TW201833219A - Thermoplastic polyester resin foam sheet and thermoplastic polyester resin foam container - Google Patents

Abstract

A thermoplastic polyester resin foam sheet includes a thermoplastic polyester resin and a crystallization accelerator that is at least one selected from the group consisting of an inorganic crystallization accelerator and an organic crystallization accelerator. The thermoplastic polyester resin foam sheet is characterized in that in a DSC curve obtained when a second temperature increase is performed using a heat flux differential scanning calorimeter (DSC) so that the temperature of the thermoplastic polyester resin foam sheet increases from 30 to 110 DEG C at a heating speed of 100 DEG C/min. and the temperature thereof is kept at 110 DEG C for 30 minutes, a time (crystallization time) from the start time of the second temperature increase to a peak top A that is a heating peak and that is shown at the latest time is 14 minutes or less.

Description

   Thermoplastic polyester resin foamed sheet and thermoplastic polyester resin foamed container   

The invention relates to a thermoplastic polyester resin foamed sheet and a thermoplastic polyester resin foamed container.

This application claims priority based on Japanese Patent Application No. 2016-235780 filed in Japan on December 5, 2016 and Japanese Patent Application No. 2017-071103 filed in Japan on March 31, 2017, and the contents are incorporated herein by reference.

It is generally known that a container formed by molding a thermoplastic polyester-based resin foamed sheet (hereinafter also simply referred to as "foamed sheet") has excellent heat resistance. Therefore, such a container is widely used as a container for food processed in a microwave oven or an oven.

If a thermoplastic polyester resin foamed sheet is to be formed into a container, the foamed sheet is generally preheated to a moldable temperature, and then the preheated foamed sheet is molded using a mold having a predetermined shape.

At this time, when the preheating temperature is higher than the crystallization temperature of the thermoplastic polyester resin, the resin on the surface of the foamed sheet is crystallized before it is sufficiently preheated to the inside of the foamed sheet to make The elongation is poor and the container is liable to cause poor molding.

When the preheating temperature is lower than the crystallization temperature of the thermoplastic polyester resin, the crystallization of the thermoplastic polyester resin is insufficient, and the heat resistance of the obtained container is insufficient.

In response to such a problem, in Patent Document 1, pre-heating is performed at a temperature lower than the crystallization temperature of the thermoplastic polyester resin and the temperature required for forming the foamed sheet. A mold having a higher crystallization temperature is used to hold and shape the foamed sheet, thereby improving the heat resistance of the container.

    [Prior technical literature]         [Patent Literature]    

[Patent Document 1] Japanese Unexamined Patent Publication No. 3-239527

However, in the technique of Patent Document 1, in order to increase the degree of crystallization of the thermoplastic polyester resin, the time required to hold the foamed sheet in a mold is increased. Therefore, there is a problem that it takes time for the forming step and the productivity of the container cannot be improved.

Therefore, an object of the present invention is to provide a thermoplastic polyester-based resin foamed sheet, which can obtain a container having high heat resistance and improve the productivity of the container.

In order to solve the above problems, the present invention has the following aspects.

[1] A thermoplastic polyester-based resin foamed sheet comprising a thermoplastic polyester-based resin and one or more crystallization accelerators selected from the group consisting of inorganic-based crystallization accelerators and organic-based crystallization accelerators; The crystallization time measured by the thermoplastic polyester resin foamed sheet using the following measurement method is 14 minutes or less. <Measurement method> A measurement sample is taken from the thermoplastic polyester resin foamed sheet, and the heat flux difference is used. Scanning calorimetry (DSC) device, heating the measurement sample at a heating rate of 100 ° C / min from 30 ° C to 290 ° C for the first time, and maintaining the temperature at 290 ° C for 10 minutes. Take out the inside, leave it at 23 ° C for 10 minutes, and then return it to the measuring device at 30 ° C. The second heating is performed from 30 ° C to 110 ° C at a heating rate of 100 ° C / min, and it is held at 110 ° C for 30 minutes ; In the DSC curve obtained at the second temperature increase, the time from "the time when the second temperature increase is started" to "the time when the peak of the heat generation peak displayed at the latest time" is used as the crystallization time.

[2] The thermoplastic polyester-based resin foamed sheet according to [1], wherein the crystallization promoter is granular, and the crystallization promoter of the thermoplastic polyester-based resin foamed sheet is The major axis of the particle diameter is 50 μm or less.

[3] The thermoplastic polyester-based resin foamed sheet according to [1], wherein the crystallization accelerator is granular, and the average primary particle diameter is 0.05 μm or more and 50 μm or less.

[4] The thermoplastic polyester-based resin foamed sheet according to [1], wherein the crystallization accelerator contains at least one selected from the group consisting of talc, carbon black, and a metal oxide.

[5] The thermoplastic polyester-based resin foamed sheet according to [1], wherein the metal oxide is zinc oxide.

[6] The thermoplastic polyester-based resin foamed sheet according to [1], wherein the content of the crystallization accelerator is from 0.05 parts by mass to 5 parts by mass based on 100 parts by mass of the thermoplastic polyester-based resin. Below

[7] The thermoplastic polyester resin foamed sheet according to [1], in which the existence ratio of molecules having a molecular weight of 10,000 or less expressed by a differential molecular weight distribution in the thermoplastic polyester resin is relative The total mass of the thermoplastic polyester resin is 6.0% by mass or less.

[8] The thermoplastic polyester resin foamed sheet according to [1], wherein the thermoplastic polyester resin is a polyethylene terephthalate resin.

[9] The thermoplastic polyester resin foamed sheet according to [1], which is used for food packaging containers.

[10] A method for producing a thermoplastic polyester-based resin foamed sheet according to [1], comprising the steps of: supplying a mixture containing a thermoplastic polyester-based resin, a crystallization accelerator, and a foaming agent to an extruder; A step of preparing a machine to perform a melt-kneading to obtain a resin composition; and a step of foaming and curing the resin composition.

[11] A thermoplastic polyester resin foaming container containing a thermoplastic polyester resin and one or more crystallization accelerators selected from the group consisting of inorganic crystallization accelerators and organic crystallization accelerators; The crystallization time measured by the thermoplastic polyester resin foamed container using the following measurement method is 14 minutes or less; <measurement method> A measurement sample is taken from the thermoplastic polyester resin foamed container, and a heat flux differential is used for the measurement. Scanning calorimetry (DSC) device, heating the measurement sample at a heating rate of 100 ° C / min from 30 ° C to 290 ° C for the first time, and holding it at 290 ° C for 10 minutes; secondly, removing the measurement sample from the measurement device Take out the inside, leave it at 23 ° C for 10 minutes, and then return it to the measuring device at 30 ° C. The second heating is performed from 30 ° C to 110 ° C at a heating rate of 100 ° C / min, and it is held at 110 ° C for 30 minutes. ; In the DSC curve obtained at the second temperature increase, the time from "the time when the second temperature increase is started" to "the time when the peak of the heat generation peak displayed at the latest time" is used as the crystallization time.

[12] The thermoplastic polyester resin foaming container according to [11], wherein the crystallization accelerator is granular, and the crystallization accelerator in the thermoplastic polyester resin foaming container is The major axis of the particle diameter is 50 μm or less.

[13] The thermoplastic polyester-based resin foaming container according to [11], wherein the crystallization accelerator is granular, and the average primary particle diameter is 0.05 μm or more and 50 μm or less.

[14] The thermoplastic polyester-based resin foaming container according to [11], wherein the crystallization accelerator contains at least one selected from the group consisting of talc, carbon black, and a metal oxide.

[15] The thermoplastic polyester resin foamed container according to [14], wherein the metal oxide is zinc oxide.

[16] The thermoplastic polyester-based resin foaming container according to [11], wherein the content of the crystallization accelerator is 0.05 parts by mass or more and 5 parts by mass based on 100 parts by mass of the thermoplastic polyester-based resin. The following.

[17] The thermoplastic polyester resin foaming container according to [11], wherein the existence ratio of molecules having a molecular weight of 10000 or less expressed by a differential molecular weight distribution in the thermoplastic polyester resin is relative to The total mass of the thermoplastic polyester resin is 6.0% by mass or less.

[18] The thermoplastic polyester resin foaming container according to [11], wherein the thermoplastic polyester resin is a polyethylene terephthalate resin.

[19] The thermoplastic polyester resin foaming container according to [11], which is a food packaging container.

[20] The thermoplastic polyester resin foaming container according to [11], which is a refrigerated microwave heating container.

[21] A method for producing a thermoplastic polyester-based resin foaming container according to [11], comprising the steps of: applying a resin composition containing a thermoplastic polyester-based resin, a crystallization accelerator, and a foaming agent; The foaming and hardening thermoplastic polyester resin foamed sheet is subjected to a preheating preheating step; a mold is used to sandwich the preheated thermoplastic polyester resin foamed sheet and heat-mold the molding step; A cooling step of cooling the molded thermoplastic polyester resin foamed sheet; and a step of cutting the molded body from the cooled thermoplastic polyester resin foamed sheet.

By using the thermoplastic polyester-based resin foamed sheet of the present invention, a container having high heat resistance can be obtained and the productivity of the container can be improved.

A‧‧‧ The peak of the fever spike displayed at the latest time

FIG. 1 is an example of a DSC curve when time (minutes) is plotted on the horizontal axis and thermal DSC (mW) is plotted on the vertical axis.

(Thermoplastic polyester resin foam sheet)

The thermoplastic polyester-based resin foamed sheet of the present invention (hereinafter also referred to simply as "foamed sheet") includes a thermoplastic polyester-based resin (hereinafter also referred to as "polyester-based resin") and crystallization promotion Agent foaming resin layer. The foamed resin layer is formed of a resin composition containing a polyester resin, a crystallization accelerator, and a foaming agent.

The foamed sheet may have a single-layer structure composed of only a foamed resin layer, or a laminated structure in which a non-foamed resin layer or the like is provided on at least one side of the foamed resin layer. The non-foaming resin layer is preferably a resin containing the polyester, polyolefin, and polystyrene described above. By making a laminated structure, it is possible to further enhance the strength and obtain the aesthetics.

The thickness of the foamed sheet is preferably 0.3 to 5.0 mm, more preferably 0.4 to 4.5 mm, and even more preferably 0.5 to 4.0 mm. When it is more than the said lower limit value, the intensity | strength of the thermoplastic-polyester-type resin foam container (henceforth a "foam container") mentioned later can be improved further. When it is below the above-mentioned upper limit value, it is easy to sufficiently heat the inside of the foamed sheet.

The basis weight of the foamed sheet is preferably 250 to 900 g / m ^{2, more} preferably 250 to 800 g / m ² , and even more preferably 300 to 700 g / m ² . When it is at least the above lower limit value, the strength of the foamed container can be further increased. When it is at most the above upper limit value, it is easier to form a foamed container.

The expansion ratio of the foamed sheet is preferably 1.5 to 15 times, more preferably 2 to 10 times, and even more preferably 3 to 8 times. When it is at least the above lower limit value, the thermal insulation property of the foamed container can be further improved. When it is below the above-mentioned upper limit value, it is easy to sufficiently heat the inside of the foamed sheet.

<Polyester resin>

Examples of the polyester resin include polyethylene terephthalate resin, polybutylene terephthalate resin, polyethylene naphthalate resin, and polyethylene furanoate. ) Resins, polybutylene naphthalate resins, copolymers of terephthalic acid, ethylene glycol and cyclohexanedimethanol, and mixtures thereof, and mixtures of these with other resins. In addition, plant-derived polyethylene terephthalate resin and polyethylene furandicarboxylate resin can also be used. These polyester resins may be used singly or in combination of two or more kinds. A particularly preferred polyester resin is polyethylene terephthalate resin.

For polyester resins, when mixed with other resins, the content of other resins is preferably less than 50% by mass, and more than 0% by mass and 30% by mass or less relative to the total mass of the polyester resin. Preferably, it is more than 0% by mass and 20% by mass or less.

The mass average molecular weight of the polyester resin is preferably 100,000 to 500,000, more preferably 150,000 to 450,000, and even more preferably 200,000 to 400,000. When the mass average molecular weight of the polyester-based resin is within the above range, a foamed sheet having good brittleness is easily obtained. The mass average molecular weight is a value measured by gel permeation chromatography (GPC) based on the use of the product names "STANDARD SM-105" and "STANDARD SH-75" manufactured by Showa Denko Corporation as standard samples The value obtained by converting the calibration curve of.

In the foamed sheet, the existence ratio of molecules with a molecular weight of 10000 or less expressed by a differential molecular weight distribution in the polyester resin is preferably 6.0% by mass or less with respect to the total mass of the polyester resin, and 5.5 mass % Or less is preferred, and 5.0% by mass or less is more preferred. In addition, it is preferably greater than 0% by mass and 6.0% by mass or less, more preferably greater than 0% by mass and 5.5% by mass or less, and more preferably greater than 0% by mass and 5.0% by mass or less. When the said presence ratio is below the said upper limit, it is easy to obtain the foamed container excellent in both heat resistance and cold brittleness resistance.

The lower limit value is not particularly limited as long as it is greater than 0% by mass, and is substantially 1.0% by mass or more.

The limiting viscosity (IV value) of the polyester resin is preferably 0.50 to 1.50, and more preferably 0.90 to 1.10. When the IV value is equal to or more than the above lower limit value, foaming is easy and an extruded foamed sheet is easily obtained. When the IV value is equal to or less than the above upper limit value, a smooth sheet is easily obtained.

The IV value can be measured in accordance with the method of JIS K7367-5 (2000).

<Crystallization promoter>

The crystallization accelerator of the present invention is one or more selected from the group consisting of an inorganic crystallization accelerator and an organic crystallization accelerator.

Examples of the inorganic crystallization accelerator include silicate, carbon, and metal oxides. Examples of the silicate include talc, which is a hydrous magnesium silicate. Examples of carbon include carbon black, nano carbon fiber, nano carbon tube, carbon nanohorn, activated carbon, graphite, graphene, coke, mesoporous carbon, Glassy carbon, hard carbon, soft carbon, and the like; examples of carbon black include furnace black, acetylene black, Ketjen black, and thermal black. Examples of the metal oxide include zinc oxide and titanium oxide.

Examples of the organic crystallization promoter include aliphatic carboxylic acids, and examples thereof include stearic acid, montanic acid, and salts thereof.

When the crystallization accelerator is granular, the crystallization accelerator preferably contains one or more selected from the group consisting of talc, carbon black, and a metal oxide.

By containing one or more kinds selected from talc, carbon black, and metal oxides as a crystallization accelerator, it is easy to obtain a foamed sheet excellent in both heat resistance and cold brittleness resistance.

These crystallization accelerators are preferably talc, carbon black, and zinc oxide. When such a crystallization accelerator is used, a container having high heat resistance can be obtained, and the productivity of the container can be more easily improved.

These crystallization accelerators may be used individually by 1 type, and may be used in combination of 2 or more type.

The average primary particle diameter of the granular crystallization accelerator such as talc or carbon black added to the polyester resin is preferably from 0.05 to 50 μm, more preferably from 0.05 to 30 μm, and even more preferably from 0.1 to 25 μm. When the average primary particle diameter of the crystallization accelerator is greater than or equal to the above-mentioned lower limit value, the crystallization accelerator easily exhibits the effect of promoting crystallization. When the average primary particle diameter of the crystallization accelerator is equal to or less than the above upper limit value, the crystallization accelerator is easily dispersed in the foamed sheet.

The average primary particle diameter can be measured using a laser diffraction method.

These crystallization accelerators also exist in the form of agglomerates due to the aggregation of a plurality of primary particles in the foamed sheet. The particle diameter of the crystallization accelerator in the foamed sheet of the present specification is defined as follows. That is, when the crystallization accelerator in the foamed sheet exists in the form of primary particles, it is the major diameter of the primary particles. When the crystallization accelerator in the foamed sheet exists in the form of agglomerates, it is the major diameter of the agglomerates. When both primary particles and aggregates are contained in the foamed sheet, the longest diameter of the largest primary particles or aggregates is obtained.

The particle diameter of the crystallization accelerator in the foamed sheet is preferably 50 μm or less, more preferably 40 μm or less, and even more preferably 25 μm or less. When the long diameter of the particle diameter of the crystallization accelerator is equal to or less than the above-mentioned upper limit value, the degree of crystallization of the thermoplastic polyester resin is easily improved, and a foamed container having more excellent heat resistance is easily obtained.

The lower limit value is not particularly limited as long as it is larger than 0 μm, and is substantially 0.05 μm or more.

The particle diameter of the crystallization accelerator in the foamed sheet can be measured using a scanning electron microscope (SEM) or a transmission electron microscope (TEM). The particle diameter is known as the arithmetic mean particle diameter from the description of the measurement method described later.

The content of the crystallization accelerator is preferably 0.1 to 5% by mass, and more preferably 0.5 to 3% by mass relative to the total mass of the foamed sheet. When the content of the crystallization accelerator is greater than or equal to the above lower limit value, a foamed container having more excellent heat resistance is easily obtained. When the content is less than or equal to the above upper limit value, it is easy to reduce variations in density and thickness of the foamed sheet.

<Foaming agent>

Examples of the blowing agent include saturated aliphatic hydrocarbons such as propane, n-butane, isobutane, n-pentane, isopentane, and hexane; ethers such as dimethyl ether; and methyl chloride. , 1,1,1,2-tetrafluoroethane, 1,1-difluoroethane, chlorodifluoromethane and other halogenated hydrocarbon compounds, carbon dioxide, nitrogen, etc., with dimethyl ether, propane, n-butane, isopropyl Butane, carbon dioxide and nitrogen are preferred. These foaming agents may be used individually by 1 type, and may be used in combination of 2 or more type.

The content of the foaming agent is preferably 0 to 4 parts by mass, and more preferably 0 to 3 parts by mass with respect to 100 parts by mass of the polyester-based resin.

<Optional component>

The foamed sheet of the present invention may contain other components (optional components) in addition to the polyester resin, the crystallization accelerator, and the foaming agent.

Examples of the optional component include a cross-linking agent, a bubble regulator, a surfactant, a colorant, an anti-shrinking agent, a flame retardant, a lubricant, and an anti-deterioration agent.

Examples of the crosslinking agent include acid dianhydrides such as pyromelite dianhydride, polyfunctional epoxy compounds, Oxazoline compounds, Oxazine compounds and the like.

The content is preferably 0.01 to 10 parts by mass, and more preferably 0.05 to 5 parts by mass, relative to 100 parts by mass of the polyester-based resin.

The foaming sheet of the present invention has a crystallization time at 110 ° C of 14 minutes or less, preferably 12 minutes or less, and more preferably 10 minutes or less.

By setting the crystallization time at 110 ° C to 14 minutes, the degree of crystallization of the polyester resin can be improved and a foamed container having excellent heat resistance can be obtained. In addition, by setting the crystallization time at 110 ° C to 14 minutes or less, the time required for the forming step can be shortened and the productivity of the foamed container can be improved.

The lower limit value is not particularly limited as long as the polyester-based resin can be crystallized, and is substantially 4 minutes or more.

The crystallization time can be adjusted by the type or amount of the polyester-based resin and the type or amount of the crystallization accelerator.

In addition, the crystallization time in the present invention refers to a time measured using the following crystallization time measurement method.

(Measurement method of crystallization time)

A measurement sample was taken from the thermoplastic polyester-based resin foamed sheet, and the measurement sample was subjected to the first measurement at a heating rate of 100 ° C / min from 30 ° C to 290 ° C using a thermal beam differential scanning calorimetry (DSC) device. The temperature was raised twice and held at 290 ° C for 10 minutes.

Next, the measurement sample was taken out of the measurement device, and left at 23 ° C for 10 minutes, and then returned to the measurement device at 30 ° C. The second heating was performed at a heating rate of 100 ° C / min from 30 ° C to 110 ° C, and the temperature was maintained at 110 ° C for 30 minutes.

In the DSC curve obtained when the second heating was performed, the time from "the time after the second heating was started" to "the time when the peak of the heat generation peak was displayed at the latest time" was taken as the crystallization time.

(Manufacturing method of foamed sheet)

The thermoplastic polyester resin foamed sheet can be produced by foaming and curing a resin composition containing a polyester resin, a crystallization accelerator, and a foaming agent.

As a preferable manufacturing method of this foamed sheet, the conventional manufacturing method of a foamed sheet can be used, For example, the manufacturing method disclosed below is mentioned.

The polyester resin, crystallization accelerator, foaming agent, and optional components are supplied to an extruder and melt-kneaded to prepare a molten mixture of the resin composition.

Generally, polyester resins are resins that are easily hydrolyzed at high temperatures. Therefore, it is preferable to dry the polyester resin in advance. As the drying system, for example, a dehumidifying dryer can be used. The drying method is sufficient as long as the air having a dew point of -30 ° C is heated to 160 ° C and the polyester resin is exposed to the air.

The content of the crystallization accelerator is preferably 0.05 parts by mass or more and 5 parts by mass or less based on 100 parts by mass of the polyester-based resin, preferably 0.1 parts by mass or more and 4 parts by mass or less, and 0.5 parts by mass or more and 3 parts by mass Servings below are better. By making it more than the said lower limit value, it becomes easy to promote crystallization of a polyester resin. By making it below the said upper limit, the cold brittleness resistance of a foaming container can be improved further.

When the resin composition contains a crosslinking agent, the content of the crosslinking agent is preferably 0.01 to 5 parts by mass, more preferably 0.02 to 4 parts by mass, and 0.05 to 3 parts by mass relative to 100 parts by mass of the polyester-based resin. Serve is better. By making it more than the said lower limit, the cold brittleness of a foaming container can be improved more. By making it below the said upper limit, the viscosity increase of a molten mixture can be suppressed.

Next, the molten mixture was extruded and foamed from a circular mold mounted on the front end of the extruder to obtain a cylindrical foam. After expanding the diameter of this cylindrical foam, it was supplied to a mandrel and cooled. A method of producing a foamed sheet by continuously cutting and expanding a cooled cylindrical foam in the extrusion direction between its inner and outer peripheral surfaces can be mentioned.

Examples of the method for quantifying the crystallization accelerator in the foamed sheet include ash measurement, differential thermal / thermogravimetric simultaneous measurement (TG / DTA), and fluorescent X-ray measurement.

When the crystallization accelerator is talc, the amount of talc in the ash can be determined and the amount of talc can be determined (measurement of ash).

In the case of crystallization accelerator carbon black, the amount of carbon black can be determined by analyzing a foamed sheet cut to an arbitrary size using a TG / DTA device.

When the crystallization accelerator is zinc oxide, the mass of zinc metal can be measured and converted using fluorescent X-rays to obtain the mass of zinc oxide.

When the crystallization accelerator is an organic crystallization accelerator, the crystallization accelerator may be decomposed and dispersed in the foamed sheet, or the crystallization accelerator may react with a polyethylene terephthalate resin, so it cannot be used. Quantify the content of crystallization accelerator.

When two or more crystallization accelerators are used in combination, the content of each crystallization accelerator can be quantified by using the above-mentioned quantitative method in combination.

In the present specification, the content of the crystallization accelerator in the foamed sheet is expressed in terms of parts by mass of the crystallization accelerator with respect to 100 parts by mass of the polyester-based resin.

When talc is used as the crystallization accelerator, the obtained foamed flakes are white, and when carbon black is used as the crystallization promoter, the obtained foamed flakes are gray to black. When an organic crystallization accelerator and zinc oxide are used as the crystallization accelerator, the obtained foamed flakes become white.

(Thermoplastic polyester resin foam container)

The thermoplastic polyester-based resin foamed container of the present invention (hereinafter also simply referred to as "foamed container") is formed by molding the above-mentioned thermoplastic polyester-based resin foamed sheet into a desired shape using a known molding method or the like. Successor.

(Degree of crystallization)

Regarding the foaming container of the present invention, the degree of crystallinity calculated by the following formula (1) is preferably 21% to 30%, and more preferably 21% to 27%.

Degree of crystallization (%) = {(absolute value of heat of fusion (J / g)-absolute value of heat of crystallization (J / g)) ÷ heat of complete crystallization (J / g)} × 100. ． ． (1)

By setting the degree of crystallization to the above range, the heat resistance of the foamed container can be easily improved.

Here, the heat of fusion and the heat of crystallization can be obtained from a DSC curve measured in accordance with JIS K7122 (2012) "Method for Measuring Heat Transfer of Plastics". The measurement conditions are as follows.

The bottom of the aluminum measurement container was filled with 5 to 10 mg of the measurement sample so as not to generate a gap using DSC.

Next, a DSC curve was obtained when the temperature was maintained at 30 ° C. for 2 minutes under a nitrogen flow rate of 20 mL / minute, and the temperature was increased from 30 ° C. to 290 ° C. at a rate of 10 ° C./minute. Alumina was used as a reference substance at this time.

The degree of crystallization calculated in the present invention refers to the "heat of fusion (J / g) obtained from the area of the melting peak" and the "heat of crystallization (J / g) obtained from the area of the peak of melting" "And divide it by" theoretical melting heat of complete crystallization of the resin "to obtain the value obtained. The heat of fusion and the heat of crystallization can be calculated using analysis software attached to the device.

The heat of complete crystallization refers to the heat at 100% crystallization. In addition, the heat of complete crystallization of PET was 140.1 J / g.

The degree of crystallization of the resin foam container can be adjusted by the molding conditions of the foamed sheet.

The type and particle size of the crystallization accelerator contained in the foaming container are the same as the type and particle size of the crystallization accelerator in the foamed sheet.

The presence ratio of molecules having a molecular weight of 10000 or less expressed by the differential molecular weight distribution in the polyester resin of the foaming container is equal to or less than 10,000 of the molecular weight represented by the differential molecular weight distribution in the polyester resin of the foamed sheet. The presence ratio of the molecules is the same. The crystallization time of the polyester-based resin in the foamed container is the same as the crystallization time of the polyester-based resin in the foamed sheet.

(Manufacturing method of foam container)

Examples of the method for producing the foamed container of the present invention include conventionally known methods.

For example, a foamed container can be manufactured by a manufacturing method including the following steps: a preheating step of preheating the foamed sheet; and after the aforementioned preheating step, the foamed sheet is sandwiched by a mold and then heat-formed The forming step. Furthermore, the method may further include a cooling step of cooling the molded foamed sheet after the molding step.

<Preheating step>

The preheating step is a step of putting the foamed sheet into a heater tank and preheating to soften the foamed sheet. The temperature of the heater tank is preferably 90 to 180 ° C, more preferably 100 to 170 ° C, and even more preferably 105 to 160 ° C. By making it into the said lower limit value or more, a foamed sheet can be shape | molded more easily. By making it into the said upper limit or less, crystallization of a polyester resin can be suppressed.

At this time, the surface temperature of the foamed sheet is preferably 105 to 140 ° C, more preferably 110 to 135 ° C, and even more preferably 115 to 130 ° C. By making it into the said lower limit or more, a foamed sheet can be shape | molded more easily. By making it into the said upper limit or less, crystallization of the polyester resin on the surface of a foamed sheet can be suppressed.

The preheating time of the foamed sheet in the preheating step is preferably 20 to 90 seconds, more preferably 20 to 85 seconds, and even more preferably 30 to 80 seconds. By making it into the said lower limit value or more, a foamed sheet can be shape | molded more easily. By making it into the said upper limit or less, crystallization of the polyester resin on the surface of a foamed sheet can be suppressed.

<Forming step>

The molding step is a step of sandwiching the pre-heated foamed sheet with a mold, heating it further, and molding the foamed container into a desired shape.

Examples of the forming method include vacuum forming and pressure forming, and particularly, pressure forming is preferred. Examples of vacuum forming and pressure forming include plug forming, free drawing forming, plug and ridge forming, matched mold forming, and straight forming. , Covering forming (drape forming), reverse draw (reverse draw) forming, air slip forming (plugging), plug assist forming (reverse draw), etc.

In the forming step, the mold temperature is preferably 130 to 200 ° C, more preferably 140 to 195 ° C, and even more preferably 160 to 190 ° C. By making it more than the said lower limit, the crystallinity of a polyester resin can be improved. By making it below the said upper limit, excessive crystallization of a polyester resin can be suppressed.

In the forming step, the time for heat forming is preferably 4 to 15 seconds, more preferably 5.0 to 13 seconds, and even more preferably 6.0 to 12 seconds. By making it more than the said lower limit, the crystallinity of a polyester resin can be improved. By setting it as below the said upper limit, productivity of a foaming container can be improved.

In the forming step, the absolute value of the heat of crystallization of the polyester-based resin is preferably 1 to 5 mJ / mg, more preferably 1.2 to 4.8 mJ / mg, and even more preferably 1.5 to 4.5 mJ / mg. By making it more than the said lower limit, the crystallinity of a polyester resin can be improved. By making it below the said upper limit, excessive crystallization of a polyester resin can be suppressed.

In the air-pressure molding, it is preferable that a male mold and a female mold heated to 160 to 200 ° C are used as molds, and compressed air is supplied from the male mold side to preheat the thermoplastic polyester resin foamed sheet. Close the male mold for 4 to 15 seconds.

The temperature of the mold in the forming step is preferably higher than the temperature of the heater tank in the preheating step.

<Cooling step>

The cooling step is a step of cooling the formed foamed sheet.

In the cooling step, the formed foamed sheet is cooled to a surface temperature of 50 to 70 ° C.

In the cooling step, the formed foamed sheet is preferably cooled in 50 to 60 seconds until the surface temperature of the foamed sheet becomes 50 to 70 ° C. By cooling, the polyester resin can be crystallized and the degree of crystallization can be 21% or more.

After cooling, the molded body was cut out from the foamed sheet and used as a foaming container.

The content of the crystallization accelerator in the foamed container can be determined by the same method as in the case of the foamed sheet. The color of the obtained foamed container was the same as that of the foamed sheet.

The thermoplastic polyester resin foamed container of the present invention may have a non-foamed resin layer on the inner surface. By having a non-foamed resin layer, the strength of the foamed container is improved and it is not easily deformed by heat.

In addition, it is also possible to construct a structure in which a printed layer is sandwiched between two non-foamed resin layers and laminated on the inner surface of the foamed container. With such a configuration, the surface of the foamed container can be colored and decorated, so that the design of the pattern is improved.

The thermoplastic polyester-based resin foaming container of the present invention is used as a container such as a household appliance packaging container, a mechanical parts packaging container, and a food packaging container. It is especially useful as a food packaging container. Among them, ovens and microwave ovens are preferred.

Further, it is particularly preferably a refrigerated microwave heating container for food such as gratin, lasagna, etc., which is burned and eaten by heating in a microwave oven after circulating in a refrigerated or frozen state.

In addition, the so-called freezing microwave heating refers to heating and conditioning of frozen food using a microwave oven.

    [Example]    

Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited by the following description. In addition, "part" used as a unit of the raw material composition below means "part by mass" as long as it is not particularly limited.

[Example 1]

(Manufacture of foamed sheet)

100 parts by mass of a PET resin having an IV value of 1.04 as a main raw material (hereinafter also referred to as 100 "parts", etc.), 1.0 part of fine talc (SG-95 manufactured by Japan Talc Corporation) as a crystallization accelerator, and cross-linking 0.2 parts of pyromelite dianhydride (Daicel pyromelite dianhydride manufactured by Daicel). The raw materials were dehumidified and dried at 100 ° C for 4 hours in advance, A 90 mm extruder performs melt-kneading, and presses nitrogen at a predetermined position to perform the kneading. Then from the caliber A 135 mm round mold was extruded, and while being cooled with a predetermined mandrel, it was formed into a sheet shape and rolled up.

The thickness of the obtained foamed sheet was 0.75 mm and the basis weight was 330 g / m ² .

(Manufacture of foam container)

The thermoplastic polyethylene terephthalate resin foamed sheet was preheated in a heater tank at 150 ° C for 90 seconds, so that the surface temperature of the foamed sheet became 125 ° C.

Subsequently, compressed air was supplied from the male mold side, the foamed sheet was closely adhered to the male mold, the male mold and the female mold were closed for 6 seconds, and vacuum pressure forming was performed at 180 ° C. to obtain a foamed container.

[Example 2]

A foamed sheet and a foamed container were produced in the same manner as in Example 1 except that 1.0 part of general-purpose talc (MS-P manufactured by Japan Talc Corporation) was used as a crystallization accelerator.

[Example 3]

In addition to using 5 parts of PE-SM-SAE 6100 BLACK-C (30% by weight) blended with furnace carbon black (hereinafter referred to as “CB”) PE-SM-SAE 6100 BLACK-C (1.5 for CB addition) Parts) A foamed sheet and a foamed container were produced in the same manner as in Example 1 except for being a crystallization accelerator.

[Example 4]

A foamed sheet was produced in the same manner as in Example 1 except that 0.5 part of sodium octadecanoate (hereinafter also referred to as "Na-octadecanoic acid", NS-8 manufactured by Nitto Chemical Industries, Ltd.) was used as a crystallization accelerator. And foaming containers. The aggregation diameter was observed by TEM and SEM, but it was not confirmed (dissolved).

[Example 5]

A foamed sheet and a foamed container were produced in the same manner as in Example 1 except that 100 parts of a PET resin having an IV value of 0.88 was used as a main raw material.

[Example 6]

In addition to using 100 parts of PET resin with an IV value of 0.88 as the main raw material and 1.0 part of high apparent density talc (hereinafter also referred to as "high-density talc", MS-KY manufactured by Japan Talc Corporation) as a crystallization accelerator, A foamed sheet and a foamed container were produced in the same manner as in Example 1.

[Examples 7 to 12]

A foamed sheet and a foamed container were produced in the same manner as in Example 1 except that the crystallization accelerators shown in Tables 1 and 2 were used in parts by mass shown in Tables 1 and 2. In the table, "/" in Examples 8 and 10 indicates that talc and furnace carbon black were used in combination as a crystallization accelerator.

[Comparative Example 1]

A foamed sheet and a foamed container were produced in the same manner as in Example 1 except that 1.0 part of high apparent density talc (MS-KY manufactured by Japan Talc Corporation) was used as a crystallization accelerator.

[Comparative Example 2]

In addition to using 1 part of PE-SM-SAE 6100 BLACK-C (0.3 part in terms of CB addition amount) made by Daiichi Sho Chemical Industry Co., Ltd. with 30% by mass of furnace carbon black blended as the crystallization accelerator, A foamed sheet and a foamed container were produced in the same manner as in Example 1.

[Comparative Example 3]

A foamed sheet and a foamed container were produced in the same manner as in Example 1 except that 0.1 part of general-purpose talc (MS-P manufactured by Japan Talc Corporation) was used as a crystallization accelerator.

Each measurement and evaluation were performed with respect to the produced foamed sheet and the foamed container, and the results are shown in Tables 1 and 2.

[Determination of particle size of crystallization accelerator in foamed sheet]

(SEM observation)

SEM observations were performed on Examples 1, 2, 5, and 6, and Comparative Examples 1, 3 using talc as a crystallization accelerator.

Use a razor to cut the sample, attach the ribbon to the sample table, and load the sample on it. The reflection electron detector of the "S-3400N" scanning electron microscope manufactured by Hitachi High-Technologies Co., Ltd. was used to photograph the sample at a low vacuum (60 Pa).

Shoot at 1000x magnification.

(TEM observation)

TEM observation was performed on Example 3 and Comparative Example 2 using furnace carbon black as a crystallization accelerator.

A foamed sheet was cut out using a cutter as a measurement sample. The cut sample was fixed on a sample table for low temperature using an adhesive, and then an ultra-thin slicer (Ultramicrotome, manufactured by LEICA MICROSYSTEMS) and a frozen section production system (manufactured by LEICA MICROSYSTEMS) were used to produce ultra-thin sections (thickness: 90 nm).

Next, an ultra-thin slice was photographed at a magnification of 20,000 times using a TEM (H-7600 manufactured by Hitachi High-Technologies Corporation).

In addition, in Example 4 in which the crystallization accelerator was not granular, the particle diameter could not be measured.

(Measurement of particle size)

The TEM observation and the SEM observation are performed by photographing 20 primary particles and agglomerates for each sample, and measuring the particle diameter and diameter of each sample to calculate the average value of these. The results are shown in Table 1.

[Determination of Particle Size of Crystallization Accelerator in Foaming Container]

A SEM observation, a TEM observation, and a particle diameter measurement were performed in the same manner as in the case of the foamed sheet, except that the bottom surface of the foamed container was cut out using a cutter to measure the sample.

[Measurement of the existence ratio of molecules with a molecular weight of 10,000 or less]

Samples were prepared according to the following sample production method, and molecular weights were measured under the following measurement conditions using the following measuring device. Let the area of the curve of the differential molecular weight distribution obtained from the measurement result be 100%, and when it is taken as 100% by mass (total mass), the area corresponding to "the molecular weight of the polyester-based resin of 10,000 or less The ratio (existence ratio) is calculated as mass%. In addition, the ratio (mass%) to the "area of a molecule having a molecular weight of 10,000 or less" is an integrated molecular weight distribution (vertical axis: area, horizontal axis: Log ₁₀ M (M = "Molecular weight)"), the "area of the position with a molecular weight of 10,000" is taken as the "existence ratio (mass%) of molecules with a molecular weight of 10,000 or less".

(Sample production method)

5 mg of the obtained foamed sheet was taken as a sample, and the solvent was added to the sample in the order of 0.5 mL of HFIP and 0.5 mL of chloroform, and gently shaken, and left for 5 hours. After confirming the dissolution, the solution was diluted by adding chloroform to 10 mL, and after gently shaking, it was measured by filtration using a non-aqueous 0.45 μm syringe filter (manufactured by Shimadzu GLC).

Dipping time: 24.0 ± 2.0hr (completely dissolved).

Comparative samples: SRM706a, MS-311, TR-8580.

(Measuring device)

GPC device: HLC-8320GPC (built-in RI detector and UV detector) manufactured by TOSOH.

Protection column: TOSOH TSK protection column Hxl-H (6.0mmI.D. × 4cm) × 1 branch.

Column (reference): TOSOH TSKgel SuperH-RC (6.0mmI.D. × 15cm) × 2 pieces.

Column (sample): TOSOH TSKgel GMHxl (7.8mmI.D. x 30cm) x 2 pieces.

(Measurement conditions)

Column temperature: 40 ° C.

Detector temperature: 40 ° C.

Pump injection temperature: 40 ° C.

Solvent: chloroform.

Flow rate (reference): 0.5 mL / min.

Flow rate (sample): 1.0 mL / min.

Implementation time: 26min.

Data accumulation time: 10 to 25 min.

Data interval: 500msec.

Injection volume: 15 μL (sample and TR-8580) / 50 μL (ShodexA‧B, SRM706a, MS-311).

Detector: UV = 254nm.

[Determination of crystallization time of foamed sheet at 110 ° C]

A sample was taken from the obtained foamed sheet, and DSC measurement was performed under the following measurement conditions using the following measurement device. From the DSC curve obtained during the second heating, the time from "the time when the second heating is started" to "the time when the peak of the heat generation peak displayed at the latest time" is obtained, As the crystallization time.

(Measuring device)

DSC device: Differential scanning calorimeter device DSC7000X (manufactured by Hitachi High-Tech Science).

(Measurement conditions)

Sample volume: 5.5 ± 0.5mg.

Reference (alumina) amount: 5 mg.

Nitrogen flow: 20mL / min.

Number of trials: 2.

First temperature rise: The temperature was raised from 30 ° C to 290 ° C at a heating rate of 100 ° C / minute, and the temperature was maintained at 290 ° C for 10 minutes.

‧Setting value of temperature rising start temperature: 30 ° C.

‧The set value of the end temperature rise: 290 ° C.

‧Setting value of heating rate: 100 ° C / min.

‧Set value of holding time at the end of temperature rise: 10 minutes.

Cooling method: Take out from the measuring device, leave it to stand at 23 ° C for 10 minutes, and then return to the measuring device at 30 ° C.

Second temperature increase: The temperature was raised from 30 ° C to 110 ° C at a heating rate of 100 ° C / minute, and the temperature was maintained at 110 ° C for 30 minutes.

‧Setting value of temperature rising start temperature: 30 ° C.

‧The set value of the end temperature rise: 110 ℃.

‧Setting value of heating rate: 100 ° C / min.

‧Set value of holding time at the end of temperature rise: 30 minutes.

(How to make DSC curve)

From "start the second temperature increase" to "the end of the holding time of the temperature rise end temperature", read the thermal DSC every 0.2 seconds, with time (minutes) as the horizontal axis and thermal DSC (mW) as the vertical axis Plot to create a DSC curve (Figure 1).

(Specific method for the peak of the heating spike displayed at the latest time)

In the DSC curve (Fig. 1), point A in Fig. 1 is set as "the peak of the heating peak displayed at the latest time".

[Determination of crystallization time of foaming container at 110 ° C]

Except that a sample was taken from the bottom surface of the obtained foamed container, a measurement DSC measurement was performed in the same manner as in the case of the foamed sheet to determine the crystallization time.

[Quantitative method of crystallization accelerator in foamed sheet]

<Identification method of talc>

A sample was taken from the bottom surface of the obtained foamed container, and the sample was subjected to ashing using the following measuring device, and then the following measuring device was used. The identification of talc was performed under the conditions.

(Measuring device)

‧Phoenix microwave oven (manufactured by CEM).

(Ashing method)

‧ Put 1.0g of sample into the above device, and perform ashing for 30 minutes under the following conditions.

Ashing conditions: DWELL TIME = 30min, OPERATING TEMP = 800 ℃

(Identification method)

(Measuring device)

‧Fourier conversion infrared spectrophotometer Nicolet iS10 (manufactured by Thermo SCIENTIF).

‧Single reflection type horizontal ATR (manufactured by Thermo Corporation) Smart-iTR (crystal = Diamond with ZnSe lens, angle = 42 °).

(test methods)

‧The ashed sample was directly subjected to IR measurement by a one-shot reflection ATR method (= micro surface area analysis method). The quality species are estimated from the obtained difference spectrum chart.

<Ash content measurement>

Samples were taken from the bottom surface of the foamed sheet whose components were identified as talc after ashing, and the ash content was determined as the amount of talc under the following measurement conditions using the following measuring device.

(Measuring device)

‧Phoenix microwave oven (manufactured by CEM).

‧Analytical electronic balance GR-200 (manufactured by A & D Co., Ltd.).

(Ashing method)

‧ Put a container containing 1.0 g of sample into the above device, and perform ashing for 30 minutes under the following conditions.

Ashing conditions: DWELL TIME = 30min, OPERATING TEMP = 800 ℃

(Calculation method)

Ash content (% by mass) = ((weight of container after ashing)-(weight of container only)) / (sample (weight of foamed sheet = 1.0g)) × 100

(Unit conversion)

Ash content (mass parts) = ash content (mass%) / {100 (mass% of foamed sheet)-ash content (mass%)} × 100

<Differential thermal and thermogravimetric simultaneous measurement (TG / DTA)>

A sample was taken from the bottom surface of the obtained foamed sheet, and the amount of carbon black in the foamed sheet was determined using the following measuring device under the following measurement conditions.

(Measuring device)

‧Differential thermogravimetric simultaneous measurement device TG / DTA6200 (manufactured by SII Nano Technology).

(test methods)

The sample was allowed to stand in a thermostatic bath at 120 ° C. for 2 hours to remove the foaming agent and the organic solvent from the resin. In the case of foamed sheets, foamed containers, etc. containing a foaming agent and an organic solvent in the resin, the foaming agent and the organic are removed from the resin by standing in a thermostatic bath at 120 ° C for 2 hours. A solvent was used as a measurement sample.

The sample was filled with about 15 mg of a sample so that a gap was not formed in the bottom of a platinum measurement container, and measurement was performed using alumina as a reference substance. In terms of temperature, the temperature was raised from 30 ° C to 520 ° C at a rate of 10 ° C / min and a nitrogen flow rate of 230mL / min, and then increased from 520 ° C to 800 ° C at a rate of 10 ° C / min and an air flow rate of 160mL / min. until. A TG curve (vertical axis: TG (%), horizontal axis: temperature (° C)) was obtained, and based on the curve, a weight loss component of the sample weight when the temperature was raised from 520 ° C to 800 ° C was calculated as the carbon black amount (mass% ).

(Unit conversion)

Amount of carbon black (parts by mass) = Amount of carbon black (% by mass) / {100 (% by mass of foamed sheet)-Amount of carbon black (% by mass)} × 100

<Fluorescent X-ray measurement>

A sample was taken from the bottom surface of the obtained foamed sheet, and the mass of zinc metal was determined under the following measurement conditions using the following measuring device, and the amount of zinc oxide in the foamed sheet was determined by converting the mass to zinc oxide.

(Measuring device)

‧Equipment: A fluorescent X-ray analyzer RIX-2100 manufactured by Rigaku Co., Ltd.

‧ Between X-rays: Vertical Rh = 3kw.

(Measurement conditions)

‧Slit width: standard.

‧Spectral crystallization: TAP (F to Mg), PET (AL, Si), LiF (K to U), F-PC (F to Ca), SC (Ti to U).

‧Measurement mode: FP film method (Zn-PET).

‧Balance measurement: Yes (polyethylene terephthalate).

(test methods)

‧Cut a sample of 3 cm from each of the obtained foamed sheets and measure the weight. Then convert the basis weight, attach the carbon double-sided tape to the carbon pedestal, set the balance component to polyethylene terephthalate, and analyze by order analysis).

(Conversion formula)

‧ Set the balance component to polyethylene terephthalate, and recalculate it on a computer so that the total becomes 100% by weight, and calculate the mass% of the metal monomer.

‧Convert the mass% of the obtained metal into an oxidized metal according to the following formula.

Oxidized metal (mass%) = [(mass% of metal monomer) × {atomic weight of metal (g / mol) +16 (atomic weight of oxygen (g / mol)}) / atomic weight of metal (g / mol)

The organic acid salt-based crystallization accelerator is converted in accordance with the following formula.

Organic acid salt (% by mass) = [(% by mass of metal monomer) x {atomic weight of metal (g / mol) + molecular weight of organic acid (g / mol) -1 (atomic weight of hydrogen)}) / atomic weight of metal (g / mol)

(Unit conversion)

Amount of oxidized metal or organic acid salt (mass parts) = {Amount of oxidized metal or organic acid salt (mass%)} / [100 (mass% of foamed sheet)-{Amount of oxidized metal or organic acid salt (mass%)} ] × 100

[Quantitative method of crystallization accelerator in foaming container]

Except that a sample was taken from the bottom surface of the obtained foamed container, the operation was performed in the same manner as in the case of the foamed sheet, and the content of the crystallization accelerator in the foamed container was determined.

[Determination of heat of crystallization of foamed sheet or foamed container]

A sample was taken from the obtained foamed sheet or the bottom surface of the foamed container, and a DSC measurement was performed in accordance with JIS K7122 under the following measurement conditions using the following measuring device to determine the heat of crystallization.

(Measuring device)

DSC device: Differential scanning calorimeter device DSC7000X (manufactured by Hitachi High-Tech Science).

(Measurement conditions)

Sample volume: 5.5 ± 0.5mg.

Reference (alumina) amount: 5 mg.

Nitrogen flow: 20mL / min.

Number of trials: 2.

[Calculation of Crystallization Degree of Foaming Container]

From the melting heat and crystallization heat of the DSC curve obtained in the above [Measurement of the crystallization heat of the foamed sheet or the foaming container], the degree of crystallization was calculated according to the following formula (1).

Degree of crystallization (%) = {(absolute value of heat of fusion (J / g)-absolute value of heat of crystallization (J / g)) ÷ heat of complete crystallization (J / g)} × 100. ． ． (1)

[Calcination test]

The lengths of the long and short sides of the obtained foamed container were measured using a slide rule, and then heated and calcined in an oven at 200 degrees for 10 minutes. Thereafter, the container was taken out, and the dimensions of the long side and the short side were measured again, and the dimensional change before and after heating was calculated according to the following formulae (2a) and (2b). The average value of the dimensional change amount of the long side and the short side was calculated according to the following formula (3) as the dimensional change rate [%] after firing, and evaluated based on the following evaluation criteria.

Long side dimension change [%] = {(size of long side after heating)-(size of long side before heating)} / (size of long side before heating) × 100. ． ． (2a)

Short side dimension change [%] = {(size of short side after heating)-(size of short side before heating)} / (size of short side before heating) × 100. ． ． (2b)

Dimensional change rate after calcination [%] = {(absolute value of dimensional change amount of long side) + (absolute value of dimensional change amount of short side)} / 2. ． ． (3)

(Evaluation criteria)

★: The dimensional change rate is less than 2.0%.

：: The dimensional change rate is 2.0% or more and less than 2.5%.

○: The dimensional change rate is 2.5% or more and less than 2.7%.

△: The dimensional change rate is 2.7% or more and less than 3.0%.

×: The dimensional change rate is 3.0% or more.

[Dynatup (registered trademark) shock test]

Evaluation was performed in accordance with ASTM D-3763 "Standard Test Method for High Speed Puncture Properties of Plastics Using Load and Displacement Sensors". The test conditions are as follows.

The test piece was cut into 10 cm squares at 5 points in the width direction of the foamed sheet, and was aged at 23 ° C. for 16 hours. Its total absorbed energy is 1.0J or more, and it has excellent impact resistance.

(Test conditions, etc.)

Test device: Dynatup punch test device GRC 8250 (manufactured by General Research Corp.).

Test piece: 100 x 100 x original thickness (mm).

Span (span): 76mm line in a circular hole

Test speed: 1.52m / s.

Test temperature: 23 ° C.

Drop height (stopper position): 56cm.

Drop weight distance: 12cm.

Test load: 3.17kg.

Number of trials: 5.

By the automatic calculation of the aforementioned device, the integral value of the graph obtained after the measurement is calculated.

[Freezing drop test]

250 mL of water was added to the obtained foaming container, and frozen in an environment at -20 ° C for 16 hours to prepare a test body. This test body was dropped from a height of 70 cm, and the damage condition of the foamed container was visually confirmed and evaluated as follows. From ◎ to ○, the foamed container system has excellent cold brittleness resistance.

：: No cracking occurred in the foamed container.

○: Although cracks occur in the foamed container, fine fragments are not scattered.

×: A crack was generated in the foamed container, and fine fragments were scattered.

From the results shown in Tables 1 and 2, it can be seen that the dimensional change rates of the Examples 1 to 12 systems after the application of the present invention are all less than 3% after calcination, and have high heat resistance.

In addition, it can be seen that in Examples 1 to 12 to which the present invention is applied, since the crystallization time at 110 ° C. is less than 14 minutes, the time required for the forming step is shortened and the productivity of the foamed container is improved.

In addition, it can be seen that Examples 1 to 12 to which the present invention is applied have values of total absorbed energy in the Dynatup shock test of 0.8 [J] or more, and also have excellent cold brittleness resistance.

On the other hand, in Comparative Examples 1 to 3 where the crystallization time at 110 ° C. was longer than 14 minutes, the dimensional change rate after calcination was 3%, and no improvement in heat resistance was observed.

It is understood that the use of the thermoplastic polyester-based resin foamed sheet of the present invention can obtain a container having high heat resistance and improve the productivity of the container.

Claims (13)

    A thermoplastic polyester resin foamed sheet comprising a thermoplastic polyester resin and one or more crystallization accelerators selected from the group consisting of an inorganic crystallization accelerator and an organic crystallization accelerator; The crystallization time measured for the polyester resin foamed sheet using the following measurement method is 14 minutes or less; <Measuring method> A measurement sample is taken from the thermoplastic polyester resin foamed sheet, and measured using a heat flux differential scanning calorimetry (DSC) device, heating the measurement sample at a heating rate of 100 ° C / min from 30 ° C to 290 ° C for the first time, and holding it at 290 ° C for 10 minutes; secondly, taking the measurement sample out of the measurement device, After standing at 23 ° C for 10 minutes, it was returned to the measurement device at 30 ° C. The temperature was raised a second time from 30 ° C to 110 ° C at a heating rate of 100 ° C / minute and held at 110 ° C for 30 minutes. In the DSC curve obtained at the second temperature increase, the time from the time when the second temperature increase is started to the time when the peak of the heat generation peak displayed at the latest time is taken as the crystallization time.         The thermoplastic polyester-based resin foamed sheet according to item 1 of the scope of the patent application, wherein the crystallization promoter is granular, and the crystallization promoter in the thermoplastic polyester-based resin foamed sheet is The major axis of the particle diameter is 50 μm or less.         The thermoplastic polyester-based resin foamed sheet according to item 1 of the scope of the patent application, wherein the crystallization accelerator contains at least one selected from the group consisting of talc, carbon black, and a metal oxide.         The thermoplastic polyester resin foamed sheet according to item 1 of the scope of the patent application, wherein the content of the crystallization accelerator is 0.05 mass parts or more and 5 masses relative to 100 mass parts of the thermoplastic polyester resin. The following.         The thermoplastic polyester resin foamed sheet according to item 1 of the scope of the patent application, wherein the existence ratio of molecules having a molecular weight of 10000 or less expressed by a differential molecular weight distribution in the thermoplastic polyester resin is relative The total mass of the thermoplastic polyester resin is 6.0% by mass or less.         The thermoplastic polyester resin foamed sheet as described in item 1 of the scope of the patent application is for food packaging containers.         A thermoplastic polyester resin foaming container comprising a thermoplastic polyester resin and one or more crystallization accelerators selected from the group consisting of inorganic crystallization accelerators and organic crystallization accelerators; The crystallization time measured for the polyester-based resin foamed container using the following measurement method is 14 minutes or less; <Measurement method> A measurement sample is taken from the thermoplastic polyester-based resin foamed container and measured using a heat flux differential scanning calorimetry (DSC) device, heating the measurement sample at a heating rate of 100 ° C / min from 30 ° C to 290 ° C for the first time, and holding it at 290 ° C for 10 minutes; secondly, taking the measurement sample out of the measurement device, After standing at 23 ° C for 10 minutes, it was returned to the measurement device at 30 ° C. The temperature was raised a second time from 30 ° C to 110 ° C at a heating rate of 100 ° C / minute and held at 110 ° C for 30 minutes. In the DSC curve obtained at the second temperature increase, the time from the time when the second temperature increase is started to the time when the peak of the heat generation peak displayed at the latest time is taken as the crystallization time.         The thermoplastic polyester resin foaming container according to item 7 of the scope of the patent application, wherein the crystallization accelerator is granular, and the crystallization accelerator in the thermoplastic polyester resin foaming container is The major axis of the particle diameter is 50 μm or less.         The thermoplastic polyester-based resin foaming container according to item 7 of the scope of the patent application, wherein the crystallization accelerator contains at least one selected from the group consisting of talc, carbon black, and a metal oxide.         The thermoplastic polyester resin foaming container according to item 7 of the scope of the patent application, wherein the content of the crystallization accelerator is 0.05 mass parts or more and 5 masses relative to 100 mass parts of the thermoplastic polyester resin. The following.         The thermoplastic polyester resin foaming container according to item 7 of the scope of the patent application, wherein the existence ratio of molecules having a molecular weight of 10000 or less expressed by a differential molecular weight distribution in the thermoplastic polyester resin is relative The total mass of the thermoplastic polyester resin is 6.0% by mass or less.         The thermoplastic polyester resin foaming container as described in item 7 of the scope of application for patent, is a food packaging container.         The thermoplastic polyester resin foaming container according to item 7 of the scope of the patent application is a refrigerated microwave heating container.