JP2023149906A - Thermoplastic resin foamed molding and method for manufacturing the same - Google Patents

Abstract

To provide a new functionality to a thermoplastic resin foamed body.SOLUTION: A thermoplastic resin foamed molding has a base body 10, and a covering body 20 covering a part or the whole of a surface of the base body 10. The base body 10 is formed by welding two or more first thermoplastic resin foamed particles. The covering body 20 is formed by welding two or more second thermoplastic resin foamed particles. A composition of the first thermoplastic resin foamed particles and a composition of the second thermoplastic resin foamed particles are comprised to be different from each other. The base body 10 and the covering body 20 may be welded at a boundary thereof. The covering body 20 may be freely attachable/detachable to/from the base body 10.SELECTED DRAWING: Figure 1

Description

The present invention relates to a thermoplastic resin foam molded article and a method for producing the same.

Thermoplastic resin foam moldings are sometimes used for fish boxes, cushioning materials, building materials, etc. because they are lightweight, have excellent heat insulation properties, and shock absorption properties.
Thermoplastic resin foam molded products are produced by heating expandable thermoplastic resin particles to form thermoplastic resin foam particles, filling the thermoplastic resin foam particles into the cavity of a mold, and heating them with steam etc. to foam them in the mold. Obtained by molding. In the obtained thermoplastic resin foam molded article, the thermoplastic resin foam particles are fused together.
Conventionally, composite thermoplastic resin foam molded products have been proposed for the purpose of further improving strength and adding new functions.
For example, Patent Document 1 proposes a thermoplastic resin foam molded article in which a non-foamed sheet is provided on the surface of the foamed article.

Japanese Unexamined Patent Publication No. 60-46230

However, the invention described in Patent Document 1 requires the non-foamed sheet to be preformed into a predetermined shape. Therefore, the work process is multi-step and complicated. Furthermore, for example, if a non-foamed sheet of polystyrene resin is molded into the shape of a deep container, defects may occur or the thickness may become uneven. In addition, if the thickness of the non-foamed sheet is increased in order to further improve the strength, the mass of the thermoplastic resin foam molded product will increase, and the advantages of the thermoplastic resin foam molded product will be lost. Additionally, non-foamed sheets cannot accommodate complex shapes.
Therefore, the object of the present invention is to provide a thermoplastic resin molded article that can be provided with new functionality.

The present invention has the following aspects.
<1>
comprising a base and a covering covering part or all of the surface of the base,
The base is formed by fusing two or more first thermoplastic resin foam particles,
The covering body is formed by fusing two or more second thermoplastic resin foam particles,
A thermoplastic resin foam molded article, wherein the composition of the first foamed thermoplastic resin particles is different from the composition of the second foamed thermoplastic resin particles.
<2>
The thermoplastic resin foam molded article according to <1>, wherein the base body and the covering body are fused at a boundary thereof.
<3>
The thermoplastic resin foam molded article according to <1>, wherein the covering body is detachable from the base body.
<4>
The base body has a first fitting part,
The covering has a second fitting portion complementary to the first fitting portion,
The thermoplastic resin foam molded article according to any one of <1> to <3>, wherein the first fitting part and the second fitting part are fitted together.
<5>
The thermoplastic resin foam molded article according to any one of <1> to <4>, wherein the first foamed thermoplastic resin particles have a different color tone from the second foamed thermoplastic resin particles.
<6>
The thermoplastic resin constituting the first expanded thermoplastic resin particles is a recycled raw material,
The thermoplastic resin foam molded article according to any one of <1> to <5>, wherein the thermoplastic resin constituting the second expanded thermoplastic resin particles is a non-recycled raw material.
<7>
It is a container that has a storage chamber inside,
The thermoplastic resin foam molded article according to any one of <1> to <6>, wherein the covering body is located on at least one of the inner surface and the outer surface.

<8>
A method for producing a thermoplastic resin foam molded article according to any one of <1> to <7>,
A base cavity formed between a first male mold and a first female mold is filled with two or more of the first foamed thermoplastic resin particles, and the first thermoplastic resin particles in the base cavity are heated. While heating the foamed plastic resin particles to cause secondary foaming, the first foamed thermoplastic resin particles are fused together to form the base;
Instead of the first male mold, a second male mold smaller than the first male mold is used, and in the male mold side cavity formed between the second male mold and the base body, Filling two or more of the second foamed thermoplastic resin particles, and heating the second foamed thermoplastic resin particles in the male mold side cavity to perform secondary foaming, the second thermoplastic resin A method for manufacturing a thermoplastic resin foam molded article, which comprises heat-sealing expanded particles to each other and molding the covering on the second male mold side.
<9>
After the step of molding the covering on the second male mold side,
Instead of the first female mold, a second female mold larger than the first female mold is used, and in a female mold side cavity formed between the second female mold and the base body, Filling two or more of the second foamed thermoplastic resin particles, and heating the second foamed thermoplastic resin particles in the female mold side cavity to perform secondary foaming, the second thermoplastic resin The method for producing a thermoplastic resin foam molded article according to <8>, wherein the foamed particles are thermally fused to each other to form the covering on the second female mold side.
<10>
A method for producing a thermoplastic resin foam molded article according to any one of <1> to <7>,
A base cavity formed between a first male mold and a first female mold is filled with two or more of the first foamed thermoplastic resin particles, and the first thermoplastic resin particles in the base cavity are heated. Molding the base by fusing the first foamed thermoplastic resin particles to each other while heating the foamed plastic resin particles to perform secondary foaming;
Instead of the first female mold, a second female mold larger than the first female mold is used, and in a female mold side cavity formed between the second female mold and the base body, Filling two or more of the second foamed thermoplastic resin particles, and heating the second foamed thermoplastic resin particles in the female mold side cavity to perform secondary foaming, the second thermoplastic resin A method for producing a thermoplastic resin foam molded article, comprising thermally fusing expanded particles to form the coating on the second female mold side.
<11>
After the step of molding the covering on the second female mold side,
Instead of the first male mold, a second male mold smaller than the first male mold is used, and in the male mold side cavity formed between the second male mold and the base body, Filling two or more of the second foamed thermoplastic resin particles, and heating the second foamed thermoplastic resin particles in the male mold side cavity to perform secondary foaming, the second thermoplastic resin The method for producing a thermoplastic resin foam molded article according to <10>, wherein the expanded particles are thermally fused to each other to form the covering on the second male mold side.
<12>
A base cavity formed between a first male mold and a first female mold is filled with two or more first thermoplastic resin foam particles, and the first thermoplastic resin foam particles in the base cavity are a base forming step of heating the foamed resin particles to perform secondary foaming, and fusing the first foamed thermoplastic resin particles to form a base;
a covering forming step of forming a covering on at least a portion of the surface of the base,
The covering forming step includes at least one of a male side covering forming step and a female side covering forming step,
In the male mold side covering body forming step, a second male mold smaller than the first male mold is used in place of the first male mold, and a second male mold is used between the second male mold and the base body. The formed male mold side cavity is filled with two or more second foamed thermoplastic resin particles having a different composition from the first foamed thermoplastic resin particles, and the second foamed thermoplastic resin particles in the male mold side cavity are filled with While heating the foamed thermoplastic resin particles to cause secondary foaming, the second foamed thermoplastic resin particles are thermally fused to each other to form the coating on the second male mold side;
In the female mold side cover forming step, a second female mold larger than the first female mold is used instead of the first female mold, and a gap is formed between the second female mold and the base body. The formed female mold side cavity is filled with two or more second foamed thermoplastic resin particles having a different composition from the first foamed thermoplastic resin particles, and the second foamed thermoplastic resin particles in the female mold side cavity are filled with The second foamed thermoplastic resin particles are thermally fused to each other while the foamed thermoplastic resin particles are heated to cause secondary foaming, and the covering body is formed on the second female mold side. A method for producing a resin foam molded product.

According to the thermoplastic resin molded article of the present invention, new functionality can be imparted.

FIG. 1 is a perspective view of a container according to an embodiment of the present invention. FIG. 1 is a process diagram showing an example of a method for manufacturing a container according to an embodiment of the present invention. It is a process diagram which shows an example of the manufacturing method of the container based on other embodiment of this invention. It is a process diagram which shows an example of the manufacturing method of the container based on other embodiment of this invention. It is a process diagram which shows an example of the manufacturing method of the container based on other embodiment of this invention.

The thermoplastic resin foam molded article (hereinafter sometimes simply referred to as "foamed molded article") of the present invention has a base body and a covering body.
Further, the method for producing a foamed molded article of the present invention includes a base body molding step and a covering body molding step.
Hereinafter, embodiments of the foamed molded product will be described.

<Thermoplastic resin foam molding>
The foamed molded product 1 in FIG. 1 is a container having a rectangular parallelepiped outer shape and a rectangular parallelepiped storage chamber 2 inside (hereinafter, the foamed molded product 1 may be referred to as a container 1).
That is, the container 1 has a bottom portion 9 that is rectangular in plan view and four side portions 7 rising from the periphery of the bottom portion 9, and the bottom portion 9 and the four side portions 7 surround the storage chamber 2.

The container 1 includes a base 10 and a covering 20 that covers the inner surface of the base 10. The base body 10 forms the outer surface 6 of the container 1 . The covering 20 forms the inner surface 4 of the container 1 . That is, the covering body 20 faces the accommodation chamber 2 .

The size of the container 1 is appropriately determined depending on the application, and for example, a container having external dimensions of 200 to 1500 mm in length x 100 to 1000 mm in width x 50 to 500 mm in height can be exemplified.

≪Base≫
The base body 10 is a foam molded product in which two or more first foamed thermoplastic resin particles are fused together, and is a so-called bead foam molded product.
In this embodiment, the outer shape of the base 10 is equal to the outer shape of the container 1, and the outer dimensions of the base 10 are equal to the outer dimensions of the container 1.
The first foamed thermoplastic resin particles are not particularly limited as long as they are made from a thermoplastic resin and can be shaped into foamed particles, but examples include foamed polystyrene resin particles, foamed polyolefin resin particles, and foamed polyester resin particles. Examples include particles, foamed thermoplastic elastomer resin particles, and the like. Among them, from the viewpoint of increasing the rigidity and versatility of the container 1, polystyrene resin foam particles are preferable as the first thermoplastic resin foam particles.
Note that the first expanded thermoplastic resin particles are a concept that includes particles before foaming (expandable thermoplastic resin particles) in addition to primary foamed particles. When using expandable thermoplastic resin particles as the first expanded thermoplastic resin particles, the expandable thermoplastic resin particles may be filled into a mold and microfoamed during molding.

The expanded polystyrene resin particles contain polystyrene resin. Examples of polystyrene resins 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 and a vinyl monomer that can be polymerized with the styrene monomer: a copolymer of a styrene monomer and a rubber component such as butadiene, a homopolymer of a styrene monomer, or a homopolymer of these monomers. So-called high impact polystyrene, which is a mixture or polymer of a copolymer of a styrene monomer and a 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, Difunctional monomers such as dimethyl maleate, dimethyl fumarate, diethyl fumarate, ethyl fumarate, divinylbenzene, and alkylene glycol dimethacrylate can be mentioned. These vinyl monomers may be used alone or in combination of two or more.
Examples of diene-based rubbery polymers include polybutadiene, styrene-butadiene copolymers, and ethylene-propylene-nonconjugated diene three-dimensional copolymers.
These polystyrene resins may be used alone or in combination of two or more.
As the polystyrene resin, a polystyrene resin containing 50% by mass or more of styrene is preferable, and among them, polystyrene alone is more preferable.

The polystyrene resin may be commercially available polystyrene resin, polystyrene resin newly prepared by a method such as suspension polymerization, polystyrene resin that is not a recycled raw material (non-recycled raw material), or polystyrene resin that is not a recycled raw material. Polystyrene resin may also be used.

When the first foamed thermoplastic resin particles are foamed polystyrene resin particles, the content of the polystyrene resin based on 100 parts by mass of the resin (first thermoplastic resin) constituting the first foamed thermoplastic resin particles is: It is preferably 50 parts by mass or more, more preferably 75 parts by mass or more, even more preferably 90 parts by mass or more, and particularly preferably 95 parts by mass or more. The upper limit of the content of the polystyrene resin is not particularly limited, and may be 100 parts by mass based on 100 parts by mass of the first thermoplastic resin.

The expanded polyolefin resin particles contain a polyolefin resin.
Examples of polyolefin resins include homopolymers of olefin monomers such as ethylene and propylene or copolymers thereof, and copolymers of olefin monomers as a main component and vinyl monomers that can be polymerized with the olefin monomers. etc. These polyolefin resins may be used alone or in combination of two or more.

The polyolefin resin may be a plant-derived resin since it can reduce environmental load. Examples of plant-derived resins include polymers derived from plant materials such as sugarcane and corn. "Derived from plant materials" includes polymers synthesized or extracted from plant materials. Further, for example, "derived from a plant material" includes a polymer obtained by polymerizing a monomer synthesized or extracted from a plant material. "Monomers synthesized or extracted from plant materials" include monomers synthesized using compounds synthesized or extracted from plant materials as raw materials. Plant-derived resins include those in which some of the monomers are "derived from plant materials."
Examples of the plant-derived resin include so-called bio-PE and bio-PP, plant-derived polyethylene resins, plant-derived polypropylene resins, and the like.

When the first foamed thermoplastic resin particles are foamed polyolefin resin particles, the content of the polyolefin resin based on 100 parts by mass of the first thermoplastic resin is preferably 50 parts by mass or more, more preferably 75 parts by mass or more. , more preferably 90 parts by mass or more, particularly preferably 95 parts by mass or more. The upper limit of the content of the polyolefin resin is not particularly limited, and may be 100 parts by mass based on 100 parts by mass of the first thermoplastic resin.

The expanded polyester resin particles contain a polyester resin. Examples of polyester resins include polyethylene terephthalate resin (PET), polybutylene terephthalate resin (PBT), polyethylene naphthalate resin (PEN), polyethylene furanoate resin (PEF), polybutylene naphthalate resin (PBN), and polytrimethylene terephthalate. Examples include resin (PTT), a copolymer of terephthalic acid, ethylene glycol, and cyclohexanedimethanol, and mixtures thereof.
The polyester resin may be a petrochemical-derived polyester resin, a plant-derived polyester resin such as so-called bio-PET, or a mixture thereof.
Examples of the plant-derived polyester resin include biodegradable resins such as polyethylene terephthalate resin, plant-derived polyethylene furanoate resin, plant-derived polytrimethylene terephthalate resin, polylactic acid, and polybutylene succinate.

When the first foamed thermoplastic resin particles are foamed polyester resin particles, the content of the polyester resin based on 100 parts by mass of the first thermoplastic resin is preferably 50 parts by mass or more, more preferably 75 parts by mass or more. , more preferably 90 parts by mass or more, particularly preferably 95 parts by mass or more. The upper limit of the content of the polyester resin is not particularly limited, and may be 100 parts by mass based on 100 parts by mass of the first thermoplastic resin.

The thermoplastic resin may also contain so-called recycled raw materials.
Recycled raw materials include those collected from used foam moldings (e.g., fish boxes, home appliance cushioning materials, food packaging trays, etc.) and regenerated using the limonene dissolution method or heating volume reduction method; Examples include those in which a laminated resin non-foamed sheet is heat-formed into a food packaging tray, and the scraps produced after punching out the food packaging tray are crushed, melted and kneaded to form pellets. In addition to recycled materials obtained by recycling used foam moldings, recycled materials that can be used include home appliances (e.g., televisions, refrigerators, washing machines, air conditioners, etc.), office equipment ( For example, non-foamed foamed molded products separately collected from copying machines, facsimile machines, printers, etc.) are pulverized, melt-kneaded, and re-pelletized.

The content of the recycled raw material relative to the total mass of the first thermoplastic resin is preferably 10% by mass or more, more preferably 30% by mass or more, and even more preferably 50% by mass or more. When the content of recycled raw materials is equal to or higher than the above lower limit, the environmental load can be further reduced. The upper limit of the content of recycled raw materials relative to the total mass of the thermoplastic resin may be 100% by mass, but is preferably 90% by mass or less, and more preferably 85% by mass or less. If the content of the recycled raw material is below the above upper limit, the quality stability of the substrate 10 can be further improved.

The mass average molecular weight Mw of the first thermoplastic resin is determined taking into account the type of the first thermoplastic resin, and is preferably, for example, 100,000 to 450,000, more preferably 120,000 to 400,000. The mass average molecular weight Mw is a value obtained by converting a value measured by gel permeation chromatography (GPC) based on a calibration curve using standard polystyrene.

The melt flow rate (MFR) of the first thermoplastic resin is determined taking into account the type of the first thermoplastic resin, and is preferably 0.3 to 15.0 g/10 min, and 0.5 to 10.0 g/10 min. 10 min is more preferable.
In this specification, the MFR of the thermoplastic resin is based on method B described in JIS K7210:1999 "Plastics - Test method for melt mass flow rate (MFR) and melt volume flow rate (MVR) of thermoplastics", This refers to the value measured under the conditions of a test temperature of 200°C, a test load of 49.03N, and a preheating time of 5 minutes.

Examples of blowing agents include hydrocarbons such as propane, butane, and pentane, halogenated hydrocarbons such as tetrafluoroethane, chlorodifluoroethane, and difluoroethane, carbon dioxide, nitrogen, and water. Among them, butane and pentane are preferable. As the butane, normal butane or isobutane may be used alone, or normal butane and isobutane may be used together in any ratio. As the pentane, normal pentane or isopentane may be used alone, or normal pentane and isopentane may be used in combination in any ratio. These blowing agents may be used alone or in combination of two or more.

The first thermoplastic resin expanded particles may contain other components (first optional component) in addition to the first thermoplastic resin and the blowing agent. Examples of the first optional ingredients include foaming nucleating agents, nucleating agents, ultraviolet absorbers, heat ray shielding materials, antioxidants, coloring agents, antibacterial agents, deodorants, lubricants, flame retardants, antistatic agents, etc. .

Examples of the foaming nucleating agent include talc, sodium hydrogen carbonate, ammonium hydrogen carbonate, calcium carbonate, clay, and citric acid, and among these, talc is more preferred.
The amount of the foaming nucleating agent is not particularly limited, but is preferably 0.01 to 5 parts by weight based on 100 parts by weight of the first thermoplastic resin.

When the first thermoplastic resin contains recycled raw materials, the first thermoplastic resin expanded particles may contain a colorant and a heat ray shielding material.
As the coloring agent, dyes and pigments generally used for polystyrene foams can be used.
Examples of the heat ray shielding material include carbon black and carbon graphite. Examples of carbon black include furnace black, acetylene black, and thermal black.
The content of the colorant and heat ray shielding material in the first thermoplastic resin expanded particles is preferably 0.005 to 10.0 parts by mass, and 0.01 to 10.0 parts by mass, based on 100 parts by mass of the first thermoplastic resin. 0 parts by mass is more preferred, and 0.1 to 8.0 parts by mass is even more preferred.

The thickness w10 of the base body 10 is appropriately determined in consideration of the internal capacity of the container 1, and is, for example, 10 to 50 mm.

The density of the substrate 10 is, for example, preferably 0.01 to 0.10 g/cm ³ , more preferably 0.012 to 0.05 g/cm ³ , and even more preferably 0.012 to 0.03 g/cm ³ . When the density is equal to or higher than the above lower limit, the strength of the base body 10 can be further increased. When the density is less than or equal to the above upper limit, the weight of the base body 10 can be further reduced.

The expansion bulk ratio of the first expanded thermoplastic resin particles in the base body 10 is, for example, 10 to 100 times. The foaming volume ratio is determined by the following formula.
Expanded bulk ratio = Bulk volume of expanded particles (cm ³ ) ÷ Mass of expanded particles (g)

≪Coating body≫
The covering body 20 is formed by fusing two or more second foamed thermoplastic resin particles, and is a so-called bead foam molded body.
The internal shape of the covering 20 may be the same as the internal shape of the container 1 (namely, the shape of the storage chamber 2), or may be a different shape.
Examples of the second expanded thermoplastic resin particles include expanded polystyrene resin particles, expanded polyolefin resin particles, expanded polyester resin particles, and the like. Among these, from the viewpoint of increasing the rigidity of the container 1, polystyrene resin foam particles are preferable as the second thermoplastic resin foam particles.

Note that the second expanded thermoplastic resin particles are a concept that includes particles before foaming (expandable thermoplastic resin particles) in addition to primary foamed particles. When the expandable thermoplastic resin particles are used as the second expanded thermoplastic resin particles, the expandable thermoplastic resin particles may be filled into a mold and microfoamed during molding.

The second thermoplastic resin expanded particles contain a thermoplastic resin (second thermoplastic resin) and a blowing agent.
The second thermoplastic resin is similar to the first thermoplastic resin.
The foaming agent contained in the second foamed thermoplastic resin particles is the same as the foaming agent contained in the first foamed thermoplastic resin particles.
The optional component (second optional component) contained in the second expanded thermoplastic resin particles is the same as the first optional component.

The thickness w20 of the covering body 20 is appropriately determined in consideration of the function of the covering body 20, etc., and is, for example, 1.0 to 20 mm.

The density of the covering body 20 is not particularly limited, and is, for example, in the same range as the density of the base body 10. The density of the covering 20 may be the same as or different from the density of the base 10.

The expansion ratio of the second foamed thermoplastic resin particles is not particularly limited, and is, for example, in the same range as the expansion ratio of the first foamed hot caustic resin particles. The expansion ratio of the second foamed hot caustic resin particles may be the same as or different from the expansion ratio of the first foamed hot caustic resin particles.

The composition of the second foamed thermoplastic resin particles is different from the composition of the first foamed thermoplastic resin particles.
Examples of "different compositions" include the following (a) to (d) and combinations thereof.
(a) The origin of the raw material resin is different. "Origin of raw materials" refers to non-recycled raw materials, recycled raw materials, plant-derived raw materials, etc.
(b) Different types of resin. Different types of resins mean that the types of main monomer units constituting the resins are different, such as one being a polystyrene resin and the other being a polyolefin resin.
(c) The types of optional components are different.
(d) Different foaming ratios. The expansion ratio can be adjusted by a combination of the physical properties (molecular weight, etc.) of the thermoplastic resin and the type or amount of the blowing agent.

An example of (a) is a combination in which the first thermoplastic resin is a recycled raw material and the second thermoplastic resin is a non-recycled raw material. By adopting such a combination, the articles (for example, food, etc.) in the storage chamber 2 do not come into contact with the substrate 10 made of recycled raw materials, thereby increasing the impression of hygiene.

An example of (b) is a combination in which the first thermoplastic resin is a polystyrene resin and the second thermoplastic resin is a polyolefin resin. By employing such a combination, the interface between the base 10 and the covering 20 is not compatible (does not weld), so the covering 20 can be detached from the base 10 and recycling is easy.

An example of (c) is a combination in which a colorant is blended into the first foamed thermoplastic resin particles and no colorant is blended into the second foamed thermoplastic resin particles (a combination of different color tones). By employing such a combination, the design of the container appearance is improved, and unnecessary coloring agents are reduced, resulting in cost savings.
Moreover, as an example of (c), a combination in which the antistatic agent is blended only in the second expanded thermoplastic resin particles can be exemplified. By employing such a combination, it is possible to prevent the effects of static electricity on the articles in the storage chamber 2.
Further, as an example of (c), a combination in which a thermoplastic elastomer having excellent flexibility is blended with the second expanded thermoplastic resin particles can be exemplified. By employing such a combination, it is possible to impart damage resistance to the articles in the storage chamber 2.

As an example of (d), the expansion ratio of the first foamed thermoplastic resin particles is 60 to 90 times, the expansion ratio of the second foamed thermoplastic resin particles is 20 to 60 times, and An example is a combination in which the expansion ratio is lower than the expansion ratio of the expanded resin particles. By adopting such a combination, the rigidity of the storage chamber 2 can be increased, and the strength of the container 1 as a whole can be increased.
Alternatively, the expansion ratio of the first foamed thermoplastic resin particles is 20 to 60 times, the expansion ratio of the second foamed thermoplastic resin particles is 60 to 90 times, and the expansion ratio of the first foamed thermoplastic resin particles is I can give an example of a combination that makes it higher than that. By employing such a combination, the rigidity of the outer surface of the container 1 can be increased, and the strength against external impact can be further increased.

The above (a) to (d) may be combined.
For example, in a combination of (a) and (c), the first thermoplastic resin is a recycled raw material, the second thermoplastic resin is a non-recycled raw material, and a colorant is added to the first thermoplastic resin foam particles. An example of a combination is that the colorant is blended in the coating 20 and the colorant is not blended in the covering body 20. By adopting such a combination, the articles in the storage chamber 2 do not come into contact with the recycled raw materials or the coloring agent.

≪Manufacturing method≫
A method for manufacturing a foamed molded product will be described with reference to FIG. 2, using a method for manufacturing the container 1 as an example.
The method for manufacturing a container according to the present embodiment includes a base molding step and a covering molding step.

In the base body molding step, the first thermoplastic resin foam particles are in-mold foam-molded to form the base body 10 .
As shown in FIG. 2(a), a mold having a first female mold 60a and a first male mold 62a is used, and a base cavity is formed between the first female mold 60a and the first male mold 62a. 61a is formed. The first thermoplastic resin foam particles are filled into the base cavity 61a from the nozzle 52 of the first filling machine 50a.
Next, steam is supplied to the mold to heat the first foamed thermoplastic resin particles in the base cavity 61a to cause secondary foaming, and the first foamed thermoplastic resin particles are fused together to form the base. The base body 10 is molded within the cavity 61a (in-mold foam molding).

Next, in a covering body forming step, the covering body 20 is molded. As shown in FIG. 2(b), the first male die 62a is removed from the first female die 60a, the second male die 62b is assembled with the first female die 60a, and the base 10 and the second male die are assembled. 62b, a male mold side cavity 61b is formed. The second foamed thermoplastic resin particles are filled into the male mold side cavity 61b from the nozzle 52 of the second filling machine 50b. By supplying steam to the mold, the second foamed thermoplastic resin particles in the male mold side cavity 61b are heated to cause secondary foaming, and the second foamed thermoplastic resin particles are fused together to form a male mold. The covering body 20 is molded within the mold side cavity 61b (in-mold foam molding).
If the thermoplastic resin of the first foamed thermoplastic resin particles and the thermoplastic resin of the second foamed thermoplastic resin particles are compatible, the base 10 and the covering 20 are separated at the boundary in the coating forming process. fuse.
In this way, a container 1 in which the base body 10 and the covering body 20 are integrated is obtained.

According to this embodiment, since the base body 10 and the covering body 20 are formed of foamed thermoplastic resin particles having different compositions, a new function can be imparted to the container 1. In addition, since both the base body 10 and the covering body 20 are made of foamed resin, the functions required of a foamed molded product such as light weight, heat insulation properties, and shock absorption properties are maintained.
In addition, according to this embodiment, there is no need to pre-shape the covering 20, so the step of assembling the container 1 can be omitted and manufacturing can be facilitated.
Furthermore, according to this embodiment, since the bead foam molded body is used as the covering body 20, a foam molded body having a complicated shape can be easily molded.

<Other embodiments>
The invention is not limited to the embodiments described above.
The foamed molded article of the present invention may have a fitting portion in each of the base body and the covering body. As shown in FIG. 3(a), a mold having a first female mold 70a having a plurality of protrusions 73 on the inner surface of the bottom and a first male mold 62a is used. The base cavity 71a between the mold and the male mold 62a is filled with the first foamed thermoplastic resin particles. Next, steam is supplied to the mold to heat the first foamed thermoplastic resin particles in the base cavity 71a to cause secondary foaming, and the first foamed thermoplastic resin particles are fused together to form the base. The base 10a is molded within the cavity 71a (base molding step). As shown in FIG. 3(b) (AA cross section in FIG. 3(a)), the obtained base body 10a has a through hole or a concave first fitting portion 13 formed at the bottom thereof.

As shown in FIG. 4(a), the first male mold 62a is removed from the mold, the second male mold 62b is combined with the first female mold 70a, and the gap between the base body 10a and the second male mold 62b is A male mold side cavity 71b is formed in. The second male die 62b has a larger outer shape than the first male die 62a. The male mold side cavity 71b is filled with second foamed thermoplastic resin particles. At this time, the first fitting portion 13 is also filled with the second foamed thermoplastic resin particles. By supplying steam to the mold, the second foamed thermoplastic resin particles in the male mold side cavity 71b are heated to cause secondary foaming, and the second foamed thermoplastic resin particles are fused together to form a male mold. The covering body 20a is molded on the second male mold side within the mold side cavity 71b to obtain a container 1a in which the base body 10a and the covering body 20a are integrated (covering body molding step). At this time, a convex second fitting part 23 is formed in the first fitting part 13 by in-mold foam molding of the second foamed thermoplastic resin particles (FIG. 4(b)). (See BB cross section in 4(a)). Therefore, the second fitting part 23 is complementary to the first fitting part 13, and the first fitting part 13 and the second fitting part 23 are fitted together.

By fitting the first fitting part 13 and the second fitting part 23 together, separation of the base body 10 and the covering body 20a can be more reliably prevented. In addition, since the second fitting part 23 bites into the bottom, the strength of the bottom can be further increased by using foamed thermoplastic resin particles with a low expansion ratio as the second foamed thermoplastic resin particles.
In addition, in this example, the first fitting part is made concave and the second fitting part is made convex, but the present invention is not limited to this. The first fitting part and the second fitting part may have complementary shapes, and the first fitting part may be a groove, a through hole, or a convex shape such as a protrusion or a protrusion.

The method for producing a foamed molded article of the present invention may use, for example, the apparatus shown in FIG. The mold 80 in FIG. 5 has two female molds 80a. The mold 80 is rotatable about the axis O1. In the mold 80, the female molds 80a and 80a are provided with their bottom surfaces facing each other. That is, the two female molds 80a are open in opposite directions. Note that the inner shapes of the two female molds 80a are the same.
First, the first male die 82a is combined with the female die 80a, and a base cavity 81a is formed between the female die 80a and the first male die 82a. First foamed thermoplastic resin particles are filled into the base cavity 81a from the nozzle 52 of the first filling machine 50a.
Next, steam is supplied to the mold 80 to heat the first foamed thermoplastic resin particles in the base cavity 81a to cause secondary foaming, while fusing the first foamed thermoplastic resin particles to each other, The base 10 is molded within the base cavity 81a (base molding step).

Next, the first male mold 82a is removed from the female mold 80a, the mold 80 is inverted about the axis O1, the second male mold 82b is combined with the female mold 80a having the base 10, and the base 10 and the second A male mold side cavity 81b is formed between the male mold 82b and the male mold 82b. The second foamed thermoplastic resin particles are filled into the male mold side cavity 81b from the nozzle 52 of the second filling machine 50b. Supplying steam to the mold 80 and heating the second foamed thermoplastic resin particles in the male mold side cavity 81b to cause secondary foaming, while fusing the second foamed thermoplastic resin particles to each other, The covering body 20 is molded on the second male mold side within the male mold side cavity 81b to obtain a container 1 in which the base body 10 and the covering body 20 are integrated (covering body molding step).
During molding of the covering body 20, the first male mold 82a is combined with the female mold 80a facing the first filling machine 50a, and the base body 10 is molded.
According to the manufacturing method of this example, by inverting the mold in which two female molds are combined, the base body and the covering body can be continuously molded, and productivity can be further improved.

In the embodiments described above, the covering is provided on the entire inner surface of the container, but the present invention is not limited thereto, and the covering may be provided on the outer surface of the container, or on the inner and outer surfaces of the container. It may be provided on both sides. Alternatively, the covering may be provided only on a portion of the inner or outer surface of the container.
When providing a covering on the outer surface of a container, the following manufacturing method can be exemplified.
A base cavity formed between a first male mold and a first female mold is filled with first foamed thermoplastic resin particles. While heating the first foamed thermoplastic resin particles in the base cavity to cause secondary foaming, the first foamed thermoplastic resin particles are fused together to form a base (base molding step).
Next, in place of the first female mold, a second female mold having an inner surface shape larger than that of the first female mold is used, and a mold is placed in the female mold side cavity formed between the second female mold and the base body. , filling the second thermoplastic foam particles. While heating the second foamed thermoplastic resin particles in the female mold side cavity to cause secondary foaming, the second foamed thermoplastic resin particles are thermally fused to each other to form a covering on the second female mold side. (covering body forming process). In this way, a container whose outer surface is provided with a covering is obtained.

In the present invention, the above-described molding method may be repeated multiple times to form two or more coverings. Two or more coatings may be provided on both sides of the substrate, or two or more layers may be laminated on one surface of the substrate. When two or more covering bodies are provided, the second thermoplastic resin foam particles in each covering body may have the same composition or may have different compositions.

For example, the method may include a step of forming a covering on the male mold side and then forming a covering on the female mold side. An example of this method is to form a covering on the male mold side, then replace the first female mold with a second female mold that has a larger inner surface shape than the first female mold, and then A female mold side cavity formed between the mold and the base body is filled with second foamed thermoplastic resin particles. While heating the second foamed thermoplastic resin particles in the female mold side cavity to cause secondary foaming, the second foamed thermoplastic resin particles are thermally fused to each other to form a covering on the second female mold side. (female mold side covering body forming process). In this way, a container is obtained in which the covering is provided on both the male side (inner surface) and the female side (outer surface).

Alternatively, for example, the method may include a step of forming a covering on the male mold side after forming the covering on the female mold side. As an example of this method, after forming a covering on the female mold side, a second male mold with a smaller external shape than the first male mold is used in place of the first male mold, and a second male mold is used. The male mold side cavity formed between the mold and the base body is filled with second foamed thermoplastic resin particles. While heating the second foamed thermoplastic resin particles in the male mold side cavity to cause secondary foaming, the second foamed thermoplastic resin particles are thermally fused to each other to form a covering on the male mold side ( (male side cover forming process). In this way, a container is obtained in which the covering is provided on both the male side (inner surface) and the female side (outer surface).

In the embodiments described above, the surface of the foamed molded product is formed of a foamed molded product, but the present invention is not limited thereto, and a non-foamed sheet may be provided on part or all of the surface.

In the embodiments described above, the foam molded article is a container, but the present invention is not limited thereto. The foam molded article of the present invention may be a flat display board, an interior material for an automobile, a cushioning material for an electronic device, or the like.
Moreover, the covering body may be provided in any region of the base body depending on the use, function, and shape of the foamed molded body.

The present invention will be explained in more detail below with reference to Examples, but the present invention is not limited to the Examples.

(Example 1)
After preliminary washing, polystyrene foam fish boxes recovered from the market were melted again using an extruder, extruded into strands through small holes, cooled with water, and cut into cylindrical shapes with a diameter of 1 mm and a length of 1 mm. The obtained cylindrical recycled polystyrene particles were impregnated with a blowing agent, pentane, in an aqueous suspension to obtain expandable recycled polystyrene particles.
This expandable recycled polystyrene was pre-foamed to a bulk factor of 50 to obtain first foamed thermoplastic resin particles.

The styrene monomer was dispersed in an aqueous suspension, and the polymerization was accelerated with peroxide to complete the polymerization. This was impregnated with pentane as a blowing agent to obtain particulate expandable virgin polystyrene resin particles. That is, the thermoplastic resin of the expandable virgin polystyrene resin particles is a non-recycled raw material. These expandable virgin polystyrene particles were pre-foamed to a bulk factor of 50 to obtain second foamed thermoplastic resin particles.

Using the apparatus shown in FIG. 2, a base was molded from the first foamed thermoplastic resin particles, and a covering was molded onto the inner surface of the base from the second foamed thermoplastic resin particles to obtain a container.
In the obtained container, a foamed molded article using a thermoplastic resin as a non-recycled raw material was located on the inner surface of the container, and the rest of the container was a foamed molded article using a thermoplastic resin as a recycled raw material.
For this reason, the inner surface of the container can be brought into direct contact with food, making it suitable for food transportation, and the container as a whole is mainly made of recycled raw materials, reducing environmental impact.

1, 1a Thermoplastic resin foam molded body 2 Storage chamber 4 Inner surface 6 Outer surface 10, 10a Base body 13 First fitting part 20, 20a Covering body 23 Second fitting part 60a, 70a, 80a Female mold 61a, 71a, 81a Base cavity 61b, 71b, 81b Male mold side cavity 62a, 72a, 82a, 82b Male mold 80 Mold

Claims (12)

comprising a base and a covering covering part or all of the surface of the base,
The base is formed by fusing two or more first thermoplastic resin foam particles,
The covering body is formed by fusing two or more second thermoplastic resin foam particles,
A thermoplastic resin foam molded article, wherein the composition of the first foamed thermoplastic resin particles is different from the composition of the second foamed thermoplastic resin particles. The thermoplastic resin foam molded article according to claim 1, wherein the base body and the covering body are fused at a boundary thereof. The thermoplastic resin foam molded article according to claim 1, wherein the covering body is detachable from the base body. The base body has a first fitting part,
The covering has a second fitting portion complementary to the first fitting portion,
The thermoplastic resin foam molded article according to any one of claims 1 to 3, wherein the first fitting part and the second fitting part are fitted together. The thermoplastic resin foam molded article according to any one of claims 1 to 4, wherein the first foamed thermoplastic resin particles have a different color tone from the second foamed thermoplastic resin particles. The thermoplastic resin constituting the first expanded thermoplastic resin particles is a recycled raw material,
The thermoplastic resin foam molded article according to any one of claims 1 to 5, wherein the thermoplastic resin constituting the second foamed thermoplastic resin particles is a non-recycled raw material. It is a container that has a storage chamber inside,
The thermoplastic resin foam molded article according to any one of claims 1 to 6, wherein the covering is located on at least one of an inner surface and an outer surface. A method for producing a thermoplastic resin foam molded article according to any one of claims 1 to 7, comprising:
A base cavity formed between a first male mold and a first female mold is filled with two or more of the first foamed thermoplastic resin particles, and the first thermoplastic resin particles in the base cavity are heated. While heating the foamed plastic resin particles to cause secondary foaming, the first foamed thermoplastic resin particles are fused together to form the base;
Instead of the first male mold, a second male mold smaller than the first male mold is used, and in the male mold side cavity formed between the second male mold and the base body, Filling two or more of the second foamed thermoplastic resin particles, and heating the second foamed thermoplastic resin particles in the male mold side cavity to perform secondary foaming, the second thermoplastic resin A method for manufacturing a thermoplastic resin foam molded article, which comprises heat-sealing expanded particles to each other and molding the covering on the second male mold side. After the step of molding the covering on the second male mold side,
Instead of the first female mold, a second female mold larger than the first female mold is used, and in a female mold side cavity formed between the second female mold and the base body, Filling two or more of the second foamed thermoplastic resin particles, and heating the second foamed thermoplastic resin particles in the female mold side cavity to perform secondary foaming, the second thermoplastic resin 9. The method for manufacturing a thermoplastic resin foam molded article according to claim 8, wherein the covering body is formed on the second female mold side by heat-sealing the expanded particles. A method for producing a thermoplastic resin foam molded article according to any one of claims 1 to 7, comprising:
A base cavity formed between a first male mold and a first female mold is filled with two or more of the first foamed thermoplastic resin particles, and the first thermoplastic resin particles in the base cavity are heated. Molding the base by fusing the first foamed thermoplastic resin particles to each other while heating the foamed plastic resin particles to perform secondary foaming;
Instead of the first female mold, a second female mold larger than the first female mold is used, and in a female mold side cavity formed between the second female mold and the base body, Filling two or more of the second foamed thermoplastic resin particles, and heating the second foamed thermoplastic resin particles in the female mold side cavity to perform secondary foaming, the second thermoplastic resin A method for producing a thermoplastic resin foam molded article, comprising thermally fusing expanded particles to form the coating on the second female mold side. After the step of molding the covering on the second female mold side,
Instead of the first male mold, a second male mold smaller than the first male mold is used, and in the male mold side cavity formed between the second male mold and the base body, Filling two or more of the second foamed thermoplastic resin particles, and heating the second foamed thermoplastic resin particles in the male mold side cavity to perform secondary foaming, the second thermoplastic resin 11. The method for producing a thermoplastic resin foam molded article according to claim 10, wherein the covering body is formed on the second male mold side by heat-sealing the expanded particles. A base cavity formed between a first male mold and a first female mold is filled with two or more first thermoplastic resin foam particles, and the first thermoplastic resin foam particles in the base cavity are a base forming step of heating the foamed resin particles to perform secondary foaming, and fusing the first foamed thermoplastic resin particles to form a base;
a covering forming step of forming a covering on at least a portion of the surface of the base,
The covering forming step includes at least one of a male side covering forming step and a female side covering forming step,
In the male mold side covering body forming step, a second male mold smaller than the first male mold is used in place of the first male mold, and a second male mold is used between the second male mold and the base body. The formed male mold side cavity is filled with two or more second foamed thermoplastic resin particles having a different composition from the first foamed thermoplastic resin particles, and the second foamed thermoplastic resin particles in the male mold side cavity are filled with While heating the foamed thermoplastic resin particles to cause secondary foaming, the second foamed thermoplastic resin particles are thermally fused to each other to form the coating on the second male mold side;
In the female mold side cover forming step, a second female mold larger than the first female mold is used instead of the first female mold, and a gap is formed between the second female mold and the base body. The formed female mold side cavity is filled with two or more second foamed thermoplastic resin particles having a different composition from the first foamed thermoplastic resin particles, and the second foamed thermoplastic resin particles in the female mold side cavity are The second foamed thermoplastic resin particles are heat-sealed to each other while the foamed thermoplastic resin particles are heated to cause secondary foaming, and the covering body is formed on the second female mold side. A method for producing a resin foam molded product.

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