JP6870162B1 - Polystyrene resin foam sheet and polystyrene resin foam container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To further improve moldability and blocking resistance of a polystyrene-based resin foam sheet. SOLUTION: In a polystyrene-based resin foamed sheet having a foamed layer 10 containing a polystyrene-based resin, silicone oil (A), optionally polyoxyethylene alkyl ether (b1), and coconut oil fatty acid diethanolamide (is) on one side or both sides. At least one type of surfactant (B) selected from b2) is present, and the abundance of the surfactant (B) is 2.5 parts by mass or less with respect to 100 parts by mass of the silicone oil (A). In the surface where the surfactant (B) is present on one side or both sides and the surfactant (B) is present, the abundance of the surfactant (B) is the amount of the surfactant. The total amount is 40 parts by mass or less with respect to 100 parts by mass. [Selection diagram] Fig. 1

Description

The present invention is a polystyrene-based resin foam sheet and a polystyrene-based resin foam container.

A container formed by molding a foamed sheet having a foamed layer containing a polystyrene-based resin (polystyrene-based resin foamed sheet) is often used as a raw material for a container or the like for accommodating food or the like.
As a method of molding a container (polystyrene resin foam container) from a polystyrene resin foam sheet, there is a method of heating a polystyrene resin foam sheet to soften it and sandwiching it in a mold to obtain a desired shape.

The polystyrene-based resin foam sheet is required to improve the productivity of the polystyrene-based resin foam container. Therefore, the polystyrene-based resin foam sheet is required to be able to obtain a polystyrene-based resin foam container having a good shape (excellent in moldability). In addition, the polystyrene-based resin foamed sheet is required to be able to easily take out individual polystyrene-based resin foamed containers (excellent in blocking resistance) after stacking the molded polystyrene-based resin foamed containers.
For example, Patent Document 1 discloses a polystyrene-based resin foam sheet in which a specific amount of silicone oil having a specific kinematic viscosity is applied to the surface. According to the invention of Patent Document 1, moldability and blocking resistance are improved.
Further, for example, Patent Document 2 discloses a polystyrene-based resin foam sheet having a surface coated with a silicone oil emulsion containing a base oil having a specific kinematic viscosity.
According to the invention of Patent Document 2, the moldability is improved.

Japanese Unexamined Patent Publication No. 2004-330650 Japanese Unexamined Patent Publication No. 2006-289742

However, there is a demand for polystyrene-based resin foam sheets to have higher moldability and blocking resistance.
Therefore, an object of the present invention is a polystyrene-based resin foam sheet capable of further enhancing moldability and blocking resistance.

Generally, the silicone oil is made into an emulsion dispersed in water and applied to the surface of a polystyrene resin foam sheet. The emulsion contains a surfactant to disperse the silicone oil in water. Therefore, a surfactant is present on the surface of the polystyrene-based resin foam sheet together with the silicone oil.
As a result of diligent studies by the present inventors, when a specific surfactant commonly used in emulsions is present on the surface of a polystyrene-based resin foam sheet in a specific amount or more, both moldability and / or blocking resistance are deteriorated. The present invention has been completed with the knowledge that it is allowed to be used.

The present invention has the following aspects.
<1>
In a polystyrene resin foam sheet having a foam layer containing a polystyrene resin,
Silicone oil (A) and at least one surfactant (B) optionally selected from polyoxyethylene alkyl ether (b1) and coconut oil fatty acid diethanolamide (b2) are present on one or both sides.
The abundance of the surfactant (B) is 2.5 parts by mass or less with respect to 100 parts by mass of the silicone oil (A).
The surfactant (B) is present on one side or both sides, and the surfactant (B) is present.
In terms of the presence of the surfactant (B), the polystyrene-based resin foam sheet has an abundance of the surfactant (B) of 40 parts by mass or less with respect to 100 parts by mass of the total amount of the surfactant.
<2>
The polystyrene-based resin foam sheet according to <1>, wherein the abundance of the silicone oil (A) is 0.001 to 0.20 g / m ^2.
<3>
The kinematic viscosity of the silicone oil (A) is 2000 mm ² / sec. The polystyrene-based resin foam sheet according to <1> or <2>, which is less than.
<4>
The polystyrene-based resin foam sheet according to any one of <1> to <3>, which has a non-foamed layer of a thermoplastic resin on one side or both sides of the foamed layer.

<5>
In a polystyrene resin foam container having a foam layer containing a polystyrene resin,
Silicone oil (A) and at least one surfactant (B) optionally selected from polyoxyethylene alkyl ether (b1) and coconut oil fatty acid diethanolamide (b2) are present on one or both sides.
The abundance of the surfactant (B) is 2.5 parts by mass or less with respect to 100 parts by mass of the silicone oil (A).
The surfactant (B) is present on one side or both sides, and the surfactant (B) is present.
A polystyrene-based resin foam container in which the abundance of the surfactant (B) is 40 parts by mass or less with respect to 100 parts by mass of the total amount of the surfactant in terms of the presence of the surfactant (B).
<6>
The polystyrene-based resin foam container according to <5>, wherein the abundance of the silicone oil (A) is 0.001 to 0.20 g / m ^2.
<7>
The kinematic viscosity of the silicone oil (A) is 2000 mm ² / sec. The polystyrene-based resin foam container according to <5> or <6>, which is less than.
<8>
The polystyrene-based resin foam container according to any one of <5> to <7>, which has a non-foamed layer of a thermoplastic resin on one side or both sides of the foamed layer.
<9>
The polystyrene-based resin foam container according to any one of <5> to <8>, which is for food use.

According to the polystyrene-based resin foam sheet of the present invention, moldability and blocking resistance can be further enhanced.

It is sectional drawing which shows an example of the polystyrene-based resin foam sheet of this invention. It is a flow chart which shows an example of the manufacturing process of the polyester resin of a plant origin. It is a flow chart which shows an example of the manufacturing process of the polyester resin of a plant origin. It is a flow chart which shows an example of the manufacturing process of the polyester resin of a plant origin. It is a perspective view which shows an example of the polystyrene-based resin foam container of this invention.

(Polystyrene resin foam sheet)
The polystyrene-based resin foamed sheet of the present invention (hereinafter, may be simply referred to as “foamed sheet”) has a foamed layer containing a polystyrene-based resin.
The foamed sheet may have a single-layer structure consisting of only a foamed layer, or a multi-layered structure having a non-foamed layer on one side or both sides of the foamed layer.

An embodiment of the foam sheet of the present invention will be described with reference to the drawings.
The foamed sheet 1 of FIG. 1 has a foamed layer 10 and a non-foamed layer 20 located on one surface of the foamed layer 10. The foamed sheet of the present invention may not have the non-foamed layer 20, or may have the non-foamed layer on the other surface of the foamed layer 10.

Silicone oil (A) and optionally a surfactant (B) are present on one side or both sides of the foamed sheet 1. In the present embodiment, either one surface (that is, the "second surface 21" which is the surface of the non-foaming layer 20) and the other surface (that is, the first surface 11 which is the surface of the foaming layer 10) or Silicone oil (A) is present in either one.
In the foam sheet 1, on the surface where the silicone oil (A) is present, the surfactant (B) of 2.5 parts by mass or less is arbitrarily present with respect to 100 parts by mass of the silicone oil (A).
That is, in the foamed sheet 1, the specific surfactant (B) does not exist or exists in a specific amount on the surface where the silicone oil (A) exists.
When silicone oil (A) is present on both sides of the foamed sheet 1, if the amount of the surfactant (B) on one surface of the foamed sheet 1 is 2.5 parts by mass or less, the surfactant on the other surface is used. The amount of (B) may be more than 2.5 parts by mass or less than 2.5 parts by mass. In other words, the foamed sheet 1 has at least one surface in which the silicone oil (A) and the specific surfactant are absent or the abundance of the specific surfactant is in a specific range.
When the silicone oil (A) is present on both sides of the foamed sheet 1, the amount of the surfactant (B) on both sides of the foamed sheet 1 is preferably 2.5 parts by mass or less.

The thickness T1 of the foamed sheet 1 can be determined in consideration of the intended use. For example, 500 to 4000 μm is preferable, and 1000 to 2500 μm is more preferable. When the thickness T1 is equal to or more than the above lower limit value, the strength of the foam container described later can be further increased. When the thickness T1 is equal to or less than the above upper limit value, the moldability can be further improved.

The basis weight of the foamed sheet 1 is appropriately determined with respect to the use of the foamed sheet 1, and for example, 50 to 1000 g / m ² is preferable, and 90 to 600 g / m ² is more preferable.

<Foam layer>
The foamed layer 10 is a layer formed by foaming a foamable resin composition containing a polystyrene-based resin, and bubbles are formed in the resin. The resin contained in the foamable resin composition (that is, the resin constituting the foamed layer 10) is a thermoplastic resin.
Examples of the polystyrene-based resin include homopolymers of styrene-based monomers such as styrene, α-methylstyrene, vinyltoluene, chlorostyrene, ethylstyrene, i-propylstyrene, dimethylstyrene, and bromostyrene, or copolymers thereof; A copolymer of a styrene-based monomer as a main component and a styrene-based monomer and a vinyl monomer polymerizable on the styrene-based monomer; a copolymer of a styrene-based monomer and a rubber component such as butadiene, a homopolymer of the styrene-based monomer, or a copolymer thereof. Examples thereof include so-called high-impact polystyrene, which is a mixture or polymer of a copolymer or a copolymer of a styrene-based monomer and a vinyl monomer and a diene-based rubber-like polymer.
Examples of the vinyl monomer that can be polymerized with the styrene-based monomer include alkyl (meth) acrylates such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, and cetyl (meth) acrylate, and (meth) acrylonitrile. Examples thereof include bifunctional monomers such as dimethyl maleate, dimethyl fumarate, diethyl fumarate, ethyl fumarate, divinylbenzene, and alkylene glycol dimethacrylate. These vinyl monomers may be used alone or in combination of two or more.
Here, "(meth) acrylate" represents one or both of "acrylate" and "methacrylate", and "(meth) acrylonitrile" represents one or both of "acrylonitrile" and "methacrylonitrile".
Examples of the diene-based rubber-like polymer include polybutadiene, styrene-butadiene copolymer, ethylene-propylene-non-conjugated diene three-dimensional copolymer and the like.
These polystyrene-based resins may be used alone or in combination of two or more.
As the polystyrene-based resin, a polystyrene-based resin containing 50 mol% or more of units derived from the styrene monomer is preferable, and polystyrene is more preferable.

The polystyrene-based resin may be a polystyrene-based resin that is not a recycled raw material, such as a general-purpose polystyrene resin (GPPS), a commercially available polystyrene-based resin, or a polystyrene-based resin newly prepared by a method such as a suspension polymerization method, or a recycled raw material. Polystyrene resin may be used.
Examples of the recycled raw material include used polystyrene-based resin foam molded products, for example, fish boxes, cushioning materials for home appliances, trays for food packaging, and the like, which are collected and recycled by a limonene melting method or a heat volume reduction method. Further, for example, examples of the recycled raw material include those obtained by crushing scraps generated after punching a tray for food packaging from a polystyrene-based resin foam sheet, melt-kneading them, and repelletizing them.
Recycled raw materials that can be used include home appliances (for example, TVs, refrigerators, washing machines, air conditioners, etc.) and office equipment (for example, in addition to those obtained by regenerating molded products such as used foam containers. Examples thereof include non-foamed polystyrene-based resins separated and collected from copiers, facsimiles, printers, etc.).

The mass average molecular weight Mw of the polystyrene-based resin is preferably 120,000 to 450,000, more preferably 150,000 to 400,000. The mass average molecular weight Mw is a value obtained by converting a value measured by GPC (gel permeation chromatography) based on a calibration curve using standard polystyrene.

The content of the polystyrene-based resin with respect to 100 parts by mass of the thermoplastic resin constituting the foam layer 10 is preferably 50 parts by mass or more, more preferably 75 parts by mass or more, further preferably 90 parts by mass or more, and particularly preferably 95 parts by mass or more. preferable. When the content of the polystyrene-based resin is at least the above lower limit value, the moldability of the foamed sheet 1 can be further enhanced, and the rigidity of the foamed container which is a molded product can be enhanced.
The upper limit of the content of the polystyrene-based resin is not particularly limited, and may be 100 parts by mass with respect to 100 parts by mass of the thermoplastic resin constituting the foamed layer 10.

The foamable resin composition may contain a thermoplastic resin other than the polystyrene-based resin. Examples of thermoplastic resins other than polystyrene resins include polyolefin resins such as polyethylene and polypropylene; poly (2,6-dimethylphenylene-1,4-ether) and poly (2,6-diethylphenylene-1,4-ether). ), Polyphenylene ether-based resin such as poly (2,6-dichlorophenylene-1,4-ether) and the like.

The foamable resin composition contains a foaming agent.
Examples of the foaming agent include hydrocarbons such as propane, butane and pentane; halogenated hydrocarbons such as tetrafluoroethane, chlorodifluoroethane and difluoroethane; among them, hydrocarbons are preferable, butane is preferable. As the butane, normal butane or isobutane may be used alone, or normal butane and isobutane may be used in combination at an arbitrary ratio. These foaming agents may be used alone or in combination of two or more.

The content of the foaming agent in the foamable resin composition is, for example, preferably 0.1 to 10 parts by mass, more preferably 1 to 7 parts by mass, and 1 to 5 parts by mass with respect to 100 parts by mass of the thermoplastic resin. Is even more preferable.

The foamable resin composition may contain components other than the thermoplastic resin and the foaming agent (hereinafter, also referred to as “arbitrary components”). Examples of the optional component include a bubble modifier, a stabilizer, an ultraviolet absorber, an antioxidant, a colorant, a deodorant, a lubricant, a flame retardant, an antistatic agent, and the like.
The type of the optional component is determined in consideration of the physical characteristics required for the foamed sheet 1. The optional component may be one kind alone or a combination of two or more kinds.

Examples of the bubble adjusting agent include a mixture of inorganic powders such as talc and silica. These bubble adjusting agents increase the closed cell ratio of the foam layer 10 and easily form the foam layer.
Examples of the stabilizer include a calcium-zinc heat stabilizer, a tin heat stabilizer, a lead heat stabilizer and the like.
Examples of the ultraviolet absorber include a cesium oxide-based ultraviolet absorber and a titanium oxide-based ultraviolet absorber.
Examples of the antioxidant include cerium oxide, cerium oxide / zirconia solid solution, cerium hydroxide, carbon, carbon nanotubes, titanium oxide, fullerene and the like.
Examples of the colorant include titanium oxide, carbon black, titanium yellow, iron oxide, ultramarine blue, cobalt blue, fired pigment, metallic pigment, mica, pearl pigment, zinc oxide, precipitated silica, cadmium red and the like.
Examples of the deodorant include silica, zeolite, zirconium phosphate, hydrotalcite calcined product and the like.

The content of the optional component in the foamable resin composition is, for example, preferably 0.05 to 20 parts by mass, more preferably 0.1 to 10 parts by mass, and 0.3, based on 100 parts by mass of the thermoplastic resin. ~ 5.0 parts by mass is more preferable. When the content of the arbitrary component is at least the above lower limit value, the effect derived from the arbitrary component can be exhibited. When the content of the optional component is not more than the above upper limit value, clogging to the die or the like can be better prevented, and the appearance of the foamed sheet 1 can be improved.

The thickness T10 of the foam layer 10 is, for example, preferably 0.3 to 5.0 mm, more preferably 0.4 to 3.0 mm, and even more preferably 0.5 to 2.5 mm. If the thickness T ₁₀ of the foam layer 10 is not less than the above lower limit, is increased more the impact resistance of the foam container. If the thickness T ₁₀ of the foam layer 10 is not more than the above upper limit, the foaming vessel lighter, and attained the further improvement of the moldability.

The basis weight of the foam layer 10 is, for example, preferably 50~600g / ^{m 2,} more preferably 90~500g / ^{m 2,} more preferably 150 and 400 / ^{m 2.} When the basis weight of the foam layer 10 is at least the above lower limit value, the impact resistance of the foam container can be further enhanced. When the basis weight of the foam layer 10 is not more than the above upper limit value, the foam container can be made lighter and the moldability can be further improved. In addition, when the basis weight of the foam layer 10 is not more than the above upper limit value, the heating time at the time of heat molding does not become too long, and the productivity of the foam container can be further increased.

The basis weight of the foam layer 10 can be measured by the following method.
Except for 20 mm at both ends in the width direction (TD direction) of the foam layer 10, 10 sections of 10 cm × 10 cm are cut out at equal intervals in the width direction, and the mass (g) of each section is measured up to 0.001 g. The value obtained by converting the average value of the mass (g) of each section into the mass ^{per 1 m 2 is} defined as the basis weight (g / m ² ) of the foam layer 10.

Apparent density of the foam layer 10 is, for example, preferably 0.050~0.666g / cm ^3, more preferably 0.066~0.500g / cm ^3, more preferably 0.100~0.333g / cm ³ .. When the apparent density of the foam layer 10 is at least the above lower limit value, the impact resistance of the foam container can be further enhanced. When the apparent density of the foam layer 10 is not more than the above upper limit value, the foam container can be made lighter and the heat insulating property can be further improved.
The apparent density of the foamed layer 10 is determined by measuring in accordance with JIS K 7222: 2005 "Foam plastics and rubber-How to determine the apparent density".
Specifically, the mass and apparent volume of the test piece of the foam layer 10 cut so as not to change the original cell structure are measured and calculated by the following formula (s).
Apparent density of foam layer 10 (g / cm ³ ) = mass of test piece (g) / apparent volume of test piece (cm ³ ) ... (s)

The foaming ratio of the foam layer 10 is, for example, preferably 1.5 to 20 times, more preferably 2 to 15 times, still more preferably 3 to 10 times. When the foaming ratio of the foamed layer 10 is at least the above lower limit value, the impact resistance of the foamed container can be further enhanced. When the foaming ratio of the foamed layer 10 is not more than the above upper limit value, the moldability of the foamed sheet 1 can be further improved.
The foaming ratio of the foamed layer 10 is a value obtained by dividing 1 by the “apparent density of the foamed layer 10 (g / cm ^3)”.

The average cell diameter of the foam layer 10 is, for example, preferably 80 to 450 μm, more preferably 150 to 400 μm, and even more preferably 200 to 350 μm. When the average cell diameter of the foam layer 10 is at least the above lower limit value, the impact resistance of the foam container can be further enhanced. When the average cell diameter of the foam layer 10 is not more than the above upper limit value, the surface smoothness of the foam container can be further enhanced.
The average cell size of the foam layer 10 can be measured according to the method described in ASTM D2842-69.

The closed cell ratio of the foam layer 10 is preferably 70% or more, more preferably 80% or more, further preferably 90% or more, and may be 100%. The closed cell ratio of the foamed layer is a value measured by the method described in JIS K7138: 2006 "Hard foamed plastic-How to obtain open cell ratio and closed cell ratio".

<Non-foam layer>
The non-foamed layer 20 is a layer made of a thermoplastic resin and in which bubbles are not substantially formed. In addition, the non-foaming layer 20 is a layer that does not substantially contain a foaming agent. The non-foaming layer 20 is a layer in which bubbles are not substantially formed, but when the non-foaming layer is formed by a coextrusion method or the like, a small amount of a foaming agent may be contained.
Examples of the thermoplastic resin constituting the non-foamed layer 20 include polystyrene-based resins and polyolefin-based resins similar to the thermoplastic resin constituting the foamed layer 10. Among them, the thermoplastic resin constituting the non-foamed layer 20 preferably contains a polystyrene-based resin.
When the thermoplastic resin constituting the non-foamed layer 20 contains a polystyrene-based resin, the adhesive strength between the non-foamed layer 20 and the foamed layer 10 is further enhanced.

Further, the non-foamed layer 20 may contain a low environmental load resin.
The low environmental load resin of the non-foaming layer 20 is preferably either a biodegradable resin or a plant-derived resin, or one of them.

The Z average molecular weight of the low environmental load resin is preferably 800,000 or less, more preferably 100,000 to 500,000, further preferably 150,000 to 450,000, and particularly preferably 150,000 to 400,000. When the Z average molecular weight of the low environmental load resin is within the above numerical range, the impact resistance of the foam container can be further enhanced.
The Z average molecular weight is measured in the same manner as the mass average weight Mw.

Examples of the biodegradable resin include polylactic acid resin, linear polyester of 3-hydroxybutyric acid and 3-hydroxyvaleric acid, polyether, polyacrylic acid, ethylene-carbon monoxide copolymer, and aliphatic polyester. -Polyester copolymer, aliphatic polyester-polyester copolymer, aliphatic polyester-aromatic polyester copolymer, aliphatic polyester-polyether copolymer, polymer alloy of starch and modified polyvinyl alcohol, starch and polyethylene Examples thereof include polymer alloys and succinic acid esters. From the viewpoint of enhancing oil resistance, the biodegradable resin is preferably a polylactic acid resin (PLA).

The polylactic acid-based resin is a resin obtained by polymerizing lactic acid by an ester bond. Polylactic acid-based resins are classified as polyester-based resins and are a type of biodegradable resin.
Specifically, the polylactic acid-based resin is a polymer produced from a monomer component containing both or one of D-lactic acid and L-lactic acid.

The polylactic acid-based resin is preferably a polymer of a monomer component consisting of both or only D-lactic acid and L-lactic acid (monomer component). In this case, it is preferable that the content ratio of one of D-lactic acid and L-lactic acid is higher than that of the other. Specific examples thereof include a monomer component composed of optical isomers of lactic acid having the following composition (I) and composition (II) content.

-Composition (I)
The upper limit of the content ratio of D-lactic acid in the total lactic acid (monomer component) is, for example, preferably 5% by mass or less, more preferably 4% by mass or less, and further preferably 3% by mass or less. The lower limit of the content ratio of D-lactic acid is, for example, 0% by mass or more, preferably more than 0% by mass. The lower limit of the content ratio of L-lactic acid in the total lactic acid (monomer component) is, for example, preferably 95% by mass or more, more preferably 96% by mass or more, and further preferably 97% by mass or more. The upper limit of the content ratio of L-lactic acid is, for example, 100% by mass or less, preferably less than 100% by mass.

・ Composition (II)
The upper limit of the content ratio of L-lactic acid in the total lactic acid (monomer component) is, for example, preferably 5% by mass or less, more preferably 4% by mass or less, and further preferably 3% by mass or less. The lower limit of the content ratio of L-lactic acid is, for example, 0% by mass or more, preferably more than 0% by mass. The lower limit of the content ratio of D-lactic acid in the total lactic acid (monomer component) is, for example, preferably 95% by mass or more, more preferably 96% by mass or more, and further preferably 97% by mass or more. The upper limit of the content ratio of D-lactic acid is, for example, 100% by mass or less, preferably less than 100% by mass.

In the case of a monomer component composed of an optical isomer of lactic acid having the content ratio of the composition (I), if the content ratio of D-lactic acid is not more than the above upper limit value, the crystallinity of the molded product such as a foam container is more excellent. It becomes a thing. In the case of a monomer component composed of an optical isomer of lactic acid having the content ratio of composition (II), if the content ratio of L-lactic acid is not more than the above upper limit value, the crystallinity of the molded product such as a foam container is more excellent. It becomes a thing. The composition (I) is preferable as the monomer component of the polylactic acid-based resin from the viewpoint of productivity and versatility, or from the viewpoint of enhancing oil resistance and moldability.

Further, the monomer component for producing the polylactic acid-based resin can contain a copolymerizable monomer other than lactic acid. Examples of the copolymerizable monomer include polyvalent carboxylic acid, polyhydric alcohol, hydroxycarboxylic acid, lactone and the like. Examples of the polyvalent carboxylic acid include aliphatic dicarboxylic acids such as succinic acid, adipic acid, suberic acid, sebacic acid and dodecanedioic acid, and aromatic dicarboxylic acids such as terephthalic acid. Examples of the polyhydric alcohol include dihydric alcohols such as ethylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol, and an ethylene oxide adduct of bisphenol A. Examples of the hydroxycarboxylic acid include glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 2-hydroxyn-butyric acid, 2-hydroxy3,3-dimethylbutyric acid, 2-hydroxy3-methylbutyric acid, and 2-methyllactic acid. , 2-Hydroxy-aliphatic dicarboxylic acid such as 2-hydroxycaproic acid and the like. Examples of the lactone include caprolactone, butyrolactone and valerolactone. These monomers may be used alone or in combination of two or more. The polylactic acid resin may also contain, for example, a trace amount of a chain extender such as a diisocyanate compound, an epoxy compound, or an acid anhydride.

From the viewpoint of productivity and versatility, or from the viewpoint of enhancing oil resistance and moldability, preferable polylactic acid-based resins include, for example, REVODE190 (manufactured by Kaisho Biomaterials Co., Ltd.) and HV-6250H (manufactured by Unitika Ltd.). ), Ingeo8052D (manufactured by NatureWorks), Ingeo4032D (manufactured by NatureWorks), and the like. Ingeo4032D (manufactured by NatureWorks) is a polylactic acid-based resin produced from a monomer component containing 98.7% by mass of L-lactic acid and 1.3% by mass of D-lactic acid.

When the biodegradable resin is a polylactic acid-based resin, the Z average molecular weight of the polylactic acid-based resin is preferably 800,000 or less, more preferably 100,000 to 500,000, further preferably 150,000 to 450,000, and even more preferably 150,000 to 40. 10,000 is particularly preferable. When the Z average molecular weight of the polylactic acid-based resin is within the above numerical range, the impact resistance of the foam container can be further enhanced.

Examples of the plant-derived resin include polymers derived from plant raw materials such as sugar cane and corn. "Derived from plant material" includes polymers synthesized or extracted from plant material. Further, for example, "derived from a plant raw material" includes a polymer obtained by polymerizing a monomer synthesized or extracted from a plant raw material. The "monomer synthesized or extracted from a plant material" includes a monomer synthesized from a compound synthesized or extracted from a plant material as a raw material. Plant-derived resins include those in which some of the monomers are "derived from plant materials".
Examples of the plant-derived resin include so-called bio-PET, bio-PE, bio-PP and the like, plant-derived polyester-based resin, plant-derived polyethylene-based resin, plant-derived polypropylene-based resin and the like.

The plant-derived resin will be described by taking polyethylene terephthalate resin (PET) and polyethylene furanoate resin (PEF) as examples.

The PET synthesis reaction is shown in Eq. (1). PET is synthesized by a dehydration reaction between n moles of ethylene glycol (EG) and n moles of terephthalic acid (Benzene-1,4-dicarboxic Acid). The stoichiometric mass ratio in this synthetic reaction is ethylene glycol: terephthalic acid = 30:70 (mass ratio). Both ends of the main chain of PET are hydrogen atoms.

［（１）式中、ｎは化学量論係数（重合度）であり、２５０〜１１００の数である。］

[In Eq. (1), n is a stoichiometric coefficient (degree of polymerization), which is a number of 250 to 1100. ]

Ethylene glycol is industrially produced by oxidizing and hydrating ethylene. In addition, terephthalic acid is industrially produced by oxidizing para-xylene.
Here, as shown in FIG. 2, ethylene is obtained by dehydration reaction of plant-derived ethanol (bioethanol), ethylene glycol synthesized from this ethylene (ethylene glycol derived from bioethanol), and terephthal derived from petrochemicals. When synthesizing PET from acid, the PET produced is 30% by mass of plant-derived PET.
Further, as shown in FIG. 3, paraxylene is obtained by dehydration reaction of plant-derived isobutanol (bioisobutanol), and PET is synthesized from terephthalic acid synthesized from this paraxylene and ethylene glycol derived from bioethanol. In this case, the PET produced is 100% by mass of plant-derived PET.

The PEF synthesis reaction is shown in Eq. (2). PEF is synthesized by a dehydration reaction between n moles of ethylene glycol and n moles of furandicarboxylic acid. The stoichiometric mass ratio in this synthetic reaction is ethylene glycol: frangylcarboxylic acid = 33:67 (mass ratio). Both ends of the main chain of PEF are hydrogen atoms.

［（２）式中、ｎは化学量論係数（重合度）であり、２５０〜１１００の数である。］

[In Eq. (2), n is a stoichiometric coefficient (degree of polymerization), which is a number of 250 to 1100. ]

Frangylcarboxylic acid (FDCA) is obtained by, for example, dehydrating plant-derived sugars such as fructose and glucose to obtain hydroxymethylfurfural (HMF) and oxidizing HMF.
As shown in FIG. 4, when both FDCA and ethylene glycol are derived from plants, the produced PEF is 100% by mass of plant-derived PEF.

The content of the low environmental load resin is preferably 90% by mass or less, more preferably 75% by mass or less, further preferably 60% by mass or less, and further preferably 50% by mass, based on the total mass of the resin contained in the non-foamed layer 20. The following is particularly preferable, and 40% by mass or less is most preferable. When the content of the low environmental load resin is not more than the above upper limit value, the impact resistance of the foam container can be further enhanced. The lower limit of the content of the low environmental load resin is preferably, for example, 3% by mass or more with respect to the total mass of the resin contained in the non-foamed layer 20. The content of the low environmental load resin may be 100% by mass with respect to the total mass of the resin contained in the non-foamed layer 20.

When the non-foaming layer 20 contains a biodegradable resin, the content of the biodegradable resin is preferably 3 to 90% by mass, preferably 5 to 75% by mass, based on the total mass of the resin contained in the non-foaming layer 20. Is more preferable, 10 to 60% by mass is further preferable, 15 to 50% by mass is particularly preferable, and 20 to 40% by mass is most preferable. When the content of the biodegradable resin is at least the above lower limit value, the environmental load can be further reduced. When the content of the biodegradable resin is not more than the above upper limit value, the impact resistance of the foam container can be further enhanced.

The non-foamed layer 20 may contain components other than the thermoplastic resin (hereinafter, also referred to as “arbitrary components”). Examples of the optional component include stabilizers, ultraviolet absorbers, antioxidants, colorants, deodorants, lubricants, flame retardants, antistatic agents and the like.
The type of the optional component is determined in consideration of the physical characteristics required for the foamed sheet 1. The optional component may be one kind alone or a combination of two or more kinds.

The thickness T20 of the non-foamed layer 20 is determined in consideration of the use of the foamed sheet 1 and the like. For example, 20 to 400 μm is preferable, 40 to 300 μm is more preferable, and 60 to 200 μm is further preferable. When the thickness T20 of the non-foamed layer 20 is at least the above lower limit value, the impact resistance of the foamed container can be further improved. When the thickness T20 of the non-foamed layer 20 is not more than the above upper limit value, the moldability of the foamed sheet 1 can be further improved.

<Silicone oil (A)>
Silicone oil (A) (hereinafter, may be referred to as component (A)) is present on one side or both sides of the foamed sheet 1 of the present embodiment. The presence of the component (A) on the surface of the foamed sheet 1 enhances moldability and blocking resistance. "The presence of silicone oil" means that not only all the components (A) are attached to the surface of the foamed sheet 1, but also a part of the component (A) infiltrates into the vicinity of the surface of the foamed sheet 1. Including the state of being.

The component (A) may be any as long as it conforms to the positive list of the Hygiene Council for Polyethylene and the like, and examples thereof include dimethyl silicone oil and methyl phenyl silicone oil which are widely used.

The kinematic viscosity of the component (A) is 2000 mm ² / sec. Less than 1700 mm ² / sec. Less than 1400 mm ² / sec. Less than is more preferred. When the kinematic viscosity of the component (A) is not more than the above upper limit value, the moldability and blocking resistance can be further improved. The lower limit of the kinematic viscosity of the component (A) is not particularly limited, but is substantially 200 mm ² / sec. The above is preferable, and 400 mm ² / sec. The above is more preferable, and 600 mm ² / sec. The above is more preferable.
The kinematic viscosity of the component (A) is a value measured at 25 ° C. in accordance with JIS K2283-2000.

In the foamed sheet 1, the presence of component (A), for example, preferably 0.001~0.20g / ^{m 2,} more preferably 0.002~0.050g / ^{m 2,} 0.004~0.02g / M ² is even more preferred. When the abundance of the component (A) is at least the above lower limit value, the moldability and blocking resistance can be further improved. When the abundance of the component (A) is equal to or less than the above upper limit value, the appearance can be improved and a more beautiful printing process can be performed.
The abundance of the component (A) in the foamed sheet 1 is a value measured by fluorescent X-rays.

The component (A) is preferably uniformly dispersed on the surface of the foamed sheet 1. Since the component (A) is uniformly dispersed, the moldability and blocking resistance can be further improved.
The uniformity of dispersion of the component (A) can be confirmed by the following method.
The spectral spectrum of the foamed sheet 1 is measured by the infrared spectroscopy once inversion type ATR method. In Tokurae was spectrum, the ratio of the maximum value of the peak intensity existing between 1250～1270Cm ^-1 and (I1260), the maximum value of the peak intensity existing between 1590～1610Cm ^-1 and (I1600) [( I1260) / (I1600)] (hereinafter, may be simply referred to as "maximum value ratio of peak intensity") is calculated.
The calculated maximum value ratio of the peak intensity is preferably 0.1 to 3, more preferably 0.1 to 1. If the ratio of the maximum value of the peak intensity is within the above range, it can be determined that the component (A) is uniformly dispersed.
In addition, I1260 is a peak caused by the expansion and contraction movement of Si-CH3 of the component (A).
I1600 is a peak caused by the in-plane skeletal vibration of benzene, which is a polystyrene resin, and its derivative.

<Surfactant (B)>
Surfactants (B) (hereinafter, may be referred to as component (B)) are polyoxyethylene alkyl ether (b1) (hereinafter, may be referred to as component (b1)) and coconut oil fatty acid diethanolamide (b2) ( Hereinafter, it is at least one selected from (sometimes referred to as (b2) component). In the foamed sheet 1, the moldability and blocking resistance are further enhanced by the absence of the component (B) or the abundance of the component (B) in a specific range in terms of the presence of the component (A). Be done.

The component (b1) is a polyoxyethylene alkyl ether. The component (b1) is, for example, a compound represented by the following formula (b1).

RO- (CH ₂ CH ₂ O) _n- H ... (b1)

In the formula (b1), R is an alkyl group having 8 to 18 carbon atoms. The carbon number of R is preferably 10 to 16, more preferably 12 to 15. When the carbon number of R is within the above range, the component (A) can be dispersed in water to form a highly stable oil-in-water emulsion. R may be a straight chain or a branched chain.
In the formula (b1), n represents the average number of repetitions of _{CH 2} CH _{2 O (oxyethylene group).}
n is preferably 3 to 50, more preferably 5 to 40.

In the foamed sheet 1, the abundance of the component (B) is, for example, preferably 2.5 parts by mass or less, more preferably 2.0 parts by mass or less, and 1.0 mass by mass with respect to 100 parts by mass of the component (A). It is more preferably parts or less, and may be 0 parts by mass. When the abundance of the component (B) is not more than the above upper limit value, the moldability and blocking resistance can be further enhanced. The lower limit of the abundance of the component (B) is not particularly limited.
The abundance of the component (B) in the foamed sheet 1 is measured by high performance liquid chromatography.

When the component (B) is present on one side or both sides of the foamed sheet 1, the abundance of the component (B) on the surface where the component (B) is present is 40% by mass with respect to 100 parts by mass of the total amount of the surfactant. It is preferably parts or less, more preferably 26 parts by mass or less, and even more preferably 12 parts by mass or less. When the abundance of the component (B) is not more than the above upper limit value, the moldability and blocking resistance can be further enhanced.

<Other surfactants>
In the foamed sheet 1, a surfactant other than the component (B) may be present on the surface on which the component (A) is present. Examples of the surfactant other than the component (B) include an anionic surfactant, a cationic surfactant, and a nonionic surfactant other than the component (B). In the foamed sheet 1, the amount of the surfactant other than the component (B) is not particularly limited. However, in the foamed sheet 1, there is no nonionic surfactant (other nonionic surfactant) other than the component (B), or the total amount (total amount of nonionic amount) of the component (B) and the other nonionic surfactant is , 2.5 parts by mass or less is preferable, 2.0 parts by mass or less is more preferable, and 1.0 part by mass or less is further preferable with respect to 100 parts by mass of the component (A). When the total amount of nonion is not more than the above upper limit value, the moldability and blocking resistance can be further improved.
Examples of other nonionic surfactants include polyoxyethylene fatty acid alkyl esters, fatty acid monoalkanolamides, fatty acid dialkanolamides (excluding the component (b1)) and the like. The carbon number of the fatty acid in the fatty acid monoalkanolamide and the fatty acid dialkanolamide is, for example, 8 to 18. The carbon number of the alkanol in the fatty acid monoalkanolamide and the fatty acid dialkanolamide is, for example, 1 to 5.

In the foamed sheet 1, it is preferable that the linear alkylbenzene sulfonate (C) (hereinafter, may be referred to as the component (C)) is present on the surface on which the component (A) is present. The component (C) is an anionic surfactant. The presence of the component (C) further enhances moldability and blocking resistance.
The number of carbon atoms of the alkyl group of the component (C) is preferably 10 to 14, for example.
Examples of the counter ion constituting the component (C) include alkali metals such as sodium and potassium, alkaline earth metals such as calcium and magnesium, and amines such as monoalkanolamine and dialkanolamine.
When the component (C) is present together with the component (A), the abundance of the component (C) is not particularly limited, but for example, 1 to 20 parts by mass is preferable with respect to 100 parts by mass of the component (A). ~ 16 parts by mass is more preferable, and 6 to 14 parts by mass is further preferable. When the abundance of the component (C) is at least the above lower limit value, the component (A) can be dispersed more uniformly to further improve moldability and blocking resistance. When the abundance of the component (C) is not more than the above upper limit value, the effect of the component (A) is not hindered, and the moldability and blocking resistance can be further enhanced.

In the foamed sheet 1, an anionic surfactant other than the component (C) may be present on the surface where the component (A) is present. Examples of the anionic surfactant other than the component (C) include α-olefin sulfonate, alkyl ether sulfate ester salt, monoalkyl phosphate ester salt and the like. The counterions constituting the salts of these anionic surfactants are the same as the counterions constituting the component (C).
When an anionic surfactant other than the component (C) is present on the surface where the component (A) is present, the total amount of the anionic surfactant (including the component (C)) is 100 parts by mass of the component (A). On the other hand, 1 to 20 parts by mass is preferable, 5 to 16 parts by mass is more preferable, and 6 to 14 parts by mass is further preferable.

The total amount of the surfactant (including the component (B) and the component (C)) is preferably 20 parts by mass or less, more preferably 16 parts by mass or less, and 14 parts by mass with respect to 100 parts by mass of the component (A). It is more preferably parts by mass or less, and may be 0 parts by mass. When the total amount of the surfactant abundant is not more than the above upper limit value, the effect of the component (A) is not hindered, and the moldability and the blocking resistance can be further improved.
The abundance of the linear alkylbenzene sulfonate (C) is preferably 60 parts by mass or more, preferably 74 parts by mass or more, based on 100 parts by mass of the total amount of the surfactant (including the components (B) and (C)). Is more preferable, 88 parts by mass or more is further preferable, and 100 parts by mass may be used. When the abundance of the component (C) is at least the above lower limit value, moldability and blocking resistance can be further enhanced.
The abundance of the component (C) in the foam sheet 1 is measured by high performance liquid chromatography.

(Manufacturing method of foam sheet)
The foamed sheet is manufactured by a conventionally known manufacturing method.
As a method for producing the foamed sheet 1, for example, a foamed layer raw fabric to be the foamed layer 10 and a non-foamed layer raw fabric to be the non-foamed layer 20 are manufactured, respectively, and the non-foamed layer raw fabric and the foamed layer raw fabric are used. , And this is thermocompression-bonded (thermocompression bonding method) to form a laminated body (lamination step), and a silicone emulsion is applied to one side or both sides of the laminated body (coating step).
Examples of the method for producing the laminated body include a method in which a non-foamed layer raw fabric and a foamed layer raw fabric are laminated and the layers are bonded to each other with an adhesive (bonding method).
As a method for producing the laminate, a method of extruding the resin which is a raw material of the non-foamed layer 20 to the surface of the foam layer raw material by T-die (T-die method), and a method of coextruding to provide the non-foamed layer 20 on the foamed layer 10. Examples thereof include a method of obtaining a laminated body (coextrusion method).

As a method for producing the non-foamed layer raw fabric, a known method for producing the non-foamed layer raw fabric can be adopted.
As a method for producing a non-foamed layer raw material, two or more types of resin pellets, which are raw materials for the non-foamed layer raw material, are melt-mixed in advance to form pellets (mixed pellets), which are supplied to an extruder to be melted. , The non-foamed layer raw material may be produced by kneading, or the mixed pellets may be subjected to a T-die method or a coextrusion method. Alternatively, one or more kinds of resin pellets may be supplied to an extruder to be melted and kneaded to produce a non-foamed layer raw fabric without producing mixed pellets, or a T-die method or a coextrusion method. May form a non-foamed layer. From the viewpoint of further enhancing the dispersibility of the low environmental load resin and further enhancing the impact resistance of the foam container, it is preferable to form the non-foamed layer using the mixed pellets.

As a method for producing the foam layer raw fabric, a known method for producing the foam layer raw fabric can be adopted.
First, a raw material composition containing a thermoplastic resin and other components and a foaming agent are supplied to an extruder to be melted and kneaded to obtain a foamable resin composition. The temperature at which the thermoplastic resin is melted (melting temperature: set temperature) is preferably 180 to 270 ° C., for example. When the melting temperature is at least the above lower limit value, the resin and other raw materials can be uniformly mixed. When the melting temperature is not more than the above upper limit value, the decomposition of the resin can be suppressed.

The foamed sheet 1 is obtained by applying a coating liquid containing a silicone emulsion to one or both sides of the laminate and then drying the surface of the laminate.
Examples of the coating method of the coating liquid include conventionally known methods, such as a roll coater method such as a gravure coater, and a spraying method.

The silicone emulsion is an oil-in-water emulsion that contains water, a component (A), and optionally a component (B), and is formed by dispersing the component (A) in water.
The content of the component (A) in the silicone emulsion is preferably 15 to 55% by mass, more preferably 20 to 50% by mass, still more preferably 25 to 45% by mass, based on the total mass of the silicone emulsion. When the content of the component (A) is at least the above lower limit value, the abundance of the component (A) on the surface of the foamed sheet 1 is sufficiently increased, and the moldability and the blocking resistance can be further improved. When the content of the component (A) is not more than the above upper limit value, the viscosity of the silicone emulsion is appropriately lowered, and the silicone emulsion can be more uniformly applied to the surface of the laminate.
The content of water in the silicone emulsion is preferably 45 to 85% by mass, more preferably 50 to 80% by mass, still more preferably 55 to 75% by mass, based on the total mass of the silicone emulsion. When the water content is at least the above lower limit, the viscosity of the silicone emulsion is appropriately lowered, and the silicone emulsion can be more uniformly applied to the surface of the laminate. When the water content is not more than the above upper limit value, the abundance of the component (A) on the surface of the foamed sheet 1 is sufficiently increased, and the moldability and blocking resistance can be further improved.
The coating liquid is a silicone emulsion diluted with water, and the dilution ratio is preferably 2 to 100 times, more preferably 3 to 60 times, still more preferably 5 to 20 times. When the dilution ratio is at least the above lower limit value, the viscosity of the coating liquid is appropriately lowered, and the coating liquid can be more uniformly applied to the surface of the laminate. When the dilution ratio is not more than the above upper limit value, the abundance of the component (A) on the surface of the foamed sheet 1 is sufficiently increased, and the moldability and blocking resistance can be further improved.

The content of the component (B) in the coating liquid is preferably 2.5 parts by mass or less, more preferably 2.0 parts by mass or less, and 1.0 part by mass or less with respect to 100 parts by mass of the component (A). More preferably, it may be 0 parts by mass. When the content of the component (B) is not more than the above upper limit value, the moldability and blocking resistance can be further enhanced.
The content of the component (C) in the coating liquid is preferably 1 to 20 parts by mass, more preferably 5 to 16 parts by mass, and even more preferably 6 to 14 parts by mass with respect to 100 parts by mass of the component (A). When the abundance of the component (C) is at least the above lower limit value, the component (A) can be dispersed more uniformly to further improve moldability and blocking resistance. When the abundance of the component (C) is not more than the above upper limit value, the effect of the component (A) is not hindered, and the moldability and blocking resistance can be further enhanced.

The coating amount of the coating liquid to the laminate is preferably 0.01 to 2.0 g / ^{m 2,} more preferably ^{0.05~1.0g / m 2, 0.1~0.7g / m} 2 and more preferable. When the coating amount of the coating liquid is at least the above lower limit value, the moldability and blocking resistance can be further improved. If the amount of the coating liquid applied is not more than the above upper limit value, a more beautiful printing process can be performed.

The coating liquid may contain a surfactant other than the component (B) and the component (C). The types and amounts of the surfactants other than the component (B) and the component (C) are the same as those of the surfactants other than the components (B) and (C) in the foamed sheet 1.

The coating liquid may contain a component (A), a component (B), a component (C), and an optional component other than the surfactant other than the component (B) and the component (C). Examples of the optional component of the coating liquid include antioxidants, fillers and the like.

Examples of the method for drying the surface to which the coating liquid is applied include a drying method using hot air and a drying method using infrared rays.

According to this embodiment, since the component (A) is present on one side or both sides, moldability and blocking resistance are further enhanced.
In addition, according to the present embodiment, the abundance of the component (B) is in a specific range on at least one of the surfaces where the component (A) is present. Therefore, the effect of the component (A) is not hindered by the component (B), and the moldability and blocking resistance can be further enhanced.

In the present embodiment, the non-foamed layer 20 is located only on one side of the foamed layer 10, but the present invention is not limited to this, and even if the non-foamed layer 20 is located on both sides of the foamed layer 10. Alternatively, the non-foamed layer 20 may not be provided on any surface of the foamed layer 10.

In the present embodiment, only the foamed layer 10 and the non-foamed layer 20 are provided, but the present invention is not limited to this, and the printing process is performed on both or one of the first surface 11 and the second surface 21 of the foamed sheet. May be applied. Alternatively, the surface of the non-foamed layer 20 facing the foamed layer 10 may be printed.
Further, the foamed sheet 1 may have an adhesive layer between the foamed layer 10 and the non-foamed layer 20.

(Polystyrene resin foam container)
The polystyrene-based resin foam container (foam container) of the present invention is formed by molding the above-mentioned foam sheet of the present invention.
Examples of the molded body include trays having a perfect circular shape, an elliptical shape, a semicircular shape, a polygonal shape, a fan shape, etc., a bowl-shaped container, a container having a bottomed cylindrical shape or a bottomed square cylinder shape, and a container for natto. Various containers such as containers with lids; lids and the like attached to the container body can be mentioned.
As the use of these containers, for example, food products are preferable.

An embodiment of the foam container of the present invention will be described with reference to the drawings.
The foam container 100 of FIG. 5 is a bowl-shaped container having a perfect circular shape in a plan view. The foam container 100 has a circular bottom wall 110 and a side wall 120 rising from the peripheral edge of the bottom wall 110. The side wall 120 extends outward toward the upper end.
The foam container 100 is formed with an opening 130 surrounded by the upper end of the side wall 120. The opening 130 surrounded by the upper end of the side wall 120 is a perfect circle in a plan view. The bottom wall 110 is formed of a convex portion 112 that is a perfect circle in a plan view and is convex in the direction of the opening 130, and an annular concave portion 114 that surrounds the convex portion 112.
The foam container 100 is suitably used as a container for foods such as storing instant noodles and pouring hot water into it.

The foam container 100 of the present embodiment is a perfect circle in a plan view, but the present invention is not limited to this. The plan-view shape of the foam container may be elliptical or polygonal.

The foam container 100 may have a non-foaming layer only on the inner surface, may have a non-foaming layer only on the outer surface, or may have a non-foaming layer on both the inner surface and the outer surface. Alternatively, the foam container 100 does not have to have a non-foam layer on either the inner surface or the outer surface.

The component (A) and optionally the component (B) are present on one side or both sides of the foam container 100. The surface on which the component (A) is present may be the inner surface of the foam container 100, the outer surface of the foam container 100, or both sides of the foam container 100.

The type and abundance of the component (A) in the foam container 100 are the same as the type and abundance of the component (A) in the foam sheet 1.
The type and abundance of the component (B) in the foam container 100 are the same as the type and abundance of the component (B) in the foam sheet 1.
The type and abundance of the surfactant other than the component (B) in the foam container 100 is the same as the type and the abundance of the surfactant other than the component (B) in the foam sheet 1.

(Manufacturing method of foam container)
Examples of the method for manufacturing a foam container include a method (thermoforming method) in which a foam sheet is heated to be softened (heating step) and then sandwiched between a female mold and a male mold to be molded (molding step).

The heating step is a step of heating and softening the foamed sheet. The heating temperature in the heating step may be any temperature as long as the foamed sheet softens, and is, for example, 80 to 150 ° C.

The molding step is a step of sandwiching a heated foam sheet between a female mold and a male mold to obtain a container having an arbitrary shape. At this time, since the foamed sheet of the present invention contains the component (A) and an arbitrarily specific amount of the component (B) on one side or both sides, the foamed sheet follows the inner surface shape of the female mold and the outer surface shape of the male mold. It is stretched and the moldability is further improved.
Examples of the molding method in the molding process include vacuum molding, pressure molding, free drawing molding, plug and ridge molding, ridge molding, matched molding, straight molding, drape molding, and reverse draw molding as applications thereof. , Air slip molding, plug assist molding, plug assist reverse load molding and the like, conventionally known thermal molding methods can be mentioned.
The temperature of the molding die in the molding step is not particularly limited, but is preferably 50 to 150 ° C, more preferably 60 to 130 ° C, for example. When the temperature of the molding mold is equal to or higher than the above lower limit value, the molding speed can be increased. When the temperature of the molding die is not more than the above upper limit value, it is possible to prevent the foamed sheet from melting.
After molding the foam sheet into a desired shape in the molding die, the mold is opened and the foam container portion is punched out from the foam sheet. Stack the punched foam containers and store them. In the stacked state, the bottom wall 110 of the upper foam container is in a state of being accepted in the opening 130. After storage, the foam containers are taken out one by one from the group of stacked foam containers, and the foam containers are filled with the contents. At this time, since the foam container of the present invention contains the component (A) and an arbitrarily specific amount of the component (B) on one side or both sides, the foam containers can be easily taken out one by one.

As described above, according to the foam container of the present invention, since the component (A) and an arbitrarily specific amount of the component (B) are present on one side or both sides, the foam container has higher moldability and blocking resistance. Be done.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the Examples.

(Raw materials used)
<Silicone emulsion>
S-1: Silicone emulsion, 33% by mass of dimethyl silicone oil, kinematic viscosity of silicone oil = 1000 mm ² / sec. .. As a surfactant, linear alkylbenzene sulfonate (carbon number of alkyl group = 10 to 14) (component (C)) is contained in 10.0 parts by mass with respect to 100 parts by mass of silicone oil.
S-2: Silicone emulsion, 40% by mass of dimethyl silicone, kinematic viscosity of silicone oil = 350 mm ² / sec. .. Does not contain surfactant.
S-3: Silicone emulsion, 35% by mass of dimethyl silicone, kinematic viscosity of silicone oil = 1000 mm ² / sec. .. As a surfactant, polyoxyalkylene alkyl (C12 to 15 of alkyl group) ether ((b1) component) is contained in an amount of 2.9 parts by mass with respect to 100 parts by mass of silicone oil, and a linear alkylbenzene sulfonate (alkyl group) is contained. Carbon number = 10 to 14) (component (C)) is contained in 2.9 parts by mass with respect to 100 parts by mass of silicone oil.
S-4: Silicone emulsion, 31% by mass of dimethyl silicone oil, kinematic viscosity of silicone oil = 1000 mm ² / sec. .. As a surfactant, polyoxyalkylene alkyl (alkyl group having 12 to 15 carbon atoms) ether (component (b1)) is contained in an amount of 4.8 parts by mass with respect to 100 parts by mass of silicone oil.
S-5: Silicone emulsion, 35% by mass of dimethyl silicone oil, kinematic viscosity of silicone oil = 10000 mm ² / sec. .. As a surfactant, coconut oil fatty acid diethanolamide ((b2) component) is contained in an amount of 2.9 parts by mass with respect to 100 parts by mass of silicone oil, and a linear alkylbenzene sulfonate (alkyl group C10-14) ((C). ) Component) is contained in 2.9 parts by mass with respect to 100 parts by mass of silicone oil.
S-6: Silicone emulsion, a mixture of 40 parts by mass of "S-1" and 60 parts by mass of "S-3". Silicone oil 34% by mass, silicone oil kinematic viscosity = 1000 mm ² / sec. .. As a surfactant, a polyoxyalkylene alkyl (alkyl group having 12 to 15 carbon atoms) ether ((b1) component) is contained in an amount of 1.8 parts by mass with respect to 100 parts by mass of silicone oil, and a linear alkylbenzene sulfonate (linear alkylbenzene sulfonate) ( C10-14) (component (C)) of the alkyl group is contained in an amount of 5.6 parts by mass with respect to 100 parts by mass of the silicone oil.
S-7: Silicone emulsion, a mixture of 70 parts by mass of "S-1" and 30 parts by mass of "S-3". Silicone oil 34% by mass, silicone oil kinematic viscosity = 1000 mm ² / sec. .. As a surfactant, a polyoxyalkylene alkyl (alkyl group having 12 to 15 carbon atoms) ether ((b1) component) is contained in an amount of 0.9 parts by mass with respect to 100 parts by mass of silicone oil, and a linear alkylbenzene sulfonate (straight-chain alkylbenzene sulfonate) ( The alkyl group C10-14) (component (C)) is contained in an amount of 7.7 parts by mass with respect to 100 parts by mass of the silicone oil.
-S-8: Silicone emulsion, a mixture of 40 parts by mass of "S-1" and 60 parts by mass of "S-5". Silicone oil 34% by mass, silicone oil kinematic viscosity = 6400 mm ² / sec. .. As a surfactant, 1.8 parts by mass of coconut oil fatty acid diethanolamide (component (b2)) is contained with respect to 100 parts by mass of silicone oil, and linear alkylbenzene sulfonate (alkyl group C10-14) ((C). ) Ingredients) is contained in an amount of 5.6 parts by mass with respect to 100 parts by mass of silicone oil.
S-9: Silicone emulsion, a mixture of 70 parts by mass of "S-1" and 30 parts by mass of "S-5". Silicone oil 34% by mass, silicone oil kinematic viscosity = 3700 mm ² / sec. .. As a surfactant, 0.9 parts by mass of coconut oil fatty acid diethanolamide (component (b2)) is contained with respect to 100 parts by mass of silicone oil, and linear alkylbenzene sulfonate (alkyl groups C10 to 14) ((C). ) Component) is contained in 7.7 parts by mass with respect to 100 parts by mass of silicone oil.

(Examples 1 to 17, Comparative Examples 1 to 5)
100 parts by mass of polystyrene resin (product name: HRM40 (manufactured by Toyo Styrene Co., Ltd.)) is mixed with a masterbatch product (DSM-1401A manufactured by Denki Styrol Co., Ltd.) equivalent to 0.7 parts by mass of powdered talc as a bubble conditioner. It was charged into the first extrusion section. 3.3 parts by mass of butane gas as a foaming agent was press-fitted into the first extruded part, and the resin and the foaming agent were mixed at 230 ° C. to obtain a foamable resin composition. Next, the temperature of the foamable resin composition was set to 160 ° C. in the second extrusion portion, and the foamable resin composition was extruded from the circular die to form the foam layer raw fabric, and the extruded foam layer raw fabric was formed. Cooling air (28 ° C.) was blown onto the outer surface to obtain a foam layer raw fabric ^{having a basis weight of 220 g / m 2 and a thickness of 1.8 mm.}
After aging the foam layer raw fabric for 20 days, impact-resistant polystyrene resin (product name: E641N (manufactured by Toyo Styrene Co., Ltd.)) is extruded on one side of the foam layer raw fabric with a T-die to provide a non-foamed layer with a thickness of 120 μm. , A laminate was obtained. Each of the silicone emulsions shown in Tables 1 to 3 was diluted with water to a mass ratio of 11 times (silicone emulsion: water = 1:10) to prepare a coating liquid. While winding the obtained laminate, immediately before winding, a coating liquid was applied to the surface described in the table with a silicone coating device (manufactured by Nikka Co., Ltd.) and dried to obtain a foamed sheet of each example. The coating amount of the coating liquid was 0.4 g / m ² .
The obtained foam sheet was evaluated for moldability and blocking resistance, and the results are shown in the table. Examples 1 to 5 and 10 to 17 are reference examples.

(Example 18)
A foamed sheet was obtained in the same manner as in Example 1 except that the non-foaming layer was not provided and the coating liquid was applied to only one side.
The obtained foam sheet was evaluated for moldability and blocking resistance, and the results are shown in the table. Example 18 is a reference example.

(Evaluation method)
<Moldability>
≪Evaluation of moldability at standard temperature≫
The foamed sheet of each example was left to stand at 27 ± 3 ° C. and a relative humidity of 60 ± 5% for 24 hours, and then a flat rectangular test piece having a length of 700 mm and a width of 1040 mm was cut out from the foamed sheet.
Next, using a single-shot molding machine (manufactured by Tosei Sangyo Co., Ltd., trade name "FM-3A"), the average temperature of the upper heater of this single-shot molding machine was set to 270 ° C, the average temperature of the lower heater was set to 220 ° C, and the atmosphere. The temperature was 155 ° C.
Next, the test piece was introduced into a single-shot molding machine and heated for 17 seconds, and then 18 foam containers having an opening at the top were prepared for each example by thermoforming. Regarding the container shape, in Examples 1 to 15 and 18 and Comparative Examples 1 to 5, an inverted quadrangular pyramid-shaped foam container having a non-foaming layer on the inner surface of the container and having a square bottom surface (opening 150 mm). × 150 mm, bottom surface 110 mm × 110 mm, height 60 mm) was produced.
In Examples 16 and 17, inverted truncated cone-shaped foam containers (opening diameter 140 mm, bottom diameter 100 mm, height 70 mm) having a non-foam layer on the outer surface of the container were prepared. The obtained container was visually inspected and the moldability was evaluated according to the following criteria.

[Evaluation criteria]
-A: All 18 pieces were well formed.
-B: Some containers had slight wrinkles, but there were no cracks.
-C: Cracks were found in some containers.
-D: Cracks and wrinkles were found in all containers.

≪Evaluation of moldability under low temperature conditions≫
The moldability was evaluated in the same manner as in the above-mentioned "evaluation of moldability at standard temperature" except that the test piece was introduced into a single-shot molding machine, heated for 15 seconds, and then thermoformed.

≪Evaluation of moldability under high temperature conditions≫
The moldability was evaluated in the same manner as in the above-mentioned "evaluation of moldability at standard temperature" except that the test piece was introduced into a single-shot molding machine, heated for 19 seconds, and then thermoformed.

<Blocking resistance>
When 18 containers obtained in "Evaluation of moldability at standard temperature" are fitted to each other in the vertical direction and overlapped with each other, cured at 23 ° C. for 48 hours, and then the containers are separated from each other. Resistance was evaluated based on the following criteria.

≪Evaluation criteria≫
-A: The containers could be easily separated from each other without resistance, and even if the stacked containers were pushed in from above, they could be easily separated.
-B: The containers could be separated from each other, but it was difficult to push the stacked containers from above and try to separate them due to resistance.
-C: It was difficult to separate the containers due to resistance.

<Comprehensive evaluation>
Evaluation was made based on the following criteria.
≪Evaluation criteria≫
-A: All item evaluations were "A".
-B: All item evaluations were "A" or "B", and there was one or more "B".
-C: All item evaluations were "A", "B" or "C", and there was one "C".
-D: There was "C" or "D" in the evaluation, and the total of "C" and "D" was two or more.

As shown in Tables 1 to 3, the overall evaluations of Examples 1 to 18 to which the present invention was applied were "A" to "C".
Comparative Examples 1 to 3 in which the abundance of the component (B) is outside the range of the present invention on both the non-foamed layer surface and the foamed layer surface, the component (A) is present on only one side, and the component (B) on that surface is present. Comparative Example 4 in which the abundance amount was outside the range of the present invention and Comparative Example 5 in which no silicone oil was present on any surface had a comprehensive evaluation of "D".
From these results, it was found that the moldability and blocking resistance can be further improved by applying the present invention.

1 Foam sheet 10 Foam layer 11 First surface 20 Non-foam layer 21 Second surface

Claims (9)

In a polystyrene resin foam sheet having a foam layer containing a polystyrene resin,
Silicone oil (A) and at least one surfactant (B) optionally selected from polyoxyethylene alkyl ether (b1) and coconut oil fatty acid diethanolamide (b2) are present on one or both sides.
The abundance of the surfactant (B) is 2.5 parts by mass or less with respect to 100 parts by mass of the silicone oil (A).
The surfactant (B) is present on one side or both sides, and the surfactant (B) is present.
In terms of the presence of the surfactant (B), the polystyrene-based resin foam sheet has an abundance of the surfactant (B) of 40 parts by mass or less with respect to 100 parts by mass of the total amount of the surfactant. The polystyrene-based resin foam sheet according to claim 1, wherein the abundance of the silicone oil (A) is 0.001 to 0.20 g / m ^2. The kinematic viscosity of the silicone oil (A) is 2000 mm ² / sec. The polystyrene-based resin foam sheet according to claim 1 or 2, which is less than or equal to. The polystyrene-based resin foam sheet according to any one of claims 1 to 3, which has a non-foamed layer of a thermoplastic resin on one side or both sides of the foamed layer. In a polystyrene resin foam container having a foam layer containing a polystyrene resin,
Silicone oil (A) and at least one surfactant (B) optionally selected from polyoxyethylene alkyl ether (b1) and coconut oil fatty acid diethanolamide (b2) are present on one or both sides.
The abundance of the surfactant (B) is 2.5 parts by mass or less with respect to 100 parts by mass of the silicone oil (A).
The surfactant (B) is present on one side or both sides, and the surfactant (B) is present.
A polystyrene-based resin foam container in which the abundance of the surfactant (B) is 40 parts by mass or less with respect to 100 parts by mass of the total amount of the surfactant in terms of the presence of the surfactant (B). The polystyrene-based resin foam container according to claim 5, wherein the abundance of the silicone oil (A) is 0.001 to 0.20 g / m ^2. The kinematic viscosity of the silicone oil (A) is 2000 mm ² / sec. The polystyrene-based resin foam container according to claim 5 or 6, which is less than. The polystyrene-based resin foam container according to any one of claims 5 to 7, which has a non-foamed layer of a thermoplastic resin on one side or both sides of the foamed layer. The polystyrene-based resin foam container according to any one of claims 5 to 8, which is for food use.

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