JP7352500B2 - Thermoplastic polyester resin laminated foam sheet and thermoplastic polyester resin laminated foam container - Google Patents

Description

The present invention relates to a thermoplastic polyester resin laminated foam sheet and a thermoplastic polyester resin laminated foam container.

It is known that a container (thermoplastic polyester resin laminated foam container) formed by molding a thermoplastic polyester resin laminated foam sheet (hereinafter also simply referred to as a "laminated foam sheet") has excellent heat resistance. For this reason, thermoplastic polyester resin laminated foam containers are widely used as containers for cooked foods that are heated in microwave ovens or ovens.
For example, there are cooked foods in containers in which cooked foods are placed in thermoplastic polyester resin laminated foam containers.

Prepared foods packaged in containers include products that are transported refrigerated or frozen. Such products include so-called frozen foods. Further, for example, ready-to-eat food packaged in containers that are transported in a refrigerated or frozen state includes products that are manufactured in a central kitchen or the like and transported to a store or the like in a refrigerated or frozen state. These packaged cooked foods are heated in a microwave oven, steam convection oven, etc. in a packaged state when consumed by a consumer or processed at a store. In this way, cooked foods packed in containers do not require refilling of containers, and operations such as cooking are simple.

When transporting container-packed cooked food in a refrigerated or frozen state, there is a problem in that if the container-packed cooked food receives a physical impact, such as by falling, during the transportation process, the container may be damaged. That is, thermoplastic polyester resin laminated foam containers have problems in that they are brittle at low temperatures (high low-temperature brittleness) and have low impact strength in low-temperature environments (low cold resistance).
To address these problems, food containers have been proposed that are made from a composite sheet in which a polyester resin sheet is laminated via a polyolefin resin or a thermoplastic resin containing rubber. Patent Document 1). According to the invention of Patent Document 1, the occurrence of cracks is reduced by using a specific layer configuration.
Furthermore, a food container has been proposed that is made of a composite sheet made by laminating a non-foamed film of thermoplastic resin on at least one side of a foamed sheet of thermoplastic polyester resin, and is formed with the non-foamed film facing inward ( Patent Document 2). According to the invention described in Patent Document 2, heat resistance, heat insulation properties, and impact resistance are improved.

Japanese Patent Application Publication No. 10-278918 Japanese Patent Application Publication No. 03-111244

However, conventional techniques still do not have sufficient cold resistance. In addition, thermoplastic polyester resin laminated foam containers are required to have little deterioration in quality due to heating (high heat resistance).
Therefore, the object of the present invention is to provide a thermoplastic polyester resin laminated foam sheet and a thermoplastic polyester resin laminated foam container that have excellent heat resistance and further improve cold resistance.

<1> Comprising a foamed layer of thermoplastic polyester resin and a non-foamed layer provided on at least one surface of the foamed layer,
Among the one or more absorbed energy peaks measured by a heat flux differential scanning calorimeter when the temperature is raised from 30° C. to 290° C., the lowest absorbed energy peak is 170° C. or higher,
The total absorbed energy in the Dynatap impact test at -20°C is 0.15 J or more,
The dimensional change rate at 200°C determined by the following measurement method is less than 10%,
Thermoplastic polyester resin laminated foam sheet.
<Measurement method>
A thermoplastic polyester resin laminated foam sheet measuring 50 mm in the MD direction and 50 mm in the TD direction is heated in a heating furnace at 200°C for 10 minutes, and the length L _m1 in the MD direction and the length L _t1 in the TD direction of one surface and the other surface are determined. The length L _m2 in the MD direction and the length L _t2 in the TD direction are measured, and the average value of [Length L _m1 ] and [Length L _m2 ] is taken as the average value of the length in the MD direction, and [Length L _t1 ] and [Length L _t2 ] as the average value of the length in the TD direction, and among the absolute values of the amount of dimensional change calculated by the following formula (s0), the larger value is determined as "after heating". The dimensional change value (α1) mm" and the value calculated by the following formula (s1) are defined as the dimensional change rate (%).
Amount of dimensional change (mm) = [Dimension of one side before heating: 50 mm] - [Average value of length in MD direction or TD direction after heating] ... (s0)
Dimensional change rate (%) = [Dimension change value after heating (α1) mm] ÷ [Dimension of one side before heating: 50 mm] × 100 ... (s1)
<2> The thermoplastic polyester resin laminated foam sheet according to <1>, wherein the non-foamed layer is a non-stretched film.
<3> The non-foaming layer is made of polyamide, polybutylene terephthalate (PBT), amorphous polyethylene terephthalate (PET-G), poly(1,4-cyclohexylene dimethylene terephthalate) copolyester resin, polycyclohexylene terephthalate The item described in <1> or <2> contains at least one member selected from the group consisting of methylene terephthalate (PCT-G), acid-modified polycyclohexylene dimethylene terephthalate (PCT-A), and ethylene vinyl alcohol resin (EVOH). thermoplastic polyester resin laminated foam sheet.
<4> The thermoplastic polyester resin laminated foam sheet according to any one of <1> to <3>, which has two or more of the absorption energy peaks.
<5> The thermoplastic polyester resin laminated foam sheet according to any one of <1> to <4>, which has two or more of the absorption energy peaks, and the absorption energy peak on the low temperature side is 200° C. or higher.
<6> The thermoplastic polyester resin laminated foam sheet according to any one of <1> to <5>, wherein the foam layer has a basis weight of 200 to 1000 g/m ² .
<7> The thermoplastic polyester resin laminated foam sheet according to any one of <1> to <6>, having a thickness of 0.2 to 3 mm.
<8> The thermoplastic polyester resin laminated foam sheet according to any one of <1> to <7>, wherein the Z-average molecular weight Mz of the foam layer is 100,000 to 500,000.

<9> In a thermoplastic polyester resin laminated foam container having a bottom wall portion and a side wall portion rising from the periphery of the bottom wall portion,
It has a foamed layer of thermoplastic polyester resin and a non-foamed layer provided on at least one surface of the foamed layer,
Among the one or more absorbed energy peaks measured by a heat flux differential scanning calorimeter when the temperature is raised from 30° C. to 290° C., the lowest absorbed energy peak is 170° C. or higher,
The total absorbed energy in the Dynatap impact test at -20°C is 0.15 J or more,
The dimensional change rate at 200°C determined by the following measurement method is less than 10%,
Thermoplastic polyester resin laminated foam container.
<Measurement method>
Cut out a 50 mm square section from the bottom wall of the thermoplastic polyester resin laminated foam container, heat this section in a heating furnace at 200° C. for 10 minutes, and measure the length L _d1 along any side on one surface. Measure the length L _d2 in the direction perpendicular to the arbitrary side, the length L _d11 in the direction along the arbitrary side on the other surface, and the length L _d12 in the direction perpendicular to the arbitrary side, The average value of [Length L _d1 ] and [Length L _d11 ] is the average value of the length in the direction along the arbitrary side, and the average value of [Length L _d2 ] and [Length L _d12 ] is the average value of the length in the direction perpendicular to the above arbitrary side, and among the absolute values of the dimensional change amount calculated by the following formula (s2), the larger value is the ``dimensional change value after heating (α2)''mm", and the value calculated by the following formula (s3) is taken as the dimensional change rate (%).
Amount of dimensional change (mm) = [Dimension of one side before heating: 50 mm] - [Average value of the length in the direction along the arbitrary side or in the direction perpendicular to the arbitrary side after heating] ... (s2 )
Dimensional change rate (%) = [Dimension change value after heating (α2) mm] ÷ [Dimension of one side before heating: 50 mm] × 100 ... (s3)
<10> The thermoplastic polyester resin laminated foam container according to <9>, wherein the non-foamed layer is a non-stretched film.
<11> The non-foaming layer is made of polyamide, polybutylene terephthalate (PBT), amorphous polyethylene terephthalate (PET-G), poly(1,4-cyclohexylene dimethylene terephthalate) copolyester resin, polycyclohexylene terephthalate The item described in <9> or <10> contains at least one member selected from the group consisting of methylene terephthalate (PCT-G), acid-modified polycyclohexylene dimethylene terephthalate (PCT-A), and ethylene vinyl alcohol resin (EVOH). Thermoplastic polyester resin laminated foam container.
<12> The thermoplastic polyester resin laminated foam container according to any one of <9> to <11>, which has two or more of the absorption energy peaks.
<13> The thermoplastic polyester resin laminated foam container according to any one of <9> to <12>, which has two or more of the absorption energy peaks, and the absorption energy peak on the low temperature side is 200° C. or higher.
<14> The thermoplastic polyester resin laminated foam container according to any one of <9> to <13>, wherein the foam layer has a basis weight of 200 to 1000 g/m ² .
<15> The thermoplastic polyester system according to any one of <9> to <14>, wherein the bottom wall portion has a thickness of 0.2 to 3 mm, and the bottom side portion has a thickness of 0.2 to 3 mm. Resin laminated foam container.
<16> The thermoplastic polyester resin laminated foam container according to any one of <9> to <15>, wherein the foam layer has a Z-average molecular weight Mz of 100,000 to 500,000.
<17> The thermoplastic polyester resin laminated foam container according to any one of <9> to <16>, wherein the foam layer has a crystallinity of 15% or more and 30% or less.
<18> The thermoplastic polyester resin laminated foam container according to any one of <9> to <17>, which is for food use.
<19> The thermoplastic polyester resin laminated foam container according to <18>, which is for refrigerated food or frozen food.

According to the thermoplastic polyester resin laminated foam sheet and the thermoplastic polyester resin laminated foam container of the present invention, the heat resistance is excellent and the cold resistance can be further improved.

1 is a cross-sectional view showing an example of a thermoplastic polyester resin laminated foam sheet of the present invention. It is a flow diagram showing an example of a manufacturing process of a plant-derived polyester resin. It is a flow diagram showing an example of a manufacturing process of a plant-derived polyester resin. It is a flow diagram showing an example of a manufacturing process of a plant-derived polyester resin. This is an example of a DSC chart of a thermoplastic polyester resin laminated foam container.

(Thermoplastic polyester resin laminated foam sheet)
The thermoplastic polyester resin laminated foamed sheet (laminated foamed sheet) of the present invention has a foamed layer of thermoplastic polyester resin and a non-foamed layer provided on at least one surface of the foamed layer.
In the foamed sheet, the non-foamed layer may be provided on one side of the foamed layer, or may be provided on both sides of the foamed layer.

A laminated foam sheet according to an embodiment of the present invention will be described with reference to FIG. 1.
The laminated foam sheet 1 in FIG. 1 has a foam layer 10 and a non-foam layer 20 provided on one surface of the foam layer 10.
The thickness T of the laminated foam sheet 1 is, for example, preferably 0.2 to 3 mm, more preferably 0.5 to 2 mm. If the thickness T is greater than or equal to the above lower limit, the strength of the resulting container can be increased. If the thickness T is below the above upper limit, it is easy to mold the container.
Note that the thickness T is determined by the following method. The thickness of the laminated foam sheet 1 at ten arbitrary points in the TD direction is measured using a thickness gauge. The thickness T of the laminated foam sheet 1 is determined by averaging the measured values at 10 points.

<Physical properties>
In the laminated foam sheet 1, among the absorbed energy peaks (DSC peaks) measured by a heat flux differential scanning calorimetry (DSC) device when the temperature is raised from 30°C to 290°C, the DSC peak on the lowest temperature side (lowest temperature side DSC peak) is 170°C or higher, preferably 190°C or higher, and more preferably 200°C or higher. If the low-temperature side DSC peak is equal to or higher than the above lower limit, cold resistance can be further improved. The upper limit of the low temperature side DSC peak is substantially 290°C.
The temperature of the low-temperature side DSC peak can be adjusted by the combination of the material of the foamed layer 10 and the material of the non-foamed layer 20.

It is preferable that the laminated foam sheet 1 has two or more DSC peaks. By having two or more DSC peaks (that is, having at least one DSC peak on the high temperature side rather than the low temperature side DSC peak), heat resistance can be further improved.
When the laminated foam sheet 1 has two or more DSC peaks, the DSC peaks other than the low-temperature side DSC peak (other DSC peaks) are preferably 190°C or higher, more preferably 200°C or higher, and even more preferably 220°C or higher.
The difference between the low-temperature side DSC peak and other DSC peaks is preferably 10 to 80°C, more preferably 20 to 70°C, and even more preferably 25 to 60°C.

In the laminated foam sheet 1, the total absorbed energy in the Dynatap impact test at -20°C (-20°C total absorbed energy) is 0.15 J or more, preferably 0.20 J or more. If the total absorbed energy at -20°C is greater than or equal to the above lower limit, cold resistance can be further enhanced. The upper limit of the -20°C total absorbed energy is substantially 5.0 J or less.
Note that the -20°C total absorbed energy of the laminated foam sheet 1 is the average value of the -20°C total absorbed energy of both sides of the laminated foam sheet 1.
The -20°C total absorbed energy can be adjusted by combining the material, density or thickness of the foam layer 10, the material or thickness of the non-foam layer 20, and the like.

The DynaTap impact test is conducted in accordance with ASTM D-3763 “Standard Test Method for High Speed Puncture Properties.
of Plastics Using Load and Displacement
It is measured according to "Sensors".
The DynaTap impact test in this paper is explained below. The laminated foam sheet was cut into 10 cm square pieces from five points in the TD direction, and these pieces were cured for 16 hours in an environment of -20°C to obtain test pieces.
The test piece is measured according to the test conditions below, and the integral value of the obtained graph is automatically calculated by the test device, and is defined as the total absorbed energy.

≪Test conditions, etc.≫
- Test device: Dynatap impact test device GRC 8250 (manufactured by General Research Corp.).
- Test piece: 100 x 100 x original thickness (mm).
・Span: Round hole inner diameter 76mm.
-Test speed: 1.52m/s.
-Test temperature: -20℃.
- Drop height (stopper position): 56cm.
- Falling weight distance: 12cm.
-Test load: 3.17kg.
・Number of tests: 5.

The dimensional change rate of the laminated foam sheet 1 at 200° C. is less than 10%, more preferably less than 7%, and even more preferably less than 5%. If the dimensional change rate at 200°C is less than the above upper limit, heat resistance can be further improved.

A method for measuring the dimensional change rate at 200°C will be explained.
A square section measuring 50 mm in the MD direction and 50 mm in the TD direction is cut out from the laminated foam sheet 1. The cut sections are heated in a heating oven at 200° C. for 10 minutes. Regarding the heated section, the length L _m1 in the MD direction and the length L _t1 in the TD direction of one surface, and the length L _m2 in the MD direction and the length L _t2 in the TD direction of the other surface are measured. Let the average value of [length L _m1 ] and [length L _m2 ] be the average value of the length in the MD direction. Let the average value of [length L _t1 ] and [length L _t2 ] be the average value of the length in the TD direction. The amount of dimensional change is calculated using the following formula (s0).
Amount of dimensional change (mm) = [Dimension of one side before heating: 50 mm] - [Average value of length in MD direction or TD direction after heating] ... (s0)
Among the absolute values of the calculated dimensional change amounts, the larger numerical value is defined as the "dimensional change value after heating (α1) mm." The dimensional change rate (%) is calculated using the following formula (s1).

Dimensional change rate (%) = [Dimension change value after heating (α1) mm] ÷ [Dimension of one side before heating: 50 mm] × 100 ... (s1)
Note that the lengths of the line segments passing through the center of the square of the cut section are respectively [length L _m1 ], [length L _m2 ], [length L _t1 ], and [length L _t2 ], and the section is curved. In this case, the lengths of the line segments along the curved surface are respectively set as [length L _m1 ], [length L _m2 ], [length L _t1 ], and [length L _t2 ].
The dimensional change rate at 200° C. can be adjusted by a combination of the material, density or thickness of the foamed layer 10, the material or thickness of the non-foamed layer 20, and the like.

<Foam layer>
The thickness of the foam layer 10 is preferably 0.1 to 5 mm, more preferably 0.2 to 4 mm, even more preferably 0.3 to 3 mm, and particularly preferably 0.4 to 2 mm. If it is more than the above lower limit, the strength of the thermoplastic polyester resin laminated foam container (hereinafter sometimes referred to as "foam container") described later can be further increased. If it is below the above upper limit, it is easy to sufficiently heat the inside of the laminated foam sheet during container molding.
Note that the thickness T1 is determined by the following method. The thickness of the foamed layer 10 at ten arbitrary points in the TD direction is measured using a thickness gauge. The measured values at 10 points are averaged to determine the thickness T1 of the foamed layer 10.

The basis weight of the foamed layer 10 is preferably 200 to 1000 g/m ² , more preferably 250 to 900 g/m ² , even more preferably 300 to 800 g/m ² . If it is at least the above lower limit, the strength of the foaming container can be further increased. If it is below the above upper limit, it will be easier to mold the foam container.

The foaming ratio of the foam layer 10 is preferably 1.5 to 15 times, more preferably 2 to 10 times, even more preferably 2 to 8 times. If it is more than the above lower limit, the heat insulation properties of the foaming container can be further improved. If it is below the above upper limit, it is easy to sufficiently heat the inside of the laminated foam sheet during molding of a foam container. The "foaming ratio of the foam layer" is the value obtained by dividing 1 by the "apparent density of the foam layer".

The average cell diameter of the foamed layer 10 is preferably, for example, 80 to 1000 μm. The average cell diameter of the foam layer 10 is measured according to the method described in ASTM D2842-69.

The closed cell ratio of the foam layer 10 is preferably 50% or more, more preferably 60% or more, even more preferably 70% or more, particularly preferably 80% or more, and may be 90% or more. The closed cell ratio of the foam layer 10 is measured by the method described in JIS K7138:2006 "Rigid foamed plastics - How to determine open cell ratio and closed cell ratio".

≪Polyester resin≫
Polyester resins include polyethylene terephthalate resin (PET), polybutylene terephthalate resin, polyethylene naphthalate resin, polyethylene furanoate resin (PEF), polybutylene naphthalate resin, polytrimethylene terephthalate resin (PTT), terephthalic acid and ethylene. Examples include copolymers of glycol and cyclohexanedimethanol, mixtures thereof, and mixtures of these and other resins. Furthermore, plant-derived polyethylene terephthalate resin, plant-derived polyethylene furanoate resin, and plant-derived polytrimethylene terephthalate resin may be used. These polyester resins may be used alone or in combination of two or more. Among polyester resins, polyethylene terephthalate resin is preferred, and crystalline polyethylene terephthalate resin (A-PET) is more preferred. A-PET is a polyester resin whose acid component is terephthalic acid and whose glycol component is ethylene glycol.

The polyester resin may be a plant-derived polyester resin such as so-called bio-PET.
Plant-derived polyester resins are polymers derived from plant materials such as sugarcane and corn. "Derived from plant materials" includes polymers synthesized or extracted from plant materials. Further, for example, "derived from a plant material" includes a polymer obtained by polymerizing a monomer synthesized or extracted from a plant material. "Monomers synthesized or extracted from plant materials" include monomers synthesized using compounds synthesized or extracted from plant materials as raw materials. Plant-derived polyester resins include those in which some of the monomers are "derived from plant materials."

Plant-derived polyester resins will be explained using PET and PEF as examples.

The synthesis reaction of PET is shown in equation (1). PET is synthesized by a dehydration reaction between n moles of ethylene glycol and n moles of terephthalic acid (Benzen-1,4-dicarboxylic acid). The stoichiometric mass ratio in this synthesis reaction is ethylene glycol:terephthalic acid=30:70 (mass ratio).

［（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 formula (1), n is a stoichiometric coefficient (degree of polymerization), and is a number from 250 to 1100. ]

Ethylene glycol is produced industrially by oxidizing and hydrating ethylene. Terephthalic acid is also produced industrially by oxidizing paraxylene.
As shown in Figure 2, ethylene is obtained through the dehydration reaction of plant-derived ethanol (bioethanol), and ethylene glycol synthesized from this ethylene (ethylene glycol derived from bioethanol) and terephthalate derived from petrochemicals are produced. When PET is synthesized from acid, the PET produced is 30% by mass PET derived from plants.
Additionally, as shown in Figure 3, paraxylene is obtained through the 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 PET derived from plants.

The synthesis reaction of PEF is shown in equation (2). PEF is synthesized by a dehydration reaction between n moles of ethylene glycol and n moles of 2,5-Furandicarboxylic acid.

［（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 formula (2), n is the stoichiometric coefficient (degree of polymerization), and is a number from 250 to 1100. ]

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

When the polyester resin contains the other resin, the content of the other resin is preferably less than 50% by mass, more preferably less than 30% by mass, and less than 10% by mass based on the total mass of the polyester resin. More preferred.

The number average molecular weight Mn of the polyester resin of the foam layer 10 is 9,000 to 26,000, preferably 15,000 to 26,000, and more preferably 20,000 to 25,000.
If Mn is at least the above lower limit, cold resistance can be further improved. If Mn is below the above upper limit, heat resistance can be further improved.

The Z average molecular weight Mz of the polyester resin of the foam layer 10 is 100,000 to 500,000, preferably 150,000 to 450,00, and more preferably 200,000 to 400,000.
If Mz is within the above range, cold resistance can be further improved.

Mn and Mz can be measured by the following method.
[Molecular weight of polyester resin]
Take 5 mg of a sample from the measurement target, add 0.5 mL of hexafluoroisopropanol (HFIP) and 0.5 mL of chloroform in this order, and shake gently manually. This was left for a soaking time of 24±1.0 hr. After confirming that the sample is completely dissolved, dilute to 10 mL with chloroform and mix by gently shaking manually. Thereafter, the sample is filtered using a non-aqueous 0.45 μm chromatographic disk manufactured by GL Sciences, Inc. or a non-aqueous 0.45 μm syringe filter manufactured by Shimadzu GLC, Inc. to obtain a measurement sample. The measurement sample is measured using a chromatograph under the following measurement conditions, and the number average molecular weight Mn and Z average molecular weight Mz of the sample are determined from a standard polystyrene calibration curve prepared in advance.

〔measuring device〕
- Measuring device = manufactured by Tosoh Corporation, "HLC-8320GPC EcoSEC", gel permeation chromatograph (with built-in RI detector and UV detector).
[GPC measurement conditions]
・Column (sample side)
Guard column = TSK guardcolumn HXL-H (6.0 mm x 4.0 cm) manufactured by Tosoh Corporation x 1.
Measurement column = 2 TSKgel GMHXL (7.8 mm I.D. x 30 cm) manufactured by Tosoh Corporation in series.
<Reference side>
2 resistance tubes (inner diameter 0.1mm x 2m) in series.
Column temperature = 40°C.
Mobile phase = chloroform.
<Dynamic phase flow rate>
Sample side pump = 1.0 mL/min.
Reference side pump = 0.5 mL/min.
Detector = UV detector (254 nm).
Injection volume = 15 μL.
Measurement time = 26 minutes.
Sampling pitch = 500ms.

[Standard polystyrene sample for calibration curve]
The standard polystyrene samples for the calibration curve have mass average molecular weights Mw of 5,620,000, 3,120,000, and 1 from the product names "STANDARD SM-105" and "STANDARD SH-75" manufactured by Showa Denko K.K. , 250,000, 442,000, 131,000, 54,000, 20,000, 7,590, 3,450, and 1,320.
The standard polystyrene for the above calibration curve is 7,590, 1,320). After weighing A (2 mg, 3 mg, 4 mg, 4 mg, 4 mg), dissolve it in 30 mL of chloroform. After weighing B (3 mg, 4 mg, 4 mg, 4 mg, 4 mg), dissolve it in 30 mL of chloroform.
The standard polystyrene calibration curve is obtained by injecting 50 μL of each of the prepared solutions A and B and creating a calibration curve (cubic equation) from the retention times obtained after measurement. The number average molecular weight Mn and the Z average molecular weight Mz are calculated using the calibration curve.

The intrinsic viscosity (IV value) of the raw material polyester resin is preferably 0.50 to 1.50, more preferably 0.80 to 1.10. If the IV value is greater than or equal to the above lower limit, foaming will occur more easily and a foamed layer will be more easily obtained. If the IV value is below the above upper limit, a smooth sheet can be easily obtained.
The IV value can be measured by the method of JIS K7367-5 (2000).

<Foaming agent>
Examples of the blowing agent include saturated aliphatic hydrocarbons such as propane, normal butane, isobutane, normal pentane, isopentane, and hexane, ethers such as dimethyl ether, methyl chloride, 1,1,1,2-tetrafluoroethane, 1 , 1-difluoroethane, monochlorodifluoromethane, carbon dioxide, nitrogen, etc., with dimethyl ether, propane, n-butane, isobutane, carbon dioxide, and nitrogen being preferred. These blowing agents may be used alone or in combination of two or more.

The content of the blowing agent is not particularly limited, but is preferably, for example, 0.1 to 12 parts by mass based on 100 parts by mass of the polyester resin.

<Optional ingredients>
The laminated foam sheet of the present invention may contain other components (optional components) in addition to the polyester resin, crystallization promoter, and foaming agent.
Examples of such optional components include cell regulators, stabilizers, ultraviolet absorbers, colorants, crystallization promoters, lubricants, crosslinking agents, surfactants, anti-shrinkage agents, flame retardants, anti-deterioration agents, and the like.
Note that the total amount of the polyester resin, blowing agent, and optional components does not exceed 100% by mass.

Examples of the crosslinking agent include acid dianhydrides such as pyromellitic anhydride, polyfunctional epoxy compounds, oxazoline compounds, and oxazine compounds.
The content of the crosslinking agent is preferably, for example, 0.08 to 0.5 parts by weight based on 100 parts by weight of the polyester resin.

The bubble control agent is, for example, a mixture of inorganic powders such as talc and silica. These cell regulators increase the closed cell ratio of the foamed layer 10, making it easier to form the foamed layer 10.
The content of the cell regulator is preferably, for example, 0.2 to 5 parts by weight based on 100 parts by weight of the polyester resin.

Examples of the stabilizer include a calcium-zinc heat stabilizer, a tin-based heat stabilizer, and a lead-based heat stabilizer.
The content of the stabilizer is preferably 1 part by mass or less, for example, based on 100 parts by mass of the polyester resin.

Examples of the ultraviolet absorber include a cesium oxide-based ultraviolet absorber and a titanium oxide-based ultraviolet absorber.
The content of the ultraviolet absorber is preferably, for example, 1 part by mass or less per 100 parts by mass of the polyester resin.

Examples of the antioxidant include cerium oxide, cerium oxide/zirconia solid solution, cerium hydroxide, carbon, carbon nanotubes, titanium oxide, and fullerene.
The content of the antioxidant is preferably, for example, 1 part by mass or less based on 100 parts by mass of the polyester resin.

Examples of the coloring agent include titanium oxide, carbon black, titanium yellow, iron oxide, ultramarine blue, cobalt blue, fired pigment, metallic pigment, mica, pearl pigment, zinc white, precipitated silica, and cadmium red.
When the laminated foam sheet of the present invention is used for manufacturing foam containers for food, it is preferable to select a Sanitary Council-registered coloring agent from among the above-mentioned colorants.
The content of the colorant is preferably 2 parts by mass or less, for example, based on 100 parts by mass of the polyester resin.

Examples of crystallization promoters include silicates, carbon, and metal oxides. Examples of silicates include talc, which is hydrous magnesium silicate. Examples of carbon include carbon black, carbon nanofibers, carbon nanotubes, carbon nanohorns, activated carbon, graphite, graphene, coke, mesoporous carbon, glassy carbon, hard carbon, and soft carbon. Examples include black, acetylene black, Ketjen black, and thermal black. Examples of metal oxides include zinc oxide and titanium oxide.
The content of the crystallization promoter is preferably 3 parts by mass or less, for example, based on 100 parts by mass of the polyester resin.

The above-mentioned optional components may be used alone or in combination of two or more.
The total amount of optional components contained in the foamed layer 10 is preferably 0.1 to 5 parts by mass, more preferably 0.5 to 3 parts by mass, based on the total mass of the foamed layer 10.

<Non-foamed layer>
The non-foamed layer 20 is preferably a non-stretched film, for example. If the non-foamed layer 20 is an unstretched film, it is easy to increase the total absorbed energy in the Dynatap impact test at -20°C, and it is easy to reduce the dimensional change rate at 200°C.
Examples of the material for the non-foamed layer 20 include polyamide, polybutylene terephthalate (PBT), amorphous polyethylene terephthalate (PET-G), poly(1,4-cyclohexylene dimethylene terephthalate) copolyester resin, and polycyclocarbonate. Examples include xylene dimethylene terephthalate (PCT-G), acid-modified polycyclohexylene dimethylene terephthalate (PCT-A), ethylene vinyl alcohol resin (EVOH), polyamide, PBT, PET-G, poly(1,4-cyclo Hexylene dimethylene terephthalate) copolyester resin and PCT-A are preferred, polyamide and PCT-A are more preferred, and polyamide is even more preferred. Among these, an unstretched polyamide film is particularly suitable as the non-foamed layer 20.
Examples of the polyamide include nylon 4, nylon 6, nylon 11, nylon 12, and nylon 66. As the polyamide, either nylon 4 or nylon 6 is preferred, and nylon 6 is more preferred.
Here, PET-G is a copolyester resin containing terephthalic acid as an acid component and ethylene glycol and 1,4-cyclohexanedimethanol (CHDM) as glycol components, and is represented by the following formula (3).

［（３）式中、ｐ、ｑは重合度であり、２５０～１１００の数であり、ｐ＞ｑある。］

[In the formula (3), p and q are the degree of polymerization, and are numbers from 250 to 1100, and p>q. ]

Poly(1,4-cyclohexylene dimethylene terephthalate) copolyester resin contains terephthalic acid as an acid component and 1,4-cyclohexanedimethanol (CHDM) and 2,2,4,4-tetramethyl as glycol components. It is a copolyester resin containing cyclobutanediol (TMCD), and is represented by the following formula (4).

［（４）式中、ｘ、ｙは重合度であり、２５０～１１００の数である。］

[In the formula (4), x and y are the degree of polymerization, and are numbers from 250 to 1100. ]

PCT-G is a copolyester resin containing terephthalic acid as an acid component and ethylene glycol and CHDM as glycol components, and is represented by the following formula (5).

［（５）式中、ｐ、ｑは重合度であり、２５０～１１００の数であり、ｐ＜ｑある。］

[In the formula (5), p and q are the degree of polymerization, and are numbers from 250 to 1100, and p<q. ]

PCT-A is a copolyester resin containing terephthalic acid and isophthalic acid as acid components and CHDM as a glycol component, and is represented by the following formula (6).

［（６）式中、ｐ、ｑは重合度であり、２５０～１１００の数である。］

[In formula (6), p and q are degrees of polymerization, and are numbers from 250 to 1100. ]

The non-foamed layer 20 may have a single layer structure or a multilayer structure of two or more layers.
When the non-foamed layer 20 has a multilayer structure, an outer layer of the above material (for example, polyamide), an inner layer of polyester resin (for example, crystalline polyethylene terephthalate (A-PET)), and an adhesive that bonds the outer layer and the inner layer. A multilayer film having an agent layer is preferred. In this multilayer film, the outer layer is located on the surface (exposed surface), and the inner layer is located on the foam layer 10 side.

The thickness T2 of the non-foamed layer 20 is determined taking into consideration the use of the laminated foamed sheet 1, and is preferably, for example, 10 to 300 μm, more preferably 20 to 200 μm. If the thickness T2 of the non-foamed layer 20 is greater than or equal to the above lower limit, the strength of the laminated foamed sheet 1 can be further improved. If the thickness T2 of the non-foamed layer 20 is equal to or less than the above upper limit, the weight of the laminated foamed sheet 1 can be reduced.
Thickness T2 is obtained by subtracting thickness T1 from thickness T.

<Method for manufacturing thermoplastic polyester resin laminated foam sheet>
The laminated foam sheet 1 is manufactured by a conventionally known manufacturing method.
The method for manufacturing the laminated foam sheet 1 involves obtaining a foam sheet with a single foam layer, and forming a non-foam layer 20 on at least one surface of the foam sheet.

The method for producing a foamed sheet includes the steps of melting a polyester resin, kneading the melted polyester resin and a foaming agent to obtain a kneaded product, extruding the kneaded product, and foaming it to obtain a foam layer.
As a suitable method for manufacturing such a foam sheet, a known method for manufacturing a foam sheet can be adopted, and examples thereof include the manufacturing method shown below.

A raw material composition containing a polyester resin and other components and a foaming agent are supplied to an extruder, melted, and kneaded to form a mixture. The temperature at which the polyester resin is melted (melting temperature: set temperature) is, for example, preferably 220 to 300°C, more preferably 240 to 290°C.
When the melting temperature is equal to or higher than the above lower limit, the polyester resin and other raw materials can be mixed uniformly. If the melting temperature is below the above upper limit, decomposition of the polyester resin can be suppressed.
The temperature (achieved temperature) of the mixture is preferably 280 to 330°C, more preferably 290 to 320°C. If the temperature reached is equal to or higher than the above lower limit, it will flow easily and can be extruded more smoothly from the extruder. If the reached temperature is below the above upper limit, decomposition of the polyester resin can be suppressed.

Subsequently, while the mixture is kneaded by a screw in the extruder, the mixture is extruded from a circular die attached to the tip of the extruder and foamed to obtain a cylindrical foam.
This cylindrical foam is expanded in diameter, supplied to a mandrel, and cooled. The cooled cylindrical foam is continuously cut in the extrusion direction and expanded to form a foam sheet.

Conventionally known methods can be used to provide the non-foamed layer 20 on one side of the foamed sheet.
For example, when forming a non-foamed layer with a multilayer structure (outer layer of polyamide/adhesive layer/inner layer of polyester resin), the following manufacturing method can be exemplified. A non-foamed sheet with a multilayer structure is prepared by dry laminating a pre-manufactured non-foamed sheet of polyamide and a pre-manufactured non-foamed sheet of polyester resin via an adhesive. Next, the surface of the inner layer (polyester resin) is thermally welded or thermocompressed to the polyester resin foam sheet.
Other methods include a method of thermally welding or thermocompression bonding a non-foamed sheet to a foamed sheet, a method of bonding a non-foamed sheet to a foamed sheet with an adhesive, and the like.
Adhesives are not particularly limited, and include ethylene copolymer adhesives made of copolymers with monomers such as methacrylic acid, cellulose adhesives, polyester adhesives, polyamide adhesives, polyimide adhesives, and urea. Amino resin adhesives made of resin or melamine resin, phenolic resin adhesives, epoxy adhesives, polyurethane adhesives, reactive (meth)acrylic adhesives, chloroprene rubber, nitrile rubber, styrene-butadiene rubber, etc. Examples include rubber adhesives made of, silicone adhesives, alkali metal silicates, inorganic adhesives made of low melting point glass, etc.

In addition, in the above-mentioned embodiment, the non-foamed layer is provided only on one side of the foamed layer. However, the present invention is not limited thereto, and a non-foamed layer may be provided on the other side of the foamed layer. That is, in the laminated foam sheet of the present invention, non-foamed layers may be provided on both sides of the foamed layer.
In addition, in the laminated foam sheet of the present invention, a printed layer may be provided on the surface of the non-foamed layer, and a non-foamed layer may be further provided on the surface of the printed layer.

(Thermoplastic polyester resin laminated foam container)
The thermoplastic polyester resin laminated foam container (foamed container) of the present invention is formed by molding the laminated foam sheet of the present invention described above.
The foam container has a bottom wall and a side wall rising from the periphery of the bottom wall. The foam container has an opening surrounded by an upper end of the side wall. The side wall portion may become narrower toward the bottom wall portion.
The shape of the foaming container is not particularly limited, and examples include trays with a plan view of a perfect circle, ellipse, semicircle, polygon, fan shape, etc., a bowl-shaped container, a cylindrical shape with a bottom, a rectangular cylindrical shape with a bottom, etc. Examples include various foam containers such as containers with lids such as containers for natto.
These foam containers are preferably used for foods, and more preferably for refrigerated foods or frozen foods.

The size of the foaming container is not particularly limited, and is appropriately determined in consideration of the intended use.
Foam containers for cooked foods include containers with a bottom wall measuring 10 to 30 cm in the longitudinal direction, 10 to 20 cm in the transverse direction of the bottom wall, and 3 to 10 cm in height.

The thickness of the bottom wall of the foaming container is, for example, preferably 0.2 to 3 mm, more preferably 0.5 to 2 mm. The thickness of the bottom wall portion is the average value of values measured at 10 random points using a thickness gauge.
The thickness of the side wall of the foaming container is, for example, preferably 0.2 to 3 mm, more preferably 0.5 to 2 mm. The thickness of the side wall portion is the average value of values measured at 10 random points using a thickness gauge.

<Physical properties>
The low temperature side DSC peak of the foam container is 170°C or higher, preferably 190°C or higher, and more preferably 200°C or higher, similar to the low temperature side DSC peak of the laminated foam sheet. If the low-temperature side DSC peak is equal to or higher than the above lower limit, cold resistance can be further improved. The upper limit of the low temperature side DSC peak is substantially 290°C.

Like the laminated foam sheet, the foam container preferably has two or more DSC peaks. By having two or more DSC peaks (that is, having at least one DSC peak on the high temperature side rather than the low temperature side DSC peak), heat resistance can be further improved.
When the foaming container has two or more DSC peaks, the other DSC peaks other than the low-temperature side DSC peak are preferably 190°C or higher, more preferably 200°C or higher, and even more preferably 220°C or higher.
The difference between the low-temperature side DSC peak and other DSC peaks is preferably 10 to 80°C, more preferably 20 to 70°C, and even more preferably 25 to 60°C.

The -20°C total absorbed energy of the foam container is 0.15 J or more, preferably 0.20 J or more, similar to the laminated foam sheet. If the total absorbed energy at -20°C is greater than or equal to the above lower limit, cold resistance can be further enhanced. The upper limit of the -20°C total absorbed energy is substantially 5.0 J or less.
Note that the -20°C total absorbed energy of the foaming container is the average value of the -20°C total absorbed energy of both sides of the bottom wall of the foaming container.

The Dynatap impact test is performed on a laminated foam sheet in the same manner, except that a circular sample with a diameter of 10 cm is cut out from the bottom wall of the container.

The dimensional change rate of the foamed container at 200° C. is less than 10%, more preferably less than 7%, and even more preferably less than 5%. If the dimensional change rate at 200°C is less than the above upper limit, heat resistance can be further improved.

A method for measuring the dimensional change rate of a foam container at 200°C will be explained.
A 50 mm square section is cut out from the bottom wall of the foam container and used as a sample. For example, if the bottom wall of the foam container has a long side on one side and a short side on the other side in plan view, it is cut out as a square with a length of 50 mm and a width of 50 mm. That is, the cut sample has a side along the longitudinal direction of the bottom wall and a side along the lateral direction of the bottom wall.
The cut sample is heated in a heating furnace at 200° C. for 10 minutes. Regarding the heated sample, a length L d1 in a direction along an arbitrary side (for example, a side along the longitudinal direction _{of the bottom wall part) on one surface, and a length L d2 in} a direction perpendicular to the arbitrary side, On the other surface, a length L _d11 in a direction along the arbitrary side and a length L _d12 in a direction perpendicular to the arbitrary side are measured. Let the average value of [length L _d1 ] and [length L _d11 ] be the average value of the length in the direction along the arbitrary side. Let the average value of [length L _d2 ] and [length L _d12 ] be the average value of the length in the direction orthogonal to the arbitrary side. The amount of dimensional change is calculated using the following formula (s2).
Amount of dimensional change (mm) = [Dimension of one side before heating: 50 mm] - [Average value of the length in the direction along the arbitrary side or in the direction perpendicular to the arbitrary side after heating] ... (s2 )
Among the absolute values of the calculated dimensional change amounts, the larger numerical value is defined as the "dimensional change value after heating (α2) mm." Let the value calculated by the following formula (s3) be the dimensional change rate (%).

Dimensional change rate (%) = [Dimension change value after heating (α2) mm] ÷ [Dimension of one side before heating: 50 mm] × 100 ... (s3)
Note that the lengths of line segments passing through the center of the square of the cut sample are respectively [length L _d1 ], [length L _d11 ], [length L _d2 ], and [length L _d12 ], and the sample is warped. In this case, the lengths of the line segments along the curved surface are respectively set as [length L _d1 ], [length L _d11 ], [length L _d2 ], and [length L _d12 ].

The basis weight of the foam layer of the foam container is similar to the basis weight of the foam layer of the laminated foam sheet.
The thickness of the foam layer of the foam container is similar to the thickness of the foam layer of the laminated foam sheet.
The Mz of the foam layer of the foam container is the same as the Mz of the foam layer of the laminated foam sheet.

The crystallinity of the foam layer of the foam container is preferably 15 to 30%, more preferably 16 to 28%, even more preferably 17 to 25%. If the degree of crystallinity of the foam layer is equal to or higher than the above lower limit, further improvement in heat resistance can be achieved. If the crystallinity of the foam layer is below the above upper limit, cold resistance can be further improved.

The degree of crystallinity is determined by the following formula (a).

Crystallinity (%) = {(Absolute value of heat of fusion (J/g) - Absolute value of heat of crystallization (J/g)) ÷ Complete heat of crystallization (J/g)} x 100... (a )

In the formula (a), the heat of fusion and the heat of crystallization can be determined from a DSC curve measured according to JIS K7122 (2012) "Method for measuring heat of transition of plastics". The measurement conditions are as follows.

Fill the bottom of an aluminum measurement container with 5 to 10 mg of the measurement sample without leaving any gaps.
Next, the temperature was maintained at 30° C. for 2 minutes under a nitrogen gas flow rate of 20 mL/min, and a DSC curve was obtained when the temperature was raised from 30° C. to 290° C. at a rate of 10° C./min. Alumina is used as a reference material at this time.

The calculated degree of crystallinity is calculated by calculating the difference between the heat of fusion (J/g) calculated from the area of the heat fusion peak and the heat of crystallization (J/g) calculated from the area of the crystallization peak, based on the theory of perfect crystallization of the resin. This is the value obtained by dividing by the heat of fusion. The heat of fusion and the heat of crystallization can be calculated using analysis software attached to the device.
The complete crystallization heat amount represents the heat amount when 100% crystallization is achieved. In addition, the complete crystallization heat amount of PET is 140.1 J/g.
The degree of crystallinity of the foam layer of the foam container can be adjusted by a combination of the temperature of the mold during molding, the molding time, etc. in the foam container manufacturing method described below.

<Method for manufacturing thermoplastic polyester resin laminated foam container>
The method for manufacturing a foam container is a method in which a laminated foam sheet is obtained by the above-described method for manufacturing a foam sheet of the present invention, and the obtained laminated foam sheet is heated and formed into an arbitrary shape to form a container.
As a suitable method for manufacturing such a foam container, a known method for manufacturing a foam container can be adopted, and examples thereof include the manufacturing method shown below.

First, the laminated foam sheet is heated to an arbitrary temperature to soften the laminated foam sheet (preheating step). In the preheating step, for example, the laminated foam sheet is heated to 120 to 130°C.
Next, the softened laminated foam sheet is sandwiched between a plug mold and a cavity mold (molds) heated to an arbitrary temperature, and molded into a desired shape. Thereafter, the male and female molds are separated and the molded container is taken out. The temperature of the mold during molding is preferably, for example, 170 to 200°C. The time during which the laminated foam sheet is sandwiched between the molds is preferably, for example, 3 to 20 seconds.

As mentioned above, the laminated foam sheet of the present invention has a foamed layer and a non-foamed layer, has a low-temperature side DSC peak in a specific range, has a total absorbed energy at -20°C in a specific range, and has Since the dimensional change rate is within a specific range, cold resistance can be further improved.
Further, the foamed container of the present invention has a foamed layer and a non-foamed layer, has a low-temperature side DSC peak in a specific range, has a -20°C total absorbed energy in a specific range, and has a dimensional change at 200°C. Since the rate is within a specific range, cold resistance can be further improved.

(Raw materials used)
<Foam sheet>
- A-1: Foamed sheet having a thickness of 0.75 mm, a basis weight of 330 g/m ² , and a Z average molecular weight Mz=390,000. Obtained in Production Example 1 below.

<<Manufacturing Example 1>> Method for manufacturing foam sheet A-1.
100 parts by mass of PET (Mz = 190,000) with intrinsic viscosity (IV value) = 1.04, 1.5 parts by mass of fine talc (crystal nucleating agent, trade name "MS-P", manufactured by Nippon Talc Co., Ltd.) and anhydrous 0.15 parts by mass of pyromellitic acid (crosslinking agent, trade name "Daicel pyromellitic anhydride", manufactured by Daicel Corporation) was dehumidified and dried in advance at 100° C. for 4 hours. The raw materials after dehumidifying and drying are melt-kneaded in an extruder with a diameter of 90 mm, nitrogen gas (9 parts by mass of nitrogen per 100 parts by mass of the kneaded material) is injected, and after kneading, extrusion is performed through a circular die with a diameter of 135 mm, and a mandrel is used. While cooling, it was formed into a sheet and rolled up.

<Non-foamed sheet>
- B-1: Unstretched nylon 6, trade name "Diamilon C-Z", manufactured by Mitsubishi Chemical Corporation.
・B-2: Unstretched PBT, homo PBT, manufactured by OG Film Co., Ltd.
- B-3: Copolyester (poly(1,4-cyclohexylene dimethylene terephthalate) copolyester resin), trade name "Tritan", manufactured by Eastman Chemical Company.
・B-4: Unstretched EVOH, product name "EVAL EF-F Grade", manufactured by Kuraray Co., Ltd.
- B-5: Biaxially oriented nylon 6, trade name "Superneal MXD nylon system SP-R", manufactured by Mitsubishi Chemical Corporation.
・B-6: Unstretched A-PET, product name "Bell FLL", manufactured by Towa Kako Co., Ltd.
・B-7: Biaxially stretched PBT, trade name "Boblet", manufactured by Kojin Film Co., Ltd.
- B-8: Unstretched PCT-A, trade name "Easter Copolyester AN004", manufactured by Eastman Chemical Company.

(Examples 1-4, 9-10, Comparative Examples 4-6)
The outer layer film and the inner layer film (non-foamed sheet B-6) were glued together with an adhesive (thickness 2 μm) [TM-250HV, manufactured by Toyo Morton Co., Ltd.] so that the non-foamed layer combinations shown in Tables 1 and 2 were obtained. A non-foamed sheet with a multilayer structure was obtained by dry laminating the film.
The inner layer of the resulting multilayered non-foamed sheet was placed on the foamed sheet with the surface of the inner layer facing the foamed sheet A-1 to form a contact laminate. The laminate was thermocompression bonded at 190° C. and 0.5 MPa to obtain a laminated foam sheet with a non-foamed layer formed on one side.
The obtained laminated foam sheet was measured for DSC peak, -20°C total absorbed energy, and dimensional change rate at 200°C.
The obtained laminated foam sheet was heated at 160° C. for 30 seconds. Next, compressed air was supplied from the plug mold side to bring the laminated foam sheet into close contact with the cavity mold, the plug mold and the cavity mold were closed for 6 seconds, and vacuum pressure air forming was performed at 180°C to obtain a laminated foam container. . The obtained laminated foam container was a rectangular container with an opening diameter of 140 mm x 100 mm, an opening flange width of 10 mm, a bottom wall inner diameter of 110 mm x 80 mm, and a height of 20 mm. The obtained laminated foam container had a non-foam layer formed on the inner surface of the container.
Regarding the obtained laminated foam container, the DSC peak, -20°C total absorbed energy, dimensional change rate at 200°C, and crystallinity of the foam layer were measured. In addition, the laminated foam containers of each example were evaluated by conducting heat resistance tests and cold resistance tests.
The measurement results are shown in Tables 1 and 2.

(Examples 5-8, Comparative Examples 1-3)
According to Tables 1 and 2, laminated foam sheets of each example were obtained in the same manner as in Example 1, except that a single layer non-foam sheet was used as the non-foam layer. The obtained laminated foam sheet was measured for DSC peak, -20°C total absorbed energy, and dimensional change rate at 200°C.
Further, a laminated foam container was obtained in the same manner as in Example 1 using the laminated foam sheets of each example. Regarding the obtained laminated foam container, the DSC peak, -20°C total absorbed energy, dimensional change rate at 200°C, and crystallinity of the foam layer were measured. In addition, the laminated foam containers of each example were evaluated by conducting heat resistance tests and cold resistance tests.

(Evaluation method)
<Heat resistance test (deformation)>
The foam containers of each example were heated in an oven at 200° C. for 10 minutes. Before and after heating, measure the longitudinal length (external dimension) of the upper end surface of the foam container and the length (external dimension) of the upper end in the lateral direction, and calculate the average dimension using the following formulas (s11) to (s13). The rate of change (%) was determined.

Dimensional change rate in the longitudinal direction (%) = (|[Longitudinal length of the upper end surface before heating] - [Longitudinal length of the upper end surface after heating] |) ÷ [Longitudinal length of the upper end surface before heating Length in direction]×100...(s11)
Dimensional change rate in the width direction (%) = (|[Length in the width direction of the upper end surface before heating] - [Length in the width direction of the upper end surface after heating] |) ÷ [Top length before heating Length of end face in transverse direction]×100...(s12)
Average dimensional change rate (%) = ([Longitudinal dimensional change rate (%)] + [Short side direction dimensional change rate (%)]) ÷ 2 ... (s13)

≪Evaluation criteria≫
5 points: Average dimensional change rate is less than 10%.
0 points: Average dimensional change rate is 10% or more.

<Heat resistance test (appearance)>
The foam containers of each example were heated in an oven at 200° C. for 10 minutes. After heating, the surface of the non-foamed layer was visually observed and evaluated according to the following evaluation criteria.

≪Evaluation criteria≫
5 points: The glossiness is maintained and it is beautiful.
4 points: Slightly cloudy.
2 points: Minute melting (floating) can be observed in the non-foamed layer.
0 points: The non-foamed layer is melted.

≪Comprehensive heat resistance evaluation≫
The lower score of the evaluation score of the heat resistance test (deformation) and the evaluation score of the heat resistance test (appearance) was taken as the evaluation score of heat resistance.

<Cold resistance>
200 mL of water was put into the foam container of each example and stored at -20°C for 6 hours to obtain a frozen product in a container. Three frozen products in containers were stacked to form one unit, four units were placed side by side in a cardboard box, and the cardboard was sealed to obtain a cardboard product. The product packed in cardboard was stored in an environment of -20°C for 16 hours. Thereafter, the product in the cardboard box was dropped from a height of 80 cm onto a concrete surface, and the frozen product in the container inside the cardboard box was visually observed. The damage status of the foam container was evaluated according to the following evaluation criteria.

≪Evaluation criteria≫
5 points: The number of foamed containers without cracks or defects (number of surviving containers) was 10 to 12.
4 points: The number of foamed containers without cracks or defects (number of surviving containers) was 7 to 9.
2 points: The number of foamed containers without cracks or defects (number of surviving containers) was 4 to 6.
0 points: The number of foamed containers without cracks or defects (number of surviving containers) was 0 to 3.

<Comprehensive evaluation>
A case where the total of the heat resistance score and the cold resistance score was 4 points or more, and both the heat resistance evaluation and the cold resistance evaluation were not 0 points, was judged to be "passed".

FIG. 5 is a DSC chart of the laminated foam sheet of Example 1. As shown in FIG. 5, the laminated foam sheet of Example 1 has two DSC peaks. The laminated foam sheet of Example 1 has a low-temperature side DSC peak at 221.5Cel (°C) and another DSC peak at 249.8Cel (°C).
As shown in Tables 1 and 2, Examples 1 to 8 to which the present invention was applied had an overall evaluation of 4 points or more.
On the other hand, in Comparative Examples 1 to 3, in which the -20 total absorbed energy of the laminated foam sheets was 0.08 to 0.14, the evaluation of cold resistance was 0 points.
The laminated foam sheets of Comparative Examples 4 to 6, which had a dimensional change rate of 12 to 15% at 200° C., were significantly deformed during molding and could not be molded into the desired shape. Also. The foamed containers of Comparative Examples 4 to 6 had a heat resistance rating of 0 points.

1 Thermoplastic polyester resin laminated foam sheet 10 Foam layer 20 Non-foam layer

Claims (17)

It has a foamed layer of thermoplastic polyester resin and a non-foamed layer provided on at least one surface of the foamed layer,
Among the one or more absorbed energy peaks measured by a heat flux differential scanning calorimeter when the temperature is raised from 30° C. to 290° C., the lowest absorbed energy peak is 170° C. or higher,
The total absorbed energy in the Dynatap impact test at -20°C is 0.15 J or more,
The dimensional change rate at 200°C determined by the following measurement method is less than 10%,
having two or more of the absorption energy peaks ,
Thermoplastic polyester resin laminated foam sheet.
<Measurement method>
A thermoplastic polyester resin laminated foam sheet measuring 50 mm in the MD direction and 50 mm in the TD direction is heated in a heating furnace at 200°C for 10 minutes, and the length L _m1 in the MD direction and the length L _t1 in the TD direction of one surface and the other surface are determined. The length L _m2 in the MD direction and the length L _t2 in the TD direction are measured, and the average value of [Length L _m1 ] and [Length L _m2 ] is taken as the average value of the length in the MD direction, and [Length L _t1 ] and [Length L _t2 ] as the average value of the length in the TD direction, and among the absolute values of the amount of dimensional change calculated by the following formula (s0), the larger value is determined as "after heating". The dimensional change value (α1) mm" and the value calculated by the following formula (s1) are defined as the dimensional change rate (%).
Amount of dimensional change (mm) = [Dimension of one side before heating: 50 mm] - [Average value of length in MD direction or TD direction after heating] ... (s0)
Dimensional change rate (%) = [Dimension change value after heating (α1) mm] ÷ [Dimension of one side before heating: 50 mm] × 100 ... (s1) The thermoplastic polyester resin laminated foam sheet according to claim 1, wherein the non-foamed layer is a non-stretched film. The non-foaming layer is made of polyamide, polybutylene terephthalate (PBT), amorphous polyethylene terephthalate (PET-G), poly(1,4-cyclohexylene dimethylene terephthalate) copolyester resin, polycyclohexylene dimethylene terephthalate ( Thermoplastic polyester system according to claim 1 or 2, comprising at least one member selected from the group consisting of PCT-G), acid-modified polycyclohexylene dimethylene terephthalate (PCT-A), and ethylene vinyl alcohol resin (EVOH). Resin laminated foam sheet. The thermoplastic polyester resin laminated foam sheet according to any one of claims 1 to 3 , wherein the absorption energy peak on the low temperature side is 200°C or higher. The thermoplastic polyester resin laminated foam sheet according to any one of claims 1 to 4 , wherein the foam layer has a basis weight of 200 to 1000 g/m ² . The thermoplastic polyester resin laminated foam sheet according to any one of claims 1 to 5 , having a thickness of 0.2 to 3 mm. The thermoplastic polyester resin laminated foam sheet according to any one of claims 1 to 6 , wherein the foam layer has a Z-average molecular weight Mz of 100,000 to 500,000. In a thermoplastic polyester resin laminated foam container having a bottom wall portion and a side wall portion rising from the periphery of the bottom wall portion,
It has a foamed layer of thermoplastic polyester resin and a non-foamed layer provided on at least one surface of the foamed layer,
Among the one or more absorbed energy peaks measured by a heat flux differential scanning calorimeter when the temperature is raised from 30° C. to 290° C., the lowest absorbed energy peak is 170° C. or higher,
The total absorbed energy in the Dynatap impact test at -20°C is 0.15 J or more,
The dimensional change rate at 200°C determined by the following measurement method is less than 10%,
having two or more of the absorption energy peaks ,
Thermoplastic polyester resin laminated foam container.
<Measurement method>
Cut out a 50 mm square section from the bottom wall of the thermoplastic polyester resin laminated foam container, heat this section in a heating furnace at 200° C. for 10 minutes, and measure the length L _d1 along any side on one surface. Measure the length L _d2 in the direction perpendicular to the arbitrary side, the length L _d11 in the direction along the arbitrary side on the other surface, and the length L _d12 in the direction perpendicular to the arbitrary side, The average value of [Length L _d1 ] and [Length L _d11 ] is the average value of the length in the direction along the arbitrary side, and the average value of [Length L _d2 ] and [Length L _d12 ] is the average value of the length in the direction orthogonal to the above arbitrary side, and among the absolute values of the dimensional change amount calculated by the following formula (s2), the larger value is the ``dimensional change value after heating (α2)''mm", and the value calculated by the following formula (s3) is taken as the dimensional change rate (%).
Amount of dimensional change (mm) = [Dimension of one side before heating: 50 mm] - [Average value of the length in the direction along the arbitrary side or in the direction perpendicular to the arbitrary side after heating] ... (s2 )
Dimensional change rate (%) = [Dimension change value after heating (α2) mm] ÷ [Dimension of one side before heating: 50 mm] × 100 ... (s3) In a thermoplastic polyester resin laminated foam container having a bottom wall portion and a side wall portion rising from the periphery of the bottom wall portion,
It has a foamed layer of thermoplastic polyester resin and a non-foamed layer provided on at least one surface of the foamed layer,
Among the one or more absorbed energy peaks measured by a heat flux differential scanning calorimeter when the temperature is raised from 30° C. to 290° C., the lowest absorbed energy peak is 170° C. or higher,
The total absorbed energy in the Dynatap impact test at -20°C is 0.15 J or more,
The dimensional change rate at 200°C determined by the following measurement method is less than 10%,
The crystallinity of the foam layer is 15% or more and 30% or less ,
Thermoplastic polyester resin laminated foam container.
<Measurement method>
Cut out a 50 mm square section from the bottom wall of the thermoplastic polyester resin laminated foam container, heat this section in a heating furnace at 200° C. for 10 minutes, and measure the length L <sub>d1</sub> along any side on one surface. Measure the length L <sub>d2</sub> in the direction perpendicular to the arbitrary side, the length L <sub>d11</sub> in the direction along the arbitrary side on the other surface, and the length L <sub>d12</sub> in the direction perpendicular to the arbitrary side, The average value of [Length L <sub>d1</sub> ] and [Length L <sub>d11</sub> ] is the average value of the length in the direction along the arbitrary side, and the average value of [Length L <sub>d2</sub> ] and [Length L <sub>d12</sub> ] is the average value of the length in the direction perpendicular to the above arbitrary side, and among the absolute values of the dimensional change amount calculated by the following formula (s2), the larger value is the ``dimensional change value after heating (α2)''mm", and the value calculated by the following formula (s3) is taken as the dimensional change rate (%).
Amount of dimensional change (mm) = [Dimension of one side before heating: 50 mm] - [Average value of the length in the direction along the arbitrary side or in the direction perpendicular to the arbitrary side after heating] ... (s2 )
Dimensional change rate (%) = [Dimension change value after heating (α2) mm] ÷ [Dimension of one side before heating: 50 mm] × 100 ... (s3) The thermoplastic polyester resin laminated foam container according to claim 8 or 9 , wherein the non-foamed layer is a non-stretched film. The non-foaming layer is made of polyamide, polybutylene terephthalate (PBT), amorphous polyethylene terephthalate (PET-G), poly(1,4-cyclohexylene dimethylene terephthalate) copolyester resin, polycyclohexylene dimethylene terephthalate ( PCT-G), acid-modified polycyclohexylene dimethylene terephthalate (PCT-A), and ethylene vinyl alcohol resin ( EVOH ). Thermoplastic polyester resin laminated foam container. The thermoplastic polyester resin laminated foam container according to any one of claims 8 to 11, which has two or more absorption energy peaks, and the absorption energy peak on the low temperature side is 200° C. or higher. The thermoplastic polyester resin laminated foam container according to any one of claims 8 to 12 , wherein the foam layer has a basis weight of 200 to 1000 g/m ² . The thermoplastic polyester resin laminated foam container according to any one of claims 8 to 13 , wherein the bottom wall portion has a thickness of 0.2 to 3 mm, and the side wall portion has a thickness of 0.2 to 3 mm. . The thermoplastic polyester resin laminated foam container according to any one of claims 8 to 14 , wherein the foam layer has a Z-average molecular weight Mz of 100,000 to 500,000. The thermoplastic polyester resin laminated foam container according to any one of claims 8 to 15 , which is for food use. The thermoplastic polyester resin laminated foam container according to claim 16 , which is for refrigerated food or frozen food.

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