JP6590611B2 - Polystyrene resin sheet laminated foam - Google Patents

Description

  The present invention relates to a polystyrene resin plate-like laminated foam.

  Conventionally, polystyrene-based resin foam boards (hereinafter also referred to simply as foam boards) are white due to their cell structure, are lightweight, and have excellent flatness, so photos and posters for exhibition are pasted. It is used as a display panel that is used by printing on the surface of the foam plate itself, and in recent years, it is also used as a fixed planting panel for hydroponics.

  In these applications, it may be required that light is not transmitted from one side of the panel to the other side. In order to suppress the transmission of light, a method of coloring the foam plate constituting the panel to black or the like can be considered. However, in this case, it becomes difficult to print on the panel surface, and when the poster is pasted, the color of the foam plate appears through the poster and the color tone is different from the original one. There was a problem of becoming something. In addition, a fixed planting panel for hydroponics is required to reflect light on its surface, but the black foam plate has a problem that it absorbs light and a sufficient amount of reflection cannot be obtained. .

  As a method for solving these problems, a colored resin material is used as an inner layer, and an uncolored resin material is used as an outer layer, and each is introduced into a molding machine, and a colored foam layer is formed by coextrusion. A cylindrical laminate with an uncolored foam layer laminated on the outside is formed, and the cylindrical laminate is crushed by passing it between rolls, etc., and an uncolored foam layer is disposed on both sides of the colored foam layer. A method for producing a provided polystyrene-based resin sheet laminated foam has been proposed (see, for example, Patent Document 1).

Patent No. 3098376

  However, the plate-like laminated foam obtained by the above method has a sufficient light-shielding property by coloring the inner layer black, but the black inner layer appears on the surface through the outer white layer, There was a problem that the whiteness inherent to the foamed plate was impaired.

  The present invention has been made in view of the above-mentioned conventional problems. In a polystyrene resin plate-like laminated foam having a white polystyrene resin foam layer on both sides of a black polystyrene resin foam layer produced by coextrusion. The black foam layer of the inner layer provides sufficient light-shielding properties, and the specific white polystyrene resin foam layer of the outer layer has the same appearance as a conventional non-colored polystyrene resin foam, with a low manufacturing cost. It is an object of the present invention to provide a suppressed polystyrene-based resin plate-like laminated foam.

The present invention provides the following polystyrene-based resin plate-like laminated foam .
<1> A plate-like laminated foam having an apparent density of 40 to 150 kg / m ³ , having a white polystyrene resin foam layer laminated and adhered by coextrusion on both sides of a black polystyrene resin foam layer, the white polystyrene resin The foamed layer contains 1 to 12% by mass of a white pigment with respect to 100% by mass of the resin composition constituting the foamed layer , the white pigment is titanium oxide, and the basis weight per one side of the white polystyrene resin foamed layer. Is 15 g / m ² or more, the ratio of the basis weight per side of the white polystyrene resin foam layer to the total basis weight of the foam is 0.2 or less, respectively, and the average of the thickness direction of the white polystyrene resin foam layer is cell diameter is not more than 0.25mm, the thickness per one side of the white polystyrene resin foam layer is less than 3mm, respectively, JIS Z8781-4: 2013 Brute der CIE1976 lightness index L ^* is 70 or more surfaces of the plate-like laminated foam is, plate-like laminated foam Ru panels der the panel or hydroponics for a display, a polystyrene resin plate laminated foam.
<2> The polystyrene resin plate-like laminated foam according to <1>, wherein the thickness of the black polystyrene resin foam layer is 1 mm or more .
<3> The average cell diameter in the thickness direction of the black polystyrene-based resin foam layer is 0.15 to 0.70 mm, and is larger than the average cell diameter in the thickness direction of the white polystyrene-based resin foam layer , <1> or <2> The polystyrene-based resin plate-like laminated foam according to <2>.
<4> The apparent density of white polystyrene resin foam layer is 30~150kg / ^{m 3,} a polystyrene resin plate laminate foam according to any one of the <3><1>.
<5> The black polystyrene-based resin foam layer contains a black colorant, and the blending amount of the black colorant is 0.1 to 5% by mass with respect to 100% by mass of the resin composition constituting the foam layer , <1 > To <4>.
<6> The polystyrene resin plate-like laminated foam according to any one of <1> to <5>, wherein the total basis weight of the foam is 180 to 1800 g / m ² .

  According to the present invention, in a polystyrene resin plate-like laminated foam having white polystyrene resin foam layers on both sides of a black polystyrene resin foam layer produced by coextrusion, the inner black polystyrene resin foam layer is more sufficient. A polystyrene resin plate-like laminated foam that has light-shielding properties and has the same appearance as a conventional non-colored polystyrene resin foam with a specific white polystyrene resin foam layer on the outer layer, and has a low production cost Can be provided.

It is a schematic sectional drawing which shows the polystyrene-type resin plate-shaped laminated foam of this invention. It is the schematic of the extruder used for manufacture of the polystyrene-type resin plate-shaped laminated foam of this invention.

  Hereinafter, the form for implementing this invention is given and the polystyrene-type resin plate-like laminated foam of this invention is demonstrated in detail. FIG. 1 shows a schematic cross-sectional view of a polystyrene resin plate-like laminated foam of the present invention.

  The polystyrene-based resin plate-like laminated foam 1 of the present invention is a white polystyrene-based resin foam layer (hereinafter referred to as a black polystyrene resin foam layer (hereinafter simply referred to as a black foam layer) 2) laminated and adhered by coextrusion on both sides. , Which is simply referred to as a white foam layer).

<Black foam layer>
The black foam layer 2 constituting the polystyrene resin plate-like laminated foam 1 is composed of a black foam layer 2 containing a polystyrene resin, a physical foaming agent, and if necessary, a black colorant, a bubble adjusting agent and other additives. The resin melt to be formed is formed by extrusion foaming.

(Polystyrene resin)
The polystyrene resin can be used without particular limitation as long as it is a polystyrene resin usually used for a polystyrene resin foamed board. For example, polystyrene (GPPS), high impact polystyrene (HIPS), styrene-acrylonitrile copolymer Polymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-methyl methacrylate copolymer, styrene-maleic anhydride copolymer, polystyrene-polyphenylene ether copolymer, styrene-acrylonitrile-butadiene copolymer A polymer or the like can be used. Moreover, these may be used individually by 1 type and may be used in combination of 2 or more types.

  For the black foam layer, as the above polystyrene resin, a new polystyrene resin (virgin polystyrene resin) that has never been used for molding, or an uncolored polystyrene regenerated from an uncolored polystyrene resin foam or the like. Colored polystyrene resin (colored recycled polystyrene resin) regenerated from colored polystyrene resin foam or polystyrene resin foam laminated with colored film, as well as resin based on color (colorless recycled polystyrene resin), What used these together can be used.

  Moreover, in this invention, resin other than the said polystyrene-type resin can be mixed and used. Examples of these resins include polyethylene resins such as polyethylene terephthalate resins, polyphenylene ether resins, propylene homopolymers and ethylene-propylene copolymers, polyethylene resins such as high-density polyethylene and low-density polyethylene, and styrene-conjugates. Those containing a polymer such as a diene block copolymer or a thermoplastic elastomer such as a hydrogenated product thereof, or a rubber such as ethylene-propylene rubber or butadiene rubber can be used.

(Black colorant)
The black foam layer preferably contains a black colorant. As a result, black color appears stably. The black colorant is not particularly limited as long as it is a black and dark colorant. For example, an inorganic pigment, an organic pigment or a dye adjusted to a dark color can be used.

  Among these colorants, inorganic pigments are preferable. Examples of inorganic pigments include carbon black pigments such as carbon black and graphite, and oxide black pigments such as iron oxide and copper-chromium-manganese composite oxides. Can be mentioned. Among these, carbon black can be suitably used.

  These colorants may be used alone or in combination of two or more. Further, when two or more kinds are used in combination, it is desirable to use carbon black together because a certain light shielding property can be obtained.

  In consideration of reliable light-shielding properties, the amount of the black colorant added to the black foam layer may be the resin composition constituting the black foam layer 2 (addition of resin components and colorants excluding the foam agent). The range of 0.1 to 5% by mass is preferable with respect to 100% by mass, and the range of 0.1 to 3% by mass is more preferable. A certain light-shielding property can be acquired by making the compounding quantity of a black coloring agent into said range.

(Physical foaming agent)
Examples of the physical foaming agent include aliphatic hydrocarbons having 2 to 6 carbon atoms such as ethane, propane, normal butane, isobutane, normal pentane, isopentane, isohexane, cyclohexane, methyl chloride, ethyl chloride, 1,1,1. , 2-tetrafluoroethane, 1,1-difluoroethane, etc., halogenated aliphatic hydrocarbons having 1 to 4 carbon atoms, methanol, ethanol, propanol, butanol, etc., aliphatic alcohols, dimethyl ether, Organic physical foaming agents such as aliphatic ethers having 2 to 8 carbon atoms such as diethyl ether and dipropyl ether, or inorganic physical foaming agents such as nitrogen, carbon dioxide, and water can be used.

  These physical foaming agents may be used individually by 1 type, and may use 2 or more types together. Moreover, what has isobutane, normal butane, or these mixtures as a main component can be used suitably from a viewpoint of compatibility with a polystyrene-type resin and foaming efficiency.

  The amount of the physical foaming agent added can be appropriately adjusted according to the average cell diameter of the black foam layer 2 defined in the present invention, but usually 100 parts by mass of the resin composition for forming the black foam layer 2 On the other hand, the range of 2-12 mass parts is preferable, and the range of 3-9 mass parts is more preferable. In addition to the above physical foaming agent, a chemical foaming agent may be used in combination as the foaming agent.

(Bubble conditioner)
As the bubble adjusting agent, either an organic type or an inorganic type can be used. Examples of the inorganic air conditioner include metal borates such as zinc borate, magnesium borate, borax, sodium chloride, aluminum hydroxide, talc, zeolite, silica, calcium carbonate, sodium bicarbonate and the like. .

  Examples of the organic foam regulator include sodium phosphate-2,2-methylenebis (4,6-tert-butylphenyl), sodium benzoate, calcium benzoate, aluminum benzoate, and sodium stearate. Can do. A combination of a chemical foaming agent such as citric acid and sodium bicarbonate or an alkali salt of citric acid and sodium bicarbonate can also be used. These bubble regulators may be used alone or in combination of two or more.

  The addition amount of the cell regulator is not particularly limited, but is usually preferably in the range of 0.1 to 0.5% by mass with respect to 100% by mass of the resin composition constituting the black foam layer 2. The range of 0.1-0.3 mass% is more preferable.

(Other additives)
As a material component for molding the black foam layer 2, various additives can be added in addition to the above components as long as the object of the present invention is not impaired. Examples of the additives include antioxidants, heat stabilizers, weathering agents, ultraviolet absorbers, flame retardants, inorganic fillers, antibacterial agents, and the like.

<White foam layer>
The white foam layer 3 constituting the polystyrene resin plate-like laminated foam 1 is composed of a white foam layer 3 containing a polystyrene resin, a white colorant, a physical foaming agent, and a bubble regulator and other additives as necessary. The resin melt to be formed is formed by extrusion foaming.

(Polystyrene resin)
As the polystyrene resin, those similar to the above styrene resin can be used.

(White pigment)
The white pigment is not particularly limited as long as a specific brightness index can be obtained. For example, a white inorganic pigment or an organic pigment can be used.

Among these colorants, inorganic pigments are preferable, and examples of inorganic pigments include titanium oxide (TiO ₂ ), lead white, zinc white, and barium sulfate. Among these, it is desirable to use titanium oxide from the viewpoint of obtaining a high brightness index.
Moreover, these white pigments may be used individually by 1 type, and 2 or more types may be mixed and used for them.

  The amount of the white pigment added to the foamed plate is 1 with respect to 100% by mass of the resin composition constituting the white foamed layer 3 (a mixture of the resin component and an additive such as a white pigment excluding the foaming agent). It is -12 mass%, Preferably it is the range of 2-6 mass%. When the blending amount of the white pigment is less than 1% by mass, the whiteness becomes insufficient, the black foam layer 2 appears to be transmitted, and the brightness index defined in the present invention may not be obtained. In addition, when the amount is more than 12% by mass, the blended white pigment itself serves as a core material, the surface texture becomes too fine, a corrugated pattern called corrugate occurs, and the flatness of the foam plate is impaired. There is.

(Physical foaming agent)
As a physical foaming agent, the same foaming agent as used when forming the black foamed layer 2 can be used.

  The amount of the physical foaming agent added can be appropriately adjusted according to the average cell diameter of the white foam layer 3 defined in the present invention, the desired apparent density, and the like, but usually for forming the white foam layer 3. The range of 2-6 mass parts is preferable with respect to 100 mass parts of resin compositions, and the range of 3-5 mass parts is more preferable.

(Bubble conditioner)
As a bubble regulator, the thing similar to the bubble regulator used when forming the black foaming layer 2 can be used.

  The addition amount of the cell regulator is not particularly limited, but is usually in the range of 0.3 to 2.0% by mass with respect to 100% by mass of the resin composition for forming the white foam layer 3. The range of 0.5 to 1.5% by mass is more preferable.

(Other additives)
As a material component for molding the white foam layer, various additives can be added within the range not impairing the object of the present invention in addition to the above components. Examples of the additive include antioxidants, heat stabilizers, weathering agents, ultraviolet absorbers, flame retardants, inorganic fillers, algaeproofing agents, and antibacterial agents.

(Manufacturing method of polystyrene resin sheet laminated foam)
Hereinafter, an embodiment of a method for producing a polystyrene resin plate-like laminated foam of the present invention will be described. The schematic of the extruder used for manufacture of the polystyrene-type resin plate-shaped laminated foam of this invention in FIG. 2 is shown.

  The manufacturing method of the polystyrene-type resin plate-like laminated foam 1 of the present invention is as follows. First, a polystyrene-type resin 4 which is a material for forming the black foam layer 2 and other additives (black colorant) added as necessary. 5, bubble regulator 6 and the like) are supplied to the first extruder 7 and heated and kneaded, the physical foaming agent 8 is press-fitted and further kneaded, adjusted to an appropriate foaming temperature, and the resin foam 9 for forming a black foam layer is formed. And

  At the same time, polystyrene resin 10, white pigment 11, and other additives that are added as necessary (such as bubble regulator 12), which are materials for forming white foam layer 3, are supplied to second extruder 13. Then, the mixture is heated and kneaded, the physical foaming agent 14 is press-fitted and further kneaded, adjusted to an appropriate foaming temperature, and a white foamed layer forming resin melt 15 is obtained.

  The proper foaming temperatures of the black foam layer-forming resin melt 9 and the white foam layer-forming resin melt 15 mean temperatures that exhibit optimum viscoelasticity for foaming. The appropriate foaming temperature is appropriately determined depending on the type of polystyrene resin, melt viscosity, type of foaming agent, and amount added, but usually a range of about 120 to 170 ° C. is considered.

  Next, the discharge amount of the resin foam 9 for forming the black foam layer and the resin melt 15 for forming the white foam layer is controlled and introduced into the annular die 16, and the black foam layer forming resin is melted in the annular die 16. After the product 9 and the white foam layer forming resin melt 15 are joined and laminated, coextrusion is performed to produce a cylindrical laminated foam in which the white foam layer 3 is laminated and bonded to the outer peripheral surface of the black foam layer 2. Then, the tubular laminated foam is passed through the pinch roll 17 while being taken, and the inner surfaces of the black foam layer 2 on the inner side of the tubular laminated foam are fused and bonded together. Thus, the polystyrene resin plate-like laminated foam 1 of the present invention in which the white foam layer 3 is laminated and adhered can be obtained. The obtained polystyrene-based resin plate-like laminated foam 1 is cut into dimensions according to the application to obtain a product.

  In addition, the various apparatuses, such as a die | dye and an extruder which are used in manufacture of the said polystyrene-type resin plate-like laminated foam 1, can use suitably the well-known thing conventionally used in the field of extrusion foaming.

  In addition, by cutting the cylindrical laminated foam along the extrusion direction to obtain a sheet-like laminated foam, the black foam layers 2 of the two sheet-like laminated foams are heat-sealed and bonded together The polystyrene resin plate-like laminated foam 1 of the present invention can also be obtained.

In the polystyrene-based resin plate-like laminated foam 1 of the present invention, the surface brightness index L ^* , the apparent density of the polystyrene-based resin plate-like laminated foam 1, the basis weight per side of the white foam layer 3, and the white foam layer 3 The average cell diameter in the thickness direction, the thickness and apparent density per side of the white foam layer 3, the thickness of the black foam layer 2, and the average cell diameter in the thickness direction of the black foam layer 2 are defined. Each rule of the present invention will be described in detail below.

(Surface brightness index L ^* )
In the polystyrene resin plate-like laminated foam 1 of the present invention, the surface brightness index L ^* is 70 or more, preferably 80 or more, more preferably 85 or more. When the lightness index L ^* is in the above range, the foam plate has the same appearance as a conventional single-layer foam plate (uncolored). From this point of view, the upper limit is not particularly limited, but it is preferably about 90 because the lightness index L ^{* of} a normal single-layer foamed plate is about 85-90.

In addition, the lightness index L ^* in the present invention means the CIE1976 lightness index L ^* of the surface of the plate-like laminated foam based on JIS Z8781-4: 2013.

(Apparent density, overall thickness, overall basis weight of polystyrene-based resin sheet laminated foam 1)
The apparent density of the polystyrene resin plate-like laminated foam 1 is in the range of 40 to 150 kg / m ³ , preferably 40 to 100 kg / m ³ , more preferably 40 to 70 kg / m ³ . When the apparent density is within the above range, a polystyrene resin plate-like laminated foam having an excellent balance between lightness and mechanical strength can be obtained. Similarly, the total thickness of the polystyrene resin plate-like laminated foam 1 is preferably in the range of 3 to 30 mm, more preferably 5 to 25 mm, and the overall basis weight is preferably 180 to 1800 g / m ² , more preferably. Is in the range of 300-1500 g / m ² .

(Basis weight per side of white foam layer)
The basis weight per side of the white foam layer 3 in the polystyrene-based resin plate-like laminated foam 1 is 15 g / m ² or more, preferably 20 g / m ² or more, more preferably 60 g / m ² or more. By setting the basis weight per one side of the white foam layer 3 within the above range, the surface appearance can be made beautiful and a sufficient brightness index can be obtained. If the ratio of the white foam layer is too high, the mechanical strength such as the compressive strength of the foam board may be insufficient depending on the application, so the ratio of the basis weight per side of the white foam layer to the overall basis weight of the foam board Is preferably 0.2 or less, and more preferably 0.1 or less.

(Average cell diameter in the thickness direction of the white foam layer)
The average cell diameter in the thickness direction of the white foam layer 3 is 0.25 mm or less, preferably 0.20 mm or less, more preferably 0.15 mm or less, and still more preferably 0.10 mm or less. By setting the average cell diameter in the thickness direction within the above range, a sufficient brightness index can be obtained. From the viewpoint of production stability and mechanical strength of the foamed plate, the lower limit of the average cell diameter is preferably about 0.05 mm, more preferably 0.07 mm.

  In addition, the average bubble diameter of the thickness direction of the white foam layer 3 is calculated | required as follows. A cross section perpendicular to the extruding direction is photographed with a microscope at 10 positions at equal intervals over the entire width of the white foam layer 3, and the thickness t of the white foam layer 3 is measured for each cross-sectional photograph. Next, a straight line 1 is drawn in the thickness direction of each cross-sectional photograph, and the number n of all bubbles in the white foam layer 3 intersecting with the straight line 1 is counted. The bubble diameter (t / n) is calculated for each cross-sectional photograph from t and n thus obtained, and the arithmetic average value of 10 (t / n) is calculated as the average bubble diameter in the thickness direction of the white foam layer 3. And

(Thickness and apparent density per side of white foam layer)
The thickness and apparent density per one side of the white foam layer 3 are particularly limited as long as the above-mentioned basis weight per one side and the average cell diameter in the thickness direction are satisfied, and the surface brightness index L ^* is within the above range. Although it is not intended, the upper limit of the thickness per one side is preferably 3 mm, more preferably 2 mm, and the lower limit thereof is preferably 0.1 mm, more preferably 0.2 mm. . The apparent density is considered to be in the range of ^{30 to} 150 kg / m ³ , preferably 30 to 80 kg / m ³ .

(Thickness of black foam layer)
The thickness of the black foam layer 2 in the polystyrene-based resin plate-like laminated foam 1 can be appropriately set according to the application on the condition that sufficient light-shielding property is obtained, and is not particularly limited. A range of 1 mm or more, preferably 3 mm or more is considered.

(Average cell diameter in the thickness direction of the black foam layer)
The average cell diameter in the thickness direction of the black foam layer 2 is in the range of 0.15 to 0.70 mm, preferably 0.20 to 0.60 mm, and is larger than the average cell diameter in the thickness direction of the white foam layer 3. It is desirable to have a large average bubble diameter. By setting the average cell diameter in the thickness direction of the black foam layer 2 as the above condition, reliable light shielding properties can be obtained and high mechanical strength can be obtained. The average cell diameter in the thickness direction of the black foam layer can be determined in the same manner as the average cell diameter in the thickness direction of the white foam layer.

  Hereinafter, the polystyrene resin plate-like laminated foam of the present invention will be specifically described with reference to examples. However, the present invention is not limited to the examples.

  As a manufacturing apparatus, as a black foam layer forming extruder (first extruder), a tandem type extruder composed of an extruder having a barrel inner diameter of 115 mm and an extruder having a barrel inner diameter of 150 mm connected to the extruder is used. A co-extrusion annular die (lip diameter: 180 mm) is attached to the outlet of the extruder, and a white foam layer forming extruder (second extruder) is attached to the co-extrusion annular die as an extruder with a barrel inner diameter of 65 mm. A coupled coextrusion device was used.

In addition, the following were used for each material for black foam layers and white foam layers introduced into the manufacturing apparatus.
Polystyrene resin polystyrene (PS): Toyo Styrene HRM12N, MFR (200 ° C., load 5 kg): 5.4 g / 10 min recycled polystyrene (RPS): miscellaneous color recovery polystyrene resin, MFR (200 ° C., load 5 kg): 8 0.7 g / 10 min Physical blowing agent: Industrial butane (isobutane: normal butane = 30:70)
White pigment: titanium oxide (white pigment MB, titanium oxide content 60%, manufactured by Resino Color)
Black colorant: Carbon black for coloring (Black pigment MB manufactured by Dainichi Seika Co., Ltd., 48% carbon black content)
Bubble regulator: Talc (Bubble regulator MB, manufactured by Dainichi Seika Co., Ltd., talc content 35%)

  About Examples 1-7 and Comparative Examples 1-5, the polystyrene-type resin for black foam layer formation, a black coloring agent, and a bubble regulator are supplied to a 1st extruder with the compounding quantity shown in Table 1 and Table 2, Heating, melting, and kneading were performed, and the physical foaming agent in the amount shown in Tables 1 and 2 was poured into the resulting resin melt for forming a black foam layer. At the same time, a polystyrene-based resin for forming a white foam layer, a white pigment, and a cell regulator are supplied to the second extruder in the blending amounts shown in Tables 1 and 2, and heated, melted and kneaded. The amount of physical foaming agent shown in Table 1 and Table 2 was injected to obtain a white foamed layer forming resin melt.

  And the discharge amount of each resin melt is adjusted so that the ratio of the basis weight of each layer becomes the value shown in Table 1 and Table 2, and in the annular die for coextrusion, the resin melt for forming the black foam layer and the white The foamed layer forming resin melt is merged, the white foamed layer forming resin melt is laminated on the outer peripheral surface of the black foamed layer forming resin melt, and then co-extruded into a cylindrical shape. Formed. Examples 1 to 7 were formed by sandwiching the cylindrical foam with pinch rolls, fusing and bonding the inner surfaces of the black foam layers, and cutting to a desired width and length (630 mm × 1960 mm). And the polystyrene-type resin plate-shaped laminated foam of Comparative Examples 1-5 was obtained.

  About the obtained polystyrene-type resin plate-like laminated foam of Examples 1-7 and Comparative Examples 1-5, white foam layer thickness, white layer ratio, black foam layer thickness, overall thickness, white layer basis weight, overall basis weight The white layer apparent density, the overall apparent density, the white layer average cell diameter in the thickness direction, and the black foam layer average cell diameter were measured by the following methods. The results are shown in Tables 1 and 2.

(Thickness)
From a randomly selected portion of the polystyrene-based resin plate-like laminated foam 1 (630 mm × 1960 mm), cut into a length of 100 mm in the extrusion direction over the entire width in the width direction, and a test piece having a width direction of 630 mm and an extrusion direction of 100 mm; did. The test piece was further divided into 10 equal parts in the width direction, and the thicknesses of the white foam layer, the black foam layer, and the total thickness were measured at the center in the width direction of each test piece based on the cross-sectional photograph. . The arithmetic average value of the thickness at each measurement point for 10 equal parts was defined as each thickness. In addition, the white foam layer thickness in a table | surface is the thickness per one side calculated | required by arithmetically averaging the thickness of two white foam layers.

(Basis weight)
Measure the mass of the test piece of 10 equal parts, divide the total of each mass by the total area of the test piece (630 mm × 100 mm), and further convert the unit to g / m ² , did.
Further, only the white foam layer is cut out from the test piece, the mass of the part is measured, the total of each mass is divided by the total area of the test piece (630 mm × 100 mm), and further divided by 2. The basis weight per one side of the white foam layer was calculated in terms of g / m ² .

(Apparent density)
The total basis weight was divided by the total thickness, and the unit was converted to g / cm ³ to obtain the total apparent density. Further, the basis weight per one side of the white foam layer was divided by the thickness per one side and further converted to g / cm ³ to obtain the apparent density of the white foam layer.

(Average cell diameter in the thickness direction)
The number of bubbles (n) in the thickness direction of the portion where the thickness (t) of the black foam layer and the white foam layer was measured for each of the 10 test pieces was counted, and the thickness (t) and thickness (t) were measured. The bubble diameter (t / n) is determined from the number of bubbles in the thickness direction corresponding to (n), and the arithmetic average value of the 10 bubble diameters (t / n) is calculated as the average bubble diameter in the thickness direction of each foam layer. did. The average cell diameter in the thickness direction of the white foam layer in the table is the average number of cells per side.

Moreover, about the obtained polystyrene-type resin plate-like laminated foam, the average value of the surface total reflectance, the lightness index (L ^* value), and the total light transmittance are obtained by the following methods, and the surface state (appearance) is as follows. Evaluation based on the criteria. The results are shown in Tables 1 and 2.

(Average value of total reflectance)
Using a UV-visible spectrophotometer, the total reflectance was measured every 10 nm at a wavelength between 380 and 770 nm, and the arithmetic average value was obtained.
(Lightness index (L ^* value))
Based on JIS Z8781-4: 2013, the lightness index (L ^* value) on both sides of the foamed plate was measured, and the lower value was taken as the lightness index (L ^* value) of the foamed plate. The lightness index of the single layer (uncolored) polystyrene foam plate (apparent density 60 kg / m ³ , thickness 5 mm) was 87.5.
(Total light transmittance)
In accordance with JIS K7375: 2008, the total light transmittance (%) of the foamed plate was determined. The total light transmittance of the single layer (uncolored) polystyrene foam plate (apparent density 60 kg / m ³ , thickness 5 mm) was 10.2%.
(appearance)
The appearance of the foam plate was visually evaluated according to the following criteria.
: Appears white and has the same appearance as a conventional single-layer polystyrene resin foam plate.
X: The inner black foam layer is seen through and grayish.

  From the results shown in Table 1, it was confirmed that the polystyrene resin plate-like laminated foams having the configurations of Examples 1 to 7 according to the present invention had all the brightness indexes of 70 or more and had a beautiful appearance.

  On the other hand, in the results of Comparative Examples 1 to 5 that did not satisfy the conditions of the present invention shown in Table 2, all the brightness indexes were less than 69. Moreover, all the external appearances were inferior compared with the Example.

  From these results, the polystyrene resin plate-like laminated foam of the present invention was produced by coextrusion, and in the polystyrene resin plate-like laminated foam having white foam layers on both sides of the black foam layer, the inner black foam layer It has been confirmed that this is a polystyrene-based resin plate-like laminated foam having a good light-shielding property, a high whiteness index and an excellent total reflectance due to the specific white foam layer of the outer layer, and a beautiful appearance. .

DESCRIPTION OF SYMBOLS 1 Polystyrene-type resin plate-like laminated foam 2 Black polystyrene-type resin foam layer 3 White polystyrene-type resin foam layer 4 Polystyrene-type resin 5 Black coloring agent 6 Bubble regulator 7 First extruder 8 Physical foaming agent 9 For black foam layer formation Resin melt 10 Polystyrene resin 11 White pigment 12 Bubble regulator 13 Second extruder 14 Physical foaming agent 15 White foam layer forming resin melt 16 Annular die 17 Pinch roll

Claims (6)

A plate-like laminated foam having an apparent density of 40 to 150 kg / m ³ , having a white polystyrene resin foam layer laminated and adhered by coextrusion on both sides of a black polystyrene resin foam layer,
The white polystyrene-based resin foam layer contains 1 to 12% by weight of white pigment with respect to 100% by weight of the resin composition constituting the foam layer, and the white pigment is titanium oxide,
The basis weight per side of the white polystyrene-based resin foam layer is 15 g / m ² or more,
The ratio of the basis weight per one side of the white polystyrene resin foam layer to the total basis weight of the foam is 0.2 or less,
The average cell diameter in the thickness direction of the white polystyrene resin foam layer is 0.25 mm or less,
The thickness per one side of the white polystyrene resin foam layer is 3 mm or less,
JIS Z8781-4: Ri der CIE1976 lightness index ^{L *} is 70 or more surfaces of the plate-like laminated foam-based 2013,
A polystyrene-based resin plate-like laminated foam, wherein the plate-like laminated foam is a display panel or a hydroponics panel . The polystyrene resin plate-like laminated foam according to claim 1, wherein the black polystyrene resin foam layer has a thickness of 1 mm or more . The average cell diameter in the thickness direction of the black polystyrene resin foam layer is 0.15 to 0.70 mm, and is larger than the average cell diameter in the thickness direction of the white polystyrene resin foam layer. Item 3. The polystyrene resin plate-like laminated foam according to Item 1 or 2. The apparent density of the white polystyrene-based resin foam layer is 30 to 150 kg / m ³ , and the polystyrene-based resin plate-like laminated foam according to any one of claims 1 to 3. The black polystyrene-based resin foam layer contains a black colorant, and the blending amount of the black colorant is 0.1 to 5% by mass with respect to 100% by mass of the resin composition constituting the foam layer. The polystyrene resin plate-like laminated foam according to any one of claims 1 to 4. 6. The polystyrene-based resin plate-like laminated foam according to claim 1, wherein the foam has an overall basis weight of 180 to 1800 g / m ² .

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