JP2019183096A - Thermoplastic resin foam sheet and molded body - Google Patents

Abstract

To enhance productivity and suppress generation of poor appearance in a thermoplastic resin foam sheet.SOLUTION: A thermoplastic resin foam sheet has a foam layer, the foam layer contains a thermoplastic resin and a group of inorganic particles, the group of the inorganic particles contains a group of first inorganic particles, average specific surface area of the group of the first inorganic particle is 1.0 m/g or more and less than 200 m/g. Content of the first inorganic particle is preferably 10 to 100 pts.mass based on 100 pts.mass of the group of the inorganic particles, and bulk density of the group of the first inorganic particles is preferably 0.02 to 1.0 g/cm.SELECTED DRAWING: Figure 1

Description

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

A foamed sheet (thermoplastic resin foamed sheet) obtained by foaming a thermoplastic resin such as polystyrene resin is widely used as a raw material for containers for storing foods and the like. The molded article of the thermoplastic resin foam sheet has characteristics that it is lightweight, has high heat insulation properties, has high strength and is difficult to break.
The molded article of the thermoplastic resin foam sheet has various demands such as further improvement in heat resistance, improvement in weather resistance, diversification of hue, reduction in odor, and the like. In the thermoplastic resin foam sheet, it is necessary to improve moldability and the like while meeting the above-mentioned demand. In order to satisfy these demands, there is a technique for blending inorganic particles into a thermoplastic resin foam sheet. However, when a thermoplastic resin foam sheet blended with inorganic particles is produced, there is a problem that productivity is easily lost.

For example, a container molded from a polystyrene resin foam sheet is not sufficiently high in heat resistance. For this reason, the container shape | molded from the foam sheet made from a general purpose polystyrene resin tends to deform | transform when heated by a microwave oven etc. For this problem, there is a thermoplastic resin foam sheet containing a polyphenylene ether-based resin.
The thermoplastic resin foam sheet emits a unique odor depending on the type of resin. In order to suppress this odor, a thermoplastic resin foam sheet containing a deodorant such as silica particles has been proposed. However, when inorganic particles of a deodorant are blended in the thermoplastic resin foam sheet, the thermoplastic resin foam sheet manufacturing equipment is clogged, and the productivity tends to be impaired. In addition, even if the production equipment does not become clogged, if the aggregate of inorganic particles adheres to the opening of the die, scratches such as ridges may be formed on the surface of the resulting foam sheet. For such problems, Patent Document 1 discloses a polystyrene-based resin composition containing a calcined hydrotalcite, a silica-based deodorant, a fatty acid metal salt, a glycerin fatty acid ester, and a polystyrene-based resin in a specific ratio. Things have been proposed.

Japanese Patent Application Laid-Open No. 2015-0667705

However, the conventional technology cannot sufficiently prevent clogging of manufacturing equipment due to inorganic particles. In addition, the conventional technology cannot sufficiently prevent the appearance defect of the thermoplastic resin foam sheet.
Therefore, the present invention has an object of a thermoplastic resin foam sheet that enhances productivity and hardly causes poor appearance.

[1] having a foam layer;
The foam layer contains a thermoplastic resin and a group of inorganic particles,
The group of inorganic particles comprises a group of first inorganic particles;
The average specific surface area of the group of the first inorganic particles, 1.0 m ² / g or more 200m less than ² / g, the thermoplastic resin foam sheet.
[2] The thermoplastic resin foam sheet according to [1], wherein the content of the first inorganic particles is 10 to 100 parts by mass with respect to 100 parts by mass of the group of inorganic particles.
[3] The thermoplastic resin foam sheet according to [1] or [2], wherein the bulk density of the group of the first inorganic particles is 0.02 to 1.0 g / cm ³ .
[4] The primary particles of the group of the first inorganic particles according to any one of [1] to [3], wherein a ratio represented by a mode diameter / median diameter is 0.1 or more and less than 1.0. Thermoplastic resin foam sheet.
[5] The thermoplastic resin foam sheet according to any one of [1] to [4], wherein the standard deviation of the median diameter of the primary particles of the group of the first inorganic particles is 0.3 μm or more.
[6] The thermoplastic resin foam sheet according to any one of [1] to [5], wherein the thermoplastic resin includes a polystyrene resin or includes a polystyrene resin and a polyphenylene ether resin.
[7] The thermoplastic resin contains a polyphenylene ether resin,
Content of the said polyphenylene ether-type resin is a thermoplastic resin foam sheet in any one of [1]-[6] which is 10-50 mass parts with respect to 100 mass parts of said thermoplastic resins.
[8] The group of inorganic particles includes any one of [1] to [7], including at least one selected from a bubble regulator, a stabilizer, an ultraviolet absorber, an antioxidant, a colorant, and a deodorant. The thermoplastic resin foam sheet according to claim 1.
[9] The heat according to any one of [1] to [8], wherein the content of the group of the first inorganic particles is 0.05 to 20 parts by mass with respect to 100 parts by mass of the thermoplastic resin. Plastic resin foam sheet.

[10] A molded article obtained by molding the thermoplastic resin foam sheet according to any one of [1] to [9].
[11] The molded article according to [10], which is a container for food.

Moreover, this invention has the following aspects.
[12] The group of the first inorganic particles includes a particle group of a fired hydrotalcite,
Content of the particle group of the said hydrotalcite baked material is a thermoplastic resin foam sheet as described in [1] which is 40-100 mass parts with respect to 100 mass parts of total amounts of a group of said 1st inorganic particle.
[13] The group of the first inorganic particles includes a particle group of the fired hydrotalcite and a particle group of silica,
The thermoplastic resin foam sheet according to [12], wherein the mass ratio represented by [particle group of calcined hydrotalcite] / [particle group of silica] is 4/6 to 9/1.
[14] The thermoplastic resin foam according to [12] or [13], wherein the content of the first inorganic particle group is 10 to 100 parts by mass with respect to 100 parts by mass of the inorganic particle group. Sheet.
[15] The thermoplastic resin foam sheet according to any one of [12] to [14], wherein a bulk density of the particle group of the hydrotalcite fired product is 0.02 to 1.0 g / cm ³ .
[16] The primary particle of the particle group of the fired hydrotalcite has a ratio represented by a mode diameter / median diameter of 0.1 or more and less than 1.0, and any one of [12] to [15] The thermoplastic resin foam sheet as described.
[17] The thermoplastic resin foam sheet according to any one of [12] to [16], wherein a median diameter of primary particles of the particle group of the hydrotalcite fired product is 0.05 to 30 μm.
[18] The thermoplastic resin foam sheet according to any one of [12] to [17], wherein a standard deviation of median diameter of primary particles of the particle group of the hydrotalcite fired product is 0.3 μm or more.

  According to the thermoplastic resin foam sheet of the present invention, productivity is increased and appearance defects are less likely to occur.

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

(Thermoplastic resin foam sheet)
The thermoplastic resin foam sheet of the present invention (hereinafter sometimes simply referred to as “foam sheet”) has a foam layer containing a thermoplastic resin and a group of inorganic particles.
The foam sheet may have a single-layer structure composed of only a foam layer, or may have a multilayer structure including a non-foam layer on one or both sides of the foam layer.

  The thickness of the foam sheet can be determined in consideration of the application, and is preferably 500 to 4000 μm, and more preferably 1000 to 2500 μm, for example.

[Foamed layer]
The foam layer is a layer formed by foaming a resin composition containing a resin and a group of inorganic particles. The resin contains a thermoplastic resin. A foam sheet exhibits heat insulation by having a foam layer.

  The thermoplastic resin is, for example, a polystyrene resin (hereinafter sometimes referred to as component (A)), a polyphenylene ether resin (hereinafter sometimes referred to as component (B)), a polyolefin resin, or the like.

Component (A) is, for example, a homopolymer of a styrene monomer such as styrene, α-methylstyrene, vinyltoluene, chlorostyrene, ethylstyrene, i-propylstyrene, dimethylstyrene, bromostyrene, or a copolymer thereof; Copolymer of styrene monomer as the main component (50% by mass or more), styrene monomer and vinyl monomer polymerizable therewith: copolymer of styrene monomer and rubber such as butadiene, styrene monomer So-called high impact polystyrene, which is a polymer or a mixture of a copolymer of styrene monomer and vinyl monomer and a diene rubber-like polymer.
Examples of vinyl monomers that can be polymerized with styrene monomers include alkyl (meth) acrylates such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, and cetyl (meth) acrylate, (meth) acrylonitrile, and dimethyl. And bifunctional monomers such as maleate, dimethyl fumarate, diethyl fumarate, ethyl fumarate, divinylbenzene, and alkylene glycol dimethacrylate. These vinyl monomers may be used alone or in combination of two or more.
Examples of the diene rubbery 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 alone or in combination of two or more.

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 may be a polystyrene resin that is a recycled material. .
The recycled material is a used polystyrene-based resin foam molding. Recycled raw materials are those obtained by collecting fish boxes, household appliance cushioning materials, food packaging trays, etc., and regenerating them using the limonene dissolution method or heating volume reduction method. Recyclable raw materials that can be used are non-foamed polystyrene resin moldings that are separated and collected from household appliances (eg, televisions, refrigerators, washing machines, air conditioners, etc.) and office equipment (eg, copiers, facsimiles, printers, etc.). The body may be pulverized, melt kneaded and re-pelletized.

  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, with respect to 100 parts by weight of the thermoplastic resin (resin constituting the foamed layer), and 70 to 90. Part by mass is more preferable. If content of (A) component is more than the said lower limit, a foam sheet will become hard and handling of a molded object will become easier. If content of (A) component is below the said upper limit, when other resin is mix | blended, it will be easy to exhibit the characteristic of other resin.

  A foaming layer exhibits the outstanding heat resistance by containing polyphenylene ether-type resin ((B) component).

  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.

  The content of the component (B) in the foam layer is preferably 10 to 50 parts by mass, more preferably 10 to 40 parts by mass, and still more preferably 10 to 30 parts by mass with respect to 100 parts by mass of the thermoplastic resin. If content of (B) component is more than the said lower limit, the heat resistance of a foam sheet will increase more. If content of (B) component is below the said upper limit, a foamed sheet will become hard and handling of a molded object will become easier.

  The polyolefin resin (hereinafter also referred to as the component (C)) is, for example, a homopolymer of an olefin monomer such as ethylene or propylene or a copolymer thereof, an olefin monomer as a main component, and an olefin monomer. Examples thereof include a copolymer with a polymerizable vinyl monomer.

  The content of the component (C) in the foamed layer is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, and may be 0 parts by mass with respect to 100 parts by mass of the thermoplastic resin. If content of (C) component is below the said upper limit, a foamed sheet will become hard and handling of a molded object will become easier.

These thermoplastic resins may be used alone or in combination of two or more.
Especially, it is preferable that a thermoplastic resin contains a polystyrene-type resin or a polyphenylene ether-type resin, or contains a polystyrene-type resin and a polyphenylene-type resin. Among these, the thermoplastic resin preferably includes a polystyrene resin, or preferably includes a polystyrene resin and a polyphenylene ether resin, and more preferably includes a polystyrene resin and a polyphenylene ether resin.

  The thermoplastic resin may contain a rubber component. A foaming layer is excellent in impact resistance by containing a rubber component. In addition, it is easy to prevent breakage during the production of the foam layer or foam sheet or the production of the molded body.

The rubber component in the foamed layer 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 layer is determined in consideration of the content of the component (B), and is preferably 0.2 to 2.0 parts by weight, for example, with respect to 100 parts by weight of the thermoplastic resin. 3-1.8 mass parts is more preferable. When the rubber content is equal to or higher than the lower limit, the impact resistance is further increased. If the rubber content is not more than the above upper limit value, the foamed layer has an appropriate hardness, and the strength of the molded product obtained by molding is further increased.

  In the thermoplastic resin, the rubber content relative to 100 parts by mass of the component (B) is preferably 1.0 to 10.0 parts by mass, more preferably 1.5 to 8.0 parts by mass, and 2.0 to 6 0.0 part by mass is more preferable. If the rubber content is not less than the above lower limit, the impact resistance of the foamed sheet can be further improved, and it is more difficult to break during production. If the rubber content is less than or equal to the above upper limit, the heat resistance of the foamed sheet is further increased.

  The foam layer contains a group of inorganic particles. A foaming layer exhibits the effect derived from an inorganic particle by containing the group of inorganic particles.

  The group of inorganic particles is, for example, at least one selected from a bubble regulator, a stabilizer, an ultraviolet absorber, an antioxidant, a colorant, and a deodorant. The group of inorganic particles is preferably a bubble regulator or deodorant.

  Examples of the air conditioner include a mixture of inorganic powders such as talc and silica. These bubble regulators increase the closed cell ratio of the foam layer and easily form the foam layer.

  The stabilizer is, for example, a calcium zinc-based heat stabilizer, a tin-based heat stabilizer, a lead-based heat stabilizer, or the like.

  Examples of the ultraviolet absorber include a cesium oxide ultraviolet absorber and a titanium oxide ultraviolet absorber.

  Examples of the antioxidant include cerium oxide, cerium oxide / zirconia solid solution, cerium hydroxide, carbon, carbon nanotube, titanium oxide, and fullerene.

Examples of the colorant include titanium oxide, carbon black, titanium yellow, iron oxide, ultramarine blue, cobalt blue, calcined pigment, metallic pigment, mica, pearl pigment, zinc white, precipitated silica, cadmium red, and the like.
These colorants may be used alone or in combination of two or more. When the foamed sheet of the present invention is used for a food container, it is preferable to select a product registered by the Sanitation Council for polyolefins from the above colorants.

  Examples of the deodorant include silica, zeolite, zirconium phosphate, and calcined hydrotalcite.

The group of inorganic particles includes the first group of inorganic particles.
The group of first inorganic particles is a group of inorganic particles having an average specific surface area of 1.0 m ² / g or more and less than 200 m ² / g.
The foam layer is manufactured by an extrusion method as in the manufacturing method described later. In this extrusion manufacturing method, when the inorganic particles are aggregated into large secondary particles, the secondary particles are likely to be clogged by a die of an extrusion molding machine. In addition, when large secondary particles adhere to the inside of the flow path (for example, the opening portion of the die) or the like, the attached secondary particles form streaks on the surface of the foam layer.
Since the first group of inorganic particles hardly aggregates in the resin composition, clogging of manufacturing equipment is difficult to occur when the foamed layer is manufactured. In addition, since the first group of inorganic particles is difficult to aggregate, even if it adheres to a die or the like, it is difficult to form streaks that impair the appearance of the foam sheet.
Furthermore, by blending the first inorganic particle group into the resin composition, the second inorganic particles can be hardly aggregated even when the second inorganic particle group described later is blended into the resin composition.

Average specific surface area of the group of first inorganic particles is preferably 10 to 150 m ² / g, more preferably from 30 to 150 m ² / g, more preferably ^{40~150m 2 / g, 100~150m 2 /} g especially Preferably, 100 to 130 m ² / g is most preferable. When the average specific surface area is within the above range, the particles can be more preferably prevented from aggregating. In addition, if the average specific surface area is within the above range, enlargement of the particle diameter of the secondary particles of the inorganic particles can be suppressed more favorably.
The average specific surface area is an average value of the BET specific surface areas of 100 samples measured by the BET method.

The bulk density of the first inorganic particles is preferably 0.02~1.0g / cm ^3, more preferably 0.05~0.8g / cm ^3, more preferably 0.1~0.7g / cm ³ . If a bulk density is more than the said lower limit, mixing efficiency with a resin composition will increase and handling will become easier. If a bulk density is below the said upper limit, a density difference with a resin composition will become small and will become easy to disperse | distribute. The bulk density is measured by the following measuring method.
<Measurement method>
A sample is filled in a metal container having a volume of 25 cm ³ having an opening at the upper end. At this time, the sample is filled into the metal container for 2 to 3 minutes using a quantitative feeder or the like. Scrape the sample rising from the opening of the metal container. The mass of the sample in the metal container is measured, and this is divided by the volume (25 cm ³ ) to obtain the bulk density.

The median diameter of the primary particles of the group of the first inorganic particles (hereinafter sometimes referred to as “primary median diameter”) is preferably 0.05 to 30 μm, more preferably 0.1 to 20 μm, and 0.15 to 10 μm. Is more preferable, 2 to 6 μm is particularly preferable, and 3 to 5 μm is most preferable. If a primary median diameter is more than the said lower limit, generation | occurrence | production of a secondary particle can be suppressed more favorably and the enlargement of the particle diameter of the produced secondary particle can be suppressed more favorably. If the primary median diameter is less than or equal to the above upper limit, clogging of the die or the like is less likely to occur.
The primary median diameter is a volume average particle diameter (50 mass% particle diameter) determined by a laser diffraction method.

The distribution of the primary median diameter is preferably broad. The reason is not clear, but if the distribution of the primary median diameter is broad, the inorganic particles are more difficult to aggregate.
Therefore, the standard deviation of the primary median diameter is preferably 0.3 μm or more, more preferably 0.3 to 0.7 μm, further preferably 0.4 to 0.6 μm, and particularly preferably 0.45 to 0.55 μm.

The mode diameter of the primary particles of the first inorganic particle group (hereinafter sometimes referred to as “primary mode diameter”) is preferably 0.5 to 10 μm, more preferably 0.8 to 7 μm, and 0.9 to 4 Is more preferable, and 1-2 μm is particularly preferable.
The primary mode diameter is a re-frequency value (volume distribution) obtained by a laser diffraction method.
The primary median diameter and the primary mode diameter are measured by the following method. The measurement object is dispersed in 0.2% by mass of sodium hexametaphosphate solvent. The primary particle diameter of this dispersion is measured with a laser diffraction type distribution measuring device (SALD-2200, manufactured by Shimadzu Corporation) to obtain a primary median diameter and a primary mode diameter.

  The ratio represented by [primary mode diameter] / [primary median diameter] in the group of first inorganic particles (hereinafter sometimes referred to as “Mo / Me ratio”) is preferably 0.1 or more and less than 1.0. 0.1 to 0.6 is more preferable, and 0.2 to 0.5 is more preferable. If the Mo / Me ratio is equal to or higher than the lower limit, clogging of the die or the like is less likely to occur. If the Mo / Me ratio is less than or equal to the above upper limit, the generation of secondary particles is further suppressed, and clogging of dies and the like is less likely to occur.

The group of the first inorganic particles is preferably at least one selected from a bubble regulator, a stabilizer, an ultraviolet absorber, an antioxidant, a colorant and a deodorant.
Examples of the material of the first inorganic particle group include calcined hydrotalcite and silica. Among them, the material of the first inorganic particle group is preferably a hydrotalcite fired product or silica, and more preferably a hydrotalcite fired product. If it is a fired hydrotalcite, even if it is the group of the 1st inorganic particle, sufficient deodorizing effect can be exhibited.
The group of the first inorganic particles may be a single type or a combination of two or more types. From the viewpoint of complementing different functions, the group of the first inorganic particles is preferably a combination of two or more, and more preferably a combination of the calcined hydrotalcite and silica.

Hydrotalcite is a kind of naturally occurring clay mineral. In general, hydrotalcite is a double hydroxide represented by the following formula (11).
M ¹ _8-x M ² _x (OH) ₁₆ CO ₂ .nH ₂ O (11)
(11) In the formula, M ¹ is any ^one of Mg ²⁺ , Fe ²⁺ , Zn ²⁺ , Ca ²⁺ , Li ²⁺ , Ni ²⁺ , Co ²⁺ , and Cu ²⁺ . M ² is any one of Al ³⁺ , Fe ³⁺ , and Mn ²⁺ . x is preferably 2 to 5. n is an integer of 0 or more.

The hydrotalcite may be a synthetic product. The synthetic product of hydrotalcite is obtained by the following manufacturing method, for example.
An aqueous suspension of basic magnesium carbonate particles and an aqueous suspension of aluminum hydroxide are mixed to form a mixed suspension. At this time, the ratio of magnesium atoms to aluminum atoms (Mg / Al) is set to a predetermined ratio (for example, 2.6 to 3.2). Caustic is added to the mixed suspension to obtain a reaction solution having a pH of 8.5 to 11.5. The caustic alkali is sodium hydroxide, potassium hydroxide, ammonium hydroxide or the like. The obtained reaction liquid is aged by heating at 50 to 100 ° C. for 0.5 to 20 hours, for example. Next, the hydrotalcite particles are solid-liquid separated from the mixed suspension. The separated hydrotalcite particles are washed, dehydrated and dried to obtain a synthesized hydrotalcite.
Synthetic baked products can be used in the same manner as natural baked products.
Hydrotalcite releases adsorbed water and crystal water when heated. Hydrotalcite releases adsorbed water when baked to 200 ° C. or higher, and carbonate groups and hydroxyl groups are eliminated when baked to 400 ° C. or higher (for example, 550 ° C.).

The fired hydrotalcite is obtained by firing hydrotalcite at the above temperature. As the hydrotalcite fired product, for example, a compound represented by the following formula (12) is preferable.
Mg _0.7 Al _0.3 O _1.15 (12)

  The content of the first inorganic particles in the foamed layer is preferably 10 to 100 parts by weight, more preferably 20 to 100 parts by weight, and more preferably 40 to 100 parts by weight with respect to 100 parts by weight as the total amount of the inorganic particles. Part is more preferable, 50 to 100 parts by weight is particularly preferable, and 60 to 100 parts by weight is most preferable. If the content of the group of the first inorganic particles is not less than the above lower limit value, clogging of a die or the like can be prevented more favorably, and the appearance of the foamed sheet can be made better.

  The total amount of the first inorganic particles in the foamed layer is preferably 0.05 to 20 parts by mass, more preferably 0.1 to 10 parts by mass, and more preferably 0.3 to 100 parts by mass with respect to 100 parts by mass of the thermoplastic resin. 5.0 parts by mass is more preferable. When the total amount of the first inorganic particle group is equal to or more than the lower limit, aggregation of the inorganic particle group can be more effectively suppressed. If the total amount of the first group of inorganic particles is not more than the above upper limit, clogging of the die or the like can be prevented more favorably, and the appearance of the foamed sheet can be made better.

  When the group of the first inorganic particles contains a cell regulator, the content of the cell regulator in the foam layer is preferably 0.01 to 5.0 parts by mass with respect to 100 parts by mass of the thermoplastic resin. 0.02-3.0 mass parts is more preferable, and 0.03-2.0 mass parts is still more preferable.

  When the first group of inorganic particles contains a bubble regulator and a deodorant, the total amount of the first inorganic particle group is 10 parts by mass with respect to 100 parts by mass of the total amount of the inorganic particle group. To 100 parts by mass, preferably 20 to 200 parts by mass, more preferably 30 to 100 parts by mass, further preferably 40 to 100 parts by mass, particularly preferably 50 to 100 parts by mass, and most preferably 60 to 100 parts by mass. preferable.

When the group of the first inorganic particles contains the particle group of the hydrotalcite fired product, the content of the particle group of the hydrotalcite fired product is based on 100 parts by mass of the total amount of the first inorganic particle group, 40-100 mass parts is preferable, 50-100 mass parts is more preferable, and 60-100 mass parts is further more preferable. If it is more than the said lower limit, the odor of a thermoplastic resin foam sheet can be suppressed more.
Moreover, when the group of 1st inorganic particles has both a hydrotalcite baked material and the group of other 1st inorganic particles, it is 40 with respect to 100 mass parts of total amounts of the group of 1st inorganic particles. -90 mass parts is preferable, 40-80 mass parts is preferable, 40-70 mass parts is preferable, and 50-70 mass parts is especially preferable.

When the group of the first inorganic particles contains the hydrotalcite fired product and silica, the content of the first inorganic particles is 10 to 100 parts by mass with respect to 100 parts by mass of the total amount of the group of inorganic particles. Preferably, 20 to 200 parts by mass is more preferable, 30 to 100 parts by mass is further preferable, 40 to 100 parts by mass is further preferable, 50 to 100 parts by mass is particularly preferable, and 60 to 100 parts by mass is most preferable.
When the first inorganic particle group includes the hydrotalcite fired particle group and the silica particle group, the mass ratio represented by [hydrotalcite fired particle group] / [silica particle group]. (Hereinafter sometimes referred to as “H / S ratio”) is preferably 4/6 to 9/1, more preferably 5/5 to 9/1, and even more preferably 5/5 to 7/3. If the H / S ratio is within the above range, the productivity can be further improved and the appearance defects can be further suppressed.

  When the first group of inorganic particles contains a hydrotalcite fired particle group, the hydrotalcite fired particle group has a primary median diameter, a primary mode diameter, the Mo / Me ratio, and the median diameter standard described above. It is preferable to satisfy at least one of the deviations.

The group of inorganic particles may contain a second group of inorganic particles. The second group of inorganic particles is a group of inorganic particles having an average specific surface area of 200 m ² / g or more.

The larger the average specific surface area of the second inorganic particle group, the better the function required for the second inorganic particle group.
The average specific surface area of the ^second group of inorganic particles is preferably 200 to 1000 m ² / g, more preferably 250 to 900 m ² / g, and further preferably 300 to 850 m ² / g.

  The average particle size of the second group of inorganic particles is preferably from 0.1 to 50 μm, more preferably from 0.3 to 40 μm, still more preferably from 0.5 to 30 μm. If the average particle size of the second inorganic particle group is equal to or greater than the lower limit, the function of the second inorganic particle group is more easily exhibited. If the average particle size of the second group of inorganic particles is not more than the above upper limit value, clogging of the die or the like can be prevented better, and the appearance of the foamed sheet can be made better.

  When the group of inorganic particles contains the group of second inorganic particles, the content of the group of second inorganic particles in the foamed layer is 10 to 80 masses with respect to 100 parts by mass of the total amount of inorganic particles. Part is preferable, 20-70 mass parts is more preferable, 30-60 mass parts is further more preferable, and 30-50 mass parts is especially preferable. If the content of the second inorganic particles is not less than the above lower limit value, the function of the group of the second inorganic particles is more easily exhibited. If the content of the second group of inorganic particles is not more than the above upper limit, clogging of the die or the like can be prevented more favorably, and the appearance of the foamed sheet can be made better.

The group of inorganic particles may contain a third group of inorganic particles having an average specific surface area of less than 10 m ² / g.

  0.05-20 mass parts is preferable with respect to 100 mass parts of thermoplastic resins, 0.1-10 mass parts is more preferable, and the total amount of the group of the inorganic particle in a foamed layer is 0.3-5.0. Part by mass is more preferable. If the total amount of the group of inorganic particles is equal to or more than the above lower limit value, the function of the group of inorganic particles can be exhibited better. If the total amount of the group of inorganic particles is not more than the above upper limit value, clogging of the die or the like can be prevented more favorably and the appearance of the foamed sheet can be made better.

  The foam layer can contain optional components such as foam nucleating agent, nucleating agent, deodorant, ultraviolet absorber, antioxidant, lubricant, flame retardant, antistatic agent and other additives.

  The type of the optional 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.

The thickness of the foam layer can be determined in consideration of the use of the foam sheet. For example, when the foamed sheet is used for a food container, the thickness of the foamed sheet is preferably 500 to 4000 μm, and more preferably 1000 to 2500 μm.
The thickness is a value obtained by the following method. The thickness of any 10 points in the TD direction of the foam layer is measured with a micro gauge. The measured values at 10 points are averaged to obtain the thickness of the foamed layer.

The density of the entire foam layer (total density) is, for example, preferably ^{0.05~0.25g / cm 3, 0.06~0.22g / cm} 3 is more preferable. If the overall density is equal to or higher than the lower limit, the strength of the foam layer can be further improved. If the overall density is not more than the above upper limit value, the heat insulating property of the foamed sheet can be further enhanced.

  The average cell diameter of the foam layer is preferably, for example, 80 to 450 μm. The average cell diameter of the foam layer is a value measured according to the method described in ASTM D2842-69.

  The closed cell ratio of the foam layer is preferably 70% or more, more preferably 80% or more, further preferably 90% or more, and may be 100%. The closed cell ratio of the foamed layer is a value measured by the method described in JIS K7138: 2006 “Rigid Foamed Plastics—How to Obtain Open Cell Ratio and Closed Cell Ratio”.

The foamed sheet may have a non-foamed layer on one side or both sides of the foamed layer.
Resin which comprises a non-foamed layer is not specifically limited, Resin similar to resin which comprises a foamed layer is mentioned.
The resin constituting the non-foamed layer may be the same as or different from the resin constituting the foamed layer.

  The thickness of the non-foamed layer is determined in consideration of the use of the foamed sheet and the like, for example, 50 to 300 μm is preferable, and 70 to 200 μm is more preferable. If the thickness of the foamed layer is not less than the above lower limit, the strength of the foamed sheet can be further improved. If the thickness of the non-foamed layer is not more than the above upper limit value, the foamed sheet can be reduced in weight.

(Production method)
The foam sheet is manufactured by a conventionally known manufacturing method.
The manufacturing method of a foam sheet is demonstrated taking the manufacturing method of a single layer foam sheet as an example.
1 is an apparatus for obtaining a foamed sheet by extrusion molding. The manufacturing apparatus 1 includes an extruder 10, a foaming agent supply source 18, a circular die 20, a mandrel 30, and two winders 40.
The extruder 10 is a so-called tandem type extruder. The extruder 10 includes a first extrusion unit 11 and a second extrusion unit 12 connected to the first extrusion unit 11 by a pipe 16. The first extrusion unit 11 includes a hopper 14. 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. 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.

The raw material which comprises a foam layer is thrown into the 1st extrusion part 11 from the hopper 14. FIG. The raw material thrown in from the hopper 14 is the resin which comprises a foamed layer, the group of inorganic particles, and the arbitrary components mix | blended as needed.
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. Are mixed to obtain a resin composition.
The heating temperature is appropriately determined within the range in which the resin is melted and the optional components are not denatured in consideration of the type of resin and the like.

Examples of the blowing agent include hydrocarbons such as propane, butane, and pentane; halogenated hydrocarbons such as tetrafluoroethane, chlorodifluoroethane, and difluoroethane. Of these, butane is suitable as the foaming agent. Butane may be normal butane or isobutane alone, or a combination of normal butane and isobutane.
These foaming agents may be used alone or in combination of two or more.
The blending amount of the foaming agent is determined in consideration of the type of foaming agent, the overall density required for the foamed sheet, and the like. As for content of a foaming agent, 1.0-7.0 mass parts is preferable with respect to 100 mass parts of thermoplastic resins.

The resin composition is supplied from the first extrusion section 11 to the second extrusion section 12 via the pipe 16 and further mixed. Thereafter, the resin composition is cooled to an arbitrary temperature, and then guided to the resin flow path in the circular die 20.
The resin composition 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.
Thus, a foam sheet having a single layer structure is obtained.

  In addition, as a method of forming a non-foaming layer, the method of obtaining a foaming layer by the above-mentioned manufacturing method and forming a non-foaming layer on this surface by T-die method is mentioned, for example.

(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 lidded container such as a lid; a lid attached to the container body, and the like.
As the use of these containers, for example, for food is preferable.

The thickness of the molded body is determined in consideration of the use and the like, and is preferably 500 to 4000 μm, and more preferably 1000 to 2500 μm, for example.
The overall density of the foamed layer in the molded body is determined in consideration of the use and the like, and is the same as the overall density of the foamed layer 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 it contains a group of inorganic particles, the function of the group of inorganic particles is exhibited. In addition, according to the foamed sheet of the present invention, since the group of inorganic particles including the first group of inorganic particles is contained, the group of inorganic particles is difficult to aggregate. For this reason, the foamed sheet of the present invention increases productivity and hardly causes poor appearance.

(Raw materials used)
PS: Polystyrene resin, MW = 323 × 10 ³ , manufactured by DIC, product name “XC-515”.
PPE: polyphenylene ether resin, manufactured by SABIC, product name: “Noryl EFN4230”.
-Bubble adjusting agent: talc-containing resin composition (containing 40% by mass of talc (average specific surface area of 10 to 40 m ² / g); product name “DSM1401A” manufactured by Toyo Styrene Co., Ltd.).

-Particle group I-1: Baked product of hydrotilesite. Prepared to the standard deviation of the average specific surface area, primary median diameter, primary mode diameter and particle diameter shown in Table 1.
-Particle group I-2: Silica, those prepared to have an average specific surface area, a primary median diameter, a primary mode diameter, and a standard deviation of the particle diameter described in Table 1.
Particle group II-1: Zeolite, prepared with an average specific surface area and a primary median diameter shown in Table 1.
Particle group II-2: Synthetic silica, prepared with an average specific surface area and a primary median diameter shown in Table 1.
Particle group II-3: calcined hydrotalcite The average specific surface area, primary median diameter, primary mode diameter, and standard deviation of particle diameter described in Table 2 were prepared.

(Examples 1-16, 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 Tables 1-5, PS, PPE, a bubble regulator, and the group of inorganic particles were mixed.
The raw material mixture was supplied from the hopper to the first mixing section (screw diameter: 115 mm), heated at the 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 extruded portion, and the resin melt and the foaming agent were mixed to obtain a resin composition. The blending amount of the foaming agent was part by mass shown in Table 1 with respect to 100 parts by mass of the thermoplastic resin.
The resin composition is supplied from the first mixing section to the second mixing section (screw diameter: 180 mm), cooled to 190 ° C., extruded with a circular die (200 mm diameter), and foamed to obtain a cylindrical foam sheet. It was. 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 cooled cylindrical foamed sheet was cut along the extrusion direction to obtain a foamed sheet having a foaming ratio of 8.4 times (density 0.12 g / cm ³ ) and a thickness of 2000 μm.
About the obtained foamed sheet, odor evaluation and aggregation evaluation are performed, and the results are shown in the table.

(Evaluation methods)
<Evaluation of odor>
The residual amounts of normal butyric acid and N-butylformamide, which are off-flavor components derived from the polyphenylene ether resin, were measured by the following method.
Gas chromatograph mass spectrometry (GC / MS measurement) by a purge and trap (P & T) method was performed, and volatile organic compounds generated when the foamed sheet was heated at a temperature of 250 ° C. were measured.
First, the foam sheet was sliced thinly, 3 mg of this was precisely weighed, wrapped in aluminum foil, and set in a glass-lined stainless steel tube (GLT tube).
In this state, the GLT tube was heated at 250 ° C. for 3 minutes, and the generated gas was cold trapped in the cryofocus portion. Then, it thermally desorbed and introduce | transduced the volatile component into GC / MS.
The measurement conditions with GC / MS were as shown below. From the obtained chromatogram, the total ion chromatogram (TIC) peak area of each detected volatile component was determined, and quantified in terms of toluene using the following formula from an absolute calibration curve prepared in advance.

Volatile component concentration (μg / g) = (area value of each component / area value of 1 μg of toluene) × 1 μg / sample weight (g)
In the above formula, the “area value of each component” is the TIC peak area of each detected volatile component.
In the above formula, “the area value of 1 μg of toluene” is “the TIC peak area of the detected toluene (for 1 μg of toluene)” of the calibration curve in “Method for creating calibration curve” below.

≪How to create a calibration curve≫
1 μL of 1000 ppm toluene standard solution was injected into the GLT tube and measured under the following conditions. The detected TIC peak area of toluene (for 1 μg of toluene) was determined, and one inspection quantity curve (straight line) was prepared.

≪GC / MS measurement condition≫
·measuring device:
GC 7890A (manufactured by Agilent Technologies).
Mass spectrometer “JMS-Q1000GC” (manufactured by JEOL Datum).
Column: ZB-1 (1.0 μm × 0.25 mmφ × 60 m: manufactured by Phenomenex).
Column temperature: held at 40 ° C. for 3 minutes, raised to 200 ° C. at 15 ° C./minute, raised to 250 ° C. at 25 ° C./minute, held at 250 ° C. for 6.33 minutes.
Carrier gas: helium (flow rate: 1 mL / min).
Inlet temperature: 250 ° C.
Interface temperature: 250 ° C.
Detector voltage: -960V.
-Split ratio: 1/50.
-Ion source temperature: 250 ° C.
-Ionization current: 300 μA.
-Ionization energy: 70 eV.
Detection method: scanning method (scanning range: m / z 10-400).

≪P & T condition≫
-Apparatus: Thermal desorption apparatus thermal desorption TD-4J (manufactured by Liquid Chloscience).
P & T conditions: ChargeTime (10 s), InjectTime (20 s), DesorbTime (180 s), DelayStartTime (10 s), Desheater (250 ° C.), CryoTemporating (200 ° C.), CryoTemp Cooling (−40 ° C.).

<Odor determination>
After heating the thermoplastic resin foam sheet (10 cm × 10 cm) of each example for 150 seconds in a hot air thermostatic chamber (150 ° C.), one panelist confirmed the odor and evaluated it according to the following evaluation criteria.
≪Evaluation criteria≫
A: Unpleasant odor is hardly felt.
◯: A slight odor is felt.
X: A strange odor is clearly felt.

<Evaluation of productivity>
≪Pressure rise test≫
A 60 mesh screen was placed on both sides of a 200 mesh screen, and these screens were attached to a breaker plate. This breaker plate was attached to the outlet of a single screw extruder (caliber: 40 mm, L / D: 30 mm).
Subsequently, only the resin of each example shown in Table 1 was thrown into the single screw extruder. The resin is melt kneaded in a single screw extruder at a resin temperature of 200 ° C., and extruded from a T die (width: 120 mm, slit clearance: 0.8 mm) attached to the tip of the single screw extruder at an extrusion rate of 5 kg / h. did. The pressure at the tip of the single screw extruder was continuously measured with a pressure gauge, and the pressure when stabilized was taken as the reference pressure P1 (MPa).
According to the composition shown in Table 1, the resin and inorganic particles in each example were charged into a single screw extruder. In the same manner as when the reference pressure P1 was measured, 1 kg of the resin composition of each example was extruded, the pressure at the tip of the single screw extruder was measured, and this was set as the production pressure P2 (MPa).
The rising pressure difference ΔP (MPa) was calculated by the following formula. ΔP was classified into the following criteria, and clogging was evaluated.
ΔP (MPa) = P2 (MPa) −P1 (MPa)

[Evaluation criteria]
(Double-circle): (DELTA) P is less than 1.5 Mpa, it is not clogged at all and productivity is favorable.
◯: ΔP is 1.5 MPa or more and less than 3, and clogging is difficult and productivity is good.
(Triangle | delta): (DELTA) P is 3-7 Mpa, and there is some concern of clogging.
X: ΔP is more than 7 MPa, there is a clear clogging, and the productivity may be lowered.

<Evaluation of sheet appearance>
The foam sheet of each example was visually observed and evaluated according to the following criteria.
A: A groove extending in the MD direction is not recognized on the surface of the foam sheet.
Δ: Slight ridges extending in the MD direction are observed on the surface of the foam sheet.
X: A groove extending in the MD direction is clearly observed on the surface of the foam sheet.

<Comprehensive evaluation>
Comprehensive evaluation was performed according to the following evaluation criteria.
≪Evaluation criteria≫
A: Regarding odor determination, pressure rise test, and sheet appearance evaluation, all are “◯” or “◎”, and “◎” is two or more.
B: Regarding odor determination, pressure increase test, and sheet appearance evaluation, all are “◯” or “◎”, and “◎” is one.
C: All of the odor determination, the pressure increase test, and the evaluation of the sheet appearance are “◯”.
D: Although there is no “x” for odor determination, pressure rise test, and evaluation of sheet appearance, “△” is present.
E: There is one or more “x” for odor determination, pressure increase test, and evaluation of sheet appearance.

As shown in Tables 1 to 5, in Examples 1 to 16 to which the present invention was applied, the residual amounts of normal butyric acid and N-butylformamide were reduced, and the effects of the group of inorganic particles could be exhibited. In addition, in Examples 1 to 16, the results of sensory odor determination were also good.
In addition, in Examples 1 to 16, ΔP was less than 3 MPa, clogging was difficult, and productivity was good. Furthermore, in Examples 1 to 16, the evaluation of the sheet appearance was “◯”.
In Comparative Example 1 which does not contain the first inorganic particle group and contains zeolite as the second inorganic particle group, the evaluation of productivity and sheet appearance is both “x”, and the aggregation of the inorganic particles Could not be suppressed.
In Comparative Example 2 which does not contain the first inorganic particle group and contains synthetic silica as the second inorganic particle group, the productivity and the sheet appearance evaluation are both “Δ”, and the normal butyric acid remains. The amount could not be reduced.
In Comparative Example 3 which did not contain the first inorganic particle group and contained the fired hydrotalcite as the second inorganic particle group, the productivity and the sheet appearance evaluation were both “x”.
In Comparative Example 4 containing both hydrotalcite and zeolite, which are the second group of inorganic particles, the evaluation of productivity was “x” and the evaluation of the sheet appearance was “Δ”.

Claims (11)

Has a foam layer,
The foam layer contains a thermoplastic resin and a group of inorganic particles,
The group of inorganic particles comprises a group of first inorganic particles;
The average specific surface area of the group of the first inorganic particles, 1.0 m ² / g or more 200m less than ² / g, the thermoplastic resin foam sheet.   The thermoplastic resin foam sheet according to claim 1, wherein the content of the first inorganic particles is 10 to 100 parts by mass with respect to 100 parts by mass of the group of inorganic particles. The thermoplastic resin foam sheet according to claim 1 or 2, wherein a bulk density of the group of the first inorganic particles is 0.02 to 1.0 g / cm ³ .   The thermoplastic particles according to any one of claims 1 to 3, wherein the primary particles of the group of the first inorganic particles have a ratio expressed by a mode diameter / median diameter of 0.1 or more and less than 1.0. Resin foam sheet.   The thermoplastic resin foam sheet according to any one of claims 1 to 4, wherein a standard deviation of a median diameter of primary particles of the group of the first inorganic particles is 0.3 µm or more.   The thermoplastic resin foam sheet according to any one of claims 1 to 5, wherein the thermoplastic resin includes a polystyrene-based resin or includes a polystyrene-based resin and a polyphenylene ether-based resin. The thermoplastic resin contains a polyphenylene ether resin,
The thermoplastic resin foam sheet according to any one of claims 1 to 6, wherein the content of the polyphenylene ether resin is 10 to 50 parts by mass with respect to 100 parts by mass of the thermoplastic resin.   The group of the said inorganic particle is at least 1 sort (s) chosen from a bubble regulator, a stabilizer, a ultraviolet absorber, antioxidant, a coloring agent, and a deodorizing agent, It is any one of Claims 1-7. Thermoplastic resin foam sheet.   The thermoplastic resin foam according to any one of claims 1 to 8, wherein a content of the group of the first inorganic particles is 0.05 to 20 parts by mass with respect to 100 parts by mass of the thermoplastic resin. Sheet.   The molded object formed by shape | molding the thermoplastic resin foam sheet as described in any one of Claims 1-9.   The molded article according to claim 10, which is a container for food.

Images