Thermal insulation foamed sheet, thermal insulation foamed container and method for producing the same

Abstract

The present invention relates to a thermal insulation foamed sheet whose foaming height can be kept high by increasing a expansion ratio of foaming cells, thermal insulation foamed container using this and method for producing the same. In the thermal insulation foamed sheet according to the present invention, a foaming plane made of a foaming cell group is formed by heating the sheet in which a synthetic resin film is laminated on base paper and foaming the synthetic resin film using moisture contained in the base paper, and at least a part of the foaming plane is vacuum-suctioned so as to increase the foaming height of the foaming cell. Also, there can be made a thermal insulation foamed container having this foaming plane on at least its body section.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a thermal insulation foamed sheet, thermal insulation foamed container formed by vacuum-suctioning a foamed cell group foamed mainly using moisture in base paper and method for producing the same. BACKGROUND ART [0002] For insulating cups made from base paper as a base material, several structures provided with good touching feeling and insulation by foaming a laminate film laminated on the base material have been proposed. [0003] The JP-A-57-110439, for example, discloses such a structure that a water content contained in paper is vaporized by heating and this vaporized water content is used as a foaming material so as to foam a thermoplastic synthetic resin such as polyethylene film. [0004] With this method, however, the foaming height is limited, and there is a problem that, even if time for heating is prolonged, the foaming height can not be increased. [0005] On the other hand, in the JP-A-61-246041, a foam sheet and...

AI Technical Summary

Benefits of technology

[0022] For the thermal insulation foamed sheet according to the present invention, a sheet in which a synthetic resin film is laminated on base paper is heated, a foaming plane made of a foamed cell group is formed by foaming the synthetic resin film mainly using moisture contained in base paper, and the expansion ratio of the foaming cells is increased by vacuum-suctioning at least a part of the foaming plane so that the synthetic resin film can be foamed using the moisture contained in the base paper and the high expansion ratio can be maintained by vacuum-suctioning the foaming cells so as to prevent contraction of the foaming cells foamed at a high expansion ratio.

[0024] By this, the high expansion ratio can be maintained by preventing contraction of the foaming cells foamed at a high ratio.

[0025] Also, since the foaming plane is formed by heating and vacuum-suctioning, the heating temperature can be lowered and the heating time can be reduced. And moreover, deodorization of odors of ink, solvents, resin or lamination can be performed at the same time by vacuum-suctioning.

[0026] With the thermal insulation foamed container using the thermal insulation foamed sheet of the present invention, said thermal insulation foamed sheet is used at least on the body section of the container, and insulation efficiency is improved by high foaming height, and its feeling can be made better.

[0027] In the case of the thermal insulation foamed container having said foaming plane at least on the body section, a synthetic resin film is laminated on at least one side of base paper with the other side also subjected to lamination, and the body section or the container is heated so as to form a foaming plane made of a foamed cell group by foaming said synthetic resin film mainly using moisture contained in the base paper, and at least a part of the foaming plane is vacuum-suctioned so as to increase the foaming height of the foaming cell.

Problems solved by technology

With this method, however, the foaming height is limited, and there is a problem that, even if time for heating is prolonged, the foaming height can not be increased.

In this case, it is so constituted that the softened foam sheet is suctioned at a position other than the partial adhesion parts for expansion, which takes time and labor and causes the swollen portion to be largely expanded.

That constitution is not suitable for a cup, and it is difficult to form a foaming plane with good feeling.

When the moisture in the base paper is used in this way, the expansion ratio can be temporarily increased but there is a critical problem that the foaming cells shrink at cooling and the foaming height can not be maintained.

Then, water cooling and rapid cooling at −5 degrees centigrade were performed, but the foaming height can not be kept high.

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