Heat insulator

Abstract

A heat insulator is disclosed which simplifies processes of measures for preventing contamination of a surrounding caused by falling off of a silica aerogel in a silica-aerogel support heat insulator. In the silica-aerogel support heat insulator, a support layer whose melting point is lower than a melting point of a fiber supporting the silica aerogel is used, and by performing thermal-pressure bonding at a temperature lower than the melting point of the fiber but higher than the melting point of the support layer to cause the support layer to enter the fiber to combine the support layer and the fiber. Thus, processes of measures for preventing contamination of a surrounding caused by falling off of the silica aerogel can be simplified, and use in a large size and/or in a complicated shape is made possible.

Claims

1. A heat insulator, comprising: a fiber layer comprising a nonwoven fabric and silica aerogels, the nonwoven fabric being formed from fibers, the silica aerogels being supported by the nonwoven fabric and existing throughout the nonwoven fabric; at least one support layer comprising polyethylene having a melting point lower than a melting point of the fibers, and disposed on or above at least one surface of the fiber layer; and a combined layer resulting from the at least one support layer welded with the fiber layer, wherein a part of the polyethylene is integrated into the fiber layer and penetrates between the fibers of the nonwoven fabric, wherein the combined layer is not disposed on an entire area between the fiber layer and the at least one support layer, but is disposed in a partial area between the fiber layer and the at least one support layer.

2. The heat insulator according to claim 1, wherein the heat insulator has an exposed surface where the fiber layer is exposed from the at least one support layer at an end portion of the heat insulator in a planar direction.

3. The heat insulator according to claim 1, wherein the combined layer exists in a part of an interface between the fiber layer and the at least one support layer.

4. The heat insulator according to claim 2, wherein the combined layer exists in the exposed surface.

5. The heat insulator according to claim 4, wherein the combined layer exists in a part of an interface between the fiber layer and the at least one support layer, and wherein the combined layer extends from the exposed surface to a point at a constant length away from the exposed surface in a direction perpendicular to the exposed surface.

6. The heat insulator according to claim 5, wherein the constant length is a length not greater than a thickness of the heat insulator.

7. The heat insulator according to claim 4, wherein all or part of the combined layer faces the exposed surface.

8. The heat insulator according to claim 1, wherein the at least one support layer wraps the fiber layer and is stacked on or above one surface of the fiber layer, and wherein stacked portions of the at least one support layer are welded together to become a welded portion of the at least one support layer.

9. The heat insulator according to claim 1, wherein the combined layer exists in a planar manner.

10. A heat insulator, comprising: a fiber layer comprising a nonwoven fabric and silica aerogels, the nonwoven fabric being formed from fibers, the silica aerogels being supported by the nonwoven fabric and existing throughout the nonwoven fabric; at least one support layer comprising polyethylene having a melting point lower than a melting point of the fibers, and disposed on or above at least one surface of the fiber layer; and a combined layer resulting from the support layer welded with the fiber layer, wherein a part of the polyethylene is integrated into the fiber layer and penetrates between the fibers of the nonwoven fabric, wherein the support layer wraps the fiber layer and includes a weld portion where end portions of the support layer are welded together, wherein the welded portion exists in a planar manner, wherein the combined layer is not disposed on an entire area between the fiber layer and the at least one support layer, but is disposed in a partial area between the fiber layer and the at least one support layer, and wherein the partial area exists at an end portion of the heat insulator.

11. The heat insulator according to claim 4, wherein the combined layer exists in a part of an interface between the fiber layer and the at least one support layer, wherein the combined layer has (1) a length extending from a first end of the exposed surface to a second end of the exposed surface, and (2) a width extending in a direction perpendicular to the exposed surface, and wherein the width of the combined layer is (1) same from the first end of the exposed surface to the second end of the exposed surface, and (2) less than a thickness of the heat insulator.

12. A heat insulator, comprising: a fiber layer comprising a nonwoven fabric and silica aerogels, the nonwoven fabric being formed from fibers, the silica aerogels being supported by the nonwoven fabric and existing throughout the nonwoven fabric; at least one support layer comprising polyethylene having a melting point lower than a melting point of the fibers, and disposed on or above at least one surface of the fiber layer; a first combined layer resulting from the at least one support layer welded with the fiber layer, wherein a first part of the polyethylene is integrated into the fiber layer and penetrates between the fibers of the nonwoven fabric, and wherein the first combined layer is disposed in a first partial area between the fiber layer and the at least one support layer; and a second combined layer resulting from the at least one support layer welded with fiber layer, wherein a second part of the polyethylene is integrated into the fiber layer and penetrates between the fibers of the nonwoven fabric, and wherein the second combined layer is disposed in a second partial area between the fiber layer and the at least one support layer, wherein the first combined layer is not disposed on an entire area between the fiber layer and the at least one support layer, but is disposed in the first partial area between the fiber layer and the at least one support layer, and wherein the second combined layer is not disposed on an entire area between the fiber layer and the at least one support layer, but is disposed in the second partial area between the fiber layer and the at least one support layer.

13. The heat insulator according to claim 12, wherein the first partial area is disposed at one end of the heat insulator and the second partial area is disposed at another end of the heat insulator.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1A is a sectional view of a side surface of a heat insulator in Embodiment 1 of the present invention;

(2) FIG. 1B is an enlarged view of a welded part of the heat insulator in Embodiment 1 of the present invention;

(3) FIG. 2A is a perspective view of the heat insulator after thermal welding of a nonwoven fabric and a support layer in Embodiment 1 of the present invention;

(4) FIG. 2B is a schematic view of a cut shape after the thermal welding of the nonwoven fabric and the support layer in Embodiment 1 of the present invention;

(5) FIG. 2C is a schematic view of a cut shape after the thermal welding of the nonwoven fabric and the support layer in Embodiment 1 of the present invention;

(6) FIG. 3A is a perspective view of a heat insulator in Embodiment 2 of the present invention;

(7) FIG. 3B is a diagram of the heat insulator as viewed from a direction of arrow A of FIG. 3A;

(8) FIG. 3C is a sectional view taken along line B-B of FIG. 3B;

(9) FIG. 3D is a sectional view after cutting of the heat insulator in Embodiment 2 of the present invention;

(10) FIG. 4A is a perspective view of a heat insulator in Embodiment 3 of the present invention;

(11) FIG. 4B is a diagram of the heat insulator as viewed from a direction of arrow C of FIG. 4A;

(12) FIG. 4C is a sectional view taken along line D-D of FIG. 4B;

(13) FIG. 4D is a sectional view after cutting of the heat insulator in Embodiment 2 of the present invention;

(14) FIG. 5 is a schematic view of a partially enlarged silica aerogel; and

(15) FIG. 6 is a sectional view of a side surface of a traditional heat insulator.

DESCRIPTION OF EMBODIMENTS

(16) Hereinafter, a description will be given of each embodiment of the present invention with reference to the accompanying drawings. Note that, the present invention is not limited by the following embodiments.

Embodiment 1

(17) Embodiment 1 of the present invention will be described using FIGS. 1A and 1B and FIGS. 2A, 2B, and 2C.

(18) FIG. 1A is a sectional view of a side surface of heat insulator 101 in Embodiment 1. As illustrated in FIG. 1A, in heat insulator 101, one surface of silica-aerogel support fiber 102 is covered by support layer 103a, and a rear surface of silica-aerogel support fiber 102 is covered by support layer 103b.

(19) Silica-aerogel support fiber 102 (exemplary fiber layer) is a nonwoven fabric in which silica aerogels are supported. The silica aerogels are supported over the entire surface and in the whole thickness direction of silica-aerogel support fiber 102.

(20) FIG. 1B is an enlarged view of a welded part of the heat insulator in Embodiment 1. As illustrated in FIG. 1B, a part of support layer 103a is integrated into silica-aerogel support fiber 102 between support layer 103a and silica-aerogel support fiber 102. Thus, combined layer 104 of support layer 103a and silica-aerogel support fiber 102 is Ruined. Note that, a similar combined layer is formed also between support layer 103b and silica-aerogel support fiber 102.

(21) In Embodiment 1, the thickness of silica-aerogel support fiber 102 is 1 mm, the thicknesses of support layers 103a and 103b are 60 ?m, and the thickness of combined layer 104 is 20 ?m, for example. Moreover, the thickness of a combined layer (not illustrated) of support layer 103b and silica-aerogel support fiber 102 is also 20 ?m.

(22) Support layers 103a and 103b herein are formed from a material (substance) whose melting point is lower than a fabric forming silica-aerogel support fiber 102. As a material forming support layers 103a and 103b, polyethylene (melting point of 115 to 135? C.) can be used, for example. As a fiber forming silica-aerogel support fiber 102, polyester (melting point of 255 to 260? C.) can be used, for example. Note that, as to selecting of a material forming support layers 103a and 103b and silica-aerogel support fiber 102, the material is not limited to those mentioned above, and a variety of materials can be selected.

(23) In Embodiment 1, a description will be given, as an example, of a case where support layers 103a and 103b are composed of a polyethylene sheet and the thickness of the polyethylene sheet is 60 ?m, but the thickness is not limited to this value. When the thickness of the polyethylene sheet is equal to or greater than 40 ?m, combined layer 104 illustrated in FIG. 1B can be formed. Note that, when the thickness of the polyethylene sheet is less than 40 ?m, since support layers 103a and 103b penetrate into silica-aerogel support fiber 102 as mentioned above, the thickness of support layers 103a and 103b may become small, and a hole may be generated in the surface of heat insulator 101.

(24) Meanwhile, when the thickness of support layers 103a and 103b is too large, the flexibility as heat insulator 101 may decrease, and/or the proportion of the thickness of support layers 103a and 103b in the thickness of the entirety of heat insulator 101 may become large, and this may cause higher thermal conductivity as heat insulator 101. For these reasons, the thickness of support layers 103a and 103b is preferably equal to or less than 100 ?m.

(25) As a shape of the entirety of heat insulator 101, the shape illustrated in FIG. 2A can be cited as an example. FIG. 2A illustrates heat insulator 101 in which support layers 103a and 103b and silica-aerogel support fiber 102 are combined and of which an upper surface and lower surface have a rectangular shape (in other words, the entire shape is a rectangular solid).

(26) In heat insulator 101 illustrated in FIG. 2A, support layers 103a and 103b and silica-aerogel support fiber 102 are combined by a combined layer (not illustrated) and they are combined in a homogeneous manner. For this reason, even when heat insulator 101 is cut in any direction on the plane of heat insulator 101, the state where support layers 103a and 103b and silica-aerogel support fiber 102 have been combined is maintained. The planar portion of silica-aerogel support fiber 102 has a structure covered by support layers 103a and 103b. Moreover, since no welding is applied between support layers 103a and 103b, end surfaces resulting from the cut are in a state where silica-aerogel support fiber 102 (and silica aerogel) is exposed.

(27) FIG. 2B and FIG. 2C are each a schematic diagram illustrating a cut shape in a case where heat insulator 101 is cut after the thermal welding of support layers 103a and 103b and silica-aerogel support fiber 102.

(28) FIG. 2B illustrates a state where one heat insulator 101 (see, e.g., FIG. 1A), which is a rectangular solid, is cut and thus divided into two heat insulators 201a and 201b of the same rectangular solid. Heat insulators 201a and 201b are usable as a heat insulator without any change, as in the case of heat insulator 101 before cutting.

(29) FIG. 2C illustrates a state where one heat insulator 101 (e.g., see FIG. 1A), which is a rectangular solid, is cut and thus divided into two heat insulators 201c and 201d having the same triangular prism. Heat insulators 201a and 201b are usable as a heat insulator without any change, as in the case of heat insulator 101 before cutting.

(30) As a cutting means, it is possible to use edged tools, such as a cutter, and a press configuration, such as Thompson type. More specifically, since a cutting means not requiring heating can be used, heat insulator 101 can be easily cut into any shape.

(31) <Formation Method of Combined Layer 104>

(32) A formation method of combined layer 104 illustrated in FIG. 1B will be described, herein.

(33) Combined layer 104 is formed by pressurization while heating at a temperature which is higher than a melting point of support layer 103a but lower than a melting point of a fiber forming silica-aerogel support fiber 102.

(34) For example, pressure is applied between two heated rollers and a laminated body in which silica-aerogel support fiber 102 is held between support layers 103a and 103b is caused to pass through between the two rollers. As described above, in Embodiment 1, polyethylene (melting point of 115 to 135? C.) is used as a material for support layers 103a and 103b, and polyester (melting point of 255 to 260? C.) is used as a fiber of silica-aerogel support fiber 102. Therefore, combined layer 104 can be formed by causing the laminated body to pass through between the rollers five times to perform heating and pressurization, while setting the heating temperature to 150? C., the pressurization pressure to 40 MPa, and the speed to 50 mm/s.

(35) The thickness of combined layer 104 is adjustable by the heating temperature and pressurization pressure. The thickness of combined layer 104 becomes larger as the heating temperature and pressurization pressure become higher, and the thickness of combined layer 104 becomes smaller as the heating temperature and pressurization pressure become lower.

(36) The combination strength of support layers 103a and 103b and silica-aerogel support fiber 102 becomes higher as the thickness of combined layer 104 becomes larger. However, the amount of penetration of support layers 103a and 103b into silica-aerogel support fiber 102 (thickness of combined layer 104) increases, so that the thermal conductivity as heat insulator 101 becomes high.

(37) Meanwhile, the combination strength of support layers 103a and 103b and silica-aerogel support fiber 102 becomes lower, as the thickness of combined layer 104 becomes smaller. However, since the amount of penetration of support layers 103a and 103b into silica-aerogel support fiber 102 (thickness of combined layer 104) decreases, the thickness of the materials of support layers 103a and 103b can be reduced. Thus, the thickness of heat insulator 101 as a whole can be reduced.

(38) In Embodiment 1, combined layer 104 is formed by the conditions and method mentioned above. As a result, the combination strength of support layer 103a and silica-aerogel support fiber 102 in heat insulator 101 indicates that the load for separation in a right angle direction with 300 mm/min in heat insulator 101 having a width of 15 mm becomes equal to or greater than 3N. Further, the increase of thermal conductivity is suppressed to be less than 10%.

(39) Note that, the heating conditions and pressurizing conditions described above are only exemplary, and it is possible to form combined layer 104 in the same manner as described above even when other conditions are selected. However, change may be needed depending on a material to be used. Furthermore, although a description has been given with an example in which two heated rollers are used as a means for heating and pressurizing in Embodiment 1, the means for heating and pressurizing is not limited to the means described above, and another means, such as heating and pressurizing using an impulse sealer, may be used.

Effects of Embodiment 1

(40) As has been described above, according to heat insulator 101 of Embodiment 1, in a use environment where no impact is caused by falling off of a silica aerogel from a fiber side surface, a heat insulator can be created in a larger size, and the heat insulator can be cut into a required shape after being created in a larger size. Therefore, it is made possible to use heat insulator 101 in a larger size or a complicated shape in electronic devices, precision equipment, cold equipment, and/or the like, for example.

(41) As mentioned above, although it is necessary to take measures for preventing contamination of a surrounding caused by falling off of a silica aerogel, processing of the measures can be simplified with heat insulator 101 of Embodiment 1.

Embodiment 2

(42) Embodiment 2 of the present invention will be described using FIG. 3A, FIG. 3B, FIG. 3C, and FIG. 3D. Note that, a configuration that is different from that of Embodiment 1 will be mainly described in the description of Embodiment 2, hereinafter. In FIGS. 3A to 3D, the same reference numerals are given to the same components as Embodiment 1, and their descriptions are omitted.

(43) FIG. 3A is a perspective view of heat insulator 101 in Embodiment 2. As illustrated in FIG. 3A, support layer 301 wraps silica-aerogel support fiber 102. A surface of heat insulator 101 as viewed from the direction of arrow A illustrated in FIG. 3A is an example of the exposed surface where silica-aerogel support fiber 102 and the silica aerogel are exposed.

(44) FIG. 3B is a diagram of heat insulator 101 of FIG. 3A as viewed from the direction of arrow A. As illustrated in FIG. 3B, support layer 301 is thermally welded at support layer welding part 301a corresponding to one side surface of silica-aerogel support fiber 102 to seal the side surface of silica-aerogel support fiber 102. Support layer welding part 301a is a portion where two support layers are welded together (i.e., a portion where the end portions of the support layers are welded together).

(45) FIG. 3C is a sectional view taken along line B-B of FIG. 3B. As illustrated in FIG. 3C, heat insulator 101 includes combined layer 302 of support layer 301 and silica-aerogel support fiber 102. Combined layer 302 herein is not disposed on the entire surface of heat insulator 101 (silica-aerogel support fiber 102), but is disposed in a depth direction in FIG. 3C. In other words, combined layer 302 is disposed in the full length (range indicated by both arrows a in FIG. 3B) of silica-aerogel support fiber 102. As a result, heat insulator 101 is protected in periphery by support layer welding part 301a and combined layer 302 and is thus structurally hard. The width (the length of the horizontal direction in the drawing) of combined layer 302 illustrated in FIG. 3C is 10 mm, for example.

(46) As illustrated in FIG. 3C, combined layer 302 exists in a part of an interface between silica-aerogel support fiber 102 and support layer 301.

(47) Heat insulator 101 is cut into an optional shape after formation of combined layer 302. FIG. 3D is a sectional view after cutting of heat insulator 101 illustrated in FIGS. 3A to 3C (after cutting along the width direction of heat insulator 101). As illustrated in FIG. 3D, heat insulator 101 is cut at a part where combined layer 302 of support layer 301 and silica-aerogel support fiber 102 exists. Heat insulator 101 herein is cut at the center of the width of combined layer 302 as an example. As a result, combined layer 302 after cutting has a width of 5 mm. As described herein, by cutting at a part where combined layer 302 exists, the combination of support layer 301 and silica-aerogel support fiber 102 is maintained. Thus, heat insulator 101 after cutting becomes usable as a heat insulator covered by support layer 301 as in the case of heat insulator 101 before cutting.

(48) Furthermore, as illustrated in FIG. 3D, combined layer 302 exists in the exposed surface In addition, as illustrated in FIG. 3D, combined layer 302 is present from the exposed surface to have a constant length toward the inside of heat insulator 101 (i.e., along the longitudinal direction of heat insulator 101 from the exposed surface). The constant length is a length not greater than a thickness of heat insulator 101. Further, as illustrated in FIG. 3D, all or part of combined layer 302 faces the exposed surface.

(49) Support layer 301 herein uses a material whose melting point is lower than a melting point of the fiber forming silica-aerogel support fiber 102. In Embodiment 2, for example, polyethylene (melting point of 115 to 135? C.) can be used as a material forming support layer 301. Moreover, as a fiber forming silica-aerogel support fiber 102, polyester (melting point of 255 to 260? C.) can be used. Note that, as to the selecting of a material forming support layer 301 and silica-aerogel support fiber 102, the material is not limited to the above and a variety of materials are selectable.

(50) <Formation Method of Combined Layer 302>

(51) A description will be herein given of a formation method of combined layer 302 illustrated in FIG. 3C.

(52) Combined layer 302 is formed by pressurization while heating at a temperature which is higher than a melting point of support layer 103a but lower than a melting point of a fiber forming silica-aerogel support fiber 102.

(53) Support layer 301 and silica-aerogel support fiber 102 are subjected to heating under pressurization, using an impulse sealer, for example. As described above, in Embodiment 2, polyethylene (melting point of 115 to 135? C.) is used as a material which forms support layer 301, and polyester (melting point of 255 to 260? C.) is used as a fiber which forms silica-aerogel support fiber 102. Thus, pressurization and heating are performed to form combined layer 302 while the heating temperature is set to 180? C. and the pressurization pressure is set to 20 MPa.

(54) The heating conditions and pressurization conditions described above are only exemplary, and even when another condition is selected, it is possible to form combined layer 302 as described above. However, change may be needed depending on a material to be used. Moreover, although a description has been given, as an example, of the case where an impulse sealer is used as the means for heating and pressurizing in Embodiment 2, the means for heating and pressurizing is not limited to this case, and another means may be used.

Effects of Embodiment 2

(55) As described above, according to heat insulator 101 of Embodiment 2, the effects of Embodiment 1 mentioned above can be obtained. Further, according to heat insulator 101 of Embodiment 2, formation of combined layer 302 does not have to be performed on the entire surface of heat insulator 101, and the configuration of pressurization equipment can be simplified.

Embodiment 3

(56) Embodiment 3 of the present invention will be described using FIG. 4A, FIG. 4B, FIG. 4C, and FIG. 4D. Note that, a description will be mainly given of a configuration that is different from that of Embodiment 2, in the description of Embodiment 3. In FIGS. 4A to 4D, the same reference numerals are given to the same components as Embodiment 2, and their descriptions are omitted.

(57) FIG. 4A is a perspective view of heat insulator 101 in Embodiment 3. As illustrated in FIG. 4A, support layer 401 wraps silica-aerogel support fiber 102. The surface of heat insulator 101 as viewed from the direction of arrow C illustrated in FIG. 4A is an exemplary exposed surface where silica-aerogel support fiber 102 and the silica aerogel are exposed.

(58) FIG. 4B is a diagram of heat insulator 101 of FIG. 4A as viewed from the direction of arrow C. As illustrated in FIG. 4B, support layer 401a and support layer 401b in support layer 401 are stacked on an upper surface of silica-aerogel support fiber 102. Support layer 401a and support layer 401b are welded together, and seal two side surfaces of silica-aerogel support fiber 102. As described herein, in Embodiment 3, the welded part in support layer 401 becomes a flat surface, and is located on the upper surface side or lower surface side of heat insulator 101. Note that, support layer 401a and support layer 401b may also be called a welded part.

(59) FIG. 4C is a sectional view taken along line D-D of FIG. 4B. As illustrated in FIG. 4C, heat insulator 101 includes combined layer 302 of support layer 401 and silica-aerogel support fiber 102. Combined layer 302 herein is not disposed on the entire surface of heat insulator 101 (silica-aerogel support fiber 102), but is disposed in a depth direction in FIG. 4C. In other words, combined layer 302 is disposed in the full length of a width direction of silica-aerogel support fiber 102 (range indicated by both arrows b illustrated in FIG. 4B). The width (the length of the horizontal direction in the drawing) of combined layer 302 illustrated in FIG. 4C is 10 mm, for example.

(60) As illustrated in FIG. 4C, combined layer 302 exists in a part of an interface between silica-aerogel support fiber 102 and support layer 401 (support layer 401b).

(61) FIG. 4D is a sectional view after cutting of heat insulator 101 illustrated in FIG. 4A to FIG. 4C (after cutting along the width direction of heat insulator 101). As illustrated in FIG. 4D, heat insulator 101 is cut at a part where combined layer 302 of support layer 401 and silica-aerogel support fiber 102 exists. Heat insulator 101 herein is cut at the center of the width of combined layer 302 as an example. As a result, combined layer 302 after cutting has a width of 5 mm. As described herein, by cutting at a part where combined layer 302 exists, the combination of support layer 401 and silica-aerogel support fiber 102 is maintained. Thus, heat insulator 101 after cutting becomes usable as a heat insulator covered by support layer 401 as in the case of heat insulator 101 before cutting.

(62) Furthermore, as illustrated in FIG. 4D, combined layer 302 exists in the exposed surface In addition, as illustrated in FIG. 4D, combined layer 302 is present from the exposed surface to have a constant length toward the inside of heat insulator 101 (i.e., along the longitudinal direction of heat insulator 101 from the exposed surface). The constant length is a length not greater than a thickness of heat insulator 101. Further, as illustrated in FIG. 4D, all or part of combined layer 302 faces the exposed surface.

Effects of Embodiment 3

(63) As described above, according to heat insulator 101 of Embodiment 3, the effects of Embodiment 1 mentioned above can be obtained. More particularly, use in a long shape in electronic devices, precision instruments, or cold devices is made possible, for example.

(64) <Summary of the Disclosure>

(65) A heat insulator of the present disclosure includes: a fiber layer in which a silica aerogel is supported; and at least one support layer disposed on at least one surface of the fiber layer, in which the heat insulator further comprises a combined layer resulting from the at least one support layer combined with the fiber layer by entering of the at least one support layer into the fiber layer.

(66) In the heat insulator of the present disclosure, a melting point of the at least one support layer may be lower than a melting point of the fiber layer.

(67) In the heat insulator of the present disclosure, an exposed surface where the fiber layer and the silica aerogel are exposed exists in at least one surface in an end portion of the heat insulator in a planar direction.

(68) In the heat insulator of the present disclosure, the combined layer exists in a part of an interface between the fiber layer and the at least one support layer.

(69) In the heat insulator of the present disclosure, the combined layer exists in the exposed surface.

(70) In the heat insulator of the present disclosure, the combined layer exists with a constant length extending from the exposed surface toward an inside of the heat insulator.

(71) In the heat insulator of the present disclosure, the constant length is a length not greater than a thickness of the heat insulator.

(72) In the heat insulator of the present disclosure, all or part of the combined layer faces the exposed surface.

(73) In the heat insulator of the present disclosure, the at least one support layer includes a plurality of the supported layers, one of which wraps the fiber layer and which includes a welded portion where end portions of the one of the plurality of support layers are welded together.

(74) In the heat insulator of the present disclosure, the one of the plurality of support layers wraps the fiber layer and is stacked on one surface of the fiber layer, and includes a welded portion where the stacked support layers are welded together.

(75) In the heat insulator of the present disclosure, the welded layer and the combined layer exist around the heat insulator.

INDUSTRIAL APPLICABILITY

(76) A heat insulator of the present invention can simplify processes of measures for preventing contamination of a surrounding caused by falling off of a silica aerogel and can increase in size and is usable in a complicated shape. The heat insulator of the present invention is applicable not only to heat insulation of electronic devices, such as mobile devices, but also to heat insulation of large devices, such as cold devices.

REFERENCE SIGNS LIST

(77) 101, 601 Heat insulator 102, Silica-aerogel support fiber 103a, 103b, 301, 401, 401a, 401b, 604a, 604b Support layer 104, 302 Combined layer 201a, 201b, 201c, 201d Heat insulator after cutting 301a Support layer welding part 501 Silica primary particle 502 Silica secondary particle 503 Void 602 Silica aerogel 603 Nonwoven fabric 605 Graphite sheet