JP6920580B2 - Insulated windows and how to make them - Google Patents

Description

The present invention relates to a heat insulating structure and a method for manufacturing the same.

As an excellent heat insulating structure, there is a heat insulating window using airgel (Patent Document 1). This heat insulating window is made by inserting particulate airgel between two pieces of glass.

Japanese Unexamined Patent Publication No. 11-30805

However, in this insulated window, there is a layer of air in addition to airgel. As a result, it was transmitted through the air and the heat insulation performance was poor.

Therefore, an object of the present invention is to provide a heat insulating structure containing airgel without an air layer and a method for producing the same.

In order to achieve the above object, a heat insulating structure including a first member, a second member, and an airgel film formed between the first member and the second member is used.

Further, a heat insulating structure including a step of applying a sol on the first member, a step of gelling the sol into a gel, a step of hydrophobizing the gel, and a step of drying the gel to form an airgel film. Use the body manufacturing method.

According to the present invention, a heat insulating structure having excellent heat insulating performance can be realized.

Cross-sectional view of the heat insulating structure of the first embodiment (A)-(d) Cross-sectional view showing the manufacturing method of the heat insulating structure of the first embodiment. Cross-sectional view of the heat insulating structure of the second embodiment Cross-sectional view of the heat insulating structure of the third embodiment (A) Cross-sectional view of the heat insulating structure of the fourth embodiment, (b) perspective view of the airgel membrane of the fourth embodiment.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 shows a cross-sectional view of the heat insulating structure 10a of the first embodiment.
The airgel film 13 is arranged between the second member 12 and the first member 11.
The airgel film 13 is a layer of airgel. It is a film-like layer made of airgel, not airgel particles. This is a membrane prepared by applying a sol solution as a raw material for airgel.

The heat of the heat source 55 is insulated by this heat insulating structure 10a.

A method of manufacturing the heat insulating structure 10a will be described with reference to the cross-sectional views of FIGS. 2A to 2D.

FIG. 2A is a cross section of the first member 11. In FIG. 2B, the following sol solution 15 is applied from the nozzle 18 onto the first member 11.

<Sol solution 15>
To 22.29 parts by weight of a high molar silicic acid aqueous solution ( _{Tosso Sangyo Co., Ltd., SiO 2} concentration 14% by weight), 0.31 parts by weight (1.4% by weight) of concentrated hydrochloric acid was added as a catalyst, and the mixture was stirred to make a sol solution 15. To formulate.

The raw material species of silica is not limited to high molar sodium silicate, and alkoxysilane or water glass (low molar ratio) may be used. A high-molar silicic acid aqueous solution is _{a silica raw material in which the particle size distribution of primary particles of SiO 2} is in the range of about 2 to 20 nm and is located in an intermediate size between water glass and colloidal silica, and has a higher sodium component than ordinary water glass. It is reduced to 1% by weight or less.

The SiO ₂ concentration is preferably 10% by weight or more in order to maintain the strength of the silica xerogel. _{The SiO 2} concentration is preferably 16% by weight or less in order to reduce the heat transfer component of the solid and reduce the thermal conductivity. It is preferable to add an acid catalyst in order to promote the hydrolysis reaction of silicic acid in the high molar silicic acid aqueous solution.

The types of acids used include hydrochloric acid, nitric acid, sulfuric acid, hydrofluoric acid, sulfite, phosphoric acid, phosphite, hypophosphoric acid, chloric acid, chloric acid, hypochlorous acid and other inorganic acids, and acidic phosphoric acid. Examples thereof include acidic phosphates such as aluminum, acidic magnesium phosphate and acidic zinc phosphate, and organic acids such as acetic acid, propionic acid, oxalic acid, succinic acid, citric acid, malic acid, adipic acid and azelaic acid. The type of acid catalyst used is not limited, but hydrochloric acid is preferable from the viewpoint of gel skeleton strength and hydrophobicity of the obtained silica xerogel.

The acid concentration is preferably 1 to 12N, more preferably 6 to 12N in the case of hydrochloric acid, for example. When the acid concentration is less than 1N, it is necessary to add a larger amount of dilute hydrochloric acid when adjusting the high molar silicic acid aqueous solution to a desired pH. Therefore, the concentration of silicic acid may decrease, and the construction of the silica network may not proceed effectively.

When the acid concentration is 6N or more, for example, the addition amount is one-sixth that of the case where 1N hydrochloric acid is added, and it is possible to avoid a decrease in the _{SiO 2 concentration.}

The amount of the acid catalyst added depends on the pH value to be adjusted, but is preferably 0.5 to 6.0 parts by weight in the case of a 12N hydrochloric acid aqueous solution with respect to 100 parts by weight of the hydrogel in the case of hydrochloric acid. 0 to 3.0 parts by weight is more preferable.

Next, after a lapse of time after FIG. 2 (b), the sol solution 15 is flattened on the first member 11 as shown in FIG. 2 (c). The first member 11 may be rotated to flatten the sol solution 15 by leveling.

<Gelization>
Then, the sol solution 15 is gelled to obtain a gel 25.

The sol solution 15 prepared by adding the above acid catalyst to a high molar silicic acid aqueous solution is gelled. The gelation of the sol solution 15 is preferably performed in a closed container so that the liquid solvent does not volatilize.

When an acid is added to a high molar silicic acid aqueous solution to gel the sol solution 15, the pH value at that time is preferably 4.0 to 8.0. If the pH is less than 4.0 or greater than 8.0, the high molar silicic acid aqueous solution may not gel, depending on the temperature at that time.

The gelling temperature of the sol solution is preferably 0 to 100 ° C., more preferably 20 to 90 ° C. under normal pressure.

If the gelation temperature is less than 0 ° C., the heat required for the silicic acid monomer, which is the active species of the reaction, is not transferred. As a result, the growth of silica particles is not promoted, and it takes time for the gelation of the sol solution to proceed sufficiently. In addition, the resulting wet gel has low strength and may shrink significantly during drying. In addition, the desired silica xerogel may not be obtained.

Further, when the gelation temperature exceeds 100 ° C., a phenomenon is observed in which water volatilizes in the container and separates from the gel even if the container is sealed. As a result, the volume of the wet gel obtained is reduced, and the desired silica xerogel may not be obtained.

When the gelation temperature is in the range of 20 to 90 ° C., gelation can be promoted by moderate growth of silica particles and formation of a silica network without impairing productivity. Further, it is more preferable because gelation can be induced without volatilizing the water content of the wet gel.

The gelation time differs depending on the gelation temperature and the curing time after gelation, which will be described later. However, the total gelling time and the curing time described later are preferably 0.5 to 72 hours, more preferably 2 to 24 hours.

By gelling and curing in this way, the strength and rigidity of the wall of the gel 25 are improved, and a wet gel 25 that does not easily shrink during drying can be obtained.

If the total time of gelation and curing is less than 0.5 hours, the improvement of the strength of the wall of the gel 25 may be insufficient.

On the other hand, if the total time of gelation and curing is longer than 72 hours, the effect of curing in improving the strength of the gel wall is poor, and on the contrary, productivity may be impaired. It is more preferable that the total gelling time and curing time is 2 to 24 hours because the strength of the wall of the gel 25 can be sufficiently improved without impairing the productivity.

<Cure>
The first member 11 having the gel 25 of FIG. 2C is placed in a constant temperature and humidity chamber having a temperature of 85 ° C. and a humidity of 85% for 3 hours. This causes the silica particles to grow (dehydration condensation reaction of silanol) to form a porous structure.

The curing temperature is preferably 50 to 100 ° C., more preferably 60 to 90 ° C. under normal pressure.

If the curing temperature is less than 50 ° C., the heat required for the silicic acid monomer, which is the active species of the reaction, is not transferred and the growth of silica particles is not promoted, as in the gelation step. As a result, it takes time for the curing to proceed sufficiently, and the strength of the wet gel produced is low. Furthermore, it may shrink significantly when dried, and the desired silica xerogel may not be obtained.

Further, when the curing temperature exceeds 100 ° C., even if the container is sealed, a phenomenon is observed in which water volatilizes in the container and separates from the gel. As a result, the volume of the wet gel obtained is reduced, and the desired silica xerogel may not be obtained.

On the other hand, when the curing temperature is in the range of 60 to 90 ° C., the appropriate growth of the silica particles can be promoted without impairing the productivity. Further, it is possible to strengthen the neck portion in which the silica particles are connected by point contact. Moreover, it is possible to carry out curing without volatilizing the water content of the wet gel.

The curing time depends on the curing temperature, but is preferably 0.5 to 6 hours, more preferably 1 to 3 hours.

If the curing time is less than 0.5 hours, the strength of the gel wall may not be sufficiently improved.

If the curing time exceeds 6 hours, the curing effect of improving the strength of the gel wall becomes poor, and conversely, the productivity is impaired.

If the curing time is 1 to 3 hours, the strength of the gel wall can be sufficiently improved without impairing the productivity.

As the curing conditions, the curing temperature, the curing humidity, and the curing time must be considered as a set. Considering the balance between the improvement of gel skeleton strength and productivity, the curing time is preferably 1 to 3 hours under the conditions of 85 ° C. and 85%.

In order to increase the pore volume of xerogel and increase the average pore diameter, the gelation temperature and curing temperature should be increased within the above range, or the total time of gelation time and curing time should be increased within the above range. Is preferable.

Further, in order to reduce the pore volume of the silica xerogel and the average pore diameter, the gelation temperature and the curing temperature should be lowered within the above range, and the total time of the gelation time and the curing time should be within the above range. It is preferable to shorten it within.

<Hydrophobicization 1 (hydrochloric acid immersion process)>
After immersing the first member 11 in FIG. 2C after curing in hydrochloric acid (specified in 6 to 12), the mixture is left at room temperature of 23 ° C. for 45 minutes or more to incorporate hydrochloric acid into the gel.

<Hydrophobicization 2 (siloxane treatment process)>
The first member 11 in FIG. 2C after hydrophobization 1 is immersed in, for example, a mixed solution of octamethyltrisiloxane as a silylating agent and 2-propanol (IPA) as an alcohol, and placed in a constant temperature bath at 55 ° C. Add and react for 2 hours.

When the trimethylsiloxane bond begins to form, hydrochloric acid water is discharged from the gel, and the two liquids are separated. Siloxane is mainly distributed in the upper layer, and hydrochloric acid water and 2-propanol are mainly distributed in the lower layer.

<Drying>
After the hydrophobization 2, the first member 11 of FIG. 2C is transferred to a constant temperature bath at 150 ° C. and dried for 2 hours. The film of the airgel film 13 is completed.

<Lasting>
The second member 12 is placed on the gel 25 on the first member 11 of FIG. 2C after drying. Complete by sealing the surroundings.

<Effect>
Since the airgel film 13 is formed directly on the first member 11, the first member 11 and the airgel film 13 have good adhesion. As a result, heat conduction can be reliably prevented without gaps.

When the second member 12 and the first member 11 are made of glass, the heat insulating structure 10a becomes a heat insulating window.

(Embodiment 2)
FIG. 3 shows a cross-sectional view of the heat insulating structure 10b of the second embodiment. Matters not described are the same as those in the first embodiment.

The heat insulating structure 10b of the second embodiment has a spacer 41 on the airgel film 13. In FIG. 2B, a plurality of spacers 41 are arranged on the first member 11 before the sol solution 15 is applied to the first member 11. After that, when the sol solution 15 is applied, the sol solution 15 is held between the spacers 41, and the film thickness of the sol solution 15 becomes constant. The resulting airgel 35 has a constant thickness. Further, the space between the second member 12 and the first member 11 is maintained at a uniform distance by the spacer 41.

The distance between the second member 12 and the first member 11 becomes constant, and the heat insulating performance becomes higher.

(Embodiment 3)
FIG. 4 shows a cross-sectional view of the heat insulating structure 10c of the third embodiment. Matters not described are the same as those in the first embodiment.

The heat insulating structure 10c of the third embodiment has a coating film 42 on one surface of the airgel film 13. In FIG. 2D, the covering film 42 is arranged instead of the second member 12.

The coating film 42 differs depending on the application. Fluororesin is used for applications in contact with acid and alkaline solutions. When in contact with a thermal fluid, a heat resistant film or the like is used.
As the heat-resistant coating, Ceracoat (trademark) of Odec Co., Ltd. may be used. It has heat resistance of 1000 ° C to 1500 ° C.

(Embodiment 4)
FIG. 5A shows a cross-sectional view of the heat insulating structure 10d according to the fifth embodiment. Matters not described are the same as those in the first embodiment.

The heat insulating structure 10d of the fourth embodiment is an example of a pipeline and has the shape of a cylindrical tube. A liquid such as petroleum flows through the heat source 55. The heat insulating structure 10d is a structure that heats the heat source 55.

There is a second member 52 around the heat source 55, an airgel film 13 on the outside thereof, and a first member 51 on the outside thereof. The second member 52 and the first member 51 have similar shapes. The shape may not be tubular but may be a closed shape.

The production method is the same as that of the first embodiment, but since the first member 51 has a cylindrical shape, it is necessary to make the surface of the surface of the first member 51 on which the airgel film 13 is formed porous to hold the sol solution 15. .. Subsequent steps are the same as in the first embodiment.

As another method, the airgel sheet 23 shown in the perspective view of FIG. 5B can be used. The airgel sheet 23 is obtained by applying the sol solution 15 to a porous sheet such as a fiber sheet, gelling, curing, hydrophobizing, and drying. The airgel sheet 23 can be attached to the first member 51.

(as a whole)
The second member 12 is not essential. The airgel film second member 12 and the first member 11 may be a metal material, a ceramic material, a resin, a plastic, or silicon.

The manufacturing method of airgel is an example, and other manufacturing methods may be used.

The heat insulating structure of the present invention can be used as various windows such as automobile windows and building windows. It can also be applied to thermal structures that transport and handle thermal fluids such as pipes and pipes.

10a Insulation structure 10b Insulation structure 10c Insulation structure 10d Insulation structure 11 1st member 12 2nd member 13 Aerogel film 14 Concentration 15 Sol solution 18 Nozzle 23 Aerogel sheet 25 Gel 35 Aerogel 41 Spacer 42 Coating film 51 1st Member 52 Second member 55 Heat source

Claims (5)

The first member and
The second member and
The airgel film formed between the first member and the second member is included.
The first member and the second member are a first glass plate and a second glass plate, respectively.
A heat insulating window in which the airgel film is directly formed on the first member or the second member without gaps. A plurality of space over support in contact with said second member and said first member,
The airgel film of claim 1, wherein the heat insulating windows meet without gaps between the plurality of spacers. The heat insulating window according to claim 1 or 2 , wherein the airgel membrane is not a complex of airgel particles. The heat insulating window according to claim 1 or 2 , wherein the airgel membrane is a porous body containing airgel. The process of applying sol on the first glass plate and
The step of gelling the sol into a gel and
The step of hydrophobizing the gel and
The step of drying the gel to form an airgel film and
The process of placing the second glass plate on the airgel film and
Including
A method for manufacturing a heat insulating window in which the airgel film is directly formed on the first glass plate without gaps.

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