JPH11300866A - Polycarbonate resin foamed panel having smooth surface, its production, and box - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polycarbonate resin foamed panel having good surface appearance, enhanced in bending strength and having a smooth surface, a method for producing the same, and a box formed of the foamed panel as a base material. SOLUTION: In a polycarbonate resin foamed panel having a smooth surface comprising a sheet-like laminated foam having a polycarbonate resin sheet as a base layer and the polycarbonate resin film or sheet formed at least on the single surface of the base layer as a surface layer, the density of the base layer of the foamed panel is 0.06-0.6 g/cm<3> , the thickness of the base layer is 1-10 mm, the melt tension at 250 deg.C of the polycarbonate resin forming the surface layer film or sheet of the foamed panel is 2.0 g or more, the surface center line average roughness of the surface layer film or sheet of the foamed panel is 3.0 μm or less and the bending strength Y (kg/cm<2> ) of the foamed panel satisfies the formula: Y>266X<2> +147X [wherein X is the apparent density (g/cm<3> ) of the foamed panel].

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polycarbonate resin foam plate having a smooth surface, a method for producing the same, and a box using the foam plate as a base material.

[0002]

2. Description of the Related Art A laminated polycarbonate resin foam sheet formed by coextrusion or extrusion lamination using a polycarbonate resin foam sheet as a base layer and a polycarbonate resin film as a surface layer is disclosed in JP-A-8-174780.
No. 1993. In these coextrusion methods or extrusion lamination methods, the viscosity average molecular weight of the polycarbonate resin used for the surface resin film is preferably less than 20,000, and when the molecular weight is 20,000 or more, the flowability is poor for coextrusion or extrusion lamination. It is described that the thickness of the laminate is likely to be uneven,
As examples, the viscosity average molecular weight is 18,000, 15,000
And 10000 polycarbonate resins (Examples 1, 7 and 9). However, even if the foamed sheet obtained by the above method is used as a plate material, its mechanical strength such as bending strength is not always sufficient, and in general, a foamed sheet wound in a roll shape is simply heated and rolled. Therefore, even if it is attempted to process the sheet into a plate shape, the appearance and the smoothness are inferior, such as the occurrence of waving at the end in the width direction of the foamed sheet.

[0003]

SUMMARY OF THE INVENTION The present invention provides a polycarbonate resin foam plate having a good surface appearance and improved bending strength, and having a smooth surface, a method for producing the same, and a box using the foam plate as a base material. Is the task.

[0004]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have completed the present invention. That is, according to the present invention, a foamed plate made of a sheet-like laminated foam having a polycarbonate-based resin foam sheet as a base layer and a polycarbonate-based resin film or sheet formed on at least one surface of the base layer as a surface layer, The density of the base layer of the foam board is 0.06 to 0.6 g / c
m ³ , the thickness of the base layer is 1 to 10 mm, and the thickness of the polycarbonate resin forming the surface film or sheet of the foamed board is 2
The melt tension at 50 ° C. is 2.0 g or more, and the center line average roughness of the surface film or sheet surface of the foamed board is 3.0 μm.
The present invention provides a polycarbonate-based resin foam board having a smooth surface, wherein the foam board has a flexural strength Y (kg / cm ² ) satisfying the following expression. Y> 266X ² + 147X (where X represents the apparent density (g / cm ³ ) of the foamed board) Further, according to the present invention, the resin for the base layer composed of the foaming agent-containing polycarbonate resin and the melt tension at 250 ° C. Is melted and kneaded in the extruder separately for the surface layer resin consisting of polycarbonate resin of 2.0 g or more, the latter melt kneaded material is the former melt kneaded material outer peripheral surface or inner peripheral surface or outer peripheral surface and inner peripheral surface A step of forming a film or sheet laminated tubular foam by co-extrusion using an annular die so as to be laminated on both sides, a step of cutting the tubular foam in the extrusion direction to form a sheet-shaped laminated foam, and A polycarbonate-based resin comprising a step of heating and stretching said sheet-like laminated foam in an extrusion direction at least 1.05 times and at least 1.02 times in a width direction orthogonal to the extrusion direction. Method for producing a foam plate is provided. Furthermore, according to the present invention, there is provided a box based on the polycarbonate resin foam board.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to obtain a polycarbonate resin foam plate having a smooth surface according to the present invention, first, a sheet-like laminated foam is produced by a conventionally known so-called coextrusion method or extrusion lamination method. In the coextrusion method, a polycarbonate resin foam sheet serving as a base layer and a polycarbonate resin film or sheet serving as a surface layer (hereinafter, “film or sheet” is simply abbreviated to “film”).
By using a extruder to simultaneously extrude a melt-kneaded product of the respective raw materials from a die and foam-lamination to obtain a sheet-like laminated foam. In the extrusion lamination method, a polycarbonate-based resin foam sheet serving as a base layer is prepared in advance, and on the surface of the foam sheet,
This is a method of obtaining a sheet-like laminated foam by extruding and laminating a melt-kneaded product of a polycarbonate-based resin, which is a raw material of a resin film to be a surface layer, from an extruder.

In the present invention, the polycarbonate resin used as a starting material is a polyester formed from carbonic acid and glycol or bisphenol.
Aromatic polycarbonate having diphenylalkane in the molecular chain is preferable because it has excellent heat resistance, weather resistance and acid resistance. Such polycarbonates include 2,2-bis (4-oxyphenyl) propane (also known as bisphenol A), 2,2-bis (4-oxyphenyl) butane, 1,1-bis (oxyphenyl) cyclohexane, And polycarbonates derived from bisphenols such as 1,1-bis (4-oxyphenyl) isobutane and 1,1-bis (4-oxyphenyl) ethane.

In the present invention, the polycarbonate resin forming the surface layer, that is, the resin film, needs to have a melt tension of at least 2.0 g at 250 ° C., preferably at least 2.3 g. In the production of a film-laminated polycarbonate resin foam sheet by the co-extrusion method or the extrusion lamination method described in JP-A-8-174780, the viscosity average molecular weight of the polycarbonate resin used for the surface resin film is preferably less than 20,000,
When the molecular weight is 20,000 or more, the fluidity is poor for coextrusion or extrusion lamination, the thickness of the obtained laminate is considered to be likely to be non-uniform, and the viscosity average molecular weight is 20.
Less than 000 are used. The polycarbonate resin having a viscosity average molecular weight of less than 20,000, which is considered to be preferable, usually has a melt tension at 250 ° C. of less than 2.0 g. In the present invention, when a polycarbonate resin having a melt tension of 2.0 g (250 ° C.) or more is used as a surface layer, that is, a resin for a resin film layer, surprisingly, the surface appearance is improved, the bending strength is improved, and the surface smoothness is improved. A polycarbonate resin foam plate can be obtained, and the foaming ratio of the foam as a base layer can be sufficiently increased by providing a surface layer by a co-extrusion method. The polycarbonate resin having a melt tension of 2.0 g (250 ° C.) or more usually has a viscosity average molecular weight of more than 20,000. Melt tension is 2.0g
(250 ° C.), the melt tension of the resin is low, so that when the foam as the base layer and the resin film as the surface layer are fused, the unevenness of the cells on the foam surface also appears on the resin film surface. As a result, the surface of the obtained laminated foam becomes rough, and the bending strength of the foamed board is significantly reduced. Further, at the time of co-extrusion, or at the time of secondary heating performed for removal of warpage, waving, and the like of the obtained laminated foam, the surface of the foam is easily burnt, and the appearance and smoothness of the surface are reduced. Good or improved bending strength cannot be obtained. The upper limit of the melt tension is not particularly limited, but is usually 30 g. In addition,
In this specification, the melt tension is measured as follows. As a measuring device, a melt tension tester type II manufactured by Toyo Seiki Seisaku-sho
250 ° C according to D1238, piston speed 10m
m / min, the orifice diameter was 2.095 mm, the orifice length was 8.00 mm, and the winding speed was 15.7 m / min.

In the present invention, of the above methods, the co-extrusion method is more preferably used. Hereinafter, a method for producing a sheet-like laminated foam mainly by a co-extrusion method will be described in detail. In the case of the co-extrusion method, a resin for a base layer made of a polycarbonate-based resin containing a foaming agent and a resin for a surface layer made of a polycarbonate-based resin having a melt tension of 2.0 g or more at 250 ° C. are separately melt-kneaded in an extruder. It is co-extruded from an annular die to form a film-laminated tubular foam, which is cut open to form a sheet-shaped laminated foam.

The polycarbonate resin for the surface layer preferably has a melt viscosity of 5 × 10 ³ to 2 × 10 ⁵ poise at 250 ° C. and a shear rate of 100 sec ⁻¹ , and 1 × 10 ⁴ poise.
〜1.7 × 10 ⁵ poise is more preferred. If the melt viscosity is too low, a resin having high fluidity exists on the outer periphery and / or inner periphery of the foamed layer (base layer) and on the extruder cylinder wall surface, so that the extrusion pressure is too low, and it is difficult to favorably foam the base layer. Become. If the melt viscosity is too high, the resin for the surface layer does not contain a foaming agent and has a much higher viscosity than the resin for the base layer.
Even with a resin having a melt tension of 2 g or more at ℃, it is difficult to prevent burnt on the foam surface. In this specification, the melt viscosity is measured as follows. As a measuring device, Cheist's Leovis 21
00, orifice diameter 1 mm, orifice length 10
mm, the measurement temperature was 250 ° C., and the shear rate was 100 sec ⁻¹ . Further, the polycarbonate resin for a surface layer preferably has a viscosity average molecular weight of 20,000 or more. More preferably, it is 22,000 or more. If the viscosity average molecular weight is too low, a sufficient melt viscosity cannot be obtained, and the above-mentioned problem may occur. On the other hand, if the viscosity average molecular weight is too high, the melt viscosity may be too high. Usually, the upper limit of the viscosity average molecular weight is 50,000.

Next, the polycarbonate resin for the base layer preferably has a viscosity average molecular weight of 25,000 or more.
More preferably, the melt tension at 28000 or more and at 250 ° C. are preferably 2.3 g or more, more preferably 5.0 g or more. If the viscosity average molecular weight is too low, the melt tension tends to be low, and the upper limit is not particularly limited, but is usually 50,000. If the melt tension at 250 ° C. is too low, it is difficult to maintain the formation of a foam film during foaming, and the foaming properties become insufficient. Although the upper limit is not particularly limited, it is usually 30 g. The polycarbonate resin for a base layer has a melt viscosity at a temperature of 250 ° C. and a shear rate of 100 sec ⁻¹ of 5 × 10 ⁴ to
2 × 10 ⁵ poise is preferred, and 6 × 10 ^{4 to} 1.8 × 10 ^4
5 poise is more preferred. If the melt viscosity is too low, it is difficult to maintain the extrusion pressure required for foaming. If the melt viscosity is too high, heat is generated in the extruder, and it is difficult to control the temperature to an appropriate foaming temperature. As the foaming agent, any of an inorganic foaming agent, a volatile foaming agent, and a decomposition-type foaming agent can be used. As the inorganic foaming agent, carbon dioxide, nitrogen and the like are used. Examples of the volatile blowing agent include lower aliphatic hydrocarbons such as propane, n-butane, i-butane, n-pentane, i-pentane and n-hexane; lower alicyclic hydrocarbons such as cyclobutane and cyclopentane. Used. The above-mentioned foaming agents can be used alone or in combination of two or more. For example, different types of foaming agents such as an inorganic foaming agent and a volatile foaming agent can be used in combination. In addition, a decomposition type foaming agent can be used in combination for adjusting the bubble diameter. The amount of the foaming agent used depends on the type of the foaming agent and the desired expansion ratio, and the expansion ratio determines the density of the base layer of the foamed board. It can be said that is determined.

[0011] The production of the sheet-like laminated foam is specifically performed as follows. In an extruder, on the one hand, the base layer polycarbonate resin is melt-kneaded with the foaming agent to form a foamable resin kneaded product, and on the other hand, the surface layer polycarbonate resin is separately melt-kneaded to form a resin kneaded product. It is co-extruded at a lower pressure than the inside of the extruder through an annular die provided at the extruder tip and foamed to form a tubular laminated foam having a foam as a base layer and a resin film as a surface layer, and is extruded into this tubular shape. The formed foam is cooled with air to form a balloon, taken up using a mandrel, and then cut open along the extrusion direction to obtain a sheet-like laminated foam. By employing such a co-extrusion method, the adhesive strength between the surface layer and the base layer can be increased, and the productivity can be significantly improved. In order to smoothly foam the polycarbonate resin for a base layer, it is advisable to add a cell regulator to the kneaded product of the resin and a foaming agent, if necessary. In this case, as the cell regulator, inorganic powders such as talc and silica, acidic salts of polyvalent carboxylic acids, and mixtures of polyvalent carboxylic acids with sodium carbonate or sodium bicarbonate are preferable. The addition amount is preferably 0.01 to 5.0 parts by weight, and more preferably 0.03 to 0.5 parts by weight, per 100 parts by weight of the resin. If the amount is less than 0.01 part by weight, it becomes practically difficult to foam the polycarbonate resin, while if the amount is more than 5.0 parts by weight, the physical properties of the obtained foamed molded article may be deteriorated.

The foamed resin kneaded material and the resin kneaded material forming the surface layer may contain ordinary foamed sheets such as a flame retardant, a heat stabilizer, a weather resistance improver, a coloring agent, an antistatic agent and the like. A known additive to be added to the composition can be added.
In addition, inorganic hydroxides such as aluminum hydroxide, calcium hydroxide, and magnesium hydroxide; inorganic carbonates such as calcium carbonate, magnesium carbonate, and barium carbonate; inorganic sulfites such as calcium sulfite and magnesium sulfite; calcium sulfate; and magnesium sulfate. , Inorganic oxides such as calcium oxide, aluminum oxide, silicon oxide, clays such as talc, clay, kaolin and zeolite or inorganic fillers such as natural minerals.
0% by weight may be added.

[0013] The sheet-like laminated foam obtained above is further biaxially stretched in the extrusion direction and the width direction orthogonal to the extrusion direction, whereby the resulting foamed board can be prevented from warping or waving. Further, the surface appearance and smoothness can be further improved. That is, the sheet-like laminated foam obtained as described above is heated online or offline by passing it through a heating furnace, and is 1.05 times or more, preferably 1.0 times or more in the extrusion direction.
It is stretched by heating to 8 times or more, 1.02 times or more, preferably 1.05 times or more in the width direction orthogonal to the extrusion direction, and then cut to a predetermined length in the extrusion direction to form a polycarbonate resin foam plate having a smooth surface. obtain. The stretching ratio is not particularly limited, but is usually 1.30 times in the extrusion direction and 1.20 times in the width direction. The stretching ratio in the extrusion direction and the stretching ratio in the width direction orthogonal to the extrusion direction are appropriately determined in consideration of the warpage and bending strength of the obtained stretched product. In the case of the extrusion direction, the stretching ratio is 1.05 times. On the other hand, in the width direction orthogonal thereto, it is advantageous that the ratio is 1.02 times or more. At draw ratios smaller than this, warping and waving of the foam sheet due to mandrel curl and flare,
Further, when the foamed sheet once wound up in a roll shape is stretched by heating, the curling may not be able to be eliminated.

The heating conditions for the heat stretching are as follows: a temperature at which the front and back surfaces of the foam are higher than the thermal deformation temperature (JIS K7207 (bending stress: 18.5 kg / cm ² )) of the polycarbonate resin which is the base resin of the base layer and the surface layer. It is preferable to heat so that Examples of the heating means include an infrared heating furnace and a hot roll. Note that heating the foam front and back surfaces so that the temperature is equal to or higher than the thermal deformation temperature of the polycarbonate resin as the base resin means that the foam is heated by a heating means such as a heating furnace and immediately after coming out of the heating means. The surface temperature of the foam is determined without delay by infrared temperature measurement, and the temperature is equal to or higher than the heat deformation temperature. The upper limit of the heating temperature equal to or higher than the heat deformation temperature is a temperature at which the surface state of the foam does not deteriorate due to defoaming, burning, or the like.

As the method of the heat stretching, a method of heating the sheet-like laminated foam in a heating furnace and then applying a tension by a roll or a conveyor or a method of applying a tension by heating and applying a heat roll. Such as the method of taking
Various combinations of heating means and take-off means can be employed. Stretching in the width direction can be carried out by a method in which both ends of the foam in the width direction are clamped and stretched by a widening device.

The polycarbonate resin foam board obtained by stretching as described above has a warpage value of 15 mm or less, the surface smoothness and appearance are further improved than before stretching, and the expansion ratio and The thickness can be changed to a value equal to or higher than that before stretching, such as an increase in thickness, a decrease in center line average roughness of the surface film surface, and an improvement in bending strength of a foamed plate. In addition, the warpage value of the foamed board refers to a foamed sheet sample for measurement obtained by cutting a sheet-shaped foam into a rectangular shape of 500 mm in the extrusion direction and the width of the foam in the direction perpendicular to the extrusion direction (the thickness is unchanged). The maximum height of the sample in a state where the sample was prepared and the sample was left standing on a horizontal plate-like member having a larger area (in a state where no force other than its own weight was applied) and the sample was turned upside down and left in the same manner Measure the length of the perpendicular dropped from the high part to the horizontal plate-like member,
The larger value (mm) of the front and back values obtained by subtracting the thickness of the sample from the length of the measured perpendicular line.

If the warp value exceeds 15 mm, the plate material has no commercial value, and specifically, the secondary workability and the like are poor. The warpage value can be adjusted by a heating temperature or a draw ratio.

The polycarbonate resin foam board obtained as described above has a smooth surface and good appearance, and has a base layer density of 0.06 to 0.6 g / cm ³ , preferably 0.1 to 0.6 g / cm ³ . 1 to 0.4 g / cm ³ , and the base layer thickness is 1
10 to 10 mm, preferably 1.5 to 7 mm, the center line average roughness of the surface film surface of the foamed board is 3.0 μm or less, preferably 2.5 μm or less, and the bending strength Y (kg / kg /
cm ² ) satisfies the following expression. Y> 266X ² + 147X (where, X represents a multiplied only foam board Density (g / cm ^3). It should be noted here, foamed plate surface to the base layer is laminated to the over only foam board density (g / cm ³⁾ Is the value obtained by reducing the weight (g) of the film by its volume (cm ³ ). In this specification, the center line average roughness of the film surface is 0.8 mm in cut-off value according to JIS B0601.
It is a value obtained by measuring in. In this specification, the bending strength Y of the foamed board is based on JIS K7171, and the conditions of a bending speed of 100 mm / min, a jig tip R of 5 mm, a span interval of 100 mm, and a test piece (50 mm in width × 150 mm in length × thickness of the foamed board) are used. It is a value obtained by measuring in.

In the polycarbonate resin foam board, if the density of the base layer is less than 0.06 g / cm ³ , the rigidity and the surface smoothness become insufficient,
If it exceeds 0.6 g / cm ³ , the lightness, cushioning property and heat insulating property will be insufficient. If the thickness of the base layer is less than 1 mm, the rigidity is insufficient. If the thickness is more than 10 mm, it is difficult to produce the base layer unless a special flat die is used. Failure occurs. When the center line average roughness of the surface film surface exceeds 3 μm, printability and appearance deteriorate. Although the lower limit is not particularly limited, it is usually 0.5 μm. If the bending strength Y does not satisfy the above expression, the rigidity of the plate is insufficient. The center line average roughness can be reduced by reducing the cell diameter of the foam constituting the base layer or by increasing the surface tension of the resin for dissolution. Further, in order to increase the bending strength Y, it can be adjusted by increasing the melt strength of the skin resin and further increasing the thickness of the surface film. In the foamed board of the present invention, the film thickness of the surface layer film is preferably from 10 to 500 µm, more preferably from 50 to 300 µm.

The polycarbonate resin foam plate having a smooth surface of the present invention has a good surface appearance, excellent bending strength, and impact resistance, heat resistance, smoothness, mechanical strength and mechanical strength at cryogenic temperatures as described above. Because of its excellent hinge properties, it is useful as a base material for various fields such as packaging, construction, and civil engineering, construction materials, and the like.
It is extremely useful as a base material for the bottom wall.

By using the polycarbonate resin foam board of the present invention as a base material, the following boxes can be produced (however, the present invention is not limited to these boxes only). A bottom surface member and a side member are coupled, and a heat-fusion box assembled by bending them, wherein a joining surface of each member of the box is heat-sealed, and a polycarbonate resin foam plate having a smooth surface. Heat fusion box consisting of An assembling box made of a polycarbonate resin foam plate having a smooth surface, in which a joint portion of each member of the box uses an adhesive, uses a joint fitting, or is fixedly connected by rivets. An assembling box comprising a polycarbonate resin foam plate having a smooth surface, which is assembled by connecting four side members, a bottom member, and / or a top member by fitting means formed at their edges. A folding box that can be folded flat, at least two opposing side members are vertically divided into at least two parts, and the divided parts are connected by a hinge mechanism, and the connection part is folded outward or inward. A folding box made of a polycarbonate resin foam plate with a smooth surface.

In the box of the present invention, since the polycarbonate resin foam plate having a smooth surface as a base material has a good surface appearance, excellent bending strength, and almost no warp, it is easy to manufacture and finished. Is beautiful and robust. In addition, since it has extremely excellent heat resistance and low-temperature brittleness, it is possible to store hot foods in a box, for example, and it is also possible to store it in a refrigerator or a freezer and refrigerate or freeze it. .

[0023]

Next, the present invention will be described in more detail by way of examples.

Examples 1 to 4 and Comparative Examples 1 to 3 For 100 parts by weight of a polycarbonate resin using bisphenol A shown in Table 1, 0.1 g of talc was used as a nucleating agent.
After heating, melting and kneading the raw resin in the first extruder to which 5 parts by weight was added, normal pentane 0.1 as a blowing agent was used.
7 to 0.4 mol / kg resin is press-kneaded into an extruder, and a polycarbonate resin using bisphenol A shown in Table 1 is melt-kneaded in a second extruder. Co-extrusion using an annular die so that the latter melt-kneaded material is laminated on the outer and inner circumferences of the melt-kneaded material,
A balloon was formed while cooling the inside and the outside of the cylindrical foam with air, and the balloon was taken out with a mandrel and then cut open along the extrusion direction to obtain a sheet-like double-sided film laminated foam. Next, the sheet-shaped double-sided film laminated foam is passed through a line arranged in the order of a delivery roll, a heating furnace and a transport chain in the heating furnace, a first take-out pinch roll, a second take-out pinch roll, and a cutting machine, and subjected to heat stretching. Then, trimming was performed between the first and second take-off pinch rolls, and the obtained laminated foam was cut in the width direction at every appropriate length in the extrusion direction to obtain a polycarbonate resin foam plate.
At this time, the draw ratio in the extrusion direction was defined as the speed ratio between the feed speed of the transfer chain in the heating furnace and the take-up speed of the first take-off pinch roll. The ratio of the width of the inlet to the width of the outlet of the transfer chain in the heating furnace was defined as the stretching ratio in the width direction. The method of adjusting the heating of the foam was performed by adjusting the overall line speed and the output of the heater in the heating furnace, and the temperature of the central portion in the width direction of the laminated foam was measured by an infrared temperature measuring device attached to the heating furnace outlet. . The physical properties and evaluation of the foamed board obtained by this stretching were as shown in Table 1.

The measuring methods and evaluation criteria for each physical property value in the above Examples and Comparative Examples are as follows. [Center line average roughness] JIS B0 using a surface roughness measuring device Surfcoder SE-30D manufactured by Kosaka Laboratory Co., Ltd.
According to 601, the center line average of both sides of the foamed plate under the conditions of a vertical magnification of 500, a horizontal magnification of 10, a reference length of 8.00 mm, a cut-off value of 0.8 mm, a stylus tip radius of 2 μm, and a feeding speed of 0.1 mm / sec. The roughness was measured and the larger value is shown in Table 1. [Bending strength of foam board] Using Tensilon UTM III type manufactured by Toyo Baldwin Co., Ltd., in accordance with JIS K7171, bending speed 100 mm / min, jig tip R5 mm,
Specimen (width 50 mm x length 15
(0 mm × foam plate thickness). [Smoothness of foamed board] The smoothness was evaluated by the warp value of the foamed board.・ ・ ・: Warpage value of 15 mm or less ×: Warpage value of more than 15 mm

[0026]

[Table 1]

[0027]

Industrial Applicability The foamed polycarbonate resin foam plate of the present invention has a good surface appearance, excellent bending strength, hardly any warpage, and is extremely useful as a substrate particularly for producing boxes and the like. . In addition, a box manufactured using the polycarbonate resin foam plate can be stored, for example, while food is hot, and can be refrigerated or frozen directly in a refrigerator or a freezer as it is, which is extremely convenient. Things.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Satoshi Iwasaki 3271-19 Tsuruta-cho, Utsunomiya-city, Tochigi Prefecture 2-101 Tsuruta Corp. No. 102

Claims (6)

[Claims] 1. A foamed plate comprising a polycarbonate-based resin foam sheet as a base layer, and a sheet-like laminated foam having a polycarbonate-based resin film or sheet formed on at least one surface of the base layer as a surface layer, wherein the foamed plate is The density of the base layer is 0.06 to 0.6 g / cm ³ , and the thickness of the base layer is 1 to
10 mm, the melt tension at 250 ° C. of the polycarbonate resin forming the surface film or sheet of the foamed board is 2.0 g or more, the center line average roughness of the surface film or sheet surface of the foamed board is 3.0 μm or less, and A foamed polycarbonate resin foam plate having a smooth surface, wherein the flexural strength Y (kg / cm ² ) of the foam plate satisfies the following expression. Y> 266X ² + 147X (where X represents the apparent density (g / cm ³ ) of the foamed board) 2. The foamed polycarbonate resin board according to claim 1, wherein the foamed polycarbonate resin board is made of a stretched product, and the warpage value of the foamed polycarbonate resin board is 15 mm or less. 3. The foamed polycarbonate resin sheet according to claim 1, wherein the laminated foam sheet is obtained by a co-extrusion method. 4. A resin for a base layer comprising a blowing agent-containing polycarbonate resin, and having a melt tension at 250 ° C. of 2.0.
g or more of the surface layer resin composed of a polycarbonate-based resin is individually melt-kneaded in an extruder, and the latter melt-kneaded material is formed on both the outer peripheral surface or the inner peripheral surface or the outer peripheral surface and the inner peripheral surface of the former molten kneaded material. A step of forming a film or sheet laminated tubular foam by co-extrusion and foaming using an annular die so as to be laminated, a step of cutting the tubular foam in the extrusion direction to form a sheet-shaped laminated foam, and A method for producing a polycarbonate resin foam plate, comprising a step of heating and stretching a sheet-like laminated foam in an extrusion direction at least 1.05 times and at least 1.02 times in a width direction orthogonal to the extrusion direction. 5. A resin for a base layer having a temperature of 250 ° C. and a shear rate of 1.
The melt viscosity at 00 sec ^-1 is 5 × 10 ⁴ to 2 × 1
0 is ⁵ poise and the temperature 250 ° C. of the resin for surface layer, a melt viscosity at a shear rate of 100 sec ^-1 is 5 × 10 ³ ~
^{5. The} method for producing a polycarbonate resin foam board according to claim 4, wherein the pressure is 2 × 10 ⁵ poise. 6. A box comprising the polycarbonate resin foam plate according to claim 1 as a base material.