JP6589117B2 - Polypropylene resin foam laminated sheet and molded product - Google Patents

Description

  The present invention relates to a polypropylene resin foam laminated sheet and a molded product thereof.

  Resin-made foam sheets are generally widely used for applications such as heat insulating materials, buffer materials, food containers and the like because they are excellent in moldability, heat insulating properties, buffer properties and the like. Especially, since the polypropylene-type resin foam sheet is excellent also in heat resistance, it is utilized suitably for the use of the food container which cooks with a microwave oven. However, since polypropylene resins exhibit low temperature brittleness (low impact resistance at low temperatures), ordinary polypropylene resin foam sheets cannot be said to be suitable for use in containers for frozen foods, for example.

  A polypropylene resin foam sheet in which the low temperature brittleness of the polypropylene resin is improved is disclosed in, for example, Japanese Patent Application Laid-Open No. 2001-139717 (Patent Document 1). This polypropylene resin foam sheet is obtained by mixing a polypropylene resin with a high density polyethylene resin having a density of 0.94 to 0.97 and a melt index at 190 ° C. of 0.01 or more and less than 1 (g / 10 minutes). , Low temperature brittleness has been improved.

  However, by including a high-density polyethylene resin in the constituent material of the polypropylene-based resin foam layer, the miniaturization of the bubbles in the foam layer is hindered by the influence of the high-density polyethylene resin. As a result, there has been a problem that the smoothness of the foam sheet surface is impaired and the appearance is lowered.

JP 2001-139717 A

  In a polypropylene resin foam sheet, it is desired to improve low-temperature brittleness while maintaining good appearance of the sheet surface.

The polypropylene resin foam laminated sheet according to the present invention is
A polypropylene resin foam layer, and a polystyrene resin non-foam layer laminated on at least one surface of the polypropylene resin foam layer,
The constituent material of the polystyrene resin non-foamed layer includes 50 to 80% by weight of polystyrene resin and 50 to 20% by weight of polyolefin resin.

  According to this structure, a moldability can be improved and low-temperature brittleness can be improved by lamination | stacking of the polystyrene-type resin non-foamed layer of the specific composition to a polypropylene-type resin foam layer. Since other components such as high-density polyethylene resin are not mixed with the polypropylene resin foam layer to improve low-temperature brittleness, the bubbles in the foam layer can be made finer, and the smoothness and appearance of the foam sheet surface are good. Can be maintained. Therefore, in the polypropylene resin foam sheet, the low temperature brittleness can be improved while maintaining the good appearance of the sheet surface.

The molded product according to the present invention is
It is formed by thermoforming the above-mentioned polypropylene resin foam laminated sheet.

  According to this configuration, it is possible to provide a molded product excellent in the appearance of the sheet surface and low temperature brittleness.

  Hereinafter, preferred embodiments of the present invention will be described. However, the scope of the present invention is not limited by the preferred embodiments described below.

As one aspect,
It is preferable that the constituent material of the polystyrene-based resin non-foamed layer further includes 0 to 10% by weight of a styrene-based thermoplastic elastomer.

As one aspect,
It is preferable that the constituent material of the polypropylene resin foam layer includes 60 to 100% by weight of polypropylene resin having strain hardening and 40 to 0% by weight of polypropylene resin having no strain hardening.

As one aspect,
It is preferable that the constituent material of the polypropylene resin foam layer contains only a polypropylene resin having strain hardening properties.

As one aspect,
The number of bubbles per 1 mm thickness in the polypropylene resin foam layer is preferably 10-30.

As one aspect,
It is preferable that the polystyrene-based resin non-foamed layer has a thickness of 5 to 200 μm.

As one aspect,
The density is preferably 0.15 to 0.85 g / cm ³ .

  Further features and advantages of the present invention will become more apparent from the following description of exemplary and non-limiting embodiments described with reference to the drawings.

Schematic cross section of polypropylene resin foam laminate sheet Schematic perspective view of the cut sheet piece

  An embodiment of a polypropylene resin foam laminated sheet will be described. As shown in FIG. 1, a polypropylene resin foam laminated sheet 1 of this embodiment includes a polypropylene resin foam layer 2 and a polystyrene resin non-foamed layer 3 laminated on one surface of the polypropylene resin foam layer 2. It has. The polypropylene resin foam laminated sheet 1 further includes a polypropylene resin non-foamed layer 4 laminated on the other surface of the polypropylene resin foam layer 2.

  The polypropylene resin foam layer 2 is a foam layer mainly composed of a polypropylene resin. The polypropylene resin constituting the polypropylene resin foam layer 2 is not particularly limited. For example, a propylene homopolymer, a block copolymer of propylene and another monomer, or a mixture of propylene and another monomer. It may be a random copolymer or the like. Moreover, as a polypropylene resin, what contains the polypropylene resin which has distortion hardening property can be used preferably. Here, “strain hardening” means a characteristic that the elongation viscosity of the polypropylene resin rapidly increases as the strain rate increases. As an example of a strain-hardening polypropylene resin, a polypropylene resin in which a branched structure is introduced into a molecular chain by electron beam irradiation or chemical crosslinking, or an entanglement between molecular chains by mixing ultra-high molecular weight components. An enlarged polypropylene resin can be mentioned.

  The polypropylene-based resin may include only the above-described strain-curable polypropylene-based resin, but may be a mixture with a polypropylene-based resin that does not have strain-hardening property. An example of a polypropylene resin that does not have strain hardening is a commercially available general linear polypropylene resin.

  When the constituent material of the polypropylene resin foamed layer 2 includes both a polypropylene resin having strain hardening and a polypropylene resin not having strain hardening, the blending ratio is 60:40 on a weight percent basis. It can be set to ~ 100: 0. By setting the content of the strain-curing polypropylene resin to 60% by weight or more, a foam having a high closed cell ratio can be obtained, and heat resistance and mechanical strength can be improved. A preferred example of the content of the strain-curable polypropylene resin in the constituent material of the polypropylene resin foam layer 2 is 100% by weight.

  The polypropylene-based resin foam layer 2 may contain a trace amount of additives as necessary. Examples of the additive include an antioxidant, an ultraviolet absorber, a stabilizer, a nucleating agent, a lubricant, a filler, a reinforcing material, a pigment, a dye, a flame retardant, and an antistatic agent.

  The thickness of the polypropylene resin foam layer 2 is not particularly limited, but may be, for example, 0.3 to 5 mm. If the thickness of the polypropylene resin foam layer 2 is less than 0.3 mm, rigidity and heat insulation may be insufficient, and if it is greater than 5 mm, moldability may be insufficient. The thickness of the polypropylene resin foam layer 2 is preferably 0.6 to 3 mm, and more preferably 0.8 to 2.4 mm.

  The closed cell ratio of the polypropylene resin foam layer 2 is not particularly limited, but may be, for example, 60% or more. If the closed cell ratio is less than 60%, the rigidity and heat insulating properties may be insufficient. The closed cell ratio is preferably 70% or more, and more preferably 80% or more. Moreover, the bubble diameter of the bubble contained in the polypropylene resin foam layer 2 is not particularly limited, but may be, for example, 8 to 300 μm, and preferably 10 to 220 μm.

  Furthermore, the number of bubbles per 1 mm thickness in the polypropylene resin foam layer 2 is not particularly limited, and may be, for example, 10 to 30. If the number of bubbles per unit thickness is less than 10, the heat insulating property may be insufficient, and the smoothness of the sheet surface is impaired and the appearance is deteriorated, and the non-foamed layers 3 and 4 are laminated. May be difficult to do. On the other hand, if the number exceeds 30, it may become brittle and formability may be insufficient. The number of bubbles per unit thickness is preferably 15-20.

  The polystyrene-based resin non-foamed layer 3 is a non-foamed layer mainly composed of a polystyrene-based resin. The polystyrene resin constituting the polystyrene resin non-foamed layer 3 is not particularly limited. For example, a homopolymer of styrene, a copolymer of styrene and another monomer, a mixture of polystyrene and another resin, or the like. It may be. Examples of other monomers and other resins include polyolefin resins, urethane resins, and acrylic resins. Among them, a mixture with a polyolefin resin can be preferably used, and the constituent material of the polystyrene resin non-foamed layer 3 preferably contains a polystyrene resin and a polyolefin resin.

  In this case, the blending ratio of the polystyrene-based resin and the polyolefin-based resin can be set to 50:50 to 80:20 on a weight percent basis. If the content of the polystyrene resin is less than 50% by weight, the effect of improving the low temperature brittleness by laminating the polystyrene resin non-foamed layer 3 may be insufficient. The resin non-foamed layer 3 may be easily peeled off from the polypropylene resin foamed layer 2. A more preferable blending ratio of the polystyrene-based resin and the polyolefin-based resin is 55:45 to 75:25 on a weight percent basis.

  In the above case, as the polystyrene-based resin, high impact polystyrene (HIPS) may be used.

  Moreover, the constituent material of the polystyrene resin non-foamed layer 3 may further contain a styrene thermoplastic elastomer. The styrenic thermoplastic elastomer is not particularly limited. For example, styrene-butadiene-styrene block copolymer (SBS) or a hydrogenated product thereof, styrene-isoprene-styrene block copolymer (SIS) or a hydrogenated product thereof, Styrene-isobutylene-styrene block copolymer (SIBS), styrene-ethylene-butadiene-styrene copolymer (SEBS), and the like can be used.

  For example, it is also preferable that the constituent material of the polystyrene resin non-foamed layer 3 includes a polystyrene resin, a styrene thermoplastic elastomer, and a polyolefin resin. In this case, the polystyrene resin is preferably 50 to 80% by weight, the styrene thermoplastic elastomer is preferably 0 to 10% by weight, and the polyolefin resin is preferably 50 to 20% by weight. A preferable blend is 55 to 75% by weight of polystyrene resin, about 5% by weight of styrene thermoplastic elastomer, and 40 to 20% by weight of polyolefin resin.

  The polystyrene-based resin non-foamed layer 3 may contain a trace amount of additives as necessary. Examples of the additive include an antioxidant, an ultraviolet absorber, a stabilizer, a nucleating agent, a lubricant, a filler, a reinforcing material, a pigment, a dye, a flame retardant, and an antistatic agent.

  The thickness of the polystyrene-based resin non-foamed layer 3 is not particularly limited, but may be, for example, 5 to 200 μm. If the thickness of the polystyrene-based resin non-foamed layer 3 is less than 5 μm, the effect of improving the low-temperature brittleness by laminating the polystyrene-based resin non-foamed layer 3 may be insufficient. Conversely, if it is thicker than 200 μm, the moldability may become insufficient, and the raw material cost will increase. The thickness of the polystyrene-based resin non-foamed layer 3 is preferably 5 to 100 μm, and more preferably 10 to 50 μm.

  The polypropylene resin non-foamed layer 4 is a non-foamed layer mainly composed of a polypropylene resin. The polypropylene resin constituting the polypropylene resin non-foamed layer 4 is not particularly limited. For example, a homopolymer of propylene, a copolymer of propylene and other monomers, or a mixture of polypropylene and other resins, etc. It may be.

  The polypropylene resin non-foamed layer 4 may contain a trace amount of additives as necessary. Examples of the additive include an antioxidant, an ultraviolet absorber, a stabilizer, a nucleating agent, a lubricant, a filler, a reinforcing material, a pigment, a dye, a flame retardant, and an antistatic agent.

  The thickness of the polypropylene resin non-foamed layer 4 is not particularly limited, but may be, for example, 5 to 200 μm. If the thickness of the polypropylene resin non-foamed layer 4 is less than 5 μm, the smoothness of the sheet surface may be impaired and the gloss may be lowered. Conversely, if it is thicker than 200 μm, the moldability may become insufficient, and the raw material cost will increase. The thickness of the polypropylene resin non-foamed layer 4 is preferably 20 to 100 μm, and more preferably 30 to 80 μm.

  The manufacturing method of the polypropylene resin foaming laminated sheet 1 includes a melting step, a foaming step, a sheet forming step, and a laminating step. In the melting step, the resin raw material of each layer is heated and melted. In the foaming step, the molten resin of the polypropylene resin foam layer 2 is foamed. As the foaming agent to be added at that time, for example, hydrocarbons, carbon dioxide, nitrogen, air, water and the like can be used, and two or more of these may be used in combination. In the sheet forming step, a sheet is formed from the molten resin of each layer using, for example, an extruder. In the laminating step, sheets of each layer are laminated. The sheet forming step and the laminating step may be performed sequentially as separate steps or may be performed simultaneously. That is, the sheets of each layer may be laminated after being formed in advance, or they may be laminated simultaneously with the extrusion forming of the sheets of each layer. In any case, the polypropylene resin foam laminated sheet 1 can be obtained through each of the above steps.

  Although the total thickness of the polypropylene resin foam laminated sheet 1 is not particularly limited, it depends on the thickness of each of the polypropylene resin foam layer 2, the polystyrene resin non-foam layer 3, and the polypropylene resin non-foam layer 4. For example, it may be 0.5 to 5.5 mm. The total thickness of the polypropylene resin foam laminated sheet 1 is preferably 1 to 3 mm.

Although the density of the whole polypropylene resin foaming laminated sheet 1 is not specifically limited, For example, it may be 0.15-0.85 g / cm < ³ >. If the overall density is less than 0.15 g / cm ^3, the strength when molded into a molded product and rigidity at high temperatures may be insufficient, and if it is greater than 0.85 g / cm ³ , There is a possibility that the heat insulating property at the time of molding becomes insufficient. The overall density of the polypropylene resin foam laminated sheet 1 is preferably 0.21 to 0.55 g / cm ³ , and more preferably 0.25 to 0.35 g / cm ³ .

  According to the polypropylene resin foam laminated sheet 1 of the present embodiment, the moldability (particularly deep drawability) is improved by laminating the polystyrene resin non-foamed layer 3 having a specific composition on the polypropylene resin foam layer 2. In addition, low temperature brittleness can be improved. In particular, low temperature brittleness can be improved without mixing other components such as high-density polyethylene resin in the polypropylene resin foam layer 2 in order to improve low temperature brittleness. Since other components are not mixed in the polypropylene resin foam layer 2, the bubbles in the foam layer can be made finer, and the smoothness and appearance of the foam sheet surface can be maintained well. Therefore, low temperature brittleness can be improved while maintaining good formability and appearance of the sheet surface.

  By performing thermoforming using such a polypropylene-based resin foam laminated sheet 1, a molded product excellent in the appearance of the sheet surface and low temperature brittleness can be obtained. Since the polystyrene-based resin non-foamed layer 3 is laminated, a soft and warm texture can be imparted to the molded product. In particular, the non-foamed polystyrene resin layer 3 is composed of a mixture of a polystyrene resin and a polyolefin resin (polypropylene resin), so that it has a unique soft and warm texture and pearl tone that is not found in each resin before mixing. A glossy feeling can be imparted to the molded product. In addition, since the foam layer is a polypropylene-based material, it has excellent heat resistance and can be used for heating in a microwave oven. Therefore, for example, the present invention can be suitably applied to a packaging container for frozen food that is scheduled to be cooked in a microwave oven.

  As the thermoforming method, for example, plug molding method, matched mold molding method, straight molding method, drape molding method, plug assist molding method, plug assist / reverse draw molding method, air slip molding method, snapback molding method, Examples include reverse draw molding, plug-and-ridge molding, and ridge molding.

  Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. However, the scope of the present invention is not limited by the specific examples described below.

[Example 1]
EX4000 (100% by weight) manufactured by Nippon Polypro Co., Ltd. was prepared as a resin material for the polypropylene resin foamed layer, and 2.6 weights of EE275F manufactured by Eiwa Kasei Kogyo Co., Ltd. was used as a nucleating agent for 100 parts by weight. It added in the ratio of the part, and mixed uniformly with the ribbon blender. As a resin material for the polystyrene-based resin non-foamed layer, HI408 manufactured by PS Japan Co., Ltd., BC3BRF manufactured by Nippon Polypro Co., Ltd., and TR2003 manufactured by JSR Co., Ltd. are prepared in a ratio of 55: 40: 5 on a weight percent basis. These were mixed uniformly with a ribbon blender. BC3BRF manufactured by Nippon Polypro Co., Ltd. was prepared as a resin material for the polypropylene resin non-foamed layer.

  As an extruder for a polypropylene resin foam layer, one 40 mmφ twin screw extruder (manufactured by Plastic Engineering Laboratory Co., Ltd., model: RT-40-S2-36-L, L / D = 36) was prepared. As extruders for polystyrene resin non-foamed layers and polypropylene resin non-foamed layers, two 40 mmφ single screw extruders (manufactured by GM Engineering, model: VGM40-25, L / D = 25) Got ready. The ends of these extruders were attached to a two-type three-layer feed block (manufactured by Clawren Japan, model: crawlen FG feed block), and a T-die was attached to this feed block.

  The cylinder temperature of a twin screw extruder for a polypropylene resin foam layer is 200 to 230 ° C., the cylinder temperature of a single screw extruder for a polystyrene resin non-foam layer is 210 ° C., and the single screw extrusion for a polypropylene resin non-foam layer. The cylinder temperature of the machine was set to 210 ° C., and the resin material was supplied to the hopper of each extruder and melted. Carbon dioxide (liquefied carbon dioxide) was injected as a foaming agent into the cylinder of the twin-screw extruder for the polypropylene resin foam layer, and further kneaded.

  Under atmospheric pressure, a three-layer sheet-like material was extruded by laminating a polypropylene resin non-foamed layer, a polypropylene resin foamed layer, and a polystyrene resin non-foamed layer by a coextrusion method. This three-layer sheet was passed through a water-cooled roll adjusted to 25 ° C. and quenched to obtain a polypropylene resin foam laminated sheet.

  Moreover, the molded product was produced from the obtained polypropylene-type resin foam lamination sheet using the small vacuum pressure forming machine (the Wakisaka engineering company make, model: FVS-500 type | mold). A polypropylene resin foam laminated sheet is fixed with a clamp of 50 × 40 cm, heated for about 15 seconds from the top and bottom with a heater at a set temperature of 300 ° C., and then a vertical shape of 165 × 165 × 56 mm by a differential pressure forming method. A container was obtained. At that time, thermoforming was performed so that the polystyrene-based non-foamed layer was on the outer side of the container and the polypropylene-based non-foamed layer was on the inner side of the container.

[Example 2]
In the same manner as in Example 1 except that the composition of the resin material of the polystyrene-based resin non-foamed layer was HI408: BC3BRF: TR2003 = 65: 30: 5 (% by weight) A molded product was obtained.

[Example 3]
In the same manner as in Example 1 except that the composition of the resin material of the polystyrene-based resin non-foamed layer was HI408: BC3BRF: TR2003 = 70: 25: 5 (% by weight) A molded product was obtained.

[Example 4]
In the same manner as in Example 1 except that the composition of the resin material of the polystyrene-based resin non-foamed layer was HI408: BC3BRF: TR2003 = 75: 20: 5 (% by weight) A molded product was obtained.

[Comparative Example 1]
In the same manner as in Example 1 except that the composition of the resin material of the polystyrene-based resin non-foamed layer was HI408: BC3BRF: TR2003 = 85: 10: 5 (% by weight) A molded product was obtained.

[Comparative Example 2]
In the same manner as in Example 1 except that the composition of the resin material of the polystyrene-based resin non-foamed layer was HI408: BC3BRF: TR2003 = 45: 50: 5 (% by weight) A molded product was obtained.

[Comparative Example 3]
A polypropylene resin foam laminated sheet and a molded product were obtained in the same manner as in Example 1 except that a polypropylene resin nonfoamed layer was provided on both sides of the polypropylene resin foamed layer without providing a polystyrene resin nonfoamed layer. Obtained.

[Evaluation]
For the polypropylene resin foam laminated sheets of Examples 1 to 4 and Comparative Examples 1 to 3, the thickness of the entire sheet, the thickness of the non-foamed layer, the density of the entire sheet, the closed cell ratio, and the number of bubbles per unit thickness were measured. . Moreover, the moldability, appearance, and cold resistance of the molded products of Examples 1 to 4 and Comparative Examples 1 to 3 were evaluated.

<Total thickness of sheet, thickness of non-foamed layer, number of bubbles per unit thickness>
A test piece having a size of 120 mm × 120 mm was cut out from a polypropylene resin foamed laminated sheet, and a cross section in the thickness direction was photographed with a scanning electron microscope (manufactured by JEOL Ltd., model: JCM-6000 Plus) at a photographing magnification of 40 times. did. In the photographed image, the thickness at the location where the test piece is equally divided into four in the width direction (three locations at 30 mm intervals indicated by black triangles in FIG. 2) is measured, and the average value thereof is obtained to determine the thickness of the entire sheet. did. Further, in the photographed image, the shortest distance from the sheet surface to the peripheral edge of the bubble at the above location was measured, and the average value thereof was obtained as the thickness of the nonfoamed layer. Also, in the photographed image, count the number of bubbles that overlap the vertical line along the thickness direction at the above location, calculate the average of those by the thickness of the entire sheet, round off the decimal point, and count the number of bubbles per unit thickness It was.

<Density>
A test piece having a size of 40 mm × 40 mm was cut out from the polypropylene resin foam laminated sheet, and the density was measured by an underwater substitution method using an electronic hydrometer (Mirage Trading Co., Ltd., model: ED-120T).

<Closed cell ratio>
A test piece having a size of 30 mm × 40 mm was cut out from a polypropylene resin foamed laminated sheet at approximately equal positions (three locations) in the width direction, an electronic balance (manufactured by Shimadzu Corporation, model: AUW220), and a gauge for thickness measurement. The weight and volume of the test piece were measured using (Mitutoyo Digimatic caliper, model: CD-10CX). Three test pieces were stacked to form a laminate, and an air comparison type hydrometer (manufactured by Tokyo Science Co., Ltd., model: 1000 type) was used to make the laminate by the 1-2-1 atmospheric pressure method according to ASTM D-2856. The volume was measured, and the closed cell ratio was calculated by the following formula.
Closed cell ratio [%] = (Vx−Vw) / (Va−Vw) × 100
Here, Vx is the volume [cm ³ ] of the laminate by an air comparative hydrometer, Vw is the total weight [g] of three test pieces / specific gravity [g / cm ³ ], and Va is 3 sheets. The total volume (apparent volume) [cm ³ ] of the test piece.

<Moldability>
About the obtained molded product, visually observe the appearance such as presence or absence of uneven thickness and the state of mold determination, as a whole, “○” is good, “×” is inferior, and “△” is inferior. did.

<Looks great>
About the obtained molded product, the appearance such as the presence or absence of surface gloss was visually observed, and “good” as a whole, “x” as inferior, and “△” as inferior.

<Cold resistance>
The molded article containing 200 g of water was kept cold at −40 ° C. for 24 hours, and then dropped from a height of 80 cm in a horizontal posture with respect to the floor surface. Thereafter, the presence or absence of cracks was visually observed, and those where no cracks were found were marked with “◯”, and those with cracks marked “x”.

  The above results are summarized in Table 1. In Comparative Example 1, the polypropylene-based resin foam layer and the polystyrene-based resin non-foamed layer were peeled off after molding, and various evaluations regarding the molded product could not be performed (indicated as “−”).

  As is clear from Table 1, all of the molded products of Examples 1 to 4 were excellent in moldability and cold resistance, and looked good. On the other hand, the molded products of Comparative Examples 1 to 3 were insufficient in moldability and cold resistance, or were peeled off and could not be evaluated. Comparing the results of Comparative Example 3 with the results of Examples 1 to 4, the lamination of the polystyrene-based resin non-foamed layer on the polypropylene-based resin foamed layer improves the moldability and improves the low-temperature brittleness. I understand that. Moreover, comparing the results of Comparative Examples 1 and 2 with the results of Examples 1 to 4, the moldability is improved only when the composition of the polystyrene resin non-foamed layer laminated on the polypropylene resin foamed layer is a specific composition. It turns out that the effect and the improvement effect of low-temperature brittleness are expressed.

[Other Embodiments]
(1) In the above embodiment, the configuration in which the polypropylene resin foam laminated sheet 1 includes the polystyrene resin non-foamed layer 3 on one side of the polypropylene resin foam layer 2 has been described as an example. However, the polystyrene resin non-foamed layer 3 may be provided on both surfaces of the polypropylene resin foamed layer 2 without being limited to such a configuration.

(2) In the above embodiment, as an example, the polypropylene resin foam laminated sheet 1 further includes a polypropylene resin non-foamed layer 4 in addition to the polypropylene resin foam layer 2 and the polystyrene resin non-foamed layer 3. explained. However, without being limited to such a configuration, for example, the polypropylene resin foam laminated sheet 1 does not include the polypropylene resin non-foamed layer 4, and only the polypropylene resin foam layer 2 and the polystyrene resin non-foamed layer 3 are provided. You may prepare.

(3) The specific resin material of each layer, its composition, thickness, closed cell ratio, bubble diameter, bubble number, and the like may be appropriately changed according to the required characteristics.

(4) In the above embodiment, the configuration in which the polypropylene resin foam layer 2, the polystyrene resin non-foam layer 3 and the polypropylene resin non-foam layer 4 are laminated by the coextrusion method has been described as an example. However, the present invention is not limited to such a configuration, and each layer may be laminated by another method such as an extrusion lamination method or a heat lamination method.

(5) In the above embodiment, the polypropylene resin foam laminated sheet 1 may further include a printed film layer laminated on at least one surface. In this case, the printing film layer laminated on the polystyrene resin non-foamed layer 3 can be a polypropylene resin film or a polystyrene resin film on which printing has been performed. Moreover, the printing film layer laminated | stacked on the polypropylene resin non-foaming layer 4 can be made into the polypropylene resin film to which printing was given.

(6) The configurations disclosed in each of the above-described embodiments (including the above-described embodiments and other embodiments; the same applies hereinafter) are applied in combination with the configurations disclosed in the other embodiments unless a contradiction arises. It is also possible to do. Regarding other configurations as well, the embodiments disclosed in the present specification are examples in all respects, and can be appropriately modified without departing from the gist of the present disclosure.

1 Polypropylene resin foam laminate sheet 2 Polypropylene resin foam layer 3 Polystyrene resin non-foam layer 4 Polypropylene resin non-foam layer

Claims (7)

A polypropylene resin foam layer, and a polystyrene resin non-foam layer laminated on at least one surface of the polypropylene resin foam layer,
The material of the polystyrene resin non-foamed layer, viewed contains 50 to 80% by weight polystyrene resin, and 50 to 20 wt% polyolefin resin, a
Polypropylene resin foam laminate in which the constituent material of the polypropylene resin foam layer includes 60 to 100% by weight of a polypropylene resin having strain hardening and 40 to 0% by weight of a polypropylene resin having no strain hardening. Sheet. A polypropylene resin foam layer, and a polystyrene resin non-foam layer laminated on at least one surface of the polypropylene resin foam layer,
The material of the polystyrene resin non-foamed layer, viewed contains 50 to 80% by weight polystyrene resin, and 50 to 20 wt% polyolefin resin, a
A polypropylene resin foam laminated sheet in which the constituent material of the polypropylene resin foam layer contains only a polypropylene resin having strain hardening properties . The polypropylene resin foam laminated sheet according to claim 1 or 2 , wherein the constituent material of the polystyrene resin non-foamed layer further comprises 0 to 10 wt% of a styrene thermoplastic elastomer. The polypropylene resin foamed laminated sheet according to any one of claims 1 to 3 , wherein the number of bubbles per 1 mm thickness in the polypropylene resin foamed layer is 10 to 30. The polypropylene-based resin foam laminated sheet according to any one of claims 1 to 4 , wherein the polystyrene-based resin non-foamed layer has a thickness of 5 to 200 µm. The polypropylene resin foam laminate sheet according to any one of claims 1 to 5 , wherein the density is 0.15 to 0.85 g / cm ³ . A molded product obtained by thermoforming the polypropylene resin foam laminated sheet according to any one of claims 1 to 6 .

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