JP6960291B2 - Insulation - Google Patents

Description

The present invention relates to a heat insulating material, and more particularly to a heat insulating material made of a styrene-based resin foamed particle molded product and suitable for architectural use.

Conventionally, when manufacturing a heat insulating plate made of a foamed particle molded product, a foamed particle molded product that does not contain a radiant heat transfer inhibitor such as graphite or carbon black and a radiant heat transfer inhibitor such as graphite or carbon black are included. A composite molded body having a two-layer structure was manufactured by laminating the foamed particle molded body. However, when manufacturing a heat insulating material made of such a laminated body, a laminating step is required, so that a reduction in the number of laminating steps and a cost reduction have been required.

Further, in the case of a laminated body, there are problems that the physical properties tend to vary depending on the laminated surface, it is difficult to design a heat insulating layer, and it is difficult to design a free molded body shape.

Japanese Unexamined Patent Publication No. 2003-192821

The present invention has been made in view of the actual conditions of the prior art, has an appropriate density as a heat insulating material, has stable thermal conductivity, excellent heat insulating performance, and has a degree of freedom in the shape of the molded product. An object of the present invention is to provide a heat insulating material suitable for excellent building applications.

According to the present invention, in order to solve the above problems, first, the radiant heat transfer inhibitor is used as the styrene-based resin foamed particle molded body and the styrene-based resin foamed particles constituting the foamed particle molded body. The foamed particles A having a content of 1 to 10% by mass and the foamed particles B having a content of the radiant heat transfer inhibitor of less than 1% by mass (including 0) are contained in the thickness direction of the foamed particle molded body. The average value (S1 / S2) of the total area (S1) of the foamed particles A and the total area (S2) of the foamed particles B in the cross section perpendicular to is in the range of 0.1 to 4.0. , A heat insulating material having a fluctuation coefficient of the area ratio of 40% or less is provided.

Secondly, in the first invention, there is provided a heat insulating material in which the radiant heat transfer inhibitor is graphite.

Thirdly, in the first or second invention, there is provided a heat insulating material having a density of the styrene-based resin foamed particle molded product of 10 to 50 kg / m ^3.

Fourth, in any of the first to third aspects of the invention, there is provided a heat insulating material having a thermal conductivity of 0.037 W / m · K or less of the styrene-based resin foamed particle molded body.

Fifth, in any one of the first to fourth inventions, there is provided a heat insulating material having ^{a tensile strength of 20 N / cm 2 or more of the styrene-based resin foamed particle molded product.}

According to the present invention, it is possible to provide a heat insulating material having good thermal conductivity, excellent heat insulating performance, and suitable for architectural use.

It is a figure which shows the example of the apparatus for introducing the preliminary foam particles A and B into a mold. It is a photograph which shows the state after the heat resistance test of the heat-resistant material of Examples 1, 3, 4, 5, 6 and Comparative Examples 1 and 2 at 80 degreeC, 90 degreeC, and 95 degreeC.

Hereinafter, the present invention will be described in detail based on the embodiments.

The heat insulating material of the present invention is a styrene-based resin foamed particle molded body, and the content of the radiant heat transfer inhibitor is 1 to 10% by mass as the styrene-based resin foamed particles constituting the foamed particle molded body. A foamed particle A and a foamed particle B having a radiant heat transfer inhibitor content of less than 1% by mass (including 0) of the foamed particle A in a cross section perpendicular to the thickness direction of the foamed particle molded body. The average value (S1 / S2) of the total area (S1) and the total area (S2) of the foamed particles B is in the range of 0.1 to 4.0.

In a preferred embodiment of the present invention, the foamed particle molded body is composed of a plurality of the foamed particles A and a plurality of fused bodies of the foamed particles B, and the foamed particles A and the foamed particles B are molded into the foamed particles. It is dispersed throughout the body.

Further, in the heat insulating material of the present invention, the area ratio (S1 /) of the total area (S1) of the foamed particles A and the total area (S2) of the foamed particles B in the cross section perpendicular to the thickness direction of the foamed particle molded body. The coefficient of variation of S2) is 40% or less.

Further, in the present invention, the radiant heat transfer inhibitor is particularly preferably graphite and / or carbon black. In the following description, a case where graphite is used as the radiant heat transfer inhibitor will be described as a typical example.

Further, it is desirable that the density of the styrene-based resin foam particle molded product constituting the heat insulating material of the present invention is 10 to 50 kg / m ^3.

In the present specification, the styrene-based resin foamed particle molded product may be referred to as a foamed particle molded product or simply a molded product. Further, the foamed particles A and the foamed particles B may be collectively referred to as foamed particles.

First, an embodiment in which the foamed particle molded product is composed of the foamed particles A and the foamed particles B will be described.
(Expanded particles A)
The foamed particles A containing the radiation inhibitor have a radiation inhibitor content of 1 to 10% by mass. If the content of the radiation inhibitor is too small, it may be difficult to obtain the thermal conductivity (0.037 W / m · K or less) for the desired building application. On the other hand, when the amount of the radiation inhibitor is too large, it becomes difficult for the foamed particles A to be uniformly dispersed and present in the foamed molded product. From the above viewpoint, the content of the radiation inhibitor in the foamed particles A is 1 to 10% by mass, more preferably 2 to 8% by mass, still more preferably 3 to 5% by mass.
(Radiation inhibitor)
Examples of the radiation suppressant include those having an infrared absorption effect and those having an infrared reflection effect, and examples thereof include carbon-based radiation suppressants and inorganic particle-based radiation suppressants other than carbon-based radiation suppressants. Examples of the carbon-based radiation inhibitor include graphite and carbon black, and examples of the inorganic particle-based radiation inhibitor include titanium oxide, zinc oxide, barium sulfate, and aluminum powder.

From the viewpoint of cost and handleability, the radiation inhibitor is preferably a carbon-based radiation inhibitor, and more preferably graphite.
(Expanded particles B)
On the other hand, the foamed particles B are foamed particles obtained by foaming resin particles formed without containing a radiation inhibitor, or resin particles containing a radiation inhibitor in a range of less than 1% by mass. The resulting foamed particles. Further, the content of the radiation inhibitor is preferably 0% by mass to 0.5% by mass.
(Foam particles)
In addition to the radiation inhibitor, other additives may be appropriately contained in both the foamed particles A and the foamed particles B. Examples of the additive include a colorant, a flame retardant, an antistatic agent, and a bubble adjusting agent. The bulk density of the expanded particles A and the expanded beads B is preferably 10~80kg / ^{m 3,} preferably a 12~50kg / ^{m 3.} Within the above range, a good heat insulating material can be obtained. The bulk densities of the foam particles A and the foam particles B may be the same, but foam particles having different bulk densities may also be used. The bulk density was measured by filling the foamed particles up to the marked line position of 1 L in a 1 L graduated cylinder, and weighing the mass WP (unit: g) of the foamed particles having a bulk volume of 1 L to the first decimal place. Then, the bulk density (unit: kg / m ³ ) was obtained by performing unit conversion.
(Expanded particle molded product)
It is preferable that the foamed particle molded body of the present invention is composed of foamed particles A and foamed particles B, and these are present in the foamed particle molded body in a specific dispersed state. From the viewpoint of reducing the thermal conductivity, the blending ratio (volume ratio) of the foamed particles A and the foamed particles B is preferably 10:90 to 70:30, more preferably 15:85-60:40. Yes, more preferably 20:80 to 55:45.

The dispersed state of the foamed particles A and the foamed particles B in the foamed particle molded body is preferably uniformly dispersed, and preferably satisfies the area ratio in the cross section of the foamed particle molded body described later. Furthermore, it is preferable to satisfy the coefficient of variation of the area ratio.
(Density of foamed particle molded product)
The density of the foamed particle molded product is preferably 10 to 50 kg / m ³ and more preferably ^{12 to 25 kg / m 3} from the viewpoint of the balance between heat insulating properties and tensile strength for building applications. Further, 15 to 20 kg / m ³ is preferable.
(Measurement of foam particle molded body density)
Since the density of the foamed particle molded product is an in-mold molded product obtained by the in-mold molding method, it can be obtained by ^{dividing the mass (g) of the molded product sample by the volume (m 3} ) of the molded product sample. .. The volume of the molded product sample can be obtained by a submersion method calculated from the increase in the volume of water when the foamed molded product is submerged.
(Foam particle molded body shape)
The shape of the foamed particle molded product can be appropriately set to various three-dimensional shapes such as a plate shape and a columnar shape for building use. In particular, in the heat insulating material of the present invention, it is not necessary to form a conventional laminated structure, and the heat insulating property of the molded body can be improved by dispersing the foamed particles A and the foamed particles B in the foamed particle molded body. can. If the foamed particles A and the foamed particles B can be uniformly present so as to satisfy the area ratio of the following cross-sectional area and the coefficient of variation of the area ratio, statistically, the number of the foamed particles A in the thickness direction is approximately approximately. Since they are the same, they have uniform heat insulating properties and can exhibit excellent heat insulating properties. Further, since it is not necessary to form the heat insulating layer and the heat insulating material can be formed into a free shape by in-mold molding, the degree of freedom of the shape is excellent.
(Styrene resin)
The styrene-based resin is a styrene-based resin obtained by polymerizing an aromatic vinyl monomer such as styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, and p-ethylstyrene. The styrene-based resin may be the aromatic vinyl monomer alone, a mixture of two or more of these monomers and polymerized, or a mixture of two or more of the resins obtained by polymerizing from the monomer. ..

Further, a styrene resin obtained by copolymerizing a vinyl monomer copolymerizable with an aromatic vinyl monomer may be used.

From the viewpoint of manufacturing cost and foamability when obtaining foamed particles from the foamable resin particles, it is preferable to use a styrene-based resin containing styrene as a main component, and the styrene-based resin contains 50% by weight of the styrene component. As described above, it is preferably contained in an amount of 70% by weight or more, more preferably 90% by weight or more.
(Molecular weight of styrene resin constituting foamed particles)
The molecular weight of the styrene-based resin constituting the foamed particles is preferably in the range of 150,000 to 350,000 in terms of weight average molecular weight (Mw). In particular, when the molecular weights of both the styrene-based resin constituting the foamed particles A and the foamed particles B are within the above range, the foamed particles obtained from the foamable resin particles have good foamability and are foamed at a high foaming ratio. A particle molded body can be obtained, and the foamed particles are easily fused to each other during in-mold molding, and the strength of the obtained foamed particle molded body is improved. The weight average molecular weight (Mw) is preferably 150,000 to 250,000.

The weight average molecular weight, the number average molecular weight, and the Z average molecular weight were measured by dissolving 10 mg of a styrene resin in 10 mL of THF (tetrahydrofuran), measuring by a GPC (gel permeation chromatograph) method, and calibrating with standard polystyrene. The value. For the above GPC analysis, equipment used: Tosoh Co., Ltd., SC-8020 type, column: Showa Denko Co., Ltd., two Shodex AC-80Ms connected in series, column temperature: 40 ° C, flow velocity: 1.0 ml / Min, Detector: UV-8020, an ultraviolet-visible light detector manufactured by Tosoh Corporation, can be used.
(Area ratio)
Regarding the dispersed state of the foamed particles A and the foamed particles B in the foamed particle molded body of the present invention, the total area (S1) of the foamed particles A and the foamed particles B appearing in a cross section perpendicular to the thickness direction of the foamed particle molded body. The average value of the area ratio (S1 / S2) to the total area (S2) of is 0.1 to 4. It may be difficult to exert. If the average value of the area ratio (S1 / S2) is too large, it becomes difficult to uniformly disperse the foamed particles, so that sufficient and reproducible heat insulating performance may not be obtained. From the above viewpoint, the area ratio is more preferably 0.2 to 3, still more preferably 0.25 to 2.
(Measurement method of area ratio)
In the present invention, the above area ratio (S1 / S2) cuts out a total of three cross sections of the foamed particle molded product, two in the central portion in the thickness direction and the other in the surface side portion. Then, on each cross section, the total area (S1) of the plurality of foamed particle A cross sections and the total area of the plurality of foamed particle B cross sections existing in a plurality of squares having a length of 50 mm and a width of 50 mm (S1). It is obtained by obtaining S2) and dividing S1 by S2. Then, an operation for obtaining this area ratio (S1 / S2) is performed for each cross section of the foamed particle molded body, and the area ratios for at least 15 obtained locations (SR1, SR2, ... SR15, respectively). The arithmetic mean value of is taken as the average value (SV) of the area ratio (S1 / S2).

When the cross section of the foamed particle molded product includes a curved surface, the same operation is performed on the sample cut out as a plane cross section, and the area ratio is calculated. The thickness direction means the heat insulating direction used as a heat insulating material.

Further, as a method of calculating S1 and S2 existing in the range of the square selected on the cross section of the foamed particle molded body, for example, first, an enlarged photograph of the area of the square is taken, and the enlarged photograph is taken as a scanner device. Convert to image data with. At this time, as the scanner device, a commercially available scanner device can be appropriately selected. Next, a monotone image is prepared by performing a monotone processing on the image of the enlarged photograph converted into image data. The graphite-containing foamed particles A are displayed as black portions. The monotone processing can be realized, for example, by applying an enlarged photograph converted into image data to image analysis software such as NS2K Pro (nanosystem). The total area of the foamed particles A (S1) is calculated by calculating the area of the black part based on the image data that has been monotone processed, and the total area of the foamed particles A is subtracted from the total area of the image. Then, the total area of the foamed particles B (S2) can be calculated.
(Coefficient of variation of area ratio)
The coefficient of variation of the area ratio (S1 / S2) in the cross section of the foamed particle molded product of the present invention is 40% or less, more preferably 30% or less, still more preferably 25% or less. The small coefficient of variation of the area ratio indicates that each of the foamed particles A and the foamed particles B in the foamed particle molded product is more uniformly dispersed. The lower limit of the coefficient of variation is preferably about 5%.
Conventionally, when forming a heat insulating material, it has been common to obtain a desired heat insulating performance by forming a layer of a molded body composed of only foamed particles A having an excellent effect of reducing thermal conductivity.

On the other hand, when the foamed particles A and the foamed particles B are mixed to form a molded product, since the foamed particles A contain a radiation inhibitor, the weights of the foamed particles A and the foamed particles B per volume. However, it has been considered difficult to obtain a foamed particle molded product having uniform heat insulating properties because the foamed particles A tend to stay under the molding mold during in-mold molding. Therefore, the blending ratio of the expanded particles A and the expanded particles B used in the in-mold molding, and the expanded particles A and the expanded particles B constituting the cross section of the expanded particle molded product obtained by the in-mold molding. The area ratio of is not always the corresponding relationship.

In the present invention, it has been found that a stable effect of reducing thermal conductivity can be obtained by using a molded product in which the foamed particles A are more uniformly dispersed than before as a heat insulating material in the foamed particle molded product. It is a thing. In the present invention, the coefficient of variation of the area ratio is small in the foamed particle molded body, and the foamed particles A are present in a relatively uniformly dispersed state. In this case, the number of foamed particles A that are statistically present in the thickness direction is also uniform. Then, the heat insulating performance in the thickness direction is homogenized, so that the heat insulating performance is excellent. In the present invention, by uniformly introducing the foamed particles into the mold by the method described later, the coefficient of variation of the area ratio becomes small, and excellent heat insulating properties can be exhibited.
(Calculation method of coefficient of variation (%) of area ratio)
In the present invention, the coefficient of variation of the area ratio (S1 / S2) is the value of the area ratio (SR1, SR2, SR3, ... SR14, SR15) of 15 points in the cross section of the foamed particle molded body measured as described above. And from the average value (SV) of the area ratio, it is calculated based on the following mathematical formulas (1) to (3).

(Manufacturing method of foamed particle molded product)
Examples of the method for producing the foamed particle molded product according to the present invention include the following methods.

First, the foamed particles A and the foamed particles B are prepared as follows.

As a method of preparing the resin particles for obtaining the foamed particles B, for example, the base resin is put into an extruder and extruded into a strand shape from a die attached to the tip of the extruder as a molten state, and the extruded strand is cut. Then, a method of obtaining resin particles (strand cut method) and the like can be mentioned. In addition to this method, as a method for preparing resin particles, a well-known method for producing resin particles such as an underwater cut method can be adopted. As the foamed particles A, resin particles in which a foaming agent is contained in a styrene-based resin in which graphite is dispersed in an amount of 1 to 10% by mass as a radiation inhibitor are obtained. As a method for preparing the resin particles for obtaining the foamed particles A, graphite and the styrene resin are dispersed in the styrene resin without being significantly unevenly distributed by using a kneader such as a kneader or an extruder. Other than kneading as described above, a well-known resin particle production method such as the above-mentioned strand cutting method or underwater cutting method can be adopted.

Foamed particles, which are foams of resin particles, are produced by a conventionally known method for producing extruded foamed particles, a method of releasing foamable resin particles containing a foaming agent from an autoclave to foam, and heating the foamable resin particles containing a foaming agent. It can be produced by a conventionally known foaming method such as a method of softening and foaming.

When the foamed particle molded body of the present invention is used as a heat insulating material, it is ideal that the mixed state of the foamed particles A and the foamed particles B constituting the foamed particle molded body is uniform. From the viewpoint of obtaining a foamed particle molded body in which the foamed particles A and the embossed particles B are uniformly mixed, the relationship between the apparent density and the average particle size of the foamed particles A and the foamed particles B is the following mathematical formula (4) and the mathematical formula ( It is preferable to satisfy 5).

ただし、上記数式（４）、数式（５）において、
Ｄ１：発泡粒子Ａの見かけ密度（ｋｇ／ｍ^３）、
Ｄ２：発泡粒子Ｂの見かけ密度（ｋｇ／ｍ^３）、
Ｐ１：発泡粒子Ａの平均粒子径（ｍｍ）、
Ｐ２：発泡粒子Ｂの平均粒子径（ｍｍ）、
である。

However, in the above mathematical formulas (4) and (5),
D1: Apparent density of foamed particles A (kg / m ³ ),
D2: Apparent density of foamed particles B (kg / m ³ ),
P1: Average particle size (mm) of foamed particles A,
P2: Average particle size (mm) of foamed particles B,
Is.

By using the foamed particles satisfying the above formulas (4) and (5), the dispersion of the foamed particles A in the foamed particle molded product can be made more uniform.

The foamed particles A and the foamed particles B are sufficiently mixed using a mixing device or the like to prepare a foamed particle mixture, and the foamed particle mixture is filled in a molding mold and molded in the mold to form a foamed particle molded product. Can be. As the mixing device, a paddle type or screw type mixer, a tumbler, or the like can be appropriately selected.

Further, in the present invention, the foamed particles A and the foamed particles B are stored separately, and when they are introduced into the molding mold, the foamed particles A and the foamed particles in the molded product are foamed by the introduction method as shown in FIG. The dispersed state of the particles B can be controlled to be more uniform. That is, when the foamed particles A and the foamed particles B are transferred to the molding die, the mixing ratio of the foamed particles is controlled by changing the diameter of the pipe to be transferred. Then, immediately before the introduction into the molding die, the pipe for the foamed particles A and the pipe for the foamed particles B are connected to one, and the foamed particles A and the foamed particles B are mixed in the pipe to form the molded product. The foamed particles A and B can be uniformly introduced into the mold. The introduced foamed particles are fused by in-mold molding to obtain a molded product in which the foamed particles A and B are uniformly dispersed in the molded product.

In particular, in the method of FIG. 1 above, one of the foamed particles is unevenly distributed in the mold, such as a flat plate-shaped molded body, different density of the foamed particles, and different weights of the foamed particles. Even if it is easy to carry out, the molded product in which the foamed particles A and the foamed particles B are well dispersed is obtained.

When used as a heat insulating material for construction, for example, in the case of a flat molded body, it is important that the above two types of foam particles are uniformly dispersed on a cross section perpendicular to the thickness direction. It is important that the molded product is evenly dispersed without being biased in the thickness direction. In the present invention, it has been found that the molded product obtained by controlling the dispersion of the two types of foamed particles in the molded product is particularly excellent as a heat insulating material for buildings.

According to the above method, by increasing or decreasing the number of pipes within a range that does not impair the effect of the present invention, it is possible to further mix various types of foamed particles to obtain a molded product.
(Method of measuring the average particle size of foamed particles)
A graduated cylinder containing water is prepared, and an appropriate amount of foamed particles is submerged in the water in the graduated cylinder using a tool such as a wire mesh. Then, the volume V1 [L] of the foamed particles read from the rising water level is measured while considering the volume of the tool such as the wire mesh. By dividing this volume V1 by the number of foamed particles (N) placed in the graduated cylinder (V1 / N), the average volume per foamed particle is calculated. The diameter of the virtual true sphere having the same volume as the obtained average volume was defined as the average particle size [mm] of the foamed particles.
(Tensile strength of foamed particle molded product)
The tensile strength of the foamed particle compact is based on the tensile test method described in JIS K6767: 1999, and a test piece 90 mm × 90 mm × 10 mm (thickness) is pulled in the vertical direction at a speed of 10 mm / min by a tensile test autograph. The maximum load up to cutting is calculated by dividing by the cross-sectional area of the test piece (width of the test piece x thickness of the test piece). Incidentally, the tensile strength of the styrene resin foamed bead molded article is preferably 20 N / cm ² or more, more preferably 21N / cm ² or more.
(Change in heating dimensions)
The obtained heat insulating material is placed horizontally in a hot air circulation type dryer maintained at each temperature of 70 ° C. to 90 ° C. according to JIS K6767 (1999), heated for 22 hours, and then taken out and standardized. The dimensions were measured after being left in the state for 1 hour and before heating.
(Thermal conductivity)
As for the thermal conductivity, a test piece of a foam molded product having a size of 200 mm × 200 mm × 25 mm immediately after production is stored in an atmosphere of 23 ° C. and 50% humidity. 10 days after production, the thermal conductivity was measured using the test piece based on the heat flow metering method described in JIS A1412-2: 1999 (single test piece, symmetrical configuration method, high temperature side 33 ° C., low temperature side 13 ° C.). can do. From the viewpoint of exhibiting excellent performance as a heat insulating material for buildings, the thermal conductivity is preferably 0.037 W / m · K or less, and more preferably 0.0365 W / m · K or less. It is preferably 0.036 W / m · K or less, and more preferably 0.036 W / m · K or less.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.
Example 1
Pre-foamed particles A 13% (vol%) (bulk density 18 kg / m ³ , average particle diameter 4.0 mm) made of polystyrene resin containing 5.5% by mass of commercially available graphite, and commercially available polystyrene-free polystyrene resin Preliminary foamed particles B of 87% (vol%) (bulk density 18 kg / m ³ , average particle diameter 4.0 mm) were separately prepared, and these were filled in an in-mold molding machine by the method described later. The graphite ratio to the entire molded product was 0.8% by mass.

Then, the prefoamed particles filled in the mold with steam of 0.09 MPa (gauge pressure) were heated for 15 seconds. As a result, the pre-foamed particles were fused to each other in the mold. Next, after cooling the inside of the mold for a predetermined time, the foamed particle molded product in which the preliminary foamed particles were fused to each other was taken out from the mold to produce the heat insulating material of Example 1. The dimensions of this heat insulating material were a bottom surface of 200 mm × 200 mm, a thickness of 25 mm, and a density of 16 kg / m ³ . The mixing ratio of the preliminary foamed particles A and B is adjusted according to the pipe diameter when the preliminary foamed particles A and B are introduced into the mold, and the pipes of the preliminary foamed particles A and B are merged once before the mold is introduced and then mixed in the pipe. The foamed particle group was introduced from the filling gun into the mold. For the introduction of the preliminary foamed particles A and B into the mold, as shown in FIG. 1, the tip of the foamed particle-filled hose is bifurcated (Y-shaped pipe), and the pipe diameter (cross-sectional area) thereof is set to an appropriate ratio. As a result, a molded product having a uniform mixing ratio can be obtained. In the first embodiment, the diameter of the pipe on the foam particle B side is 25 mm, and the cross-sectional area of the pipe on the foam particle A side is 18% of the cross-sectional area of the pipe of the foam particle B. It was controlled to 13%.

Average area ratio (S1 / S2), coefficient of variation of area ratio, standard deviation (σ), molded body density, thermal conductivity, dimensional change (70 ° C, 80 ° C, 85 ° C,) of the heat insulating material prepared in Example 1. 90 ° C., 95 ° C.), tensile strength A was measured by the method described above. The results are shown in Tables 1 and 2. The area ratio was measured by cutting out a cross section of 5 mm from the central portion of the molded body and the surface of the molded body. From Table 1, it can be seen that the heat insulating material of Example 1 has good thermal conductivity, excellent heat insulating performance, and excellent tensile strength.

Further, from Table 2, it can be seen that the heat insulating material having a larger blending ratio of the foamed particles A has a smaller change in heating dimensions. This is because the foamed particles A containing graphite particles are prone to heat dissipation, and the foamed particles having such characteristics are uniformly dispersed in the foamed particle molded body, so that it is considered that the change in heating dimension is small. .. From the above viewpoint, the blending ratio (volume ratio) of the foamed particles A and the foamed particles B is preferably 30:70 to 70:30.

Examples 2-6
The heat insulating materials of Examples 2 to 6 were produced in the same manner as in Example 1 except that the blending ratios of the foamed particles A and the foamed particles B were shown in Table 1. The filling ratio of each of the foamed particles was controlled by keeping the piping of the foamed particles B in Example 1 constant and changing the cross-sectional area of the piping of the foamed particles A. In Example 2, the ratio X of the cross-sectional area of the foamed particle A pipe to the foamed particle B pipe is 36%, in Example 3, X is 42%, in Example 4, 55%, and in Example 5. It was set to 100%. Therefore, the filling ratio of each foamed particle can be controlled by changing the cross-sectional area of the pipe. The foamed particle molded body molded in the mold as described above has a total area (S1) of the foamed particles A and a total area (S2) of the foamed particles B in a cross section perpendicular to the thickness direction of the foamed particle molded body. The average value of the area ratio (S1 / S2) with and was in the range of 0.1 to 4.0, the coefficient of variation of the area ratio was 40% or less, and the dispersibility of the foamed particles was excellent.

Various characteristics of these heat insulating materials were investigated in the same manner as in Example 1. The results are shown in Table 1.
Comparative Example 1
The heat insulating material of Comparative Example 1 was produced in the same manner as in Example 1 using only the foamed particles B.

The various characteristics shown in Table 1 were investigated for the heat insulating material of Comparative Example 1. The results are shown in Table 1. From Table 1, the heat insulating material of Comparative Example 1 has a large thermal conductivity and is inferior in heat insulating property.
Comparative Example 2
Using only the foamed particles A, the heat insulating material of Comparative Example 2 was produced in the same manner as in Example 1.

The various characteristics shown in Table 1 were investigated for the heat insulating material of Comparative Example 2.
Comparative Example 3
A foamed particle molded product prepared in the same manner as in Example 1 using only the foamed particles A and a foamed particle molded product prepared in the same manner as in Example 1 using only the foamed particles B have a thickness of 1: 2. The heat insulating material of Comparative Example 3 was produced by laminating the molded articles so as to have a thickness of 25 mm.

The various characteristics shown in Table 1 were investigated for the heat insulating material of Comparative Example 3. The results are shown in Table 1.

In Comparative Example 3, since there is a laminated adhesive surface between the molded body of the foamed particles A and the molded body of the foamed particles B, the tensile strength greatly fluctuates depending on the measurement location. In particular, if there is a portion having insufficient adhesive strength, the portion may be locally broken and the tensile strength may decrease.

Claims (7)

Styrene-based resin foamed particle molded product
As the styrene-based resin foamed particles constituting the foamed particle molded body, the foamed particles A having a radiant heat transfer inhibitor content of 1 to 10% by mass and the radiant heat transfer inhibitor content of 1 mass. Contains less than% (including 0) foam particles B,
The radiant heat transfer inhibitor is dispersed in the styrene resin constituting the foamed particles A.
The average value (S1 / S2) of the area ratio (S1 / S2) of the total area (S1) of the foamed particles A and the total area (S2) of the foamed particles B in the cross section perpendicular to the thickness direction of the foamed particle molded body is 0.1. A heat insulating material having a range of about 4.0 and having a coefficient of variation of the area ratio calculated from the following equation (1) of 40% or less.
Coefficient of variation = (standard deviation / SV) x 100 ... (1)
(However, the standard deviation is the standard deviation calculated from the area ratio of 15 points in the cross section of the foamed particle molded body, and SV is the average value of the area ratio of 15 points in the cross section of the foamed particle molded body.) The heat insulating material according to claim 1, wherein the radiant heat transfer inhibitor is graphite. The heat insulating material according to claim 1 or 2, wherein the density of the styrene-based resin foamed particle molded product is 10 to 50 kg / m ^3. The heat insulating material according to any one of claims 1 to 3, wherein the styrene-based resin foamed particle molded body has a thermal conductivity of 0.037 W / m · K or less. The heat insulating material according to any one of claims 1 to 4, wherein the styrene-based resin foamed particle molded product has a tensile strength of 20 N / cm ^{2 or more.} The heat insulating material according to any one of claims 1 to 5, wherein the blending ratio (volume ratio) of the foamed particles A and the foamed particles B is 30:70 to 70:30. The heat insulating material according to any one of claims 1 to 6, wherein the foamed particles A and the foamed particles B satisfy the following formulas (2) and (3).
0.8 ≤ D1 / D2 ≤ 1.2 ... (2)
0.8 ≤ P1 / P2 ≤ 1.2 ... (3)
(However, in the above formulas (2) and (3), D1: the apparent density of the foamed particles A (kg / m). ³ ), D2: Apparent density of foamed particles B (kg / m) ³ ), P1: Average particle size of foamed particles A (mm), P2: Average particle size of foamed particles B (mm))

Images