Toyo Seikan Kaisha, Ltd.

Senji Ito

Kenji Suzuki

Tadahiko Katsura

Kikuo Matsuoka

Kazumi Hirota

Yotaro Tsutsumi

Ichiro Hori

Disclosed is an easily openable heat seal lid for sealing a vessel proper by forming a heat-sealed portion between the lid and the vessel proper, which comprises a laminate comprising at least an inner face member composed of a thermoplastic resin and a metal foil, wherein scores defining a portion to be opened are formed on the side inner than the portion to be heat-sealed so that the scores extend to the midway of the thickness direction of the metal foil, and said inner face member comprises at least one heat-sealable thermoplastic resin layer having an adhesion strength of at least 800 g/15 mm to the metal foil, a tear strength lower than 3.0 kg and a tensile modulus of at least 300 kg/cm.sup.2. In this heat seal lid, the resin layer can be broken sharply along the scores and opening can be accomplished very easily.

Easily-openable heat seal lid

Disclosed is a retort-sterilizable laminated structure comprising an aluminum foil or sheet, a heat-sealable crystalline propylene type resin layer formed on one surface of the aluminum foil or sheet and a heat-resistant resin layer formed on the other surface of the aluminum foil or sheet, wherein the aluminum foil or sheet is heat-fusion-bonded to said crystalline propylene type resin layer through a layer of a modified olefin resin having a degree of crystallization of 15 to 95% and a carbonyl group concentration of 1 to 600 meq/100 g of the polymer, in which the majority of the structural olefin units are propylene units and the minority of the structural olefin units are ethylene units. As the modified olefin polymer, a modified ethylene-propylene copolymer or a blend of a modified propylene type polymer with an ethylene type polymer is preferably employed.

Retort-sterilizable laminated structure and process for preparation

A packaging material for food to be subjected to high-temperature short-time sterilization, which comprises a flexible laminate sheet including (a) a heat-sealable inner face layer of a crystalline polypropylene, (b) an outer face layer of a thermoplastic or thermosetting resin having a melting point or decomposition point higher than the melting point of said polypropylene and, if desired, (c) an oxygen-barrier layer interposed between said layers (a) and (b), said polypropylene layer being composed of a film of a polypropylene having a melt flow index of 0.5 to 3, said film being characterized in that (i) when the film is extracted in salad oil at 130.degree. C. for 30 minutes, the amount extracted of the polypropylene is smaller than 1500 ppm, (ii) the polypropylene film has a pseudohexagonal crystal form or a crystal form of a combination of the pseudohexagonal system and .alpha.-monoclinic system and a degree of orientation not higher than 3.0 and (iii) the surface of the polypropylene film confronting the layer (b) has a tension in the wet state (wetting tension T.sub.1) of at least 38 dyne/cm when it is allowed to stand still in an atmosphere of a temperature of 20.degree. C. and a relative humidity of 40% for 1 week.

Growing community of inventors

Ayase, Japan

Senji Ito