JPS6345936B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a new styrene foam board, and more specifically, for example, it can be used as is or pressed into a desired shape as an interior insulation material for structures that receive heat of around 90 degrees Celsius, and as a heat sterilizable insulation material. This invention relates to a new styrene foam board that can be used for containers, insulated containers that can withstand electron beam cooking, etc. Conventionally, polystyrene foams molded in bead molds or extruded have been used for a long time as insulation materials for buildings, cushioning materials for packaging goods, etc. because they are rigid, have excellent heat insulation properties, and also have cushioning properties. In addition, it is widely used in trays, food containers, seedling boxes, seafood transportation boxes, etc. However, these conventional styrene foams have poor heat resistance as shown by the rate of dimensional change when subjected to heat of, for example, around 90°C. Also, the combustion speed when ignited is high. Furthermore, it has drawbacks such as denting and cracking when subjected to impact, and at present it is used for purposes that avoid these drawbacks. The reason for this is that, for example, if you try to improve the heat resistance, the impact resistance will decrease, and if you try to alleviate this, the insulation performance will decrease, and if you try to slow the combustion rate by using flame retardants etc. In other words, it was not possible to achieve a satisfactory level of heat resistance, heat insulation, flame retardancy, formability, suitability for food, etc. In recent years, energy conservation issues have been emphasized, and aircraft,
As ships and vehicles become lighter, issues such as interior insulation materials, thermal insulation materials to collect solar heat, and roof and wall insulation materials to maintain the livability of buildings have become issues. Popularization requires the emergence of food container materials with excellent heat resistance and insulation properties. The present invention was finally completed as a result of intensive research in view of the actual market conditions, and its objectives are to improve heat resistance, heat insulation, flame resistance, impact resistance, surface hardness, suitability for food, All of the aptitude for shaping, etc.
It is an object of the present invention to economically provide a novel styrenic resin foam board that has a sufficient level of functionality for practical use. According to the invention, acrylic acid, methacrylic acid,
The styrene component containing at least one component of maleic anhydride is 75 to 95% by weight, and the softening point is
It is a foamed board with a density of 60 to 200 kg/m ³ and a wall thickness of 2.5 to 7 mm, which is made of styrene copolymer resin at a temperature of 115°C or higher, and the board has a thickness of the skin (T) and the inside of the board. The board has skin parts on both sides that satisfy the relationship (T/t)≧2.5 with the thickness (t) of the bubble film of the bubbles located at The deflection coefficient (p/y) when bent is 1.5
≧ (p/y) ≧ 0.2. However, the deflection coefficient (p/y) has a substantially linear relationship between the amount of deflection (y) and the load (p). The coefficient at the part where (p/y)=E・4bh ³ /l ³ p; Load (Kg) l; Span distance (cm) [20cm was adopted] b; Width of foam board piece (cm) [7.5cm was adopted] h; Foaming Thickness of plate piece (cm) [according to each measurement] E: Flexural modulus (Kg/cm ² ) [according to JIS A-9511 polystyrene foam] y: Deflection amount (cm) The content of the present invention will be explained below with reference to drawings, etc. This will be explained in detail using FIG. 1 is an enlarged photograph of a cross-sectional portion of a foam board of the present invention, and FIGS. 2 and 3 are comparative foam boards. The first feature of the foam of the present invention is that, as is clear from the comparison between FIGS. It has on both sides, and both surfaces are substantially covered with this skin part. This feature cannot be observed in the comparative foam board shown in Figure 2, which is made of the same resin, and is not found in the foam board shown in Figure 3, which is a laminated film with a thick film attached to the foam board. This shows that the structure is different from that of a foam board. Furthermore, this feature provides surface hardness, compressive strength (surface), and suitability for shaping that cannot be achieved with the foam board shown in Figure 2, and compressive strength (surface) that cannot be achieved with the laminated foam board shown in Figure 3. It has the advantage of being able to demonstrate peeling resistance strength of the skin part and economical efficiency. A second feature of the foam board of the present invention is that the cells constituting the foam board having the first feature are made of a styrene copolymer resin containing at least one component of acrylic acid, methacrylic acid, and maleic anhydride. It is being formed. The reason for this is that the foam board of the present invention has heat resistance, flame resistance,
It is intended to have both food compatibility. For example, if the ingredients are changed to acrylamide, α-methylstyrene maleimide, etc., even if it is the same styrene-based copolymer resin, it will no longer have these characteristics. It is from. The circumstances around this are clearly shown in Table 1 of Examples and Comparative Example-1. According to the findings of the present inventors, an increase in the content of acrylic acid, methacrylic acid, and maleic anhydride may lead to a tendency to increase the heat resistance of the foam board, but conversely, the stress craze resistance of the foam board may be increased. Therefore, in such cases, if acrylic esters such as methyl acrylate and ethyl acrylate, which have relatively low melting points, or rubber substances are added in an amount of 10% or less, the resistance will decrease. This is effective because it can prevent deterioration in stress crazing properties. However, as a third feature of the foam of the present invention, even if the foam board satisfies the first and second features above, the styrene component of the resin composition is in the range of 75 to 95% by weight, and its Vikatsu softens. It must be made of a styrene copolymer resin with a temperature of 115°C or higher. The reason for this is to further perfect the heat resistance and food suitability of the molded product of the present invention, and further impart compressive strength, etc. Even if the ingredients meet the range of 75 to 95% by weight, the Vikatsu softening point is 115℃
If the styrene component is less than 115°C, the heat resistance will deteriorate, and even if the styrene component satisfies the conditions of 115°C or higher for the first and second characteristics, the suitability for food will deteriorate. This is because it has the disadvantage of The circumstances surrounding this are explained in the second example and comparative example 2.
clearly stated in the table. Next, the fourth feature of the present invention is the above-mentioned first,
Even if the foam board satisfies characteristics 2 and 3, the density of the foam board is 60 to 200 kg/ ^m3 , and the thickness (T) of the skin part described in the first characteristic is a foam board. Between the film thickness (t) of the bubble located inside, (T/
t) must satisfy the relationship of ≧2.5. The reason for this is to balance the insulation performance, sustainability of insulation performance, flame retardance, and surface hardness required of the foam board of the present invention to a practical level. In general, with foam boards, if the size of the bubbles and the thickness of the board are constant, reducing the density to improve the insulation performance will reduce the flame retardant properties and surface hardness, and increasing the bubble film thickness will reduce the flame retardant properties. Even if you increase the density, the surface hardness does not improve as much as the density increases, and if you try to improve the insulation performance by reducing the bubble diameter, the density will warp or bubbles will break, which will affect the insulation performance and its sustainability. There is a drawback that it may deteriorate. In the present invention, these difficulties in achieving mutual harmony are alleviated by providing a thick skin portion that substantially covers the surface portion of the foam board. According to the findings of the present inventors, the closer the shape of the bubble is to the surface layer and the flatter it is in the longitudinal direction of the cross section, the better the insulation performance. Too much is
Care must be taken as this may lead to a decrease in compressive strength and insulation performance. In the experiment, (T/t) is 10
It has been confirmed that a good molded product can be obtained even if the temperature is reduced to a certain extent. Furthermore, the fifth feature of the present invention is that even if the above features 1 to 4 are satisfied, the wall thickness of the foam board is 2.5%.
~7 mm, and the deflection coefficient (p/y) when the plate is pressed and bent according to JIS A-9511 must be 0.2 to 1.5. The reason for this is shown in the deep drawability, forming formability represented by the temperature range suitable for forming, and the dimensional change rate under heating load, which are necessary when forming the foam board of the present invention. This is to provide a practical level of heat resistance and falling weight impact resistance. In general, (p/y) varies depending on the thickness of the board, its density, etc., but the evaluation in the present invention (see Table 4) is based on the density and (T/t) being at approximately the same level. Therefore, the relationship between the wall thickness of the foam board and (p/y) here is based on the so-called foam board, which is a comprehensive consideration of the bubble shape, foam properties, bubble distribution, bubble film distribution, etc. inside the foam board. 1 showing the structural state of the internal bubbles
It can be said that there are two structural indicators. As detailed above, the foam board of the present invention satisfies all of the above-mentioned characteristics 1 to 5, and thus is a novel product that has various practical properties different from conventional styrene foam boards. This made it possible to create a foam board. The foam board of the present invention can be manufactured, for example, by careful preparation under special manufacturing conditions as described below. This will be explained with reference to the schematic diagram of the manufacturing apparatus shown in FIG.
It is supplied together with a general nucleating agent and a lubricant, and is heated and melted here. Next, a general organic blowing agent press-injected from the injection port 3 is mixed into the molten resin.
After being temperature controlled by the temperature regulator 4, it is extruded into a tube shape from an annular die 5 at a temperature of about 100 to 170°C into the atmosphere at room temperature and pressure. The tube-shaped parison 6 is inflated by the pressure inside the tube, and the deflator 7
Pinch roll 8 which is folded into a flat plate shape and has the function of picking up the parison and pinching the parison.
After that, the foam board 9 is formed. Further, 10 is a gas circulation mandrel for equalizing the pressure and controlling the temperature inside the bubble. At this time, special attention should be paid to the ratio of the diameter of the annular die to the maximum diameter of the inflation section (blow-up ratio), the opening angle of the deflator 7, and the balance with the temperature control inside the bubble. By that,
Although there are slight variations depending on the resin used, the blowing agent used, the target density, etc., in the experiments conducted by the present inventors, Γ blow-up ratio: 2.0 to 3.0 Γ deflator opening angle: 44 to 70 degrees Γ Blow temperature inside the bubble: 118 to 160 °C Γ It is necessary to select a combination within the range of a temperature difference between the inside and outside surfaces of the parison immediately before the clamping of 10 to 30 degrees.
This requirement results in the parison 6 being foamed immediately after extrusion and its outer surface being significantly cooled. In particular, this tendency is remarkable because the resin used in the present invention has a high melting point. On the other hand, as the outer surface of the parison is cooled, a hard skin is formed, but if the inner surface side is cooled too much, it will be fused and bonded to the integrated foam board 9 that will not peel off when the inner surface is cooled too much. Can not do it. However, if the temperature difference between the inner and outer surfaces of the parison is applied too quickly or to a large extent, the cell structure inside the parison will change and the structure will not satisfy the p/y relationship defined in the present invention. Therefore, the above conditions in the present invention include adding the cooling (and formation of bubble shape) accompanying the expansion in the biaxial direction to the external cooling with an appropriate degree of blow-up;
The idea is to balance the internal supercooling with temperature control (gradient) inside the bubble. At this time, the contact between the deflator and the bubble also contributes to cooling the outer surface of the parison, so in order to ensure an appropriate contact length with the bubble, the surface frictional resistance is reduced and the opening angle is adjusted to match the blow-up ratio. It is necessary to choose. The resins used in Examples and Comparative Examples are as follows.

[Table] Vikat softening point and (T/t) used in the present invention
The measurement method is based on the following method. ΓVikat Softening Point: ASTM-D-1525 Γ (T/t): Cut the foam board uniformly in the thickness direction, and measure the cross section of the foam board using a microscope or optical projector to determine the air bubbles located on the skin of the foam board. 10 points are randomly taken for each of the thickness of the skin part where the bubble membranes are connected and the thickness of the bubble membrane located in the center of the plate, and the average value of each is T and t. Take the ratio. Each evaluation item used in the present invention is based on the following evaluation method and evaluation scale. Heat Resistance Performance-1 Heat Resistance ΓEvaluation Method: Evaluated using as an index the lowest temperature at which a dimensional change of more than 1.0% occurs with respect to the initial dimension after 60 minutes of heating. Γ test piece: Dimensions: 300mm x 450mm Quantity: 2 pieces How to write the Γ mark line: Grip the test piece with the dimensions shown in Figure 5.
2 orthogonal at the center of the 30cm square on the opposite side of A1
Draw a line S1 on the book, and then draw a marked line S2 on this line about 50mm from the edge of the board. Measure the length of the marked line accurately to 0.05mm using a caliper. Γ constant temperature bath, hot air circulation constant temperature bath, measurement temperature (85℃±1℃, 90℃±1℃, 95℃±1
℃) Γ measurement method: Measure the distance between the gauge lines for the test piece in advance, then hang it in a thermostatic chamber by gripping part A1, heat it at each temperature for 60 minutes, and then leave it to cool while hanging. After cooling, measure the distance between the marked lines again, and measure the rate of change in width and length using the following formula. Di: E/l×100 Di: Dimensional change rate % E: Elongation or contraction due to heating (mm) l: Original distance between gauge lines (mm) Γ Evaluation scale

[Table] -2 Heat resistance (heating dimensional change rate) Γ evaluation method: -1 Heat resistance method,
Evaluated by determining the heating dimensional change rate Γ measurement conditions 90°C ± 1°C for 96 hours Γ test piece: -1 Same as heat resistant. Γ rating scale

[Table] -3 Heat resistance (heat dimensional change rate under load) Γ evaluation method: The heating dimensional change rate under load was evaluated using the L value determined by the method below. Γ test piece: length 450mm, width 50mm, thickness is sample size Γ measurement method: across one side of the test piece,
A load of 0.1 g/cm ³ was applied, the loaded side was placed facing downward, and placed on a support frame with a span length of 300 mm, heated for 96 hours in a hot air circulation constant temperature oven maintained at 90°C ± 1°C, and then brought to room temperature. After cooling, measure the amount of sagging Lmm at the center of the test piece, and calculate the sagging rate = L/300×100. Γ rating scale

[Table] Insulation performance-1 Insulation property Measurement of thermal conductivity Γ evaluation method: Based on ASTM C-518,
Evaluation scale in units of kcal/m・Hr・℃ and value at 0℃

[Table] -2 Thermal insulation properties (indicating the sustainability of insulation performance over time) Γ Evaluation method: Measure the thermal conductivity after forced water absorption, and evaluate by the ratio of the thermal conductivity before water absorption What I did. Γ Test method A foam board measuring 200 mm long, 200 mm wide, and the thickness of each sample is measured using the device shown in Figure 6. That is, in a container 11 equipped with a temperature controller 13 surrounded by a heat insulating material 12,
℃ hot water 14 is poured into the container, and the opening side of the container is closed with the foam board via the gasket 16. At this time, the foam board 15 is arranged so that there is a distance of about 30 mm between the lower surface of the foam plate 15 and the hot water surface in the container. Further, the upper surface of the foam board is cooled to 3°C by cooling water circulated from the circulation water ports 17 and 18.
Closely attached to. keep it like this
After leaving it for 60 days, the surface of the foam board was wiped gently with gauze, and the thermal conductivity λ' of this material was measured according to ASTM C518. The rate of change λ'/λ is determined and evaluated. Γ rating scale

[Table] Flame retardancy (referring to the magnitude of burning rate) Γ evaluation method: Measured according to ASTM-D-1692,
Evaluation in units of mm/mm Γ measurement method: Based on ASTM-D-1692 Γ evaluation scale

[Table] Molding performance - 1 Molding processability Γ Evaluation method In general, when heat forming or heating vacuum forming is performed, the depth of the molded product and the diameter of the molded product, or if the mouth shape of the molded product is rectangular, the short side of the molded product. This is an evaluation of the moldability of a molding material by measuring the length ratio and using the drawing ratio. Γ measurement method The aperture ratio is given by the following formula. Q=H/W Q: Drawing ratio H: Maximum depth of the molded product (mm) W: Diameter or length of one side of the mouth of the molded product, or length of the short side if the mouth of the molded product is rectangular Expressed by . Judgment of pass/fail is when there are no cracks, cracks, or surface roughness on the surface of the molded product due to molding, and the ratio of the inner dimension (a) of the concave mold of the molding die to the outer dimension (b) of the molded product. The moldable range is defined as the case where (a/b) is 0.9 or more, and the ratio (c/d) between the outside dimension (c) of the convex mold of the mold and the inside dimension (d) of the molded product is also 0.9 or more. do. Γ rating scale

[Table] -2 Molding processability (heat molding processability of foam board) Γ Evaluation method: Measure the maximum molding temperature range at the optimum temperature during heat processing, and evaluate the heat molding process of the foam board depending on whether the molding temperature range is large or small. Gender evaluation. Γ measurement device 560mm x 400mm area with 12cm intervals above and below
Heating device with 5.4KW infrastyle heaters installed on both top and bottom sides and 440mm x 330mm depth
Press-type thermoforming machine equipped with a small model wooden mold with 50mm corners and 60R. Γ Test method After heating both sides of the foam board, remove the heater, leave it for 5 seconds, and then mold the product. The temperature conditions that allow the longest heating time are selected for each test foam board, and the evaluation is made based on the length of the heating time. Γ rating scale

[Table] Surface hardness Γ evaluation method: Measured by JIS K6301C type and evaluated surface hardness. Γ rating scale

[Table] Compressive strength Γ evaluation method: Load required to compress 10% of the thickness using the ASTM-D-1621 method, i.e.
The pressure resistance characteristics were evaluated by measuring 10% compressive strength. Γ rating scale

[Table] Falling weight impact resistance Γ Evaluation method: Evaluated according to the falling weight impact test method of ASTM-D-1709-75. A missile-shaped weight with a diameter of 38 mm is dropped from a height of 66 cm, and the load is increased or decreased by 40 g.
The weight was dropped 20 times and calculated according to the ASTM calculation method. Γ rating scale

[Table] Suitability for food -1 Suitability for food (amount of volatile components) Γ Evaluation method: The remaining amount of volatile components and comonomer of the resin used in the material test in accordance with the self-regulation of the Polyolefin Hygiene Council, and the total amount of volatile components Quantitated and evaluated by gas chromatography. Γ rating scale

[Table] -2 Food suitability (PH value) Γ evaluation method After crushing 1 g of foam board and boiling it in 50 ml of distilled water for 2 hours, filter the sample and cool the filtrate. PH was measured and evaluated according to "Measurement Method". Γ rating scale

[Table] Examples/Comparative Examples 1 Using the same equipment as in Fig. 4, resin numbers B, D,
Foamed boards were created for each of the resins E, F, J, K, L, and M (the above eight types). At this time, the aim of the foam board obtained was to have a density of 140% Kg/m ³ and (T/
t) = 4.0, foam board thickness 4 mm, (p/y) = 0.5,
In order to get as close to this as possible, the main manufacturing conditions were set as follows. However, talc was used as a nucleating agent, barium stearate was used as a lubricant, and dichlorodifluoromethane was used as a blowing agent (unless otherwise specified, the same applies to each subsequent example).

[Table] The obtained foam boards were numbered sequentially from 1 to 8 and evaluated for heat resistance, flame retardancy, and suitability for food using the evaluation method described in the text, and the results are summarized in Table 1. . According to the results in Table 1, the components of the styrene copolymer resin constituting the foam board of the present invention must be selected from acrylic acid, methacrylic acid, and maleic anhydride. I understand.

[Table] Example/Comparative Example 2 Example/Comparative Example 2 Except that the resin used was changed to A, C, G, H, and I (5 types in total) and the main manufacturing conditions were as follows. A foam board was created using the same conditions and method as in Comparative Example-1.

[Table] The obtained foam boards are numbered 9 to 13 in order, and foam board No. 1 from which Example/Comparative Example-1 was obtained;
Along with 3 and 4, heat resistance,
Compressive strength and suitability for food were evaluated and the results are summarized in Table 2. According to the results in Table 2, even if the styrene copolymer resin constituting the foamed board of the present invention contains acrylic acid, methacrylic acid, or maleic anhydride, the styrene component The percentage is
It is understood that the content must be 75 to 95% by weight, and even within that range, it must have a Vicatto softening point of 115°C or higher.

[Table] Example/Comparative Example 3 Using the same conditions and method as Example/Comparative Example-1, except that the resin used was fixed to symbol B and the main manufacturing conditions were as follows,
Various foam boards were created.

[Table] At this time, adjust the thickness of the foam board to the target of 4mm as much as possible,
Since (p/y) was set to be close to the value of 0.4,
The density of the resulting foam board varied widely. The obtained molded bodies were numbered 14, 15 and 18-22. In order to reproduce and confirm a part of the above method, the resins used were changed to those with numbers E and F, and the foam boards obtained were numbered 16 and 17. The No. 1 foam board obtained in Example/Comparative Example-1 was added to the nine types of foam boards obtained, and each foam board was evaluated for heat insulation, flame retardancy, heat insulation, and The surface hardness was evaluated and the results are summarized in Table 3. The results in Table 3 show that even if the foam of the present invention is made of a resin that satisfies the resin composition range and Picato softening point referred to in the present invention, it does not meet the evaluation items required for the molded plate of the present invention. It can be seen that a molded plate that satisfies the standard must have a density in the range of 60 to 200 kg/m ³ and a structure in which (T/t) shows a value of at least 2.5. .

【table】

[Table] Example/Comparative Example 4 23, 24, 25, as well as
They were numbered 27, 28, and 29.

[Table] For confirmation, molded bodies using resins with D and F signals are numbered 26, 30, and 31. In this case, the thickness and (p/y) of the foam board were not uniform and varied. Molding workability and moldability were evaluated using the evaluation methods described in the text for 11 types of foamed boards, including the 9 types of foamed boards obtained and foamed boards No. 1 and 4 obtained in Example/Comparative Example-1. , heat resistance and falling weight impact resistance were evaluated.
The results are summarized in Table 4. According to the results in Table 4, even if the foam board of the present invention satisfies each range of component composition, Picato softening point, density, and (T/t) as defined in the present invention,
The structure of the foamed board that satisfies the evaluation items that the foamed board of the present invention should have is a foamed board with a thickness in the range of 2.5 to 7 mm and a cell structure expressed by p/y in the range of 0.2 to 1.5. I know it has to be something.

[Table] Example/Comparative Example 5 The foamed board of the present invention has all the evaluations specified in the present invention, and it is clear how this board is positioned compared to the current commercially available products of the same type. In order to achieve this, the following foamed boards were evaluated using the various evaluation methods described in the text. Γ Foam board of the present invention (representative) No. 1, No. 4 Γ Commercial product (representative) Symbol Product name Main use Manufacturer W Utsudrak B For welding boxes Asahi Dow X 〃 〃 For building materials 〃 Y - For welding boxes Y The results are shown in Table 5. According to the results in Table 5, the foam board of the present invention satisfies practical values in all evaluation items, and is particularly excellent in heat resistance, heat insulation, formability, and external stress resistance. It can be seen that this is a new molded product with characteristics not found in current commercially available products.

【table】

[Table] Comparative example 6 The resin used was of symbol E, the die temperature was 135
℃, blow ratio to 3.5, deflator opening angle to
Example/Comparative Example-1 except for each change to 42 degrees
A foam board (No. 32) was obtained by repeating the same type of experiment. The skin on the surface of this foam board was extremely thin and fell below the value of (T/t)≧2.5 as defined in the present invention. Next, a sheet of approximately 0.11 mm (stretched approximately 3 times in both the vertical and horizontal directions) was melt-extruded from product name Dylarc #250 (manufactured by Alco, USA (maleic anhydride/rubber/styrene copolymer)). The foam plate prepared in advance was thermally bonded to the surface of the foam No. 32 at a temperature of about 120°C to obtain a foam board (Z) with a skin. Fig. 3 shows an enlarged cross-sectional photograph of the foam board (Z). As is clear from FIG. 3, although the foam board (Z) is conceptually the same as the skinned foam board of the present invention, its internal cell structure is different, and at least the surface layer of the foam board is different. The bubble membranes of the bubbles located in the area are connected and do not form the skin.
Moreover, this structural difference is, for example, when comparing the compressive strength and peel strength of the skin part, the compressive strength is about 30% lower and the peel strength is about 60% lower than that of the foam board of the present invention. It is expressed as a value. By satisfying the above-mentioned structural requirements, the present invention has heat resistance around 90°C and thermal conductivity at 0°C.
Insulation properties of 0.03 to 0.04kcal/m・Hr・℃ and its durability, flame retardant properties, formability that allows press processing into desired shapes, easy deformation by external force, surface hardness that does not break, compressive strength It has the following advantages: , impact resistance, and suitability for foods that do not transfer chemical substances into foods, and can be easily provided by the foam extrusion method. Therefore, even when this foam board is used as a slate lining material for the interior of a vehicle, etc., and the surface temperature reaches nearly 70℃, the foam board will not deform or change dimensions, and will maintain sufficient strength. It exhibits heat insulating properties, and even if it is used for heat sterilization on, for example, kamaboko board or tableware, it will not deform and become unusable, and it will not transfer chemical substances into food. Even when used as a container for cooking food in a microwave, the container can be taken out as is without causing burns, and its practicality is extremely wide, making it an excellent invention that will play a major role in industry.

[Brief explanation of the drawing]

FIG. 1 is an enlarged photograph of a cross-sectional portion of the foamed board of the present invention.
FIGS. 2 and 3 are enlarged photographs of cross-sectional parts of comparative products. FIG. 4 is a schematic side view of an apparatus for manufacturing a foam board of the present invention, FIG. 5 is a diagram showing the dimensions of a test piece, and FIG. 6 is a side sectional view of a thermal conductivity measuring apparatus.

Claims (1)

[Claims] 1. A styrene component containing at least one component of acrylic acid, methacrylic acid, and maleic anhydride is 75
~95% by weight of styrenic copolymer resin with a softening point of 115°C or higher, density 60
~200Kg/m ³ and a wall thickness of 2.5 to 7 mm, the board has a thickness ( T/
t) ≧2.5, and the deflection coefficient (p/y) when the plate is pressed and bent according to JIS A-9511 is 1.5≧(p/y). )
≧0.2 However, the deflection coefficient (p/y) is the coefficient at the part where the relationship between the load (p) and the deflection amount (y) is substantially linear. It is measured under the following conditions and calculated using the following formula. (p/y)=E・4bh ³ /l ³ p; Load (Kg) l; Span distance (cm) [20cm was adopted] b; Width of foam board piece (cm) [7.5cm was adopted] h; Foaming Thickness of plate piece (cm) [according to each measurement] E: Flexural modulus (Kg/cm ² ) [according to JIS A-9511 polystyrene foam] y: Amount of deflection (cm)