JP2016037973A - Vacuum heat insulation material - Google Patents

Vacuum heat insulation material Download PDF

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JP2016037973A
JP2016037973A JP2014159483A JP2014159483A JP2016037973A JP 2016037973 A JP2016037973 A JP 2016037973A JP 2014159483 A JP2014159483 A JP 2014159483A JP 2014159483 A JP2014159483 A JP 2014159483A JP 2016037973 A JP2016037973 A JP 2016037973A
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core material
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vacuum heat
heat insulating
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杉尾　圭太郎
Keitaro Sugio
圭太郎 杉尾
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Achilles Corp
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Abstract

PROBLEM TO BE SOLVED: To provide a vacuum heat insulation material excellent in a heat insulation property and capable of retaining strength.SOLUTION: A vacuum heat insulation material 1 comprises a core material 2 and a cover material 3 covering the core material 2, and is sealed by evacuating the inside of the cover material 3. The core material 2 is constituted by laminating a plurality of core material layers 23, in which an inorganic powder 21 and inorganic fibers 22 are mixed and compression-molded, and the percentage content of the inorganic fibers 22 of one face side 23a of the thickness direction is made smaller than the percentage content of the other face side 23b of the thickness direction.SELECTED DRAWING: Figure 1

Description

本発明は真空断熱材に関する。   The present invention relates to a vacuum heat insulating material.

冷蔵庫、建築材料、電子機器や事務機器などで高い断熱性能が要求される場合の断熱材として真空断熱材が用いられている。例えば、特許文献１に開示された真空断熱材では、シリカ粉体と無機繊維を混合して均一に分散させ、加圧成形して芯材とし、芯材を外被材で覆って、外被材の内部を減圧密封するようにしている。   Vacuum heat insulating materials are used as heat insulating materials when high heat insulating performance is required in refrigerators, building materials, electronic devices, office equipment, and the like. For example, in the vacuum heat insulating material disclosed in Patent Document 1, silica powder and inorganic fibers are mixed and uniformly dispersed, pressure-molded to form a core material, the core material is covered with a jacket material, The inside of the material is sealed under reduced pressure.

特開２００８−２１５５３８号公報JP 2008-215538 A

ところが、特許文献１の真空断熱材では、無機繊維がシリカ粉体に均一に分散されていることから、表面の無機繊維が熱橋となり十分な断熱性能が得られないという問題がある。
一方、無機繊維の混合は、芯材の強度を確保するために必要である。 However, in the vacuum heat insulating material of Patent Document 1, since inorganic fibers are uniformly dispersed in the silica powder, there is a problem that the surface inorganic fibers become a thermal bridge and sufficient heat insulating performance cannot be obtained.
On the other hand, mixing of inorganic fibers is necessary to ensure the strength of the core material.

本発明は、かかる従来技術に鑑みてなされたものであり、断熱性能に優れ、強度も確保できる真空断熱材を提供することを目的とするものである。   This invention is made | formed in view of this prior art, and it aims at providing the vacuum heat insulating material which is excellent in heat insulation performance and can ensure intensity | strength.

上記目的を達成するため、本発明にかかる真空断熱材は、
芯材と、前記芯材を覆う外被材とを有し、前記外被材の内部を減圧密封した真空断熱材であって、
前記芯材は、無機粉末と無機繊維とを混合して圧縮成形した複数の芯材層を積層して構成し、
前記各芯材層は、厚さ方向の一方面側の前記無機繊維の含有率が厚さ方向他方面側より小さく構成される、
ことを特徴とする。 In order to achieve the above object, the vacuum heat insulating material according to the present invention is:
A vacuum insulating material having a core material and a jacket material covering the core material, wherein the inside of the jacket material is sealed under reduced pressure,
The core material is constituted by laminating a plurality of core material layers obtained by mixing and compressing inorganic powder and inorganic fibers,
Each core layer is configured such that the content of the inorganic fiber on one side in the thickness direction is smaller than that on the other side in the thickness direction.
It is characterized by that.

本発明によれば、断熱性能に優れ、強度も確保できる真空断熱材とすることができる。   According to this invention, it can be set as the vacuum heat insulating material which is excellent in heat insulation performance and can ensure intensity | strength.

本発明の真空断熱材の一実施の形態にかかる横断面図である。It is a cross-sectional view concerning one embodiment of the vacuum heat insulating material of the present invention. 本発明の真空断熱材の一実施の形態にかかる芯材層の部分拡大断面図である。It is a partial expanded sectional view of the core material layer concerning one embodiment of the vacuum heat insulating material of the present invention. 本発明の真空断熱材の他の一実施の形態にかかる横断面図である。It is a cross-sectional view concerning other one Embodiment of the vacuum heat insulating material of this invention. 本発明の真空断熱材のさらに他の一実施の形態にかかる横断面図である。It is a cross-sectional view concerning another one Embodiment of the vacuum heat insulating material of this invention. 本発明の真空断熱材の一実施の形態にかかる繊維含有率と密度の関係を示すグラフである。It is a graph which shows the relationship between the fiber content rate and density concerning one Embodiment of the vacuum heat insulating material of this invention.

以下、本発明を実施するための形態について、図面を参照して詳細を説明する。
本発明における真空断熱材１は、芯材２と、芯材２を覆う外被材３とを有し、外被材３の内部を減圧密封して構成されている。
芯材２は、無機粉末２１と無機繊維２２とを混合して圧縮成形した複数、例えば２層の芯材層２３，２３を積層して構成されている。なお、芯材層２３は、２層に限らず、３層や４層などであっても良く（図３，図４参照）、さらに多層であっても良い。
真空断熱材１は、無機粉末２１と無機繊維２２とを混合してプレスなどで圧縮成形して、例えば、２層の芯材層２３，２３を積層した芯材２を成形した後に、これまでと同様の工程で、ガスバリヤ性に優れた外袋となる外被材３に挿入し、乾燥の工程を経て、内部を減圧しながら外被材３の開口部をシールすることで、減圧密封される。 DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.
The vacuum heat insulating material 1 in the present invention includes a core material 2 and a jacket material 3 that covers the core material 2, and is configured by sealing the inside of the jacket material 3 under reduced pressure.
The core material 2 is configured by laminating a plurality of, for example, two core material layers 23 and 23 obtained by mixing and compressing the inorganic powder 21 and the inorganic fibers 22. The core material layer 23 is not limited to two layers, but may be three layers, four layers, or the like (see FIGS. 3 and 4), or may be a multilayer.
The vacuum heat insulating material 1 is obtained by mixing the inorganic powder 21 and the inorganic fiber 22 and compression-molding them with a press or the like, for example, after forming the core material 2 in which the two core material layers 23 and 23 are laminated, In the same process as above, it is inserted into the outer cover material 3 which becomes an outer bag having excellent gas barrier properties, and after the drying process, the opening of the outer cover material 3 is sealed while reducing the pressure inside, thereby being sealed under reduced pressure. The

各芯材層２３は、厚さ方向の一方面側２３ａの無機繊維２２の含有率が厚さ方向他方面側２３ｂより小さく構成されている。芯材層２３の一方面側２３ａは、例えば表面側とされ、残りの裏面側が厚さ方向の他方面側２３ｂとなる。
なお、以下の説明では、芯材層２３の一方面側を表面側２３ａとし、他方面側を裏面側２３ｂとする。この表面側２３ａと裏面側２３ｂは、真空断熱材１の施工などの際の表裏とは、何ら関係がなく、説明上表裏とするものである。
すなわち、芯材層２３は、表面側（一方面側）２３ａの無機繊維２２の含有率が小さく、残りの部分の裏面側（厚さ方向他方面側）２３ｂの無機繊維２２の含有率が大きくなっている。 Each core material layer 23 is configured such that the content of the inorganic fibers 22 on the one surface side 23a in the thickness direction is smaller than that on the other surface side 23b in the thickness direction. One side 23a of the core material layer 23 is, for example, the front side, and the remaining back side is the other side 23b in the thickness direction.
In the following description, one side of the core material layer 23 is referred to as a front side 23a, and the other side is referred to as a back side 23b. The front surface side 23a and the back surface side 23b have nothing to do with the front and back when the vacuum heat insulating material 1 is constructed, and are front and back for explanation.
That is, the core layer 23 has a small content of the inorganic fibers 22 on the front surface side (one surface side) 23a and a large content of the inorganic fibers 22 on the back surface side (the other surface side in the thickness direction) 23b of the remaining portion. It has become.

芯材層２３を構成する無機粉末２１は、シリカ系粉末が好ましく、火炎法、アーク法、プラズマ法などの乾式法により製造される乾式シリカ、沈降法、ゲル法などの湿式法により製造される湿式シリカが挙げられる。また、無機粉末２１は、一次粒子径が小さいほど断熱性能が向上することから、シリカ系粉末の中でもフュームドシリカが好ましい。フュームドシリカは、平均一次粒子径がナノオーダーであること、また、フュームドシリカは、球状の一次粒子が数珠状に融着されており、空隙が微細であるため、経時断熱性能に優れる点でも好ましい。
特に、使用期間が長い建築用の真空断熱材１では、長期の断熱性能の安定性が求められることから、無機粉末２１としてフュームドシリカが好ましい。 The inorganic powder 21 constituting the core material layer 23 is preferably a silica-based powder, and manufactured by a dry method such as a flame method, an arc method, or a plasma method, or a wet method such as a sedimentation method or a gel method. Examples include wet silica. Further, the inorganic powder 21 is preferably fumed silica among the silica-based powders because the heat insulation performance is improved as the primary particle diameter is smaller. Fumed silica has an average primary particle size in the nano order, and fumed silica has spherical primary particles fused in a rosary shape and fine voids, so it has excellent heat insulation performance over time. However, it is preferable.
In particular, in the architectural vacuum heat insulating material 1 having a long use period, fumed silica is preferable as the inorganic powder 21 because stability of long-term heat insulating performance is required.

無機繊維２２は、グラスウール、グラスファイバー、シリカアルミナ繊維、シリカ繊維、アルミナ繊維、ロックウール、炭化ケイ素繊維などが挙げられる。
無機繊維２２を用いることで、アウトガスの発生を抑制することができる。
無機繊維２２は、繊維径が細いほど固体熱伝導を低減できることから、９μｍ以下が特に好ましい。繊維長さは、５〜１５ｍｍの範囲のものが好ましく、繊維長さが５ｍｍ未満では、芯材層２３の強度を確保することが不十分となり易く、１５ｍｍを超えて長くなると、無機粉末２１への分散性が悪くなり易い。 Examples of the inorganic fiber 22 include glass wool, glass fiber, silica alumina fiber, silica fiber, alumina fiber, rock wool, and silicon carbide fiber.
By using the inorganic fiber 22, generation of outgas can be suppressed.
The inorganic fiber 22 is particularly preferably 9 μm or less because the heat conduction can be reduced as the fiber diameter is thinner. The fiber length is preferably in the range of 5 to 15 mm. If the fiber length is less than 5 mm, it is difficult to ensure the strength of the core material layer 23, and if the fiber length exceeds 15 mm, the inorganic powder 21 is obtained. Dispersibility tends to deteriorate.

芯材層２３は、厚さ方向の一方面側である表面側２３ａの無機粉末２１への無機繊維２２の含有率が厚さ方向他方面側である残りの裏面側２３ｂより小さく構成されている。
こうすることで、芯材層２３の無機繊維２２の少ない層を表面側２３ａに設けることで、無機繊維２２による熱伝導を抑えて表面の無機繊維２２が熱橋の原因となることを防止する。一方、芯材層２３の残り部分の裏面側２３ｂの無機繊維２２の含有率を多くすることで芯材層２３の強度を十分確保できるようにしている。 The core material layer 23 is configured such that the content of the inorganic fibers 22 in the inorganic powder 21 on the surface side 23a that is one surface side in the thickness direction is smaller than the remaining back surface side 23b that is on the other surface side in the thickness direction. .
By carrying out like this, the layer with few inorganic fibers 22 of the core material layer 23 is provided in the surface side 23a, The heat conduction by the inorganic fibers 22 is suppressed and the surface inorganic fibers 22 are prevented from causing a thermal bridge. . On the other hand, the strength of the core material layer 23 can be sufficiently ensured by increasing the content of the inorganic fibers 22 on the back side 23 b of the remaining portion of the core material layer 23.

芯材層２３の無機繊維２２の含有率を小さくする厚さの範囲は、芯材層２３の表面から全厚さの２０％の範囲であり、板状の芯材層２３の一方面側である表面側２３ａは、芯材層２３の表面から２０％以下の厚さ部分である。
したがって、芯材層２３の無機繊維２２の含有率が大きい他方面側の残りの裏面側２３ｂは、芯材層２３の残りの８０％の厚さ部分となる。
無機繊維２２の含有率を小さくする厚さの範囲を、芯材層２３の表面からの２０％の厚さを超えて大きくすると、芯材層２３の表面の強度を確保することが難しくなり、外被材３内に入れて減圧密封する場合に、芯材層２３のひび割れの原因となる恐れがある。 The thickness range for reducing the content of the inorganic fibers 22 in the core material layer 23 is a range of 20% of the total thickness from the surface of the core material layer 23, and on one side of the plate-like core material layer 23. A certain surface side 23 a is a thickness portion of 20% or less from the surface of the core material layer 23.
Therefore, the remaining back surface side 23 b on the other surface side where the content of the inorganic fibers 22 in the core material layer 23 is large becomes the remaining 80% of the thickness portion of the core material layer 23.
If the thickness range for reducing the content of the inorganic fiber 22 is increased beyond the thickness of 20% from the surface of the core layer 23, it is difficult to ensure the strength of the surface of the core layer 23, When it is put in the jacket material 3 and sealed under reduced pressure, the core material layer 23 may be cracked.

芯材層２３の無機粉末２１への無機繊維２２の含有率は、一方面側である表面側２３ａの無機繊維２２の含有率が芯材層２３全体の無機繊維２２の含有率の半分以下で、かつ無機繊維２２の含有率は、５ｗｔ％以下とされる。
すなわち、各芯材層２３の無機繊維２２の総含有率が１０ｗｔ％を超えた場合には、一方面側である表面側２３ａの無機繊維２２の含有率は、総含有率１０ｗｔ％の半分の無機繊維２２の含有率が５ｗｔ％以上となることから、この場合には、最大でも５ｗｔ％までとする。
したがって、各芯材層２３の無機繊維２２の総含有率が１０ｗｔ％を超えるまでは、総含有率の半分（５ｗｔ％以下）の無機繊維２２が、一方面側である表面側２３ａに混合される。
一方面側である表面側２３ａの無機繊維２２の含有率が芯材層２３全体の無機繊維２２の含有率の半分以下で、かつ無機繊維２２の含有率の５ｗｔ％以下であれば、芯材層２３の一方面側である表面側２３ａの無機繊維２２が熱橋となることを抑えると同時に、成形体としての強度を確保することができる。
一方、一方面側である表面側２３ａの無機繊維２２の含有率が芯材層２３全体の無機繊維２２の含有率の半分以下であっても、無機繊維２２の含有率が５ｗｔ％を超えた場合には、無機繊維２２が熱橋となって断熱性能を低下させることになる。 The content of the inorganic fibers 22 in the inorganic powder 21 of the core material layer 23 is such that the content of the inorganic fibers 22 on the surface side 23a on one side is less than half of the content of the inorganic fibers 22 in the entire core material layer 23. And the content rate of the inorganic fiber 22 shall be 5 wt% or less.
That is, when the total content of the inorganic fibers 22 in each core material layer 23 exceeds 10 wt%, the content of the inorganic fibers 22 on the surface side 23 a that is one side is half of the total content 10 wt%. Since the content rate of the inorganic fiber 22 is 5 wt% or more, in this case, the content is set to 5 wt% at the maximum.
Therefore, until the total content of the inorganic fibers 22 in each core layer 23 exceeds 10 wt%, the inorganic fibers 22 that are half the total content (5 wt% or less) are mixed with the surface side 23 a that is one side. The
If the content rate of the inorganic fiber 22 on the surface side 23a on the one side is not more than half the content rate of the inorganic fiber 22 in the entire core material layer 23 and not more than 5 wt% of the content rate of the inorganic fiber 22, the core material While suppressing that the inorganic fiber 22 of the surface side 23a which is the one surface side of the layer 23 becomes a thermal bridge, the intensity | strength as a molded object is securable.
On the other hand, even if the content rate of the inorganic fiber 22 on the surface side 23a which is one side is less than or equal to half the content rate of the inorganic fiber 22 in the entire core layer 23, the content rate of the inorganic fiber 22 exceeded 5 wt%. In this case, the inorganic fiber 22 becomes a thermal bridge, and the heat insulation performance is reduced.

芯材層２３の層全体への無機繊維２２の含有率は、３０ｗｔ％以下、好ましくは、５〜１０ｗｔ％の範囲とする。芯材層２３の層全体の無機繊維２２の含有率を、例えば、３０ｗｔ％とする場合には、無機粉末２１の層全体の含有率は、７０ｗｔ％となり、無機繊維２２の層全体の含有率を、例えば、を５〜１０ｗｔ％の範囲とする場合には、無機粉末２１の層全体の含有率は、８５〜９０ｗｔ％の範囲となる。
無機繊維２２の層全体の含有率が３０ｗｔ％を超えて大きくなると、空隙が粗大化し、経時断熱性能が悪化する。また、無機繊維２２の層全体の含有率を５〜１０ｗｔ％の範囲とすることで、表面側２３ａの無機繊維２２による熱橋を抑制すると同時に、残りの裏面側２３ｂの強度を確保することを両立することができる。 The content of the inorganic fibers 22 in the entire core material layer 23 is 30 wt% or less, preferably 5 to 10 wt%. When the content rate of the inorganic fibers 22 in the entire core material layer 23 is, for example, 30 wt%, the content rate of the entire inorganic powder 21 layer is 70 wt%, and the content rate of the entire inorganic fiber 22 layer is 70 wt%. For example, when the content is in the range of 5 to 10 wt%, the content of the entire layer of the inorganic powder 21 is in the range of 85 to 90 wt%.
When the content rate of the whole layer of the inorganic fibers 22 exceeds 30 wt%, the voids become coarse and the temporal heat insulation performance deteriorates. Further, by setting the content of the entire layer of the inorganic fibers 22 in the range of 5 to 10 wt%, it is possible to suppress the thermal bridge by the inorganic fibers 22 on the front surface side 23a and at the same time ensure the strength of the remaining back surface side 23b. It can be compatible.

芯材層２３の密度は、１００〜３００kg/m3であることが好ましい。芯材層２３の密度がこの範囲であれば、粉末成形体である芯材層２３の十分な強度を確保することができる。
また、芯材層２３での空隙の粗大化を抑えることができる。 The density of the core material layer 23 is preferably 100 to 300 kg / m 3 . If the density of the core material layer 23 is within this range, sufficient strength of the core material layer 23 that is a powder molded body can be ensured.
Moreover, the coarsening of the space | gap in the core material layer 23 can be suppressed.

このような芯材層２３は、複数積層して芯材２とするが、各芯材層２３は、同一方向、すなわち表面側２３ａを上にした場合には、次の芯材層２３についても表面側２３ａを上にして積層する。
こうすることで、後述する芯材２の製造の際、無機粉末２１と無機繊維２２を混合し、均一に分散させた状態で成形型に入れ、加振することで、芯材層２３の表面側２３ａの無機繊維２２の含有率を小さく、残りの裏面側２３ｂの無機繊維２２の含有率を大きくする調整が簡単にできる。そして、加振したのち、プレス成形した芯材層２３の上に、同一の操作を繰り返すことで、次の芯材層２３をプレス成形して複数積層した芯材２を成形することができる。 A plurality of such core material layers 23 are laminated to form the core material 2. However, when each core material layer 23 is in the same direction, that is, when the surface side 23a is on the top, Laminate with the surface side 23a facing up.
By doing so, when the core material 2 described later is manufactured, the inorganic powder 21 and the inorganic fibers 22 are mixed, uniformly dispersed, put into a mold, and vibrated, whereby the surface of the core material layer 23 is obtained. Adjustment to decrease the content of the inorganic fibers 22 on the side 23a and increase the content of the inorganic fibers 22 on the remaining back surface 23b can be easily performed. Then, after the vibration, the same operation is repeated on the press-molded core material layer 23 to press-mold the next core material layer 23 to form a core material 2 in which a plurality of layers are stacked.

ここで、芯材層２３の表面側２３ａの無機繊維２２の含有率の調整は、次のようにして行うことができる。
芯材２の製造に用いる無機粉末２１と無機繊維２２とを用意し、無機粉末２１に対する無機繊維２２の含有率と芯材層２３の密度との関係を求める。
例えば、無機粉末２１としてヒュームドシリカ(１次粒子径が７〜１０ｎｍ)と、無機繊維２２としてガラス繊維(平均繊維径が５μｍ)を使って、ガラス繊維の含有率を１０ｗｔ％とし、このとき、ヒュームドシリカの含有率が９０ｗｔ％となるように配合し、混合ミキサーで２分間攪拌し、均一に分散させて混合物を得る。
続いて、得られた混合物を、２００×２００×１２ｍｍの芯材２となるように型枠内に、充填してプレス成形し、板状の芯材(繊維が均一分散状態)２を得る。
そして、得られた芯材２の重量と体積を計測し、計測値から密度を求める。
次に、無機繊維２２としてガラス繊維の含有率を２０ｗｔ％とし、このとき、ヒュームドシリカの含有率が８０ｗｔ％となるように配合し、同様にして、板状の芯材２を得、重量と体積から密度を求める。
さらに、無機繊維２２としてガラス繊維の含有率を３０ｗｔ％とし、このとき、ヒュームドシリカの含有率が７０ｗｔ％となるように配合し、同様にして、板状の芯材２を得、重量と体積から密度を求める。
こうして得られたガラス繊維の含有率(ｗｔ％)：１０ｗｔ％、２０ｗｔ％、３０ｗｔ％と、それぞれの密度(ｇ／ｃｍ３)から、図５に示す繊維含有率と密度の関係のグラフと下記の関係式を求めることができる。
ここで、横軸ｘは、繊維含有率（ｗｔ％）を、縦軸ｙは、密度（ｇ／ｃｍ３）を表す。
また、直線は、ｙ＝０．００４ｘ＋０．１０５８で表すことができる。
なお、このグラフおよび関係式は、一例に過ぎず、無機粉体２１であるシリカ系粉体や無機繊維２２の種類やシリカ系粉体の粒径や、無機繊維２２の径などによって、変わるものである。したがって、使用する無機粉体２１および無機繊維２２について求める必要がある。 Here, the content of the inorganic fibers 22 on the surface side 23a of the core material layer 23 can be adjusted as follows.
The inorganic powder 21 and the inorganic fiber 22 used for manufacturing the core material 2 are prepared, and the relationship between the content of the inorganic fiber 22 with respect to the inorganic powder 21 and the density of the core material layer 23 is obtained.
For example, fumed silica (primary particle diameter: 7 to 10 nm) is used as the inorganic powder 21 and glass fiber (average fiber diameter is 5 μm) is used as the inorganic fiber 22, and the glass fiber content is 10 wt%. The mixture is blended so that the fumed silica content is 90 wt%, stirred with a mixing mixer for 2 minutes, and uniformly dispersed to obtain a mixture.
Subsequently, the obtained mixture is filled into a mold so as to become a core material 2 of 200 × 200 × 12 mm and press-molded to obtain a plate-like core material (fibers in a uniformly dispersed state) 2.
And the weight and volume of the obtained core material 2 are measured, and a density is calculated | required from a measured value.
Next, the glass fiber content of the inorganic fibers 22 is set to 20 wt%, and at this time, the fumed silica content is blended to be 80 wt%, and the plate-like core material 2 is obtained in the same manner. And the density is calculated from the volume.
Further, the glass fiber content of the inorganic fiber 22 is set to 30 wt%, and at this time, the fumed silica content is set to 70 wt%. Similarly, the plate-like core material 2 is obtained, The density is obtained from the volume.
From the glass fiber content (wt%) thus obtained: 10 wt%, 20 wt%, and 30 wt%, and the respective densities (g / cm 3 ), the relationship between the fiber content and density shown in FIG. Can be obtained.
Here, the horizontal axis x represents the fiber content (wt%), and the vertical axis y represents the density (g / cm 3 ).
A straight line can be expressed by y = 0.004x + 0.1058.
The graph and the relational expression are merely examples, and change depending on the type of silica powder or inorganic fiber 22 that is the inorganic powder 21, the particle diameter of the silica powder, the diameter of the inorganic fiber 22, and the like. It is. Therefore, it is necessary to obtain the inorganic powder 21 and the inorganic fiber 22 to be used.

次に、芯材層２３の表面側（表面から２０％厚み）２３ａと残りの裏面側２３ｂの無機繊維２２の含有率は、上記の関係式を用いることで、算出することができる。
例えば、芯材２の厚みが１２ｍｍで、２層の芯材層２３，２３からなり、各芯材層２３において含有率差が存在するものでは、２層からなるため、各芯材層２３の厚みは、６ｍｍとなる。
したがって、各芯材層２３での表面から２０％厚みは、１．２ｍｍ、残りの８０％厚みは、４．８ｍｍとなる。
そこで、表面から２０％厚みの部分を削り取り、重量を測定する。
その結果、重量は、５．６５ｇ、体積は、２０×２０×０．１２＝４８ｃｍ３と求めることができる。
したがって、密度は、５．６５／４８=約０．１２ｋｇ／ｃｍ３となる。
得られた密度から、上記の関係式を用いて繊維含有率が約３ｗｔ％であると算出することができる。
同様に、芯材層２３の残りの裏面側２３ｂの重量を測定する。
その結果、重量が、２９．３４ｇ、体積は、２０×２０×０．４８＝１９２ｃｍ３と求められ、密度は、２９．３４／１９２＝約０．１５ｋｇ／ｃｍ３となる。
得られた密度から、上記の関係式を用いて繊維含有率が約１２ｗｔ％であると算出することができる。
以上のように、プレス成形後の芯材層２３の無機繊維２２の含有率を、表面側２３ａの無機繊維２２の含有率と、残りの裏面側２３ｂの無機繊維２２の含有率としてそれぞれ求めることができる。 Next, the content of the inorganic fibers 22 on the front surface side (20% thickness from the surface) 23a and the remaining back surface side 23b of the core material layer 23 can be calculated by using the above relational expression.
For example, if the thickness of the core material 2 is 12 mm, and the core material layer 23 includes two core material layers 23 and 23, and each core material layer 23 has a difference in content, the core material layer 23 includes two layers. The thickness is 6 mm.
Accordingly, the 20% thickness from the surface of each core layer 23 is 1.2 mm, and the remaining 80% thickness is 4.8 mm.
Therefore, a 20% thickness portion is scraped off from the surface and the weight is measured.
As a result, the weight can be obtained as 5.65 g and the volume as 20 × 20 × 0.12 = 48 cm 3 .
Therefore, the density is 5.65 / 48 = about 0.12 kg / cm 3 .
From the obtained density, it can be calculated that the fiber content is about 3 wt% using the above relational expression.
Similarly, the weight of the remaining back surface side 23b of the core material layer 23 is measured.
As a result, the weight is determined to be 29.34 g, the volume is determined to be 20 × 20 × 0.48 = 192 cm 3, and the density is 29.34 / 192 = about 0.15 kg / cm 3 .
From the obtained density, it can be calculated that the fiber content is about 12 wt% using the above relational expression.
As described above, the content of the inorganic fibers 22 in the core layer 23 after press molding is determined as the content of the inorganic fibers 22 on the front surface side 23a and the content of the inorganic fibers 22 on the remaining back surface side 23b. Can do.

次に、芯材２の製造の際の芯材層２３の表面から２０％厚みにおける繊維含有率を調整するために、加振機による加振時間と、繊維含有率との関係を予め求めた。
例えば、芯材２の厚みが１２ｍｍで、２層の芯材層２３からなる場合には、各芯材層２３の厚みは６ｍｍとなる。
そこで、芯材層２３の無機粉末２１として用いるヒュームドシリカ(１次粒子径が７〜１０ｎｍ)と、無機繊維２２として用いるガラス繊維(平均繊維径が５μｍ)を使って、ガラス繊維の含有率が１０ｗｔ％のとき、ヒュームドシリカが９０ｗｔ％となるように配合し、混合ミキサーで２分間攪拌し、均一に分散させて混合物を得る。
得られた混合物を、２００×２００×６ｍｍの芯材層２３となるように型枠内に充填し、加振機（振動条件：周波数１００Ｈｚ、振幅１０ｍｍ）で、加振時間を変えて振動を加え、プレス成形を行って芯材層２３を成形する。
得られた芯材層２３の表面側２３ａの部分を削り取り、すでに説明したように、密度を測定することで、得られた密度から、密度と繊維含有率の関係式を用いて無機繊維２２の含有率を、算出することができる。
したがって、芯材層２３とすべき、ある１つの繊維含有率の混合物に対して加振時間を変えることで、表面から２０％厚さの表面側２３ａの無機繊維２２の含有率を所定の値、例えば、３ｗｔ％とするための加振時間を、例えば、２１秒と求めることができる（後述の実施例１参照）。
なお、この加振時間と繊維含有率の関係は、無機粉体であるシリカ系粉体や無機繊維の種類やシリカ系粉体の粒径や、無機繊維の径などによって、変わるものであり、芯材層２３の厚さによっても変わるものである。
したがって、使用する無機粉体および無機繊維や芯材層の厚さ、加振条件などに対して求める必要がある。 Next, in order to adjust the fiber content at a thickness of 20% from the surface of the core material layer 23 in the production of the core material 2, the relationship between the excitation time by the vibrator and the fiber content was obtained in advance. .
For example, when the core material 2 has a thickness of 12 mm and is composed of two core material layers 23, the thickness of each core material layer 23 is 6 mm.
Therefore, using fumed silica (primary particle diameter of 7 to 10 nm) used as the inorganic powder 21 of the core material layer 23 and glass fiber (average fiber diameter of 5 μm) used as the inorganic fiber 22, the glass fiber content rate Is 10 wt%, fumed silica is blended so as to be 90 wt%, stirred for 2 minutes with a mixing mixer, and uniformly dispersed to obtain a mixture.
The obtained mixture is filled into a mold so as to be a core layer 23 of 200 × 200 × 6 mm, and vibration is generated by changing the excitation time with a vibrator (vibration condition: frequency 100 Hz, amplitude 10 mm). In addition, the core material layer 23 is formed by press molding.
The part of the surface side 23a of the obtained core material layer 23 is scraped off, and as described above, by measuring the density, the relation between the density and the fiber content of the inorganic fiber 22 is obtained from the obtained density. The content rate can be calculated.
Therefore, the content of the inorganic fibers 22 on the surface side 23a having a thickness of 20% from the surface is changed to a predetermined value by changing the excitation time for a certain fiber content mixture to be the core layer 23. For example, the vibration time for 3 wt% can be obtained as, for example, 21 seconds (see Example 1 described later).
The relationship between the vibration time and the fiber content varies depending on the type of inorganic powder, silica-based powder and inorganic fiber, silica-based powder particle diameter, inorganic fiber diameter, and the like. It varies depending on the thickness of the core material layer 23.
Therefore, it is necessary to determine the thickness of the inorganic powder and inorganic fiber or core layer used, the vibration conditions, and the like.

同様な実験を予め行うことで、芯材層２３の層全体への無機繊維２２の含有率を１０ｗｔ％とし、芯材層２３の全体の厚さを１２ｍｍとして３層で構成した場合に、表面から２０％厚みにおける繊維含有率を約３％にするための加振時間は、２０秒と算出することができた（後述の実施例２参照）。
また、芯材層２３の層全体への無機繊維２２の含有率を１０ｗｔ％とし、芯材層２３の全体の厚さを１２ｍｍとして４層で構成した場合に、表面から２０％厚みにおける繊維含有率を約３％にするための加振時間は、１９秒と算出することができた（後述の実施例３参照）。
さらに、芯材層２３の層全体への無機繊維２２の含有率を５ｗｔ％とし、芯材層２３の全体の厚さを１２ｍｍとして３層で構成した場合に、表面から２０％厚みにおける繊維含有率を約２％にするための加振時間は、１０秒と算出することができた（後述の実施例４参照）。 By performing the same experiment in advance, the surface ratio of the inorganic fiber 22 in the entire core material layer 23 is set to 10 wt%, and the total thickness of the core material layer 23 is 12 mm. The vibration time for making the fiber content at 20% thickness about 3% was calculated as 20 seconds (see Example 2 described later).
Moreover, when the content rate of the inorganic fiber 22 in the whole layer of the core material layer 23 is 10 wt%, and the total thickness of the core material layer 23 is 12 mm, the fiber content is 20% from the surface. The excitation time for setting the rate to about 3% could be calculated as 19 seconds (see Example 3 described later).
Furthermore, when the content rate of the inorganic fibers 22 in the entire layer of the core material layer 23 is 5 wt%, and the total thickness of the core material layer 23 is 12 mm, the fiber content is 20% from the surface. The excitation time for setting the rate to about 2% could be calculated as 10 seconds (see Example 4 described later).

このような無機粉末２１と無機繊維２２とを均一に分散させた状態の混合物を用いて、型枠内に充填し、予め得られた加振時間加振することで、表面から２０％厚さの表面側２３ａの無機繊維２２の含有率を所定の値にした芯材層２３を１回のプレスで成形することができる。   Using a mixture in which such inorganic powder 21 and inorganic fiber 22 are uniformly dispersed, the mold is filled into the mold, and is vibrated for a predetermined period of time to obtain a thickness of 20% from the surface. The core material layer 23 in which the content of the inorganic fibers 22 on the surface side 23a is set to a predetermined value can be formed by a single press.

なお、１つの芯材層２３に対して、表面側２３ａの無機繊維２２の含有率に応じた無機繊維２２を均一に分散させた混合物と、残りの裏面側２３ｂの無機繊維２２の含有率に応じた無機繊維２２を均一に分散させた混合物との２つの混合物を用意しておき、それぞれを型枠内に充填してプレス成形するようにしても良い。   In addition, with respect to one core material layer 23, the content of the inorganic fibers 22 on the back surface side 23b and the mixture in which the inorganic fibers 22 according to the content rate of the inorganic fibers 22 on the front surface side 23a are uniformly dispersed are It is also possible to prepare two mixtures with a mixture in which the corresponding inorganic fibers 22 are uniformly dispersed, fill each in a mold and press-mold them.

このような真空断熱材１によれば、芯材２と、芯材２を覆う外被材３とを有し、外被材３の内部を減圧密封した真空断熱材１で、芯材２を、無機粉末２１と無機繊維２２とを混合して圧縮成形した２層の芯材層２３を積層して構成し、各芯材層２３を、厚さ方向の一方面側２３ａの無機繊維２２の含有率を厚さ方向他方面側２３ｂより小さく構成したので、一方面側である表面側２３ａの無機繊維２２が熱橋となることを抑えることができ、他方面側である残りの裏面側２３ｂの含有率の大きい無機繊維２２によって強度を確保することができる。
また、芯材２を２つの芯材層２３で構成したので、それぞれの芯材層２３の表面側２３ａの厚さを単層の芯材に比べて薄くすることができ、粉末成形体としての強度を確保することが容易になる。 According to such a vacuum heat insulating material 1, the core material 2 is formed by the vacuum heat insulating material 1 having the core material 2 and the outer cover material 3 covering the core material 2, and the inside of the outer cover material 3 is sealed under reduced pressure. The two core material layers 23 formed by mixing and compressing the inorganic powder 21 and the inorganic fibers 22 are laminated, and each core material layer 23 is formed of the inorganic fibers 22 on one surface side 23a in the thickness direction. Since the content rate is configured to be smaller than the other surface side 23b in the thickness direction, the inorganic fiber 22 on the surface side 23a that is one surface side can be prevented from becoming a thermal bridge, and the remaining back surface side 23b that is the other surface side. The strength can be ensured by the inorganic fibers 22 having a large content ratio.
In addition, since the core material 2 is composed of the two core material layers 23, the thickness of the surface side 23a of each core material layer 23 can be made thinner than that of a single-layer core material. It becomes easy to ensure strength.

次に、本発明の真空断熱材の他の実施の形態について、説明する。
真空断熱材１Ａは、図３に示すように、芯材２として３層の芯材層２３を備えて構成されている。
この真空断熱材１Ａの厚さは、既に説明した真空断熱材１と同一とされ、その結果、各層の芯材層２３の厚さが芯材２の厚さの１/３の厚さとしてある。
芯材層２３は、厚さが異なるものの、表面側２３ａの無機繊維２２の含有率は、小さくされ、残りの裏面側２３ｂの無機繊維２２の含有率が大きくしてある。
また、表面側２３ａは、芯材層２３の表面から２０％の範囲とされ、残りの８０％の厚さ部分を裏面側２３ｂとする構成や無機繊維２２の含有率についても同一の範囲とされ、真空断熱材１と同一である。
このような真空断熱材１Ａによれば、既に説明した真空断熱材１と同一の効果を奏するとともに、芯材２を３層の芯材層２３で構成することで、熱伝導率を小さくして断熱性能を向上することができる。
また、各芯材層２３の厚さが２層の場合に比べ、さらに薄くなっているため、それぞれの芯材層２３の表面側２３ａの粉末成形体としての強度を確保することが一層容易になる。 Next, another embodiment of the vacuum heat insulating material of the present invention will be described.
As shown in FIG. 3, the vacuum heat insulating material 1 </ b> A includes three core material layers 23 as the core material 2.
The thickness of the vacuum heat insulating material 1A is the same as that of the vacuum heat insulating material 1 already described. As a result, the thickness of the core material layer 23 of each layer is 1/3 of the thickness of the core material 2. .
Although the core layer 23 is different in thickness, the content of the inorganic fibers 22 on the front surface side 23a is reduced, and the content of the inorganic fibers 22 on the remaining back surface side 23b is increased.
Moreover, the surface side 23a is made into the range of 20% from the surface of the core material layer 23, and the structure which makes the remaining 80% thickness part the back side 23b, and the content rate of the inorganic fiber 22 are also made into the same range. This is the same as the vacuum heat insulating material 1.
According to such a vacuum heat insulating material 1A, while exhibiting the same effect as the vacuum heat insulating material 1 which has already been described, the core material 2 is composed of three core material layers 23, thereby reducing the thermal conductivity. Thermal insulation performance can be improved.
Further, since the thickness of each core material layer 23 is further thinner than that in the case of two layers, it is easier to ensure the strength of the surface side 23a of each core material layer 23 as a powder compact. Become.

真空断熱材１Ｂは、図４に示すように、芯材２として４層の芯材層２３を備えて構成されている。
この真空断熱材１Ｂの厚さは、既に説明した真空断熱材１、１Ａと同一とされ、その結果、各層の芯材層２３の厚さが芯材２の厚さの１/４の厚さとしてある。
芯材層２３は、厚さが異なるものの、表面側２３ａの無機繊維２２の含有率は、小さくされ、残りの裏面側２３ｂの無機繊維２２の含有率が大きくしてある。
また、表面側２３ａは、芯材層２３の表面から２０％の範囲とされ、残りの８０％の厚さ部分を裏面側２３ｂとする構成や無機繊維２２の含有率についても同一の範囲とされ、真空断熱材１と同一である。
このような真空断熱材１Ｂによれば、既に説明した真空断熱材１と同一の効果を奏するとともに、芯材２を４層の芯材層２３で構成することで、熱伝導率を一層小さくして断熱性能を向上することができる。
また、各芯材層２３の厚さが２層や３層の場合に比べ、さらに薄くなっているため、それぞれの芯材層２３の表面側２３ａの粉末成形体としての強度を確保することが一層容易になる。 As shown in FIG. 4, the vacuum heat insulating material 1 </ b> B is configured to include four core material layers 23 as the core material 2.
The thickness of the vacuum heat insulating material 1B is the same as that of the vacuum heat insulating materials 1 and 1A already described. As a result, the thickness of the core material layer 23 of each layer is 1/4 of the thickness of the core material 2. It is as.
Although the core layer 23 is different in thickness, the content of the inorganic fibers 22 on the front surface side 23a is reduced, and the content of the inorganic fibers 22 on the remaining back surface side 23b is increased.
Moreover, the surface side 23a is made into the range of 20% from the surface of the core material layer 23, and the structure which makes the remaining 80% thickness part the back side 23b, and the content rate of the inorganic fiber 22 are also made into the same range. This is the same as the vacuum heat insulating material 1.
According to such a vacuum heat insulating material 1B, while exhibiting the same effect as the vacuum heat insulating material 1 already demonstrated, the thermal conductivity is made still smaller by comprising the core material 2 with the four core material layers 23. Heat insulation performance can be improved.
Moreover, since the thickness of each core material layer 23 is further thinner than in the case of two or three layers, it is possible to ensure the strength of the surface side 23a of each core material layer 23 as a powder compact. It becomes easier.

なお、上記の真空断熱材１Ａ，１Ｂでは、真空断熱材１と同一の厚さとして芯材層２３の厚さを変えるようにしたが、真空断熱材１Ａや真空断熱材１Ｂの厚さを変えて構成するようにしても良く、厚さによって得られる熱伝導率も変化することから必要な断熱性能に応じて決定すれば良い。   In the vacuum heat insulating materials 1A and 1B, the thickness of the core material layer 23 is changed to the same thickness as the vacuum heat insulating material 1, but the thickness of the vacuum heat insulating material 1A and the vacuum heat insulating material 1B is changed. The thermal conductivity obtained by the thickness varies depending on the thickness, and may be determined according to the required heat insulation performance.

このような真空断熱材１,１Ａ，１Ｂによれば、芯材２と、芯材２を覆う外被材３とを有し、外被材３の内部を減圧密封した真空断熱材１で、芯材２を、無機粉末２１と無機繊維２２とを混合して圧縮成形した複数の芯材層２３を積層して構成し、各芯材層２３を、厚さ方向の一方面側２３ａの無機繊維２２の含有率を厚さ方向他方面側２３ｂより小さく構成したので、一方面側である表面側２３ａの無機繊維２２が熱橋となることを抑えることができ、他方面側である残りの裏面側２３ｂの含有率の大きい無機繊維２２によって強度を確保することができる。
また、芯材２を複数の芯材層２３で構成したので、それぞれの芯材層２３の表面側２３ａの厚さを単層の芯材に比べて薄くすることができ、粉末成形体としての強度を確保することが容易になる。 According to such vacuum heat insulating materials 1, 1 </ b> A, 1 </ b> B, the vacuum heat insulating material 1 having the core material 2 and the outer cover material 3 covering the core material 2, and the inside of the outer cover material 3 being sealed under reduced pressure, The core material 2 is formed by laminating a plurality of core material layers 23 formed by mixing inorganic powder 21 and inorganic fibers 22 and compression-molding, and each core material layer 23 is made of an inorganic material on one side 23a in the thickness direction. Since the content rate of the fiber 22 is configured to be smaller than the other side 23b in the thickness direction, the inorganic fiber 22 on the surface side 23a that is one side can be prevented from becoming a thermal bridge, and the remaining side that is on the other side The strength can be ensured by the inorganic fibers 22 having a large content on the back surface side 23b.
Moreover, since the core material 2 is composed of a plurality of core material layers 23, the thickness of the surface side 23a of each core material layer 23 can be made thinner than that of a single-layer core material. It becomes easy to ensure strength.

また、真空断熱材１,１Ａ，１Ｂによれば、芯材層２３は、一方面側である表面側２３ａの無機繊維２２の含有率を、芯材層２３全体の無機繊維２２の含有率の半分以下で、かつ無機繊維２２の含有率を５ｗｔ％以下としたので、一方面側である表面側２３ａの無機繊維２２が熱橋となることを抑えることができ、他方面側である残りの裏面側２３ｂの含有率の大きい無機繊維２２によって強度を確保することができる。   Moreover, according to the vacuum heat insulating materials 1, 1 </ b> A, and 1 </ b> B, the core material layer 23 has a content ratio of the inorganic fibers 22 on the surface side 23 a that is one side of the core material layer 23. Since it is less than half and the content of the inorganic fiber 22 is 5 wt% or less, the inorganic fiber 22 on the surface side 23a on one side can be prevented from becoming a thermal bridge, and the remaining on the other side The strength can be ensured by the inorganic fibers 22 having a large content on the back surface side 23b.

真空断熱材１,１Ａ，１Ｂによれば、芯材層２３は、芯材層２３全体の無機繊維２２の含有率を５〜１０ｗｔ％の範囲としたので、表面側２３ａの無機繊維２２による熱橋の抑制と同時に、残りの裏面側２３ｂの強度の確保を両立することができる。   According to the vacuum heat insulating materials 1, 1A and 1B, the core material layer 23 has the content of the inorganic fibers 22 in the entire core material layer 23 in the range of 5 to 10 wt%, so the heat by the inorganic fibers 22 on the surface side 23a. Simultaneously with the suppression of the bridge, it is possible to ensure the strength of the remaining back surface side 23b.

真空断熱材１,１Ａ，１Ｂによれば、芯材層２３は、一方面側である表面側２３ａの厚さが芯材層２３全体の厚さの２０％以下であるので、表面側２３ａの無機繊維２２による熱橋の抑制と同時に、残りの裏面側２３ｂの強度の確保を一層確実に両立させることができる。   According to the vacuum heat insulating materials 1, 1 </ b> A, and 1 </ b> B, the thickness of the surface side 23 a that is one side of the core material layer 23 is 20% or less of the total thickness of the core material layer 23. Simultaneously with the suppression of the thermal bridge by the inorganic fibers 22, it is possible to more surely ensure the strength of the remaining back surface side 23b.

真空断熱材１,１Ａ，１Ｂによれば、芯材層２３を、厚さ方向の一方面側である表面側２３ａと他方面側である残りの裏面側２３ｂとを同一方向として積層して構成したので、芯材２の製造の際、無機粉末２１と無機繊維２２を混合し、均一に分散させた状態で成形型に入れ、加振することで、芯材層２３の表面側２３ａの無機繊維２２の含有率を小さく、残りの裏面側２３ｂの無機繊維２２の含有率を大きくする調整が簡単にできる。   According to the vacuum heat insulating materials 1, 1A, 1B, the core material layer 23 is formed by laminating the surface side 23a that is one side in the thickness direction and the remaining back side 23b that is the other side in the same direction. Therefore, when the core material 2 is manufactured, the inorganic powder 21 and the inorganic fibers 22 are mixed, put in a uniformly dispersed state, and vibrated, so that the inorganic material on the surface side 23a of the core material layer 23 is obtained. Adjustment which makes small the content rate of the fiber 22 and makes the content rate of the inorganic fiber 22 of the remaining back side 23b large can be performed easily.

以下、本発明の実施例を比較例とともに、具体的に説明する。
ここでは、次のようにして真空断熱体を作製し、熱伝導率と強度を評価した。
（熱伝導率）
熱伝導率は、真空断熱材の初期値、７０℃の環境下で３ヶ月経過後の値をそれぞれ測定した。
なお、測定は、２０×２０ｃｍ角の試料を作成し、オートラムダＨＣ−０７４（英弘精機製）を使用して測定した。
なお、参考のため、熱伝導率の劣化率を算出した。
（強度）
強度は、芯材層を積層した芯材を外被材に入れて真空パックした際の芯材のひび割れの有無で評価した。
○は、ひび割れなし
×は、ひび割れあり、である。 Examples of the present invention will be specifically described below together with comparative examples.
Here, a vacuum heat insulator was produced as follows, and thermal conductivity and strength were evaluated.
(Thermal conductivity)
As the thermal conductivity, an initial value of the vacuum heat insulating material and a value after three months in an environment of 70 ° C. were measured.
In addition, the measurement produced the sample of a 20 * 20 cm square, and measured using auto-lambda HC-074 (made by Eihiro Seiki).
For reference, the deterioration rate of thermal conductivity was calculated.
(Strength)
The strength was evaluated based on the presence or absence of cracks in the core material when the core material on which the core material layer was laminated was put into a jacket material and vacuum packed.
○: no cracks ×: cracks.

（実施例１）
実施例１では、真空断熱材１を２０×２０ｃｍ角で厚さを１２ｍｍとし、芯材２を２層の芯材層２３で構成した。
無機粉末２１としてヒュームドシリカ(１次粒子径が７〜１０ｎｍ)と、無機繊維２２としてガラス繊維(平均繊維径が５μｍ)を使って、ガラス繊維の含有率を１０ｗｔ％とし、このときのヒュームドシリカの含有率が９０ｗｔ％となるように配合し、混合ミキサーで２分間攪拌し、均一に分散させて混合物を得る。
続いて、得られた混合物を型枠内に、２００×２００×６ｍｍの芯材層２３となるように充填して、加振機（振動条件：周波数１００Ｈｚ、振幅１０ｍｍ）で、予め得られた加振時間を２１秒として振動を加えたのち、プレス成形を行って１層目の芯材層２３を成形した。
こうして得られた芯材層２３は、表面側２３ａの無機繊維２２の含有率が約３ｗｔ％となる。
続いて、型枠内の１層目の芯材層２３の上に、均一に分散させた混合物を充填し、加振時間を２１秒として加振したのち、プレス成形を行って２層目の厚さが６ｍｍの芯材層２３を成形した。
こうして２層の芯材層２３を積層した厚さ１２ｍｍの芯材２を得たのち、アルミ蒸着系複層フィルムの袋状の外被材３で覆い、乾燥の工程を経て、内部を減圧しながら開口部をシールして真空断熱材１を作製した。
この真空断熱材１では、その結果を、表１中に示すように、熱伝導率は、初期値が、０．００５５１Ｗ／ｍ・Ｋ、３ヶ月経過後の値が０．００５９８Ｗ／ｍ・Ｋであり、強度は、ひび割れなしの○であった。 Example 1
In Example 1, the vacuum heat insulating material 1 was 20 × 20 cm square, the thickness was 12 mm, and the core material 2 was composed of two core material layers 23.
The fumed silica (primary particle diameter is 7 to 10 nm) as the inorganic powder 21 and the glass fiber (average fiber diameter is 5 μm) as the inorganic fiber 22 and the glass fiber content is 10 wt%. It mix | blends so that the content rate of dosilica may be 90 wt%, it stirs for 2 minutes with a mixing mixer, and disperse | distributes uniformly, and obtains a mixture.
Subsequently, the obtained mixture was filled into a mold so as to be a core layer 23 of 200 × 200 × 6 mm, and obtained in advance with a vibrator (vibration conditions: frequency 100 Hz, amplitude 10 mm). After applying vibration with an excitation time of 21 seconds, press forming was performed to form the first core material layer 23.
The core material layer 23 thus obtained has a content of the inorganic fibers 22 on the surface side 23a of about 3 wt%.
Subsequently, the uniformly dispersed mixture is filled on the first core material layer 23 in the mold, and after shaking is performed for 21 seconds, press molding is performed to perform the second layer. A core material layer 23 having a thickness of 6 mm was formed.
After obtaining the core material 2 having a thickness of 12 mm in which the two core material layers 23 are laminated in this way, the core material 2 is covered with a bag-like outer covering material 3 of an aluminum vapor deposition type multilayer film, and the inside is decompressed through a drying process. The opening was sealed while the vacuum heat insulating material 1 was produced.
In this vacuum heat insulating material 1, as shown in Table 1, the thermal conductivity has an initial value of 0.00551 W / m · K and a value after 3 months of 0.00598 W / m · K. The strength was ◯ without cracks.

（実施例２）
実施例２では、真空断熱材１Ａを２０×２０ｃｍ角で厚さを１２ｍｍとし、芯材２を３層の芯材層２３で構成した。
各芯材層２３の厚さが４ｍｍとなることから、型枠内に充填した混合物の加振時間を、予め求めた２０秒として、芯材層２３の表面から２０％の範囲の無機繊維２２の含有率が３ｗｔ％となるようにした以外は、実施例１と同一である。
この真空断熱材１Ａでは、その結果を、表１中に示すように、熱伝導率は、初期値が、０．００５２６Ｗ／ｍ・Ｋ、３ヶ月経過後の値が０．００５７１Ｗ／ｍ・Ｋであり、強度は、ひび割れなしの○であった。 (Example 2)
In Example 2, the vacuum heat insulating material 1A was 20 × 20 cm square, the thickness was 12 mm, and the core material 2 was composed of three core material layers 23.
Since the thickness of each core layer 23 is 4 mm, the excitation time of the mixture filled in the mold is set to 20 seconds, which is determined in advance, and the inorganic fibers 22 are within a range of 20% from the surface of the core layer 23. Example 1 is the same as Example 1 except that the content of is 3 wt%.
In this vacuum heat insulating material 1A, as shown in Table 1, the thermal conductivity is 0.00526 W / m · K at an initial value of 0.00526 W / m · K, and the value after 3 months is 0.00571 W / m · K. The strength was ◯ without cracks.

（実施例３）
実施例３では、真空断熱材１Ｂを２０×２０ｃｍ角で厚さを１２ｍｍとし、芯材２を４層の芯材層２３で構成した。
各芯材層２３の厚さが３ｍｍとなることから、型枠内に充填した混合物の加振時間を、予め求めた１９秒として、芯材層２３の表面から２０％の範囲の無機繊維２２の含有率が３ｗｔ％となるようにした以外は、実施例１と同一である。
この真空断熱材１Ｂでは、その結果を、表１中に示すように、熱伝導率は、初期値が、０．００５１６Ｗ／ｍ・Ｋ、３ヶ月経過後の値が０．００５５９Ｗ／ｍ・Ｋであり、強度は、ひび割れなしの○であった。 (Example 3)
In Example 3, the vacuum heat insulating material 1B was 20 × 20 cm square, the thickness was 12 mm, and the core material 2 was composed of four core material layers 23.
Since the thickness of each core material layer 23 is 3 mm, the inorganic fiber 22 in the range of 20% from the surface of the core material layer 23 is set to 19 seconds as the vibration time of the mixture filled in the mold. Example 1 is the same as Example 1 except that the content of is 3 wt%.
In this vacuum heat insulating material 1B, as shown in Table 1, the thermal conductivity is 0.00516 W / m · K at an initial value of 0.00516 W / m · K, and the value after 3 months is 0.00559 W / m · K. The strength was ◯ without cracks.

（実施例４）
実施例４では、真空断熱材１Ａを２０×２０ｃｍ角で厚さを１２ｍｍとし、芯材２を３層の芯材層２３で構成した。
無機粉末２１としてヒュームドシリカ(１次粒子径が７〜１０ｎｍ)と、無機繊維２２としてガラス繊維(平均繊維径が５μｍ)を使って、ガラス繊維の含有率を５ｗｔ％とし、このときのヒュームドシリカの含有率が９５ｗｔ％となるように配合し、混合ミキサーで２分間攪拌し、均一に分散させて混合物を得る。
続いて、得られた混合物を型枠内に、２００×２００×４ｍｍの芯材層２３となるように充填して、加振機（振動条件：周波数１００Ｈｚ、振幅１０ｍｍ）で、予め得られた加振時間を１０秒として振動を加えたのち、プレス成形を行って１層目の芯材層２３を成形した。
こうして得られた芯材層２３は、表面側２３ａの無機繊維２２の含有率が約２ｗｔ％となる。
続いて、型枠内の１層目の芯材層２３の上に、均一に分散させた混合物を充填し、加振時間を１０秒として加振したのち、プレス成形を行って２層目の厚さが４ｍｍの芯材層２３を成形した。同様にして、３層目を成形した。
こうして３層の芯材層２３を積層した厚さ１２ｍｍの芯材２を得たのち、アルミ蒸着系複層フィルムの袋状の外被材３で覆い、乾燥の工程を経て、内部を減圧しながら開口部をシールして真空断熱材１Ａを作製した。
この真空断熱材１Ａでは、その結果を、表１中に示すように、熱伝導率は、初期値が、０．００５３８Ｗ／ｍ・Ｋ、３ヶ月経過後の値が０．００５８４Ｗ／ｍ・Ｋであり、強度は、ひび割れなしの○であった。 Example 4
In Example 4, the vacuum heat insulating material 1A was 20 × 20 cm square, the thickness was 12 mm, and the core material 2 was composed of three core material layers 23.
Using fumed silica (primary particle diameter of 7 to 10 nm) as the inorganic powder 21 and glass fiber (average fiber diameter of 5 μm) as the inorganic fiber 22, the glass fiber content is 5 wt%. It mix | blends so that the content rate of dosilica may be 95 wt%, and it stirs for 2 minutes with a mixing mixer, and disperse | distributes uniformly, and obtains a mixture.
Subsequently, the obtained mixture was filled into a mold so as to be a core layer 23 of 200 × 200 × 4 mm, and obtained in advance with a vibrator (vibration conditions: frequency 100 Hz, amplitude 10 mm). After applying vibration with an excitation time of 10 seconds, press forming was performed to form the first core material layer 23.
The core material layer 23 thus obtained has a content of the inorganic fibers 22 on the surface side 23a of about 2 wt%.
Subsequently, the uniformly dispersed mixture is filled on the first core material layer 23 in the mold, and after shaking for 10 seconds, the second layer is subjected to press molding. A core material layer 23 having a thickness of 4 mm was formed. Similarly, the third layer was molded.
In this way, after obtaining the core material 2 having a thickness of 12 mm in which the three core material layers 23 are laminated, the core material 2 is covered with a bag-like outer covering material 3 of an aluminum vapor deposition-type multilayer film, and the interior is decompressed through a drying process. The opening was sealed while producing a vacuum heat insulating material 1A.
In this vacuum heat insulating material 1A, as shown in Table 1, the thermal conductivity is 0.00538 W / m · K at an initial value of 0.00538 W / m · K, and the value after 3 months is 0.00584 W / m · K. The strength was ◯ without cracks.

（比較例１）
比較例１では、真空断熱材を２０×２０ｃｍ角で厚さを１２ｍｍとし、芯材を単層で構成した。
無機粉末２１としてヒュームドシリカ(１次粒子径が７〜１０ｎｍ)と、無機繊維２２としてガラス繊維(平均繊維径が５μｍ)を使って、ガラス繊維の含有率を１０ｗｔ％とし、このときのヒュームドシリカの含有率が９０ｗｔ％となるように配合し、混合ミキサーで２分間攪拌し、均一に分散させて混合物を得る。
続いて、得られた混合物を型枠内に、２００×２００×１２ｍｍの芯材となるように充填して、プレス成形した。
こうして得られた芯材は、無機繊維２２が均一に分散された状態である。
厚さ１２ｍｍの芯材を、アルミ蒸着系複層フィルムの袋状の外被材で覆い、乾燥の工程を経て、内部を減圧しながら開口部をシールして真空断熱材を作製した。
この真空断熱材では、その結果を、表１中に示すように、熱伝導率は、初期値が、０．００６１１Ｗ／ｍ・Ｋ、３ヶ月経過後の値が０．００６６２Ｗ／ｍ・Ｋであり、真空断熱材として必要な断熱性能を確保できなかった。強度は、ひび割れなしの○であった。 (Comparative Example 1)
In Comparative Example 1, the vacuum heat insulating material was 20 × 20 cm square, the thickness was 12 mm, and the core material was a single layer.
The fumed silica (primary particle diameter is 7 to 10 nm) as the inorganic powder 21 and the glass fiber (average fiber diameter is 5 μm) as the inorganic fiber 22 and the glass fiber content is 10 wt%. It mix | blends so that the content rate of dosilica may be 90 wt%, it stirs for 2 minutes with a mixing mixer, and disperse | distributes uniformly, and obtains a mixture.
Subsequently, the obtained mixture was filled into a mold so as to be a core material of 200 × 200 × 12 mm, and press-molded.
The core material thus obtained is in a state where the inorganic fibers 22 are uniformly dispersed.
A core material having a thickness of 12 mm was covered with a bag-shaped outer cover material of an aluminum-deposited multilayer film, and after a drying process, the opening was sealed while the inside was decompressed to produce a vacuum heat insulating material.
In this vacuum heat insulating material, as shown in Table 1, the thermal conductivity is 0.00611 W / m · K at the initial value of 0.00611 W / m · K, and the value after 3 months is 0.00662 W / m · K. Yes, it was not possible to ensure the heat insulation performance required as a vacuum heat insulating material. The strength was ○ without cracks.

（比較例２）
比較例２では、真空断熱材を２０×２０ｃｍ角で厚さを１２ｍｍとし、芯材を単層で構成した。
無機粉末２１としてヒュームドシリカ(１次粒子径が７〜１０ｎｍ)と、無機繊維２２としてガラス繊維(平均繊維径が５μｍ)を使って、ガラス繊維の含有率を５ｗｔ％とし、このときのヒュームドシリカの含有率が９５ｗｔ％となるように配合し、混合ミキサーで２分間攪拌し、均一に分散させて混合物を得る。
続いて、得られた混合物を型枠内に、２００×２００×１２ｍｍの芯材となるように充填して、プレス成形した。
こうして得られた芯材は、無機繊維２２が均一に分散された状態である。
厚さ１２ｍｍの芯材を、アルミ蒸着系複層フィルムの袋状の外被材で覆い、乾燥の工程を経て、内部を減圧しながら開口部をシールして真空断熱材を作製した。
この真空断熱材では、その結果を、表１中に示すように、熱伝導率は、初期値が、０．００５８１Ｗ／ｍ・Ｋ、３ヶ月経過後の値が０．００６３１Ｗ／ｍ・Ｋであり、真空断熱材として必要な断熱性能を確保できなかった。強度は、ひび割れなしの○であった。 (Comparative Example 2)
In Comparative Example 2, the vacuum heat insulating material was 20 × 20 cm square, the thickness was 12 mm, and the core material was a single layer.
Using fumed silica (primary particle diameter of 7 to 10 nm) as the inorganic powder 21 and glass fiber (average fiber diameter of 5 μm) as the inorganic fiber 22, the glass fiber content is 5 wt%. It mix | blends so that the content rate of dosilica may be 95 wt%, and it stirs for 2 minutes with a mixing mixer, and disperse | distributes uniformly, and obtains a mixture.
Subsequently, the obtained mixture was filled into a mold so as to be a core material of 200 × 200 × 12 mm, and press-molded.
The core material thus obtained is in a state where the inorganic fibers 22 are uniformly dispersed.
A core material having a thickness of 12 mm was covered with a bag-shaped outer cover material of an aluminum-deposited multilayer film, and after a drying process, the opening was sealed while the inside was decompressed to produce a vacuum heat insulating material.
In this vacuum heat insulating material, as shown in Table 1, the thermal conductivity is 0.00581 W / m · K at an initial value of 0.00581 W / m · K, and the value after 3 months is 0.00631 W / m · K. Yes, it was not possible to ensure the heat insulation performance required as a vacuum heat insulating material. The strength was ○ without cracks.

Figure 2016037973
Figure 2016037973

１ 真空断熱材
１Ａ 真空断熱材
１Ｂ 真空断熱材
２ 芯材
３ 外被材
２１ 無機粉末
２２ 無機繊維
２３ 芯材層
２３ａ 表面側（一方面側）
２３ｂ 裏面側（他方面側） DESCRIPTION OF SYMBOLS 1 Vacuum heat insulating material 1A Vacuum heat insulating material 1B Vacuum heat insulating material 2 Core material 3 Cover material 21 Inorganic powder 22 Inorganic fiber 23 Core material layer 23a Surface side (one surface side)
23b Back side (the other side)

Claims (5)

芯材と、前記芯材を覆う外被材とを有し、前記外被材の内部を減圧密封した真空断熱材であって、
前記芯材は、無機粉末と無機繊維とを混合して圧縮成形した複数の芯材層を積層して構成し、
前記各芯材層は、厚さ方向の一方面側の前記無機繊維の含有率が厚さ方向他方面側より小さく構成される、
ことを特徴とする真空断熱材。 A vacuum insulating material having a core material and a jacket material covering the core material, wherein the inside of the jacket material is sealed under reduced pressure,
The core material is constituted by laminating a plurality of core material layers obtained by mixing and compressing inorganic powder and inorganic fibers,
Each core layer is configured such that the content of the inorganic fiber on one side in the thickness direction is smaller than that on the other side in the thickness direction.
Vacuum insulation characterized by that. 前記芯材層は、前記一方面側の前記無機繊維の含有率が前記芯材層全体の前記無機繊維の含有率の半分以下で、かつ前記無機繊維の含有率は、５ｗｔ％以下である、
ことを特徴とする請求項１に記載の真空断熱材。 The core material layer has a content of the inorganic fiber on the one surface side that is less than or equal to half of the content of the inorganic fiber in the entire core material layer, and the content of the inorganic fiber is 5 wt% or less.
The vacuum heat insulating material according to claim 1. 前記芯材層は、前記芯材層全体の前記無機繊維の含有率が５〜１０ｗｔ％の範囲である、
ことを特徴とする請求項１または２に記載の真空断熱材。 In the core material layer, the content of the inorganic fibers in the entire core material layer is in the range of 5 to 10 wt%.
The vacuum heat insulating material according to claim 1 or 2, characterized by the above. 前記芯材層は、前記一方面側の厚さが前記芯材層全体の厚さの２０％以下である、
ことを特徴とする請求項１乃至３のいずれかに記載の真空断熱材。 The core material layer has a thickness on the one surface side of 20% or less of the total thickness of the core material layer.
The vacuum heat insulating material according to any one of claims 1 to 3. 前記芯材層は、厚さ方向の前記一方面側と前記他方面側とを同一方向として積層されている、
ことを特徴とする請求項１乃至４のいずれかに記載の真空断熱材。 The core material layer is laminated with the one surface side in the thickness direction and the other surface side in the same direction,
The vacuum heat insulating material according to claim 1, wherein:
JP2014159483A 2014-08-05 2014-08-05 Vacuum heat insulation material Pending JP2016037973A (en)

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