阅读说明：本技术 绝热片及其制造方法、电子设备和电池单元 (Heat insulating sheet, method for manufacturing same, electronic device, and battery cell ) 是由 和田享 酒谷茂昭 及川一摩 久保隆志 于 2020-01-23 设计创作，主要内容包括：本发明涉及绝热片及其制造方法、电子设备和电池单元。本发明提供即使在高载荷下也能够使用的绝热片及其制造方法和电子设备。使用一种绝热片,其包含气凝胶和无纺布纤维,且在0.30～5.0MPa下的压缩率为40％以下、压缩时的热阻为0.01m<Sup>2</Sup>K/W以上。使用一种绝热片的制造方法,其包括：复合体生成工序,使向水玻璃组合物中添加碳酸酯而制作的溶胶浸渗至上述无纺布纤维结构体,从而生成水凝胶-无纺布纤维的复合体；表面修饰工序,将上述复合体进行水洗处理后,与甲硅烷基化剂混合而进行表面修饰；以及干燥工序,通过以低于临界温度和压力的条件进行干燥而去除上述复合体中所含的液体。使用一种电子设备,其在壳体与伴有发热的电子部件之间配置有上述绝热片。(The invention relates to a heat insulating sheet, a method of manufacturing the same, an electronic device, and a battery unit. The invention provides a heat insulating sheet which can be used even under a high load, a method for manufacturing the same, and an electronic device. A heat insulating sheet comprising aerogel and nonwoven fabric fibers, having a compressibility of 40% or less under 0.30 to 5.0MPa and a thermal resistance of 0.01m when compressed 2 K/W is higher than the above. A manufacturing method using a thermal insulation sheet, comprising: a complex formation step ofImpregnating the nonwoven fabric fiber structure with a sol prepared by adding a carbonate to a water glass composition to produce a hydrogel-nonwoven fabric fiber composite; a surface modification step of washing the composite with water and then mixing the washed composite with a silylation agent to modify the surface of the composite; and a drying step of removing the liquid contained in the composite by drying under a condition of a temperature and a pressure lower than a critical temperature and a pressure. An electronic device is used in which the heat insulating sheet is disposed between a case and an electronic component that generates heat.)

1. A method of manufacturing a thermal insulation sheet comprising:

a composite-forming step of forming a hydrogel-nonwoven-fabric-fiber composite by impregnating nonwoven fabric fibers with an alkaline sol having a pH of 10 or more, the alkaline sol being prepared by adding 1 to 10 parts by weight of a carbonate as a gelling agent other than a solvent to a water glass composition;

a surface modification step of mixing the composite with a silylating agent to modify the surface of the composite; and

and a drying step of removing the liquid contained in the composite by drying.

2. The method for producing a heat-insulating sheet according to claim 1, wherein in the composite-forming step, SiO in the water-glass composition₂The concentration is 14 to 22 wt%.

3. The method of manufacturing a thermal insulation sheet according to claim 1, wherein the nonwoven fabric fibers are inorganic fibers.

4. The method of manufacturing a thermal insulation sheet according to claim 1, wherein in the composite forming step, the carbonate is soluble in water and is easily hydrolyzed under an alkaline condition at a pH of 10 or more to form carbonate ions and glycol.

5. The method of manufacturing a heat insulating sheet according to claim 1, wherein in the surface modification step, a water washing step is performed before the composite is surface-modified with a silylating agent.

6. The method of manufacturing a heat insulating sheet according to claim 5, wherein the surface finishing step is performed by erecting the composite at an angle of 90 degrees ± 45 degrees with respect to a bottom surface of a treatment tank.

7. The method of manufacturing a heat insulating sheet according to claim 1, wherein in the surface modification step, the composite is stood up at an angle of 90 degrees ± 30 degrees with respect to a bottom surface of a treatment tank, and is subjected to a hydrochloric acid dipping treatment.

8. The method of manufacturing a heat insulating sheet according to claim 1, wherein in the surface modification step, the composite is erected at an angle of 90 degrees ± 45 degrees with respect to a bottom surface of a treatment tank to perform silylation treatment.

9. A thermal insulation sheet comprising aerogel and nonwoven fabric fibers, wherein the thermal insulation sheet has a compressibility of 40% or less at 0.30 to 5.0 MPa.

10. The thermal insulation sheet according to claim 9, which has a thermal resistance of 0.01m when compressed at 0.30 to 5.0MPa²K/W is higher than the above.

11. The thermal insulation sheet according to claim 9, wherein the aerogel has a specific surface area of 300m²More than g and 600m²Less than 1.5ml/g of pore volume.

12. The thermal insulation sheet according to claim 9, wherein the bulk density of the thermal insulation sheet is 0.3g/cm³Above and 0.5g/cm³The following.

13. The thermal insulation sheet according to claim 9, wherein the thickness variation of the thermal insulation sheet is 0.040mm or less.

14. An electronic device, wherein the heat insulating sheet according to claim 9 is disposed between a case and an electronic component accompanied by heat generation.

15. A battery cell in which the thermal insulating sheet according to claim 9 is disposed between batteries.

Technical Field

The invention relates to a heat insulating sheet, a method of manufacturing the same, and an electronic apparatus. And more particularly to a high-strength heat insulating sheet, a method of manufacturing the same, an electronic apparatus, and a battery cell.

Background

In the field of vehicle-mounted and industrial equipment, a high-performance heat insulating sheet having excellent compression characteristics is required to ensure control of heat flow from a heat generating component in a narrow space, safety of products, and resistance to ignition. Such a heat insulating sheet is expected to be applied to, for example, a spacer between battery cells of a lithium ion battery module.

In the safety standards for lithium ion batteries, a burn-up resistance test was performed. The burn-resistant test is a method for testing whether a thermal runaway in one of the battery cells in the battery module causes an ignition or a rupture due to thermal interlocking with other battery cells including adjacent battery cells.

In order to prevent thermal runaway to adjacent battery cells, there is an idea of a safety design in which a material having excellent thermal insulation is sandwiched between the battery cells. In theory, even a material having a high thermal conductivity to some extent can prevent thermal interlocking and ignition to some extent by increasing the thickness.

However, since the battery module is disposed within the device, a floor space is limited in practice. Therefore, the battery module has a size limit.

Furthermore, even when the battery module is intended to have a high capacity, there is a difficulty in that both the prevention of the burn-up and the miniaturization are required.

In order to achieve these properties, a thin material having high thermal insulation properties is desired for the spacer between the battery cells. When it is assumed that the active material is deteriorated and expands during charge and discharge cycles of the battery to cause expansion of the battery cell, it is desirable that the heat-insulating sheet also have a property of being less likely to be crushed (ulceration れる).

That is, although the load applied to the thermal insulation sheet as the spacer between the battery cells is relatively small, 1MPa or less, at the time of initial assembly of the battery module, a load of about 5MPa may be applied at the maximum when the battery expands. Therefore, it is important to design the material of the thermal insulation sheet in consideration of the compression characteristics.

As a substance having a small thermal conductivity, silica aerogel is known. The silica aerogel has a network structure in which silica particles of 10nm order are connected in point contact, and the average pore diameter is 68nm or less of the average free path of air.

Thus, the thermal conductivity of silica aerogel is less than that of still air. Therefore, silica aerogel attracts attention as an excellent heat insulating material. However, silica aerogel is regarded as a practical problem in that it has extremely low strength against various deformation modes such as compression, bending, shearing, and the like.

Patent document 1 discloses a thin and homogeneous sheet-like heat insulating material in which silica aerogel and nonwoven fabric fibers are combined to improve handling properties. The thin heat insulating sheet is excellent in handling property and strong in bendability.

Disclosure of Invention

Problems to be solved by the invention

However, when the conventional heat insulating sheet is used by being sandwiched between battery cells or the like, particularly under a high load, the aerogel is compressed and crushed, and the heat insulating effect is significantly reduced as compared with that under a low load.

Accordingly, an object of the present invention is to provide a heat insulating sheet that can be used even under a high load, a method for manufacturing the same, an electronic device, and a battery cell.

Means for solving the problems

In order to solve the above problems, a method for producing a heat insulating sheet, comprising: a composite-forming step of impregnating the nonwoven fabric fiber structure with a sol prepared by adding a carbonate to a water glass composition to form a hydrogel-nonwoven fabric fiber composite; a surface modification step of mixing the composite with a silylating agent to modify the surface of the composite; and a drying step of removing the liquid contained in the composite by drying under a condition of a temperature and a pressure lower than a critical temperature and a pressure.

Further, by using a carbonate as a gelling agent, sodium carbonate is produced as a by-product in the aerogel, carbon dioxide is generated in the silylation process, and this is a factor of reducing the compressibility performance, but this carbon dioxide can be effectively removed by treating the aerogel in a vertical manner by the water washing step.

Further, a heat insulating sheet is used, which comprises aerogel and nonwoven fabric fibers, and has a compressibility of 40% or less at 0.30 to 5.0MPa and a thermal resistance of 0.01m²K/W is higher than the above.

Further, an electronic device is used in which the heat insulating sheet is disposed between a case and an electronic component that generates heat.

Further, a battery unit in which the above-described heat insulating sheet is disposed between batteries is used.

Effects of the invention

The high-strength heat-insulating sheet of the present embodiment has a compressibility of 40% or less at 5MPa and is less likely to be crushed, and has a thermal resistance of 0.01m at 5MPa²K/W or more, and therefore, an effective heat conduction delaying effect is exhibited even in a high-temperature compression environment.

Drawings

FIG. 1 is a chemical formula diagram illustrating a mechanism of gelation of water glass based on a carbonate ester according to an embodiment.

Fig. 2 is a flowchart of a method for manufacturing a high-strength heat-insulating sheet according to an embodiment.

Fig. 3 is a diagram showing the arrangement of sheets in water washing of the heat-insulating sheet according to the embodiment.

Fig. 4 is a diagram showing the arrangement of sheets in the hydrochloric acid aqueous solution immersion of the heat insulating sheet of the embodiment.

Fig. 5 is a diagram showing the arrangement of sheets in the silylation treatment of the thermal insulation sheet according to the embodiment.

FIG. 6 is a SiO diagram of a water glass according to an embodiment₂Graph of concentration versus compressibility of the insulation sheet.

FIG. 7 is a SiO diagram of a water glass according to an embodiment₂Graph of concentration versus thermal resistance of the insulation sheet.

FIG. 8 is a SiO diagram of a water glass according to an embodiment₂A graph of concentration versus thermal conductivity of the insulation sheet.

FIG. 9 is a SiO diagram of a water glass according to an embodiment₂A graph of concentration versus bulk density of the insulation.

FIG. 10 is a SiO diagram of a water glass according to an embodiment₂Graph of concentration versus specific surface area of aerogel.

FIG. 11 is a SiO diagram of a water glass according to an embodiment₂Graph of concentration versus pore volume of aerogel.

FIG. 12 is a SiO diagram of a water glass according to an embodiment₂Graph of concentration versus average pore diameter of aerogels.

FIG. 13 is a SiO diagram of a water glass showing an embodiment₂A graph of the concentration versus the compressibility of the insulation sheet at each pressing pressure.

Fig. 14 is a sectional view showing application example 1 of the heat insulating sheet of the embodiment.

Fig. 15 is a sectional view showing application example 2 of the heat insulating sheet of the embodiment.

Description of the reference numerals

10 Heat insulation sheet

11 casing

12 electronic component

13 substrate

15 cell

51 Heat insulating sheet

52 sodium carbonate

53 carbon dioxide

54 hydrochloric acid

55 rinsing bath

56 Water

57 hydrochloric acid tank

58 hydrochloric acid

59 silylation tank

60 silylating agent

101 sodium silicate

102 hydroxyl ion

103 ethylene carbonate

104 carbonate ion

105 ethylene glycol

106 hydrogel

107 sodium carbonate

Detailed Description

The present embodiment will be described below by referring to preferred embodiments of the invention.

< design concept of high-strength thermal insulation sheet >

Several aerogel composite insulation sheets comprising silica aerogel and nonwoven fibers have been known to date. Most of them are gradually improved in handling property. However, the strength capable of withstanding compression of 5MPa and the 0.01m under compression have not been achieved at the same time²High thermal resistance value of K/W or more.

The high-strength heat-insulating sheet according to the present embodiment is a heat-insulating sheet containing at least two components of a high-density aerogel and a nonwoven fabric fiber structure. Here, the thermal insulation sheet of the present embodiment has high strength. This is due to the "high-density aerogel" which is composed densely and without gaps in the gaps of the continuous nonwoven fabric fibrous body.

Generally, silica aerogel refers to a low density porous silica body having a bulk density of less than about 0.3g/cm³. Inorganic acids and bases such as low-concentration silica raw materials and gelling agents, for example, alkoxysilane and water glass, are generally used for the synthesis. Here, in the case of water glass, there is a restriction that the concentration of silica used for synthesis of aerogel is 6 wt% or less. This is because: when an inorganic acid or an organic acid is added as a gelling agent, hydrolysis and dehydration condensation of sodium silicate rapidly proceed, and the reaction rate is too high at a silica concentration of 7 wt% or more to induce non-uniform nucleation, and a uniform gel cannot be obtained.

Here, the gelling agent means a catalyst for making a sol into a hydrogel.

Therefore, in the conventional aerogel synthesis method, the silica concentration cannot be increased, and a high-density aerogel cannot be obtained. In addition, the strength of the aerogel cannot be improved by densifying the aerogel.

< compression characteristics of high-strength thermal insulation sheet >

The compressibility of the thermal insulation sheet of the present embodiment when pressurized at 0.30 to 5MPa is preferably 40% or less, and more preferably 30% or less.

< thermal resistance of high-strength insulating sheet >

The thermal insulation sheet of the present embodiment preferably has a thermal resistance of 0.010m when pressurized at 0.30MPa to 5MPa²K/W or more, and more preferably 0.015m or more²K/W is higher than the above.

< thermal conductivity of Heat-insulating sheet >

The thermal conductivity of the thermal insulation sheet of the present embodiment cannot be generally defined depending on the magnitude of the compression ratio, and may be 100mW/mK or less.

< bulk Density of Heat-insulating sheet >

The bulk density of the thermal insulation sheet of the present embodiment is preferably 0.3g/cm³～0.5g/cm³。

< pore characteristics of aerogel >

The specific surface area of the high-density aerogel of the present embodiment is preferably 300m²/g～600m²(ii) in terms of/g. The average pore diameter of the high-density aerogel is preferably 10-70 nm.

< raw Material types and silica concentrations of aerogels >

As a raw material of the high-density aerogel, a general-purpose silica raw material such as alkoxysilane or water glass can be used. The dispersion or solution is prepared for use by adding water in such a manner as to achieve the desired silica concentration.

It is considered that Na ions affect densification and densification of the porous structure in the high-density aerogel, and therefore, water glass containing Na ions is suitably used. The higher the silica concentration in the raw material dispersion or solution is, the better the synthesis of the high-density aerogel, and preferably 14 to 20% by weight is.

< gelling agent for synthetic aerogels and concentration thereof >

The present inventors have intensively studied a gelling agent for synthesizing a novel aerogel capable of uniformly gelling a high-concentration silica raw material of 8 wt% or more. As a result, they found that: the carbonates can uniformly gelatinize the high-concentration water glass raw material, and are suitable for synthesizing high-density aerogel.

The high-density aerogel of the present embodiment uses carbonate as a gelling agent. It is known that carbonates are generally strongly acidic, but hydrolyze under basic conditions to carbonic acid and alcohol. In the present embodiment, the carbonic acid produced by the hydrolysis is used for gelation.

The mechanism of gelation of water glass by carbonate is described with reference to the chemical structure diagram of fig. 1, taking ethylene carbonate as an example.

As a first step, when ethylene carbonate 103 is added to and dissolved in an aqueous solution of alkaline sodium silicate 101 having a pH of 10 or more, hydroxyl ions 102 in the raw material nucleophilically attack the carbonyl carbon of ethylene carbonate 103, thereby hydrolyzing ethylene carbonate 103.

As a result, carbonate ions 104 and ethylene glycol 105 are generated in the system.

In the second step, sodium silicate 101 reacts with carbonate ions 104 to perform a dehydration condensation reaction of silicic acid. At this time, sodium carbonate 107 is produced as a by-product. When the network structure including siloxane bonds is expanded, the fluidity of the water glass is lost and gelation occurs. This operation gave hydrogel 106. Most of the sodium carbonate 107 remains in the hydrogel 106.

As described above, in the case of using carbonate as the gelling agent, the reaction proceeds in two stages, and thus it is characterized in that the reaction rate of the hydrolysis and dehydration condensation reaction of the sodium silicate 101 can be controlled, and uniform gelling can be achieved.

As the kind of the carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, ethyl methyl carbonate, ethylene carbonate, propylene carbonate, or the like can be used. Any carbonate can uniformly gel a high-concentration silica raw material, but if the alkyl chain of the carbonate is long, hydrophobicity becomes strong, and it is difficult to dissolve the carbonate in a water glass aqueous solution. Therefore, dimethyl carbonate and ethylene carbonate, which are relatively easily soluble in water, are preferably used from the viewpoint of solubility of the carbonate in water and the hydrolysis reaction rate.

When the amount of the carbonate added is 0.5 to 10.0 parts by weight based on the total amount (100 parts by weight) of the silica raw material, a uniform gel can be produced. The gelling time varies depending on the silica concentration and the gelling agent concentration, and is preferably 3.0 to 6.0 parts by weight from the viewpoints of productivity (speed of impregnation of the raw material liquid into the nonwoven fabric, etc.) and the cost of the gelling agent.

It is noted that the carbonate is a gelling agent, not a solvent.

< thickness of Heat-insulating sheet >