JPH01153896A - Heat-insulating board - Google Patents

Abstract

PURPOSE: To raise thermal insulation and mechanical strength by filling condensation-preventive processed super fine granules in the spaces of a honeycomb structure. CONSTITUTION: A thermal insulation board is formed by filling super fine granules, or a filling 3 of super fine granules mixed with fine granules of large diameters in the spaces 1a of the honeycomb structure 1, and fixing plates 2 on both sides of the structure by adhesive layers 4. The super fine granules are excellent for obtaining extremely narrow spaces, however as the super fine granules have condensation properties, the surfaces thereof are condensation- preventive processed so as to prevent condensation. Therefore, it is possible to keep the narrow spaces between the super fine granules.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a heat insulating board with excellent heat insulating properties and mechanical strength.

[Background technology]

The thermal conductivity of conventional insulation materials is 0.03~O', 05k
The thermal conductivity of air is 0.02 at cal/mhr 'C.
~0.024 kcal/mhr 'C. Like rigid polyurethane foam, 0.015 kcal/
Insulating materials with a low thermal conductivity of mhr'c have also been developed, but in the case of polyurethane foam, the low thermal conductivity of Freon gas sealed in the voids (0,006~
0.01 kcal/mhr"c), and if Freon gas is replaced with air after long-term use, the heat insulation properties will also deteriorate, and after about a year, the temperature will be 0.01 kcal/mhr"c) In some cases, the thermal conductivity has increased to about 0.021 to 0.024 kcal/mhr"c.

Further, in the case of foamed polyurethane, since it is composed of organic substances, it cannot be used at temperatures above 100°C, and its uses are limited.

On the other hand, a porous body of calcium silicate is used as a nonflammable material with low thermal conductivity. O9l Torr or foamed crushed pearlite
A vacuum state of about rr (Japanese Patent Application Laid-Open No. 60-3347
9), but all of them require maintaining a vacuum state, which poses problems in terms of manufacturing costs and the like. Moreover, even when used as a heat insulating material, the shape and use are extremely limited due to the need to maintain a vacuum, and it has not been fully put to practical use.

As a heat insulating material whose thermal conductivity exceeds that of air even at normal pressure, there is a material made from aggregates of microporous silica (Japanese Patent Publication No. 51-4
However, the difference in thermal conductivity with air was extremely small, and the strength was not sufficient. Therefore, it has not yet been fully utilized practically.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and aims to provide a practical heat insulating board that has excellent heat insulating properties at normal pressure and sufficient mechanical strength.

[Disclosure of the invention]

In order to obtain one of the above objects that has excellent heat insulation properties at normal pressure, the inventors first devised an invention in which the surface of ultrafine particles is treated to prevent agglomeration beforehand and then molded to obtain a microporous body. However, although the microporous material according to the previous invention had excellent heat insulation properties, the strength was not improved, and it was still very brittle and easily broken, just like the conventional material. It was difficult to handle.

Therefore, as a result of further investigation, it was discovered that these ultrafine particles could be filled into a honeycomb structure, and the present invention was completed.

That is, the present invention provides a heat insulating board in which the space of a honeycomb structure is filled with ultrafine particles, and the surface of the ultrafine particles is treated to prevent agglomeration. This is the summary.

Hereinafter, the microporous body according to the present invention will be explained in more detail.

First, the reason why the heat insulating board according to the present invention has excellent heat insulating properties at normal pressure will be explained.

The thermal conductivity of a porous material depends on the thermal conductivity of the gas (usually air) contained in the voids, so in order to eliminate the influence of the thermal conductivity of the gas, it is necessary to make the voids extremely narrow (the average of the gas The gap is smaller than the free path, and specifically, in the case of air, it needs to be, for example, about 1 nm to 60 nm). However, in a microporous material, as shown in Figure 4, even if the particles P are packed in a close-packed state, there are
Voids of about 15% of the particle size are created. Therefore, in order to obtain extremely narrow voids as described above, it was thought that a microporous material using particles with extremely small diameters, so-called "ultrafine particles", would be sufficient. However, ultrafine particles have agglomeration properties, and as shown in Figure 5, large multidimensional particles P
' is formed, and large voids are created between these multi-dimensional particles P'.
Strongly affected by the thermal conductivity of gas. For example, in the case of ultrafine silica particles, a large amount of OH of silanol groups is present on the particle surface, and since the bonds between the particles are strong due to hydrogen bonds, they are particularly prone to agglomeration. However, when the surface of the ultrafine particles of the microporous material of this invention is treated to prevent agglomeration, the gaps between the ultrafine particles A become extremely narrow, as shown in Figure 2. .

Therefore, the influence of the thermal conductivity of gas can be removed, and sufficient heat insulation properties can be obtained.

Since the insulation board has a structure in which ultrafine particles are filled as a filler within the honeycomb structure, the mechanical strength of the heat insulation board is significantly improved compared to a board made of only ultrafine particles. This makes insulation boards highly practical.

Next, the agglomeration prevention treatment applied to the surface of the ultrafine particles will be explained.

The aggregation prevention treatment is performed, for example, by adding a surface treatment agent to the ultrafine particles. Ultrafine particles include ultrafine silica produced by a dry or wet process (particle size: 1 rH11
-20 nm is preferable, and about 3-8 nm is more preferable). What is a surface treatment agent?
These include those that bind to OH groups on the particle surface to prevent the formation of hydrogen bonds, and those that provide repulsion between particles and directly prevent particle aggregation. Examples include alkoxysilane compounds such as trimethylmethoxysilane, dimethyljethoxysilane, dimethyldimethoxysilane, and methyltrimethoxysilane, chlorosilane compounds such as dimethyldichlorosilane, trimethylchlorosilane, and methylvinyldichlorosilane, and hexamethyldisilazane. , dimethyltrimethylsilylamine and other silazane compounds, but any silane compound that reacts with the surface of ultrafine particles may be used. The reaction may be either a gas phase reaction or a liquid phase reaction.

Note that when a solvent is used for the treatment with the surface treatment agent, examples of the solvent include benzene, water, toluene, and the like. Any solvent in which the ultrafine particles can be easily dispersed may be used.

Ultrafine silica particles tend to adsorb water molecules in the air and tend to change over time. However, when ultrafine silica particles are treated with the silane compound to prevent agglomeration, the ultrafine silica also has water repellency, hardly adsorbs water in the air, and prevents changes in heat insulating properties over time.

Next, one embodiment will be described in more detail with reference to the accompanying drawings.

As shown in FIGS. 1(a) and 1(b), in the heat insulation board according to this embodiment, the filling 3 containing ultrafine particles or fine particles with a large particle size coexists in the space of the honeycomb structure 1. The plate material 2 is filled in the portion 1a, and the plate material 2 is fixed to both sides or one side (both sides in the figure) with an adhesive layer 4.

It should be noted that the term "particles" used herein refers to particles having a shape such as a sphere, cube, or polyhedron with substantially equal dimensions in each direction, and does not include so-called fibrous particles having an extremely large dimension in one direction.

In addition to the ultrafine particles, as shown in FIG. 3, fine particles B having a larger particle size than the ultrafine particles A may coexist. In this case, since the ultrafine particles A are filled in the large gaps between the particles B having a large particle size, the size of the gap is the gap between the ultrafine particles A and A. Therefore, it is possible to form fine voids that are not affected by the thermal conductivity of still air. Moreover, if fine particles B are included,
It does not require large amounts of expensive ultrafine particles such as ultrafine silica, making it cheaper. Further, the inclusion of fine particles B has the advantage that moldability is improved.

This is thought to be because the large particles B and the ultrafine particles A have the function of keeping the molding pressure uniform by distributing and absorbing the molding pressure with each other.

Examples of the fine particles B include perlite, shirasu balloons, crushed products thereof, soot, dried colloidal sol, dry or wet process fine particle silica, diatomaceous earth, calcium silicate, and the like. Although it is not necessary to subject the fine particles B to anti-aggregation treatment, it goes without saying that such treatment may be carried out. Fine particles B are 5 nm = 1
More preferably, it is approximately 0,000 nm (rain particles A and B are selected so that the relationship between the particle size of ultrafine particles A and the particle size of fine particles B always holds).

The honeycomb structure l is made of a plate material such as kraft paper, asbestos paper, non-combustible honeycomb impregnated with aluminum hydroxide, ceramic, thin metal plate, etc., and has holes of any shape such as circular, triangular, square, hexagonal, etc. A conventional one formed into a structure can be used.

As mentioned above, the plate material 2 is fixed to both sides or one side of the honeycomb structure 1, and is made of paper such as kraft paper, asbestos paper, corrugated paper, or noncombustible paper impregnated with aluminum hydroxide. , metal plate, plywood, glass cloth,
Calcium silicate board, gypsum board, etc. are used.

To fix the plate material 2 to the honeycomb structure 1, for example, ■ an organic film such as nylon, polyethylene, etc. that softens at about 200°C and has adhesive properties, ■ epoxy resin, polyurethane resin, phenol resin, PVA, vinyl acetate, etc. Organic adhesives such as resins, acrylic resins, isocyanate resins, butadiene acrylonitrile resins, polysulfide rubber, ■ Inorganic adhesives such as water glass adhesives, colloidal inorganic binders, metal alkoxide hydrolysates, and liquefied borax. An adhesive layer 4 consisting of adhesive, etc. is used.

The honeycomb structure 1 and the plate materials 2 described above can be used in appropriate combinations depending on the purpose.

For example, when the insulation board of the present invention is used to insulate a high-temperature part, asbestos paper, non-combustible honeycomb, ceramic, thin metal plate, etc. are used as the honeycomb structure 1, and asbestos paper, Noncombustible paper, glass cloth, calcium silicate board, gypsum board, metal plate, etc. may be used. The adhesive layer 4 should also be selected to be suitable for adhering these materials.

Furthermore, when considering the heat insulation properties of the entire board, it goes without saying that it is preferable to use materials with low thermal conductivity for the honeycomb structure 1, the plate material 2, and the adhesive layer 4.

Next, specific examples and comparative examples of the present invention will be described, including manufacturing.

(Example 1) First, ultrafine particles subjected to agglomeration prevention treatment were prepared as follows. Dry process ultrafine particle silica (AEROSIL 380, manufactured by Nippon Aerosil 0 Kiku, particle size: approximately 7 nm) is stirred and dispersed in benzene, and hexamethyldisilazane (manufactured by Toshiba Silicone, TSL 8802) is added to this dispersion solution.
) was added, and after mixing for 30 minutes, stirring was continued for about 2 hours at the benzene reflux temperature (80° C.) to carry out the reaction. The weight ratio at this time was ultrafine silica:hexamethyldisilazane:benzene=1:0.13:18. This reaction solution was dried under reduced pressure at room temperature to obtain ultrafine particles treated to prevent agglomeration.

A paper honeycomb (38-3-0 manufactured by Showa Aircraft Industry Co., Ltd.) was prepared as the honeycomb structure 1, and this honeycomb structure 1
is installed in the mold, and the space 1 of the honeycomb structure 1 is
A was filled with ultrafine particles. After filling, the mixture was press-molded to obtain a molded article in which the voids 1a were filled with ultrafine particles. The molded body is taken out from the mold, and an organic film (Diamid Film 3102 manufactured by Daicel Chemical Industries, Ltd.) is placed on both sides of the molded body as an adhesive layer.
In this way, the board material 2 made of kraft paper was fixed to complete the insulation board. For fixation, soften the film by heating to 170°C and apply a pressure of 5 kg/co! This was done by pressure bonding.

(Example 2) As ultrafine particle silica produced by dry process, manufactured by Tokuyama Soda ■,
Except that REOLO5IL (particle size: about 5 nm) was used and the weight ratio during the reaction was ultrafine silica: hexamethyldisilazane: benzene = 1:0.16:27.
A heat insulating board was obtained in the same manner as in Example 1.

(Example 3) Silicone resin fine powder (manufactured by Toshiba Silicone@1, XC99-702 particle size:
A heat insulating board was obtained in the same manner as in Example 1, except that a material with a thickness of about 8 nm) was used.

(Example 4) As the honeycomb structure 1, asbestos honeycomb (Showa Aircraft Industry @ M 25-A-0) was used, asbestos paper (manufactured by Olivest Co., Ltd.) was used as the plate material 2, and water glass adhesive was used for the adhesive layer 4. 200℃, pressure 5K
A heat insulating board was obtained in the same manner as in Example 1, except that it was fixed for 2 hours at 1 g/cffl.

(Example 5) In the same manner as in Example 1, except that the ultrafine particles were mixed with particles obtained by grinding perlite (Perlite Type 1 FB manufactured by Ube Industries ■) in a ball mill for 24 hours, Got the insulation board.

(Comparative Example 1) Example 1 except that the surface of the ultrafine particles was not treated to prevent agglomeration.
A heat insulating board was obtained in the same manner as above.

(Comparative Example 2) The anti-aggregation treated ultrafine particles obtained in Example 1 were directly pressure-molded at a pressure of 10 kg/c+d to obtain a heat insulating board.

The thermal conductivity and bending strength of each heat insulating board of Examples and Comparative Examples were measured. Thermal conductivity was measured using a steady-state method thermal conductivity measuring device manufactured by Hideko Seiki.
- Set temperature 20°C and 40°C in accordance with C518
It was conducted under the following conditions. In addition, the bending strength is JIS A9510
Measured according to.

From the results in Table 1, it can be seen that all of the examples of the heat insulating boards of the present invention have significantly high strength while maintaining low thermal conductivity, and are more practical.

〔Effect of the invention〕

The heat insulating board of the present invention is as described in detail above, and since the space of the honeycomb structure is filled with ultrafine particles treated to prevent agglomeration, it has excellent heat insulating properties. Furthermore, it has mechanical strength that can withstand practical use.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the internal structure of an embodiment of the heat insulating board of the present invention.
Figure (b) is a sectional view taken along the line X-x in figure (a), Figure 2 is an explanatory diagram illustrating an example of the filling state of ultrafine particles filled in the space of the honeycomb structure, and Figure 3 is An explanatory diagram illustrating another example of the filling state of ultrafine particles filled in the spaces of the honeycomb structure, FIG. 4 is an explanatory diagram illustrating an example of the state of voids between the microparticles, and FIG. It is an explanatory view explaining a reference example of the gap state between. 1...Honeycomb structure 1a...Space part A...
Ultrafine particles B...Fine particle agent Patent attorney Takeshi Matsumoto Sky tube 1 Figure (a) ・ :? 41j Figure 2 Cause 3 Figure 4 Figure 5

Claims (4)

[Claims] (1) A heat insulating board in which the space of a honeycomb structure is filled with ultrafine particles, the surface of the ultrafine particles being treated to prevent agglomeration. (2) The size of the void formed between the filled particles is 1
The heat insulating board according to claim 1, which has a thickness of 60 nm to 60 nm. (3) The heat insulating board according to claim 1 or 2, wherein the agglomeration prevention treatment is performed using a silane compound. (4) The insulation board according to any one of claims 1 to 3, wherein the space is also filled with fine particles having a larger diameter than the ultrafine particles.