、成形加工上の上記問題は完全に解消され、本発明の目的とする成形シートが得られる。
また、芯材が複数の熱可塑性樹脂を混合したものである場合は、その中で最高のビカット軟化点が、熱融着性フィルムを構成する熱可塑性樹脂のビカット軟化点よりも低いことが必要である。
ビカット軟化点の測定（JIS K 7206）は、ビカット軟化点試験機に、厚さ３〜6.4mm、面積10×10 mm以上の試験片をおき、試験片の上から針で荷重を加え、昇温していって、針が１mmの深さまで試験片中に入ったときの温度を測定することにより行う。このとき、針は長さ３mm、断面１mmの円柱形で、試験片に接する面は平らであり、加える荷重は、1000〜1050ｇで、昇温速度は、50±５℃／hrである。
【００１７】
【実施例】
表１（実施例、No.１〜８）、表２(比較例、No.９〜11）に示す樹脂構成にしたがって、表１、２に示す断面形状を有する芯材を押出成形法により成形し、該芯材と被覆材を貼り合わせることにより、図１（ｄ）に示した成形シートを得た。なお、表１、２中、PETはポリエチレンテレフタレート、LDPEは低密度ポリエチレン、LLDPEは直鎖状低密度ポリエチレン、PPはポリプロピレン、HDPEは高密度ポリエチレンを表す。また、基材の厚さは、25μｍ、熱融着性フィルムの厚さは、25μｍとした。
次に、得られた成形シートについて、▲１▼結束性、▲２▼繰り返し結束、▲３▼形状保持、▲４▼自動結束機による結束性に関する評価を、以下の方法で行った。
▲１▼結束性：成形シートを手で３回捻じり、図４（ａ）に示すように二重螺旋状態に結束されたものを合格とした。一方、図４（ｂ)のように片螺旋状態に結束されたものを不合格とした。
▲２▼繰返し結束：手による成形シートの３回捻じりと捻じり開放を１サイクルとして、３サイクル繰り返した後に結束した際に、被覆材と芯材の剥離及び芯材の破損が生じないものを合格、被覆材と芯材の剥離又は芯材の破損が生じたものを不合格とした。
▲３▼形状保持：成形シートを手で３回捻じり結束した際に、図４（ａ)に示したように捻じり状態が５分間保持されたものを合格とし、図４（ｃ)に示したように結束状態が緩んだものを不合格とした。また、図５に示したように、長さ100mmの成形シートを端から長さ50 mmの所で、曲げ角度θ（曲げ角度θ≧20°）だけ曲げて、１秒間保持した後、その保持を開放し、開放時の曲げ角度θ'を測定した。その結果、θ−θ'≦５°の状態を保持したものを合格、θ−θ'＞５°であるものを不合格とした。
▲４▼自動結束機による結束性：自動結束機FT−40（ニューロング社製、商品名）を用いて菓子袋を結束し、結束できたものを合格とした。なお、結束状態は上記した二重螺旋状態を合格とした。
【００１８】
上記評価の結果を表３に示す。表３からわかるように、本発明の成形シートは、▲１▼結束性、▲２▼繰り返し結束、▲３▼形状保持、▲４▼自動結束機による結束性についてのいずれの評価においても、良好な結果が得られた。
【００１９】
【表１】

【００２０】
【表２】

【００２１】
【表３】

【００２２】
【発明の効果】
本発明によれば、優れた結束性、繰返し使用性及び形状保持性を有し、自動結束機により安定して結束することができる、合成樹脂を芯材とした成形シートを得ることができ、その産業上の利用価値はきわめて高い。
【図面の簡単な説明】
【図１】本発明の成形シートの断面説明図であり、（ａ）〜（ｃ）は被覆材が１枚の場合、（ｄ）〜（ｆ）は被覆材が２枚の場合を示す。
【図２】被覆材の断面説明図である。
【図３】芯材の断面説明図であり、（ａ）〜（ｈ）は芯材の各種断面形状を示す。
【図４】結束状態及び形状保持に関する評価方法の説明図である。
【図５】形状保持に関する評価方法の説明図である。
【符号の説明】
１、３…被覆材
２…芯材
４…基材
５…熱融着性フィルム[0001]
BACKGROUND OF THE INVENTION
The present invention is a molded sheet, specifically, a bag seal for food packaging bags such as bread, rice crackers, baked confectionery, noodles, decorative packaging for packaging containers, binding of planted splints, binding of electric cords, etc. The present invention relates to a molded sheet used as a twisted binding string and a nose-shaped fixing member for a mask.
[0002]
[Prior art]
Conventionally, a molded sheet used as a twisted binding string or a nose-shaped fixing member for a mask has a structure in which a core material and a covering material are bonded together, and the core material is integrally sandwiched and covered with the covering material. Yes. Generally, a wire is used for the core material, and a coating material in which a heat-fusible film is laminated on the surface of the base material is used.
Since such a conventional molded sheet uses a wire as a core material, it is perceived by a metal detector in the food manufacturing process, and therefore cannot be used in the food manufacturing process. It was. In addition, when conventional molded sheets are used for electrical and electronic products, there is a risk of electrical shorting. Therefore, in order to solve these problems, a molded sheet using a non-metal such as a synthetic resin as a core material has been proposed.
[0003]
However, the conventional molded sheet using synthetic resin as the core material is different from the molded sheet of the core material in that the shape is not stable when the articles are bound or fixed, and the shape retention ability is not good. It was not enough.
In addition, the core material made of synthetic resin is easily oriented in the longitudinal direction due to its characteristics, and when twisted and bound, the core material is torn into fibers or fluffed. Therefore, in the conventional molded sheet using a synthetic resin as the core material, the bundling property at the time of twisting and binding is lowered, and the twisting cannot be used repeatedly. Furthermore, the conventional molded sheet whose core material is made of synthetic resin has a problem that it cannot be stably bound by an automatic binding machine.
[0004]
[Problems to be solved by the invention]
The present invention solves the above-mentioned problems. Specifically, the present invention has a binding property, repetitive useability, and shape retention that are inferior to those of a conventional molded sheet having a wire as a core material, and is automatic. It is an object of the present invention to provide a molded sheet using a synthetic resin as a core material that can be stably bound by a binding machine.
[0005]
[Means for Solving the Problems]
In order to solve such problems, the present inventors have intensively studied. As a result, the Vicat softening point of the thermoplastic resin constituting the core material is determined by the Vicat softening of the thermoplastic resin constituting the heat-fusible film of the coating material. It has been found that it is extremely effective to solve the above problems by making the cross-sectional shape lower than the point and making the cross-sectional shape of the core material any cross-sectional shape other than a perfect circle. The invention has been completed.
[0006]
That is, the present invention comprises a coating material in which a heat-fusible film made of a thermoplastic resin is laminated on the surface of a substrate and a core material made of a thermoplastic resin, and the core material is integrated with the heat-fusible film. The thermoplastic resin constituting the core material has a lower Vicat softening point than the thermoplastic resin constituting the heat-fusible film, and is formed by sandwiching and covering the core. The molded sheet is characterized in that the cross-sectional shape of the material is a shape other than a perfect circle.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings.
The molded sheet of the present invention is composed of a coating material in which a heat-fusible film is laminated on the surface of a base material and a core material. 1A to 1F are cross-sectional explanatory views showing examples of the molded sheet of the present invention, where 1 is a covering material, and 2 is a core material.
The molded sheet of the present invention is formed by covering and interposing a core material 2 with at least one coating material 1, and forming into a shape as shown in FIG. As an aspect of the molded sheet of the present invention, for example, when the number of the coating materials is one, the core material is coated by bonding the heat-fusible film of the coating material and the core material so as to cover the periphery of the core material. Examples of the molded sheet are sandwiched and integrated with a material (FIGS. 1A, 1B, and 1C). For example, when the number of the covering materials is two, a molded sheet in which the heat-fusible films of the respective covering materials are bonded together, and the core material disposed between them is sandwiched between the covering materials and integrated. It is illustrated (FIGS. 1 (d), (e), (f)).
[0008]
FIG. 2 is an explanatory cross-sectional view showing an example of a covering material constituting the molded sheet of the present invention. 3 is a covering material, 4 is a base material, and 5 is a heat-fusible film.
As the base material 4 of the covering material 3 constituting the present invention, (1) a film made of a synthetic resin such as (1) polyethylene, polyethylene terephthalate, polypropylene, polyester, polyamide, polyurethane, polycarbonate, polystyrene, and non-ferrous such as aluminum ( ² ) Nonwoven fabric having a basis weight of 10 to 100 g / m ² , preferably 30 to 60 g / m ² , made of polypropylene, polyethylene, rayon, pulp and a blend of these, (3) synthetic paper, Paper such as Japanese paper and those obtained by laminating a synthetic resin such as polyethylene are appropriately used.
The thickness of the substrate 4 is generally 5 to 50 μm, preferably 10 to 30 μm.
[0009]
As the heat-fusible film 5 of the covering material 3 constituting the present invention, usually, low density polyethylene, linear low density polyethylene, high density polyethylene, ethylene vinyl acetate copolymer resin, polypropylene, polyurethane, thermoplastic polyester, Polyamide, styrenic block copolymer, ethylene acrylic acid copolymer resin, maleic anhydride grafted polyethylene, maleic anhydride grafted polyolefin resin, and the like, and mixtures thereof are appropriately used.
The thickness of the heat-fusible film 5 is generally 5 to 50 μm, preferably 10 to 30 μm.
[0010]
Although the manufacturing method of the coating | covering material 3 which comprises this invention is not specifically limited, For example, after supplying each component of the base material 4 and the heat-fusible film 5 to an extruder and melt-kneading, it is T-die. A known film forming method for forming a film by an extrusion lamination method or the like can be used.
[0011]
As the core material 2 constituting the present invention, usually, low density polyethylene, linear low density polyethylene, high density polyethylene, ethylene vinyl acetate copolymer resin, polypropylene, polyurethane, thermoplastic polyester, polyamide, styrenic block copolymer, Acrylic resins, ethylene acrylic acid copolymer resins, maleic anhydride grafted polyethylene, maleic anhydride grafted polyolefin resins, and mixtures thereof are used as appropriate.
Furthermore, an inorganic filler such as calcium carbonate, titanium oxide, talc, or silica may be mixed with the core material in order to improve the binding property and shape retention.
[0012]
In the molded sheet of the present invention, the core material 2 is limited to one having an arbitrary cross-sectional shape other than a perfect circle. Examples of the cross-sectional shape of the core material include the shapes shown in FIGS. When the cross-sectional shape of the core material is a perfect circle, it is difficult to obtain the shape retention ability of the molded sheet, the binding force during twist binding, and the repeated twist use due to the characteristics of the synthetic resin used for the core material. Thus, the object of the present invention cannot be achieved.
As the cross-sectional shape of the core material, an oval, a polygon, a curved shape, an indeterminate shape, and the like can be appropriately selected according to the material constituting the core material. In order to achieve the object of the present invention described above, an oval shape and an indefinite shape as shown in FIGS. 3 (a) to 3 (d) are preferable.
[0013]
Cross-sectional dimension of the core material may be selected arbitrarily, practically, the cross-sectional area is preferably in the range of 0.10 to 1.00 cm ^2, more preferably in the range of 0.15 to 0.70 cm ^2. If the cross-sectional area of the core material is smaller than 0.10 cm ² , the strength of the core material cannot be obtained and the binding force becomes insufficient. On the other hand, if the cross-sectional area is larger than 1.00 cm ² , the strength of the core material becomes too high. Inconvenience that makes it difficult to bind.
[0014]
In order to produce the molded sheet of the present invention, the core material may be bonded to the surface of the heat-fusible film of the covering material by heating and pressing, and the core material is sandwiched and integrated with the covering material. For example, (1) a core material and a covering material are heated and melted with a heat laminating roll provided with a roll having a desired cross-sectional shape portion, and the core material is heated and pressure-bonded to the surface of the heat-fusible film. In this process, the core material is continuously formed by pressure forming while being melted by heating, and the core material is sandwiched and integrated with a coating material, or (2) a desired cross section by melt extrusion molding A method can be selected in which a core material that has been shaped and shaped in advance is prepared, and the core material is sandwiched and integrated with a covering material continuously with a heating laminate roll.
[0015]
In the molded sheet of the present invention, the thermoplastic resin constituting the core material constitutes the heat-fusible film and the core material so as to have a lower Vicat softening point than the thermoplastic resin constituting the heat-fusible film. It is necessary to select a thermoplastic resin. When the Vicat softening point of the thermoplastic resin constituting the heat-fusible film is lower than the Vicat softening point of the thermoplastic resin constituting the core material, the core material is desired in the method for producing a molded sheet of (1) above. When it is heated above the sealing temperature of the heat-fusible film, the heat-fusible film will melt excessively, and when the heat-fusible film and the core material are bonded together Due to the applied pressure, the heat-fusible film protrudes from the base material, and the heat-fusible film becomes extremely thin and the sealing performance is lowered, making it difficult to sandwich and integrate the core material.
Also, in the method for producing the molded sheet of (2) above, the base material follows the cross-sectional shape of the core material, and is sandwiched and integrated so that no gap is generated between the core material and the heat-fusible film. For the same reason.
Furthermore, when the core material is composed of highly crystalline and easily oriented synthetic resin, the Vicat softening point of the thermoplastic resin constituting the heat-fusible film is the Vicat softening point of the thermoplastic resin constituting the core material. Is higher, the surface layer of the core material is remelted and the orientation is relaxed when the molded sheet is produced by the above methods (1) and (2), thereby improving the durability against bending and the like. However, when the Vicat softening point of the thermoplastic resin constituting the heat-fusible film is lower than the Vicat softening point of the thermoplastic resin constituting the core material, such an effect cannot be obtained.
[0016]
If the temperature difference of the Vicat softening point of the thermoplastic resin constituting the heat-fusible film and the core material is 5 ° C. or more, preferably 10 ° C. or more, the above-mentioned problem in the molding process is completely eliminated, A desired molded sheet is obtained.
If the core material is a mixture of a plurality of thermoplastic resins, the highest Vicat softening point among them must be lower than the Vicat softening point of the thermoplastic resin constituting the heat-fusible film. It is.
Vicat softening point (JIS K 7206) is measured by placing a test piece with a thickness of 3 to 6.4 mm and an area of 10 x 10 mm or more on a Vicat softening point tester, applying a load with a needle from above the test piece, This is done by measuring the temperature when the needle is warmed and enters the specimen to a depth of 1 mm. At this time, the needle is a cylinder having a length of 3 mm and a cross section of 1 mm, the surface in contact with the test piece is flat, the applied load is 1000 to 1050 g, and the heating rate is 50 ± 5 ° C./hr.
[0017]
【Example】
According to the resin configurations shown in Table 1 (Examples, Nos. 1 to 8) and Table 2 (Comparative Examples, Nos. 9 to 11), core materials having the cross-sectional shapes shown in Tables 1 and 2 are formed by extrusion molding. Then, the core sheet and the covering material were bonded together to obtain the molded sheet shown in FIG. In Tables 1 and 2, PET represents polyethylene terephthalate, LDPE represents low density polyethylene, LLDPE represents linear low density polyethylene, PP represents polypropylene, and HDPE represents high density polyethylene. The thickness of the base material was 25 μm, and the thickness of the heat-fusible film was 25 μm.
Next, the obtained molded sheet was evaluated for (1) bundling property, (2) repeated bundling, (3) shape retention, and (4) bundling property by an automatic bundling machine by the following methods.
(1) Bundling property: The molded sheet was twisted three times by hand, and was bound in a double spiral state as shown in FIG. 4 (a). On the other hand, as shown in FIG.
(2) Repetitive bundling: 3 times twisting and untwisting of the molded sheet by hand is one cycle, and when the bundling is repeated after 3 cycles, the coating material and the core material are not peeled off and the core material is not damaged. The case where the coating material and the core material were peeled or the core material was damaged was regarded as a failure.
(3) Shape retention: When a molded sheet is twisted and bundled three times by hand, as shown in FIG. 4 (a), the one in which the twisted state is maintained for 5 minutes is accepted, and FIG. 4 (c) is accepted. As shown, the loosely bound state was rejected. In addition, as shown in FIG. 5, a molded sheet having a length of 100 mm is bent at a bending angle θ (bending angle θ ≧ 20 °) at a position 50 mm from the end, held for 1 second, and then held. And the bending angle θ ′ at the time of opening was measured. As a result, what held the state of (theta)-(theta) '<= 5 degree was set to pass, and the thing which is (theta)-(theta)'> 5 degree was made unacceptable.
(4) Bindability by automatic binding machine: A confectionery bag was bound using an automatic binding machine FT-40 (manufactured by Neurong Co., Ltd., product name), and those that could be bound were regarded as acceptable. In addition, the above-mentioned double helix state was set as the pass for the binding state.
[0018]
The results of the evaluation are shown in Table 3. As can be seen from Table 3, the molded sheet of the present invention is good in any evaluation of (1) binding property, (2) repeated binding, (3) shape retention, and (4) binding property by an automatic binding machine. Results were obtained.
[0019]
[Table 1]

[0020]
[Table 2]

[0021]
[Table 3]

[0022]
【The invention's effect】
According to the present invention, it is possible to obtain a molded sheet having a synthetic resin as a core material, which has excellent binding properties, repeated useability and shape retention, and can be stably bound by an automatic binding machine. Its industrial utility value is extremely high.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a cross-sectional explanatory view of a molded sheet of the present invention, wherein (a) to (c) show a case where there is one coating material, and (d) to (f) show a case where there are two coating materials.
FIG. 2 is a cross-sectional explanatory view of a covering material.
FIGS. 3A and 3B are cross-sectional explanatory views of a core material, and FIGS. 3A to 3H show various cross-sectional shapes of the core material.
FIG. 4 is an explanatory diagram of an evaluation method related to a binding state and shape retention.
FIG. 5 is an explanatory diagram of an evaluation method related to shape retention.
[Explanation of symbols]
DESCRIPTION OF

SYMBOLS

1, 3 ... Covering material 2 ... Core material 4 ... Base material 5 ... Heat-sealable film

Claims

Consists of a coating material in which a heat-sealable film made of a thermoplastic resin is laminated on the surface of a substrate and a core material made of a thermoplastic resin, and the core material is sandwiched integrally by the heat-sealable film of the coating material And a band-shaped twisted bundling cord coated so as to wrap, and the thermoplastic resin constituting the core material has a lower Vicat softening point than the thermoplastic resin constituting the heat-fusible film, A twisted and bound string, wherein the cross-sectional shape of the core material is oval, polygonal, curved, or indefinite, and the cross-sectional area of the core material is in the range of 0.10 to 1.00 cm ² .

The core material is covered with the heat-fusible film of the coating material so that the core material is sandwiched and wrapped together by bonding the core material to the surface of the heat-fusible film of the coating material. A twisted binding string, wherein the core material has an oval, polygonal, curved, or indeterminate cross section when the core material is heat-pressed and fused to the surface of the heat-fusible film. The twisted and bound string according to claim 1, which is shaped into a shape.

The core material is heat-pressed and bonded to the surface of the heat-fusible film of the coating material so that the core material is integrally sandwiched and wrapped with the heat-fusible film of the coating material. A twisted tie string, wherein the core material is previously shaped into an oval, polygonal, curved, or irregular cross-sectional shape, and at the time of thermocompression bonding, the oval, polygonal, curved, or irregular The twisted binding string according to claim 1, wherein the twisted tie string maintains a fixed cross-sectional shape.