Vacuum Heat Insulating Material, Method of Producing Vacuum Heat Insulating Material, and Heat Insulating Box Body Using Vacuum Heat Insulating Material
Disclosed is a vacuum heat insulating material. Also disclosed is a heat insulating box using the vacuum heat insulating material. The vacuum heat insulating material includes a core member and envelope members having gas-barrier properties and including heat-seal layers. The envelope members are opposed to each other in such a manner that the core member is disposed between the heat-seal layers. The envelope members are entirely heated to a temperature at which the heat-seal layers are melted, and the heat-seal layers are heat sealed to each other by applying uniform pressure to the entire envelope members from outside to inside the envelope members.
1 . A vacuum heat insulating material comprising:
a core member; and
envelope members having gas-barrier properties and including heat-seal layers, the envelope members being opposed to each other in such a manner that the core member is disposed between the heat-seal layers, wherein
the envelope members are entirely heated to a temperature at which the heat-seal layers are melted, and
the heat-seal layers are heat sealed to each other by applying uniform pressure from outside to inside the envelope members to a first portion of the envelope members that at least faces the core member, and to a second portion of the envelope members that is in a vicinity of the core member.
2 . The vacuum heat insulating material of claim 1 , wherein
the core member is sealed under reduced pressure between the envelope members.
3 . The vacuum heat insulating material of claim 1 , wherein
a third portion of the envelope members are previously heat-seated after an inside of the envelope members is reduced in pressure, the third portion being outside the second portion.
4 . The vacuum heat insulating material of claim 1 , wherein
the pressure is applied by a fluid.
5 . The vacuum heat insulating material of claim 4 , wherein
the pressure is applied by the fluid directly to the envelope members.
6 . The vacuum heat insulating material of claim 4 , wherein
the fluid is a gas.
7 . The vacuum heat insulating material of claim 6 , wherein
the pressure is atmospheric pressure.
8 . The vacuum heat insulating material of claim 1 , wherein
the heat-seal layers are made of polyethylene.
9 . The vacuum heat insulating material of claim 1 , wherein
each of the envelope members have a protective layer made of polyethylene terephthalate as an outermost layer thereof.
10 . A method of producing a vacuum heat insulating material, the method comprising:
covering a core member with envelope members, each of the envelope members having a gas barrier layer and a heat-seal layer,
evacuating an inside of the envelope members and heat sealing peripheries of the envelope members; and
heat-sealing a portion by uniformly applying heat sufficient to melt the heat-seal layer to a portion where the envelope members are in contact with each other, the portion being inside the heat-sealed peripheries.
11 . The method of producing a vacuum heat insulating material of claim 10 , wherein
the heat is applied out of contact with the portion.
12 . The method of producing a vacuum heat insulating material of claim 10 , wherein
the heat is applied by radiant heat from a heater.
13 . A method of producing a vacuum heat insulating material, the method comprising:
covering a core member with envelope members in a reduced pressure space, each of the envelope members having a gas barrier layer and a heat-seal layer;
maintaining the reduced pressure space at a temperature higher than a melting point of the heat-seal layers so as to bring the heat-seal layers to a predetermined molten state;
returning the reduced pressure space to normal pressure, while pressing the peripheries of the envelope members; and
heat-sealing the envelope members including a non-pressed portion of the envelope members by contacting the envelope members with each other.
14 . A vacuum heat insulating material according to claim 1 , said vacuum heat insulating material included in a heat insulating box which further comprises:
an outer box;
an inner box; and
a foam insulation material filled in a space formed between the outer box and the inner box;
said vacuum heat insulating material provided between the outer box and the inner box, the vacuum heat insulating material being at least partly buried in the foam insulation material.
15 . A method of producing a vacuum heat insulating material according to claim 1 , said vacuum heat insulating material included in a heat insulating box which further comprises:
an outer box;
an inner box; and
a foam insulation material filled in a space formed by the outer box and the inner box;
a vacuum heat insulating material provided between the outer box and the inner box, the vacuum heat insulating material being at least partly buried in the foam insulation material.