JP2017105948A - Insulation and manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat insulating material having high heat insulating property and high strength and a method for producing the same. A step of blending with a monomer liquid of the first resin composition having a difference of more than 3 (cal / cm3) 1/2, dispersing and curing to prepare a cured resin product in which xerogel beads are dispersed, and the first resin curing. The difference in solubility parameter between the step of crushing the material and producing a composite heat insulating filler containing at least one xerogel beads in the crushed material piece and the solubility parameter of the composite heat insulating filler with the first resin composition is 5 A step of blending with a monomer liquid of a second resin composition smaller than (cal / cm3) 1/2, dispersing and curing, and a method of producing a heat insulating material containing the same are used. [Selection diagram] Fig. 2

Description

The present invention relates to a heat insulating material and a manufacturing method thereof. In particular, it is related with the heat insulating material containing a silica xerogel or a silica airgel, and its manufacturing method.

  The bead-like silica xerogel or silica aerogel has a small thermal conductivity because it contains many voids of several nm in its structure, and is suitable as a heat insulating material.

  Moreover, the material which disperse | distributed and mixed not only these but the heat insulating filler in the other binder exhibits the performance outstanding as a heat insulating material (patent document 1).

  Aerogel refers to a gel dried using supercritical drying, and xerogel refers to a gel dried at normal pressure without using supercritical drying. If the airgel and xerogel have the same structural properties such as the pore diameter and pore volume of the gel, the heat insulating performance is basically the same.

  Unless otherwise specified, the term xerogel herein includes aerogels, xerogels or mixtures thereof.

  However, in such a silica xerogel, nanometer-sized silica primary particles form a gel skeleton. For this reason, silica xerogel is fragile and easily broken.

  Therefore, these silica xerogel beads are mixed with a binder material.

JP 2002-179846 A

  However, in the process of kneading the silica xerogel beads to the base material serving as the binder, external force such as shear is applied to the beads, so that it often becomes difficult to maintain the heat insulating property by being broken.

  Further, both the bead surface and the porous portion of these xerogel beads are often lipophilic. In this case, the lipophilic binder substrate enters the bead surface of the xerogel beads, and the air layer is removed from the porous portion. This impairs the heat insulation properties.

  Therefore, the problem of the present invention is that the heat insulating filler such as silica xerogel contained in the resin binder is not destroyed, and the resin binder does not penetrate into the porous structure of the filler, and excellent heat insulating properties are maintained. It is providing a heat insulating material and its manufacturing method.

  In order to solve the above problems, a heat insulating material comprising a bead-like heat insulating material, a first resin material containing the bead-like heat insulating material, and a second resin material containing the first resin material. Use materials.

Also, a resin composition in which the difference in solubility parameter between the step of hydrophilizing xerogel beads by surface treatment and the hydrophilized xerogel beads is greater than 3 (cal / cm ³ ) ^1/2 And a step of preparing a resin cured product in which xerogel beads are dispersed by mixing and dispersing in the monomer liquid, and crushing the resin cured product, and at least one xerogel bead is contained in a pulverized product piece. The monomer liquid of the second resin composition in which the difference in solubility parameter between the step of producing the composite heat insulating filler and the composite heat insulating filler is less than 5 (cal / cm ³ ) ^1/2 of the first resin composition. And a step of blending, dispersing and curing, and a method for producing a heat insulating material.

  In the heat insulating material of the present invention, the xerogel beads, which are heat insulating fillers, are subjected to a hydrophilic treatment, thereby forming a composite heat insulating filler in which the first resin is prevented from entering the porous body.

  For this reason, the first resin mechanically protects the heat-insulating filler, and when it is dispersed and blended in the second resin, even if it is subjected to a homogenization treatment by applying shear or the like, the silica xerogel beads Becomes an excellent heat insulating material without being crushed.

The figure which shows the manufacturing process of embodiment Sectional drawing which shows the heat insulating material of (a)-(e) embodiment The figure showing the decomposition reaction of the hydrophobic group of the xerogel bead surface in embodiment The figure which shows the thermogravimetric change of the xerogel bead of embodiment (A) Photograph of a state in which xerogel beads not subjected to surface treatment in a comparative example are put into water, (b) Photograph of a state in which xerogel beads subjected to hydrophilization treatment in examples are put into water (A) to (c) As a comparative example, a micrograph when xerogel beads are added to the liquid, and (d) to (e) as microscopic examples when xerogel beads are added to the liquid as examples. (A)-(b) In embodiment, the resin cured material which mix | blended the xerogel bead and the enlarged micrograph of the one part (A) As a comparative example, a photograph when a resin piece of dimethylpolysiloxane is added to a liquid, and (b) to (f) Photographs when a resin piece of dimethylpolysiloxane is added to a liquid as an example. (A)-(b) As a comparative example, when xerogel beads are blended with the first resin without heat treatment, and a part of the enlarged photograph

Hereinafter, embodiments of the present invention will be described in detail.
(Embodiment)
The manufacturing method of the heat insulating material of this Embodiment is as follows. That is, as shown in FIG. 1, first, a xerogel using a high molar silicic acid solution as a raw material is prepared. This is pulverized to form beads (particulate), the beads are hydrophilized by a process such as baking at a high temperature, and the hydrophilized beads are dispersed in the first resin composition.

  Next, the first resin composition in which the beads are dispersed and blended is crushed to obtain a new composite heat insulating filler in which at least one bead is contained in the crushed resin piece. It is a manufacturing method which makes it a heat insulating material by dispersing and blending in a resin composition.

  The heat insulating material 25 of embodiment is shown to Fig.2 (a)-FIG.2 (e). The heat insulating material 25 of the embodiment is such that a heat insulating material 30 such as xerogel is covered with a first resin 31 (resin composition) and the periphery thereof is covered with a second resin 32 (resin composition). is there.

  Here, the heat insulating material 30 does not need to be completely covered with the first resin 31, and a part of the heat insulating material 30 may protrude from the first resin 31. Since the shape of the 1st resin 31 is crushed as shown above, it is square. However, the first resin 31 may be rounded. It is preferable that the first resin 31 is square because it is easily covered with the second resin 32. In addition, in FIG. 2 (a)-FIG.2 (e), although the heat insulating material 25 is drawn granularly, it is used with required forms, such as a rectangular parallelepiped.

  The production method will be described below. In addition, although the example using the bead of a xerogel is demonstrated as an example as the heat insulation material 30, another heat insulation material can also be used.

  (1) Preparation of high molar silicic acid solution, (2) Production of xerogel beads, (3) Hydrophilization treatment of xerogel beads, (4) Formulation of hydrophilized xerogel beads into resin composition, (5) Contains xerogel beads Manufacturing the heat insulating filler by pulverizing the first resin 31, and (6) blending the heat insulating filler into the second resin 32. Details of each are described below.

(1) Preparation of high molar silicic acid solution High molar silicic acid aqueous solution is manufactured from water glass called sodium silicate aqueous solution or sodium silicate aqueous solution. As a composition, the molecular formula of water glass is represented by Na ₂ O · nSiO ₂ · mH ₂ O, whereas H ₂ O has various SiO ₂ (anhydrous silicic acid) and Na ₂ O (sodium oxide). Expressed as a liquid dissolved in proportions.

Here, n is a molar ratio representing a mixing ratio of Na ₂ O and SiO ₂ . That is, the high molar silicic acid aqueous solution is a raw material stabilized on the basic side after removing sodium unnecessary for the construction of the xerogel from the water glass, and is not water glass nor colloidal silica. A feature of the high molar silicic acid aqueous solution is that the particle size of the sol is in an intermediate size (1 to 10 nm) between water glass and colloidal silica.

(2) Production of Xerogel Beads (Insulating Material 30) The above high molar silicic acid solution is gelled by adjusting pH by adding hydrochloric acid or the like, and the gel is cured. Next, the cured gel is immersed in a mixed solution of hexamethyldisiloxane, isopropyl alcohol, and hydrochloric acid, for example, to replace the silanol group present in the system with the trimethylsilyl group, and to make the gel finally hydrophobic. Silica xerogel can be obtained by spring back.

As the characteristics of the produced xerogel, the average pore diameter, pore volume, specific surface area and the like can be measured by a nitrogen adsorption method. For example, the average pore diameter is 10 to 60 nm, the pore volume is 3.0 to 10 cc / g, and the specific surface area is 200 to 500 m ² / g.

  Next, a xerogel bead can be obtained by pulverizing the xerogel prepared as described above. The gel can be pulverized by combining a pulverizer such as a jet mill and a mesh, and xerogel beads having a particle diameter of about 20 μm to about 2 mm can be obtained.

(3) Hydrophilization treatment of xerogel beads Next, the xerogel beads are blended, dispersed, and cured in the monomer liquid of the resin composition or a molten liquid resin heated above the softening point. However, the xerogel beads prepared as described above are hydrophobic due to the influence of the hydrophobizing treatment such as trimethylsilyl group and the like, up to the inner wall of the nanoporous surface and the inside. For this reason, if this is blended with a monomer liquid of a hydrophobic resin composition or a molten liquid resin heated to a temperature higher than the softening point, the monomer liquid enters the bead surface and nanoporous, and the heat insulation is impaired.

  Therefore, by making the xerogel beads hydrophilic by surface treatment, the infiltration of the monomer liquid or molten liquid resin into the nanoporous xerogel beads is suppressed.

<Surface treatment>
The surface treatment method of the xerogel beads can be specifically performed by heat treatment. On the surface of the xerogel beads, silanol groups remaining after completion of the curing are replaced with hydrophobic groups in the hydrophobizing step. When heated at a temperature equal to or higher than the thermal decomposition temperature of the hydrophobic group, as shown in FIG. 3, the hydrophobic group is dissociated from the siloxane skeleton by hydrolysis or oxidation reaction, and the hydrophobicity of the surface and nanoporous inner wall is lost.

  In this embodiment, the hydrophobic group is a trimethylsilyl group derived from a decomposition product of HMDSO. FIG. 4 shows a thermogravimetric analysis of the xerogel beads. FIG. 4 shows that the decomposition temperature is about 400.degree.

  Therefore, in an electric heating furnace, 1.5 g of xerogel beads were placed in a stainless steel container and heated at 450 ° C. for 12 hours. FIGS. 5 (a) and 5 (b) show the appearances of water heated for 12 hours and those not heat-treated in water, respectively.

  As shown to Fig.5 (a), what is not heat-processed (comparative example) does not sink in water since it is hydrophobic. On the other hand, it can confirm that what hydrophilized by heat processing (450 degreeC, 12 hours) (Example) is hydrophilized by sinking in water as shown in FIG.5 (b). It was.

(4) Formulation and Crushing of Hydrophilized Xerogel Beads into Composition of First Resin 31 The surface-treated xerogel beads are blended and dispersed in the liquid resin as the first resin 31 to cure the liquid resin. When the liquid resin is a monomer liquid, a curing method such as thermal curing or photocuring may be selected according to an optimal curing method for the monomer. Further, when the liquid resin is a molten liquid resin heated to the softening point or higher, the xerogel beads may be cooled to the softening point or lower after dispersion.

<Solubility parameter of first resin 31>
Hereinafter, the monomer liquid which is the first resin 31 and the molten resin heated to the softening point or higher are collectively referred to as a liquid resin. In order to insert the xerogel beads into the first resin 31, it is important that the solubility parameter of the surface of the xerogel beads after the surface treatment is sufficiently separated from the solubility parameter of the liquid resin. Since the difference in solubility parameter is preferably as large as possible, the upper limit is not particularly set.

  The solubility parameter is a parameter that represents a measure of the affinity between substances, and materials having similar solubility parameters are likely to be mixed and easily wet between a solid and a liquid.

  FIGS. 6A to 6E show photographs when the xerogel beads after heat treatment are added to liquids having different solubility parameters. Table 1 shows the liquid types and solubility parameters in each figure.

The xerogel beads after the heat treatment are considered to have hydroxyl groups decomposed to become hydroxyl groups. For this reason, the solubility parameter is close to methanol and ethanol, and is considered to be about 13 (cal / cm ³ ) ^1/2 .

  As can be seen from the results of FIGS. 6A to 6E, the xerogel beads in the liquid are almost transparent up to methanol, ethanol, and isopropyl alcohol, and this is the result of the liquid entering the xerogel beads. . 6A to 6C are Comparative Examples 1 to 3. FIG. FIG. 6D and FIG. 6E are Examples 1 and 2.

However, in liquid epoxy (FIG. 6 (d)) and decamethyltetrasiloxane (FIG. 6 (e)) in which the difference in solubility parameter is 3 (cal / cm ³ ) ^1/2 or more, the xerogel beads are not transparent. It can be seen that no liquid has entered the interior.

Based on the above results, in order to suppress the penetration of the liquid resin into the xerogel beads, the difference between the solubility parameter of the xerogel beads surface and the solubility parameter of the liquid resin is 3 (cal / cm ³ ) ^1/2 or more. It is desirable. When xerogel is hydrophobized by a trimethylsilyl group, its solubility parameter is estimated to be about 7.5 (cal / cm ³ ) ^1/2 that is close to that of silicone rubber.

It is not good when the difference between the solubility parameter of the xerogel beads surface and the solubility parameter of the liquid resin is 3 (cal / cm ³ ) ^1/2 or less. That is, it is the case of many general-purpose resins and rubbers having an SP value in the range of 4.5 to 10.5 (cal / cm ³ ) ^1/2 . Examples thereof include polypropylene, polyethylene, polyvinyl chloride, fluorine resin, silicone resin, polyisobutylene, polybutadiene, polyvinyl acetate, polymethyl methacrylate, acrylic rubber, urethane rubber, and epoxy resin. In these cases, wettability is good with the xerogel beads not subjected to surface treatment as described later, and the liquid monomer penetrates into the porous structure due to the wettability of the surface of the xerogel beads and the liquid monomer, and the heat insulation performance is impaired. Become.

For example, since the solubility parameter of the silicone-based resin composition monomer described later is 7.5 (cal / cm ³ ) ^1/2 , the monomer liquid penetrates into the porous structure of the xerogel beads when mixed. For example, the solubility parameter can be reduced to about 12 to 14 (cal / cm ³ ) ^1/2 by a surface treatment described later. As a result, from the viewpoint that the difference in solubility parameter with a resin having a solubility parameter in the range of 4.5 to 10.5 can be larger than 3 (cal / cm ³ ) ^1/2 , many resins including silicone resins are used. The penetration of the liquid resin into the porous structure can be suppressed.

  In addition, the solubility parameter of liquid resin can be estimated from those chemical structures by an atomic group contribution method, and can also be obtained from literature values.

  Similarly, the solubility parameter of the xerogel beads can be estimated from the structure of the treatment agent coated to make the surface hydrophobic.

<Type of first resin 31>
As the first resin 31, the liquid resin that is the first resin 31 needs to be hydrophobic so that the resin monomer liquid does not enter the porous structure. Since the solubility parameter on the surface of the xerogel beads after hydrophilization is about 13 (cal / cm ³ ) ^1/2 , polypropylene, polyethylene, polychlorinated, whose solubility parameter is 10 (cal / cm ³ ) ^1/2 or less Vinyl, fluororesin, silicone resin, polyisobutylene, polybutadiene, polyvinyl acetate, polymethyl methacrylate, acrylic rubber, urethane rubber, epoxy resin, and mixtures thereof can be used.

  Here, as the first resin 31, a two-component mixed addition reaction type dimethyl silicone monomer liquid was used. The first resin 31 after curing is dimethyl silicone. The main chain structure is a siloxane skeleton structure, and a methyl group is bonded to a silicon atom. Furthermore, a reactive site necessary for bonding of siloxane skeletons such as a vinyl group is bonded to the terminal of the siloxane skeleton. When the siloxane skeleton is thermally cured, a hydrosilylation reaction occurs, and a cured product is formed in a shape containing dispersed xerogel beads therein.

In addition, the functional group bonded to the silicon atom can be represented by a general formula C _n H _{2n + 1-2k-2l-4m} including a methyl group from the viewpoint that the first resin 31 needs to be hydrophobic. A hydrogen group is desirable.

  Here, n is the number of carbon atoms in the functional group, and k, l, and m are the number of double bonds, the number of rings, and the number of triple bonds in the functional group, respectively.

<Concentration>
The addition amount of the xerogel beads to the liquid resin that is the first resin 31 is preferably such that the volume ratio of the xerogel beads in the mixture of the liquid resin and the xerogel beads is 12% by volume or more and 80% by volume or less. If the volume ratio is less than 12%, the amount of xerogel beads in the resin becomes too small, and the xerogel beads contained in the crushed pieces after the first resin 31 to be described later are reduced, thereby ensuring sufficient heat insulation. It is not preferable because it cannot be performed. On the other hand, if it is larger than 80% by volume, the air contained in the cured resin becomes too much due to aggregation of the xerogel beads, so that it cannot be formed into a molded body, and is not covered with the first resin 31 composition. The xerogel beads appear and are not preferable. In the present embodiment, the volume is 45% by volume. When the specific gravity of the monomer liquid is 0.97 and the bulk density of the xerogel beads is 0.07, the weight ratio is about 0.8 wt% or more and about 23.1 wt% or less. In the present embodiment, 33 g of resin monomer mixed in two liquids and 3 g of hydrogelated xerogel beads were mixed in a beaker.

<Distribution method>
Although it does not limit as a dispersion method, it stirred with the glass rod. When stirring with a glass rod, stirring was performed while considering that the xerogel beads were not broken by shearing between the glass rod body and the inner wall of the beaker. In addition, a known method can be used for dispersion, such as stirring while agitating blades are driven by a motor. After stirring, the liquid monomer of the first resin 31 composition in which the xerogel beads were dispersed was heated at 60 ° C. for 4 hours to be cured. The curing conditions may be matched to the curing conditions of each liquid resin. When a molten resin having a temperature higher than the softening point is used, the resin can be cured by solidification by cooling to a melting temperature or lower.

At this time, the solubility parameter of the cured resin composition was estimated to be about 7.5 (cal / cm ³ ) ^1/2, which is a generally known solubility parameter of the silicone resin, and the surface treatment described above was performed. The difference in solubility parameter of the silica xerogel beads is 3 (cal / cm ³ ) ^1/2 or more.

<Product>
Examples of the resin containing the cured xerogel beads produced in this way are shown in FIGS. 7 (a) and 7 (b). FIG. 7A is an overall photograph, and FIG. 7B is an enlarged photograph of a part thereof.

  In FIG. 7 (b), the xerogel beads 10 in which air remains contained in the porous structure are dispersed in the cured resin 11 by the hydrophilization treatment. Since it is low, the air layer 12 is formed on at least a part of the surface. Xerogel beads may be aggregated.

<Crushing>
Next, the cured product of the first resin 31 containing xerogel beads is pulverized to an appropriate size, and a composite heat insulating filler in which at least one xerogel bead is contained in each piece after pulverization is obtained. it can.

  The particle size of the composite heat insulating filler after pulverization is not limited, but can be 250 μm or more and 5 mm or less. The pulverizer and the pulverization method can be performed by known methods. The pulverizer is not limited and, for example, a general high-speed rotary pulverizer can be used. In this pulverization process, the silica xerogel beads are pulverized into individual pieces each embedded with a small number of beads, and the resin composition does not enter the porous part of the beads, and the composite has excellent heat insulation properties. It can be set as a heat-insulating filler. In addition, when the elastic modulus of the first resin 31 composition is small and pulverization by a pulverizer is difficult, it may be pulverized manually by an operator using a mortar. In this embodiment, pulverization is performed by a mortar. Yes.

(5) Blending of composite heat insulating filler into resin composition By blending the composite heat insulating filler produced by the above process and containing at least one xerogel bead into the second resin 32, heat insulation and A composite material having excellent strength can be obtained.

<Mixing method>
For example, the liquid resin that is the second resin 32 is stirred in a container. The composite heat insulating filler can be charged and dispersed therein, and then poured into a mold and cured to obtain a composite material.

  In this case, the xerogel beads are protected by being embedded in the first resin 31. Therefore, when the xerogel beads are blended and dispersed in the second resin 32, an operation such as applying a shearing stress that is difficult with the xerogel beads alone can be performed.

  Therefore, the xerogel beads are uniformly dispersed in the second resin 32 without containing voids. As a result, the composite material has excellent heat insulation and high strength.

<Second resin 32>
The second resin 32 may be the same as or different from the first resin 31 of the present embodiment, but from the viewpoint of improving the dispersibility and maintaining the strength of the final heat insulating material 25, The solubility parameter of the first resin 31 and the solubility parameter of the second resin 32 are preferably close. The difference can be at least 7 (cal / cm ³ ) ^1/2 or less. This can be confirmed by the following experimental results.

<Type>
When adding a polydimethylsiloxane resin piece (hereinafter, resin piece 19) having a solubility parameter of 7.5 (cal / cm ³ ) ^1/2 to FIGS. 8A to 8F to liquids having different solubility parameters. The photograph of is shown. The types of liquids and solubility parameters in each figure are as shown in Table 2. FIG. 8A shows Comparative Example 4, and FIGS. 8B to 8F show Examples 3-7.

As can be seen from FIGS. 8B to 8F, in methanol, ethanol, isopropyl alcohol, bisphenol A liquid epoxy, decamethyltetrasiloxane, the resin pieces 19 are dispersed in the liquid, and the aggregate 20 is I can't watch it. The bisphenol A type liquid epoxy floats due to its large specific gravity, but does not aggregate 20. In other words, in a liquid having a solubility parameter difference of 7.2 (cal / cm ³ ) ^1/2 with the resin piece 19 having a solubility parameter of 7.5 (cal / cm ³ ) ^1/2 , the resin piece 19 is It can be said that there is no problem.

However, in the case of water in which the difference in solubility parameter from the resin piece 19 is 15 (cal / cm ³ ) ^1/2 or more, as shown in FIG. 8A, aggregation 20 is observed and dispersion does not proceed. I understand that.

From the above, when the difference in solubility parameter is at least smaller than 7.2 (cal / cm ³ ) ^1/2 , dispersion proceeds, and when the difference in solubility parameter is greater than 7.2, combined insulation There is a possibility that the compatibility between the filler and the second resin 32 is deteriorated, the composite heat insulating filler is agglomerated, and voids are generated between the composite heat insulating fillers, resulting in a decrease in strength of the final composite material. . The closer the solubility parameter, the higher the compatibility and the better, so there is no lower limit.

In the present embodiment, the same silicone resin monomer as the first resin 31 is used as the liquid resin.
<Amount of composite heat insulating filler added>
Although it does not limit as the addition amount of the composite heat insulation filler with respect to liquid resin (2nd resin 32), it can be 20 to 90 weight%. That is, when the filler addition amount to the first resin 31 is 0.8 wt% or more and 23.1 wt% or less as described above, the blending amount of the heat insulating filler in the final composite material is 0.16 wt%. % To 20.8% by weight is preferable.

  That is, if the final addition amount is less than 0.16% by weight, sufficient heat insulation cannot be obtained, which is not preferable. If the amount exceeds 20.8% by weight, the amount of the composite heat insulating filler added to the liquid resin of the second resin 32 will exceed 23.1% by weight, exceeding 23.1% by weight. And, the viscosity of the liquid resin becomes too high, and it becomes difficult to mold into a desired form, which is not preferable.

In this embodiment, the addition amount of the composite heat insulating filler to the liquid resin of the second resin 32 is 50% by weight. Specifically, the second resin 32 may be the same as the first resin 31, and as described above, the difference from the solubility parameter of the first resin 31 is at least 7 (cal / cm ³ ) ^1/2. Choose as follows:

  In this embodiment, 25 g of a resin liquid monomer similar to the liquid monomer of the first resin 31 is prepared in a beaker, 20 g of a composite heat insulating filler is added thereto, and kneaded while applying shear to the inner wall of the spatula and the beaker, Dispersed. The dispersed sheet was sandwiched between two pieces of glass provided with an appropriate amount of spacer having a thickness of 2 mm, and heated at 60 ° C. for 4 hours to obtain a heat insulating sheet having a thickness of 2 mm.

<Example 8>
As Example 8, a composite heat insulating material 25 was manufactured according to the manufacturing process of the above embodiment.
That is, 7 g of 12N hydrochloric acid was added to 50 g of a high molar silicic acid solution having a concentration of 14% to adjust the pH to 7, thereby causing gelation.

  Next, the gelled one is sealed and cured in a thermostatic bath at 85 ° C. for 3 hours to further promote the gelation, and the gelation is promoted by adding 20 g of HMDSO and 20 g of isopropanol. Hydrophobization was performed by immersing in a mixed solution to which 45.2 g of hydrochloric acid was added for 12 hours.

  After completion of the hydrophobization, the mixture was dried by heating at 150 ° C. for 2 hours to prepare a xelgel, and the obtained xerogel was pulverized with a rotary pulverizer to prepare xerogel beads.

  The xerogel beads were treated at 450 ° C. for 12 hours, and 3 g of the treated xerogel beads were blended and dispersed in 33 g of a monomer liquid of a two-component mixed type addition silicone resin, and further heated at 60 ° C. for 4 hours to be cured.

  The obtained cured product was pulverized with a mortar to obtain a composite heat insulating filler in which at least one xerogel bead was contained in the resin piece of the first resin 31. In this way, 25 g of the composite heat insulating filler thus prepared was blended with 25 g of the monomer liquid of the two-component mixed type addition silicone resin similar to the first resin 31, kneaded, and cured between the glass plates provided with spacers. By doing so, the composite heat insulating filler 25 in which the composite heat insulating filler was dispersed in the second resin 32 was obtained.

<Comparative Example 5>
As Comparative Example 5, 2.27 g of xerogel beads heat-treated at 450 ° C. for 12 hours was directly blended with 47.73 g of the second resin 32, and the others were kneaded and sheeted in the same manner as in Example. Produced. The other conditions are the same as in Example 8.

  In the comparative example 5, it is set as the composite heat insulation filler, without mix | blending with the 1st resin 31 and hardening.

<Effect>
As a result of measuring the thermal conductivity of the heat insulating sheet in Example 8 and the sheet of Comparative Example 5, the thermal conductivity of Example 8 is 57.5 mW / mK, whereas it is 63 mW / mK in Comparative Example 5, The heat insulating sheet in Example 8 showed excellent heat insulating performance.

  The thermal conductivity was measured by a steady method using HFM436 manufactured by NETZSCH.

  In Comparative Example 5, the low-strength xerogel beads were directly blended with the resin monomer (second resin), and the kerogel beads were crushed during the kneading process, so that the porous structure could not be maintained and the thermal conductivity increased. I think that the.

  Moreover, as a result of measuring the tensile strength of the heat insulation sheet in Example 8 and the sheet of Comparative Example 5, the strength of Example 8 is 9.0 kN / m, whereas in Comparative Example 5, it is 6.7 kN / m. The heat insulating sheet in Example 8 showed excellent strength.

  The tensile test was conducted in accordance with JIS 6251 defined for the method of obtaining the tensile properties of rubber.

  In Comparative Example 5, it is explained that the strength is reduced because the air layer present at the interface between the xerogel beads and the resin composition becomes a starting point of cracking during tension. A comparison between Example 8 and Comparative Examples 5 and 6 is shown in Table 1.

  A pass / fail judgment was made with a thermal conductivity of 60 mW / mK or less as pass and a tensile strength of 8.0 kN / m or more as pass.

<Example 9>
Example 9 is different from Example 8 in that the first resin 31 and the second resin 32 are different, and the others are the same.

  3 g of hydrophilized xerogel beads surface-treated by the same method as in Example 8 were added to 33 g of the two-component mixed addition reaction type dimethyl silicone monomer as in Example 8, and stirred with a glass rod. did. When stirring with a glass rod, stirring was performed while considering that the xerogel beads were not broken by shearing between the glass rod main body and the inner wall of the beaker to obtain a dispersion. This dispersion was heated in a beaker at 60 ° C. for 4 hours to be cured. After curing, the cured product containing the xerogel beads was taken out from the beaker and pulverized at 1000 rpm with a continuous rotary mill to prepare a composite heat insulating filler.

  20 g of the composite heat insulating filler produced in this way was blended with 25 g of epoxy resin and cured and molded into a flat plate having a thickness of 2 mm. As the epoxy resin, a liquid obtained by mixing bisphenol A type liquid epoxy 23 and 2.3 g of diethylenetriamine was cured by leaving it at room temperature for 12 hours.

<Comparative Example 6>
As Comparative Example 6, xerogel beads were not heat-treated and not surface-treated. Used in the same manner as in Example 9, pulverized in silicone resin, and further pulverized product into similar epoxy resin. Blended to form a flat cured product.

At this time, photographs of those obtained by blending and curing xerogel beads that were not heat-treated and not surface-treated in the silicone resin are shown in FIGS. 9 (a) to 9 (b).
FIG. 9A is an overall photograph, and FIG. 9B is an enlarged photograph of a part thereof. As shown in FIG. 9B, the surface of the xerogel beads 10 remains hydrophobic and is highly compatible with the silicone resin that is the first resin 31. Therefore, it can be seen that the surface is well wetted with the resin, and bubbles as shown in the air layer 12 of FIG. 7 are not observed.

(effect)
As a result of measuring the thermal conductivity of the heat insulating sheet in Example 9 and the sheet of Comparative Example 6, the thermal conductivity of Example 9 was 55 mW / mK, while that of Comparative Example 6 was 77 mW / mK. The heat insulating performance of 9 heat insulating sheets was excellent. In Comparative Example 6, since the heat treatment of the xerogel beads was not performed, the liquid monomer of the resin entered the porous structure of the xerogel beads, and the heat insulation was impaired, so that the thermal conductivity was increased. Table 1 shows a comparison between Example 9 and Comparative Example 2.

  As the thermal conductivity, 60 mW / mK or less was regarded as acceptable. The tensile strength could not be measured because the cured epoxy resin was hard.

(Conclusion)
From the comparison between Example 8 and Comparative Example 5 shown in Table 1, the xerogel beads are protected by making the composite heat insulating filler once the surface-treated xerogel beads are contained in the first resin 31. It is clear that a typical heat insulating material 25 can be formed.

  Moreover, when the hydrophilization treatment (surface treatment) of xerogel is not performed by comparison between Example 9 and Comparative Example 6, it can be seen that an increase in thermal conductivity is observed and the heat insulation performance is inferior.

  As mentioned above, when manufacturing the heat insulating material 25 which mix | blended heat insulating fillers, such as a xerogel, the composite heat insulating filler which hydrophilized by heat processing etc. and protected the hydrophilized heat insulating filler with the 1st resin 31 piece, It turns out that it is effective.

  As described above, the heat insulating filler of the present embodiment and the heat insulating material using the heat insulating filler are widely used as excellent heat insulating materials.

DESCRIPTION OF SYMBOLS 10 Xerogel beads 11 Resin hardened | cured material 12 Air layer 19 Resin piece 20 Aggregation 23 Liquid epoxy 25 Thermal insulation material 30 Thermal insulation material 31 1st resin 32 2nd resin

Claims (7)

A first resin material including a bead-like heat insulating material;
And a second resin material containing the first resin material. The solubility parameter difference between the bead-like heat-insulating material and the first resin material is greater than 3 (cal / cm ³ ) ^1/2 ;
The heat insulating material according to claim 1, wherein a difference in solubility parameter between the first resin material and the second resin material is smaller than 7 (cal / cm ³ ) ^1/2 . The heat insulating material according to claim 1 or 2, wherein the bead-like heat insulating material is silica xerogel beads. The heat insulating material according to claim 1 or 3, wherein the first resin material and the second resin material are the same. The heat insulating material according to any one of claims 1 to 3, wherein the first resin material and the second resin material are different materials. A step of hydrophilizing the xerogel beads by surface treatment;
The hydrophilized xerogel beads are blended in the monomer liquid of the first resin composition having a solubility parameter difference from the xerogel beads of greater than 3 (cal / cm ³ ) ^1/2 , dispersed and cured, A step of producing a cured resin in which the xerogel beads are dispersed;
Crushing the first resin cured product, and producing a composite heat insulating filler containing at least one xerogel beads in a pulverized product piece;
The composite heat insulating filler is blended in a monomer liquid of a second resin composition having a solubility parameter difference from the first resin composition of less than 5 (cal / cm ³ ) ^1/2 , and is dispersed and cured. The process and the manufacturing method of the heat insulating material containing. The method for producing a heat insulating material according to claim 6, wherein the surface treatment of the xerogel beads is a method of performing a heat treatment at a temperature equal to or higher than a decomposition temperature of the surface hydrophobic group.

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