Importance

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Abstract

An object is to prevent cracking of a radiant heat preventing film which occurs near an opening area. A heat insulated container 10 produced by coating an external surface of a glass internal container 12 with a radiant heat preventing film 24, disposing the internal container 12 inside an external container 16 with a gap 14 interposed therebetween, heating an opening area so as to melt the same to thereby unite the internal container 12 with the external container 16, and evacuating the gap 14 to a vacuum, is characterized in that a region 26 not coated with the radiant heat preventing film 24 is provided in the vicinity of the opening area of the external surface. As a result, cracking does not occur in the radiant heat preventing film 24 at the time of heating and melting the opening area 18. Accordingly, even if the vicinity of the opening area 18 is deformed at the time of uniting, there is no intrusion of the radiant heat preventing film 24 into the glass interior, no occurrence of cracking, and no occurrence of oozing of glass from the cracked portion leading to formation of protrusions. Therefore, breakage of the heat insulated container attributed to stress concentration in the vicinity of the opening area is radically reduced, and the fraction defective is lowered, thereby enabling a reduction in production cost. Furthermore, any whitening phenomenon is also prevented, thereby avoiding any deterioration of appearance.

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First Claim