JP2001316508A - Styrenic resin extrusion foam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a styrenic resin extrusion foam having low heat conductivity, excellent heat insulation performances and environmental compatibility. SOLUTION: This styrenic resin extrusion molding foam is a styrene-based resin foam having 20-100 kg/m3 density in which, with respect to cell diameters in the extrusion direction, cell diameters in the width direction and cell diameters in the thickness direction, average values A, B and C of the cell diameters in the directions and variances Va, VB and Cc of the cell diameters in the directions have a specific relation and a heat conductivity λresin (W/mK) of resin, a heat conductivity λgas (W/mK) of a gas in a foam cell, an expansion ratio ϕ calculated by the ratio of a resin density (kg/m3) to a foam density (kg/m3)=resin density/foam density, an average cell diameter R (mm) calculated from the cube root of the product ABC of the average value A (mm) of cell diameters in the extrusion direction, the average value B (mm) of cell diameters in the width direction and the average value C (mm) of cell diameters in the thickness direction=(ABC)1/3, a cell diameter ratio k1=C/A and k2=C/B calculated from ratios of the cell diameter C in the direction of the heat conductivity measurement to the cell diameters A and B in the two directions perpendicular to the direction of the heat conductivity measurement have a specific relation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an extruded styrene resin foam having excellent heat insulation properties, and more particularly, to an extruded styrene resin foam having low heat conductivity, excellent heat insulation performance and excellent environmental compatibility. About the body.

[0002]

2. Description of the Related Art In general, the thermal conductivity of a synthetic resin foam is determined by its heat transfer mechanism as follows: (a) conduction between a solid phase (resin) and a gas phase (gas in a cell); c) Divided into convection of gas in the cell. Among them, the convection of the gas in the cell (c) is recognized when the cell diameter is 4 mm or more and is negligible in a normal resin foam. Therefore, a factor affecting the thermal conductivity of a normal synthetic resin foam. (A) is the conduction between the solid phase (resin) and the gas phase (cell) and (b) is the radiation between the cell films.

[0003] First, regarding (a), in a high-magnification foam, the volume occupied by the resin is small and the volume occupied by the cell is large. The ratio of conduction to thermal conductivity is large.
Since the thermal conductivity of the gas phase is very small compared to the thermal conductivity of the solid phase, a foam having a low thermal conductivity may be obtained by increasing the expansion ratio. Further, in order to obtain a foam having higher heat insulation performance, it is necessary to lower the thermal conductivity in the gas phase. For this purpose, the gas in the cell must have low thermal conductivity and low permeation in the resin, and the selection of the foaming agent used in the production of the foam greatly affects the heat insulation performance of the foam. I can say that.

Heretofore, so-called fluorocarbons and hydrocarbons have been proposed as foaming agents for styrene resin foams, or are used industrially.

[0005] For example, as for fluorocarbons, chlorine atom-containing halogenated carbon (hereinafter abbreviated as CFC) tends to remain in the foam, so that a good foam is formed and the thermal conductivity is low. Therefore, it has been used to contribute to heat insulation. However, it has been pointed out that this CFC affects the ozone layer in recent years, and its use has been avoided. Under such circumstances, various attempts to satisfy environmental compatibility have been proposed.
As a substitute for C, a chlorinated fluorinated hydrocarbon having a structure in which a part of chlorine atoms of CFC is replaced by hydrogen atoms (hereinafter referred to as HCF)
There has been proposed a method using fluorinated hydrocarbons (hereinafter abbreviated as HFC) which is a CFC-free chlorofluorocarbon. It is generally said that HFCs have no possibility of affecting the ozone layer, and are more preferable than HCFCs from the viewpoint of environmental compatibility. However, HC
It is said that fluorocarbons such as FC and HFC are less likely to affect the ozone layer than CFCs, but are preferably reduced as much as possible, taking into account the impact on global warming.

Further, isobutane (i-butane) and normal butane (n-
Japanese Patent Application Laid-Open No. 1-17 / 1990 discloses that a foam having excellent heat insulating properties can be obtained by combining butane) and using it as a foaming agent.
No. 4540 discloses this.

[0007] Next, regarding the radiation between the cell films in (b), the effect of attenuating the radiation heat transfer by the cell film surface is large in the foam. Therefore, it is said that it largely depends on the cell structure such as the expansion ratio, cell diameter and cell diameter ratio of the foam. For example, the smaller the cell diameter in the heat flow direction at the time of measuring the heat conductivity, the greater the number of times the heat flow is shielded per unit thickness, and as a result, the lower the heat conductivity. However, if the cell diameter is too small, the cell thickness becomes too small, and the effect of the function of shielding the radiant heat by the cell film becomes small, so that the conduction by radiation increases and the thermal conductivity increases. Further, when the expansion ratio is large, the cell diameter becomes larger or the cell thickness becomes smaller than when the expansion ratio is small. When the cell diameter is large, the number of times of shielding radiant heat is reduced, so that the conduction by radiation increases and the thermal conductivity increases. On the other hand, when the cell film thickness is small, the effect of the function of shielding the radiant heat by the cell film is reduced, so that the conduction by radiation increases and the thermal conductivity increases. In order to reduce radiant heat transfer and lower the thermal conductivity, it is necessary to reduce the expansion ratio. Cell diameter ratio, that is, when the value defined by the ratio of the cell diameter in the heat flow direction and the cell diameter in the direction orthogonal thereto increases, first, the number of times of radiant heat shielding decreases because the cell diameter in the heat flow direction increases. Thermal conductivity increases. Second, the effect of radiant heat from the cell film in the direction parallel to the heat flow increases, so that radiant heat transfer increases and the thermal conductivity increases.
In order to reduce radiant heat transfer, it is necessary to reduce the cell diameter ratio.

In order to reduce the thermal conductivity by reducing the conduction between the resin and the gas in the cell and the radiation due to the radiation between the cell films, the thermal conductivity, the expansion ratio, the cell diameter and the cell diameter ratio of the gas in the cell are required. Need to be controlled.

[0009] In WO 97/17396 pamphlet, a styrene-based resin foam having excellent heat insulation performance can be obtained by setting an average cell diameter in an appropriate region according to the foam density. Is disclosed. However, since it is intended for a high expansion ratio with a cell diameter ratio of 50 times or more, the ratio of radiant heat transfer is higher than that of a foam having a lower expansion ratio.
Further improvement is desired in order to obtain a foam having a high heat insulating performance that can further satisfy the standards of Class B Class 2 and Class B Class 3 heat insulating plates specified in A9511.

[0010] WO 99/33625 discloses that a styrene-based resin foam has excellent heat insulating performance by controlling the cell diameter ratio to 1 or less while using an environmentally compatible foaming agent. It is disclosed that a styrene resin extruded foam having the same can be obtained. The cell diameter ratio is certainly one of the factors that determine the thermal conductivity of the foam, but the thermal conductivity is low if optimized taking into account the thermal conductivity of the gas in the cell, the expansion ratio, and the average cell diameter Excellent foams may be obtained.

As described above, although various technical approaches have been taken, further improvement is desired in order to obtain an industrially useful foam having, for example, high thermal insulation performance while being environmentally compatible. It is rare.

[0012]

In the prior art as described above, the thermal conductivity of the resin, the thermal conductivity of the gas in the cell, and the foaming of the foam are factors that determine the thermal conductivity of the foam. Attention has been paid to a part of the magnification, the average cell diameter, and the cell diameter ratio. The present invention has been made in view of the above circumstances, the thermal conductivity of the resin, the thermal conductivity of the gas in the cell, and the optimal average cell diameter and cell diameter ratio according to the expansion ratio of the foam. An object of the present invention is to obtain a styrene-based resin extruded foam having high heat insulation performance and excellent environmental compatibility by selecting and increasing the dispersion of cell diameters.

[0013]

According to a first aspect of the present invention, there is provided a styrene resin extruded foam which does not use fluorocarbons as a foaming agent.
0 kg / m ³ , and the cell diameter in the extrusion direction, the cell diameter in the width direction, and the cell diameter in the thickness direction, and the average values A, B, and C of the cell diameters in each direction and the dispersion of the cell diameters in each direction. V _A , V _B ,
Between V _C

[0014]

(Equation 3)

Having the relationship described above, and the thermal conductivity of the resin,
Thermal conductivity of gas in the foam cell, expansion ratio, average cell diameter, between the cell diameter ratio,

[0016]

(Equation 4)

The present invention provides an extruded styrene resin foam having the following relationship.

Further, according to the present invention, the thermal conductivity of the foam is JI
The extruded styrene resin foam according to S-A9511, characterized in that the styrene resin extruded foam is 0.028 W / mK or less as measured by a method for measuring a class B heat insulating plate.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the equation (2) will be described. The form of the equation (2) is an inequality, and the thermal conductivity and the foaming of the resin necessary for the foam to have a high heat insulating performance are described. Thermal conductivity of gas in body cell, expansion ratio, average cell diameter,
It shows the relationship such as the cell diameter ratio. The left side of the equation (2) is a dimensionless amount of the heat flow flowing through the foam when measuring the thermal conductivity of the foam. Further, the first term on the left side of the equation (2) means a heat flow due to conduction between the resin and the gas in the cell, and the second term on the left side of the equation (2) means a heat flow due to radiation between the cell films.

For example, when factors other than the thermal conductivity value of the gas in the cell in equation (2) are fixed and the thermal conductivity value of the gas in the cell is reduced, the first term on the left side of equation (2) becomes smaller. This makes it easier to satisfy the expression (2) and increases the possibility of having excellent heat insulating performance.

For example, if all factors other than the expansion ratio in equation (2) are fixed and the expansion ratio is increased from a small value, the first term on the left side of equation (2) decreases monotonically. , The second term initially decreases, but increases after a certain value. This is because when the expansion ratio of the left side of the equation (2) increases, the thermal conductivity value decreases at first because the heat transfer contribution by the resin decreases, but when increasing to a certain value or more, the cell thickness increases. This is because a too thin layer shows a physical phenomenon that the radiation heat shielding effect is reduced and the thermal conductivity value is increased.

For example, if all factors other than the average cell diameter in equation (2) are fixed and the average cell diameter is decreased from a large value, the first term on the left side of equation (2) does not change. , The second term initially decreases and increases at a certain value. This is because, when the average cell diameter is reduced on the left side of the equation (2), the thermal conductivity value is also reduced due to an increase in the number of cell films per unit thickness, thereby increasing the effect of shielding radiant heat. This is because a physical phenomenon in which the cell thickness becomes too thin, the radiant heat shielding effect is reduced, and the thermal conductivity value is increased when the cell thickness is increased to the value or more.

Further, for example, when all the factors other than the cell diameter ratio in equation (2) are fixed and the cell diameter ratio is reduced from a large value, the first term on the left side of equation (2) monotonically decreases. However, the second term initially decreases and then increases after a certain value. This is because, when the cell diameter ratio is reduced on the left side of the equation (2), the number of cell films per unit thickness increases at first, so that the effect of shielding radiant heat increases, so that the thermal conductivity value also decreases. This is because when the value exceeds the above value, a physical phenomenon in which the thickness of the cell film becomes too thin, the radiant heat shielding effect decreases, and the thermal conductivity value increases.

As described above, the left side of the equation (2) represents the heat flow in the foam at the time of measuring the thermal conductivity of the foam, and the thermal conductivity of the gas in the foam cell, the expansion ratio, and the average cell diameter. By controlling the cell diameter ratio and satisfying the expression (2), it becomes easy to obtain a foam having high heat insulating performance.

In order to control the expansion ratio, the amount of the blowing agent, the temperature during foaming, and the like are controlled. For example, in order to increase the expansion ratio, a method of increasing the amount of the foaming agent or increasing the temperature at the time of foaming is used alone or in combination.

In order to control the average cell diameter, the type and amount of the foaming agent, the type and amount of the nucleating agent, the pressure release speed during foaming, and the like are controlled. For example, to reduce the average cell diameter, select a blowing agent type with low solubility in styrene resin,
A single method or a combination of a plurality of methods such as increasing the amount of a foaming agent, selecting a nucleating agent having a high nucleating effect, increasing the amount of a nucleating agent, and increasing the pressure release rate during foaming are performed.

In order to control the cell diameter ratio, a method of heating and stretching a foam is used. For example, the cell diameter ratio can be reduced by rotating a roll while applying heat to the foam while heating the foam using a heating device having a roll which is kept warm by heated air.

When fluorocarbons having a small thermal conductivity are not used as the foaming agent, a foaming agent having a slightly higher thermal conductivity than the fluorocarbons is inevitably used. At this time, the condition ranges such as the expansion ratio, the average cell diameter, and the cell diameter ratio for satisfying the expression (2) are slightly narrower than when fluorocarbons are used as the foaming agent. By controlling the expansion ratio, cell diameter, and cell diameter ratio with
And a foam having high heat insulation performance can be obtained.

Next, the equation (1) will be described. The equation (1) means that the cell diameter distribution in each direction has a certain extent. When the thermal conductivity of the resin, the thermal conductivity of the gas in the foam cell, the expansion ratio, the average cell diameter and the cell diameter ratio are the same, the larger the spread of the cell diameter distribution, the thicker the average cell thickness. Therefore, heat flow due to radiation can be further suppressed, and the thermal conductivity value can be further reduced. In Expression (1), the upper limit of the value on the left side of each inequality is about 1.

In order to control the cell diameter distribution so as to satisfy the formula (1), a liquid having a boiling point in the range of 70 to 100 ° C., such as water or alcohol, is added or injected in addition to a commonly used blowing agent. . While a normal foaming agent starts foaming at about the saturation pressure in the extruder, water and alcohol start foaming near the atmospheric pressure, so that a foam having cells of roughly two types, large and small, is obtained. be able to. By adjusting the amount of water or alcohol, the amount of the foaming agent, the amount of the nucleating agent, the pressure release rate, and the like, the distribution of the cell diameter can be controlled so as to satisfy Expression (1).

In the present invention, as long as the obtained styrene resin extruded foam satisfies the above formulas (1) and (2), the styrene resin used, the foaming agent, other additives, and the extruded foam may be used. Conditions are not particularly limited.

For example, as the styrene resin, homopolymers or two kinds of styrene monomers such as styrene, methyl styrene, ethyl styrene, isopropyl styrene, dimethyl styrene, bromo styrene, chloro styrene, vinyl toluene and vinyl xylene can be used. A copolymer comprising a combination of the above monomers and the styrene monomer and divinylbenzene, butadiene, acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, acrylonitrile, maleic anhydride, itaconic anhydride And copolymers obtained by copolymerizing one or two or more of such monomers. Monomers such as acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, maleic anhydride, and itaconic anhydride to be copolymerized with the styrene-based monomer are used for the compression strength of the extruded styrene-based resin foam to be produced. Can be used in such an amount that the physical properties of the polymer are not reduced.
Further, the styrene resin used in the present invention is not limited to the homopolymer or copolymer of the styrene monomer, and the homopolymer or copolymer of the styrene monomer and the other monomer may be used. It may be a homopolymer or a blend with a copolymer, or may be a blend of diene rubber reinforced polystyrene or acrylic rubber reinforced polystyrene.

As the foaming agent, a foaming agent conventionally used except for fluorocarbons can be used without any particular limitation. A blowing agent having a molecular weight smaller than that of air in terms of molecular weight tends to be difficult to use in the present invention, but can be suitably used in combination with a blowing agent having a large molecular weight. Examples of the foaming agent that can be used in the present invention include ethers such as dimethyl ether, diethyl ether, methyl ethyl ether, isopropyl ether, n-butyl ether, diisoamyl ether, furan, furfural, 2-methylfuran, tetrahydrofuran, and tetrahydropyran; Hydrocarbons such as propane, n-butane, i-butane, n-pentane, i-pentane, neopentane, methyl formate, ethyl formate, propyl formate, butyl formate, amyl formate, methyl propionate, Carboxylic acid esters such as ethyl propionate, methanol, ethanol, propyl alcohol, i-propyl alcohol, butyl alcohol, i-butyl alcohol, t-butyl alcohol Which alcohols, dimethyl ketone, methyl ethyl ketone, diethyl ketone, methyl -n- propyl ketone, methyl -n- butyl ketone, methyl -i- ketone,
Organic blowing agents such as ketones such as methyl-n-amyl ketone, methyl-n-hexyl ketone, ethyl-n-propyl ketone, and ethyl-n-butyl ketone can be used alone or in combination of two or more. Carbon dioxide, nitrogen,
Inorganic blowing agents such as water, argon, helium and the like can also be used. These organic foaming agents and inorganic foaming agents can be used in combination.

In the present invention, a foam having excellent environmental compatibility, excellent foaming properties, and excellent physical properties can be easily obtained.
Further, from the viewpoint of easily satisfying the above formulas (1) and (2), the blowing agent is mainly composed of one or more ethers selected from the group consisting of dimethyl ether, diethyl ether and methyl ethyl ether, and carbon Number 3-5
A blowing agent containing one or more saturated hydrocarbons selected from the group consisting of saturated hydrocarbons is particularly preferred. From the viewpoint of easily satisfying the formula (1), it is preferable to use water and / or alcohol in combination with the specific blowing agent.

In the present invention, in addition to the above components, nucleating agents such as silica, talc, calcium silicate, wollastonite, kaolin, clay, mica, zinc oxide and titanium oxide, calcium stearate and barium stearate, etc. And additives such as a flame retardant such as hexabromocyclododecane and an antioxidant such as a polymer type hindered phenol compound. When water is used as the foaming agent, it is preferable to mix an inorganic powder having a large number of hydroxyl groups on the surface or a water-absorbing polymer compound.

The extruded styrene resin foam of the present invention can be produced by a conventional extrusion foaming technique. That is, the styrenic resin is heated and melted in an extruder or the like, and a foaming agent is injected into the styrenic resin under high-pressure conditions to form a fluid gel, and cooled to a temperature suitable for extrusion foaming. By extruding and foaming a styrene resin extruded foam in the region of (1). The pressure at which the foaming agent is injected is not particularly limited, and may be any pressure as long as it is higher than the internal pressure of the extruder to be injected into the extruder. There is no particular limitation on the heating temperature, melting time and melting means when heating and melting the styrene resin. The heating temperature may be higher than the temperature at which the styrene resin is melted, usually about 150 to 250 ° C. The melting time cannot be unequivocally determined because it differs depending on the extrusion amount per unit time, the melting means, and the like, but the time required for uniformly dispersing and mixing the styrene resin and the foaming agent is selected. The melting means is not particularly limited as long as it is used at the time of ordinary extrusion foaming such as a screw type extruder.

Thus, according to the present invention, without using fluorocarbons as a foaming agent, the thermal conductivity is reduced according to JIS-A95.
In the measurement by the method for measuring a Class B heat insulating plate specified in 11, an extruded styrene-based resin foam of 0.028 W / mK or less can be easily obtained.

[0038]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will be described below for the understanding of the present invention. The following embodiments are examples embodying the present invention, and do not limit the scope of the present invention. Also, unless otherwise noted,
Represents parts by weight, and "%" represents% by weight.

In the examples, the expansion ratio, the average cell diameter and the cell diameter ratio, the thermal conductivity of the gas in the resin and the foam cells, the thermal conductivity of the foam, the environmental compatibility, and the formulas (1), (1) Whether or not 2) was satisfied was examined according to the following method.

1) Expansion ratio The approximate density of the styrene resin used was 1050 k.
g / m ³ , which is obtained from the following equation. Expansion ratio (times) = 1050 / density of foam (kg /
m ³ )

The density of the foam is calculated from the weight of the foam and the volume obtained by the submersion method.

2) Average cell diameter, dispersion of cell diameter and cell diameter ratio The vertical section along the extrusion direction and the cross section perpendicular to the extrusion direction of the extruded foam were measured with a scanning electron microscope (manufactured by Hitachi, Ltd., : S-450), take a photograph at a magnification of 30 times, and copy the photographed photograph with a dry copying machine. On the copied image, three to five straight lines are drawn in the extrusion direction, width direction, and thickness direction of the foam. Note that each straight line is drawn except for a partially missing cell located at the end of the image.
By dividing the line length by the number of cells included on each straight line, average values A, B, and C of cell diameters in each direction are obtained. Further, by substituting the line length of the individual cells included in the straight line in Equation proviso of the formula (1), the variance V _A of the cell diameter in each direction, V _B, obtains the V _C. With respect to the obtained average values A, B, and C of the cell diameters in the respective directions, the cube root of the product of them is calculated and defined as the average cell diameter of the foam. In addition, C / A and C / B are obtained and defined as a cell diameter ratio.

3) Thermal conductivity of gas in synthetic resin and gas in foam cell The gas composition in the foam is measured by gas chromatography. In the measurement, a test piece is cut out from the center of the foam, and the measurement is made at the time when 6 months have passed after the production. Next, the molar ratio of each detected gas is calculated, and the molar ratio is used as a weight to determine the normal temperature of each gas (for example, 2
The average value of the literature values of the thermal conductivity at 0 to 25 ° C) is defined as the thermal conductivity of the gas in the cell. The thermal conductivity value of the gas is
The following values were used:

Dimethyl ether: 0.016 W / mK i-butane: 0.018 W / mK i-pentane: 0.0140 W / mK HFC134a: 0.0131 W / mK HCFC142b: 0.0113 W / mK Carbon dioxide: 0.0166 W / mK Ethyl alcohol: 0.0150 W / mK Water: 0.610 W / mK (27 ° C.)

The thermal conductivity of the resin is set to 0.11 W / mK from the thermal conductivity of the styrene resin used.

4) Thermal Conductivity of Foam The thermal conductivity is measured according to JIS A9511. In the measurement, a test piece is cut out from the center of the foam, and the measurement is made at the time when 6 months have passed after the production.

5) Environmental compatibility The degree of environmental compatibility is indicated by a star. The higher the number of stars, the better the environmental compatibility.

6) Judgment as to Whether Equation (1) is Satisfied The average cell diameter and variance in each direction obtained in the above 2) are substituted into Equation (1) to calculate the value on the left side of each inequality. .

7) Judgment as to Whether Equation (2) is Satisfied The values obtained in the above 1) to 3) are substituted into Equation (2) to judge whether or not the inequality is satisfied. ：: Formula (2) is satisfied X: Formula (2) is not satisfied

Example 1 Polystyrene resin (A & M Polystyrene Co., Ltd., trade name: G9401, melt index (MI): 2.
0) To 100 parts, 0.1 part of talc as a nucleating agent, 1.0 part of bentonite as a dispersant of water, and 3.0 parts of hexabromocyclododecane (abbreviated as HBCD) as a flame retardant were added, and added for 1 hour. Per kg of the extruder, heated to 200 ° C. in the extruder and kneaded while adding dimethyl ether 20%, i-butane 70
% And water 10% with a polystyrene resin 1
A total of 8 parts per 100 parts was injected, and the temperature was raised to 115 ° C. through a cooling and mixing machine. A slit having an aperture interval of 2 mm and a molding die having a flow path surface coated with a fluororesin and having a thickness direction interval of 60 mm were used. To obtain a plate-like styrene resin foam. Table 1 shows the evaluation results.

The foam obtained is obtained by the formulas (1) and (2)
At the same time, the thermal conductivity value of 0.028W
/ MK or less.

Examples 2 to 5 A foam was obtained by performing the same operation as in Example 1 except that the composition of the blowing agent was changed as shown in Table 1. In addition,
In Examples 2 and 4, immediately after extrusion, the outlet heating roll was rotated while being reheated for about 1 minute and 20 seconds by a reheating device which was kept warm with heated air at about 140 ° C. and had a pulling roll at the outlet, and formed a foam. Add a stretching process. Table 1 shows the evaluation results.

The foam obtained satisfies the relations of the formulas (1) and (2) at the same time as the foam of Example 1, and is excellent in heat insulation with a thermal conductivity value of 0.028 W / mK or less. It is a foam.

Comparative Examples 1 to 5 A foam was obtained by performing the same operation as in Example 1 except that the composition of the blowing agent was changed as shown in Table 2. In addition,
About the comparative example 2, immediately after the extrusion, the reheating device was kept warm with the heated air at about 140 ° C. and had a take-off roll at the outlet.
The outlet take-up roll is rotated while reheating for about 1 minute and 20 seconds, and the foam is stretched. Table 2 shows the evaluation results.

The foam obtained is obtained by the formulas (1) and (2)
Are not satisfied at the same time, and the thermal conductivity value is 0.0
It is a foam having poor heat insulation properties exceeding 28 W / mK.

[0056]

[Table 1]

[0057]

[Table 2]

[0058]

The extruded styrene-based resin foam according to the present invention has a low thermal conductivity, is excellent in heat insulation performance, and is excellent in environmental compatibility since it is constituted as described above.

Claims (2)

[Claims] An extruded styrenic resin foam not using freon as a foaming agent, having a density of 20 to 100 k
g / m ³ , and the cell diameters in the extrusion direction, the cell diameter in the width direction, and the cell diameter in the thickness direction, and the average values A, B, and C of the cell diameters in each direction and the dispersion of the cell diameters in each direction. V _A , V _B , V _C
Between: And the thermal conductivity of the _resin λ _resin (W / m
K), thermal conductivity λ _gas (W / m) of the gas in the foam cell
K), expansion ratio Φ (= resin density / foam density), average cell diameter A (mm) in the extrusion direction, average cell diameter B (mm) in the width direction, and average cell diameter in the thickness direction Value C
(Mm) The average cell diameter R (mm) (= (ABC) ^1/3 ) calculated from the cube root of ABC and the cell diameter ratio k ₁ (= C) calculated from the ratio of A, B, and C / A) and k ₂ (= C /
B) A styrene resin extruded foam characterized by having the following relationship: 2. The thermal conductivity of the foam is JIS-A9511.
In the measurement by the method of measuring the type B heat insulating plate specified in
2. The extruded styrene-based resin foam according to claim 1, wherein the foam is 0.028 W / mK or less.