JP6176964B2 - Resin foam sheet and molded body - Google Patents

Description

 The present invention relates to a resin foam sheet and a molded body.

A foam sheet (resin foam sheet) formed by foaming a polystyrene-based resin or the like is often used as a raw material for a container or the like for containing food or the like. The molded body of the resin foam sheet has features that it is lightweight, has high heat insulation, has high strength and is difficult to break.
A container formed from a resin foam sheet using a general-purpose polystyrene resin has a problem that it is easily deformed when heated by a microwave oven or the like because it is not sufficiently high in heat resistance. For this reason, as a polystyrene-based resin foam sheet that can withstand heat cooking using a microwave oven, one using a heat-resistant polystyrene-based resin has been developed.
However, a foam sheet using a conventional heat-resistant polystyrene resin is more brittle than a foam sheet using a general-purpose polystyrene resin. For this reason, a foam sheet using a heat-resistant polystyrene-based resin may be broken during production by an extrusion foaming method or the like, or may be broken when a container is molded from a foamed sheet by a heat molding method. It was bad.

For such problems, for example, a styrene-based heat-resistant resin foam sheet based on a heat-resistant polystyrene-based resin and a specific amount of styrene-butadiene copolymer resin has been proposed (Patent Document 1).
Alternatively, for example, a heat resistant polystyrene resin foam laminated sheet having a laminated structure of a polystyrene resin foam layer containing a polystyrene resin and a heat resistant polystyrene resin foam layer containing a polystyrene resin and a polyphenylene ether resin has been proposed. (Patent Document 2).

JP-A-8-41233 JP 2012-6354 A

However, although the techniques of Patent Documents 1 and 2 can improve the productivity of a foam sheet having heat resistance, there is a problem that a molded body molded from the foam sheet cannot obtain sufficient impact resistance. .
Then, this invention aims at the resin foam sheet which is excellent in heat resistance and excellent in impact resistance.

The resin foam sheet of the present invention is obtained by foaming a resin containing a polystyrene resin and a polyphenylene ether resin, and contains 10 to 50 parts by mass of the polyphenylene ether resin with respect to 100 parts by mass of the resin. The rubber content is 1.0 to 10.0 parts by mass with respect to 100 parts by mass of the polyphenylene ether resin.
The thickness ratio is 500 μm or more, and the density ratio represented by [density at a thickness of 200 μm from the surface] / [total density] is preferably 1.5 to 2.5, and the total density is More preferably, it is 0.05-0.25 g / cm < ³ >.

  The molded body of the present invention is formed by molding the resin foam sheet of the present invention.

  The resin foam sheet of the present invention is excellent in heat resistance and excellent in impact resistance.

It is a schematic diagram which shows an example of the manufacturing apparatus of a foam sheet.

(Resin foam sheet)
The resin foam sheet of the present invention (hereinafter sometimes simply referred to as a foam sheet) is referred to as a polystyrene resin (hereinafter also referred to as (A) component) and a polyphenylene ether resin (hereinafter referred to as (B) component). And a rubber component.

<(A) component: polystyrene resin>
The component (A) is a polystyrene resin. Examples of the component (A) include homopolymers of styrene monomers such as styrene, α-methylstyrene, vinyltoluene, chlorostyrene, ethylstyrene, i-propylstyrene, dimethylstyrene, and bromostyrene, or copolymers thereof. A copolymer of a styrene monomer as a main component (50% by mass or more) and a styrene monomer and a vinyl monomer that can be polymerized therewith: a copolymer of a styrene monomer and a rubber component such as butadiene, or a styrene Examples include homopolymers of monomers, copolymers of these, copolymers of styrene monomers and vinyl monomers, and mixtures or polymers of diene rubbery polymers, so-called high impact polystyrene.
Examples of vinyl monomers that can be polymerized with styrenic monomers include alkyl (meth) acrylates such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, and cetyl (meth) acrylate, (meth) acrylonitrile, Examples thereof include bifunctional monomers such as dimethyl maleate, dimethyl fumarate, diethyl fumarate, ethyl fumarate, divinylbenzene, and alkylene glycol dimethacrylate. These vinyl monomers may be used individually by 1 type, and may be used in combination of 2 or more type.
Examples of the diene rubber-like polymer include polybutadiene, styrene-butadiene copolymer, ethylene-propylene-nonconjugated diene three-dimensional copolymer, acrylonitrile-butadiene-styrene copolymer, and the like.
These (A) components may be used individually by 1 type, and may be used in combination of 2 or more type.

The component (A) may be a polystyrene resin that is not a recycled material, such as a commercially available polystyrene resin, a polystyrene resin newly prepared by a method such as a suspension polymerization method, or a polystyrene resin that is a recycled material. Good.
Examples of the recycled raw materials include those obtained by collecting used polystyrene-based resin foamed molded articles such as fish boxes, home appliance cushioning materials, food packaging trays, etc., and regenerating them using a limonene dissolution method or a heating volume reduction method. Recyclable raw materials that can be used include home appliances (eg, TVs, refrigerators, washing machines, air conditioners, etc.) and office work in addition to those obtained by reprocessing used polystyrene resin foam moldings. Non-foamed polystyrene-based resin moldings that have been separated and collected from industrial machines (for example, copiers, facsimiles, printers, etc.) are pulverized, melt-kneaded, and repelletized.

  The content of the component (A) in the foamed sheet is preferably 50 to 90 parts by weight, more preferably 60 to 90 parts by weight, and still more preferably 70 to 90 parts by weight with respect to 100 parts by weight of the resin constituting the foamed sheet. . If the amount is less than the above lower limit, the resulting foamed sheet may become brittle, and the handleability of the molded container may be reduced. If the amount exceeds the upper limit, the content of the component (B) decreases and heat resistance is poor. May be sufficient.

<(B) component: polyphenylene ether resin>
The component (B) is a polyphenylene ether resin. The foam sheet exhibits excellent heat resistance by containing the component (B).

  Examples of the component (B) include compounds represented by the following formula (I).

(I) In formula, R < ¹ > and R < ² > shows a C1-C4 alkyl group or a halogen atom each independently. Examples of the halogen atom include fluorine, chlorine, bromine and the like.
In formula (I), n is a positive integer representing the degree of polymerization. For example, n is usually 10 to 5000.

  Examples of the component (B) represented by the formula (I) include poly (2,6-dimethylphenylene-1,4-ether), poly (2,6-diethylphenylene-1,4-ether), and poly (2,6-dichlorophenylene-1,4-ether) and the like.

  Content of the (B) component in a foamed sheet is 10-50 mass parts with respect to 100 mass parts of resin which comprises a foamed sheet, 10-40 mass parts is preferable, and 10-30 mass parts is more preferable. If it is less than the said lower limit, the heat resistance of the foam sheet obtained is inadequate, and even if it exceeds the said upper limit, there exists a possibility that the improvement of further heat resistance may not be aimed at.

<Rubber>
The foam sheet contains a rubber component. By containing rubber, it has excellent impact resistance. In addition, it is possible to prevent breakage during the production of the foam sheet and the production of the molded body.

The rubber component in the foamed sheet may be, for example, a rubber component derived from high impact polystyrene used as the component (A), or a rubber component derived from a diene rubber-like polymer compounded separately from the component (A). But you can.
The diene rubber-like polymer compounded separately from the component (A) includes polybutadiene, styrene-butadiene copolymer, ethylene-propylene-nonconjugated diene three-dimensional copolymer, acrylonitrile-butadiene-styrene copolymer. Etc.

  The rubber content in the foamed sheet is determined in consideration of the content of the component (B), and is preferably 0.2 to 2.0 parts by weight with respect to 100 parts by weight of the resin constituting the foamed sheet. 0.3 to 1.8 parts by mass is more preferable. If it is less than the lower limit, the impact resistance may be lowered, and if it exceeds the upper limit, the foamed sheet becomes soft and the strength of the molded product obtained by molding may be lowered.

  Moreover, 1.0-10.0 mass parts is preferable in the resin which comprises a foamed sheet with respect to 100 mass parts of (B) component, 1.5-8.0 mass parts is more preferable, 2.0-6.0 mass parts is further more preferable. If it is less than the said lower limit, the impact resistance of a foam sheet cannot be improved and it will become easy to fracture | rupture during manufacture. If it exceeds the upper limit, the heat resistance of the foamed sheet is lowered.

<Optional component>
Foamed sheets are foam nucleating agents, nucleating agents, deodorants, ultraviolet absorbers, antioxidants, colorants, lubricants, flame retardants, antistatic agents and other additives (A) to (B) described above. Arbitrary components, such as resin other than (optional resin), can be contained.

  The type of additive is determined in consideration of physical properties required for the foam sheet. The above-mentioned additives may be used alone or in combination of two or more.

Optional resins include homopolymers of olefinic monomers such as ethylene and propylene, or copolymers thereof, copolymers of olefinic monomers and vinyl monomers that can be polymerized with olefinic monomers as the main component, etc. And other polyolefin-based resins.
Arbitrary resin may be used individually by 1 type, and 2 or more types may be combined and used for it.

  Although content of arbitrary resin in resin which comprises a foam sheet is not specifically limited, 20 mass parts or less are preferable with respect to 100 mass parts of polystyrene-type resins, 10 mass parts or less are more preferable, and 0 mass parts may be sufficient. If it is below the said upper limit, the foamed sheet obtained will not become weak, and the handleability of the shape | molded container will be improved.

  The thickness of the foamed sheet is determined in consideration of the use of the foamed sheet. For example, when used for a container for food use, the thickness is preferably 500 to 4000 μm, more preferably 1000 to 2500 μm.

Foamed sheet overall density (hereinafter, sometimes referred to overall density) is not particularly limited, for example, preferably 0.05~0.25g / cm ^3, more preferably 0.06~0.22g / cm ³ . If the overall density is not less than the above lower limit value, the strength of the foamed sheet can be further improved, and if it is not more than the above upper limit value, the heat insulating property of the foam sheet can be further improved.

In the foamed sheet, the density of the surface layer portion (thickness portion of 200 μm from the surface) (hereinafter sometimes referred to as surface layer density) is preferably larger than the overall density. When the surface layer density is larger than the overall density, the impact resistance of the foamed sheet can be further increased.
The surface layer portion having a density larger than the overall density may be formed on one surface of the foam sheet, or may be formed on both surfaces, from the viewpoint of further improving the impact resistance of the foam sheet. It is preferably formed on both sides of the sheet.
The surface density is the cooling of the foamed foam that is extruded and foamed, such as by adjusting the temperature and air volume of the cooling air in the manufacturing method described later, or by adjusting the temperature of the circular die or the cooling temperature of the mandrel. By adjusting the speed, it is adjusted to an arbitrary range.

  The ratio represented by [surface layer density] / [total density] (hereinafter sometimes referred to as surface layer density ratio) is preferably 1.5 to 2.5, and more preferably 1.8 to 2.2. If the surface layer density ratio is not less than the above lower limit value, it is possible to further improve the impact resistance of the foam sheet. A good molded product is obtained.

  Although the midpoint glass transition temperature (Tmg) of a foam sheet is not specifically limited, For example, 110 degreeC or more is preferable and 115 degreeC or more is more preferable. If it is more than the said lower limit, sufficient heat resistance is exhibited with respect to the cooking by a microwave oven.

(Method for producing foam sheet)
The foam sheet is manufactured by a conventionally known manufacturing method.
An example of the foam sheet manufacturing method will be described below with reference to the drawings.
The foamed sheet manufacturing apparatus 1 in FIG. 1 is an apparatus that obtains a foamed sheet by extrusion molding, and includes an extruder 10, a foaming agent supply source 18, a circular die 20, a mandrel 30, and two winders 40. Is provided.
The extruder 10 is a so-called tandem extruder, and has a configuration in which a first extrusion portion 11 and a second extrusion portion 12 are connected by a pipe 16. The first extrusion unit 11 includes a hopper 14, and a foaming agent supply source 18 is connected to the first extrusion unit 11.
A circular die 20 is connected to the second extruding part 12, and a mandrel 30 including a cutter 32 is provided downstream of the circular die 20. A cooling blower (not shown) is provided between the circular die 20 and the mandrel 30.

First, the raw material which comprises a foam sheet is thrown into the 1st extrusion part 11 from the hopper 14. FIG. The raw material charged from the hopper 14 is a resin constituting the foamed sheet, and a foam nucleating agent, a nucleating agent, a deodorant, an ultraviolet absorber, an antioxidant, a colorant, a lubricant, a difficult to be blended as necessary. It is an optional component such as a flame retardant and an antistatic agent.
Examples of the foam nucleating agent include talc, sodium hydrogen carbonate, ammonium hydrogen carbonate, calcium carbonate, clay, citric acid and the like, and among these, talc is more preferable. Although the compounding quantity of a foam nucleating agent is not specifically limited, 0.01-5 mass parts is preferable with respect to 100 mass parts of resin which comprises a foamed sheet.
Examples of the deodorizer include inorganic particles such as silica-based, zeolite-based, and zirconium phosphate-based materials, and calcined hydrotalcite. The deodorant has an effect of reducing the odor peculiar to polyphenylene ether.
As for the compounding quantity of a deodorizer, 0.05-20 mass parts is preferable with respect to 100 mass parts of resin which comprises a foamed sheet.

In the 1st extrusion part 11, it mixes, heating a raw material to arbitrary temperature, it is set as a resin melt, a foaming agent is supplied to the 1st extrusion part 11 from the foaming agent supply source 18, and a foaming agent is supplied to a resin melt. To make a mixture.
The heating temperature is appropriately determined within a range in which the resin is melted and the foamed layer optional component is not denatured in consideration of the type of the resin.

Examples of the blowing agent include hydrocarbons such as propane, butane, and pentane, and halogenated hydrocarbons such as tetrafluoroethane, chlorodifluoroethane, and difluoroethane. Of these, butane is preferable. As butane, normal butane or isobutane may be used alone, or normal butane and isobutane may be used in any proportion. These foaming agents may be used individually by 1 type, and may be used in combination of 2 or more type.
The blending amount of the foaming agent is determined in consideration of the type of foaming agent, the apparent density required for the foamed sheet, and the like, and is preferably 1.0 to 7.0 parts by mass with respect to 100 parts by mass of the resin, for example.

The mixture is supplied from the first extruding unit 11 to the second extruding unit 12 via the pipe 16, further mixed, cooled to an arbitrary temperature, and then guided to the resin flow path in the circular die 20.
The mixture guided to the resin flow path is extruded from the circular die 20, and the foaming agent is foamed to form the cylindrical foamed sheet 2a.
The cylindrical foamed sheet 2a is guided to the mandrel 30 while the cooling air blown from the cooling blower is blown. The cylindrical foamed sheet 2 a passes through the outer surface of the mandrel 30, is cooled to an arbitrary temperature, and is cut into two sheets by the cutter 32 to become the foamed sheet 2. The foam sheet 2 is wound around a guide roll 42 and a guide roll 44, respectively, and is taken up by a winder 40 to become a foam sheet roll 4.

In addition, although the above-mentioned embodiment demonstrated the foam sheet provided only with the foam layer which foamed the resin containing (A)-(B) component, this invention is not limited to these, One side of a foam layer or Non-foamed layers may be formed on both sides. Since the non-foamed layer is formed on the surface of the foamed layer, the strength can be further improved, printing on the surface of the non-foamed layer is facilitated, and the design can be improved.
Examples of the method for forming the non-foamed layer include a method in which a foamed layer similar to the foamed sheet is obtained by the above-described manufacturing method, and a non-foamed layer is formed on this surface by the T-die method.
As resin which comprises a non-foaming layer, (A) component, such as high impact polystyrene, or the resin containing (A) component and (B) component, etc. are mentioned, for example, (A) component is especially preferable. By forming the non-foamed layer composed of the component (A), the odor derived from the component (B) can be reduced.
The resin forming the non-foamed layer may be the same as or different from the resin forming the non-foamed layer.

(Molded body)
The molded body of the present invention is formed by molding the above-described foamed sheet of the present invention.
Examples of the molded body include trays having a shape in a plan view of a perfect circle, an ellipse, a semicircle, a polygon, a fan, and the like, a bowl-shaped container, a container having a bottomed cylindrical shape or a bottomed rectangular tube shape, and a natto container. Various containers such as a container with a lid, etc., or a lid attached to the container main body.
As the use of these containers, for example, food use is preferable.

The thickness of the molded body is determined in consideration of applications and the like, and is preferably 500 to 5000 μm, and more preferably 1500 to 4500 μm, for example.
The overall density of the molded body is determined in consideration of the use and the like, and is the same as the overall density of the foam sheet.
The surface layer density of the molded body is determined in consideration of the use and the like, and is the same as the overall density of the foam sheet.
The surface layer density ratio in the molded body is the same as the surface layer density ratio in the foamed sheet.
A molded object is manufactured by a conventionally well-known manufacturing method, for example, the thermoforming method etc. which pinch | interpose and shape | mold between a female type | mold and a male type | mold are mentioned, heating a foaming sheet at arbitrary temperature.

As described above, according to the foamed sheet of the present invention, since the resin containing the component (A) and the specific amount of the component (B) is foamed, excellent heat resistance can be exhibited.
In addition, since the rubber component is contained in a specific amount with respect to the component (B), the impact resistance can be enhanced while maintaining the heat resistance.
Furthermore, since the molded article of the present invention is formed by molding the foamed sheet of the present invention, the impact resistance can be enhanced while maintaining the heat resistance.

(Examples 1-8, Comparative Examples 1-4)
Using a manufacturing apparatus similar to the foam sheet manufacturing apparatus of FIG. 1, a foam sheet was obtained as follows.
According to the composition of Table 1, polystyrene resin (PS) (trade name: HP-555, rubber content: 0% by mass, manufactured by DIC), a mixture of polyphenylene ether resin (PPE) and PS (trade name: Noryl EFN4230, PPE) / PS = 70/30 (mass ratio), rubber content: 0% by mass, manufactured by Savic), and impact-resistant polystyrene resin (trade name: E640N, rubber content: 6% by mass, manufactured by Toyo Styrene Co., Ltd.) The mixed resin and a foam nucleating agent (trade name: DSM1401A, manufactured by Toyo Styrene Co., Ltd.) were mixed.
The above-mentioned mixture of raw materials was supplied from a hopper to the first mixing section (screw diameter: 115 mm), heated at a maximum temperature of 300 ° C., melted and kneaded to obtain a resin melt.
A foaming agent (a mixture of isobutane: normal butane = 70: 30 (mass ratio)) was supplied to the first extrusion part, and the resin melt and the foaming agent were mixed to obtain a mixture. The blending amount of the foaming agent was part by mass shown in Table 1 with respect to 100 parts by mass of the resin.
The mixture was supplied from the first mixing part to the second mixing part (screw diameter: 180 mm), cooled to 175 ° C., extruded with a circular die (160 mm diameter), and foamed to obtain a cylindrical foamed sheet. At this time, immediately after being extruded from the circular die, cooling air (30 ° C.) was blown onto the inner and outer surfaces of the cylindrical foamed sheet to cool it. The amount of cooling air blown (air volume) was as shown in Table 1.
The cooled cylindrical foam sheet was cut along the extrusion direction to obtain a foam sheet.
About the obtained foam sheet, thickness, basis weight, overall density, surface density of the inner surface (described as the first surface in the table) in the cylindrical shape, surface layer density of the outer surface (described as the second surface in the table) in the cylindrical shape The impact resistance, midpoint glass transition temperature (Tmg), moldability, container buckling strength and container brittleness were evaluated and the results are shown in Table 1.
In addition, the raw material whose compounding quantity is not described in the table | surface is not mix | blended.

(Comparative Example 5)
Foaming in the same manner as in Example 1 except that the amount of Noryl EFN4230 (trade name, manufactured by Savic) was 80 parts by mass and the amount of HP-555 (trade name, manufactured by DIC) was 10 parts by mass. An attempt was made to produce a sheet.
However, in this example, the pressure of the extruder increased and the load became too high, and a foam sheet could not be obtained.

(Evaluation method)
<Method for measuring rubber content in resin>
The rubber content in the raw material was determined by the following measurement method.
A sample 0.1 to 0.5 mg was precisely weighed and wrapped with a ferromagnetic metal body having a Curie point of 590 ° C. (Pyrofoil: manufactured by Nihon Analytical Industries, Ltd.). The sample wrapped with pyrofoil was disassembled with a Curie Point pyrolyzer JPS-700 type (manufactured by Nippon Analytical Industries, Ltd.). The butadiene monomer and 4-vinylcyclohexane produced from the decomposed sample were measured with a gas chromatograph GC7820 (manufactured by Agilent Technologies, detector: FID). The total amount of butadiene was calculated from the total peak area obtained and the absolute calibration curve prepared in advance, and this was used as the rubber content.
The measurement conditions are as follows.

≪Measurement conditions≫
・ Heating (590 ℃ -5sec)
・ Oven temperature (300 ℃)
・ Needle temperature (300 ℃)
Column (Inter Cap 5 (φ0.25 mm × 30 m (film thickness 0.25 μm): GL Sciences Inc.)
・ Temperature condition (After holding at 50 ° C. for 0.5 minutes, the temperature is raised to 200 ° C. at 10 ° C./minute, then raised to 320 ° C. at 20 ° C./minute and held at 320 ° C. for 0.5 minutes)
・ Carrier gas (He)
・ He flow (25ml / min)
・ Inlet pressure (100 KPa)
・ Inlet temperature (300 ℃)
・ Detector temperature (300 ℃)
・ Split ratio (1/30)
A standard sample for preparing a calibration curve is POLYSCIENCES. INC / St / BD = 85/15 (CAT # 07073) resin was used.

<Thickness>
Arbitrary 21 positions in the width direction of the foamed sheet (direction perpendicular to the traveling direction during production) were used as measurement points. This measurement point was measured in 0.01 mm units with a thickness measuring instrument (manufactured by Teclock Co., Ltd., model: SM-125). The arithmetic average of the measured values was taken as the thickness of the foam sheet in each example.

<Basis weight>
Except 20 mm in the width direction at both ends of the foamed sheet, 10 sections of 10 cm × 10 cm were cut out at equal intervals in the width direction, and the mass (g) of each section was measured to 0.001 g unit. The value obtained by converting the average value of the mass (g) of each section into the mass per 1 m ² was defined as the basis weight (g / m ² ).

<Overall density>
A 50 cm ³ foam sheet was cut out as a test piece so as not to change the cell structure, the mass and volume of the test piece were measured, and the overall density was calculated by the following equation (1). However, the test piece was cut out from a foamed sheet that had passed 72 hours or more after production (maximum 90 days), and was allowed to stand for 24 hours in an atmospheric condition of 23 ° C. ± 2 ° C. and 50 RH% ± 5 RH%.

Total density (g / cm ³ ) = mass of test piece (g) ÷ volume of test piece (cm ³ ) (1)

<Surface density>
With a slicer (Fortuna (Germany) made splitting machine, model AB-320-D), the foamed sheet was sliced to a thickness of 200 μm from the surface, and this was cut into a width of 25 mm and a length of 150 mm to obtain a surface layer. . The mass and volume of the obtained surface layer were measured, and the surface layer density was calculated from the following formula (2). However, the surface layer was cut out from a foamed sheet that had passed 72 hours or more after production (maximum 90 days), and was left under atmospheric conditions of 23 ° C. ± 2 ° C. and 50 RH% ± 5 RH% for 24 hours.

Surface layer density (g / cm ³ ) = surface layer mass (g) ÷ surface layer volume (cm ³ ) (2)

(Impact resistance)
A test piece having a length of 150 mm and a width of 50 mm was cut out from the foamed sheet. As the test piece, the length direction of the foam sheet (the progress direction during production) is the length direction of the test piece (first test piece), and the width direction of the foam sheet is the length direction of the test piece. One (second test piece) was cut out. The first test piece is cut out from at least three points in the length direction of the foamed sheet, and the second test piece is cut out from at least three points in the width direction of the foamed sheet.
The test piece was positioned at a height of 50 mm from the floor, one surface of the test piece was directed vertically upward, and a position of 25 mm from both ends in the length direction of the test piece was clamped with a pressure of 2 MPa. The distance between the clamps was 100 mm.
A spherical weight (made of steel, diameter 27 mm, mass 80 g) was dropped onto the center of the test piece. The height at which the spherical weight was dropped for the first time (falling height) was 5 cm above the test piece (dropping operation). When the first test piece and the second test piece are subjected to a dropping operation, and the number of damaged test pieces is less than or equal to 2 in the first and second test pieces, The falling height of the spherical weight was increased by 5 cm, and the second dropping operation was performed. This drop operation is performed up to a drop height of 100 cm, and in the first and second test pieces, the maximum value of the drop height where the number of damaged test pieces is 2 or less is used as an impact resistance index. did.
However, the test piece was cut out from a foamed sheet after 72 hours or more (90 days at the maximum) after molding, and left in an atmospheric condition of 23 ° C. ± 2 ° C. and 50 RH% ± 5 RH% for 24 hours.

<Intermediate glass transition temperature (Tmg)>
A sample of 6.5 ± 0.5 mg was taken from the foamed sheet and subjected to differential scanning calorimetry based on JIS K7121 (device used: differential scanning calorimeter device manufactured by SII Nanotechnology, model name: DSC6220) ). In this test, the “midpoint glass transition temperature (Tmg)” described in JIS K7121 9.3 (1) was observed.
As a result of this measurement, a sample having a Tmg of 110 ° C. or higher was evaluated as “good heat resistance”, and a sample having a Tmg of less than 110 ° C. was determined as “poor heat resistance”.

<Moldability>
The foam sheet was molded with a single molding machine (FM-6AS: manufactured by Tosei Sangyo Co., Ltd.). The shape of the mold is such that the diameter of the opening is 14.4 cm, the diameter of the bottom is 11.8 cm, and the height is 6.0 cm. If the reproducibility of the shape of the mold is good, the inner diameter of the opening is 14.0 cm (the outer diameter is 14.4 cm, the outer diameter including the flange is about 15.5 cm), and the bottom inner diameter is 11.4 cm (outer A bowl-shaped container having a circular shape in a plan view and having a diameter of 11.8 cm) and a height of 6.2 cm was obtained. The molding conditions were an oven atmosphere temperature of 160 ° C. and a heating time of 13 to 15 seconds.
From the state of the obtained container, it evaluated according to the following evaluation criteria.

≪Evaluation criteria≫
○ (Good): Good reproducibility of the shape of the mold, and a good molded product can be obtained.
Δ (slightly good): No defect occurs, but the reproducibility of the shape of the mold is somewhat poor.
X (defect): A hole or a crack occurs in the molded product, and a good molded product cannot be obtained.

<Container buckling strength>
About the container obtained by carrying out similarly to evaluation of a moldability, the buckling strength was measured using the tensilon universal testing machine (model number: UCT-10T, orientec company make). When measuring the buckling strength, the Tensilon universal testing machine was equipped with an upper mounting jig provided with a rectangular groove and a lower mounting jig provided with an arc-shaped groove. .
Insert the upper part of the flange part formed on the periphery of the container into the rectangular groove of the upper mounting jig, insert the lower part of the flange part into the arc-shaped groove of the lower mounting jig, and It was supported between the upper and lower mounting jigs. The maximum load up to the yield point was measured by compressing the supported container at a speed of 100 mm / min. The maximum load of each container was measured by compressing to a maximum of 50 mm. About 30 containers of each example, the maximum load was measured and the average value was made into container buckling strength.

<Vessel brittleness>
About 30 containers obtained in the same manner as the evaluation of moldability, a compressive load was applied to the flange portion of the container using a Tensilon universal testing machine (model number: UCT-10T, manufactured by Orientec Co., Ltd.). In evaluating the brittleness of the container, a compression jig was attached to a Tensilon universal testing machine. This compression jig has a plate shape of width 10 mm × length 300 mm × height 50 mm, and has a curved surface (R: 10 mm) that bulges toward the center in the width direction on the tip surface. A compression jig was brought into contact with the flange portion of the container, and compression was performed with this compression jig until the compression distance became 10 mm. The state at the time when the compression distance became 10 mm was visually observed, and the results were classified and evaluated according to the following evaluation criteria.

≪Evaluation criteria≫
○ (good): 10 or less cracks occurred.
Δ (slightly good): The number of cracks exceeds 10 and less than 20.
X (defect): 20 or more cracks occurred.

As shown in Table 1, in Examples 1 to 8 to which the present invention was applied, Tmg was 110 ° C. or higher and excellent in heat resistance. In addition, Examples 1-8 had an impact resistance evaluation of 75 cm or more.
Furthermore, in Examples 1 to 8, the moldability was “Δ” to “◯”, the container buckling strength was 3.5 N or more, and 12 or less were cracked in the evaluation of container brittleness.
On the other hand, Comparative Example 1 containing no rubber component and Comparative Example 2 having a rubber content of 0.6 parts by mass with respect to 100 mass of PPE produced a crack in the evaluation of the brittleness of the foamed sheet with an impact resistance evaluation of 50 cm. The number was 20 or more (evaluation “×”).
In Comparative Examples 3 and 4 in which the rubber content relative to 100 masses of PPE is more than 10.0 mass parts, Tmg was less than 110 ° C.
From these results, it was found that application of the present invention can achieve both heat resistance and impact resistance.

  2, 2a Foam sheet

Claims (3)

Foamed resin containing polystyrene resin and polyphenylene ether resin,
Containing 10-50 parts by mass of the polyphenylene ether resin with respect to 100 parts by mass of the resin;
The rubber content is 1.4 to 8.6 parts by mass with respect to 100 parts by mass of the polyphenylene ether resin,
The thickness is 500 μm or more,
A density ratio represented by [density at a thickness of 200 μm from the surface] / [total density] is a resin foam sheet having a density of 1.5 to 2.5 . The resin foam sheet according to claim 1, wherein the overall density is 0.05 to 0.25 g / cm ³ . The molded object formed by shape | molding the resin foam sheet of Claim 1 or 2 .

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