JP2015189039A - Polystyrene resin laminated expanded sheet, molding and expanded container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polystyrene resin laminated expanded sheet having excellent moldability, a molding having light weight and excellent impact resistance, and a container.SOLUTION: The polystyrene resin laminated expanded sheet is obtained by laminating an unexpanded layer of a thermoplastic resin on one or both surfaces of a polystyrene resin expanded layer. The density (g/cm) of the polystyrene resin laminated expanded sheet exceeds 0.20 and equal to or lower than 0.70 and the basis weight being the mass per 1 mthereof is 420-700 g/m. The tensile elongation percentage, which is measured according to JIS K7161 (1994), thereof in both of the extrusion direction (MD) and the width direction (TD) is 3.0-8.0% and a ratio (MD/TD) of the tensile elongation percentage is 0.80-1.25. The tensile strength thereof in both of the extrusion direction (MD) and the width direction (TD) is 100-180 N.

Description

  The present invention relates to a polystyrene-based resin laminated foam sheet, a molded body, and a foam container. More specifically, a polystyrene resin laminated foam sheet comprising a foamed layer formed by foaming a polystyrene resin and a non-foamed layer (solid layer) made of a thermoplastic resin provided on one or both surfaces of the foamed layer, The present invention relates to a molded body and a foam container using the laminated foam sheet.

  A resin foam sheet obtained by foaming a polystyrene-based resin is often used as a raw material for containers for storing foods and the like. The molded body of the resin foam sheet is characterized by being lightweight and having high heat insulation. However, the resin foam sheet thinned in order to increase the lightness has a weak strength, and there is a problem that the container may be broken or wrinkled when manufacturing the container by thermoforming, resulting in poor productivity. Further, there is a problem in that the molded container is insufficient in strength and impermeability is weakened.

  In the case of forming a deep-drawn container having a drawing ratio represented by the depth / bore of the container of 0.9 or more, the above problem becomes particularly significant. In response to this problem, Patent Document 1 proposes a laminated foam sheet in which a non-foamed resin film containing a graft rubber component is laminated on both surfaces of a polystyrene resin foam sheet.

JP 2012-126032 A

  However, even if a non-foamed resin film containing a rubber component is simply laminated on the foamed sheet as in the laminated foamed sheet disclosed in Patent Document 1, in practice, both formability and impact resistance are reached to practical levels. It is not easy. In particular, in Patent Document 1, a non-foamed resin film is laminated on both surfaces of a foamed sheet, but when a non-foamed resin film is laminated only on one side of the foamed sheet in order to meet the demand for further weight reduction. Has a problem that moldability and impact resistance are further deteriorated.

  The present invention has been made in view of the above circumstances, and provides a polystyrene-based resin laminated foam sheet excellent in moldability, and a lightweight molded article and container having excellent impact resistance comprising the polystyrene-based resin laminated foam sheet. Is an issue.

The polystyrene-based resin laminated foam sheet of the present invention is the polystyrene-based resin laminated foam sheet in which a thermoplastic resin non-foamed layer is laminated on one or both surfaces of the polystyrene resin foam layer. a of density (g / cm ³⁾ range of 0.20 ultra 0.70 or less, a basis weight of 420~700g / ^{m 2} is the mass per 1 m ^2, in conformity with JIS K7161 (1994) The tensile elongation in the extrusion direction (MD) and the width direction (TD) is 3.0 to 8.0%, and the ratio of (MD / TD) in the tensile elongation is 0.80 to 1.25. And the tensile strength in the extrusion direction (MD) and the width direction (TD) is 100 to 180 N.

  When a heating test is performed in which the polystyrene-based resin laminated foam sheet of the present invention is allowed to stand at 125 ° C. for 150 seconds, between a predetermined two points in the extrusion direction, the length before heating (MD1) and after heating The ratio (MD2 / MD1) of the length (MD2) is 0.80 to 1.00, and the length before heating (TD1) and the length after heating (TD2) between two predetermined points in the width direction. ) Ratio (TD2 / TD1) is 0.80 to 1.00 and the length (MD1) before heating is the same as the length (TD1) before heating ( MD2 / TD2) is preferably 0.90 to 1.10.

  The molded body of the present invention is a molded body formed by molding the polystyrene-based resin laminated foam sheet of the present invention.

  The container of the present invention is a container formed by thermoforming the polystyrene-based resin laminated foam sheet of the present invention.

  The container of the present invention may be a container formed with a drawing ratio represented by [depth / caliber] of 0.9 to 1.8.

The polystyrene resin laminated foam sheet of the present invention is excellent in moldability.
The container of the present invention is excellent in impact resistance while being lightweight. Furthermore, since the inner surface of the container can be impermeable, it is suitable for containing and distributing food containing moisture.

<< Polystyrene resin laminated foam sheet >>
<Physical properties>
The polystyrene-based resin-laminated foam sheet of the present invention (hereinafter sometimes simply referred to as a laminated foam sheet) includes a foamed layer obtained by foaming a polystyrene-based resin and thermoplastic resin on one or both sides of the foamed layer. It is a laminated foam sheet comprising a non-foamed layer made of resin.

The density (g / cm ³ ) of the laminated foamed sheet is in the range of more than 0.20 and 0.70 or less, preferably 0.30 to 0.60, more preferably 0.40 to 0.55, and 0.45. -0.50 is more preferable.
The impact resistance of a container can be improved more as it is more than the lower limit of the said range.
The lightness of a container can be improved more as it is below the upper limit of the said range.
That is, when it is in the above range, the impact resistance and light weight of the container can be balanced.

The basis weight is the weight of 1 m ² per laminated foam sheet is 420~700g / ^{m 2,} preferably 450~650g / ^{m 2,} more preferably ^{480~600g / m 2, 500~580g / m} 2 is Further preferred.
The impact resistance of a container can be improved more as it is more than the lower limit of the said range.
The lightness of a container can be improved more as it is below the upper limit of the said range.
That is, when it is in the above range, the impact resistance and light weight of the container can be balanced.

The laminated foam sheet has the following tensile properties in a tensile test based on JIS K7161 (1994).
The tensile elongation in the extrusion direction (MD) and the width direction (TD) of the laminated foamed sheet is 3.0 to 8.0%, and the ratio (MD / TD) of the tensile elongation is 0.80 to 1. Further, the tensile strength in the extrusion direction (MD) and the width direction (TD) is 100 to 180N.
Having the tensile properties described above can improve the impact resistance of the container as compared with the conventional case.

The tensile elongation in the extrusion direction (MD) and the width direction (TD) of the laminated foam sheet is preferably 4.0 to 8.0%, more preferably 4.5 to 8.0%.
100-170N are preferable, as for the tensile strength of the said extrusion direction (MD) and the width direction (TD), 100-150N are more preferable, and 110-140N are further more preferable.
Having the tensile properties described above can further improve the impact resistance of the container.

  When a heating test is performed in which the laminated foamed sheet is placed in a state where it is placed flat on a flat table at 125 ° C. for 150 seconds, the deformation is preferably within the following range.

The ratio (MD2 / MD1) between the length before heating (MD1) and the length after heating (MD2) (MD2 / MD1) is 0.80 to 1.00 between two predetermined points in the extrusion direction of the laminated foam sheet. ,
The ratio (TD2 / TD1) between the length before heating (TD1) and the length after heating (TD2) between two predetermined points in the width direction of the laminated foam sheet is 0.80 to 1.00. ,
And when ratio (MD2 / TD2) after the heating at the time of setting the length (MD1) before the said heating and (TD1) to the same length and performing the said heating test is 0.90. It is preferable that it is 1.10.
When the deformation after the heating test is within the above range, wrinkles and breakage are less likely to occur when a container is produced by thermoforming, and the moldability can be further improved.

  Here, since the ratio (MD2 / TD2) of the length after heating is based on the premise that the length (MD1) and (TD1) before heating are equal, {(MD2) / (MD1)} / { It is synonymous with (TD2) / (TD1)}.

The ratio (MD2 / MD1) is preferably 0.80 to 1.00, more preferably 0.80 to 0.90, and still more preferably 0.80 to 0.85.
The ratio (TD2 / TD1) is preferably 0.80 to 0.95, more preferably 0.80 to 0.90, and still more preferably 0.80 to 0.85.
The ratio (MD2 / TD2) is preferably 0.95 to 1.10, more preferably 0.95 to 1.06, and still more preferably 0.98 to 1.04.
When the deformation after the heating test is within the above range, wrinkles and breakage are less likely to occur when a container is produced by thermoforming, and the moldability can be further improved.

The following method can be applied as a specific method of the heating test. First, five flat square test pieces each having a side of 10 cm from the laminated foamed sheet, each side being parallel to the extrusion direction (MD direction) or the width direction (TD direction) of the laminated foamed sheet. cut.
Thereafter, two straight lines connecting the center portions of the sides facing each other are drawn in a cross shape on the laminated foamed sheet layer of each test piece. Next, each test piece is placed on a flat table in an oven with no humidity adjustment at 125 ° C., heated for 150 seconds, taken out of the oven, cooled at room temperature, and straight lines drawn in each direction before heating. The length is measured, and the arithmetic average value of the measured length of each test piece is defined as the length MD2 and TD2 after heating. In this way, the length before and after heating, MD1, 2, TD1, 2, can be measured.

  The thickness of the laminated foam sheet is determined in consideration of its use and the like.For example, when used for a container for food use, particularly a deep-drawn container, the total basis weight of the laminated foam sheet is within the above-mentioned range. Preferably there is.

  The thickness ratio (W1 / W2) of the thickness W1 of the foamed layer and the thickness W2 of the non-foamed layer constituting the laminated foamed sheet is not particularly limited, but balances the weight and impact resistance of the molded body and the container. From a viewpoint of improving well, 1.0-8.0 are preferable, 2.0-7.0 are more preferable, 3.0-6.0 are further more preferable, 4.0-5.0 are especially preferable.

  As described so far, by adjusting the physical properties of the laminated foam sheet as described above, it is possible to form a container that is light and free from wrinkles and cracks but has excellent impact resistance. Furthermore, this container can be formed as a deep-drawn container. In general, forming a deep-drawn container is more difficult than forming a shallow container, and it is easy to cause wrinkles and cracks during drawing by thermoforming, and the impact resistance of the formed container tends to be inferior. Since the physical properties of the foamed sheet are adjusted as described above, a deep-drawn container excellent in light weight and impact resistance can be formed without causing these problems. Of course, not only deep drawn containers but also shallow containers can be easily formed.

  In the laminated foam sheet, a thermoplastic resin non-foamed layer (solid layer) may be laminated only on one surface of the polystyrene-based resin foam layer (foamed layer), or the non-foamed layer is formed on both surfaces of the foamed layer. May be laminated.

  From the viewpoint of increasing the structural strength of the molded body and container of the present invention, it is preferable to provide the non-foamed layer on both sides of the foamed layer. On the other hand, from the viewpoint of reducing the weight of the molded product and the container of the present invention, a configuration in which the non-foamed layer is provided only on one surface of the foamed layer is preferable. In the present invention, even when the non-foamed layer is provided only on one side of the foamed layer, it has sufficient impact resistance.

<Polystyrene resin foam layer (foam layer)>
(Polystyrene resin)
The polystyrene resin constituting the foam layer is not particularly limited, and examples thereof include homopolymers or copolymers of styrene monomers. In addition, as a polystyrene resin, a copolymer having a styrene monomer as a main component, obtained by copolymerizing a styrene monomer and a vinyl monomer copolymerizable with the styrene monomer. May be used.
As the polystyrene-based resin, a polystyrene-based resin having 50% by mass or more of structural units based on styrene with respect to all the structural units is preferable, and polystyrene is more preferable.

Examples of the styrene monomer include styrene, α-methyl styrene, vinyl toluene, chlorostyrene, ethyl styrene, i-propyl styrene, dimethyl styrene, bromostyrene, and the like.
A styrene-type monomer may be used individually by 1 type, and may use 2 or more types together.

Examples of vinyl monomers copolymerizable with styrene monomers include alkyl (meth) acrylates such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, and cetyl (meth) acrylate. Bifunctional monomers such as (meth) acrylonitrile, dimethyl maleate, dimethyl fumarate, diethyl fumarate, ethyl fumarate, divinyl benzene, alkylene glycol dimethacrylate, and the like.
A vinyl-type monomer may be used individually by 1 type, and may use 2 or more types together.

  The polystyrene resin may be a rubber-modified polystyrene in which a diene rubber-like polymer (polybutadiene, styrene-butadiene copolymer, ethylene-propylene-nonconjugated diene three-dimensional copolymer, etc.) is graft-polymerized to polystyrene. Such resins include so-called high impact polystyrene (HIPS), acrylonitrile-butadiene-styrene copolymer (ABS), and the like.

  In the foamed layer, another resin may be blended with the polystyrene resin within a range where the polystyrene resin is a main component. Here, that the polystyrene-based resin is a main component means that the ratio of the polystyrene-based resin to the total resin component (100% by mass) of the foamed layer is 50% by mass or more.

Examples of the “other resin” include homopolymers of olefin monomers such as ethylene and propylene or copolymers thereof, and olefin monomers and vinyl monomers that can be polymerized therewith. And polyolefin resins such as copolymers, acrylic resins, acrylonitrile-styrene copolymers, and the like.
The amount of these other resins is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, and may be 0 parts by mass with respect to 100 parts by mass of the polystyrene-based resin. If it is below the above upper limit value, the resulting foamed layer will not be soft, and there is little risk of impairing the impact resistance of the molded container.

  Further, as the “other resin”, a rubber-like polymer having no styrene structural unit may be used. The rubbery polymer may be natural rubber or synthetic rubber. Examples thereof include synthetic rubbers such as chloroprene rubber, butyl rubber, nitrile rubber, hyperon, ethylene / propylene rubber, acrylic rubber, urethane rubber, and silicone rubber. These rubber-like polymers can be used in a range satisfying the above-mentioned rubber content.

Further, as the “other resin”, a polyphenylene ether resin may be used. By blending a polystyrene resin with a polyphenylene ether resin, the foamed layer has superior toughness, resistance to cracking, strength, and heat resistance compared to when the polystyrene resin is used alone. There is a case.
When the polyphenylene ether-based resin is blended with the polystyrene-based resin, the proportion of the polyphenylene ether-based resin is preferably 5% by mass or more and less than 50% by mass with respect to the total resin component (100% by mass), and 10 to 40% by mass. % Is more preferable.

The said polystyrene resin may be used individually by 1 type, and may use 2 or more types together.
In addition, the “other resin” may be used alone or in combination of two or more.

  The polystyrene resin used as a raw material can be a commercially available polystyrene resin, a polystyrene resin produced by a method such as suspension polymerization, a polystyrene resin that is not a recycled material (virgin polystyrene), a used foamed plate, Recycled raw materials obtained by reclaiming polystyrene-based resin foam molded articles (such as food packaging trays) can be used. As the recycled material, it is possible to use a recycled material obtained by recovering a used foamed plate or polystyrene-based resin foam-molded product and regenerating it by a limonene dissolution method or a heating volume reduction method.

(For rubber)
It is preferable that the rubber content (rubber) contained in the foamed layer is contained in the range of 1.0 to 10.0 mass% with respect to the total mass (100 mass%) of the foamed layer.
The range of the rubber content is preferably 1.5 to 9.6% by mass, more preferably 2.0 to 7.0% by mass, still more preferably 2.5 to 6.0% by mass. 0-5.0 mass% is especially preferable.
Impact resistance can be improved more as it is more than the lower limit of the said range.
A moldability can be improved more as it is below the upper limit of the said range.

  The rubber is an elastic component made of a high molecular polymer, and may be natural rubber or synthetic rubber.

  As the rubber component of the foamed layer, a rubber component derived from HIPS used as the polystyrene resin, or a rubber component (rubber) derived from a diene rubber-like polymer compounded separately from the polystyrene resin. preferable.

  Examples of the rubbery polymer blended separately from the polystyrene resin include chloroprene rubber, butyl rubber, nitrile rubber, hyperon, ethylene / propylene rubber, acrylic rubber, urethane rubber, and silicone rubber.

(Optional component)
The foam layer may contain, as optional components, additives such as a foam nucleating agent, a nucleating agent, a deodorant, an ultraviolet absorber, an antioxidant, a colorant, a lubricant, a flame retardant, and an antistatic agent. Good.
The kind and addition amount of the additive are appropriately determined according to the use of the polystyrene resin laminated foam sheet of the present invention.
One type of the additive may be used alone, or two or more types may be used in combination.

(Thickness of foam layer)
The thickness of the foamed layer is determined in consideration of the use of the polystyrene-based resin laminated foamed sheet of the present invention. For example, when used in a container for food use, particularly a deep-drawn container, the basis weight is 150 to 1000 g / A thickness of m ² is preferable, a thickness of 200 to 800 g / m ² is more preferable, and a thickness of 300 to 700 g / m ² is more preferable.
The impact resistance of a molded object and a container can be improved more as it is more than the lower limit of the said range. If it is not more than the upper limit of the above range, the lightweight properties of the molded product and the container can be further improved. That is, when it is in the above range, it is possible to balance the impact resistance and lightness of the molded body.

(Foaming ratio)
The foaming ratio of the foamed layer is not particularly limited, and is preferably 1.5 to 5.0 times and more preferably 1.7 to 4.5 times from the viewpoint of weight reduction while maintaining the strength of the foamed layer. preferable.
The impact resistance of a molded object and a container can be improved more as it is more than the lower limit of the said range. If it is not more than the upper limit of the above range, the lightweight properties of the molded product and the container can be further improved. That is, when it is in the above range, it is possible to balance the impact resistance and lightness of the molded body.

<Thermoplastic resin non-foamed layer (solid layer)>
(Thermoplastic resin)
The thermoplastic resin constituting the thermoplastic resin non-foamed layer (hereinafter sometimes simply referred to as a solid layer) is not particularly limited. For example, the polystyrene resin exemplified as the material resin of the foam layer, "Other resin" etc. are mentioned. Among these, from the viewpoint of improving the moldability and impact resistance of the molded product and the container by increasing the affinity and adsorbability of the solid layer to the foamed layer and harmonizing the physicochemical properties of both layers. The solid layer preferably contains the polystyrene resin as a main component. Here, that the polystyrene resin is a main component means that the ratio of the polystyrene resin to the total resin component (100 mass%) of the solid layer is 50 mass% or more.

The said polystyrene resin may be used individually by 1 type, and may use 2 or more types together.
In addition, the “other resin” may be used alone or in combination of two or more.

(For rubber)
The rubber content (rubber) contained in the solid layer is preferably in the range of 2.0 to 15.0 mass% with respect to the total mass (100 mass%) of the solid layer.
The range of the rubber content is more preferably 2.3 to 14.0% by mass.
The impact resistance of a molded object and a container can be improved more as it is more than the lower limit of the said range. The moldability of a molded object and a container can be improved more as it is below the upper limit of the said range.

  The rubber component of the solid layer may be the same rubber component as the foam layer or a different rubber component. The rubber component of the solid layer is preferably a rubber component derived from HIPS used as the polystyrene resin or a rubber component derived from a diene rubber-like polymer compounded separately from the polystyrene resin. .

(Optional component)
The solid layer may contain additives such as a deodorant, an ultraviolet absorber, an antioxidant, a colorant, a lubricant, a flame retardant, and an antistatic agent as optional components.
As the additive, a dummy foaming agent that does not actually foam may be added. By adding the dummy, the viscosity of the resin composition for the solid layer at the time of producing the polystyrene-based resin laminated foam sheet of the present invention can be adjusted according to the viscosity of the foam layer.
The kind and addition amount of the additive are appropriately determined according to the use of the polystyrene resin laminated foam sheet of the present invention.
One type of the additive may be used alone, or two or more types may be used in combination.

(Thickness)
The thickness of the solid layer is determined in consideration of the use of the polystyrene-based resin laminated foam sheet of the present invention. For example, when used in a container for food use, particularly a deep-drawn container, the basis weight is 40 to 300 g / preferably the thickness of the m ^2, more preferably a thickness which is a 70~250g / ^{m 2,} more preferably a thickness comprised between 100 to 200 g / ^{m 2.}
The impact resistance of a molded object and a container can be improved more as it is more than the lower limit of the said range. If it is not more than the upper limit of the above range, the lightweight properties of the molded product and the container can be further improved. That is, when it is in the above range, the impact resistance and light weight of the molded body and the container can be balanced.

  The solid layer described above may be laminated only on one side of the foam layer, or may be laminated on both sides of the foam layer. When laminated on both surfaces, the first solid layer laminated on one surface of the foam layer and the second solid layer laminated on the other surface of the foam layer may be the same. And may be different.

<Method for producing polystyrene-based resin laminated foam sheet>
A method for producing a laminated foam sheet in which the solid layer is laminated on at least one surface of the foam layer is not particularly limited, and a known method can be applied. For example, the following methods (1) to (4) may be mentioned.
[1] While supplying the resin for the foam layer and the foaming agent to the first extruder, the resin for the solid layer is supplied to the second extruder, and the first extruder and the second extruder are connected together. A method of laminating and integrating the solid layer on at least one surface of the foamed layer by supplying to the coextrusion mold and coextrusion,
[2] Before cooling the solid layer extruded from an extruder, a method of directly laminating and integrating on the separately produced foam layer,
[3] The foamed layer and the solid layer are respectively prepared in advance, and separately from this, a molten thermoplastic resin extruded from an extruder (preferably the thermoplastic resin constituting the solid layer). .) Is supplied onto the foam layer, and the solid layer is laminated and integrated on the foam layer using the thermoplastic resin as a binder,
[4] The foamed layer and the solid layer are respectively prepared in advance, and the solid layer is pressure-bonded onto the foamed layer while heating, and the solid layer is laminated on the foamed layer and integrated. Method, etc.
In addition, what is necessary is just to adjust the thickness of the said foaming layer and the said solid layer by a well-known method.

  In the case of printing on at least one surface of the solid layer, in addition to the method of printing on the solid layer after manufacturing the laminated foam sheet, in the manufacturing method of [3] and [4], the solid After printing on at least one surface of the layer, it may be laminated on the foamed layer and integrated. In addition, when printing is performed on at least one surface of the foam layer, it can be performed in the same manner as the method of printing on the solid layer.

<Molded body, container>
The molded body of the present invention is formed by molding the above-described polystyrene resin laminated foam sheet of the present invention. The molding method is not particularly limited, but thermoforming (heat processing) is preferable.
Examples of the molded body include trays having a shape in a plan view of a perfect circle, an ellipse, a semicircle, a polygon, a fan, a bowl-shaped container, a container having a bottomed cylindrical shape or a bottomed rectangular tube shape, for natto Examples of the container include a container with a lid such as a container, various containers such as a deep-drawn container for frozen confectionery foods, or a lid attached to the container body. Since these containers are constituted by the laminated foam sheet, they can be called foam containers. As the use of the container, food use is preferable.

  Since the polystyrene-based resin laminated foam sheet of the present invention is excellent in moldability, a deep-drawn container can be thermoformed. At this time, a deep-drawn container having a reduced thickness can be obtained without causing wrinkles or cracks (breaks).

  Here, the “deep-drawn container” means that the drawing ratio (depth of the deepest part divided by the diameter) represented by [depth of the deepest part of the bottom of the container] / [bore diameter (diameter)] is 0.9. It means the container which is the above. The diameter of the container is the diameter of a circle inscribed in the opening of the container, and the depth of the deepest part of the container can be defined as the distance from the scraped surface of the opening of the container to the deepest part of the bottom surface. .

  The drawing ratio of the deep-drawn container is preferably 0.9 to 1.8. When the drawing ratio is 1.8 or less, the moldability and impact resistance of the deep drawn container can be more reliably maintained.

The average thickness of the molded body is determined in consideration of applications and the like, for example, preferably 500 μm to 5000 μm, more preferably 700 μm to 2000 μm, and further preferably 900 μm to 1500 μm.
Within the above range, it is possible to balance the weight reduction of the molded body and the container and the improvement in impact resistance in a well-balanced manner.

  The overall density of the molded body is determined in consideration of usage and the like, and is the same as the overall density of the laminated foamed sheet.

  When the laminated foam sheet is a two-layer sheet in which the solid layer is laminated only on one side of the foam layer, the solid layer may form the inner wall surface of the container, or the outer wall surface of the container However, it is preferable to form the inner wall surface of the container. When the solid layer forms the inner wall surface of the container, breakage and wrinkles are less likely to occur during molding, the impact resistance of the molded container can be improved, and the moisture impermeability of the inner wall surface of the container can be improved. It is suitable as a container for food.

Although the taper angle of the side wall of the container constituted by the laminated foam sheet is not particularly limited, it can be, for example, in the range of 0 to 10 °.
Here, the “taper angle” is an angle corresponding to twice the angle (gradient angle) formed by the side surface of the container with respect to the horizontal surface (the scraped surface of the container opening) constituting the diameter of the container.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

[Example 1]
<Preparation of polystyrene resin laminated foam sheet (laminated foam sheet)>
As a resin composition for the foam layer, polystyrene GPPS resin (“HRM12N” manufactured by Toyo Styrene Co., Ltd.) 30% by mass, polystyrene GPPS resin (“HP-250” manufactured by DIC Co.), which is polystyrene A, B, and C shown in Table 1. To 100 parts by mass of a mixed resin composition containing 40% by mass and 30% by mass of polystyrene HIPS resin (“H350” manufactured by Toyo Styrene Co., Ltd.), 2.5 parts by mass of talc is mixed as a foam regulator, The rubber content was adjusted to 1.5% by mass. The obtained mixed raw material was supplied to a hopper of a first extruder of a tandem extruder to which a first extruder having an inner diameter of 90 mm and a second extruder having an inner diameter of 150 mm were connected. The maximum cylinder temperature of the extruder is 230 ° C., 0.98 parts by weight of butane (isobutane / normal butane = 70/30) is injected and kneaded as a foaming agent, and the foamable molten mixture is cooled in the second extruder. The resin temperature was adjusted to 166 ° C., and the resin flowed into the confluence mold at an extrusion rate of 150 kg / hr.

  As a resin composition for a non-foamed layer (solid layer), 55% by mass of polystyrene GPPS resin (“HP-250” manufactured by DIC), which is polystyrene B and C in Table 1, and polystyrene HIPS resin (manufactured by Toyo Styrene Co., Ltd.) “H350”) was mixed at 45 mass%, and the rubber content in the solid layer was adjusted to 2.3 mass%. The obtained mixture was supplied to a hopper of a single-screw extruder having an inner diameter of 120 mm, the cylinder temperature of the extruder was set to 230 ° C., and 0.84 parts by mass of butane (isobutane / normal butane = 70/30) as a blowing agent. The resin temperature of the foamable melt mixture was adjusted to 190 ° C. by press-fitting, kneading and cooling, and the mixture was poured into the confluence mold at an extrusion rate of 38 kg / hr.

  The above two types of resin merged in the merge mold are poured into an annular mold having a diameter of 280 mm, extruded as a cylindrical laminated foam material through a slit having a thickness of 0.6 mm, and along a cooling mandrel having a diameter of 670 mm. Taken up at a speed of 2.95 m / min, the cylindrical laminated foam material was incised with two cutters attached to the rear part of the mandrel, and two laminated foam sheets cut up and down were obtained. Air was blown into and out of the laminated foam sheet immediately after exiting the slit to cool the laminated foam sheet surface. The obtained laminated foam sheet was a sheet having a two-layer structure in which a solid layer was laminated on one side of the foam sheet.

  Each of <basis weight>, <thickness>, <average density>, <tensile elongation>, <tensile strength>, <heat deformation>, <formability>, and <drop impact resistance> of the obtained laminated foam sheet Measurement and evaluation were performed by the following methods and conditions.

<Measurement of basis weight>
-Overall basis weight: Eight or more points at equal intervals in the width direction of the laminated foamed sheet were cut into 10 cm x 10 cm, the mass of each piece was measured, and the average basis weight was obtained from this value by arithmetic mean.
-Basis weight of foam layer and solid layer: The basis weight of each layer was calculated from the overall basis weight measured above and the ratio of the extrusion discharge amount of each of the foam layer and the solid layer.

<Measurement of thickness>
Measure the thickness of the laminated foam sheet excluding both ends of 20mm in the width direction, using a dial thickness gauge SM-112 (manufactured by Teclock Co., Ltd.) at 9 or more points in the width direction. The average thickness was determined by averaging.

<Measurement of average density of sheet>
It calculated with the following formula from the whole basic weight and thickness of the lamination foam sheet.
Average density (g / cm ³ ) = total basis weight (g / m ² ) ÷ thickness (mm) ÷ 1000

<Calculation of rubber content>
-Rubber content of the foam layer: sliced to 0.5 mm thickness from the foam layer surface of the laminated foam sheet using a slicer (Split machine manufactured by Fortuna (Germany), model AB-320-D) Using the test piece as a sample, the rubber content of the test piece was measured by the above-described method for measuring the rubber content.
-Solid layer rubber content: Using the above slicer, a test piece sliced to a thickness of 0.05 mm from the surface of the solid foam side of the laminated foam sheet was used as a sample, and the rubber content measurement method described above was used. The rubber content of the test piece was measured.

When the obtained laminated foam sheet was measured by the above method, the total basis weight was 500 g / m ² (basis weight of the foam layer = 400 g / m ² , basis weight of the solid layer = 100 g / m ² ), and the thickness was 1. The rubber content of the solid layer / the rubber content of the foam layer = 2.3 / 1.5, and the average sheet density was 0.48 g / cm ³ . These results are shown in Table 1.

<Tensile elongation and strength>
About the obtained laminated foam sheet, based on JISK7161 (1994), the tensile elongation rate and tensile strength were measured as follows.
About the test piece, it cuts out from five places of equal intervals except the sheet | seat both ends 50mm along the TD direction of a laminated foam sheet using the type | mold type | mold of JISK7127 both in MD direction and TD direction, Tensilon universal Using a testing machine UCT-10T (Orientec Co., Ltd.), the distance between the grips was set to 80 mm, and measurement was performed at a tensile speed of 500 mm / min. The tensile elongation at this time was the average value (unit:%) of the elongation when the test piece was broken, and the tensile strength was the average value of the maximum tensile load (unit: N).

<Heating test>
A heating test was performed in which the obtained laminated foamed sheet was allowed to stand at 125 ° C. for 150 seconds. The distance between two points on the sheet before and after the heating was measured as follows.
Five flat square test pieces each having a side of 10 cm are cut out from the laminated foam sheet so that each side is parallel to the extrusion direction (MD direction) or the width direction (TD direction) of the laminated foam sheet. At this time, the length before heating is MD1, and TD1 is 10 cm.
Thereafter, two straight lines connecting the center portions of the sides facing each other are drawn in a cross shape on the laminated foamed sheet layer of each test piece. Next, each test piece is placed on a flat table in an oven with no humidity adjustment at 125 ° C., heated for 150 seconds, taken out of the oven, cooled at room temperature, and straight lines drawn in each direction before heating. The length is measured, and the arithmetic average value of the measured length of each test piece is taken as the length after heating.
From the obtained length MD2, TD2 after heating and the length MD1, TD1 before heating, the ratio of the length before heating (MD1) and the length after heating (MD2) in the extrusion direction (MD2 / MD1) The ratio (TD2 / TD1) of the length before heating (TD1) in the width direction and the length after heating (TD2) was calculated.
The results are shown in Table 1.

<Creation of container>
The obtained laminated foam sheet was molded so that the solid layer was inside the container. The molding conditions were as follows: furnace atmosphere temperature 155 to 175 ° C. and molding time 15 to 18 seconds, followed by thermoforming using a mold for manufacturing a round container having a diameter of 75 mm and a depth of 75 mm. The container formed here was a deep-drawn container, and its taper angle was 2 °.

<Formability evaluation>
○: A beautiful molded product was obtained.
Δ: Wrinkles were confirmed in the molded product. Or the thickness was extremely thin locally.
X: A molded product was not obtained.

<Drop impact test of container>
Ten test pieces were prepared by putting 75 g of water into the obtained container and sealing it to prepare 10 sealed ones. This was dropped from a height of 100 cm to the concrete floor so that the bottom of the container was down.
After the drop collision, the case where water did not leak from the container passed, the leaked one was rejected, and the number passed was counted. The results were evaluated as follows.

<Drop impact resistance evaluation>
○: 8 or more passed.
X: 7 or less were rejected.

[Example 2]
As a resin composition for a foam layer, polystyrene GPPS resin (“HP-250” manufactured by DIC) 40% by mass, polystyrene HIPS resin (“H350” manufactured by Toyo Styrene Co., Ltd.) 60 mass, which are polystyrene B and C in Table 1. % Was mixed with 3.0 parts by mass of talc as a foam regulator, and the rubber content in the foamed layer was adjusted to 3.0% by mass. The obtained mixed raw material was supplied to a hopper of a first extruder of a tandem extruder to which a first extruder having an inner diameter of 90 mm and a second extruder having an inner diameter of 150 mm were connected. The maximum cylinder temperature of the extruder is 230 ° C., 0.70 part by weight of butane (isobutane / normal butane = 70/30) is injected and kneaded as a foaming agent, and the foamable molten mixture is cooled in the second extruder. The resin temperature was adjusted to 167 ° C., and the resin flowed into the confluence mold at an extrusion rate of 160 kg / hr.

As the resin for the non-foamed layer (solid layer), 100% by mass of polystyrene HIPS resin (“H350” manufactured by Toyo Styrene Co., Ltd.), which is polystyrene C in Table 1, is used, and the rubber content in the solid layer is 5. 0%. This resin is supplied to a hopper of a single screw extruder having an inner diameter of 120 mm, the cylinder temperature of the extruder is set to 230 ° C., and 0.92 parts by mass of butane (isobutane / normal butane = 70/30) is injected as a foaming agent. After kneading and cooling, the resin temperature of the foamable molten mixture was adjusted to 190 ° C. and flowed into the confluence mold at an extrusion rate of 40 kg / hr. The basis weight (g / m ² ) of the foam layer / solid layer was set to 400/100.

  The above two types of resin merged in the merge mold are poured into an annular mold having a diameter of 215 mm, extruded as a cylindrical laminated foam material through a slit having a thickness of 0.7 mm, and along a cooling mandrel having a diameter of 553 mm. It was taken up at a speed of 3.8 m / min. Except this, it carried out similarly to Example 1, and obtained the laminated foam sheet. The obtained laminated foam sheet was a sheet having a two-layer structure in which a solid layer was laminated on one side of a foam layer.

The obtained laminated foam sheet has an overall basis weight of 500 g / m ² (foam layer basis weight 400 g / m ² , solid layer basis weight = 100 g / m ² ), thickness 0.95 mm, and solid layer rubber content. Content ratio / Rubber content ratio of the foam layer = 5.0 / 3.0 The average sheet density was 0.53 g / cm ³ .

The obtained laminated foam sheet was subjected to a tensile test and a heating test in the same manner as in Example 1. The results are shown in Table 1.
Moreover, the container sample was created similarly to Example 1 using the obtained laminated foam sheet, and the evaluation was performed. The results are shown in Table 1.

[Example 3]
As the resin composition for the foam layer, polystyrene GPPS resin (“HP-250” manufactured by DIC) 40% by mass, polystyrene HIPS resin (“H350” manufactured by Toyo Styrene Co., Ltd.), which is polystyrene B, C, E of Table 1. A mixed resin composition containing 27% by mass and 33% by mass of polystyrene HIPS resin (“EX-7” manufactured by Toyo Styrene Co., Ltd.) is used so that the rubber content in the foamed layer is 5.0% by mass. A laminated foam sheet was obtained in the same manner as in Example 2 except for the preparation.

The obtained laminated foam sheet has an overall basis weight of 500 g / m ² (foam layer basis weight 400 g / m ² , solid layer basis weight = 100 g / m ² ), thickness 1.05 mm, solid layer rubber content Content / Rubber content of foam layer = 5.0 / 5.0, and sheet average density was 0.48 g / cm ³ .

The obtained laminated foam sheet was subjected to a tensile test and a heating test in the same manner as in Example 1. The results are shown in Table 1.
Moreover, the container sample was created similarly to Example 1 using the obtained laminated foam sheet, and the evaluation was performed. The results are shown in Table 1.

[Comparative Example 1]
As a resin composition for a foam layer, polystyrene HIPS resin (“H350” manufactured by Toyo Styrene Co., Ltd.) 18% by mass, polystyrene GPPS resin (“HRM10N” manufactured by Toyo Styrene Co., Ltd.) 82% by mass, which are polystyrene C and D in Table 1. , 2.3 parts by mass of talc as a foam regulator was mixed with 100 parts by mass of the mixed resin composition, and the rubber content in the foamed layer was adjusted to 0.9% by mass. Further, as a resin composition for a non-foamed layer (solid layer), polystyrene GPPS resin (“G200C” manufactured by Toyo Styrene Co., Ltd.) 55% by mass, polystyrene HIPS resin (manufactured by Toyo Styrene Co., Ltd.), which are polystyrene F and G in Table 1. A mixed resin composition containing 45% by mass of “E640N”) was prepared, and the rubber content in the solid layer was 2.7%. Except these changes, it carried out similarly to Example 1 and obtained the laminated foam sheet.

The obtained laminated foam sheet has an overall basis weight of 480 g / m ² (the basis weight of each layer of the foam layer / solid layer is 400/80 in order), the thickness is 1.00 mm, and the rubber content of the solid layer / The rubber layer content of the foamed layer was 2.7 / 0.9, and the average sheet density was 0.48 g / cm ³ . Moreover, the container sample was created similarly to Example 1 using the obtained laminated foam sheet, and the evaluation was performed. The results are shown in Table 1.

The obtained laminated foam sheet was subjected to a tensile test and a heating test in the same manner as in Example 1. The results are shown in Table 1.
Moreover, the container sample was created similarly to Example 1 using the obtained laminated foam sheet, and the evaluation was performed. The results are shown in Table 1.

[Comparative Example 2]
As a resin composition for a non-foamed layer (solid layer), polystyrene GPPS resin (“HP-250” manufactured by DIC), which is polystyrene B and C in Table 1, 50% by mass, polystyrene HIPS resin (manufactured by Toyo Styrene Co., Ltd. “ H350 ") 50% by mass was prepared, and the rubber content in the solid layer was 2.5%. Furthermore, it flowed into the confluence mold at an extrusion rate of 60 kg / hr. A laminated foam sheet was obtained in the same manner as in Example 2 except that these were changed.

The obtained laminated foam sheet has an overall basis weight of 500 g / m ² (the basis weight of each layer of the foam layer / non-foam layer is 400/100 in order), the thickness is 0.95 mm, and the rubber content of the non-foam layer is contained. The rubber content of the foam layer was 2.5 / 3.0, and the average sheet density was 0.53 g / cm ³ .

The obtained laminated foam sheet was subjected to a tensile test and a heating test in the same manner as in Example 1. The results are shown in Table 1.
Moreover, the container sample was created similarly to Example 1 using the obtained laminated foam sheet, and the evaluation was performed. The results are shown in Table 1.

[Comparative Example 3]
As the resin composition for the foam layer, polystyrene GPS resin (“HRM12N” manufactured by Toyo Styrene Co., Ltd.) 80% by mass, which is polystyrene A and SBS of Table 1, polybutadiene-polystyrene copolymer resin (“Tufprene 125A manufactured by Asahi Kasei Kogyo Co., Ltd.) )) To 100 parts by mass of the mixed resin composition containing 20% by mass, 7.5 parts by mass of talc is mixed as a cell regulator so that the rubber content in the foamed layer is 12.0% by mass. Prepared. In addition, as a resin composition for a non-foamed layer (solid layer), polystyrene GPPS resin (“HRM12N” manufactured by Toyo Styrene Co., Ltd.), which is polystyrene A and SBS in Table 1, 95% by mass, polybutadiene-polystyrene copolymer resin ( Asahi Kasei Kogyo “Tufprene 125A”) 5 mass% was prepared, and the rubber content in the solid layer was 3%. Except these, it carried out similarly to Example 1, and obtained the laminated foam sheet.

The obtained laminated foam sheet has an overall basis weight of 500 g / m ² (the basis weight of each layer of the foam layer / solid layer is 400/100 in order), the thickness is 0.95 mm, and the rubber content of the solid layer / The rubber layer content of the foamed layer was 3.0 / 12.0, and the sheet average density was 0.53 g / cm ³ .

The obtained laminated foam sheet was subjected to a tensile test and a heating test in the same manner as in Example 1. The results are shown in Table 1.
Moreover, the container sample was created similarly to Example 1 using the obtained laminated foam sheet, and the evaluation was performed. The results are shown in Table 1.

From the results in Table 1, the deep-drawn containers made of the laminated foam sheets of Examples 1 to 3 whose tensile elongation and tensile strength were adjusted as described above were the containers of Comparative Examples 1 to 3 formed in the same shape. It was confirmed that the moldability and impact resistance were superior.
Examples 1 to 3 are containers using as a material a two-layer laminated foam sheet in which a non-foamed layer is formed only on one side of the foamed layer, and a conventional three-layer type (non-foamed layer / foamed layer). It is clear that the weight is reduced as compared with a container made of a sheet of / non-foamed layer.
In addition, in the two-layer laminated foam sheets of Examples 1 to 3, the thickness (basis weight) of the foam layer is about 4 times or more the thickness (basis weight) of the non-foamed layer, so that the weight is sufficiently reduced. ing.

  Note that Comparative Example 1 is inferior in evaluation because the tensile elongation in the width direction (TD) is out of regulation. Comparative Example 2 is inferior in evaluation because the ratio of (MD / TD) in tensile elongation is out of regulation. Comparative Example 3 is inferior in evaluation because the tensile elongation in the extrusion direction (MD) and the tensile strength in the width direction (TD) are not specified.

The rubber content of the thermoplastic resin used in the examples and comparative examples was measured by the method described later, and the following results were obtained. In addition, the measurement unit (%) of the following rubber content is based on mass (mass%) unless otherwise specified.
<General-purpose polystyrene resin (GPPS)>
GPPS manufactured by Toyo Styrene Co., Ltd .: Rubber content of product name “HRM12N” = 0%
GPPS manufactured by Toyo Styrene Co., Ltd .: Rubber content of trade name “HRM10N” = 0%
GPPS manufactured by Toyo Styrene Co., Ltd .: Rubber content of product name “G200C” = 0%
GPPS manufactured by DIC: rubber content of product name “HP-250” = 0%

<High impact polystyrene resin (HIPS)>
HIPS manufactured by PS Japan Co., Ltd .: rubber content of product name “E640N” = 6.0%
PS Japan HIPS: rubber content of product name “H350” = 5.0%
HIPS manufactured by PS Japan Co., Ltd .: rubber content of trade name “EX-7” = 11.0%

<Butadiene-styrene copolymer>
Asahi Kasei Kogyo Co., Ltd. Butadiene-Styrene Copolymer: Rubber content of trade name “Tufprene A” = 60%

The polystyrenes A to E and SBS in Table 1 are as follows.
Polystyrene A: rubber content of trade name “HRM12N” = 0%
Polystyrene B: rubber content of trade name “HP-250” = 0%
Polystyrene C: rubber content of trade name “H350” = 5.0%
Polystyrene D: Rubber content of trade name “HRM10N” = 0%
Polystyrene E: rubber content of trade name “EX-7” = 11.0%
Polystyrene F: rubber content of trade name “G200C” = 0%
Polystyrene G: rubber content of product name “E640N” = 6.0%
SBS: Rubber content of the product name “Tufprene 125A” = 60%

<Measurement of rubber content>
A 0.1-0.5 mg sample is precisely weighed and wrapped so as to be pressed against a ferromagnetic metal body having a Curie point of 590 ° C. (Pyrofoil; manufactured by Nihon Analytical Industrial Co., Ltd.). The butadiene monomer and 4-vinylcyclohexane produced by decomposition by Analytical Industries Co., Ltd. were measured using a gas chromatograph GC7820 (manufactured by Agilent Technologies) (detector: FID), and the total peak area was used in advance. Based on the prepared absolute calibration curve, the rubber content in the sample was calculated.

(Measurement condition)
・ Heating: 590 ° C, 5 sec
・ Oven temperature: 300 ℃
・ Needle temperature: 300 ℃
Column: Inter Cap5 (φ0.25mm × 30m, film thickness 0.25μm), manufactured by GL Sciences Inc.

(Column temperature condition)
-Temperature conditions: After holding at 50 ° C for 0.5 minutes, the temperature is raised to 200 ° C at 10 ° C / minute, further raised to 320 ° C at 20 ° C / minute, and held at 320 ° C for 0.5 minutes. Gas: He
・ He flow rate: 25 ml / min ・ Inlet pressure: 100 KPa
・ Inlet temperature: 300 ℃
-Detector temperature: 300 ° C
-Split ratio: 1/30

  As a standard sample for preparing a calibration curve, St / BD = 85/15 (CAT # 07073) resin manufactured by POLYSCIENCES. INC was used.

Claims (6)

In the polystyrene resin laminated foam sheet in which the thermoplastic resin non-foamed layer is laminated on one side or both sides of the polystyrene resin foam layer,
The polystyrene-based resin laminated foam sheet has a density (g / cm ³ ) in the range of more than 0.20 and 0.70 or less,
The basis weight which is the mass per 1 m ² is 420 to 700 g / m ² ,
Measured in accordance with JIS K7161 (1994), the tensile elongation in the extrusion direction (MD) and the width direction (TD) is 3.0 to 8.0%, and the ratio of the tensile elongation (MD / TD) Is a polystyrene-based resin laminated foamed sheet having a tensile strength of 100 to 180 N in the extrusion direction (MD) and the width direction (TD). When performing a heating test that is allowed to stand at 125 ° C. for 150 seconds,
The ratio (MD2 / MD1) between the length before heating (MD1) and the length after heating (MD2) (MD2 / MD1) is 0.80 to 1.00 between two predetermined points in the extrusion direction.
Between two predetermined points in the width direction, the ratio (TD2 / TD1) of the length before heating (TD1) and the length after heating (TD2) (TD2 / TD1) is 0.80 to 1.00, and
When the length before heating (MD1) and (TD1) are the same, the ratio of the length after heating (MD2 / TD2) is 0.90 to 1.10.
The polystyrene-based resin laminated foam sheet according to claim 1. The molded object formed by shape | molding the polystyrene-type resin laminated foam sheet of Claim 1 or 2. The foaming container formed by thermoforming the polystyrene-type resin laminated foam sheet of Claim 1 or 2. The foaming container according to claim 4, wherein a drawing ratio represented by [depth / caliber] is formed at 0.9 to 1.8. The foaming container according to claim 4 or 5 whose taper angle of a container side wall is 0-10 degrees.